Snap for 6877830 from 27aff84c5e4cf60a40982c3f7e9cc7606e3c9804 to sdk-release

Change-Id: If7b52b7f5d70ec1675400821beaa019a2f14cadb
diff --git a/.cargo_vcs_info.json b/.cargo_vcs_info.json
index fe3ac73..f8f6640 100644
--- a/.cargo_vcs_info.json
+++ b/.cargo_vcs_info.json
@@ -1,5 +1,5 @@
 {
   "git": {
-    "sha1": "70b78abf071a2849e20861df99bbd6b1e889ef71"
+    "sha1": "aa4c0375cd94ed4d1b5de7ce0bb3369262dae7e2"
   }
 }
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 0000000..ed53c52
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,83 @@
+name: CI

+on: [push, pull_request]

+

+jobs:

+  test:

+    name: Test

+    runs-on: ${{ matrix.os }}

+    strategy:

+      matrix:

+        build: [stable, beta, nightly, macos, win32, win64, mingw]

+        include:

+          - build: stable

+            os: ubuntu-latest

+            rust: stable

+          - build: beta

+            os: ubuntu-latest

+            rust: beta

+          - build: nightly

+            os: ubuntu-latest

+            rust: nightly

+          - build: macos

+            os: macos-latest

+            rust: stable

+          - build: win32

+            os: windows-latest

+            rust: stable-i686

+          - build: win64

+            os: windows-latest

+            rust: stable-x86_64

+          - build: mingw

+            os: windows-latest

+            rust: stable-x86_64-gnu

+    steps:

+    - uses: actions/checkout@master

+    - name: Install Rust (rustup)

+      run: |

+        rustup update ${{ matrix.rust }} --no-self-update

+        rustup default ${{ matrix.rust }}

+    - run: cargo test --verbose

+    - run: cargo test --verbose --features serde

+    - run: cargo test --verbose --features std

+    - run: cargo test --verbose --features kv_unstable

+    - run: cargo test --verbose --features "kv_unstable std"

+    - run: cargo test --verbose --features "kv_unstable_sval"

+    - run: cargo run --verbose --manifest-path test_max_level_features/Cargo.toml

+    - run: cargo run --verbose --manifest-path test_max_level_features/Cargo.toml --release

+

+  rustfmt:

+    name: Rustfmt

+    runs-on: ubuntu-latest

+    steps:

+    - uses: actions/checkout@master

+    - name: Install Rust

+      run: |

+        rustup update stable --no-self-update

+        rustup default stable

+        rustup component add rustfmt

+    - run: cargo fmt -- --check

+

+  msrv:

+    name: MSRV

+    runs-on: ubuntu-latest

+    steps:

+      - uses: actions/checkout@master

+      - name: Install Rust

+        run: |

+          rustup update 1.31.0 --no-self-update

+          rustup default 1.31.0

+      - run: cargo build --verbose

+      - run: cargo build --verbose --features serde

+      - run: cargo build --verbose --features std

+

+  embedded:

+    name: Embedded

+    runs-on: ubuntu-latest

+    steps:

+      - uses: actions/checkout@master

+      - name: Install Rust

+        run: |

+          rustup update stable --no-self-update

+          rustup default stable

+      - run: rustup target add thumbv6m-none-eabi

+      - run: cargo build --verbose --target=thumbv6m-none-eabi

diff --git a/.gitignore b/.gitignore
index 2c96eb1..41488a8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,2 @@
-target/
-Cargo.lock
+target/

+Cargo.lock

diff --git a/Android.bp b/Android.bp
index 8b34d8b..71d17d4 100644
--- a/Android.bp
+++ b/Android.bp
@@ -3,7 +3,6 @@
 rust_library {
     name: "liblog_rust",
     stem: "liblog",
-    // has rustc warnings
     host_supported: true,
     crate_name: "log",
     srcs: ["src/lib.rs"],
diff --git a/CHANGELOG.md b/CHANGELOG.md
index e04562b..296b49b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,145 +1,186 @@
-# Change Log
-
-## [Unreleased]
-
-## [0.4.8] - 2019-07-28
-
-### New
-
-* Support attempting to get `Record` fields as static strings.
-
-## [0.4.7] - 2019-07-06
-
-### New
-
-* Support for embedded environments with thread-unsafe initialization.
-* Initial unstable support for capturing structured data under the `kv_unstable`
-feature gate. This new API doesn't affect existing users and may change in future
-patches (so those changes may not appear in the changelog until it stabilizes).
-
-### Improved
-
-* Docs for using `log` with the 2018 edition.
-* Error messages for macros missing arguments.
-
-## [0.4.6] - 2018-10-27
-
-### Improved
-
-* Support 2018-style macro import for the `log_enabled!` macro.
-
-## [0.4.5] - 2018-09-03
-
-### Improved
-
-* Make `log`'s internal helper macros less likely to conflict with user-defined
-  macros.
-
-## [0.4.4] - 2018-08-17
-
-### Improved
-
-* Support 2018-style imports of the log macros.
-
-## [0.4.3] - 2018-06-29
-
-### Improved
-
-* More code generation improvements.
-
-## [0.4.2] - 2018-06-05
-
-### Improved
-
-* Log invocations now generate less code.
-
-### Fixed
-
-* Example Logger implementations now properly set the max log level.
-
-## [0.4.1] - 2017-12-30
-
-### Fixed
-
-* Some doc links were fixed.
-
-## [0.4.0] - 2017-12-24
-
-The changes in this release include cleanup of some obscure functionality and a more robust public
-API designed to support bridges to other logging systems, and provide more flexibility to new
-features in the future.
-
-### Compatibility
-
-Vast portions of the Rust ecosystem use the 0.3.x release series of log, and we don't want to force
-the community to go through the pain of upgrading every crate to 0.4.x at the exact same time. Along
-with 0.4.0, we've published a new 0.3.9 release which acts as a "shim" over 0.4.0. This will allow
-crates using either version to coexist without losing messages from one side or the other.
-
-There is one caveat - a log message generated by a crate using 0.4.x but consumed by a logging
-implementation using 0.3.x will not have a file name or module path. Applications affected by this
-can upgrade their logging implementations to one using 0.4.x to avoid losing this information. The
-other direction does not lose any information, fortunately!
-
-**TL;DR** Libraries should feel comfortable upgrading to 0.4.0 without treating that as a breaking
-change. Applications may need to update their logging implementation (e.g. env-logger) to a newer
-version using log 0.4.x to avoid losing module and file information.
-
-### New
-
-* The crate is now `no_std` by default.
-* `Level` and `LevelFilter` now implement `Serialize` and `Deserialize` when the `serde` feature is
-    enabled.
-* The `Record` and `Metadata` types can now be constructed by third-party code via a builder API.
-* The `logger` free function returns a reference to the logger implementation. This, along with the
-    ability to construct `Record`s, makes it possible to bridge from another logging framework to
-    this one without digging into the private internals of the crate. The standard `error!` `warn!`,
-    etc, macros now exclusively use the public API of the crate rather than "secret" internal APIs.
-* `Log::flush` has been added to allow crates to tell the logging implementation to ensure that all
-    "in flight" log events have been persisted. This can be used, for example, just before an
-    application exits to ensure that asynchronous log sinks finish their work.
-
-### Removed
-
-* The `shutdown` and `shutdown_raw` functions have been removed. Supporting shutdown significantly
-    complicated the implementation and imposed a performance cost on each logging operation.
-* The `log_panics` function and its associated `nightly` Cargo feature have been removed. Use the
-    [log-panics](https://crates.io/crates/log-panics) instead.
-
-### Changed
-
-* The `Log` prefix has been removed from type names. For example, `LogLevelFilter` is now
-    `LevelFilter`, and `LogRecord` is now `Record`.
-* The `MaxLogLevelFilter` object has been removed in favor of a `set_max_level` free function.
-* The `set_logger` free functions have been restructured. The logger is now directly passed to the
-    functions rather than a closure which returns the logger. `set_logger` now takes a `&'static
-    Log` and is usable in `no_std` contexts in place of the old `set_logger_raw`. `set_boxed_logger`
-    is a convenience function which takes a `Box<Log>` but otherwise acts like `set_logger`. It
-    requires the `std` feature.
-* The `file` and `module_path` values in `Record` no longer have the `'static` lifetime to support
-    integration with other logging frameworks that don't provide a `'static` lifetime for the
-    equivalent values.
-* The `file`, `line`, and `module_path` values in `Record` are now `Option`s to support integration
-    with other logging frameworks that don't provide those values.
-
-### In the Future
-
-* We're looking to add support for *structured* logging - the inclusion of extra key-value pairs of
-    information in a log event in addition to the normal string message. This should be able to be
-    added in a backwards compatible manner to the 0.4.x series when the design is worked out.
-
-## Older
-
-Look at the [release tags] for information about older releases.
-
-[Unreleased]: https://github.com/rust-lang-nursery/log/compare/0.4.8...HEAD
-[0.4.8]: https://github.com/rust-lang-nursery/log/compare/0.4.7...0.4.8
-[0.4.7]: https://github.com/rust-lang-nursery/log/compare/0.4.6...0.4.7
-[0.4.6]: https://github.com/rust-lang-nursery/log/compare/0.4.5...0.4.6
-[0.4.5]: https://github.com/rust-lang-nursery/log/compare/0.4.4...0.4.5
-[0.4.4]: https://github.com/rust-lang-nursery/log/compare/0.4.3...0.4.4
-[0.4.3]: https://github.com/rust-lang-nursery/log/compare/0.4.2...0.4.3
-[0.4.2]: https://github.com/rust-lang-nursery/log/compare/0.4.1...0.4.2
-[0.4.1]: https://github.com/rust-lang-nursery/log/compare/0.4.0...0.4.1
-[0.4.0]: https://github.com/rust-lang-nursery/log/compare/0.3.8...0.4.0
-[release tags]: https://github.com/rust-lang-nursery/log/releases
+# Change Log

+

+## [Unreleased]

+

+## [0.4.11] - 2020-07-09

+

+### New

+

+* Support coercing structured values into concrete types.

+* Reference the `win_dbg_logger` in the readme.

+

+### Fixed

+

+* Updates a few deprecated items used internally.

+* Fixed issues in docs and expands sections.

+* Show the correct build badge in the readme.

+* Fix up a possible inference breakage with structured value errors.

+* Respect formatting flags in structured value formatting.

+

+## [0.4.10] - 2019-12-16 (yanked)

+

+### Fixed

+

+* Fixed the `log!` macros so they work in expression context (this regressed in `0.4.9`, which has been yanked).

+

+## [0.4.9] - 2019-12-12 (yanked)

+

+### Minimum Supported Rust Version

+

+This release bumps the minimum compiler version to `1.31.0`. This was mainly needed for `cfg-if`,

+but between `1.16.0` and `1.31.0` there are a lot of language and library improvements we now

+take advantage of.

+

+### New

+

+* Unstable support for capturing key-value pairs in a record using the `log!` macros

+

+### Improved

+

+* Better documentation for max level filters.

+* Internal updates to line up with bumped MSRV

+

+## [0.4.8] - 2019-07-28

+

+### New

+

+* Support attempting to get `Record` fields as static strings.

+

+## [0.4.7] - 2019-07-06

+

+### New

+

+* Support for embedded environments with thread-unsafe initialization.

+* Initial unstable support for capturing structured data under the `kv_unstable`

+feature gate. This new API doesn't affect existing users and may change in future

+patches (so those changes may not appear in the changelog until it stabilizes).

+

+### Improved

+

+* Docs for using `log` with the 2018 edition.

+* Error messages for macros missing arguments.

+

+## [0.4.6] - 2018-10-27

+

+### Improved

+

+* Support 2018-style macro import for the `log_enabled!` macro.

+

+## [0.4.5] - 2018-09-03

+

+### Improved

+

+* Make `log`'s internal helper macros less likely to conflict with user-defined

+  macros.

+

+## [0.4.4] - 2018-08-17

+

+### Improved

+

+* Support 2018-style imports of the log macros.

+

+## [0.4.3] - 2018-06-29

+

+### Improved

+

+* More code generation improvements.

+

+## [0.4.2] - 2018-06-05

+

+### Improved

+

+* Log invocations now generate less code.

+

+### Fixed

+

+* Example Logger implementations now properly set the max log level.

+

+## [0.4.1] - 2017-12-30

+

+### Fixed

+

+* Some doc links were fixed.

+

+## [0.4.0] - 2017-12-24

+

+The changes in this release include cleanup of some obscure functionality and a more robust public

+API designed to support bridges to other logging systems, and provide more flexibility to new

+features in the future.

+

+### Compatibility

+

+Vast portions of the Rust ecosystem use the 0.3.x release series of log, and we don't want to force

+the community to go through the pain of upgrading every crate to 0.4.x at the exact same time. Along

+with 0.4.0, we've published a new 0.3.9 release which acts as a "shim" over 0.4.0. This will allow

+crates using either version to coexist without losing messages from one side or the other.

+

+There is one caveat - a log message generated by a crate using 0.4.x but consumed by a logging

+implementation using 0.3.x will not have a file name or module path. Applications affected by this

+can upgrade their logging implementations to one using 0.4.x to avoid losing this information. The

+other direction does not lose any information, fortunately!

+

+**TL;DR** Libraries should feel comfortable upgrading to 0.4.0 without treating that as a breaking

+change. Applications may need to update their logging implementation (e.g. env-logger) to a newer

+version using log 0.4.x to avoid losing module and file information.

+

+### New

+

+* The crate is now `no_std` by default.

+* `Level` and `LevelFilter` now implement `Serialize` and `Deserialize` when the `serde` feature is

+    enabled.

+* The `Record` and `Metadata` types can now be constructed by third-party code via a builder API.

+* The `logger` free function returns a reference to the logger implementation. This, along with the

+    ability to construct `Record`s, makes it possible to bridge from another logging framework to

+    this one without digging into the private internals of the crate. The standard `error!` `warn!`,

+    etc, macros now exclusively use the public API of the crate rather than "secret" internal APIs.

+* `Log::flush` has been added to allow crates to tell the logging implementation to ensure that all

+    "in flight" log events have been persisted. This can be used, for example, just before an

+    application exits to ensure that asynchronous log sinks finish their work.

+

+### Removed

+

+* The `shutdown` and `shutdown_raw` functions have been removed. Supporting shutdown significantly

+    complicated the implementation and imposed a performance cost on each logging operation.

+* The `log_panics` function and its associated `nightly` Cargo feature have been removed. Use the

+    [log-panics](https://crates.io/crates/log-panics) instead.

+

+### Changed

+

+* The `Log` prefix has been removed from type names. For example, `LogLevelFilter` is now

+    `LevelFilter`, and `LogRecord` is now `Record`.

+* The `MaxLogLevelFilter` object has been removed in favor of a `set_max_level` free function.

+* The `set_logger` free functions have been restructured. The logger is now directly passed to the

+    functions rather than a closure which returns the logger. `set_logger` now takes a `&'static

+    Log` and is usable in `no_std` contexts in place of the old `set_logger_raw`. `set_boxed_logger`

+    is a convenience function which takes a `Box<Log>` but otherwise acts like `set_logger`. It

+    requires the `std` feature.

+* The `file` and `module_path` values in `Record` no longer have the `'static` lifetime to support

+    integration with other logging frameworks that don't provide a `'static` lifetime for the

+    equivalent values.

+* The `file`, `line`, and `module_path` values in `Record` are now `Option`s to support integration

+    with other logging frameworks that don't provide those values.

+

+### In the Future

+

+* We're looking to add support for *structured* logging - the inclusion of extra key-value pairs of

+    information in a log event in addition to the normal string message. This should be able to be

+    added in a backwards compatible manner to the 0.4.x series when the design is worked out.

+

+## Older

+

+Look at the [release tags] for information about older releases.

+

+[Unreleased]: https://github.com/rust-lang-nursery/log/compare/0.4.11...HEAD

+[0.4.11]: https://github.com/rust-lang-nursery/log/compare/0.4.10...0.4.11

+[0.4.10]: https://github.com/rust-lang-nursery/log/compare/0.4.9...0.4.10

+[0.4.9]: https://github.com/rust-lang-nursery/log/compare/0.4.8...0.4.9

+[0.4.8]: https://github.com/rust-lang-nursery/log/compare/0.4.7...0.4.8

+[0.4.7]: https://github.com/rust-lang-nursery/log/compare/0.4.6...0.4.7

+[0.4.6]: https://github.com/rust-lang-nursery/log/compare/0.4.5...0.4.6

+[0.4.5]: https://github.com/rust-lang-nursery/log/compare/0.4.4...0.4.5

+[0.4.4]: https://github.com/rust-lang-nursery/log/compare/0.4.3...0.4.4

+[0.4.3]: https://github.com/rust-lang-nursery/log/compare/0.4.2...0.4.3

+[0.4.2]: https://github.com/rust-lang-nursery/log/compare/0.4.1...0.4.2

+[0.4.1]: https://github.com/rust-lang-nursery/log/compare/0.4.0...0.4.1

+[0.4.0]: https://github.com/rust-lang-nursery/log/compare/0.3.8...0.4.0

+[release tags]: https://github.com/rust-lang-nursery/log/releases

diff --git a/Cargo.toml b/Cargo.toml
index 146060f..bd654d2 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -3,7 +3,7 @@
 # When uploading crates to the registry Cargo will automatically
 # "normalize" Cargo.toml files for maximal compatibility
 # with all versions of Cargo and also rewrite `path` dependencies
-# to registry (e.g. crates.io) dependencies
+# to registry (e.g., crates.io) dependencies
 #
 # If you believe there's an error in this file please file an
 # issue against the rust-lang/cargo repository. If you're
@@ -12,7 +12,7 @@
 
 [package]
 name = "log"
-version = "0.4.8"
+version = "0.4.11"
 authors = ["The Rust Project Developers"]
 build = "build.rs"
 exclude = ["rfcs/**/*", "/.travis.yml", "/appveyor.yml"]
@@ -29,6 +29,10 @@
 [[test]]
 name = "filters"
 harness = false
+
+[[test]]
+name = "macros"
+harness = true
 [dependencies.cfg-if]
 version = "0.1.2"
 
@@ -38,14 +42,14 @@
 default-features = false
 
 [dependencies.sval]
-version = "0.4.2"
+version = "0.5.2"
 optional = true
 default-features = false
 [dev-dependencies.serde_test]
 version = "1.0"
 
 [dev-dependencies.sval]
-version = "0.4.2"
+version = "0.5.2"
 features = ["test"]
 
 [features]
@@ -64,8 +68,3 @@
 release_max_level_trace = []
 release_max_level_warn = []
 std = []
-[badges.appveyor]
-repository = "alexcrichton/log"
-
-[badges.travis-ci]
-repository = "rust-lang-nursery/log"
diff --git a/Cargo.toml.orig b/Cargo.toml.orig
index e7e7892..447469e 100644
--- a/Cargo.toml.orig
+++ b/Cargo.toml.orig
@@ -1,58 +1,58 @@
-[package]
-
-name = "log"
-version = "0.4.8" # remember to update html_root_url
-authors = ["The Rust Project Developers"]
-license = "MIT OR Apache-2.0"
-readme = "README.md"
-repository = "https://github.com/rust-lang/log"
-documentation = "https://docs.rs/log"
-description = """
-A lightweight logging facade for Rust
-"""
-categories = ["development-tools::debugging"]
-keywords = ["logging"]
-exclude = ["rfcs/**/*", "/.travis.yml", "/appveyor.yml"]
-build = "build.rs"
-
-[package.metadata.docs.rs]
-features = ["std", "serde", "kv_unstable_sval"]
-
-[[test]]
-name = "filters"
-harness = false
-
-[features]
-max_level_off   = []
-max_level_error = []
-max_level_warn  = []
-max_level_info  = []
-max_level_debug = []
-max_level_trace = []
-
-release_max_level_off   = []
-release_max_level_error = []
-release_max_level_warn  = []
-release_max_level_info  = []
-release_max_level_debug = []
-release_max_level_trace = []
-
-std = []
-
-# requires the latest stable
-# this will have a tighter MSRV before stabilization
-kv_unstable = []
-kv_unstable_sval = ["kv_unstable", "sval/fmt"]
-
-[badges]
-travis-ci = { repository = "rust-lang-nursery/log" }
-appveyor = { repository = "alexcrichton/log" }
-
-[dependencies]
-cfg-if = "0.1.2"
-serde = { version = "1.0", optional = true, default-features = false }
-sval = { version = "0.4.2", optional = true, default-features = false }
-
-[dev-dependencies]
-serde_test = "1.0"
-sval = { version = "0.4.2", features = ["test"] }
+[package]

+

+name = "log"

+version = "0.4.11" # remember to update html_root_url

+authors = ["The Rust Project Developers"]

+license = "MIT OR Apache-2.0"

+readme = "README.md"

+repository = "https://github.com/rust-lang/log"

+documentation = "https://docs.rs/log"

+description = """

+A lightweight logging facade for Rust

+"""

+categories = ["development-tools::debugging"]

+keywords = ["logging"]

+exclude = ["rfcs/**/*", "/.travis.yml", "/appveyor.yml"]

+build = "build.rs"

+

+[package.metadata.docs.rs]

+features = ["std", "serde", "kv_unstable_sval"]

+

+[[test]]

+name = "filters"

+harness = false

+

+[[test]]

+name = "macros"

+harness = true

+

+[features]

+max_level_off   = []

+max_level_error = []

+max_level_warn  = []

+max_level_info  = []

+max_level_debug = []

+max_level_trace = []

+

+release_max_level_off   = []

+release_max_level_error = []

+release_max_level_warn  = []

+release_max_level_info  = []

+release_max_level_debug = []

+release_max_level_trace = []

+

+std = []

+

+# requires the latest stable

+# this will have a tighter MSRV before stabilization

+kv_unstable = []

+kv_unstable_sval = ["kv_unstable", "sval/fmt"]

+

+[dependencies]

+cfg-if = "0.1.2"

+serde = { version = "1.0", optional = true, default-features = false }

+sval = { version = "0.5.2", optional = true, default-features = false }

+

+[dev-dependencies]

+serde_test = "1.0"

+sval = { version = "0.5.2", features = ["test"] }

diff --git a/LICENSE-APACHE b/LICENSE-APACHE
index 16fe87b..f47c941 100644
--- a/LICENSE-APACHE
+++ b/LICENSE-APACHE
@@ -1,201 +1,201 @@
-                              Apache License
-                        Version 2.0, January 2004
-                     http://www.apache.org/licenses/
-
-TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
-
-1. Definitions.
-
-   "License" shall mean the terms and conditions for use, reproduction,
-   and distribution as defined by Sections 1 through 9 of this document.
-
-   "Licensor" shall mean the copyright owner or entity authorized by
-   the copyright owner that is granting the License.
-
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-   form, that is based on (or derived from) the Work and for which the
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-   the Work and Derivative Works thereof.
-
-   "Contribution" shall mean any work of authorship, including
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-   to that Work or Derivative Works thereof, that is intentionally
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-   or contributory patent infringement, then any patent licenses
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-
-4. Redistribution. You may reproduce and distribute copies of the
-   Work or Derivative Works thereof in any medium, with or without
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-   meet the following conditions:
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-       Derivative Works a copy of this License; and
-
-   (b) You must cause any modified files to carry prominent notices
-       stating that You changed the files; and
-
-   (c) You must retain, in the Source form of any Derivative Works
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-       do not modify the License. You may add Your own attribution
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-   You may add Your own copyright statement to Your modifications and
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-
-5. Submission of Contributions. Unless You explicitly state otherwise,
-   any Contribution intentionally submitted for inclusion in the Work
-   by You to the Licensor shall be under the terms and conditions of
-   this License, without any additional terms or conditions.
-   Notwithstanding the above, nothing herein shall supersede or modify
-   the terms of any separate license agreement you may have executed
-   with Licensor regarding such Contributions.
-
-6. Trademarks. This License does not grant permission to use the trade
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-   except as required for reasonable and customary use in describing the
-   origin of the Work and reproducing the content of the NOTICE file.
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-7. Disclaimer of Warranty. Unless required by applicable law or
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-   appropriateness of using or redistributing the Work and assume any
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-
-8. Limitation of Liability. In no event and under no legal theory,
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-   incidental, or consequential damages of any character arising as a
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-   has been advised of the possibility of such damages.
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-9. Accepting Warranty or Additional Liability. While redistributing
-   the Work or Derivative Works thereof, You may choose to offer,
-   and charge a fee for, acceptance of support, warranty, indemnity,
-   or other liability obligations and/or rights consistent with this
-   License. However, in accepting such obligations, You may act only
-   on Your own behalf and on Your sole responsibility, not on behalf
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-   defend, and hold each Contributor harmless for any liability
-   incurred by, or claims asserted against, such Contributor by reason
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-END OF TERMS AND CONDITIONS
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-   To apply the Apache License to your work, attach the following
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-Licensed under the Apache License, Version 2.0 (the "License");
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-See the License for the specific language governing permissions and
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+                              Apache License

+                        Version 2.0, January 2004

+                     http://www.apache.org/licenses/

+

+TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

+

+1. Definitions.

+

+   "License" shall mean the terms and conditions for use, reproduction,

+   and distribution as defined by Sections 1 through 9 of this document.

+

+   "Licensor" shall mean the copyright owner or entity authorized by

+   the copyright owner that is granting the License.

+

+   "Legal Entity" shall mean the union of the acting entity and all

+   other entities that control, are controlled by, or are under common

+   control with that entity. For the purposes of this definition,

+   "control" means (i) the power, direct or indirect, to cause the

+   direction or management of such entity, whether by contract or

+   otherwise, or (ii) ownership of fifty percent (50%) or more of the

+   outstanding shares, or (iii) beneficial ownership of such entity.

+

+   "You" (or "Your") shall mean an individual or Legal Entity

+   exercising permissions granted by this License.

+

+   "Source" form shall mean the preferred form for making modifications,

+   including but not limited to software source code, documentation

+   source, and configuration files.

+

+   "Object" form shall mean any form resulting from mechanical

+   transformation or translation of a Source form, including but

+   not limited to compiled object code, generated documentation,

+   and conversions to other media types.

+

+   "Work" shall mean the work of authorship, whether in Source or

+   Object form, made available under the License, as indicated by a

+   copyright notice that is included in or attached to the work

+   (an example is provided in the Appendix below).

+

+   "Derivative Works" shall mean any work, whether in Source or Object

+   form, that is based on (or derived from) the Work and for which the

+   editorial revisions, annotations, elaborations, or other modifications

+   represent, as a whole, an original work of authorship. For the purposes

+   of this License, Derivative Works shall not include works that remain

+   separable from, or merely link (or bind by name) to the interfaces of,

+   the Work and Derivative Works thereof.

+

+   "Contribution" shall mean any work of authorship, including

+   the original version of the Work and any modifications or additions

+   to that Work or Derivative Works thereof, that is intentionally

+   submitted to Licensor for inclusion in the Work by the copyright owner

+   or by an individual or Legal Entity authorized to submit on behalf of

+   the copyright owner. For the purposes of this definition, "submitted"

+   means any form of electronic, verbal, or written communication sent

+   to the Licensor or its representatives, including but not limited to

+   communication on electronic mailing lists, source code control systems,

+   and issue tracking systems that are managed by, or on behalf of, the

+   Licensor for the purpose of discussing and improving the Work, but

+   excluding communication that is conspicuously marked or otherwise

+   designated in writing by the copyright owner as "Not a Contribution."

+

+   "Contributor" shall mean Licensor and any individual or Legal Entity

+   on behalf of whom a Contribution has been received by Licensor and

+   subsequently incorporated within the Work.

+

+2. Grant of Copyright License. Subject to the terms and conditions of

+   this License, each Contributor hereby grants to You a perpetual,

+   worldwide, non-exclusive, no-charge, royalty-free, irrevocable

+   copyright license to reproduce, prepare Derivative Works of,

+   publicly display, publicly perform, sublicense, and distribute the

+   Work and such Derivative Works in Source or Object form.

+

+3. Grant of Patent License. Subject to the terms and conditions of

+   this License, each Contributor hereby grants to You a perpetual,

+   worldwide, non-exclusive, no-charge, royalty-free, irrevocable

+   (except as stated in this section) patent license to make, have made,

+   use, offer to sell, sell, import, and otherwise transfer the Work,

+   where such license applies only to those patent claims licensable

+   by such Contributor that are necessarily infringed by their

+   Contribution(s) alone or by combination of their Contribution(s)

+   with the Work to which such Contribution(s) was submitted. If You

+   institute patent litigation against any entity (including a

+   cross-claim or counterclaim in a lawsuit) alleging that the Work

+   or a Contribution incorporated within the Work constitutes direct

+   or contributory patent infringement, then any patent licenses

+   granted to You under this License for that Work shall terminate

+   as of the date such litigation is filed.

+

+4. Redistribution. You may reproduce and distribute copies of the

+   Work or Derivative Works thereof in any medium, with or without

+   modifications, and in Source or Object form, provided that You

+   meet the following conditions:

+

+   (a) You must give any other recipients of the Work or

+       Derivative Works a copy of this License; and

+

+   (b) You must cause any modified files to carry prominent notices

+       stating that You changed the files; and

+

+   (c) You must retain, in the Source form of any Derivative Works

+       that You distribute, all copyright, patent, trademark, and

+       attribution notices from the Source form of the Work,

+       excluding those notices that do not pertain to any part of

+       the Derivative Works; and

+

+   (d) If the Work includes a "NOTICE" text file as part of its

+       distribution, then any Derivative Works that You distribute must

+       include a readable copy of the attribution notices contained

+       within such NOTICE file, excluding those notices that do not

+       pertain to any part of the Derivative Works, in at least one

+       of the following places: within a NOTICE text file distributed

+       as part of the Derivative Works; within the Source form or

+       documentation, if provided along with the Derivative Works; or,

+       within a display generated by the Derivative Works, if and

+       wherever such third-party notices normally appear. The contents

+       of the NOTICE file are for informational purposes only and

+       do not modify the License. You may add Your own attribution

+       notices within Derivative Works that You distribute, alongside

+       or as an addendum to the NOTICE text from the Work, provided

+       that such additional attribution notices cannot be construed

+       as modifying the License.

+

+   You may add Your own copyright statement to Your modifications and

+   may provide additional or different license terms and conditions

+   for use, reproduction, or distribution of Your modifications, or

+   for any such Derivative Works as a whole, provided Your use,

+   reproduction, and distribution of the Work otherwise complies with

+   the conditions stated in this License.

+

+5. Submission of Contributions. Unless You explicitly state otherwise,

+   any Contribution intentionally submitted for inclusion in the Work

+   by You to the Licensor shall be under the terms and conditions of

+   this License, without any additional terms or conditions.

+   Notwithstanding the above, nothing herein shall supersede or modify

+   the terms of any separate license agreement you may have executed

+   with Licensor regarding such Contributions.

+

+6. Trademarks. This License does not grant permission to use the trade

+   names, trademarks, service marks, or product names of the Licensor,

+   except as required for reasonable and customary use in describing the

+   origin of the Work and reproducing the content of the NOTICE file.

+

+7. Disclaimer of Warranty. Unless required by applicable law or

+   agreed to in writing, Licensor provides the Work (and each

+   Contributor provides its Contributions) on an "AS IS" BASIS,

+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or

+   implied, including, without limitation, any warranties or conditions

+   of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A

+   PARTICULAR PURPOSE. You are solely responsible for determining the

+   appropriateness of using or redistributing the Work and assume any

+   risks associated with Your exercise of permissions under this License.

+

+8. Limitation of Liability. In no event and under no legal theory,

+   whether in tort (including negligence), contract, or otherwise,

+   unless required by applicable law (such as deliberate and grossly

+   negligent acts) or agreed to in writing, shall any Contributor be

+   liable to You for damages, including any direct, indirect, special,

+   incidental, or consequential damages of any character arising as a

+   result of this License or out of the use or inability to use the

+   Work (including but not limited to damages for loss of goodwill,

+   work stoppage, computer failure or malfunction, or any and all

+   other commercial damages or losses), even if such Contributor

+   has been advised of the possibility of such damages.

+

+9. Accepting Warranty or Additional Liability. While redistributing

+   the Work or Derivative Works thereof, You may choose to offer,

+   and charge a fee for, acceptance of support, warranty, indemnity,

+   or other liability obligations and/or rights consistent with this

+   License. However, in accepting such obligations, You may act only

+   on Your own behalf and on Your sole responsibility, not on behalf

+   of any other Contributor, and only if You agree to indemnify,

+   defend, and hold each Contributor harmless for any liability

+   incurred by, or claims asserted against, such Contributor by reason

+   of your accepting any such warranty or additional liability.

+

+END OF TERMS AND CONDITIONS

+

+APPENDIX: How to apply the Apache License to your work.

+

+   To apply the Apache License to your work, attach the following

+   boilerplate notice, with the fields enclosed by brackets "[]"

+   replaced with your own identifying information. (Don't include

+   the brackets!)  The text should be enclosed in the appropriate

+   comment syntax for the file format. We also recommend that a

+   file or class name and description of purpose be included on the

+   same "printed page" as the copyright notice for easier

+   identification within third-party archives.

+

+Copyright [yyyy] [name of copyright owner]

+

+Licensed under the Apache License, Version 2.0 (the "License");

+you may not use this file except in compliance with the License.

+You may obtain a copy of the License at

+

+	http://www.apache.org/licenses/LICENSE-2.0

+

+Unless required by applicable law or agreed to in writing, software

+distributed under the License is distributed on an "AS IS" BASIS,

+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

+See the License for the specific language governing permissions and

+limitations under the License.

diff --git a/LICENSE-MIT b/LICENSE-MIT
index 39d4bdb..c0428e2 100644
--- a/LICENSE-MIT
+++ b/LICENSE-MIT
@@ -1,25 +1,25 @@
-Copyright (c) 2014 The Rust Project Developers
-
-Permission is hereby granted, free of charge, to any
-person obtaining a copy of this software and associated
-documentation files (the "Software"), to deal in the
-Software without restriction, including without
-limitation the rights to use, copy, modify, merge,
-publish, distribute, sublicense, and/or sell copies of
-the Software, and to permit persons to whom the Software
-is furnished to do so, subject to the following
-conditions:
-
-The above copyright notice and this permission notice
-shall be included in all copies or substantial portions
-of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
-ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
-TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
-PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
-SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
-CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
-OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
-IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
-DEALINGS IN THE SOFTWARE.
+Copyright (c) 2014 The Rust Project Developers

+

+Permission is hereby granted, free of charge, to any

+person obtaining a copy of this software and associated

+documentation files (the "Software"), to deal in the

+Software without restriction, including without

+limitation the rights to use, copy, modify, merge,

+publish, distribute, sublicense, and/or sell copies of

+the Software, and to permit persons to whom the Software

+is furnished to do so, subject to the following

+conditions:

+

+The above copyright notice and this permission notice

+shall be included in all copies or substantial portions

+of the Software.

+

+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF

+ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED

+TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A

+PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT

+SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY

+CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION

+OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR

+IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

+DEALINGS IN THE SOFTWARE.

diff --git a/METADATA b/METADATA
index cbed528..10f73fa 100644
--- a/METADATA
+++ b/METADATA
@@ -6,14 +6,14 @@
     value: "https://crates.io/crates/log"
   }
   url {
-    type: GIT
-    value: "https://github.com/rust-lang/log"
+    type: ARCHIVE
+    value: "https://static.crates.io/crates/log/log-0.4.11.crate"
   }
-  version: "0.4.8"
+  version: "0.4.11"
   license_type: NOTICE
   last_upgrade_date {
     year: 2020
-    month: 3
-    day: 31
+    month: 7
+    day: 15
   }
 }
diff --git a/README.md b/README.md
index 5fbcc97..0f87ba7 100644
--- a/README.md
+++ b/README.md
@@ -1,86 +1,86 @@
-log
-===
-
-A Rust library providing a lightweight logging *facade*.
-
-[![Build Status](https://travis-ci.com/rust-lang-nursery/log.svg?branch=master)](https://travis-ci.com/rust-lang-nursery/log)
-[![Build status](https://ci.appveyor.com/api/projects/status/nopdjmmjt45xcrki?svg=true)](https://ci.appveyor.com/project/alexcrichton/log)
-[![Latest version](https://img.shields.io/crates/v/log.svg)](https://crates.io/crates/log)
-[![Documentation](https://docs.rs/log/badge.svg)](https://docs.rs/log)
-![License](https://img.shields.io/crates/l/log.svg)
-
-* [`log` documentation](https://docs.rs/log)
-
-A logging facade provides a single logging API that abstracts over the actual
-logging implementation. Libraries can use the logging API provided by this
-crate, and the consumer of those libraries can choose the logging
-implementation that is most suitable for its use case.
-
-
-## Minimum supported `rustc`
-
-`1.16.0+`
-
-This version is explicitly tested in CI and may be bumped in any release as needed. Maintaining compatibility with older compilers is a priority though, so the bar for bumping the minimum supported version is set very high. Any changes to the supported minimum version will be called out in the release notes.
-
-## Usage
-
-## In libraries
-
-Libraries should link only to the `log` crate, and use the provided macros to
-log whatever information will be useful to downstream consumers:
-
-```toml
-[dependencies]
-log = "0.4"
-```
-
-```rust
-use log::{info, trace, warn};
-
-pub fn shave_the_yak(yak: &mut Yak) {
-    trace!("Commencing yak shaving");
-
-    loop {
-        match find_a_razor() {
-            Ok(razor) => {
-                info!("Razor located: {}", razor);
-                yak.shave(razor);
-                break;
-            }
-            Err(err) => {
-                warn!("Unable to locate a razor: {}, retrying", err);
-            }
-        }
-    }
-}
-```
-
-## In executables
-
-In order to produce log output, executables have to use a logger implementation compatible with the facade.
-There are many available implementations to chose from, here are some of the most popular ones:
-
-* Simple minimal loggers:
-    * [`env_logger`](https://docs.rs/env_logger/*/env_logger/)
-    * [`simple_logger`](https://github.com/borntyping/rust-simple_logger)
-    * [`simplelog`](https://github.com/drakulix/simplelog.rs)
-    * [`pretty_env_logger`](https://docs.rs/pretty_env_logger/*/pretty_env_logger/)
-    * [`stderrlog`](https://docs.rs/stderrlog/*/stderrlog/)
-    * [`flexi_logger`](https://docs.rs/flexi_logger/*/flexi_logger/)
-* Complex configurable frameworks:
-    * [`log4rs`](https://docs.rs/log4rs/*/log4rs/)
-    * [`fern`](https://docs.rs/fern/*/fern/)
-* Adaptors for other facilities:
-    * [`syslog`](https://docs.rs/syslog/*/syslog/)
-    * [`slog-stdlog`](https://docs.rs/slog-stdlog/*/slog_stdlog/)
-    * [`android_log`](https://docs.rs/android_log/*/android_log/)
-* For WebAssembly binaries:
-    * [`console_log`](https://docs.rs/console_log/*/console_log/)
-
-Executables should choose a logger implementation and initialize it early in the
-runtime of the program. Logger implementations will typically include a
-function to do this. Any log messages generated before the logger is
-initialized will be ignored.
-
-The executable itself may use the `log` crate to log as well.
+log

+===

+

+A Rust library providing a lightweight logging *facade*.

+

+[![Build status](https://img.shields.io/github/workflow/status/rust-lang/log/CI/master)](https://github.com/rust-lang/log/actions)

+[![Latest version](https://img.shields.io/crates/v/log.svg)](https://crates.io/crates/log)

+[![Documentation](https://docs.rs/log/badge.svg)](https://docs.rs/log)

+![License](https://img.shields.io/crates/l/log.svg)

+

+* [`log` documentation](https://docs.rs/log)

+

+A logging facade provides a single logging API that abstracts over the actual

+logging implementation. Libraries can use the logging API provided by this

+crate, and the consumer of those libraries can choose the logging

+implementation that is most suitable for its use case.

+

+

+## Minimum supported `rustc`

+

+`1.31.0+`

+

+This version is explicitly tested in CI and may be bumped in any release as needed. Maintaining compatibility with older compilers is a priority though, so the bar for bumping the minimum supported version is set very high. Any changes to the supported minimum version will be called out in the release notes.

+

+## Usage

+

+## In libraries

+

+Libraries should link only to the `log` crate, and use the provided macros to

+log whatever information will be useful to downstream consumers:

+

+```toml

+[dependencies]

+log = "0.4"

+```

+

+```rust

+use log::{info, trace, warn};

+

+pub fn shave_the_yak(yak: &mut Yak) {

+    trace!("Commencing yak shaving");

+

+    loop {

+        match find_a_razor() {

+            Ok(razor) => {

+                info!("Razor located: {}", razor);

+                yak.shave(razor);

+                break;

+            }

+            Err(err) => {

+                warn!("Unable to locate a razor: {}, retrying", err);

+            }

+        }

+    }

+}

+```

+

+## In executables

+

+In order to produce log output, executables have to use a logger implementation compatible with the facade.

+There are many available implementations to choose from, here are some of the most popular ones:

+

+* Simple minimal loggers:

+    * [`env_logger`](https://docs.rs/env_logger/*/env_logger/)

+    * [`simple_logger`](https://github.com/borntyping/rust-simple_logger)

+    * [`simplelog`](https://github.com/drakulix/simplelog.rs)

+    * [`pretty_env_logger`](https://docs.rs/pretty_env_logger/*/pretty_env_logger/)

+    * [`stderrlog`](https://docs.rs/stderrlog/*/stderrlog/)

+    * [`flexi_logger`](https://docs.rs/flexi_logger/*/flexi_logger/)

+* Complex configurable frameworks:

+    * [`log4rs`](https://docs.rs/log4rs/*/log4rs/)

+    * [`fern`](https://docs.rs/fern/*/fern/)

+* Adaptors for other facilities:

+    * [`syslog`](https://docs.rs/syslog/*/syslog/)

+    * [`slog-stdlog`](https://docs.rs/slog-stdlog/*/slog_stdlog/)

+    * [`android_log`](https://docs.rs/android_log/*/android_log/)

+    * [`win_dbg_logger`](https://docs.rs/win_dbg_logger/*/win_dbg_logger/)

+* For WebAssembly binaries:

+    * [`console_log`](https://docs.rs/console_log/*/console_log/)

+

+Executables should choose a logger implementation and initialize it early in the

+runtime of the program. Logger implementations will typically include a

+function to do this. Any log messages generated before the logger is

+initialized will be ignored.

+

+The executable itself may use the `log` crate to log as well.

diff --git a/build.rs b/build.rs
index 6717bf0..65d2398 100644
--- a/build.rs
+++ b/build.rs
@@ -1,14 +1,14 @@
-//! This build script detects target platforms that lack proper support for
-//! atomics and sets `cfg` flags accordingly.
-
-use std::env;
-
-fn main() {
-    let target = env::var("TARGET").unwrap();
-
-    if !target.starts_with("thumbv6") {
-        println!("cargo:rustc-cfg=atomic_cas");
-    }
-
-    println!("cargo:rerun-if-changed=build.rs");
-}
+//! This build script detects target platforms that lack proper support for

+//! atomics and sets `cfg` flags accordingly.

+

+use std::env;

+

+fn main() {

+    let target = env::var("TARGET").unwrap();

+

+    if !target.starts_with("thumbv6") {

+        println!("cargo:rustc-cfg=atomic_cas");

+    }

+

+    println!("cargo:rerun-if-changed=build.rs");

+}

diff --git a/src/kv/error.rs b/src/kv/error.rs
index 0f5652f..f68f2da 100644
--- a/src/kv/error.rs
+++ b/src/kv/error.rs
@@ -1,88 +1,70 @@
-use std::fmt;
-
-/// An error encountered while working with structured data.
-#[derive(Debug)]
-pub struct Error {
-    inner: Inner
-}
-
-#[derive(Debug)]
-enum Inner {
-    #[cfg(feature = "std")]
-    Boxed(std_support::BoxedError),
-    Msg(&'static str),
-    Fmt,
-}
-
-impl Error {
-    /// Create an error from a message.
-    pub fn msg(msg: &'static str) -> Self {
-        Error {
-            inner: Inner::Msg(msg),
-        }
-    }
-}
-
-impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        use self::Inner::*;
-        match &self.inner {
-            #[cfg(feature = "std")]
-            &Boxed(ref err) => err.fmt(f),
-            &Msg(ref msg) => msg.fmt(f),
-            &Fmt => fmt::Error.fmt(f),
-        }
-    }
-}
-
-impl From<fmt::Error> for Error {
-    fn from(_: fmt::Error) -> Self {
-        Error {
-            inner: Inner::Fmt,
-        }
-    }
-}
-
-impl From<Error> for fmt::Error {
-    fn from(_: Error) -> Self {
-        fmt::Error
-    }
-}
-
-#[cfg(feature = "std")]
-mod std_support {
-    use super::*;
-    use std::{error, io};
-
-    pub(super) type BoxedError = Box<error::Error + Send + Sync>;
-
-    impl Error {
-        /// Create an error from a standard error type.
-        pub fn boxed<E>(err: E) -> Self
-        where
-            E: Into<BoxedError>,
-        {
-            Error {
-                inner: Inner::Boxed(err.into())
-            }
-        }
-    }
-
-    impl error::Error for Error {
-        fn description(&self) -> &str {
-            "key values error"
-        }
-    }
-
-    impl From<io::Error> for Error {
-        fn from(err: io::Error) -> Self {
-            Error::boxed(err)
-        }
-    }
-
-    impl From<Error> for io::Error {
-        fn from(err: Error) -> Self {
-            io::Error::new(io::ErrorKind::Other, err)
-        }
-    }
-}
+use std::fmt;

+

+/// An error encountered while working with structured data.

+#[derive(Debug)]

+pub struct Error {

+    inner: Inner,

+}

+

+#[derive(Debug)]

+enum Inner {

+    #[cfg(feature = "std")]

+    Boxed(std_support::BoxedError),

+    Msg(&'static str),

+    Fmt,

+}

+

+impl Error {

+    /// Create an error from a message.

+    pub fn msg(msg: &'static str) -> Self {

+        Error {

+            inner: Inner::Msg(msg),

+        }

+    }

+}

+

+impl fmt::Display for Error {

+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

+        use self::Inner::*;

+        match &self.inner {

+            #[cfg(feature = "std")]

+            &Boxed(ref err) => err.fmt(f),

+            &Msg(ref msg) => msg.fmt(f),

+            &Fmt => fmt::Error.fmt(f),

+        }

+    }

+}

+

+impl From<fmt::Error> for Error {

+    fn from(_: fmt::Error) -> Self {

+        Error { inner: Inner::Fmt }

+    }

+}

+

+#[cfg(feature = "std")]

+mod std_support {

+    use super::*;

+    use std::{error, io};

+

+    pub(super) type BoxedError = Box<dyn error::Error + Send + Sync>;

+

+    impl Error {

+        /// Create an error from a standard error type.

+        pub fn boxed<E>(err: E) -> Self

+        where

+            E: Into<BoxedError>,

+        {

+            Error {

+                inner: Inner::Boxed(err.into()),

+            }

+        }

+    }

+

+    impl error::Error for Error {}

+

+    impl From<io::Error> for Error {

+        fn from(err: io::Error) -> Self {

+            Error::boxed(err)

+        }

+    }

+}

diff --git a/src/kv/key.rs b/src/kv/key.rs
index 82f1e85..367f6ed 100644
--- a/src/kv/key.rs
+++ b/src/kv/key.rs
@@ -1,143 +1,139 @@
-//! Structured keys.
-
-use std::fmt;
-use std::cmp;
-use std::hash;
-use std::borrow::Borrow;
-
-/// A type that can be converted into a [`Key`](struct.Key.html).
-pub trait ToKey {
-    /// Perform the conversion.
-    fn to_key(&self) -> Key;
-}
-
-impl<'a, T> ToKey for &'a T
-where
-    T: ToKey + ?Sized,
-{
-    fn to_key(&self) -> Key {
-        (**self).to_key()
-    }
-}
-
-impl<'k> ToKey for Key<'k> {
-    fn to_key(&self) -> Key {
-        Key {
-            key: self.key,
-        }
-    }
-}
-
-impl ToKey for str {
-    fn to_key(&self) -> Key {
-        Key::from_str(self)
-    }
-}
-
-/// A key in a structured key-value pair.
-#[derive(Clone)]
-pub struct Key<'k> {
-    key: &'k str,
-}
-
-impl<'k> Key<'k> {
-    /// Get a key from a borrowed string.
-    pub fn from_str(key: &'k str) -> Self {
-        Key {
-            key: key,
-        }
-    }
-
-    /// Get a borrowed string from this key.
-    pub fn as_str(&self) -> &str {
-        self.key
-    }
-}
-
-impl<'k> fmt::Debug for Key<'k> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.key.fmt(f)
-    }
-}
-
-impl<'k> fmt::Display for Key<'k> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.key.fmt(f)
-    }
-}
-
-impl<'k> hash::Hash for Key<'k> {
-    fn hash<H>(&self, state: &mut H)
-    where
-        H: hash::Hasher,
-    {
-        self.as_str().hash(state)
-    }
-}
-
-impl<'k, 'ko> PartialEq<Key<'ko>> for Key<'k> {
-    fn eq(&self, other: &Key<'ko>) -> bool {
-        self.as_str().eq(other.as_str())
-    }
-}
-
-impl<'k> Eq for Key<'k> {}
-
-impl<'k, 'ko> PartialOrd<Key<'ko>> for Key<'k> {
-    fn partial_cmp(&self, other: &Key<'ko>) -> Option<cmp::Ordering> {
-        self.as_str().partial_cmp(other.as_str())
-    }
-}
-
-impl<'k> Ord for Key<'k> {
-    fn cmp(&self, other: &Self) -> cmp::Ordering {
-        self.as_str().cmp(other.as_str())
-    }
-}
-
-impl<'k> AsRef<str> for Key<'k> {
-    fn as_ref(&self) -> &str {
-        self.as_str()
-    }
-}
-
-impl<'k> Borrow<str> for Key<'k> {
-    fn borrow(&self) -> &str {
-        self.as_str()
-    }
-}
-
-impl<'k> From<&'k str> for Key<'k> {
-    fn from(s: &'k str) -> Self {
-        Key::from_str(s)
-    }
-}
-
-#[cfg(feature = "std")]
-mod std_support {
-    use super::*;
-
-    use std::borrow::Cow;
-
-    impl ToKey for String {
-        fn to_key(&self) -> Key {
-            Key::from_str(self)
-        }
-    }
-
-    impl<'a> ToKey for Cow<'a, str> {
-        fn to_key(&self) -> Key {
-            Key::from_str(self)
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn key_from_string() {
-        assert_eq!("a key", Key::from_str("a key").as_str());
-    }
-}
+//! Structured keys.

+

+use std::borrow::Borrow;

+use std::cmp;

+use std::fmt;

+use std::hash;

+

+/// A type that can be converted into a [`Key`](struct.Key.html).

+pub trait ToKey {

+    /// Perform the conversion.

+    fn to_key(&self) -> Key;

+}

+

+impl<'a, T> ToKey for &'a T

+where

+    T: ToKey + ?Sized,

+{

+    fn to_key(&self) -> Key {

+        (**self).to_key()

+    }

+}

+

+impl<'k> ToKey for Key<'k> {

+    fn to_key(&self) -> Key {

+        Key { key: self.key }

+    }

+}

+

+impl ToKey for str {

+    fn to_key(&self) -> Key {

+        Key::from_str(self)

+    }

+}

+

+/// A key in a structured key-value pair.

+#[derive(Clone)]

+pub struct Key<'k> {

+    key: &'k str,

+}

+

+impl<'k> Key<'k> {

+    /// Get a key from a borrowed string.

+    pub fn from_str(key: &'k str) -> Self {

+        Key { key: key }

+    }

+

+    /// Get a borrowed string from this key.

+    pub fn as_str(&self) -> &str {

+        self.key

+    }

+}

+

+impl<'k> fmt::Debug for Key<'k> {

+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

+        self.key.fmt(f)

+    }

+}

+

+impl<'k> fmt::Display for Key<'k> {

+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

+        self.key.fmt(f)

+    }

+}

+

+impl<'k> hash::Hash for Key<'k> {

+    fn hash<H>(&self, state: &mut H)

+    where

+        H: hash::Hasher,

+    {

+        self.as_str().hash(state)

+    }

+}

+

+impl<'k, 'ko> PartialEq<Key<'ko>> for Key<'k> {

+    fn eq(&self, other: &Key<'ko>) -> bool {

+        self.as_str().eq(other.as_str())

+    }

+}

+

+impl<'k> Eq for Key<'k> {}

+

+impl<'k, 'ko> PartialOrd<Key<'ko>> for Key<'k> {

+    fn partial_cmp(&self, other: &Key<'ko>) -> Option<cmp::Ordering> {

+        self.as_str().partial_cmp(other.as_str())

+    }

+}

+

+impl<'k> Ord for Key<'k> {

+    fn cmp(&self, other: &Self) -> cmp::Ordering {

+        self.as_str().cmp(other.as_str())

+    }

+}

+

+impl<'k> AsRef<str> for Key<'k> {

+    fn as_ref(&self) -> &str {

+        self.as_str()

+    }

+}

+

+impl<'k> Borrow<str> for Key<'k> {

+    fn borrow(&self) -> &str {

+        self.as_str()

+    }

+}

+

+impl<'k> From<&'k str> for Key<'k> {

+    fn from(s: &'k str) -> Self {

+        Key::from_str(s)

+    }

+}

+

+#[cfg(feature = "std")]

+mod std_support {

+    use super::*;

+

+    use std::borrow::Cow;

+

+    impl ToKey for String {

+        fn to_key(&self) -> Key {

+            Key::from_str(self)

+        }

+    }

+

+    impl<'a> ToKey for Cow<'a, str> {

+        fn to_key(&self) -> Key {

+            Key::from_str(self)

+        }

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    use super::*;

+

+    #[test]

+    fn key_from_string() {

+        assert_eq!("a key", Key::from_str("a key").as_str());

+    }

+}

diff --git a/src/kv/mod.rs b/src/kv/mod.rs
index 17226b4..f4c0866 100644
--- a/src/kv/mod.rs
+++ b/src/kv/mod.rs
@@ -1,23 +1,26 @@
-//! **UNSTABLE:** Structured key-value pairs.
-//! 
-//! This module is unstable and breaking changes may be made
-//! at any time. See [the tracking issue](https://github.com/rust-lang-nursery/log/issues/328)
-//! for more details.
-//! 
-//! Add the `kv_unstable` feature to your `Cargo.toml` to enable
-//! this module:
-//! 
-//! ```toml
-//! [dependencies.log]
-//! features = ["kv_unstable"]
-//! ```
-
-mod error;
-mod source;
-mod key;
-pub mod value;
-
-pub use self::error::Error;
-pub use self::source::{Source, Visitor};
-pub use self::key::{Key, ToKey};
-pub use self::value::{Value, ToValue};
+//! **UNSTABLE:** Structured key-value pairs.

+//!

+//! This module is unstable and breaking changes may be made

+//! at any time. See [the tracking issue](https://github.com/rust-lang-nursery/log/issues/328)

+//! for more details.

+//!

+//! Add the `kv_unstable` feature to your `Cargo.toml` to enable

+//! this module:

+//!

+//! ```toml

+//! [dependencies.log]

+//! features = ["kv_unstable"]

+//! ```

+

+mod error;

+mod key;

+mod source;

+

+pub mod value;

+

+pub use self::error::Error;

+pub use self::key::{Key, ToKey};

+pub use self::source::{Source, Visitor};

+

+#[doc(inline)]

+pub use self::value::{ToValue, Value};

diff --git a/src/kv/source.rs b/src/kv/source.rs
index 0538c14..eeac1ec 100644
--- a/src/kv/source.rs
+++ b/src/kv/source.rs
@@ -1,396 +1,393 @@
-//! Sources for key-value pairs.
-
-use std::fmt;
-use kv::{Error, Key, ToKey, Value, ToValue};
-
-/// A source of key-value pairs.
-///
-/// The source may be a single pair, a set of pairs, or a filter over a set of pairs.
-/// Use the [`Visitor`](trait.Visitor.html) trait to inspect the structured data
-/// in a source.
-pub trait Source {
-    /// Visit key-value pairs.
-    ///
-    /// A source doesn't have to guarantee any ordering or uniqueness of key-value pairs.
-    /// If the given visitor returns an error then the source may early-return with it,
-    /// even if there are more key-value pairs.
-    ///
-    /// # Implementation notes
-    ///
-    /// A source should yield the same key-value pairs to a subsequent visitor unless
-    /// that visitor itself fails.
-    fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error>;
-
-    /// Get the value for a given key.
-    /// 
-    /// If the key appears multiple times in the source then which key is returned
-    /// is implementation specific.
-    ///
-    /// # Implementation notes
-    ///
-    /// A source that can provide a more efficient implementation of this method
-    /// should override it.
-    fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {
-        struct Get<'k, 'v> {
-            key: Key<'k>,
-            found: Option<Value<'v>>,
-        }
-
-        impl<'k, 'kvs> Visitor<'kvs> for Get<'k, 'kvs> {
-            fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {
-                if self.key == key {
-                    self.found = Some(value);
-                }
-
-                Ok(())
-            }
-        }
-
-        let mut get = Get {
-            key,
-            found: None,
-        };
-
-        let _ = self.visit(&mut get);
-        get.found
-    }
-
-    /// Count the number of key-value pairs that can be visited.
-    ///
-    /// # Implementation notes
-    ///
-    /// A source that knows the number of key-value pairs upfront may provide a more
-    /// efficient implementation.
-    ///
-    /// A subsequent call to `visit` should yield the same number of key-value pairs
-    /// to the visitor, unless that visitor fails part way through.
-    fn count(&self) -> usize {
-        struct Count(usize);
-
-        impl<'kvs> Visitor<'kvs> for Count {
-            fn visit_pair(&mut self, _: Key<'kvs>, _: Value<'kvs>) -> Result<(), Error> {
-                self.0 += 1;
-
-                Ok(())
-            }
-        }
-
-        let mut count = Count(0);
-        let _ = self.visit(&mut count);
-        count.0
-    }
-}
-
-impl<'a, T> Source for &'a T
-where
-    T: Source + ?Sized,
-{
-    fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-        Source::visit(&**self, visitor)
-    }
-
-    fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {
-        Source::get(&**self, key)
-    }
-
-    fn count(&self) -> usize {
-        Source::count(&**self)
-    }
-}
-
-impl<K, V> Source for (K, V)
-where
-    K: ToKey,
-    V: ToValue,
-{
-    fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-        visitor.visit_pair(self.0.to_key(), self.1.to_value())
-    }
-
-    fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {
-        if self.0.to_key() == key {
-            Some(self.1.to_value())
-        } else {
-            None
-        }
-    }
-
-    fn count(&self) -> usize {
-        1
-    }
-}
-
-impl<S> Source for [S]
-where
-    S: Source,
-{
-    fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-        for source in self {
-            source.visit(visitor)?;
-        }
-
-        Ok(())
-    }
-
-    fn count(&self) -> usize {
-        self.len()
-    }
-}
-
-impl<S> Source for Option<S>
-where
-    S: Source,
-{
-    fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-        if let Some(ref source) = *self {
-            source.visit(visitor)?;
-        }
-
-        Ok(())
-    }
-
-    fn count(&self) -> usize {
-        self.as_ref().map(Source::count).unwrap_or(0)
-    }
-}
-
-/// A visitor for the key-value pairs in a [`Source`](trait.Source.html).
-pub trait Visitor<'kvs> {
-    /// Visit a key-value pair.
-    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error>;
-}
-
-impl<'a, 'kvs, T> Visitor<'kvs> for &'a mut T
-where
-    T: Visitor<'kvs> + ?Sized,
-{
-    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {
-        (**self).visit_pair(key, value)
-    }
-}
-
-impl<'a, 'b: 'a, 'kvs> Visitor<'kvs> for fmt::DebugMap<'a, 'b> {
-    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {
-        self.entry(&key, &value);
-        Ok(())
-    }
-}
-
-impl<'a, 'b: 'a, 'kvs> Visitor<'kvs> for fmt::DebugList<'a, 'b> {
-    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {
-        self.entry(&(key, value));
-        Ok(())
-    }
-}
-
-impl<'a, 'b: 'a, 'kvs> Visitor<'kvs> for fmt::DebugSet<'a, 'b> {
-    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {
-        self.entry(&(key, value));
-        Ok(())
-    }
-}
-
-impl<'a, 'b: 'a, 'kvs> Visitor<'kvs> for fmt::DebugTuple<'a, 'b> {
-    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {
-        self.field(&key);
-        self.field(&value);
-        Ok(())
-    }
-}
-
-#[cfg(feature = "std")]
-mod std_support {
-    use super::*;
-    use std::borrow::Borrow;
-    use std::collections::{BTreeMap, HashMap};
-    use std::hash::{BuildHasher, Hash};
-
-    impl<S> Source for Box<S>
-    where
-        S: Source + ?Sized,
-    {
-        fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-            Source::visit(&**self, visitor)
-        }
-
-        fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {
-            Source::get(&**self, key)
-        }
-
-        fn count(&self) -> usize {
-            Source::count(&**self)
-        }
-    }
-
-    impl<S> Source for Vec<S>
-    where
-        S: Source,
-    {
-        fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-            Source::visit(&**self, visitor)
-        }
-
-        fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {
-            Source::get(&**self, key)
-        }
-
-        fn count(&self) -> usize {
-            Source::count(&**self)
-        }
-    }
-
-    impl<'kvs, V> Visitor<'kvs> for Box<V>
-    where
-        V: Visitor<'kvs> + ?Sized,
-    {
-        fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {
-            (**self).visit_pair(key, value)
-        }
-    }
-
-    impl<K, V, S> Source for HashMap<K, V, S>
-    where
-        K: ToKey + Borrow<str> + Eq + Hash,
-        V: ToValue,
-        S: BuildHasher,
-    {
-        fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-            for (key, value) in self {
-                visitor.visit_pair(key.to_key(), value.to_value())?;
-            }
-            Ok(())
-        }
-
-        fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {
-            HashMap::get(self, key.as_str()).map(|v| v.to_value())
-        }
-
-        fn count(&self) -> usize {
-            self.len()
-        }
-    }
-
-    impl<K, V> Source for BTreeMap<K, V>
-    where
-        K: ToKey + Borrow<str> + Ord,
-        V: ToValue,
-    {
-        fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-            for (key, value) in self {
-                visitor.visit_pair(key.to_key(), value.to_value())?;
-            }
-            Ok(())
-        }
-
-        fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {
-            BTreeMap::get(self, key.as_str()).map(|v| v.to_value())
-        }
-
-        fn count(&self) -> usize {
-            self.len()
-        }
-    }
-
-    #[cfg(test)]
-    mod tests {
-        use super::*;
-        use kv::value::test::Token;
-        use std::collections::{BTreeMap, HashMap};
-
-        #[test]
-        fn count() {
-            assert_eq!(1, Source::count(&Box::new(("a", 1))));
-            assert_eq!(2, Source::count(&vec![("a", 1), ("b", 2)]));
-        }
-
-        #[test]
-        fn get() {
-            let source = vec![("a", 1), ("b", 2), ("a", 1)];
-            assert_eq!(
-                Token::I64(1),
-                Source::get(&source, Key::from_str("a")).unwrap().to_token()
-            );
-
-            let source = Box::new(Option::None::<(&str, i32)>);
-            assert!(Source::get(&source, Key::from_str("a")).is_none());
-        }
-
-        #[test]
-        fn hash_map() {
-            let mut map = HashMap::new();
-            map.insert("a", 1);
-            map.insert("b", 2);
-
-            assert_eq!(2, Source::count(&map));
-            assert_eq!(
-                Token::I64(1),
-                Source::get(&map, Key::from_str("a")).unwrap().to_token()
-            );
-        }
-
-        #[test]
-        fn btree_map() {
-            let mut map = BTreeMap::new();
-            map.insert("a", 1);
-            map.insert("b", 2);
-
-            assert_eq!(2, Source::count(&map));
-            assert_eq!(
-                Token::I64(1),
-                Source::get(&map, Key::from_str("a")).unwrap().to_token()
-            );
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use kv::value::test::Token;
-
-    #[test]
-    fn source_is_object_safe() {
-        fn _check(_: &Source) {}
-    }
-
-    #[test]
-    fn visitor_is_object_safe() {
-        fn _check(_: &Visitor) {}
-    }
-
-    #[test]
-    fn count() {
-        struct OnePair {
-            key: &'static str,
-            value: i32,
-        }
-
-        impl Source for OnePair {
-            fn visit<'kvs>(&'kvs self, visitor: &mut Visitor<'kvs>) -> Result<(), Error> {
-                visitor.visit_pair(self.key.to_key(), self.value.to_value())
-            }
-        }
-
-        assert_eq!(1, Source::count(&("a", 1)));
-        assert_eq!(2, Source::count(&[("a", 1), ("b", 2)] as &[_]));
-        assert_eq!(0, Source::count(&Option::None::<(&str, i32)>));
-        assert_eq!(1, Source::count(&OnePair { key: "a", value: 1 }));
-    }
-
-    #[test]
-    fn get() {
-        let source = &[("a", 1), ("b", 2), ("a", 1)] as &[_];
-        assert_eq!(
-            Token::I64(1),
-            Source::get(source, Key::from_str("a")).unwrap().to_token()
-        );
-        assert_eq!(
-            Token::I64(2),
-            Source::get(source, Key::from_str("b")).unwrap().to_token()
-        );
-        assert!(Source::get(&source, Key::from_str("c")).is_none());
-
-        let source = Option::None::<(&str, i32)>;
-        assert!(Source::get(&source, Key::from_str("a")).is_none());
-    }
-}
+//! Sources for key-value pairs.

+

+use kv::{Error, Key, ToKey, ToValue, Value};

+use std::fmt;

+

+/// A source of key-value pairs.

+///

+/// The source may be a single pair, a set of pairs, or a filter over a set of pairs.

+/// Use the [`Visitor`](trait.Visitor.html) trait to inspect the structured data

+/// in a source.

+pub trait Source {

+    /// Visit key-value pairs.

+    ///

+    /// A source doesn't have to guarantee any ordering or uniqueness of key-value pairs.

+    /// If the given visitor returns an error then the source may early-return with it,

+    /// even if there are more key-value pairs.

+    ///

+    /// # Implementation notes

+    ///

+    /// A source should yield the same key-value pairs to a subsequent visitor unless

+    /// that visitor itself fails.

+    fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error>;

+

+    /// Get the value for a given key.

+    ///

+    /// If the key appears multiple times in the source then which key is returned

+    /// is implementation specific.

+    ///

+    /// # Implementation notes

+    ///

+    /// A source that can provide a more efficient implementation of this method

+    /// should override it.

+    fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {

+        struct Get<'k, 'v> {

+            key: Key<'k>,

+            found: Option<Value<'v>>,

+        }

+

+        impl<'k, 'kvs> Visitor<'kvs> for Get<'k, 'kvs> {

+            fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {

+                if self.key == key {

+                    self.found = Some(value);

+                }

+

+                Ok(())

+            }

+        }

+

+        let mut get = Get { key, found: None };

+

+        let _ = self.visit(&mut get);

+        get.found

+    }

+

+    /// Count the number of key-value pairs that can be visited.

+    ///

+    /// # Implementation notes

+    ///

+    /// A source that knows the number of key-value pairs upfront may provide a more

+    /// efficient implementation.

+    ///

+    /// A subsequent call to `visit` should yield the same number of key-value pairs

+    /// to the visitor, unless that visitor fails part way through.

+    fn count(&self) -> usize {

+        struct Count(usize);

+

+        impl<'kvs> Visitor<'kvs> for Count {

+            fn visit_pair(&mut self, _: Key<'kvs>, _: Value<'kvs>) -> Result<(), Error> {

+                self.0 += 1;

+

+                Ok(())

+            }

+        }

+

+        let mut count = Count(0);

+        let _ = self.visit(&mut count);

+        count.0

+    }

+}

+

+impl<'a, T> Source for &'a T

+where

+    T: Source + ?Sized,

+{

+    fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+        Source::visit(&**self, visitor)

+    }

+

+    fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {

+        Source::get(&**self, key)

+    }

+

+    fn count(&self) -> usize {

+        Source::count(&**self)

+    }

+}

+

+impl<K, V> Source for (K, V)

+where

+    K: ToKey,

+    V: ToValue,

+{

+    fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+        visitor.visit_pair(self.0.to_key(), self.1.to_value())

+    }

+

+    fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {

+        if self.0.to_key() == key {

+            Some(self.1.to_value())

+        } else {

+            None

+        }

+    }

+

+    fn count(&self) -> usize {

+        1

+    }

+}

+

+impl<S> Source for [S]

+where

+    S: Source,

+{

+    fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+        for source in self {

+            source.visit(visitor)?;

+        }

+

+        Ok(())

+    }

+

+    fn count(&self) -> usize {

+        self.len()

+    }

+}

+

+impl<S> Source for Option<S>

+where

+    S: Source,

+{

+    fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+        if let Some(ref source) = *self {

+            source.visit(visitor)?;

+        }

+

+        Ok(())

+    }

+

+    fn count(&self) -> usize {

+        self.as_ref().map(Source::count).unwrap_or(0)

+    }

+}

+

+/// A visitor for the key-value pairs in a [`Source`](trait.Source.html).

+pub trait Visitor<'kvs> {

+    /// Visit a key-value pair.

+    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error>;

+}

+

+impl<'a, 'kvs, T> Visitor<'kvs> for &'a mut T

+where

+    T: Visitor<'kvs> + ?Sized,

+{

+    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {

+        (**self).visit_pair(key, value)

+    }

+}

+

+impl<'a, 'b: 'a, 'kvs> Visitor<'kvs> for fmt::DebugMap<'a, 'b> {

+    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {

+        self.entry(&key, &value);

+        Ok(())

+    }

+}

+

+impl<'a, 'b: 'a, 'kvs> Visitor<'kvs> for fmt::DebugList<'a, 'b> {

+    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {

+        self.entry(&(key, value));

+        Ok(())

+    }

+}

+

+impl<'a, 'b: 'a, 'kvs> Visitor<'kvs> for fmt::DebugSet<'a, 'b> {

+    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {

+        self.entry(&(key, value));

+        Ok(())

+    }

+}

+

+impl<'a, 'b: 'a, 'kvs> Visitor<'kvs> for fmt::DebugTuple<'a, 'b> {

+    fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {

+        self.field(&key);

+        self.field(&value);

+        Ok(())

+    }

+}

+

+#[cfg(feature = "std")]

+mod std_support {

+    use super::*;

+    use std::borrow::Borrow;

+    use std::collections::{BTreeMap, HashMap};

+    use std::hash::{BuildHasher, Hash};

+

+    impl<S> Source for Box<S>

+    where

+        S: Source + ?Sized,

+    {

+        fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+            Source::visit(&**self, visitor)

+        }

+

+        fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {

+            Source::get(&**self, key)

+        }

+

+        fn count(&self) -> usize {

+            Source::count(&**self)

+        }

+    }

+

+    impl<S> Source for Vec<S>

+    where

+        S: Source,

+    {

+        fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+            Source::visit(&**self, visitor)

+        }

+

+        fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {

+            Source::get(&**self, key)

+        }

+

+        fn count(&self) -> usize {

+            Source::count(&**self)

+        }

+    }

+

+    impl<'kvs, V> Visitor<'kvs> for Box<V>

+    where

+        V: Visitor<'kvs> + ?Sized,

+    {

+        fn visit_pair(&mut self, key: Key<'kvs>, value: Value<'kvs>) -> Result<(), Error> {

+            (**self).visit_pair(key, value)

+        }

+    }

+

+    impl<K, V, S> Source for HashMap<K, V, S>

+    where

+        K: ToKey + Borrow<str> + Eq + Hash,

+        V: ToValue,

+        S: BuildHasher,

+    {

+        fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+            for (key, value) in self {

+                visitor.visit_pair(key.to_key(), value.to_value())?;

+            }

+            Ok(())

+        }

+

+        fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {

+            HashMap::get(self, key.as_str()).map(|v| v.to_value())

+        }

+

+        fn count(&self) -> usize {

+            self.len()

+        }

+    }

+

+    impl<K, V> Source for BTreeMap<K, V>

+    where

+        K: ToKey + Borrow<str> + Ord,

+        V: ToValue,

+    {

+        fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+            for (key, value) in self {

+                visitor.visit_pair(key.to_key(), value.to_value())?;

+            }

+            Ok(())

+        }

+

+        fn get<'v>(&'v self, key: Key) -> Option<Value<'v>> {

+            BTreeMap::get(self, key.as_str()).map(|v| v.to_value())

+        }

+

+        fn count(&self) -> usize {

+            self.len()

+        }

+    }

+

+    #[cfg(test)]

+    mod tests {

+        use super::*;

+        use kv::value::test::Token;

+        use std::collections::{BTreeMap, HashMap};

+

+        #[test]

+        fn count() {

+            assert_eq!(1, Source::count(&Box::new(("a", 1))));

+            assert_eq!(2, Source::count(&vec![("a", 1), ("b", 2)]));

+        }

+

+        #[test]

+        fn get() {

+            let source = vec![("a", 1), ("b", 2), ("a", 1)];

+            assert_eq!(

+                Token::I64(1),

+                Source::get(&source, Key::from_str("a")).unwrap().to_token()

+            );

+

+            let source = Box::new(Option::None::<(&str, i32)>);

+            assert!(Source::get(&source, Key::from_str("a")).is_none());

+        }

+

+        #[test]

+        fn hash_map() {

+            let mut map = HashMap::new();

+            map.insert("a", 1);

+            map.insert("b", 2);

+

+            assert_eq!(2, Source::count(&map));

+            assert_eq!(

+                Token::I64(1),

+                Source::get(&map, Key::from_str("a")).unwrap().to_token()

+            );

+        }

+

+        #[test]

+        fn btree_map() {

+            let mut map = BTreeMap::new();

+            map.insert("a", 1);

+            map.insert("b", 2);

+

+            assert_eq!(2, Source::count(&map));

+            assert_eq!(

+                Token::I64(1),

+                Source::get(&map, Key::from_str("a")).unwrap().to_token()

+            );

+        }

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    use super::*;

+    use kv::value::test::Token;

+

+    #[test]

+    fn source_is_object_safe() {

+        fn _check(_: &dyn Source) {}

+    }

+

+    #[test]

+    fn visitor_is_object_safe() {

+        fn _check(_: &dyn Visitor) {}

+    }

+

+    #[test]

+    fn count() {

+        struct OnePair {

+            key: &'static str,

+            value: i32,

+        }

+

+        impl Source for OnePair {

+            fn visit<'kvs>(&'kvs self, visitor: &mut dyn Visitor<'kvs>) -> Result<(), Error> {

+                visitor.visit_pair(self.key.to_key(), self.value.to_value())

+            }

+        }

+

+        assert_eq!(1, Source::count(&("a", 1)));

+        assert_eq!(2, Source::count(&[("a", 1), ("b", 2)] as &[_]));

+        assert_eq!(0, Source::count(&Option::None::<(&str, i32)>));

+        assert_eq!(1, Source::count(&OnePair { key: "a", value: 1 }));

+    }

+

+    #[test]

+    fn get() {

+        let source = &[("a", 1), ("b", 2), ("a", 1)] as &[_];

+        assert_eq!(

+            Token::I64(1),

+            Source::get(source, Key::from_str("a")).unwrap().to_token()

+        );

+        assert_eq!(

+            Token::I64(2),

+            Source::get(source, Key::from_str("b")).unwrap().to_token()

+        );

+        assert!(Source::get(&source, Key::from_str("c")).is_none());

+

+        let source = Option::None::<(&str, i32)>;

+        assert!(Source::get(&source, Key::from_str("a")).is_none());

+    }

+}

diff --git a/src/kv/value/fill.rs b/src/kv/value/fill.rs
new file mode 100644
index 0000000..2e74899
--- /dev/null
+++ b/src/kv/value/fill.rs
@@ -0,0 +1,164 @@
+//! Lazy value initialization.

+

+use std::fmt;

+

+use super::internal::{Erased, Inner, Visitor};

+use super::{Error, Value};

+

+impl<'v> Value<'v> {

+    /// Get a value from a fillable slot.

+    pub fn from_fill<T>(value: &'v T) -> Self

+    where

+        T: Fill + 'static,

+    {

+        Value {

+            inner: Inner::Fill(unsafe { Erased::new_unchecked::<T>(value) }),

+        }

+    }

+}

+

+/// A type that requires extra work to convert into a [`Value`](struct.Value.html).

+///

+/// This trait is a more advanced initialization API than [`ToValue`](trait.ToValue.html).

+/// It's intended for erased values coming from other logging frameworks that may need

+/// to perform extra work to determine the concrete type to use.

+pub trait Fill {

+    /// Fill a value.

+    fn fill(&self, slot: &mut Slot) -> Result<(), Error>;

+}

+

+impl<'a, T> Fill for &'a T

+where

+    T: Fill + ?Sized,

+{

+    fn fill(&self, slot: &mut Slot) -> Result<(), Error> {

+        (**self).fill(slot)

+    }

+}

+

+/// A value slot to fill using the [`Fill`](trait.Fill.html) trait.

+pub struct Slot<'s, 'f> {

+    filled: bool,

+    visitor: &'s mut dyn Visitor<'f>,

+}

+

+impl<'s, 'f> fmt::Debug for Slot<'s, 'f> {

+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

+        f.debug_struct("Slot").finish()

+    }

+}

+

+impl<'s, 'f> Slot<'s, 'f> {

+    pub(super) fn new(visitor: &'s mut dyn Visitor<'f>) -> Self {

+        Slot {

+            visitor,

+            filled: false,

+        }

+    }

+

+    pub(super) fn fill<F>(&mut self, f: F) -> Result<(), Error>

+    where

+        F: FnOnce(&mut dyn Visitor<'f>) -> Result<(), Error>,

+    {

+        assert!(!self.filled, "the slot has already been filled");

+        self.filled = true;

+

+        f(self.visitor)

+    }

+

+    /// Fill the slot with a value.

+    ///

+    /// The given value doesn't need to satisfy any particular lifetime constraints.

+    ///

+    /// # Panics

+    ///

+    /// Calling more than a single `fill` method on this slot will panic.

+    pub fn fill_any<T>(&mut self, value: T) -> Result<(), Error>

+    where

+        T: Into<Value<'f>>,

+    {

+        self.fill(|visitor| value.into().inner.visit(visitor))

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    use super::*;

+

+    #[test]

+    fn fill_value_borrowed() {

+        struct TestFill;

+

+        impl Fill for TestFill {

+            fn fill(&self, slot: &mut Slot) -> Result<(), Error> {

+                let dbg: &dyn fmt::Debug = &1;

+

+                slot.fill_debug(&dbg)

+            }

+        }

+

+        assert_eq!("1", Value::from_fill(&TestFill).to_string());

+    }

+

+    #[test]

+    fn fill_value_owned() {

+        struct TestFill;

+

+        impl Fill for TestFill {

+            fn fill(&self, slot: &mut Slot) -> Result<(), Error> {

+                slot.fill_any("a string")

+            }

+        }

+    }

+

+    #[test]

+    #[should_panic]

+    fn fill_multiple_times_panics() {

+        struct BadFill;

+

+        impl Fill for BadFill {

+            fn fill(&self, slot: &mut Slot) -> Result<(), Error> {

+                slot.fill_any(42)?;

+                slot.fill_any(6789)?;

+

+                Ok(())

+            }

+        }

+

+        let _ = Value::from_fill(&BadFill).to_string();

+    }

+

+    #[test]

+    fn fill_cast() {

+        struct TestFill;

+

+        impl Fill for TestFill {

+            fn fill(&self, slot: &mut Slot) -> Result<(), Error> {

+                slot.fill_any("a string")

+            }

+        }

+

+        assert_eq!(

+            "a string",

+            Value::from_fill(&TestFill)

+                .to_borrowed_str()

+                .expect("invalid value")

+        );

+    }

+

+    #[test]

+    fn fill_debug() {

+        struct TestFill;

+

+        impl Fill for TestFill {

+            fn fill(&self, slot: &mut Slot) -> Result<(), Error> {

+                slot.fill_any(42u64)

+            }

+        }

+

+        assert_eq!(

+            format!("{:04?}", 42u64),

+            format!("{:04?}", Value::from_fill(&TestFill)),

+        )

+    }

+}

diff --git a/src/kv/value/impls.rs b/src/kv/value/impls.rs
index ea18146..8752dbe 100644
--- a/src/kv/value/impls.rs
+++ b/src/kv/value/impls.rs
@@ -1,269 +1,159 @@
-use std::fmt;
-
-use super::{ToValue, Value, Primitive};
-
-impl ToValue for usize {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<usize> for Value<'v> {
-    fn from(value: usize) -> Self {
-        Value::from_primitive(Primitive::Unsigned(value as u64))
-    }
-}
-
-impl ToValue for isize {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<isize> for Value<'v> {
-    fn from(value: isize) -> Self {
-        Value::from_primitive(Primitive::Signed(value as i64))
-    }
-}
-
-impl ToValue for u8 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<u8> for Value<'v> {
-    fn from(value: u8) -> Self {
-        Value::from_primitive(Primitive::Unsigned(value as u64))
-    }
-}
-
-impl ToValue for u16 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<u16> for Value<'v> {
-    fn from(value: u16) -> Self {
-        Value::from_primitive(Primitive::Unsigned(value as u64))
-    }
-}
-
-impl ToValue for u32 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<u32> for Value<'v> {
-    fn from(value: u32) -> Self {
-        Value::from_primitive(Primitive::Unsigned(value as u64))
-    }
-}
-
-impl ToValue for u64 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<u64> for Value<'v> {
-    fn from(value: u64) -> Self {
-        Value::from_primitive(Primitive::Unsigned(value))
-    }
-}
-
-impl ToValue for i8 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<i8> for Value<'v> {
-    fn from(value: i8) -> Self {
-        Value::from_primitive(Primitive::Signed(value as i64))
-    }
-}
-
-impl ToValue for i16 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<i16> for Value<'v> {
-    fn from(value: i16) -> Self {
-        Value::from_primitive(Primitive::Signed(value as i64))
-    }
-}
-
-impl ToValue for i32 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<i32> for Value<'v> {
-    fn from(value: i32) -> Self {
-        Value::from_primitive(Primitive::Signed(value as i64))
-    }
-}
-
-impl ToValue for i64 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<i64> for Value<'v> {
-    fn from(value: i64) -> Self {
-        Value::from_primitive(Primitive::Signed(value))
-    }
-}
-
-impl ToValue for f32 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<f32> for Value<'v> {
-    fn from(value: f32) -> Self {
-        Value::from_primitive(Primitive::Float(value as f64))
-    }
-}
-
-impl ToValue for f64 {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<f64> for Value<'v> {
-    fn from(value: f64) -> Self {
-        Value::from_primitive(Primitive::Float(value))
-    }
-}
-
-impl ToValue for bool {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<bool> for Value<'v> {
-    fn from(value: bool) -> Self {
-        Value::from_primitive(Primitive::Bool(value))
-    }
-}
-
-impl ToValue for char {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<char> for Value<'v> {
-    fn from(value: char) -> Self {
-        Value::from_primitive(Primitive::Char(value))
-    }
-}
-
-impl<'v> ToValue for &'v str {
-    fn to_value(&self) -> Value {
-        Value::from(*self)
-    }
-}
-
-impl<'v> From<&'v str> for Value<'v> {
-    fn from(value: &'v str) -> Self {
-        Value::from_primitive(Primitive::Str(value))
-    }
-}
-
-impl ToValue for () {
-    fn to_value(&self) -> Value {
-        Value::from_primitive(Primitive::None)
-    }
-}
-
-impl<T> ToValue for Option<T>
-where
-    T: ToValue,
-{
-    fn to_value(&self) -> Value {
-        match *self {
-            Some(ref value) => value.to_value(),
-            None => Value::from_primitive(Primitive::None),
-        }
-    }
-}
-
-impl<'v> ToValue for fmt::Arguments<'v> {
-    fn to_value(&self) -> Value {
-        Value::from_debug(self)
-    }
-}
-
-#[cfg(feature = "std")]
-mod std_support {
-    use super::*;
-
-    use std::borrow::Cow;
-
-    impl<T> ToValue for Box<T>
-    where
-        T: ToValue + ?Sized,
-    {
-        fn to_value(&self) -> Value {
-            (**self).to_value()
-        }
-    }
-
-    impl ToValue for String {
-        fn to_value(&self) -> Value {
-            Value::from_primitive(Primitive::Str(&*self))
-        }
-    }
-
-    impl<'v> ToValue for Cow<'v, str> {
-        fn to_value(&self) -> Value {
-            Value::from_primitive(Primitive::Str(&*self))
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-    use kv::value::test::Token;
-
-    #[test]
-    fn test_to_value_display() {
-        assert_eq!(42u64.to_value().to_string(), "42");
-        assert_eq!(42i64.to_value().to_string(), "42");
-        assert_eq!(42.01f64.to_value().to_string(), "42.01");
-        assert_eq!(true.to_value().to_string(), "true");
-        assert_eq!('a'.to_value().to_string(), "'a'");
-        assert_eq!(format_args!("a {}", "value").to_value().to_string(), "a value");
-        assert_eq!("a loong string".to_value().to_string(), "\"a loong string\"");
-        assert_eq!(Some(true).to_value().to_string(), "true");
-        assert_eq!(().to_value().to_string(), "None");
-        assert_eq!(Option::None::<bool>.to_value().to_string(), "None");
-    }
-
-    #[test]
-    fn test_to_value_structured() {
-        assert_eq!(42u64.to_value().to_token(), Token::U64(42));
-        assert_eq!(42i64.to_value().to_token(), Token::I64(42));
-        assert_eq!(42.01f64.to_value().to_token(), Token::F64(42.01));
-        assert_eq!(true.to_value().to_token(), Token::Bool(true));
-        assert_eq!('a'.to_value().to_token(), Token::Char('a'));
-        assert_eq!(format_args!("a {}", "value").to_value().to_token(), Token::Str("a value".into()));
-        assert_eq!("a loong string".to_value().to_token(), Token::Str("a loong string".into()));
-        assert_eq!(Some(true).to_value().to_token(), Token::Bool(true));
-        assert_eq!(().to_value().to_token(), Token::None);
-        assert_eq!(Option::None::<bool>.to_value().to_token(), Token::None);
-    }
-}
+//! Converting standard types into `Value`s.

+//!

+//! This module provides `ToValue` implementations for commonly

+//! logged types from the standard library.

+

+use std::fmt;

+

+use super::{Primitive, ToValue, Value};

+

+macro_rules! impl_into_owned {

+    ($($into_ty:ty => $convert:ident,)*) => {

+        $(

+            impl ToValue for $into_ty {

+                fn to_value(&self) -> Value {

+                    Value::from(*self)

+                }

+            }

+

+            impl<'v> From<$into_ty> for Value<'v> {

+                fn from(value: $into_ty) -> Self {

+                    Value::from_primitive(value as $convert)

+                }

+            }

+        )*

+    };

+}

+

+impl<'v> ToValue for &'v str {

+    fn to_value(&self) -> Value {

+        Value::from(*self)

+    }

+}

+

+impl<'v> From<&'v str> for Value<'v> {

+    fn from(value: &'v str) -> Self {

+        Value::from_primitive(value)

+    }

+}

+

+impl<'v> ToValue for fmt::Arguments<'v> {

+    fn to_value(&self) -> Value {

+        Value::from(*self)

+    }

+}

+

+impl<'v> From<fmt::Arguments<'v>> for Value<'v> {

+    fn from(value: fmt::Arguments<'v>) -> Self {

+        Value::from_primitive(value)

+    }

+}

+

+impl ToValue for () {

+    fn to_value(&self) -> Value {

+        Value::from_primitive(Primitive::None)

+    }

+}

+

+impl<T> ToValue for Option<T>

+where

+    T: ToValue,

+{

+    fn to_value(&self) -> Value {

+        match *self {

+            Some(ref value) => value.to_value(),

+            None => Value::from_primitive(Primitive::None),

+        }

+    }

+}

+

+impl_into_owned! [

+    usize => u64,

+    u8 => u64,

+    u16 => u64,

+    u32 => u64,

+    u64 => u64,

+

+    isize => i64,

+    i8 => i64,

+    i16 => i64,

+    i32 => i64,

+    i64 => i64,

+

+    f32 => f64,

+    f64 => f64,

+

+    char => char,

+    bool => bool,

+];

+

+#[cfg(feature = "std")]

+mod std_support {

+    use super::*;

+

+    use std::borrow::Cow;

+

+    impl<T> ToValue for Box<T>

+    where

+        T: ToValue + ?Sized,

+    {

+        fn to_value(&self) -> Value {

+            (**self).to_value()

+        }

+    }

+

+    impl ToValue for String {

+        fn to_value(&self) -> Value {

+            Value::from_primitive(Primitive::Str(&*self))

+        }

+    }

+

+    impl<'v> ToValue for Cow<'v, str> {

+        fn to_value(&self) -> Value {

+            Value::from_primitive(Primitive::Str(&*self))

+        }

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    use super::*;

+    use kv::value::test::Token;

+

+    #[test]

+    fn test_to_value_display() {

+        assert_eq!(42u64.to_value().to_string(), "42");

+        assert_eq!(42i64.to_value().to_string(), "42");

+        assert_eq!(42.01f64.to_value().to_string(), "42.01");

+        assert_eq!(true.to_value().to_string(), "true");

+        assert_eq!('a'.to_value().to_string(), "a");

+        assert_eq!(

+            format_args!("a {}", "value").to_value().to_string(),

+            "a value"

+        );

+        assert_eq!("a loong string".to_value().to_string(), "a loong string");

+        assert_eq!(Some(true).to_value().to_string(), "true");

+        assert_eq!(().to_value().to_string(), "None");

+        assert_eq!(Option::None::<bool>.to_value().to_string(), "None");

+    }

+

+    #[test]

+    fn test_to_value_structured() {

+        assert_eq!(42u64.to_value().to_token(), Token::U64(42));

+        assert_eq!(42i64.to_value().to_token(), Token::I64(42));

+        assert_eq!(42.01f64.to_value().to_token(), Token::F64(42.01));

+        assert_eq!(true.to_value().to_token(), Token::Bool(true));

+        assert_eq!('a'.to_value().to_token(), Token::Char('a'));

+        assert_eq!(

+            format_args!("a {}", "value").to_value().to_token(),

+            Token::Str("a value".into())

+        );

+        assert_eq!(

+            "a loong string".to_value().to_token(),

+            Token::Str("a loong string".into())

+        );

+        assert_eq!(Some(true).to_value().to_token(), Token::Bool(true));

+        assert_eq!(().to_value().to_token(), Token::None);

+        assert_eq!(Option::None::<bool>.to_value().to_token(), Token::None);

+    }

+}

diff --git a/src/kv/value/internal.rs b/src/kv/value/internal.rs
deleted file mode 100644
index 5f01a31..0000000
--- a/src/kv/value/internal.rs
+++ /dev/null
@@ -1,264 +0,0 @@
-use std::fmt;
-
-use super::{Fill, Slot, Error};
-use kv;
-
-// `Visitor` is an internal API for visiting the structure of a value.
-// It's not intended to be public (at this stage).
-
-/// A container for a structured value for a specific kind of visitor.
-#[derive(Clone, Copy)]
-pub(super) enum Inner<'v> {
-    /// A simple primitive value that can be copied without allocating.
-    Primitive(Primitive<'v>),
-    /// A value that can be filled.
-    Fill(&'v Fill),
-    /// A debuggable value.
-    Debug(&'v fmt::Debug),
-    /// A displayable value.
-    Display(&'v fmt::Display),
-
-    #[cfg(feature = "kv_unstable_sval")]
-    /// A structured value from `sval`.
-    Sval(&'v sval_support::Value),
-}
-
-impl<'v> Inner<'v> {
-    pub(super) fn visit(&self, visitor: &mut Visitor) -> Result<(), Error> {
-        match *self {
-            Inner::Primitive(value) => match value {
-                Primitive::Signed(value) => visitor.i64(value),
-                Primitive::Unsigned(value) => visitor.u64(value),
-                Primitive::Float(value) => visitor.f64(value),
-                Primitive::Bool(value) => visitor.bool(value),
-                Primitive::Char(value) => visitor.char(value),
-                Primitive::Str(value) => visitor.str(value),
-                Primitive::None => visitor.none(),
-            },
-            Inner::Fill(value) => value.fill(&mut Slot::new(visitor)),
-            Inner::Debug(value) => visitor.debug(value),
-            Inner::Display(value) => visitor.display(value),
-
-            #[cfg(feature = "kv_unstable_sval")]
-            Inner::Sval(value) => visitor.sval(value),
-        }
-    }
-}
-
-/// The internal serialization contract.
-pub(super) trait Visitor {
-    fn debug(&mut self, v: &fmt::Debug) -> Result<(), Error>;
-    fn display(&mut self, v: &fmt::Display) -> Result<(), Error> {
-        self.debug(&format_args!("{}",  v))
-    }
-
-    fn u64(&mut self, v: u64) -> Result<(), Error>;
-    fn i64(&mut self, v: i64) -> Result<(), Error>;
-    fn f64(&mut self, v: f64) -> Result<(), Error>;
-    fn bool(&mut self, v: bool) -> Result<(), Error>;
-    fn char(&mut self, v: char) -> Result<(), Error>;
-    fn str(&mut self, v: &str) -> Result<(), Error>;
-    fn none(&mut self) -> Result<(), Error>;
-
-    #[cfg(feature = "kv_unstable_sval")]
-    fn sval(&mut self, v: &sval_support::Value) -> Result<(), Error>;
-}
-
-#[derive(Clone, Copy)]
-pub(super) enum Primitive<'v> {
-    Signed(i64),
-    Unsigned(u64),
-    Float(f64),
-    Bool(bool),
-    Char(char),
-    Str(&'v str),
-    None,
-}
-
-mod fmt_support {
-    use super::*;
-
-    impl<'v> kv::Value<'v> {
-        /// Get a value from a debuggable type.
-        pub fn from_debug<T>(value: &'v T) -> Self
-        where
-            T: fmt::Debug,
-        {
-            kv::Value {
-                inner: Inner::Debug(value),
-            }
-        }
-
-        /// Get a value from a displayable type.
-        pub fn from_display<T>(value: &'v T) -> Self
-        where
-            T: fmt::Display,
-        {
-            kv::Value {
-                inner: Inner::Display(value),
-            }
-        }
-    }
-
-    impl<'v> fmt::Debug for kv::Value<'v> {
-        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-            self.visit(&mut FmtVisitor(f))?;
-
-            Ok(())
-        }
-    }
-
-    impl<'v> fmt::Display for kv::Value<'v> {
-        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-            self.visit(&mut FmtVisitor(f))?;
-
-            Ok(())
-        }
-    }
-    
-    struct FmtVisitor<'a, 'b: 'a>(&'a mut fmt::Formatter<'b>);
-
-    impl<'a, 'b: 'a> Visitor for FmtVisitor<'a, 'b> {
-        fn debug(&mut self, v: &fmt::Debug) -> Result<(), Error> {
-            v.fmt(self.0)?;
-
-            Ok(())
-        }
-
-        fn u64(&mut self, v: u64) -> Result<(), Error> {
-            self.debug(&format_args!("{:?}", v))
-        }
-
-        fn i64(&mut self, v: i64) -> Result<(), Error> {
-            self.debug(&format_args!("{:?}", v))
-        }
-
-        fn f64(&mut self, v: f64) -> Result<(), Error> {
-            self.debug(&format_args!("{:?}", v))
-        }
-
-        fn bool(&mut self, v: bool) -> Result<(), Error> {
-            self.debug(&format_args!("{:?}", v))
-        }
-
-        fn char(&mut self, v: char) -> Result<(), Error> {
-            self.debug(&format_args!("{:?}", v))
-        }
-
-        fn str(&mut self, v: &str) -> Result<(), Error> {
-            self.debug(&format_args!("{:?}", v))
-        }
-
-        fn none(&mut self) -> Result<(), Error> {
-            self.debug(&format_args!("None"))
-        }
-
-        #[cfg(feature = "kv_unstable_sval")]
-        fn sval(&mut self, v: &sval_support::Value) -> Result<(), Error> {
-            sval_support::fmt(self.0, v)
-        }
-    }
-}
-
-#[cfg(feature = "kv_unstable_sval")]
-pub(super) mod sval_support {
-    use super::*;
-
-    extern crate sval;
-
-    impl<'v> kv::Value<'v> {
-        /// Get a value from a structured type.
-        pub fn from_sval<T>(value: &'v T) -> Self
-        where
-            T: sval::Value,
-        {
-            kv::Value {
-                inner: Inner::Sval(value),
-            }
-        }
-    }
-
-    impl<'v> sval::Value for kv::Value<'v> {
-        fn stream(&self, s: &mut sval::value::Stream) -> sval::value::Result {
-            self.visit(&mut SvalVisitor(s)).map_err(Error::into_sval)?;
-
-            Ok(())
-        }
-    }
-
-    pub(in kv::value) use self::sval::Value;
-
-    pub(super) fn fmt(f: &mut fmt::Formatter, v: &sval::Value) -> Result<(), Error> {
-        sval::fmt::debug(f, v)?;
-        Ok(())
-    }
-
-    impl Error {
-        fn from_sval(_: sval::value::Error) -> Self {
-            Error::msg("`sval` serialization failed")
-        }
-        
-        fn into_sval(self) -> sval::value::Error {
-            sval::value::Error::msg("`sval` serialization failed")
-        }
-    }
-
-    struct SvalVisitor<'a, 'b: 'a>(&'a mut sval::value::Stream<'b>);
-
-    impl<'a, 'b: 'a> Visitor for SvalVisitor<'a, 'b> {
-        fn debug(&mut self, v: &fmt::Debug) -> Result<(), Error> {
-            self.0.fmt(format_args!("{:?}", v)).map_err(Error::from_sval)
-        }
-
-        fn u64(&mut self, v: u64) -> Result<(), Error> {
-            self.0.u64(v).map_err(Error::from_sval)
-        }
-
-        fn i64(&mut self, v: i64) -> Result<(), Error> {
-            self.0.i64(v).map_err(Error::from_sval)
-        }
-
-        fn f64(&mut self, v: f64) -> Result<(), Error> {
-            self.0.f64(v).map_err(Error::from_sval)
-        }
-
-        fn bool(&mut self, v: bool) -> Result<(), Error> {
-            self.0.bool(v).map_err(Error::from_sval)
-        }
-
-        fn char(&mut self, v: char) -> Result<(), Error> {
-            self.0.char(v).map_err(Error::from_sval)
-        }
-
-        fn str(&mut self, v: &str) -> Result<(), Error> {
-            self.0.str(v).map_err(Error::from_sval)
-        }
-
-        fn none(&mut self) -> Result<(), Error> {
-            self.0.none().map_err(Error::from_sval)
-        }
-
-        fn sval(&mut self, v: &sval::Value) -> Result<(), Error> {
-            self.0.any(v).map_err(Error::from_sval)
-        }
-    }
-
-    #[cfg(test)]
-    mod tests {
-        use super::*;
-        use kv::value::test::Token;
-
-        #[test]
-        fn test_from_sval() {
-            assert_eq!(kv::Value::from_sval(&42u64).to_token(), Token::Sval);
-        }
-
-        #[test]
-        fn test_sval_structured() {
-            let value = kv::Value::from(42u64);
-            let expected = vec![sval::test::Token::Unsigned(42)];
-
-            assert_eq!(sval::test::tokens(value), expected);
-        }
-    }
-}
diff --git a/src/kv/value/internal/cast.rs b/src/kv/value/internal/cast.rs
new file mode 100644
index 0000000..aaa4b07
--- /dev/null
+++ b/src/kv/value/internal/cast.rs
@@ -0,0 +1,475 @@
+//! Coerce a `Value` into some concrete types.

+//!

+//! These operations are cheap when the captured value is a simple primitive,

+//! but may end up executing arbitrary caller code if the value is complex.

+//! They will also attempt to downcast erased types into a primitive where possible.

+

+use std::any::TypeId;

+use std::fmt;

+

+use super::{Erased, Inner, Primitive, Visitor};

+use crate::kv::value::{Error, Value};

+

+impl<'v> Value<'v> {

+    /// Try get a `usize` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_usize(&self) -> Option<usize> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_u64()

+            .map(|v| v as usize)

+    }

+

+    /// Try get a `u8` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_u8(&self) -> Option<u8> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_u64()

+            .map(|v| v as u8)

+    }

+

+    /// Try get a `u16` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_u16(&self) -> Option<u16> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_u64()

+            .map(|v| v as u16)

+    }

+

+    /// Try get a `u32` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_u32(&self) -> Option<u32> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_u64()

+            .map(|v| v as u32)

+    }

+

+    /// Try get a `u64` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_u64(&self) -> Option<u64> {

+        self.inner.cast().into_primitive().into_u64()

+    }

+

+    /// Try get a `isize` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_isize(&self) -> Option<isize> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_i64()

+            .map(|v| v as isize)

+    }

+

+    /// Try get a `i8` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_i8(&self) -> Option<i8> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_i64()

+            .map(|v| v as i8)

+    }

+

+    /// Try get a `i16` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_i16(&self) -> Option<i16> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_i64()

+            .map(|v| v as i16)

+    }

+

+    /// Try get a `i32` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_i32(&self) -> Option<i32> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_i64()

+            .map(|v| v as i32)

+    }

+

+    /// Try get a `i64` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_i64(&self) -> Option<i64> {

+        self.inner.cast().into_primitive().into_i64()

+    }

+

+    /// Try get a `f32` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_f32(&self) -> Option<f32> {

+        self.inner

+            .cast()

+            .into_primitive()

+            .into_f64()

+            .map(|v| v as f32)

+    }

+

+    /// Try get a `f64` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_f64(&self) -> Option<f64> {

+        self.inner.cast().into_primitive().into_f64()

+    }

+

+    /// Try get a `bool` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_bool(&self) -> Option<bool> {

+        self.inner.cast().into_primitive().into_bool()

+    }

+

+    /// Try get a `char` from this value.

+    ///

+    /// This method is cheap for primitive types, but may call arbitrary

+    /// serialization implementations for complex ones.

+    pub fn to_char(&self) -> Option<char> {

+        self.inner.cast().into_primitive().into_char()

+    }

+

+    /// Try get a `str` from this value.

+    ///

+    /// This method is cheap for primitive types. It won't allocate an owned

+    /// `String` if the value is a complex type.

+    pub fn to_borrowed_str(&self) -> Option<&str> {

+        self.inner.cast().into_primitive().into_borrowed_str()

+    }

+}

+

+impl<'v> Inner<'v> {

+    /// Cast the inner value to another type.

+    fn cast(self) -> Cast<'v> {

+        struct CastVisitor<'v>(Cast<'v>);

+

+        impl<'v> Visitor<'v> for CastVisitor<'v> {

+            fn debug(&mut self, _: &dyn fmt::Debug) -> Result<(), Error> {

+                Ok(())

+            }

+

+            fn u64(&mut self, v: u64) -> Result<(), Error> {

+                self.0 = Cast::Primitive(Primitive::Unsigned(v));

+                Ok(())

+            }

+

+            fn i64(&mut self, v: i64) -> Result<(), Error> {

+                self.0 = Cast::Primitive(Primitive::Signed(v));

+                Ok(())

+            }

+

+            fn f64(&mut self, v: f64) -> Result<(), Error> {

+                self.0 = Cast::Primitive(Primitive::Float(v));

+                Ok(())

+            }

+

+            fn bool(&mut self, v: bool) -> Result<(), Error> {

+                self.0 = Cast::Primitive(Primitive::Bool(v));

+                Ok(())

+            }

+

+            fn char(&mut self, v: char) -> Result<(), Error> {

+                self.0 = Cast::Primitive(Primitive::Char(v));

+                Ok(())

+            }

+

+            fn borrowed_str(&mut self, v: &'v str) -> Result<(), Error> {

+                self.0 = Cast::Primitive(Primitive::Str(v));

+                Ok(())

+            }

+

+            #[cfg(not(feature = "std"))]

+            fn str(&mut self, _: &str) -> Result<(), Error> {

+                Ok(())

+            }

+

+            #[cfg(feature = "std")]

+            fn str(&mut self, v: &str) -> Result<(), Error> {

+                self.0 = Cast::String(v.into());

+                Ok(())

+            }

+

+            fn none(&mut self) -> Result<(), Error> {

+                self.0 = Cast::Primitive(Primitive::None);

+                Ok(())

+            }

+

+            #[cfg(feature = "kv_unstable_sval")]

+            fn sval(&mut self, v: &dyn super::sval::Value) -> Result<(), Error> {

+                self.0 = super::sval::cast(v);

+                Ok(())

+            }

+        }

+

+        // Try downcast an erased value first

+        // It also lets us avoid the Visitor infrastructure for simple primitives

+        let primitive = match self {

+            Inner::Primitive(value) => Some(value),

+            Inner::Fill(value) => value.downcast_primitive(),

+            Inner::Debug(value) => value.downcast_primitive(),

+            Inner::Display(value) => value.downcast_primitive(),

+

+            #[cfg(feature = "sval")]

+            Inner::Sval(value) => value.downcast_primitive(),

+        };

+

+        primitive.map(Cast::Primitive).unwrap_or_else(|| {

+            // If the erased value isn't a primitive then we visit it

+            let mut cast = CastVisitor(Cast::Primitive(Primitive::None));

+            let _ = self.visit(&mut cast);

+            cast.0

+        })

+    }

+}

+

+pub(super) enum Cast<'v> {

+    Primitive(Primitive<'v>),

+    #[cfg(feature = "std")]

+    String(String),

+}

+

+impl<'v> Cast<'v> {

+    fn into_primitive(self) -> Primitive<'v> {

+        match self {

+            Cast::Primitive(value) => value,

+            #[cfg(feature = "std")]

+            _ => Primitive::None,

+        }

+    }

+}

+

+impl<'v> Primitive<'v> {

+    fn into_borrowed_str(self) -> Option<&'v str> {

+        if let Primitive::Str(value) = self {

+            Some(value)

+        } else {

+            None

+        }

+    }

+

+    fn into_u64(self) -> Option<u64> {

+        match self {

+            Primitive::Unsigned(value) => Some(value),

+            Primitive::Signed(value) => Some(value as u64),

+            Primitive::Float(value) => Some(value as u64),

+            _ => None,

+        }

+    }

+

+    fn into_i64(self) -> Option<i64> {

+        match self {

+            Primitive::Signed(value) => Some(value),

+            Primitive::Unsigned(value) => Some(value as i64),

+            Primitive::Float(value) => Some(value as i64),

+            _ => None,

+        }

+    }

+

+    fn into_f64(self) -> Option<f64> {

+        match self {

+            Primitive::Float(value) => Some(value),

+            Primitive::Unsigned(value) => Some(value as f64),

+            Primitive::Signed(value) => Some(value as f64),

+            _ => None,

+        }

+    }

+

+    fn into_char(self) -> Option<char> {

+        if let Primitive::Char(value) = self {

+            Some(value)

+        } else {

+            None

+        }

+    }

+

+    fn into_bool(self) -> Option<bool> {

+        if let Primitive::Bool(value) = self {

+            Some(value)

+        } else {

+            None

+        }

+    }

+}

+

+impl<'v, T: ?Sized + 'static> Erased<'v, T> {

+    // NOTE: This function is a perfect candidate for memoization

+    // The outcome could be stored in a `Cell<Primitive>`

+    fn downcast_primitive(self) -> Option<Primitive<'v>> {

+        macro_rules! type_ids {

+            ($($value:ident : $ty:ty => $cast:expr,)*) => {{

+                struct TypeIds;

+

+                impl TypeIds {

+                    fn downcast_primitive<'v, T: ?Sized>(&self, value: Erased<'v, T>) -> Option<Primitive<'v>> {

+                        $(

+                            if TypeId::of::<$ty>() == value.type_id {

+                                let $value = unsafe { value.downcast_unchecked::<$ty>() };

+                                return Some(Primitive::from($cast));

+                            }

+                        )*

+

+                        None

+                    }

+                }

+

+                TypeIds

+            }};

+        }

+

+        let type_ids = type_ids![

+            value: usize => *value as u64,

+            value: u8 => *value as u64,

+            value: u16 => *value as u64,

+            value: u32 => *value as u64,

+            value: u64 => *value,

+

+            value: isize => *value as i64,

+            value: i8 => *value as i64,

+            value: i16 => *value as i64,

+            value: i32 => *value as i64,

+            value: i64 => *value,

+

+            value: f32 => *value as f64,

+            value: f64 => *value,

+

+            value: char => *value,

+            value: bool => *value,

+

+            value: &str => *value,

+        ];

+

+        type_ids.downcast_primitive(self)

+    }

+}

+

+#[cfg(feature = "std")]

+mod std_support {

+    use super::*;

+

+    use std::borrow::Cow;

+

+    impl<'v> Value<'v> {

+        /// Try get a `usize` from this value.

+        ///

+        /// This method is cheap for primitive types, but may call arbitrary

+        /// serialization implementations for complex ones. If the serialization

+        /// implementation produces a short lived string it will be allocated.

+        pub fn to_str(&self) -> Option<Cow<str>> {

+            self.inner.cast().into_str()

+        }

+    }

+

+    impl<'v> Cast<'v> {

+        pub(super) fn into_str(self) -> Option<Cow<'v, str>> {

+            match self {

+                Cast::Primitive(Primitive::Str(value)) => Some(value.into()),

+                Cast::String(value) => Some(value.into()),

+                _ => None,

+            }

+        }

+    }

+

+    #[cfg(test)]

+    mod tests {

+        use crate::kv::ToValue;

+

+        #[test]

+        fn primitive_cast() {

+            assert_eq!(

+                "a string",

+                "a string"

+                    .to_owned()

+                    .to_value()

+                    .to_borrowed_str()

+                    .expect("invalid value")

+            );

+            assert_eq!(

+                "a string",

+                &*"a string".to_value().to_str().expect("invalid value")

+            );

+            assert_eq!(

+                "a string",

+                &*"a string"

+                    .to_owned()

+                    .to_value()

+                    .to_str()

+                    .expect("invalid value")

+            );

+        }

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    use crate::kv::ToValue;

+

+    #[test]

+    fn primitive_cast() {

+        assert_eq!(

+            "a string",

+            "a string"

+                .to_value()

+                .to_borrowed_str()

+                .expect("invalid value")

+        );

+        assert_eq!(

+            "a string",

+            Some("a string")

+                .to_value()

+                .to_borrowed_str()

+                .expect("invalid value")

+        );

+

+        assert_eq!(1u8, 1u64.to_value().to_u8().expect("invalid value"));

+        assert_eq!(1u16, 1u64.to_value().to_u16().expect("invalid value"));

+        assert_eq!(1u32, 1u64.to_value().to_u32().expect("invalid value"));

+        assert_eq!(1u64, 1u64.to_value().to_u64().expect("invalid value"));

+        assert_eq!(1usize, 1u64.to_value().to_usize().expect("invalid value"));

+

+        assert_eq!(-1i8, -1i64.to_value().to_i8().expect("invalid value"));

+        assert_eq!(-1i16, -1i64.to_value().to_i16().expect("invalid value"));

+        assert_eq!(-1i32, -1i64.to_value().to_i32().expect("invalid value"));

+        assert_eq!(-1i64, -1i64.to_value().to_i64().expect("invalid value"));

+        assert_eq!(-1isize, -1i64.to_value().to_isize().expect("invalid value"));

+

+        assert!(1f32.to_value().to_f32().is_some(), "invalid value");

+        assert!(1f64.to_value().to_f64().is_some(), "invalid value");

+

+        assert_eq!(1u32, 1i64.to_value().to_u32().expect("invalid value"));

+        assert_eq!(1i32, 1u64.to_value().to_i32().expect("invalid value"));

+        assert!(1f32.to_value().to_i32().is_some(), "invalid value");

+

+        assert_eq!('a', 'a'.to_value().to_char().expect("invalid value"));

+        assert_eq!(true, true.to_value().to_bool().expect("invalid value"));

+    }

+}

diff --git a/src/kv/value/internal/fmt.rs b/src/kv/value/internal/fmt.rs
new file mode 100644
index 0000000..66817d4
--- /dev/null
+++ b/src/kv/value/internal/fmt.rs
@@ -0,0 +1,249 @@
+//! Integration between `Value` and `std::fmt`.

+//!

+//! This module allows any `Value` to implement the `fmt::Debug` and `fmt::Display` traits,

+//! and for any `fmt::Debug` or `fmt::Display` to be captured as a `Value`.

+

+use std::fmt;

+

+use super::{Erased, Inner, Visitor};

+use crate::kv;

+use crate::kv::value::{Error, Slot};

+

+impl<'v> kv::Value<'v> {

+    /// Get a value from a debuggable type.

+    pub fn from_debug<T>(value: &'v T) -> Self

+    where

+        T: fmt::Debug + 'static,

+    {

+        kv::Value {

+            inner: Inner::Debug(unsafe { Erased::new_unchecked::<T>(value) }),

+        }

+    }

+

+    /// Get a value from a displayable type.

+    pub fn from_display<T>(value: &'v T) -> Self

+    where

+        T: fmt::Display + 'static,

+    {

+        kv::Value {

+            inner: Inner::Display(unsafe { Erased::new_unchecked::<T>(value) }),

+        }

+    }

+}

+

+impl<'s, 'f> Slot<'s, 'f> {

+    /// Fill the slot with a debuggable value.

+    ///

+    /// The given value doesn't need to satisfy any particular lifetime constraints.

+    ///

+    /// # Panics

+    ///

+    /// Calling more than a single `fill` method on this slot will panic.

+    pub fn fill_debug<T>(&mut self, value: T) -> Result<(), Error>

+    where

+        T: fmt::Debug,

+    {

+        self.fill(|visitor| visitor.debug(&value))

+    }

+

+    /// Fill the slot with a displayable value.

+    ///

+    /// The given value doesn't need to satisfy any particular lifetime constraints.

+    ///

+    /// # Panics

+    ///

+    /// Calling more than a single `fill` method on this slot will panic.

+    pub fn fill_display<T>(&mut self, value: T) -> Result<(), Error>

+    where

+        T: fmt::Display,

+    {

+        self.fill(|visitor| visitor.display(&value))

+    }

+}

+

+pub(in kv::value) use self::fmt::{Arguments, Debug, Display};

+

+impl<'v> fmt::Debug for kv::Value<'v> {

+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

+        struct DebugVisitor<'a, 'b: 'a>(&'a mut fmt::Formatter<'b>);

+

+        impl<'a, 'b: 'a, 'v> Visitor<'v> for DebugVisitor<'a, 'b> {

+            fn debug(&mut self, v: &dyn fmt::Debug) -> Result<(), Error> {

+                fmt::Debug::fmt(v, self.0)?;

+

+                Ok(())

+            }

+

+            fn display(&mut self, v: &dyn fmt::Display) -> Result<(), Error> {

+                fmt::Display::fmt(v, self.0)?;

+

+                Ok(())

+            }

+

+            fn u64(&mut self, v: u64) -> Result<(), Error> {

+                fmt::Debug::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn i64(&mut self, v: i64) -> Result<(), Error> {

+                fmt::Debug::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn f64(&mut self, v: f64) -> Result<(), Error> {

+                fmt::Debug::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn bool(&mut self, v: bool) -> Result<(), Error> {

+                fmt::Debug::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn char(&mut self, v: char) -> Result<(), Error> {

+                fmt::Debug::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn str(&mut self, v: &str) -> Result<(), Error> {

+                fmt::Debug::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn none(&mut self) -> Result<(), Error> {

+                self.debug(&format_args!("None"))

+            }

+

+            #[cfg(feature = "kv_unstable_sval")]

+            fn sval(&mut self, v: &dyn super::sval::Value) -> Result<(), Error> {

+                super::sval::fmt(self.0, v)

+            }

+        }

+

+        self.visit(&mut DebugVisitor(f)).map_err(|_| fmt::Error)?;

+

+        Ok(())

+    }

+}

+

+impl<'v> fmt::Display for kv::Value<'v> {

+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

+        struct DisplayVisitor<'a, 'b: 'a>(&'a mut fmt::Formatter<'b>);

+

+        impl<'a, 'b: 'a, 'v> Visitor<'v> for DisplayVisitor<'a, 'b> {

+            fn debug(&mut self, v: &dyn fmt::Debug) -> Result<(), Error> {

+                fmt::Debug::fmt(v, self.0)?;

+

+                Ok(())

+            }

+

+            fn display(&mut self, v: &dyn fmt::Display) -> Result<(), Error> {

+                fmt::Display::fmt(v, self.0)?;

+

+                Ok(())

+            }

+

+            fn u64(&mut self, v: u64) -> Result<(), Error> {

+                fmt::Display::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn i64(&mut self, v: i64) -> Result<(), Error> {

+                fmt::Display::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn f64(&mut self, v: f64) -> Result<(), Error> {

+                fmt::Display::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn bool(&mut self, v: bool) -> Result<(), Error> {

+                fmt::Display::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn char(&mut self, v: char) -> Result<(), Error> {

+                fmt::Display::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn str(&mut self, v: &str) -> Result<(), Error> {

+                fmt::Display::fmt(&v, self.0)?;

+

+                Ok(())

+            }

+

+            fn none(&mut self) -> Result<(), Error> {

+                self.debug(&format_args!("None"))

+            }

+

+            #[cfg(feature = "kv_unstable_sval")]

+            fn sval(&mut self, v: &dyn super::sval::Value) -> Result<(), Error> {

+                super::sval::fmt(self.0, v)

+            }

+        }

+

+        self.visit(&mut DisplayVisitor(f)).map_err(|_| fmt::Error)?;

+

+        Ok(())

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    use super::*;

+

+    use crate::kv::value::ToValue;

+

+    #[test]

+    fn fmt_cast() {

+        assert_eq!(

+            42u32,

+            kv::Value::from_debug(&42u64)

+                .to_u32()

+                .expect("invalid value")

+        );

+

+        assert_eq!(

+            "a string",

+            kv::Value::from_display(&"a string")

+                .to_borrowed_str()

+                .expect("invalid value")

+        );

+    }

+

+    #[test]

+    fn fmt_debug() {

+        assert_eq!(

+            format!("{:?}", "a string"),

+            format!("{:?}", "a string".to_value()),

+        );

+

+        assert_eq!(

+            format!("{:04?}", 42u64),

+            format!("{:04?}", 42u64.to_value()),

+        );

+    }

+

+    #[test]

+    fn fmt_display() {

+        assert_eq!(

+            format!("{}", "a string"),

+            format!("{}", "a string".to_value()),

+        );

+

+        assert_eq!(format!("{:04}", 42u64), format!("{:04}", 42u64.to_value()),);

+    }

+}

diff --git a/src/kv/value/internal/mod.rs b/src/kv/value/internal/mod.rs
new file mode 100644
index 0000000..01b72a7
--- /dev/null
+++ b/src/kv/value/internal/mod.rs
@@ -0,0 +1,181 @@
+//! The internal `Value` serialization API.

+//!

+//! This implementation isn't intended to be public. It may need to change

+//! for optimizations or to support new external serialization frameworks.

+

+use std::any::TypeId;

+

+use super::{Error, Fill, Slot};

+

+pub(super) mod cast;

+pub(super) mod fmt;

+#[cfg(feature = "kv_unstable_sval")]

+pub(super) mod sval;

+

+/// A container for a structured value for a specific kind of visitor.

+#[derive(Clone, Copy)]

+pub(super) enum Inner<'v> {

+    /// A simple primitive value that can be copied without allocating.

+    Primitive(Primitive<'v>),

+    /// A value that can be filled.

+    Fill(Erased<'v, dyn Fill + 'static>),

+    /// A debuggable value.

+    Debug(Erased<'v, dyn fmt::Debug + 'static>),

+    /// A displayable value.

+    Display(Erased<'v, dyn fmt::Display + 'static>),

+

+    #[cfg(feature = "kv_unstable_sval")]

+    /// A structured value from `sval`.

+    Sval(Erased<'v, dyn sval::Value + 'static>),

+}

+

+impl<'v> Inner<'v> {

+    pub(super) fn visit(self, visitor: &mut dyn Visitor<'v>) -> Result<(), Error> {

+        match self {

+            Inner::Primitive(value) => value.visit(visitor),

+            Inner::Fill(value) => value.get().fill(&mut Slot::new(visitor)),

+            Inner::Debug(value) => visitor.debug(value.get()),

+            Inner::Display(value) => visitor.display(value.get()),

+

+            #[cfg(feature = "kv_unstable_sval")]

+            Inner::Sval(value) => visitor.sval(value.get()),

+        }

+    }

+}

+

+/// The internal serialization contract.

+pub(super) trait Visitor<'v> {

+    fn debug(&mut self, v: &dyn fmt::Debug) -> Result<(), Error>;

+    fn display(&mut self, v: &dyn fmt::Display) -> Result<(), Error> {

+        self.debug(&format_args!("{}", v))

+    }

+

+    fn u64(&mut self, v: u64) -> Result<(), Error>;

+    fn i64(&mut self, v: i64) -> Result<(), Error>;

+    fn f64(&mut self, v: f64) -> Result<(), Error>;

+    fn bool(&mut self, v: bool) -> Result<(), Error>;

+    fn char(&mut self, v: char) -> Result<(), Error>;

+

+    fn str(&mut self, v: &str) -> Result<(), Error>;

+    fn borrowed_str(&mut self, v: &'v str) -> Result<(), Error> {

+        self.str(v)

+    }

+

+    fn none(&mut self) -> Result<(), Error>;

+

+    #[cfg(feature = "kv_unstable_sval")]

+    fn sval(&mut self, v: &dyn sval::Value) -> Result<(), Error>;

+}

+

+/// A captured primitive value.

+///

+/// These values are common and cheap to copy around.

+#[derive(Clone, Copy)]

+pub(super) enum Primitive<'v> {

+    Signed(i64),

+    Unsigned(u64),

+    Float(f64),

+    Bool(bool),

+    Char(char),

+    Str(&'v str),

+    Fmt(fmt::Arguments<'v>),

+    None,

+}

+

+impl<'v> Primitive<'v> {

+    fn visit(self, visitor: &mut dyn Visitor<'v>) -> Result<(), Error> {

+        match self {

+            Primitive::Signed(value) => visitor.i64(value),

+            Primitive::Unsigned(value) => visitor.u64(value),

+            Primitive::Float(value) => visitor.f64(value),

+            Primitive::Bool(value) => visitor.bool(value),

+            Primitive::Char(value) => visitor.char(value),

+            Primitive::Str(value) => visitor.borrowed_str(value),

+            Primitive::Fmt(value) => visitor.debug(&value),

+            Primitive::None => visitor.none(),

+        }

+    }

+}

+

+impl<'v> From<u64> for Primitive<'v> {

+    fn from(v: u64) -> Self {

+        Primitive::Unsigned(v)

+    }

+}

+

+impl<'v> From<i64> for Primitive<'v> {

+    fn from(v: i64) -> Self {

+        Primitive::Signed(v)

+    }

+}

+

+impl<'v> From<f64> for Primitive<'v> {

+    fn from(v: f64) -> Self {

+        Primitive::Float(v)

+    }

+}

+

+impl<'v> From<bool> for Primitive<'v> {

+    fn from(v: bool) -> Self {

+        Primitive::Bool(v)

+    }

+}

+

+impl<'v> From<char> for Primitive<'v> {

+    fn from(v: char) -> Self {

+        Primitive::Char(v)

+    }

+}

+

+impl<'v> From<&'v str> for Primitive<'v> {

+    fn from(v: &'v str) -> Self {

+        Primitive::Str(v)

+    }

+}

+

+impl<'v> From<fmt::Arguments<'v>> for Primitive<'v> {

+    fn from(v: fmt::Arguments<'v>) -> Self {

+        Primitive::Fmt(v)

+    }

+}

+

+/// A downcastable dynamic type.

+pub(super) struct Erased<'v, T: ?Sized> {

+    type_id: TypeId,

+    inner: &'v T,

+}

+

+impl<'v, T: ?Sized> Clone for Erased<'v, T> {

+    fn clone(&self) -> Self {

+        Erased {

+            type_id: self.type_id,

+            inner: self.inner,

+        }

+    }

+}

+

+impl<'v, T: ?Sized> Copy for Erased<'v, T> {}

+

+impl<'v, T: ?Sized> Erased<'v, T> {

+    // SAFETY: `U: Unsize<T>` and the underlying value `T` must not change

+    // We could add a safe variant of this method with the `Unsize` trait

+    pub(super) unsafe fn new_unchecked<U>(inner: &'v T) -> Self

+    where

+        U: 'static,

+        T: 'static,

+    {

+        Erased {

+            type_id: TypeId::of::<U>(),

+            inner,

+        }

+    }

+

+    pub(super) fn get(self) -> &'v T {

+        self.inner

+    }

+

+    // SAFETY: The underlying type of `T` is `U`

+    pub(super) unsafe fn downcast_unchecked<U>(self) -> &'v U {

+        &*(self.inner as *const T as *const U)

+    }

+}

diff --git a/src/kv/value/internal/sval.rs b/src/kv/value/internal/sval.rs
new file mode 100644
index 0000000..618a036
--- /dev/null
+++ b/src/kv/value/internal/sval.rs
@@ -0,0 +1,210 @@
+//! Integration between `Value` and `sval`.

+//!

+//! This module allows any `Value` to implement the `sval::Value` trait,

+//! and for any `sval::Value` to be captured as a `Value`.

+

+extern crate sval;

+

+use std::fmt;

+

+use super::cast::Cast;

+use super::{Erased, Inner, Primitive, Visitor};

+use crate::kv;

+use crate::kv::value::{Error, Slot};

+

+impl<'v> kv::Value<'v> {

+    /// Get a value from a structured type.

+    pub fn from_sval<T>(value: &'v T) -> Self

+    where

+        T: sval::Value + 'static,

+    {

+        kv::Value {

+            inner: Inner::Sval(unsafe { Erased::new_unchecked::<T>(value) }),

+        }

+    }

+}

+

+impl<'s, 'f> Slot<'s, 'f> {

+    /// Fill the slot with a structured value.

+    ///

+    /// The given value doesn't need to satisfy any particular lifetime constraints.

+    ///

+    /// # Panics

+    ///

+    /// Calling more than a single `fill` method on this slot will panic.

+    pub fn fill_sval<T>(&mut self, value: T) -> Result<(), Error>

+    where

+        T: sval::Value,

+    {

+        self.fill(|visitor| visitor.sval(&value))

+    }

+}

+

+impl<'v> sval::Value for kv::Value<'v> {

+    fn stream(&self, s: &mut sval::value::Stream) -> sval::value::Result {

+        struct SvalVisitor<'a, 'b: 'a>(&'a mut sval::value::Stream<'b>);

+

+        impl<'a, 'b: 'a, 'v> Visitor<'v> for SvalVisitor<'a, 'b> {

+            fn debug(&mut self, v: &dyn fmt::Debug) -> Result<(), Error> {

+                self.0

+                    .fmt(format_args!("{:?}", v))

+                    .map_err(Error::from_sval)

+            }

+

+            fn u64(&mut self, v: u64) -> Result<(), Error> {

+                self.0.u64(v).map_err(Error::from_sval)

+            }

+

+            fn i64(&mut self, v: i64) -> Result<(), Error> {

+                self.0.i64(v).map_err(Error::from_sval)

+            }

+

+            fn f64(&mut self, v: f64) -> Result<(), Error> {

+                self.0.f64(v).map_err(Error::from_sval)

+            }

+

+            fn bool(&mut self, v: bool) -> Result<(), Error> {

+                self.0.bool(v).map_err(Error::from_sval)

+            }

+

+            fn char(&mut self, v: char) -> Result<(), Error> {

+                self.0.char(v).map_err(Error::from_sval)

+            }

+

+            fn str(&mut self, v: &str) -> Result<(), Error> {

+                self.0.str(v).map_err(Error::from_sval)

+            }

+

+            fn none(&mut self) -> Result<(), Error> {

+                self.0.none().map_err(Error::from_sval)

+            }

+

+            fn sval(&mut self, v: &dyn sval::Value) -> Result<(), Error> {

+                self.0.any(v).map_err(Error::from_sval)

+            }

+        }

+

+        self.visit(&mut SvalVisitor(s)).map_err(Error::into_sval)?;

+

+        Ok(())

+    }

+}

+

+pub(in kv::value) use self::sval::Value;

+

+pub(super) fn fmt(f: &mut fmt::Formatter, v: &dyn sval::Value) -> Result<(), Error> {

+    sval::fmt::debug(f, v)?;

+    Ok(())

+}

+

+pub(super) fn cast<'v>(v: &dyn sval::Value) -> Cast<'v> {

+    struct CastStream<'v>(Cast<'v>);

+

+    impl<'v> sval::Stream for CastStream<'v> {

+        fn u64(&mut self, v: u64) -> sval::stream::Result {

+            self.0 = Cast::Primitive(Primitive::Unsigned(v));

+            Ok(())

+        }

+

+        fn i64(&mut self, v: i64) -> sval::stream::Result {

+            self.0 = Cast::Primitive(Primitive::Signed(v));

+            Ok(())

+        }

+

+        fn f64(&mut self, v: f64) -> sval::stream::Result {

+            self.0 = Cast::Primitive(Primitive::Float(v));

+            Ok(())

+        }

+

+        fn char(&mut self, v: char) -> sval::stream::Result {

+            self.0 = Cast::Primitive(Primitive::Char(v));

+            Ok(())

+        }

+

+        fn bool(&mut self, v: bool) -> sval::stream::Result {

+            self.0 = Cast::Primitive(Primitive::Bool(v));

+            Ok(())

+        }

+

+        #[cfg(feature = "std")]

+        fn str(&mut self, s: &str) -> sval::stream::Result {

+            self.0 = Cast::String(s.into());

+            Ok(())

+        }

+    }

+

+    let mut cast = CastStream(Cast::Primitive(Primitive::None));

+    let _ = sval::stream(&mut cast, v);

+

+    cast.0

+}

+

+impl Error {

+    fn from_sval(_: sval::value::Error) -> Self {

+        Error::msg("`sval` serialization failed")

+    }

+

+    fn into_sval(self) -> sval::value::Error {

+        sval::value::Error::msg("`sval` serialization failed")

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    use super::*;

+    use kv::value::test::Token;

+

+    #[test]

+    fn test_from_sval() {

+        assert_eq!(kv::Value::from_sval(&42u64).to_token(), Token::Sval);

+    }

+

+    #[test]

+    fn test_sval_structured() {

+        let value = kv::Value::from(42u64);

+        let expected = vec![sval::test::Token::Unsigned(42)];

+

+        assert_eq!(sval::test::tokens(value), expected);

+    }

+

+    #[test]

+    fn sval_cast() {

+        assert_eq!(

+            42u32,

+            kv::Value::from_sval(&42u64)

+                .to_u32()

+                .expect("invalid value")

+        );

+

+        assert_eq!(

+            "a string",

+            kv::Value::from_sval(&"a string")

+                .to_borrowed_str()

+                .expect("invalid value")

+        );

+

+        #[cfg(feature = "std")]

+        assert_eq!(

+            "a string",

+            kv::Value::from_sval(&"a string")

+                .to_str()

+                .expect("invalid value")

+        );

+    }

+

+    #[test]

+    fn sval_debug() {

+        struct TestSval;

+

+        impl sval::Value for TestSval {

+            fn stream(&self, stream: &mut sval::value::Stream) -> sval::value::Result {

+                stream.u64(42)

+            }

+        }

+

+        assert_eq!(

+            format!("{:04?}", 42u64),

+            format!("{:04?}", kv::Value::from_sval(&TestSval)),

+        );

+    }

+}

diff --git a/src/kv/value/mod.rs b/src/kv/value/mod.rs
index 1695afb..1d59dbf 100644
--- a/src/kv/value/mod.rs
+++ b/src/kv/value/mod.rs
@@ -1,155 +1,56 @@
-//! Structured values.
-
-use std::fmt;
-
-mod internal;
-mod impls;
-
-#[cfg(test)]
-pub(in kv) mod test;
-
-pub use kv::Error;
-
-use self::internal::{Inner, Visitor, Primitive};
-
-/// A type that can be converted into a [`Value`](struct.Value.html).
-pub trait ToValue {
-    /// Perform the conversion.
-    fn to_value(&self) -> Value;
-}
-
-impl<'a, T> ToValue for &'a T
-where
-    T: ToValue + ?Sized,
-{
-    fn to_value(&self) -> Value {
-        (**self).to_value()
-    }
-}
-
-impl<'v> ToValue for Value<'v> {
-    fn to_value(&self) -> Value {
-        Value {
-            inner: self.inner,
-        }
-    }
-}
-
-/// A type that requires extra work to convert into a [`Value`](struct.Value.html).
-/// 
-/// This trait is a more advanced initialization API than [`ToValue`](trait.ToValue.html).
-/// It's intended for erased values coming from other logging frameworks that may need
-/// to perform extra work to determine the concrete type to use.
-pub trait Fill {
-    /// Fill a value.
-    fn fill(&self, slot: &mut Slot) -> Result<(), Error>;
-}
-
-impl<'a, T> Fill for &'a T
-where
-    T: Fill + ?Sized,
-{
-    fn fill(&self, slot: &mut Slot) -> Result<(), Error> {
-        (**self).fill(slot)
-    }
-}
-
-/// A value slot to fill using the [`Fill`](trait.Fill.html) trait.
-pub struct Slot<'a> {
-    filled: bool,
-    visitor: &'a mut Visitor,
-}
-
-impl<'a> fmt::Debug for Slot<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        f.debug_struct("Slot").finish()
-    }
-}
-
-impl<'a> Slot<'a> {
-    fn new(visitor: &'a mut Visitor) -> Self {
-        Slot {
-            visitor,
-            filled: false,
-        }
-    }
-
-    /// Fill the slot with a value.
-    /// 
-    /// The given value doesn't need to satisfy any particular lifetime constraints.
-    /// 
-    /// # Panics
-    /// 
-    /// Calling `fill` more than once will panic.
-    pub fn fill(&mut self, value: Value) -> Result<(), Error> {
-        assert!(!self.filled, "the slot has already been filled");
-        self.filled = true;
-
-        value.visit(self.visitor)
-    }
-}
-
-/// A value in a structured key-value pair.
-pub struct Value<'v> {
-    inner: Inner<'v>,
-}
-
-impl<'v> Value<'v> {
-    /// Get a value from an internal `Visit`.
-    fn from_primitive(value: Primitive<'v>) -> Self {
-        Value {
-            inner: Inner::Primitive(value),
-        }
-    }
-
-    /// Get a value from a fillable slot.
-    pub fn from_fill<T>(value: &'v T) -> Self
-    where
-        T: Fill,
-    {
-        Value {
-            inner: Inner::Fill(value),
-        }
-    }
-
-    fn visit(&self, visitor: &mut Visitor) -> Result<(), Error> {
-        self.inner.visit(visitor)
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    #[test]
-    fn fill_value() {
-        struct TestFill;
-
-        impl Fill for TestFill {
-            fn fill(&self, slot: &mut Slot) -> Result<(), Error> {
-                let dbg: &fmt::Debug = &1;
-
-                slot.fill(Value::from_debug(&dbg))
-            }
-        }
-
-        assert_eq!("1", Value::from_fill(&TestFill).to_string());
-    }
-
-    #[test]
-    #[should_panic]
-    fn fill_multiple_times_panics() {
-        struct BadFill;
-
-        impl Fill for BadFill {
-            fn fill(&self, slot: &mut Slot) -> Result<(), Error> {
-                slot.fill(42.into())?;
-                slot.fill(6789.into())?;
-
-                Ok(())
-            }
-        }
-
-        let _ = Value::from_fill(&BadFill).to_string();
-    }
-}
+//! Structured values.

+

+mod fill;

+mod impls;

+mod internal;

+

+#[cfg(test)]

+pub(in kv) mod test;

+

+pub use self::fill::{Fill, Slot};

+pub use kv::Error;

+

+use self::internal::{Inner, Primitive, Visitor};

+

+/// A type that can be converted into a [`Value`](struct.Value.html).

+pub trait ToValue {

+    /// Perform the conversion.

+    fn to_value(&self) -> Value;

+}

+

+impl<'a, T> ToValue for &'a T

+where

+    T: ToValue + ?Sized,

+{

+    fn to_value(&self) -> Value {

+        (**self).to_value()

+    }

+}

+

+impl<'v> ToValue for Value<'v> {

+    fn to_value(&self) -> Value {

+        Value { inner: self.inner }

+    }

+}

+

+/// A value in a structured key-value pair.

+pub struct Value<'v> {

+    inner: Inner<'v>,

+}

+

+impl<'v> Value<'v> {

+    /// Get a value from an internal primitive.

+    fn from_primitive<T>(value: T) -> Self

+    where

+        T: Into<Primitive<'v>>,

+    {

+        Value {

+            inner: Inner::Primitive(value.into()),

+        }

+    }

+

+    /// Visit the value using an internal visitor.

+    fn visit<'a>(&'a self, visitor: &mut dyn Visitor<'a>) -> Result<(), Error> {

+        self.inner.visit(visitor)

+    }

+}

diff --git a/src/kv/value/test.rs b/src/kv/value/test.rs
index c9c03dc..c8d6d5c 100644
--- a/src/kv/value/test.rs
+++ b/src/kv/value/test.rs
@@ -1,81 +1,81 @@
-// Test support for inspecting Values
-
-use std::fmt;
-use std::str;
-
-use super::{Value, Error};
-use super::internal;
-
-#[derive(Debug, PartialEq)]
-pub(in kv) enum Token {
-    U64(u64),
-    I64(i64),
-    F64(f64),
-    Char(char),
-    Bool(bool),
-    Str(String),
-    None,
-
-    #[cfg(feature = "kv_unstable_sval")]
-    Sval,
-}
-
-#[cfg(test)]
-impl<'v> Value<'v> {
-    pub(in kv) fn to_token(&self) -> Token {
-        struct TestVisitor(Option<Token>);
-
-        impl internal::Visitor for TestVisitor {
-            fn debug(&mut self, v: &fmt::Debug) -> Result<(), Error> {
-                self.0 = Some(Token::Str(format!("{:?}", v)));
-                Ok(())
-            }
-
-            fn u64(&mut self, v: u64) -> Result<(), Error> {
-                self.0 = Some(Token::U64(v));
-                Ok(())
-            }
-
-            fn i64(&mut self, v: i64) -> Result<(), Error> {
-                self.0 = Some(Token::I64(v));
-                Ok(())
-            }
-
-            fn f64(&mut self, v: f64) -> Result<(), Error> {
-                self.0 = Some(Token::F64(v));
-                Ok(())
-            }
-
-            fn bool(&mut self, v: bool) -> Result<(), Error> {
-                self.0 = Some(Token::Bool(v));
-                Ok(())
-            }
-
-            fn char(&mut self, v: char) -> Result<(), Error> {
-                self.0 = Some(Token::Char(v));
-                Ok(())
-            }
-
-            fn str(&mut self, v: &str) -> Result<(), Error> {
-                self.0 = Some(Token::Str(v.into()));
-                Ok(())
-            }
-
-            fn none(&mut self) -> Result<(), Error> {
-                self.0 = Some(Token::None);
-                Ok(())
-            }
-
-            #[cfg(feature = "kv_unstable_sval")]
-            fn sval(&mut self, _: &internal::sval_support::Value) -> Result<(), Error> {
-                self.0 = Some(Token::Sval);
-                Ok(())
-            }
-        }
-
-        let mut visitor = TestVisitor(None);
-        self.visit(&mut visitor).unwrap();
-
-        visitor.0.unwrap()
-    }
-}
+// Test support for inspecting Values

+

+use std::fmt;

+use std::str;

+

+use super::internal;

+use super::{Error, Value};

+

+#[derive(Debug, PartialEq)]

+pub(in kv) enum Token {

+    U64(u64),

+    I64(i64),

+    F64(f64),

+    Char(char),

+    Bool(bool),

+    Str(String),

+    None,

+

+    #[cfg(feature = "kv_unstable_sval")]

+    Sval,

+}

+

+#[cfg(test)]

+impl<'v> Value<'v> {

+    pub(in kv) fn to_token(&self) -> Token {

+        struct TestVisitor(Option<Token>);

+

+        impl<'v> internal::Visitor<'v> for TestVisitor {

+            fn debug(&mut self, v: &dyn fmt::Debug) -> Result<(), Error> {

+                self.0 = Some(Token::Str(format!("{:?}", v)));

+                Ok(())

+            }

+

+            fn u64(&mut self, v: u64) -> Result<(), Error> {

+                self.0 = Some(Token::U64(v));

+                Ok(())

+            }

+

+            fn i64(&mut self, v: i64) -> Result<(), Error> {

+                self.0 = Some(Token::I64(v));

+                Ok(())

+            }

+

+            fn f64(&mut self, v: f64) -> Result<(), Error> {

+                self.0 = Some(Token::F64(v));

+                Ok(())

+            }

+

+            fn bool(&mut self, v: bool) -> Result<(), Error> {

+                self.0 = Some(Token::Bool(v));

+                Ok(())

+            }

+

+            fn char(&mut self, v: char) -> Result<(), Error> {

+                self.0 = Some(Token::Char(v));

+                Ok(())

+            }

+

+            fn str(&mut self, v: &str) -> Result<(), Error> {

+                self.0 = Some(Token::Str(v.into()));

+                Ok(())

+            }

+

+            fn none(&mut self) -> Result<(), Error> {

+                self.0 = Some(Token::None);

+                Ok(())

+            }

+

+            #[cfg(feature = "kv_unstable_sval")]

+            fn sval(&mut self, _: &dyn internal::sval::Value) -> Result<(), Error> {

+                self.0 = Some(Token::Sval);

+                Ok(())

+            }

+        }

+

+        let mut visitor = TestVisitor(None);

+        self.visit(&mut visitor).unwrap();

+

+        visitor.0.unwrap()

+    }

+}

diff --git a/src/lib.rs b/src/lib.rs
index c79219d..83b78d0 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -1,1668 +1,1679 @@
-// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-//! A lightweight logging facade.
-//!
-//! The `log` crate provides a single logging API that abstracts over the
-//! actual logging implementation. Libraries can use the logging API provided
-//! by this crate, and the consumer of those libraries can choose the logging
-//! implementation that is most suitable for its use case.
-//!
-//! If no logging implementation is selected, the facade falls back to a "noop"
-//! implementation that ignores all log messages. The overhead in this case
-//! is very small - just an integer load, comparison and jump.
-//!
-//! A log request consists of a _target_, a _level_, and a _body_. A target is a
-//! string which defaults to the module path of the location of the log request,
-//! though that default may be overridden. Logger implementations typically use
-//! the target to filter requests based on some user configuration.
-//!
-//! # Use
-//!
-//! The basic use of the log crate is through the five logging macros: [`error!`],
-//! [`warn!`], [`info!`], [`debug!`] and [`trace!`]
-//! where `error!` represents the highest-priority log messages
-//! and `trace!` the lowest. The log messages are filtered by configuring
-//! the log level to exclude messages with a lower priority.
-//! Each of these macros accept format strings similarly to [`println!`].
-//!
-//!
-//! [`error!`]: ./macro.error.html
-//! [`warn!`]: ./macro.warn.html
-//! [`info!`]: ./macro.info.html
-//! [`debug!`]: ./macro.debug.html
-//! [`trace!`]: ./macro.trace.html
-//! [`println!`]: https://doc.rust-lang.org/stable/std/macro.println.html
-//!
-//! ## In libraries
-//!
-//! Libraries should link only to the `log` crate, and use the provided
-//! macros to log whatever information will be useful to downstream consumers.
-//!
-//! ### Examples
-//!
-//! ```edition2018
-//! # #[derive(Debug)] pub struct Yak(String);
-//! # impl Yak { fn shave(&mut self, _: u32) {} }
-//! # fn find_a_razor() -> Result<u32, u32> { Ok(1) }
-//! use log::{info, warn};
-//!
-//! pub fn shave_the_yak(yak: &mut Yak) {
-//!     info!(target: "yak_events", "Commencing yak shaving for {:?}", yak);
-//!
-//!     loop {
-//!         match find_a_razor() {
-//!             Ok(razor) => {
-//!                 info!("Razor located: {}", razor);
-//!                 yak.shave(razor);
-//!                 break;
-//!             }
-//!             Err(err) => {
-//!                 warn!("Unable to locate a razor: {}, retrying", err);
-//!             }
-//!         }
-//!     }
-//! }
-//! # fn main() {}
-//! ```
-//!
-//! ## In executables
-//!
-//! Executables should choose a logging implementation and initialize it early in the
-//! runtime of the program. Logging implementations will typically include a
-//! function to do this. Any log messages generated before
-//! the implementation is initialized will be ignored.
-//!
-//! The executable itself may use the `log` crate to log as well.
-//!
-//! ### Warning
-//!
-//! The logging system may only be initialized once.
-//!
-//! # Available logging implementations
-//!
-//! In order to produce log output executables have to use
-//! a logger implementation compatible with the facade.
-//! There are many available implementations to choose from,
-//! here are some of the most popular ones:
-//!
-//! * Simple minimal loggers:
-//!     * [env_logger]
-//!     * [simple_logger]
-//!     * [simplelog]
-//!     * [pretty_env_logger]
-//!     * [stderrlog]
-//!     * [flexi_logger]
-//! * Complex configurable frameworks:
-//!     * [log4rs]
-//!     * [fern]
-//! * Adaptors for other facilities:
-//!     * [syslog]
-//!     * [slog-stdlog]
-//!
-//! # Implementing a Logger
-//!
-//! Loggers implement the [`Log`] trait. Here's a very basic example that simply
-//! logs all messages at the [`Error`][level_link], [`Warn`][level_link] or
-//! [`Info`][level_link] levels to stdout:
-//!
-//! ```edition2018
-//! use log::{Record, Level, Metadata};
-//!
-//! struct SimpleLogger;
-//!
-//! impl log::Log for SimpleLogger {
-//!     fn enabled(&self, metadata: &Metadata) -> bool {
-//!         metadata.level() <= Level::Info
-//!     }
-//!
-//!     fn log(&self, record: &Record) {
-//!         if self.enabled(record.metadata()) {
-//!             println!("{} - {}", record.level(), record.args());
-//!         }
-//!     }
-//!
-//!     fn flush(&self) {}
-//! }
-//!
-//! # fn main() {}
-//! ```
-//!
-//! Loggers are installed by calling the [`set_logger`] function. The maximum
-//! log level also needs to be adjusted via the [`set_max_level`] function. The
-//! logging facade uses this as an optimization to improve performance of log
-//! messages at levels that are disabled. It's important to set it, as it
-//! defaults to [`Off`][filter_link], so no log messages will ever be captured!
-//! In the case of our example logger, we'll want to set the maximum log level
-//! to [`Info`][filter_link], since we ignore any [`Debug`][level_link] or
-//! [`Trace`][level_link] level log messages. A logging implementation should
-//! provide a function that wraps a call to [`set_logger`] and
-//! [`set_max_level`], handling initialization of the logger:
-//!
-//! ```edition2018
-//! # use log::{Level, Metadata};
-//! # struct SimpleLogger;
-//! # impl log::Log for SimpleLogger {
-//! #   fn enabled(&self, _: &Metadata) -> bool { false }
-//! #   fn log(&self, _: &log::Record) {}
-//! #   fn flush(&self) {}
-//! # }
-//! # fn main() {}
-//! use log::{SetLoggerError, LevelFilter};
-//!
-//! static LOGGER: SimpleLogger = SimpleLogger;
-//!
-//! pub fn init() -> Result<(), SetLoggerError> {
-//!     log::set_logger(&LOGGER)
-//!         .map(|()| log::set_max_level(LevelFilter::Info))
-//! }
-//! ```
-//!
-//! Implementations that adjust their configurations at runtime should take care
-//! to adjust the maximum log level as well.
-//!
-//! # Use with `std`
-//!
-//! `set_logger` requires you to provide a `&'static Log`, which can be hard to
-//! obtain if your logger depends on some runtime configuration. The
-//! `set_boxed_logger` function is available with the `std` Cargo feature. It is
-//! identical to `set_logger` except that it takes a `Box<Log>` rather than a
-//! `&'static Log`:
-//!
-//! ```edition2018
-//! # use log::{Level, LevelFilter, Log, SetLoggerError, Metadata};
-//! # struct SimpleLogger;
-//! # impl log::Log for SimpleLogger {
-//! #   fn enabled(&self, _: &Metadata) -> bool { false }
-//! #   fn log(&self, _: &log::Record) {}
-//! #   fn flush(&self) {}
-//! # }
-//! # fn main() {}
-//! # #[cfg(feature = "std")]
-//! pub fn init() -> Result<(), SetLoggerError> {
-//!     log::set_boxed_logger(Box::new(SimpleLogger))
-//!         .map(|()| log::set_max_level(LevelFilter::Info))
-//! }
-//! ```
-//!
-//! # Compile time filters
-//!
-//! Log levels can be statically disabled at compile time via Cargo features. Log invocations at
-//! disabled levels will be skipped and will not even be present in the resulting binary unless the
-//! log level is specified dynamically. This level is configured separately for release and debug
-//! builds. The features are:
-//!
-//! * `max_level_off`
-//! * `max_level_error`
-//! * `max_level_warn`
-//! * `max_level_info`
-//! * `max_level_debug`
-//! * `max_level_trace`
-//! * `release_max_level_off`
-//! * `release_max_level_error`
-//! * `release_max_level_warn`
-//! * `release_max_level_info`
-//! * `release_max_level_debug`
-//! * `release_max_level_trace`
-//!
-//! These features control the value of the `STATIC_MAX_LEVEL` constant. The logging macros check
-//! this value before logging a message. By default, no levels are disabled.
-//!
-//! Libraries should avoid using the max level features because they're global and can't be changed
-//! once they're set.
-//!
-//! For example, a crate can disable trace level logs in debug builds and trace, debug, and info
-//! level logs in release builds with the following configuration:
-//!
-//! ```toml
-//! [dependencies]
-//! log = { version = "0.4", features = ["max_level_debug", "release_max_level_warn"] }
-//! ```
-//! # Crate Feature Flags
-//!
-//! The following crate feature flags are avaliable in addition to the filters. They are
-//! configured in your `Cargo.toml`.
-//!
-//! * `std` allows use of `std` crate instead of the default `core`. Enables using `std::error` and
-//! `set_boxed_logger` functionality.
-//! * `serde` enables support for serialization and deserialization of `Level` and `LevelFilter`.
-//!
-//! ```toml
-//! [dependencies]
-//! log = { version = "0.4", features = ["std", "serde"] }
-//! ```
-//!
-//! # Version compatibility
-//!
-//! The 0.3 and 0.4 versions of the `log` crate are almost entirely compatible. Log messages
-//! made using `log` 0.3 will forward transparently to a logger implementation using `log` 0.4. Log
-//! messages made using `log` 0.4 will forward to a logger implementation using `log` 0.3, but the
-//! module path and file name information associated with the message will unfortunately be lost.
-//!
-//! [`Log`]: trait.Log.html
-//! [level_link]: enum.Level.html
-//! [filter_link]: enum.LevelFilter.html
-//! [`set_logger`]: fn.set_logger.html
-//! [`set_max_level`]: fn.set_max_level.html
-//! [`try_set_logger_raw`]: fn.try_set_logger_raw.html
-//! [`shutdown_logger_raw`]: fn.shutdown_logger_raw.html
-//! [env_logger]: https://docs.rs/env_logger/*/env_logger/
-//! [simple_logger]: https://github.com/borntyping/rust-simple_logger
-//! [simplelog]: https://github.com/drakulix/simplelog.rs
-//! [pretty_env_logger]: https://docs.rs/pretty_env_logger/*/pretty_env_logger/
-//! [stderrlog]: https://docs.rs/stderrlog/*/stderrlog/
-//! [flexi_logger]: https://docs.rs/flexi_logger/*/flexi_logger/
-//! [syslog]: https://docs.rs/syslog/*/syslog/
-//! [slog-stdlog]: https://docs.rs/slog-stdlog/*/slog_stdlog/
-//! [log4rs]: https://docs.rs/log4rs/*/log4rs/
-//! [fern]: https://docs.rs/fern/*/fern/
-
-#![doc(
-    html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",
-    html_favicon_url = "https://www.rust-lang.org/favicon.ico",
-    html_root_url = "https://docs.rs/log/0.4.8"
-)]
-#![warn(missing_docs)]
-#![deny(missing_debug_implementations)]
-#![cfg_attr(all(not(feature = "std"), not(test)), no_std)]
-// When compiled for the rustc compiler itself we want to make sure that this is
-// an unstable crate
-#![cfg_attr(rustbuild, feature(staged_api, rustc_private))]
-#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]
-
-#[cfg(all(not(feature = "std"), not(test)))]
-extern crate core as std;
-
-#[macro_use]
-extern crate cfg_if;
-
-use std::cmp;
-#[cfg(feature = "std")]
-use std::error;
-use std::fmt;
-use std::mem;
-use std::str::FromStr;
-use std::sync::atomic::{AtomicUsize, Ordering};
-
-// FIXME: ATOMIC_USIZE_INIT was deprecated in rust 1.34. Silence the
-// deprecation warning until our MSRV >= 1.24, where we can use the
-// replacement const fn `AtomicUsize::new`
-#[allow(deprecated)]
-use std::sync::atomic::ATOMIC_USIZE_INIT;
-
-#[macro_use]
-mod macros;
-mod serde;
-
-#[cfg(feature = "kv_unstable")]
-pub mod kv;
-
-// The LOGGER static holds a pointer to the global logger. It is protected by
-// the STATE static which determines whether LOGGER has been initialized yet.
-static mut LOGGER: &'static Log = &NopLogger;
-
-#[allow(deprecated)]
-static STATE: AtomicUsize = ATOMIC_USIZE_INIT;
-
-// There are three different states that we care about: the logger's
-// uninitialized, the logger's initializing (set_logger's been called but
-// LOGGER hasn't actually been set yet), or the logger's active.
-const UNINITIALIZED: usize = 0;
-const INITIALIZING: usize = 1;
-const INITIALIZED: usize = 2;
-
-#[allow(deprecated)]
-static MAX_LOG_LEVEL_FILTER: AtomicUsize = ATOMIC_USIZE_INIT;
-
-static LOG_LEVEL_NAMES: [&'static str; 6] = ["OFF", "ERROR", "WARN", "INFO", "DEBUG", "TRACE"];
-
-static SET_LOGGER_ERROR: &'static str = "attempted to set a logger after the logging system \
-                                         was already initialized";
-static LEVEL_PARSE_ERROR: &'static str =
-    "attempted to convert a string that doesn't match an existing log level";
-
-/// An enum representing the available verbosity levels of the logger.
-///
-/// Typical usage includes: checking if a certain `Level` is enabled with
-/// [`log_enabled!`](macro.log_enabled.html), specifying the `Level` of
-/// [`log!`](macro.log.html), and comparing a `Level` directly to a
-/// [`LevelFilter`](enum.LevelFilter.html).
-#[repr(usize)]
-#[derive(Copy, Eq, Debug, Hash)]
-pub enum Level {
-    /// The "error" level.
-    ///
-    /// Designates very serious errors.
-    Error = 1, // This way these line up with the discriminants for LevelFilter below
-    /// The "warn" level.
-    ///
-    /// Designates hazardous situations.
-    Warn,
-    /// The "info" level.
-    ///
-    /// Designates useful information.
-    Info,
-    /// The "debug" level.
-    ///
-    /// Designates lower priority information.
-    Debug,
-    /// The "trace" level.
-    ///
-    /// Designates very low priority, often extremely verbose, information.
-    Trace,
-}
-
-impl Clone for Level {
-    #[inline]
-    fn clone(&self) -> Level {
-        *self
-    }
-}
-
-impl PartialEq for Level {
-    #[inline]
-    fn eq(&self, other: &Level) -> bool {
-        *self as usize == *other as usize
-    }
-}
-
-impl PartialEq<LevelFilter> for Level {
-    #[inline]
-    fn eq(&self, other: &LevelFilter) -> bool {
-        *self as usize == *other as usize
-    }
-}
-
-impl PartialOrd for Level {
-    #[inline]
-    fn partial_cmp(&self, other: &Level) -> Option<cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-
-    #[inline]
-    fn lt(&self, other: &Level) -> bool {
-        (*self as usize) < *other as usize
-    }
-
-    #[inline]
-    fn le(&self, other: &Level) -> bool {
-        *self as usize <= *other as usize
-    }
-
-    #[inline]
-    fn gt(&self, other: &Level) -> bool {
-        *self as usize > *other as usize
-    }
-
-    #[inline]
-    fn ge(&self, other: &Level) -> bool {
-        *self as usize >= *other as usize
-    }
-}
-
-impl PartialOrd<LevelFilter> for Level {
-    #[inline]
-    fn partial_cmp(&self, other: &LevelFilter) -> Option<cmp::Ordering> {
-        Some((*self as usize).cmp(&(*other as usize)))
-    }
-
-    #[inline]
-    fn lt(&self, other: &LevelFilter) -> bool {
-        (*self as usize) < *other as usize
-    }
-
-    #[inline]
-    fn le(&self, other: &LevelFilter) -> bool {
-        *self as usize <= *other as usize
-    }
-
-    #[inline]
-    fn gt(&self, other: &LevelFilter) -> bool {
-        *self as usize > *other as usize
-    }
-
-    #[inline]
-    fn ge(&self, other: &LevelFilter) -> bool {
-        *self as usize >= *other as usize
-    }
-}
-
-impl Ord for Level {
-    #[inline]
-    fn cmp(&self, other: &Level) -> cmp::Ordering {
-        (*self as usize).cmp(&(*other as usize))
-    }
-}
-
-fn ok_or<T, E>(t: Option<T>, e: E) -> Result<T, E> {
-    match t {
-        Some(t) => Ok(t),
-        None => Err(e),
-    }
-}
-
-// Reimplemented here because std::ascii is not available in libcore
-fn eq_ignore_ascii_case(a: &str, b: &str) -> bool {
-    fn to_ascii_uppercase(c: u8) -> u8 {
-        if c >= b'a' && c <= b'z' {
-            c - b'a' + b'A'
-        } else {
-            c
-        }
-    }
-
-    if a.len() == b.len() {
-        a.bytes()
-            .zip(b.bytes())
-            .all(|(a, b)| to_ascii_uppercase(a) == to_ascii_uppercase(b))
-    } else {
-        false
-    }
-}
-
-impl FromStr for Level {
-    type Err = ParseLevelError;
-    fn from_str(level: &str) -> Result<Level, Self::Err> {
-        ok_or(
-            LOG_LEVEL_NAMES
-                .iter()
-                .position(|&name| eq_ignore_ascii_case(name, level))
-                .into_iter()
-                .filter(|&idx| idx != 0)
-                .map(|idx| Level::from_usize(idx).unwrap())
-                .next(),
-            ParseLevelError(()),
-        )
-    }
-}
-
-impl fmt::Display for Level {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        fmt.pad(LOG_LEVEL_NAMES[*self as usize])
-    }
-}
-
-impl Level {
-    fn from_usize(u: usize) -> Option<Level> {
-        match u {
-            1 => Some(Level::Error),
-            2 => Some(Level::Warn),
-            3 => Some(Level::Info),
-            4 => Some(Level::Debug),
-            5 => Some(Level::Trace),
-            _ => None,
-        }
-    }
-
-    /// Returns the most verbose logging level.
-    #[inline]
-    pub fn max() -> Level {
-        Level::Trace
-    }
-
-    /// Converts the `Level` to the equivalent `LevelFilter`.
-    #[inline]
-    pub fn to_level_filter(&self) -> LevelFilter {
-        LevelFilter::from_usize(*self as usize).unwrap()
-    }
-}
-
-/// An enum representing the available verbosity level filters of the logger.
-///
-/// A `LevelFilter` may be compared directly to a [`Level`]. Use this type
-/// to get and set the maximum log level with [`max_level()`] and [`set_max_level`].
-///
-/// [`Level`]: enum.Level.html
-/// [`max_level()`]: fn.max_level.html
-/// [`set_max_level`]: fn.set_max_level.html
-#[repr(usize)]
-#[derive(Copy, Eq, Debug, Hash)]
-pub enum LevelFilter {
-    /// A level lower than all log levels.
-    Off,
-    /// Corresponds to the `Error` log level.
-    Error,
-    /// Corresponds to the `Warn` log level.
-    Warn,
-    /// Corresponds to the `Info` log level.
-    Info,
-    /// Corresponds to the `Debug` log level.
-    Debug,
-    /// Corresponds to the `Trace` log level.
-    Trace,
-}
-
-// Deriving generates terrible impls of these traits
-
-impl Clone for LevelFilter {
-    #[inline]
-    fn clone(&self) -> LevelFilter {
-        *self
-    }
-}
-
-impl PartialEq for LevelFilter {
-    #[inline]
-    fn eq(&self, other: &LevelFilter) -> bool {
-        *self as usize == *other as usize
-    }
-}
-
-impl PartialEq<Level> for LevelFilter {
-    #[inline]
-    fn eq(&self, other: &Level) -> bool {
-        other.eq(self)
-    }
-}
-
-impl PartialOrd for LevelFilter {
-    #[inline]
-    fn partial_cmp(&self, other: &LevelFilter) -> Option<cmp::Ordering> {
-        Some(self.cmp(other))
-    }
-
-    #[inline]
-    fn lt(&self, other: &LevelFilter) -> bool {
-        (*self as usize) < *other as usize
-    }
-
-    #[inline]
-    fn le(&self, other: &LevelFilter) -> bool {
-        *self as usize <= *other as usize
-    }
-
-    #[inline]
-    fn gt(&self, other: &LevelFilter) -> bool {
-        *self as usize > *other as usize
-    }
-
-    #[inline]
-    fn ge(&self, other: &LevelFilter) -> bool {
-        *self as usize >= *other as usize
-    }
-}
-
-impl PartialOrd<Level> for LevelFilter {
-    #[inline]
-    fn partial_cmp(&self, other: &Level) -> Option<cmp::Ordering> {
-        Some((*self as usize).cmp(&(*other as usize)))
-    }
-
-    #[inline]
-    fn lt(&self, other: &Level) -> bool {
-        (*self as usize) < *other as usize
-    }
-
-    #[inline]
-    fn le(&self, other: &Level) -> bool {
-        *self as usize <= *other as usize
-    }
-
-    #[inline]
-    fn gt(&self, other: &Level) -> bool {
-        *self as usize > *other as usize
-    }
-
-    #[inline]
-    fn ge(&self, other: &Level) -> bool {
-        *self as usize >= *other as usize
-    }
-}
-
-impl Ord for LevelFilter {
-    #[inline]
-    fn cmp(&self, other: &LevelFilter) -> cmp::Ordering {
-        (*self as usize).cmp(&(*other as usize))
-    }
-}
-
-impl FromStr for LevelFilter {
-    type Err = ParseLevelError;
-    fn from_str(level: &str) -> Result<LevelFilter, Self::Err> {
-        ok_or(
-            LOG_LEVEL_NAMES
-                .iter()
-                .position(|&name| eq_ignore_ascii_case(name, level))
-                .map(|p| LevelFilter::from_usize(p).unwrap()),
-            ParseLevelError(()),
-        )
-    }
-}
-
-impl fmt::Display for LevelFilter {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        fmt.pad(LOG_LEVEL_NAMES[*self as usize])
-    }
-}
-
-impl LevelFilter {
-    fn from_usize(u: usize) -> Option<LevelFilter> {
-        match u {
-            0 => Some(LevelFilter::Off),
-            1 => Some(LevelFilter::Error),
-            2 => Some(LevelFilter::Warn),
-            3 => Some(LevelFilter::Info),
-            4 => Some(LevelFilter::Debug),
-            5 => Some(LevelFilter::Trace),
-            _ => None,
-        }
-    }
-    /// Returns the most verbose logging level filter.
-    #[inline]
-    pub fn max() -> LevelFilter {
-        LevelFilter::Trace
-    }
-
-    /// Converts `self` to the equivalent `Level`.
-    ///
-    /// Returns `None` if `self` is `LevelFilter::Off`.
-    #[inline]
-    pub fn to_level(&self) -> Option<Level> {
-        Level::from_usize(*self as usize)
-    }
-}
-
-#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
-enum MaybeStaticStr<'a> {
-    Static(&'static str),
-    Borrowed(&'a str),
-}
-
-impl<'a> MaybeStaticStr<'a> {
-    #[inline]
-    fn get(&self) -> &'a str {
-        match *self {
-            MaybeStaticStr::Static(s) => s,
-            MaybeStaticStr::Borrowed(s) => s,
-        }
-    }
-}
-
-/// The "payload" of a log message.
-///
-/// # Use
-///
-/// `Record` structures are passed as parameters to the [`log`][method.log]
-/// method of the [`Log`] trait. Logger implementors manipulate these
-/// structures in order to display log messages. `Record`s are automatically
-/// created by the [`log!`] macro and so are not seen by log users.
-///
-/// Note that the [`level()`] and [`target()`] accessors are equivalent to
-/// `self.metadata().level()` and `self.metadata().target()` respectively.
-/// These methods are provided as a convenience for users of this structure.
-///
-/// # Example
-///
-/// The following example shows a simple logger that displays the level,
-/// module path, and message of any `Record` that is passed to it.
-///
-/// ```edition2018
-/// struct SimpleLogger;
-///
-/// impl log::Log for SimpleLogger {
-///    fn enabled(&self, metadata: &log::Metadata) -> bool {
-///        true
-///    }
-///
-///    fn log(&self, record: &log::Record) {
-///        if !self.enabled(record.metadata()) {
-///            return;
-///        }
-///
-///        println!("{}:{} -- {}",
-///                 record.level(),
-///                 record.target(),
-///                 record.args());
-///    }
-///    fn flush(&self) {}
-/// }
-/// ```
-///
-/// [method.log]: trait.Log.html#tymethod.log
-/// [`Log`]: trait.Log.html
-/// [`log!`]: macro.log.html
-/// [`level()`]: struct.Record.html#method.level
-/// [`target()`]: struct.Record.html#method.target
-#[derive(Clone, Debug)]
-pub struct Record<'a> {
-    metadata: Metadata<'a>,
-    args: fmt::Arguments<'a>,
-    module_path: Option<MaybeStaticStr<'a>>,
-    file: Option<MaybeStaticStr<'a>>,
-    line: Option<u32>,
-    #[cfg(feature = "kv_unstable")]
-    key_values: KeyValues<'a>,
-}
-
-// This wrapper type is only needed so we can
-// `#[derive(Debug)]` on `Record`. It also
-// provides a useful `Debug` implementation for
-// the underlying `Source`.
-#[cfg(feature = "kv_unstable")]
-#[derive(Clone)]
-struct KeyValues<'a>(&'a kv::Source);
-
-#[cfg(feature = "kv_unstable")]
-impl<'a> fmt::Debug for KeyValues<'a> {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        let mut visitor = f.debug_map();
-        self.0.visit(&mut visitor)?;
-        visitor.finish()
-    }
-}
-
-impl<'a> Record<'a> {
-    /// Returns a new builder.
-    #[inline]
-    pub fn builder() -> RecordBuilder<'a> {
-        RecordBuilder::new()
-    }
-
-    /// The message body.
-    #[inline]
-    pub fn args(&self) -> &fmt::Arguments<'a> {
-        &self.args
-    }
-
-    /// Metadata about the log directive.
-    #[inline]
-    pub fn metadata(&self) -> &Metadata<'a> {
-        &self.metadata
-    }
-
-    /// The verbosity level of the message.
-    #[inline]
-    pub fn level(&self) -> Level {
-        self.metadata.level()
-    }
-
-    /// The name of the target of the directive.
-    #[inline]
-    pub fn target(&self) -> &'a str {
-        self.metadata.target()
-    }
-
-    /// The module path of the message.
-    #[inline]
-    pub fn module_path(&self) -> Option<&'a str> {
-        self.module_path.map(|s| s.get())
-    }
-
-    /// The module path of the message, if it is a `'static` string.
-    #[inline]
-    pub fn module_path_static(&self) -> Option<&'static str> {
-        match self.module_path {
-            Some(MaybeStaticStr::Static(s)) => Some(s),
-            _ => None,
-        }
-    }
-
-    /// The source file containing the message.
-    #[inline]
-    pub fn file(&self) -> Option<&'a str> {
-        self.file.map(|s| s.get())
-    }
-
-    /// The module path of the message, if it is a `'static` string.
-    #[inline]
-    pub fn file_static(&self) -> Option<&'static str> {
-        match self.file {
-            Some(MaybeStaticStr::Static(s)) => Some(s),
-            _ => None,
-        }
-    }
-
-    /// The line containing the message.
-    #[inline]
-    pub fn line(&self) -> Option<u32> {
-        self.line
-    }
-
-    /// The structued key-value pairs associated with the message.
-    #[cfg(feature = "kv_unstable")]
-    #[inline]
-    pub fn key_values(&self) -> &kv::Source {
-        self.key_values.0
-    }
-
-    /// Create a new [`Builder`](struct.Builder.html) based on this record.
-    #[cfg(feature = "kv_unstable")]
-    #[inline]
-    pub fn to_builder(&self) -> RecordBuilder {
-        RecordBuilder {
-            record: Record {
-                metadata: Metadata {
-                    level: self.metadata.level,
-                    target: self.metadata.target,
-                },
-                args: self.args,
-                module_path: self.module_path,
-                file: self.file,
-                line: self.line,
-                key_values: self.key_values.clone(),
-            }
-        }
-    }
-}
-
-/// Builder for [`Record`](struct.Record.html).
-///
-/// Typically should only be used by log library creators or for testing and "shim loggers".
-/// The `RecordBuilder` can set the different parameters of `Record` object, and returns
-/// the created object when `build` is called.
-///
-/// # Examples
-///
-///
-/// ```edition2018
-/// use log::{Level, Record};
-///
-/// let record = Record::builder()
-///                 .args(format_args!("Error!"))
-///                 .level(Level::Error)
-///                 .target("myApp")
-///                 .file(Some("server.rs"))
-///                 .line(Some(144))
-///                 .module_path(Some("server"))
-///                 .build();
-/// ```
-///
-/// Alternatively, use [`MetadataBuilder`](struct.MetadataBuilder.html):
-///
-/// ```edition2018
-/// use log::{Record, Level, MetadataBuilder};
-///
-/// let error_metadata = MetadataBuilder::new()
-///                         .target("myApp")
-///                         .level(Level::Error)
-///                         .build();
-///
-/// let record = Record::builder()
-///                 .metadata(error_metadata)
-///                 .args(format_args!("Error!"))
-///                 .line(Some(433))
-///                 .file(Some("app.rs"))
-///                 .module_path(Some("server"))
-///                 .build();
-/// ```
-#[derive(Debug)]
-pub struct RecordBuilder<'a> {
-    record: Record<'a>,
-}
-
-impl<'a> RecordBuilder<'a> {
-    /// Construct new `RecordBuilder`.
-    ///
-    /// The default options are:
-    ///
-    /// - `args`: [`format_args!("")`]
-    /// - `metadata`: [`Metadata::builder().build()`]
-    /// - `module_path`: `None`
-    /// - `file`: `None`
-    /// - `line`: `None`
-    ///
-    /// [`format_args!("")`]: https://doc.rust-lang.org/std/macro.format_args.html
-    /// [`Metadata::builder().build()`]: struct.MetadataBuilder.html#method.build
-    #[inline]
-    pub fn new() -> RecordBuilder<'a> {
-        #[cfg(feature = "kv_unstable")]
-        return RecordBuilder {
-            record: Record {
-                args: format_args!(""),
-                metadata: Metadata::builder().build(),
-                module_path: None,
-                file: None,
-                line: None,
-                key_values: KeyValues(&Option::None::<(kv::Key, kv::Value)>),
-            },
-        };
-
-        #[cfg(not(feature = "kv_unstable"))]
-        return RecordBuilder {
-            record: Record {
-                args: format_args!(""),
-                metadata: Metadata::builder().build(),
-                module_path: None,
-                file: None,
-                line: None,
-            },
-        };
-    }
-
-    /// Set [`args`](struct.Record.html#method.args).
-    #[inline]
-    pub fn args(&mut self, args: fmt::Arguments<'a>) -> &mut RecordBuilder<'a> {
-        self.record.args = args;
-        self
-    }
-
-    /// Set [`metadata`](struct.Record.html#method.metadata). Construct a `Metadata` object with [`MetadataBuilder`](struct.MetadataBuilder.html).
-    #[inline]
-    pub fn metadata(&mut self, metadata: Metadata<'a>) -> &mut RecordBuilder<'a> {
-        self.record.metadata = metadata;
-        self
-    }
-
-    /// Set [`Metadata::level`](struct.Metadata.html#method.level).
-    #[inline]
-    pub fn level(&mut self, level: Level) -> &mut RecordBuilder<'a> {
-        self.record.metadata.level = level;
-        self
-    }
-
-    /// Set [`Metadata::target`](struct.Metadata.html#method.target)
-    #[inline]
-    pub fn target(&mut self, target: &'a str) -> &mut RecordBuilder<'a> {
-        self.record.metadata.target = target;
-        self
-    }
-
-    /// Set [`module_path`](struct.Record.html#method.module_path)
-    #[inline]
-    pub fn module_path(&mut self, path: Option<&'a str>) -> &mut RecordBuilder<'a> {
-        self.record.module_path = path.map(MaybeStaticStr::Borrowed);
-        self
-    }
-
-    /// Set [`module_path`](struct.Record.html#method.module_path) to a `'static` string
-    #[inline]
-    pub fn module_path_static(&mut self, path: Option<&'static str>) -> &mut RecordBuilder<'a> {
-        self.record.module_path = path.map(MaybeStaticStr::Static);
-        self
-    }
-
-    /// Set [`file`](struct.Record.html#method.file)
-    #[inline]
-    pub fn file(&mut self, file: Option<&'a str>) -> &mut RecordBuilder<'a> {
-        self.record.file = file.map(MaybeStaticStr::Borrowed);
-        self
-    }
-
-    /// Set [`file`](struct.Record.html#method.file) to a `'static` string.
-    #[inline]
-    pub fn file_static(&mut self, file: Option<&'static str>) -> &mut RecordBuilder<'a> {
-        self.record.file = file.map(MaybeStaticStr::Static);
-        self
-    }
-
-    /// Set [`line`](struct.Record.html#method.line)
-    #[inline]
-    pub fn line(&mut self, line: Option<u32>) -> &mut RecordBuilder<'a> {
-        self.record.line = line;
-        self
-    }
-
-    /// Set [`key_values`](struct.Record.html#method.key_values)
-    #[cfg(feature = "kv_unstable")]
-    #[inline]
-    pub fn key_values(&mut self, kvs: &'a kv::Source) -> &mut RecordBuilder<'a> {
-        self.record.key_values = KeyValues(kvs);
-        self
-    }
-
-    /// Invoke the builder and return a `Record`
-    #[inline]
-    pub fn build(&self) -> Record<'a> {
-        self.record.clone()
-    }
-}
-
-/// Metadata about a log message.
-///
-/// # Use
-///
-/// `Metadata` structs are created when users of the library use
-/// logging macros.
-///
-/// They are consumed by implementations of the `Log` trait in the
-/// `enabled` method.
-///
-/// `Record`s use `Metadata` to determine the log message's severity
-/// and target.
-///
-/// Users should use the `log_enabled!` macro in their code to avoid
-/// constructing expensive log messages.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::{Record, Level, Metadata};
-///
-/// struct MyLogger;
-///
-/// impl log::Log for MyLogger {
-///     fn enabled(&self, metadata: &Metadata) -> bool {
-///         metadata.level() <= Level::Info
-///     }
-///
-///     fn log(&self, record: &Record) {
-///         if self.enabled(record.metadata()) {
-///             println!("{} - {}", record.level(), record.args());
-///         }
-///     }
-///     fn flush(&self) {}
-/// }
-///
-/// # fn main(){}
-/// ```
-#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
-pub struct Metadata<'a> {
-    level: Level,
-    target: &'a str,
-}
-
-impl<'a> Metadata<'a> {
-    /// Returns a new builder.
-    #[inline]
-    pub fn builder() -> MetadataBuilder<'a> {
-        MetadataBuilder::new()
-    }
-
-    /// The verbosity level of the message.
-    #[inline]
-    pub fn level(&self) -> Level {
-        self.level
-    }
-
-    /// The name of the target of the directive.
-    #[inline]
-    pub fn target(&self) -> &'a str {
-        self.target
-    }
-}
-
-/// Builder for [`Metadata`](struct.Metadata.html).
-///
-/// Typically should only be used by log library creators or for testing and "shim loggers".
-/// The `MetadataBuilder` can set the different parameters of a `Metadata` object, and returns
-/// the created object when `build` is called.
-///
-/// # Example
-///
-/// ```edition2018
-/// let target = "myApp";
-/// use log::{Level, MetadataBuilder};
-/// let metadata = MetadataBuilder::new()
-///                     .level(Level::Debug)
-///                     .target(target)
-///                     .build();
-/// ```
-#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]
-pub struct MetadataBuilder<'a> {
-    metadata: Metadata<'a>,
-}
-
-impl<'a> MetadataBuilder<'a> {
-    /// Construct a new `MetadataBuilder`.
-    ///
-    /// The default options are:
-    ///
-    /// - `level`: `Level::Info`
-    /// - `target`: `""`
-    #[inline]
-    pub fn new() -> MetadataBuilder<'a> {
-        MetadataBuilder {
-            metadata: Metadata {
-                level: Level::Info,
-                target: "",
-            },
-        }
-    }
-
-    /// Setter for [`level`](struct.Metadata.html#method.level).
-    #[inline]
-    pub fn level(&mut self, arg: Level) -> &mut MetadataBuilder<'a> {
-        self.metadata.level = arg;
-        self
-    }
-
-    /// Setter for [`target`](struct.Metadata.html#method.target).
-    #[inline]
-    pub fn target(&mut self, target: &'a str) -> &mut MetadataBuilder<'a> {
-        self.metadata.target = target;
-        self
-    }
-
-    /// Returns a `Metadata` object.
-    #[inline]
-    pub fn build(&self) -> Metadata<'a> {
-        self.metadata.clone()
-    }
-}
-
-/// A trait encapsulating the operations required of a logger.
-pub trait Log: Sync + Send {
-    /// Determines if a log message with the specified metadata would be
-    /// logged.
-    ///
-    /// This is used by the `log_enabled!` macro to allow callers to avoid
-    /// expensive computation of log message arguments if the message would be
-    /// discarded anyway.
-    fn enabled(&self, metadata: &Metadata) -> bool;
-
-    /// Logs the `Record`.
-    ///
-    /// Note that `enabled` is *not* necessarily called before this method.
-    /// Implementations of `log` should perform all necessary filtering
-    /// internally.
-    fn log(&self, record: &Record);
-
-    /// Flushes any buffered records.
-    fn flush(&self);
-}
-
-// Just used as a dummy initial value for LOGGER
-struct NopLogger;
-
-impl Log for NopLogger {
-    fn enabled(&self, _: &Metadata) -> bool {
-        false
-    }
-
-    fn log(&self, _: &Record) {}
-    fn flush(&self) {}
-}
-
-/// Sets the global maximum log level.
-///
-/// Generally, this should only be called by the active logging implementation.
-#[inline]
-pub fn set_max_level(level: LevelFilter) {
-    MAX_LOG_LEVEL_FILTER.store(level as usize, Ordering::SeqCst)
-}
-
-/// Returns the current maximum log level.
-///
-/// The [`log!`], [`error!`], [`warn!`], [`info!`], [`debug!`], and [`trace!`] macros check
-/// this value and discard any message logged at a higher level. The maximum
-/// log level is set by the [`set_max_level`] function.
-///
-/// [`log!`]: macro.log.html
-/// [`error!`]: macro.error.html
-/// [`warn!`]: macro.warn.html
-/// [`info!`]: macro.info.html
-/// [`debug!`]: macro.debug.html
-/// [`trace!`]: macro.trace.html
-/// [`set_max_level`]: fn.set_max_level.html
-#[inline(always)]
-pub fn max_level() -> LevelFilter {
-    unsafe { mem::transmute(MAX_LOG_LEVEL_FILTER.load(Ordering::Relaxed)) }
-}
-
-/// Sets the global logger to a `Box<Log>`.
-///
-/// This is a simple convenience wrapper over `set_logger`, which takes a
-/// `Box<Log>` rather than a `&'static Log`. See the documentation for
-/// [`set_logger`] for more details.
-///
-/// Requires the `std` feature.
-///
-/// # Errors
-///
-/// An error is returned if a logger has already been set.
-///
-/// [`set_logger`]: fn.set_logger.html
-#[cfg(all(feature = "std", atomic_cas))]
-pub fn set_boxed_logger(logger: Box<Log>) -> Result<(), SetLoggerError> {
-    set_logger_inner(|| unsafe { &*Box::into_raw(logger) })
-}
-
-/// Sets the global logger to a `&'static Log`.
-///
-/// This function may only be called once in the lifetime of a program. Any log
-/// events that occur before the call to `set_logger` completes will be ignored.
-///
-/// This function does not typically need to be called manually. Logger
-/// implementations should provide an initialization method that installs the
-/// logger internally.
-///
-/// # Availability
-///
-/// This method is available even when the `std` feature is disabled. However,
-/// it is currently unavailable on `thumbv6` targets, which lack support for
-/// some atomic operations which are used by this function. Even on those
-/// targets, [`set_logger_racy`] will be available.
-///
-/// # Errors
-///
-/// An error is returned if a logger has already been set.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::{error, info, warn, Record, Level, Metadata, LevelFilter};
-///
-/// static MY_LOGGER: MyLogger = MyLogger;
-///
-/// struct MyLogger;
-///
-/// impl log::Log for MyLogger {
-///     fn enabled(&self, metadata: &Metadata) -> bool {
-///         metadata.level() <= Level::Info
-///     }
-///
-///     fn log(&self, record: &Record) {
-///         if self.enabled(record.metadata()) {
-///             println!("{} - {}", record.level(), record.args());
-///         }
-///     }
-///     fn flush(&self) {}
-/// }
-///
-/// # fn main(){
-/// log::set_logger(&MY_LOGGER).unwrap();
-/// log::set_max_level(LevelFilter::Info);
-///
-/// info!("hello log");
-/// warn!("warning");
-/// error!("oops");
-/// # }
-/// ```
-///
-/// [`set_logger_racy`]: fn.set_logger_racy.html
-#[cfg(atomic_cas)]
-pub fn set_logger(logger: &'static Log) -> Result<(), SetLoggerError> {
-    set_logger_inner(|| logger)
-}
-
-#[cfg(atomic_cas)]
-fn set_logger_inner<F>(make_logger: F) -> Result<(), SetLoggerError>
-where
-    F: FnOnce() -> &'static Log,
-{
-    unsafe {
-        match STATE.compare_and_swap(UNINITIALIZED, INITIALIZING, Ordering::SeqCst) {
-            UNINITIALIZED => {
-                LOGGER = make_logger();
-                STATE.store(INITIALIZED, Ordering::SeqCst);
-                Ok(())
-            }
-            INITIALIZING => {
-                while STATE.load(Ordering::SeqCst) == INITIALIZING {}
-                Err(SetLoggerError(()))
-            }
-            _ => Err(SetLoggerError(())),
-        }
-    }
-}
-
-/// A thread-unsafe version of [`set_logger`].
-///
-/// This function is available on all platforms, even those that do not have
-/// support for atomics that is needed by [`set_logger`].
-///
-/// In almost all cases, [`set_logger`] should be preferred.
-///
-/// # Safety
-///
-/// This function is only safe to call when no other logger initialization
-/// function is called while this function still executes.
-///
-/// This can be upheld by (for example) making sure that **there are no other
-/// threads**, and (on embedded) that **interrupts are disabled**.
-///
-/// It is safe to use other logging functions while this function runs
-/// (including all logging macros).
-///
-/// [`set_logger`]: fn.set_logger.html
-pub unsafe fn set_logger_racy(logger: &'static Log) -> Result<(), SetLoggerError> {
-    match STATE.load(Ordering::SeqCst) {
-        UNINITIALIZED => {
-            LOGGER = logger;
-            STATE.store(INITIALIZED, Ordering::SeqCst);
-            Ok(())
-        }
-        INITIALIZING => {
-            // This is just plain UB, since we were racing another initialization function
-            unreachable!("set_logger_racy must not be used with other initialization functions")
-        }
-        _ => Err(SetLoggerError(())),
-    }
-}
-
-/// The type returned by [`set_logger`] if [`set_logger`] has already been called.
-///
-/// [`set_logger`]: fn.set_logger.html
-#[allow(missing_copy_implementations)]
-#[derive(Debug)]
-pub struct SetLoggerError(());
-
-impl fmt::Display for SetLoggerError {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        fmt.write_str(SET_LOGGER_ERROR)
-    }
-}
-
-// The Error trait is not available in libcore
-#[cfg(feature = "std")]
-impl error::Error for SetLoggerError {
-    fn description(&self) -> &str {
-        SET_LOGGER_ERROR
-    }
-}
-
-/// The type returned by [`from_str`] when the string doesn't match any of the log levels.
-///
-/// [`from_str`]: https://doc.rust-lang.org/std/str/trait.FromStr.html#tymethod.from_str
-#[allow(missing_copy_implementations)]
-#[derive(Debug, PartialEq)]
-pub struct ParseLevelError(());
-
-impl fmt::Display for ParseLevelError {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        fmt.write_str(LEVEL_PARSE_ERROR)
-    }
-}
-
-// The Error trait is not available in libcore
-#[cfg(feature = "std")]
-impl error::Error for ParseLevelError {
-    fn description(&self) -> &str {
-        LEVEL_PARSE_ERROR
-    }
-}
-
-/// Returns a reference to the logger.
-///
-/// If a logger has not been set, a no-op implementation is returned.
-pub fn logger() -> &'static Log {
-    unsafe {
-        if STATE.load(Ordering::SeqCst) != INITIALIZED {
-            static NOP: NopLogger = NopLogger;
-            &NOP
-        } else {
-            LOGGER
-        }
-    }
-}
-
-// WARNING: this is not part of the crate's public API and is subject to change at any time
-#[doc(hidden)]
-pub fn __private_api_log(
-    args: fmt::Arguments,
-    level: Level,
-    &(target, module_path, file, line): &(&str, &'static str, &'static str, u32),
-) {
-    logger().log(
-        &Record::builder()
-            .args(args)
-            .level(level)
-            .target(target)
-            .module_path_static(Some(module_path))
-            .file_static(Some(file))
-            .line(Some(line))
-            .build(),
-    );
-}
-
-// WARNING: this is not part of the crate's public API and is subject to change at any time
-#[doc(hidden)]
-pub fn __private_api_enabled(level: Level, target: &str) -> bool {
-    logger().enabled(&Metadata::builder().level(level).target(target).build())
-}
-
-/// The statically resolved maximum log level.
-///
-/// See the crate level documentation for information on how to configure this.
-///
-/// This value is checked by the log macros, but not by the `Log`ger returned by
-/// the [`logger`] function. Code that manually calls functions on that value
-/// should compare the level against this value.
-///
-/// [`logger`]: fn.logger.html
-pub const STATIC_MAX_LEVEL: LevelFilter = MAX_LEVEL_INNER;
-
-cfg_if! {
-    if #[cfg(all(not(debug_assertions), feature = "release_max_level_off"))] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Off;
-    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_error"))] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Error;
-    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_warn"))] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Warn;
-    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_info"))] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Info;
-    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_debug"))] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Debug;
-    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_trace"))] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Trace;
-    } else if #[cfg(feature = "max_level_off")] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Off;
-    } else if #[cfg(feature = "max_level_error")] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Error;
-    } else if #[cfg(feature = "max_level_warn")] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Warn;
-    } else if #[cfg(feature = "max_level_info")] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Info;
-    } else if #[cfg(feature = "max_level_debug")] {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Debug;
-    } else {
-        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Trace;
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    extern crate std;
-    use super::{Level, LevelFilter, ParseLevelError};
-    use tests::std::string::ToString;
-
-    #[test]
-    fn test_levelfilter_from_str() {
-        let tests = [
-            ("off", Ok(LevelFilter::Off)),
-            ("error", Ok(LevelFilter::Error)),
-            ("warn", Ok(LevelFilter::Warn)),
-            ("info", Ok(LevelFilter::Info)),
-            ("debug", Ok(LevelFilter::Debug)),
-            ("trace", Ok(LevelFilter::Trace)),
-            ("OFF", Ok(LevelFilter::Off)),
-            ("ERROR", Ok(LevelFilter::Error)),
-            ("WARN", Ok(LevelFilter::Warn)),
-            ("INFO", Ok(LevelFilter::Info)),
-            ("DEBUG", Ok(LevelFilter::Debug)),
-            ("TRACE", Ok(LevelFilter::Trace)),
-            ("asdf", Err(ParseLevelError(()))),
-        ];
-        for &(s, ref expected) in &tests {
-            assert_eq!(expected, &s.parse());
-        }
-    }
-
-    #[test]
-    fn test_level_from_str() {
-        let tests = [
-            ("OFF", Err(ParseLevelError(()))),
-            ("error", Ok(Level::Error)),
-            ("warn", Ok(Level::Warn)),
-            ("info", Ok(Level::Info)),
-            ("debug", Ok(Level::Debug)),
-            ("trace", Ok(Level::Trace)),
-            ("ERROR", Ok(Level::Error)),
-            ("WARN", Ok(Level::Warn)),
-            ("INFO", Ok(Level::Info)),
-            ("DEBUG", Ok(Level::Debug)),
-            ("TRACE", Ok(Level::Trace)),
-            ("asdf", Err(ParseLevelError(()))),
-        ];
-        for &(s, ref expected) in &tests {
-            assert_eq!(expected, &s.parse());
-        }
-    }
-
-    #[test]
-    fn test_level_show() {
-        assert_eq!("INFO", Level::Info.to_string());
-        assert_eq!("ERROR", Level::Error.to_string());
-    }
-
-    #[test]
-    fn test_levelfilter_show() {
-        assert_eq!("OFF", LevelFilter::Off.to_string());
-        assert_eq!("ERROR", LevelFilter::Error.to_string());
-    }
-
-    #[test]
-    fn test_cross_cmp() {
-        assert!(Level::Debug > LevelFilter::Error);
-        assert!(LevelFilter::Warn < Level::Trace);
-        assert!(LevelFilter::Off < Level::Error);
-    }
-
-    #[test]
-    fn test_cross_eq() {
-        assert!(Level::Error == LevelFilter::Error);
-        assert!(LevelFilter::Off != Level::Error);
-        assert!(Level::Trace == LevelFilter::Trace);
-    }
-
-    #[test]
-    fn test_to_level() {
-        assert_eq!(Some(Level::Error), LevelFilter::Error.to_level());
-        assert_eq!(None, LevelFilter::Off.to_level());
-        assert_eq!(Some(Level::Debug), LevelFilter::Debug.to_level());
-    }
-
-    #[test]
-    fn test_to_level_filter() {
-        assert_eq!(LevelFilter::Error, Level::Error.to_level_filter());
-        assert_eq!(LevelFilter::Trace, Level::Trace.to_level_filter());
-    }
-
-    #[test]
-    #[cfg(feature = "std")]
-    fn test_error_trait() {
-        use super::SetLoggerError;
-        use std::error::Error;
-        let e = SetLoggerError(());
-        assert_eq!(
-            e.description(),
-            "attempted to set a logger after the logging system \
-             was already initialized"
-        );
-    }
-
-    #[test]
-    fn test_metadata_builder() {
-        use super::MetadataBuilder;
-        let target = "myApp";
-        let metadata_test = MetadataBuilder::new()
-            .level(Level::Debug)
-            .target(target)
-            .build();
-        assert_eq!(metadata_test.level(), Level::Debug);
-        assert_eq!(metadata_test.target(), "myApp");
-    }
-
-    #[test]
-    fn test_metadata_convenience_builder() {
-        use super::Metadata;
-        let target = "myApp";
-        let metadata_test = Metadata::builder()
-            .level(Level::Debug)
-            .target(target)
-            .build();
-        assert_eq!(metadata_test.level(), Level::Debug);
-        assert_eq!(metadata_test.target(), "myApp");
-    }
-
-    #[test]
-    fn test_record_builder() {
-        use super::{MetadataBuilder, RecordBuilder};
-        let target = "myApp";
-        let metadata = MetadataBuilder::new().target(target).build();
-        let fmt_args = format_args!("hello");
-        let record_test = RecordBuilder::new()
-            .args(fmt_args)
-            .metadata(metadata)
-            .module_path(Some("foo"))
-            .file(Some("bar"))
-            .line(Some(30))
-            .build();
-        assert_eq!(record_test.metadata().target(), "myApp");
-        assert_eq!(record_test.module_path(), Some("foo"));
-        assert_eq!(record_test.file(), Some("bar"));
-        assert_eq!(record_test.line(), Some(30));
-    }
-
-    #[test]
-    fn test_record_convenience_builder() {
-        use super::{Metadata, Record};
-        let target = "myApp";
-        let metadata = Metadata::builder().target(target).build();
-        let fmt_args = format_args!("hello");
-        let record_test = Record::builder()
-            .args(fmt_args)
-            .metadata(metadata)
-            .module_path(Some("foo"))
-            .file(Some("bar"))
-            .line(Some(30))
-            .build();
-        assert_eq!(record_test.target(), "myApp");
-        assert_eq!(record_test.module_path(), Some("foo"));
-        assert_eq!(record_test.file(), Some("bar"));
-        assert_eq!(record_test.line(), Some(30));
-    }
-
-    #[test]
-    fn test_record_complete_builder() {
-        use super::{Level, Record};
-        let target = "myApp";
-        let record_test = Record::builder()
-            .module_path(Some("foo"))
-            .file(Some("bar"))
-            .line(Some(30))
-            .target(target)
-            .level(Level::Error)
-            .build();
-        assert_eq!(record_test.target(), "myApp");
-        assert_eq!(record_test.level(), Level::Error);
-        assert_eq!(record_test.module_path(), Some("foo"));
-        assert_eq!(record_test.file(), Some("bar"));
-        assert_eq!(record_test.line(), Some(30));
-    }
-
-    #[test]
-    #[cfg(feature = "kv_unstable")]
-    fn test_record_key_values_builder() {
-        use super::Record;
-        use kv::{self, Visitor};
-
-        struct TestVisitor {
-            seen_pairs: usize,
-        }
-
-        impl<'kvs> Visitor<'kvs> for TestVisitor {
-            fn visit_pair(
-                &mut self,
-                _: kv::Key<'kvs>,
-                _: kv::Value<'kvs>
-            ) -> Result<(), kv::Error> {
-                self.seen_pairs += 1;
-                Ok(())
-            }
-        }
-
-        let kvs: &[(&str, i32)] = &[
-            ("a", 1),
-            ("b", 2)
-        ];
-        let record_test = Record::builder()
-            .key_values(&kvs)
-            .build();
-
-        let mut visitor = TestVisitor {
-            seen_pairs: 0,
-        };
-
-        record_test.key_values().visit(&mut visitor).unwrap();
-
-        assert_eq!(2, visitor.seen_pairs);
-    }
-}
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT

+// file at the top-level directory of this distribution and at

+// http://rust-lang.org/COPYRIGHT.

+//

+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or

+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license

+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your

+// option. This file may not be copied, modified, or distributed

+// except according to those terms.

+

+//! A lightweight logging facade.

+//!

+//! The `log` crate provides a single logging API that abstracts over the

+//! actual logging implementation. Libraries can use the logging API provided

+//! by this crate, and the consumer of those libraries can choose the logging

+//! implementation that is most suitable for its use case.

+//!

+//! If no logging implementation is selected, the facade falls back to a "noop"

+//! implementation that ignores all log messages. The overhead in this case

+//! is very small - just an integer load, comparison and jump.

+//!

+//! A log request consists of a _target_, a _level_, and a _body_. A target is a

+//! string which defaults to the module path of the location of the log request,

+//! though that default may be overridden. Logger implementations typically use

+//! the target to filter requests based on some user configuration.

+//!

+//! # Use

+//!

+//! The basic use of the log crate is through the five logging macros: [`error!`],

+//! [`warn!`], [`info!`], [`debug!`] and [`trace!`]

+//! where `error!` represents the highest-priority log messages

+//! and `trace!` the lowest. The log messages are filtered by configuring

+//! the log level to exclude messages with a lower priority.

+//! Each of these macros accept format strings similarly to [`println!`].

+//!

+//!

+//! [`error!`]: ./macro.error.html

+//! [`warn!`]: ./macro.warn.html

+//! [`info!`]: ./macro.info.html

+//! [`debug!`]: ./macro.debug.html

+//! [`trace!`]: ./macro.trace.html

+//! [`println!`]: https://doc.rust-lang.org/stable/std/macro.println.html

+//!

+//! ## In libraries

+//!

+//! Libraries should link only to the `log` crate, and use the provided

+//! macros to log whatever information will be useful to downstream consumers.

+//!

+//! ### Examples

+//!

+//! ```edition2018

+//! # #[derive(Debug)] pub struct Yak(String);

+//! # impl Yak { fn shave(&mut self, _: u32) {} }

+//! # fn find_a_razor() -> Result<u32, u32> { Ok(1) }

+//! use log::{info, warn};

+//!

+//! pub fn shave_the_yak(yak: &mut Yak) {

+//!     info!(target: "yak_events", "Commencing yak shaving for {:?}", yak);

+//!

+//!     loop {

+//!         match find_a_razor() {

+//!             Ok(razor) => {

+//!                 info!("Razor located: {}", razor);

+//!                 yak.shave(razor);

+//!                 break;

+//!             }

+//!             Err(err) => {

+//!                 warn!("Unable to locate a razor: {}, retrying", err);

+//!             }

+//!         }

+//!     }

+//! }

+//! # fn main() {}

+//! ```

+//!

+//! ## In executables

+//!

+//! Executables should choose a logging implementation and initialize it early in the

+//! runtime of the program. Logging implementations will typically include a

+//! function to do this. Any log messages generated before

+//! the implementation is initialized will be ignored.

+//!

+//! The executable itself may use the `log` crate to log as well.

+//!

+//! ### Warning

+//!

+//! The logging system may only be initialized once.

+//!

+//! # Available logging implementations

+//!

+//! In order to produce log output executables have to use

+//! a logger implementation compatible with the facade.

+//! There are many available implementations to choose from,

+//! here are some of the most popular ones:

+//!

+//! * Simple minimal loggers:

+//!     * [env_logger]

+//!     * [simple_logger]

+//!     * [simplelog]

+//!     * [pretty_env_logger]

+//!     * [stderrlog]

+//!     * [flexi_logger]

+//! * Complex configurable frameworks:

+//!     * [log4rs]

+//!     * [fern]

+//! * Adaptors for other facilities:

+//!     * [syslog]

+//!     * [slog-stdlog]

+//!

+//! # Implementing a Logger

+//!

+//! Loggers implement the [`Log`] trait. Here's a very basic example that simply

+//! logs all messages at the [`Error`][level_link], [`Warn`][level_link] or

+//! [`Info`][level_link] levels to stdout:

+//!

+//! ```edition2018

+//! use log::{Record, Level, Metadata};

+//!

+//! struct SimpleLogger;

+//!

+//! impl log::Log for SimpleLogger {

+//!     fn enabled(&self, metadata: &Metadata) -> bool {

+//!         metadata.level() <= Level::Info

+//!     }

+//!

+//!     fn log(&self, record: &Record) {

+//!         if self.enabled(record.metadata()) {

+//!             println!("{} - {}", record.level(), record.args());

+//!         }

+//!     }

+//!

+//!     fn flush(&self) {}

+//! }

+//!

+//! # fn main() {}

+//! ```

+//!

+//! Loggers are installed by calling the [`set_logger`] function. The maximum

+//! log level also needs to be adjusted via the [`set_max_level`] function. The

+//! logging facade uses this as an optimization to improve performance of log

+//! messages at levels that are disabled. It's important to set it, as it

+//! defaults to [`Off`][filter_link], so no log messages will ever be captured!

+//! In the case of our example logger, we'll want to set the maximum log level

+//! to [`Info`][filter_link], since we ignore any [`Debug`][level_link] or

+//! [`Trace`][level_link] level log messages. A logging implementation should

+//! provide a function that wraps a call to [`set_logger`] and

+//! [`set_max_level`], handling initialization of the logger:

+//!

+//! ```edition2018

+//! # use log::{Level, Metadata};

+//! # struct SimpleLogger;

+//! # impl log::Log for SimpleLogger {

+//! #   fn enabled(&self, _: &Metadata) -> bool { false }

+//! #   fn log(&self, _: &log::Record) {}

+//! #   fn flush(&self) {}

+//! # }

+//! # fn main() {}

+//! use log::{SetLoggerError, LevelFilter};

+//!

+//! static LOGGER: SimpleLogger = SimpleLogger;

+//!

+//! pub fn init() -> Result<(), SetLoggerError> {

+//!     log::set_logger(&LOGGER)

+//!         .map(|()| log::set_max_level(LevelFilter::Info))

+//! }

+//! ```

+//!

+//! Implementations that adjust their configurations at runtime should take care

+//! to adjust the maximum log level as well.

+//!

+//! # Use with `std`

+//!

+//! `set_logger` requires you to provide a `&'static Log`, which can be hard to

+//! obtain if your logger depends on some runtime configuration. The

+//! `set_boxed_logger` function is available with the `std` Cargo feature. It is

+//! identical to `set_logger` except that it takes a `Box<Log>` rather than a

+//! `&'static Log`:

+//!

+//! ```edition2018

+//! # use log::{Level, LevelFilter, Log, SetLoggerError, Metadata};

+//! # struct SimpleLogger;

+//! # impl log::Log for SimpleLogger {

+//! #   fn enabled(&self, _: &Metadata) -> bool { false }

+//! #   fn log(&self, _: &log::Record) {}

+//! #   fn flush(&self) {}

+//! # }

+//! # fn main() {}

+//! # #[cfg(feature = "std")]

+//! pub fn init() -> Result<(), SetLoggerError> {

+//!     log::set_boxed_logger(Box::new(SimpleLogger))

+//!         .map(|()| log::set_max_level(LevelFilter::Info))

+//! }

+//! ```

+//!

+//! # Compile time filters

+//!

+//! Log levels can be statically disabled at compile time via Cargo features. Log invocations at

+//! disabled levels will be skipped and will not even be present in the resulting binary.

+//! This level is configured separately for release and debug builds. The features are:

+//!

+//! * `max_level_off`

+//! * `max_level_error`

+//! * `max_level_warn`

+//! * `max_level_info`

+//! * `max_level_debug`

+//! * `max_level_trace`

+//! * `release_max_level_off`

+//! * `release_max_level_error`

+//! * `release_max_level_warn`

+//! * `release_max_level_info`

+//! * `release_max_level_debug`

+//! * `release_max_level_trace`

+//!

+//! These features control the value of the `STATIC_MAX_LEVEL` constant. The logging macros check

+//! this value before logging a message. By default, no levels are disabled.

+//!

+//! Libraries should avoid using the max level features because they're global and can't be changed

+//! once they're set.

+//!

+//! For example, a crate can disable trace level logs in debug builds and trace, debug, and info

+//! level logs in release builds with the following configuration:

+//!

+//! ```toml

+//! [dependencies]

+//! log = { version = "0.4", features = ["max_level_debug", "release_max_level_warn"] }

+//! ```

+//! # Crate Feature Flags

+//!

+//! The following crate feature flags are available in addition to the filters. They are

+//! configured in your `Cargo.toml`.

+//!

+//! * `std` allows use of `std` crate instead of the default `core`. Enables using `std::error` and

+//! `set_boxed_logger` functionality.

+//! * `serde` enables support for serialization and deserialization of `Level` and `LevelFilter`.

+//!

+//! ```toml

+//! [dependencies]

+//! log = { version = "0.4", features = ["std", "serde"] }

+//! ```

+//!

+//! # Version compatibility

+//!

+//! The 0.3 and 0.4 versions of the `log` crate are almost entirely compatible. Log messages

+//! made using `log` 0.3 will forward transparently to a logger implementation using `log` 0.4. Log

+//! messages made using `log` 0.4 will forward to a logger implementation using `log` 0.3, but the

+//! module path and file name information associated with the message will unfortunately be lost.

+//!

+//! [`Log`]: trait.Log.html

+//! [level_link]: enum.Level.html

+//! [filter_link]: enum.LevelFilter.html

+//! [`set_logger`]: fn.set_logger.html

+//! [`set_max_level`]: fn.set_max_level.html

+//! [`try_set_logger_raw`]: fn.try_set_logger_raw.html

+//! [`shutdown_logger_raw`]: fn.shutdown_logger_raw.html

+//! [env_logger]: https://docs.rs/env_logger/*/env_logger/

+//! [simple_logger]: https://github.com/borntyping/rust-simple_logger

+//! [simplelog]: https://github.com/drakulix/simplelog.rs

+//! [pretty_env_logger]: https://docs.rs/pretty_env_logger/*/pretty_env_logger/

+//! [stderrlog]: https://docs.rs/stderrlog/*/stderrlog/

+//! [flexi_logger]: https://docs.rs/flexi_logger/*/flexi_logger/

+//! [syslog]: https://docs.rs/syslog/*/syslog/

+//! [slog-stdlog]: https://docs.rs/slog-stdlog/*/slog_stdlog/

+//! [log4rs]: https://docs.rs/log4rs/*/log4rs/

+//! [fern]: https://docs.rs/fern/*/fern/

+

+#![doc(

+    html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png",

+    html_favicon_url = "https://www.rust-lang.org/favicon.ico",

+    html_root_url = "https://docs.rs/log/0.4.11"

+)]

+#![warn(missing_docs)]

+#![deny(missing_debug_implementations)]

+#![cfg_attr(all(not(feature = "std"), not(test)), no_std)]

+// When compiled for the rustc compiler itself we want to make sure that this is

+// an unstable crate

+#![cfg_attr(rustbuild, feature(staged_api, rustc_private))]

+#![cfg_attr(rustbuild, unstable(feature = "rustc_private", issue = "27812"))]

+

+#[cfg(all(not(feature = "std"), not(test)))]

+extern crate core as std;

+

+#[macro_use]

+extern crate cfg_if;

+

+use std::cmp;

+#[cfg(feature = "std")]

+use std::error;

+use std::fmt;

+use std::mem;

+use std::str::FromStr;

+use std::sync::atomic::{AtomicUsize, Ordering};

+

+#[macro_use]

+mod macros;

+mod serde;

+

+#[cfg(feature = "kv_unstable")]

+pub mod kv;

+

+// The LOGGER static holds a pointer to the global logger. It is protected by

+// the STATE static which determines whether LOGGER has been initialized yet.

+static mut LOGGER: &dyn Log = &NopLogger;

+

+static STATE: AtomicUsize = AtomicUsize::new(0);

+

+// There are three different states that we care about: the logger's

+// uninitialized, the logger's initializing (set_logger's been called but

+// LOGGER hasn't actually been set yet), or the logger's active.

+const UNINITIALIZED: usize = 0;

+const INITIALIZING: usize = 1;

+const INITIALIZED: usize = 2;

+

+static MAX_LOG_LEVEL_FILTER: AtomicUsize = AtomicUsize::new(0);

+

+static LOG_LEVEL_NAMES: [&str; 6] = ["OFF", "ERROR", "WARN", "INFO", "DEBUG", "TRACE"];

+

+static SET_LOGGER_ERROR: &str = "attempted to set a logger after the logging system \

+                                 was already initialized";

+static LEVEL_PARSE_ERROR: &str =

+    "attempted to convert a string that doesn't match an existing log level";

+

+/// An enum representing the available verbosity levels of the logger.

+///

+/// Typical usage includes: checking if a certain `Level` is enabled with

+/// [`log_enabled!`](macro.log_enabled.html), specifying the `Level` of

+/// [`log!`](macro.log.html), and comparing a `Level` directly to a

+/// [`LevelFilter`](enum.LevelFilter.html).

+#[repr(usize)]

+#[derive(Copy, Eq, Debug, Hash)]

+pub enum Level {

+    /// The "error" level.

+    ///

+    /// Designates very serious errors.

+    // This way these line up with the discriminants for LevelFilter below

+    // This works because Rust treats field-less enums the same way as C does:

+    // https://doc.rust-lang.org/reference/items/enumerations.html#custom-discriminant-values-for-field-less-enumerations

+    Error = 1,

+    /// The "warn" level.

+    ///

+    /// Designates hazardous situations.

+    Warn,

+    /// The "info" level.

+    ///

+    /// Designates useful information.

+    Info,

+    /// The "debug" level.

+    ///

+    /// Designates lower priority information.

+    Debug,

+    /// The "trace" level.

+    ///

+    /// Designates very low priority, often extremely verbose, information.

+    Trace,

+}

+

+impl Clone for Level {

+    #[inline]

+    fn clone(&self) -> Level {

+        *self

+    }

+}

+

+impl PartialEq for Level {

+    #[inline]

+    fn eq(&self, other: &Level) -> bool {

+        *self as usize == *other as usize

+    }

+}

+

+impl PartialEq<LevelFilter> for Level {

+    #[inline]

+    fn eq(&self, other: &LevelFilter) -> bool {

+        *self as usize == *other as usize

+    }

+}

+

+impl PartialOrd for Level {

+    #[inline]

+    fn partial_cmp(&self, other: &Level) -> Option<cmp::Ordering> {

+        Some(self.cmp(other))

+    }

+

+    #[inline]

+    fn lt(&self, other: &Level) -> bool {

+        (*self as usize) < *other as usize

+    }

+

+    #[inline]

+    fn le(&self, other: &Level) -> bool {

+        *self as usize <= *other as usize

+    }

+

+    #[inline]

+    fn gt(&self, other: &Level) -> bool {

+        *self as usize > *other as usize

+    }

+

+    #[inline]

+    fn ge(&self, other: &Level) -> bool {

+        *self as usize >= *other as usize

+    }

+}

+

+impl PartialOrd<LevelFilter> for Level {

+    #[inline]

+    fn partial_cmp(&self, other: &LevelFilter) -> Option<cmp::Ordering> {

+        Some((*self as usize).cmp(&(*other as usize)))

+    }

+

+    #[inline]

+    fn lt(&self, other: &LevelFilter) -> bool {

+        (*self as usize) < *other as usize

+    }

+

+    #[inline]

+    fn le(&self, other: &LevelFilter) -> bool {

+        *self as usize <= *other as usize

+    }

+

+    #[inline]

+    fn gt(&self, other: &LevelFilter) -> bool {

+        *self as usize > *other as usize

+    }

+

+    #[inline]

+    fn ge(&self, other: &LevelFilter) -> bool {

+        *self as usize >= *other as usize

+    }

+}

+

+impl Ord for Level {

+    #[inline]

+    fn cmp(&self, other: &Level) -> cmp::Ordering {

+        (*self as usize).cmp(&(*other as usize))

+    }

+}

+

+fn ok_or<T, E>(t: Option<T>, e: E) -> Result<T, E> {

+    match t {

+        Some(t) => Ok(t),

+        None => Err(e),

+    }

+}

+

+// Reimplemented here because std::ascii is not available in libcore

+fn eq_ignore_ascii_case(a: &str, b: &str) -> bool {

+    fn to_ascii_uppercase(c: u8) -> u8 {

+        if c >= b'a' && c <= b'z' {

+            c - b'a' + b'A'

+        } else {

+            c

+        }

+    }

+

+    if a.len() == b.len() {

+        a.bytes()

+            .zip(b.bytes())

+            .all(|(a, b)| to_ascii_uppercase(a) == to_ascii_uppercase(b))

+    } else {

+        false

+    }

+}

+

+impl FromStr for Level {

+    type Err = ParseLevelError;

+    fn from_str(level: &str) -> Result<Level, Self::Err> {

+        ok_or(

+            LOG_LEVEL_NAMES

+                .iter()

+                .position(|&name| eq_ignore_ascii_case(name, level))

+                .into_iter()

+                .filter(|&idx| idx != 0)

+                .map(|idx| Level::from_usize(idx).unwrap())

+                .next(),

+            ParseLevelError(()),

+        )

+    }

+}

+

+impl fmt::Display for Level {

+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {

+        fmt.pad(LOG_LEVEL_NAMES[*self as usize])

+    }

+}

+

+impl Level {

+    fn from_usize(u: usize) -> Option<Level> {

+        match u {

+            1 => Some(Level::Error),

+            2 => Some(Level::Warn),

+            3 => Some(Level::Info),

+            4 => Some(Level::Debug),

+            5 => Some(Level::Trace),

+            _ => None,

+        }

+    }

+

+    /// Returns the most verbose logging level.

+    #[inline]

+    pub fn max() -> Level {

+        Level::Trace

+    }

+

+    /// Converts the `Level` to the equivalent `LevelFilter`.

+    #[inline]

+    pub fn to_level_filter(&self) -> LevelFilter {

+        LevelFilter::from_usize(*self as usize).unwrap()

+    }

+}

+

+/// An enum representing the available verbosity level filters of the logger.

+///

+/// A `LevelFilter` may be compared directly to a [`Level`]. Use this type

+/// to get and set the maximum log level with [`max_level()`] and [`set_max_level`].

+///

+/// [`Level`]: enum.Level.html

+/// [`max_level()`]: fn.max_level.html

+/// [`set_max_level`]: fn.set_max_level.html

+#[repr(usize)]

+#[derive(Copy, Eq, Debug, Hash)]

+pub enum LevelFilter {

+    /// A level lower than all log levels.

+    Off,

+    /// Corresponds to the `Error` log level.

+    Error,

+    /// Corresponds to the `Warn` log level.

+    Warn,

+    /// Corresponds to the `Info` log level.

+    Info,

+    /// Corresponds to the `Debug` log level.

+    Debug,

+    /// Corresponds to the `Trace` log level.

+    Trace,

+}

+

+// Deriving generates terrible impls of these traits

+

+impl Clone for LevelFilter {

+    #[inline]

+    fn clone(&self) -> LevelFilter {

+        *self

+    }

+}

+

+impl PartialEq for LevelFilter {

+    #[inline]

+    fn eq(&self, other: &LevelFilter) -> bool {

+        *self as usize == *other as usize

+    }

+}

+

+impl PartialEq<Level> for LevelFilter {

+    #[inline]

+    fn eq(&self, other: &Level) -> bool {

+        other.eq(self)

+    }

+}

+

+impl PartialOrd for LevelFilter {

+    #[inline]

+    fn partial_cmp(&self, other: &LevelFilter) -> Option<cmp::Ordering> {

+        Some(self.cmp(other))

+    }

+

+    #[inline]

+    fn lt(&self, other: &LevelFilter) -> bool {

+        (*self as usize) < *other as usize

+    }

+

+    #[inline]

+    fn le(&self, other: &LevelFilter) -> bool {

+        *self as usize <= *other as usize

+    }

+

+    #[inline]

+    fn gt(&self, other: &LevelFilter) -> bool {

+        *self as usize > *other as usize

+    }

+

+    #[inline]

+    fn ge(&self, other: &LevelFilter) -> bool {

+        *self as usize >= *other as usize

+    }

+}

+

+impl PartialOrd<Level> for LevelFilter {

+    #[inline]

+    fn partial_cmp(&self, other: &Level) -> Option<cmp::Ordering> {

+        Some((*self as usize).cmp(&(*other as usize)))

+    }

+

+    #[inline]

+    fn lt(&self, other: &Level) -> bool {

+        (*self as usize) < *other as usize

+    }

+

+    #[inline]

+    fn le(&self, other: &Level) -> bool {

+        *self as usize <= *other as usize

+    }

+

+    #[inline]

+    fn gt(&self, other: &Level) -> bool {

+        *self as usize > *other as usize

+    }

+

+    #[inline]

+    fn ge(&self, other: &Level) -> bool {

+        *self as usize >= *other as usize

+    }

+}

+

+impl Ord for LevelFilter {

+    #[inline]

+    fn cmp(&self, other: &LevelFilter) -> cmp::Ordering {

+        (*self as usize).cmp(&(*other as usize))

+    }

+}

+

+impl FromStr for LevelFilter {

+    type Err = ParseLevelError;

+    fn from_str(level: &str) -> Result<LevelFilter, Self::Err> {

+        ok_or(

+            LOG_LEVEL_NAMES

+                .iter()

+                .position(|&name| eq_ignore_ascii_case(name, level))

+                .map(|p| LevelFilter::from_usize(p).unwrap()),

+            ParseLevelError(()),

+        )

+    }

+}

+

+impl fmt::Display for LevelFilter {

+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {

+        fmt.pad(LOG_LEVEL_NAMES[*self as usize])

+    }

+}

+

+impl LevelFilter {

+    fn from_usize(u: usize) -> Option<LevelFilter> {

+        match u {

+            0 => Some(LevelFilter::Off),

+            1 => Some(LevelFilter::Error),

+            2 => Some(LevelFilter::Warn),

+            3 => Some(LevelFilter::Info),

+            4 => Some(LevelFilter::Debug),

+            5 => Some(LevelFilter::Trace),

+            _ => None,

+        }

+    }

+    /// Returns the most verbose logging level filter.

+    #[inline]

+    pub fn max() -> LevelFilter {

+        LevelFilter::Trace

+    }

+

+    /// Converts `self` to the equivalent `Level`.

+    ///

+    /// Returns `None` if `self` is `LevelFilter::Off`.

+    #[inline]

+    pub fn to_level(&self) -> Option<Level> {

+        Level::from_usize(*self as usize)

+    }

+}

+

+#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]

+enum MaybeStaticStr<'a> {

+    Static(&'static str),

+    Borrowed(&'a str),

+}

+

+impl<'a> MaybeStaticStr<'a> {

+    #[inline]

+    fn get(&self) -> &'a str {

+        match *self {

+            MaybeStaticStr::Static(s) => s,

+            MaybeStaticStr::Borrowed(s) => s,

+        }

+    }

+}

+

+/// The "payload" of a log message.

+///

+/// # Use

+///

+/// `Record` structures are passed as parameters to the [`log`][method.log]

+/// method of the [`Log`] trait. Logger implementors manipulate these

+/// structures in order to display log messages. `Record`s are automatically

+/// created by the [`log!`] macro and so are not seen by log users.

+///

+/// Note that the [`level()`] and [`target()`] accessors are equivalent to

+/// `self.metadata().level()` and `self.metadata().target()` respectively.

+/// These methods are provided as a convenience for users of this structure.

+///

+/// # Example

+///

+/// The following example shows a simple logger that displays the level,

+/// module path, and message of any `Record` that is passed to it.

+///

+/// ```edition2018

+/// struct SimpleLogger;

+///

+/// impl log::Log for SimpleLogger {

+///    fn enabled(&self, metadata: &log::Metadata) -> bool {

+///        true

+///    }

+///

+///    fn log(&self, record: &log::Record) {

+///        if !self.enabled(record.metadata()) {

+///            return;

+///        }

+///

+///        println!("{}:{} -- {}",

+///                 record.level(),

+///                 record.target(),

+///                 record.args());

+///    }

+///    fn flush(&self) {}

+/// }

+/// ```

+///

+/// [method.log]: trait.Log.html#tymethod.log

+/// [`Log`]: trait.Log.html

+/// [`log!`]: macro.log.html

+/// [`level()`]: struct.Record.html#method.level

+/// [`target()`]: struct.Record.html#method.target

+#[derive(Clone, Debug)]

+pub struct Record<'a> {

+    metadata: Metadata<'a>,

+    args: fmt::Arguments<'a>,

+    module_path: Option<MaybeStaticStr<'a>>,

+    file: Option<MaybeStaticStr<'a>>,

+    line: Option<u32>,

+    #[cfg(feature = "kv_unstable")]

+    key_values: KeyValues<'a>,

+}

+

+// This wrapper type is only needed so we can

+// `#[derive(Debug)]` on `Record`. It also

+// provides a useful `Debug` implementation for

+// the underlying `Source`.

+#[cfg(feature = "kv_unstable")]

+#[derive(Clone)]

+struct KeyValues<'a>(&'a dyn kv::Source);

+

+#[cfg(feature = "kv_unstable")]

+impl<'a> fmt::Debug for KeyValues<'a> {

+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {

+        let mut visitor = f.debug_map();

+        self.0.visit(&mut visitor).map_err(|_| fmt::Error)?;

+        visitor.finish()

+    }

+}

+

+impl<'a> Record<'a> {

+    /// Returns a new builder.

+    #[inline]

+    pub fn builder() -> RecordBuilder<'a> {

+        RecordBuilder::new()

+    }

+

+    /// The message body.

+    #[inline]

+    pub fn args(&self) -> &fmt::Arguments<'a> {

+        &self.args

+    }

+

+    /// Metadata about the log directive.

+    #[inline]

+    pub fn metadata(&self) -> &Metadata<'a> {

+        &self.metadata

+    }

+

+    /// The verbosity level of the message.

+    #[inline]

+    pub fn level(&self) -> Level {

+        self.metadata.level()

+    }

+

+    /// The name of the target of the directive.

+    #[inline]

+    pub fn target(&self) -> &'a str {

+        self.metadata.target()

+    }

+

+    /// The module path of the message.

+    #[inline]

+    pub fn module_path(&self) -> Option<&'a str> {

+        self.module_path.map(|s| s.get())

+    }

+

+    /// The module path of the message, if it is a `'static` string.

+    #[inline]

+    pub fn module_path_static(&self) -> Option<&'static str> {

+        match self.module_path {

+            Some(MaybeStaticStr::Static(s)) => Some(s),

+            _ => None,

+        }

+    }

+

+    /// The source file containing the message.

+    #[inline]

+    pub fn file(&self) -> Option<&'a str> {

+        self.file.map(|s| s.get())

+    }

+

+    /// The module path of the message, if it is a `'static` string.

+    #[inline]

+    pub fn file_static(&self) -> Option<&'static str> {

+        match self.file {

+            Some(MaybeStaticStr::Static(s)) => Some(s),

+            _ => None,

+        }

+    }

+

+    /// The line containing the message.

+    #[inline]

+    pub fn line(&self) -> Option<u32> {

+        self.line

+    }

+

+    /// The structued key-value pairs associated with the message.

+    #[cfg(feature = "kv_unstable")]

+    #[inline]

+    pub fn key_values(&self) -> &dyn kv::Source {

+        self.key_values.0

+    }

+

+    /// Create a new [`RecordBuilder`](struct.RecordBuilder.html) based on this record.

+    #[cfg(feature = "kv_unstable")]

+    #[inline]

+    pub fn to_builder(&self) -> RecordBuilder {

+        RecordBuilder {

+            record: Record {

+                metadata: Metadata {

+                    level: self.metadata.level,

+                    target: self.metadata.target,

+                },

+                args: self.args,

+                module_path: self.module_path,

+                file: self.file,

+                line: self.line,

+                key_values: self.key_values.clone(),

+            },

+        }

+    }

+}

+

+/// Builder for [`Record`](struct.Record.html).

+///

+/// Typically should only be used by log library creators or for testing and "shim loggers".

+/// The `RecordBuilder` can set the different parameters of `Record` object, and returns

+/// the created object when `build` is called.

+///

+/// # Examples

+///

+///

+/// ```edition2018

+/// use log::{Level, Record};

+///

+/// let record = Record::builder()

+///                 .args(format_args!("Error!"))

+///                 .level(Level::Error)

+///                 .target("myApp")

+///                 .file(Some("server.rs"))

+///                 .line(Some(144))

+///                 .module_path(Some("server"))

+///                 .build();

+/// ```

+///

+/// Alternatively, use [`MetadataBuilder`](struct.MetadataBuilder.html):

+///

+/// ```edition2018

+/// use log::{Record, Level, MetadataBuilder};

+///

+/// let error_metadata = MetadataBuilder::new()

+///                         .target("myApp")

+///                         .level(Level::Error)

+///                         .build();

+///

+/// let record = Record::builder()

+///                 .metadata(error_metadata)

+///                 .args(format_args!("Error!"))

+///                 .line(Some(433))

+///                 .file(Some("app.rs"))

+///                 .module_path(Some("server"))

+///                 .build();

+/// ```

+#[derive(Debug)]

+pub struct RecordBuilder<'a> {

+    record: Record<'a>,

+}

+

+impl<'a> RecordBuilder<'a> {

+    /// Construct new `RecordBuilder`.

+    ///

+    /// The default options are:

+    ///

+    /// - `args`: [`format_args!("")`]

+    /// - `metadata`: [`Metadata::builder().build()`]

+    /// - `module_path`: `None`

+    /// - `file`: `None`

+    /// - `line`: `None`

+    ///

+    /// [`format_args!("")`]: https://doc.rust-lang.org/std/macro.format_args.html

+    /// [`Metadata::builder().build()`]: struct.MetadataBuilder.html#method.build

+    #[inline]

+    pub fn new() -> RecordBuilder<'a> {

+        RecordBuilder {

+            record: Record {

+                args: format_args!(""),

+                metadata: Metadata::builder().build(),

+                module_path: None,

+                file: None,

+                line: None,

+                #[cfg(feature = "kv_unstable")]

+                key_values: KeyValues(&Option::None::<(kv::Key, kv::Value)>),

+            },

+        }

+    }

+

+    /// Set [`args`](struct.Record.html#method.args).

+    #[inline]

+    pub fn args(&mut self, args: fmt::Arguments<'a>) -> &mut RecordBuilder<'a> {

+        self.record.args = args;

+        self

+    }

+

+    /// Set [`metadata`](struct.Record.html#method.metadata). Construct a `Metadata` object with [`MetadataBuilder`](struct.MetadataBuilder.html).

+    #[inline]

+    pub fn metadata(&mut self, metadata: Metadata<'a>) -> &mut RecordBuilder<'a> {

+        self.record.metadata = metadata;

+        self

+    }

+

+    /// Set [`Metadata::level`](struct.Metadata.html#method.level).

+    #[inline]

+    pub fn level(&mut self, level: Level) -> &mut RecordBuilder<'a> {

+        self.record.metadata.level = level;

+        self

+    }

+

+    /// Set [`Metadata::target`](struct.Metadata.html#method.target)

+    #[inline]

+    pub fn target(&mut self, target: &'a str) -> &mut RecordBuilder<'a> {

+        self.record.metadata.target = target;

+        self

+    }

+

+    /// Set [`module_path`](struct.Record.html#method.module_path)

+    #[inline]

+    pub fn module_path(&mut self, path: Option<&'a str>) -> &mut RecordBuilder<'a> {

+        self.record.module_path = path.map(MaybeStaticStr::Borrowed);

+        self

+    }

+

+    /// Set [`module_path`](struct.Record.html#method.module_path) to a `'static` string

+    #[inline]

+    pub fn module_path_static(&mut self, path: Option<&'static str>) -> &mut RecordBuilder<'a> {

+        self.record.module_path = path.map(MaybeStaticStr::Static);

+        self

+    }

+

+    /// Set [`file`](struct.Record.html#method.file)

+    #[inline]

+    pub fn file(&mut self, file: Option<&'a str>) -> &mut RecordBuilder<'a> {

+        self.record.file = file.map(MaybeStaticStr::Borrowed);

+        self

+    }

+

+    /// Set [`file`](struct.Record.html#method.file) to a `'static` string.

+    #[inline]

+    pub fn file_static(&mut self, file: Option<&'static str>) -> &mut RecordBuilder<'a> {

+        self.record.file = file.map(MaybeStaticStr::Static);

+        self

+    }

+

+    /// Set [`line`](struct.Record.html#method.line)

+    #[inline]

+    pub fn line(&mut self, line: Option<u32>) -> &mut RecordBuilder<'a> {

+        self.record.line = line;

+        self

+    }

+

+    /// Set [`key_values`](struct.Record.html#method.key_values)

+    #[cfg(feature = "kv_unstable")]

+    #[inline]

+    pub fn key_values(&mut self, kvs: &'a dyn kv::Source) -> &mut RecordBuilder<'a> {

+        self.record.key_values = KeyValues(kvs);

+        self

+    }

+

+    /// Invoke the builder and return a `Record`

+    #[inline]

+    pub fn build(&self) -> Record<'a> {

+        self.record.clone()

+    }

+}

+

+/// Metadata about a log message.

+///

+/// # Use

+///

+/// `Metadata` structs are created when users of the library use

+/// logging macros.

+///

+/// They are consumed by implementations of the `Log` trait in the

+/// `enabled` method.

+///

+/// `Record`s use `Metadata` to determine the log message's severity

+/// and target.

+///

+/// Users should use the `log_enabled!` macro in their code to avoid

+/// constructing expensive log messages.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::{Record, Level, Metadata};

+///

+/// struct MyLogger;

+///

+/// impl log::Log for MyLogger {

+///     fn enabled(&self, metadata: &Metadata) -> bool {

+///         metadata.level() <= Level::Info

+///     }

+///

+///     fn log(&self, record: &Record) {

+///         if self.enabled(record.metadata()) {

+///             println!("{} - {}", record.level(), record.args());

+///         }

+///     }

+///     fn flush(&self) {}

+/// }

+///

+/// # fn main(){}

+/// ```

+#[derive(Clone, Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]

+pub struct Metadata<'a> {

+    level: Level,

+    target: &'a str,

+}

+

+impl<'a> Metadata<'a> {

+    /// Returns a new builder.

+    #[inline]

+    pub fn builder() -> MetadataBuilder<'a> {

+        MetadataBuilder::new()

+    }

+

+    /// The verbosity level of the message.

+    #[inline]

+    pub fn level(&self) -> Level {

+        self.level

+    }

+

+    /// The name of the target of the directive.

+    #[inline]

+    pub fn target(&self) -> &'a str {

+        self.target

+    }

+}

+

+/// Builder for [`Metadata`](struct.Metadata.html).

+///

+/// Typically should only be used by log library creators or for testing and "shim loggers".

+/// The `MetadataBuilder` can set the different parameters of a `Metadata` object, and returns

+/// the created object when `build` is called.

+///

+/// # Example

+///

+/// ```edition2018

+/// let target = "myApp";

+/// use log::{Level, MetadataBuilder};

+/// let metadata = MetadataBuilder::new()

+///                     .level(Level::Debug)

+///                     .target(target)

+///                     .build();

+/// ```

+#[derive(Eq, PartialEq, Ord, PartialOrd, Hash, Debug)]

+pub struct MetadataBuilder<'a> {

+    metadata: Metadata<'a>,

+}

+

+impl<'a> MetadataBuilder<'a> {

+    /// Construct a new `MetadataBuilder`.

+    ///

+    /// The default options are:

+    ///

+    /// - `level`: `Level::Info`

+    /// - `target`: `""`

+    #[inline]

+    pub fn new() -> MetadataBuilder<'a> {

+        MetadataBuilder {

+            metadata: Metadata {

+                level: Level::Info,

+                target: "",

+            },

+        }

+    }

+

+    /// Setter for [`level`](struct.Metadata.html#method.level).

+    #[inline]

+    pub fn level(&mut self, arg: Level) -> &mut MetadataBuilder<'a> {

+        self.metadata.level = arg;

+        self

+    }

+

+    /// Setter for [`target`](struct.Metadata.html#method.target).

+    #[inline]

+    pub fn target(&mut self, target: &'a str) -> &mut MetadataBuilder<'a> {

+        self.metadata.target = target;

+        self

+    }

+

+    /// Returns a `Metadata` object.

+    #[inline]

+    pub fn build(&self) -> Metadata<'a> {

+        self.metadata.clone()

+    }

+}

+

+/// A trait encapsulating the operations required of a logger.

+pub trait Log: Sync + Send {

+    /// Determines if a log message with the specified metadata would be

+    /// logged.

+    ///

+    /// This is used by the `log_enabled!` macro to allow callers to avoid

+    /// expensive computation of log message arguments if the message would be

+    /// discarded anyway.

+    fn enabled(&self, metadata: &Metadata) -> bool;

+

+    /// Logs the `Record`.

+    ///

+    /// Note that `enabled` is *not* necessarily called before this method.

+    /// Implementations of `log` should perform all necessary filtering

+    /// internally.

+    fn log(&self, record: &Record);

+

+    /// Flushes any buffered records.

+    fn flush(&self);

+}

+

+// Just used as a dummy initial value for LOGGER

+struct NopLogger;

+

+impl Log for NopLogger {

+    fn enabled(&self, _: &Metadata) -> bool {

+        false

+    }

+

+    fn log(&self, _: &Record) {}

+    fn flush(&self) {}

+}

+

+/// Sets the global maximum log level.

+///

+/// Generally, this should only be called by the active logging implementation.

+#[inline]

+pub fn set_max_level(level: LevelFilter) {

+    MAX_LOG_LEVEL_FILTER.store(level as usize, Ordering::SeqCst)

+}

+

+/// Returns the current maximum log level.

+///

+/// The [`log!`], [`error!`], [`warn!`], [`info!`], [`debug!`], and [`trace!`] macros check

+/// this value and discard any message logged at a higher level. The maximum

+/// log level is set by the [`set_max_level`] function.

+///

+/// [`log!`]: macro.log.html

+/// [`error!`]: macro.error.html

+/// [`warn!`]: macro.warn.html

+/// [`info!`]: macro.info.html

+/// [`debug!`]: macro.debug.html

+/// [`trace!`]: macro.trace.html

+/// [`set_max_level`]: fn.set_max_level.html

+#[inline(always)]

+pub fn max_level() -> LevelFilter {

+    // Since `LevelFilter` is `repr(usize)`,

+    // this transmute is sound if and only if `MAX_LOG_LEVEL_FILTER`

+    // is set to a usize that is a valid discriminant for `LevelFilter`.

+    // Since `MAX_LOG_LEVEL_FILTER` is private, the only time it's set

+    // is by `set_max_level` above, i.e. by casting a `LevelFilter` to `usize`.

+    // So any usize stored in `MAX_LOG_LEVEL_FILTER` is a valid discriminant.

+    unsafe { mem::transmute(MAX_LOG_LEVEL_FILTER.load(Ordering::Relaxed)) }

+}

+

+/// Sets the global logger to a `Box<Log>`.

+///

+/// This is a simple convenience wrapper over `set_logger`, which takes a

+/// `Box<Log>` rather than a `&'static Log`. See the documentation for

+/// [`set_logger`] for more details.

+///

+/// Requires the `std` feature.

+///

+/// # Errors

+///

+/// An error is returned if a logger has already been set.

+///

+/// [`set_logger`]: fn.set_logger.html

+#[cfg(all(feature = "std", atomic_cas))]

+pub fn set_boxed_logger(logger: Box<dyn Log>) -> Result<(), SetLoggerError> {

+    set_logger_inner(|| Box::leak(logger))

+}

+

+/// Sets the global logger to a `&'static Log`.

+///

+/// This function may only be called once in the lifetime of a program. Any log

+/// events that occur before the call to `set_logger` completes will be ignored.

+///

+/// This function does not typically need to be called manually. Logger

+/// implementations should provide an initialization method that installs the

+/// logger internally.

+///

+/// # Availability

+///

+/// This method is available even when the `std` feature is disabled. However,

+/// it is currently unavailable on `thumbv6` targets, which lack support for

+/// some atomic operations which are used by this function. Even on those

+/// targets, [`set_logger_racy`] will be available.

+///

+/// # Errors

+///

+/// An error is returned if a logger has already been set.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::{error, info, warn, Record, Level, Metadata, LevelFilter};

+///

+/// static MY_LOGGER: MyLogger = MyLogger;

+///

+/// struct MyLogger;

+///

+/// impl log::Log for MyLogger {

+///     fn enabled(&self, metadata: &Metadata) -> bool {

+///         metadata.level() <= Level::Info

+///     }

+///

+///     fn log(&self, record: &Record) {

+///         if self.enabled(record.metadata()) {

+///             println!("{} - {}", record.level(), record.args());

+///         }

+///     }

+///     fn flush(&self) {}

+/// }

+///

+/// # fn main(){

+/// log::set_logger(&MY_LOGGER).unwrap();

+/// log::set_max_level(LevelFilter::Info);

+///

+/// info!("hello log");

+/// warn!("warning");

+/// error!("oops");

+/// # }

+/// ```

+///

+/// [`set_logger_racy`]: fn.set_logger_racy.html

+#[cfg(atomic_cas)]

+pub fn set_logger(logger: &'static dyn Log) -> Result<(), SetLoggerError> {

+    set_logger_inner(|| logger)

+}

+

+#[cfg(atomic_cas)]

+fn set_logger_inner<F>(make_logger: F) -> Result<(), SetLoggerError>

+where

+    F: FnOnce() -> &'static dyn Log,

+{

+    match STATE.compare_and_swap(UNINITIALIZED, INITIALIZING, Ordering::SeqCst) {

+        UNINITIALIZED => {

+            unsafe {

+                LOGGER = make_logger();

+            }

+            STATE.store(INITIALIZED, Ordering::SeqCst);

+            Ok(())

+        }

+        INITIALIZING => {

+            while STATE.load(Ordering::SeqCst) == INITIALIZING {

+                std::sync::atomic::spin_loop_hint();

+            }

+            Err(SetLoggerError(()))

+        }

+        _ => Err(SetLoggerError(())),

+    }

+}

+

+/// A thread-unsafe version of [`set_logger`].

+///

+/// This function is available on all platforms, even those that do not have

+/// support for atomics that is needed by [`set_logger`].

+///

+/// In almost all cases, [`set_logger`] should be preferred.

+///

+/// # Safety

+///

+/// This function is only safe to call when no other logger initialization

+/// function is called while this function still executes.

+///

+/// This can be upheld by (for example) making sure that **there are no other

+/// threads**, and (on embedded) that **interrupts are disabled**.

+///

+/// It is safe to use other logging functions while this function runs

+/// (including all logging macros).

+///

+/// [`set_logger`]: fn.set_logger.html

+pub unsafe fn set_logger_racy(logger: &'static dyn Log) -> Result<(), SetLoggerError> {

+    match STATE.load(Ordering::SeqCst) {

+        UNINITIALIZED => {

+            LOGGER = logger;

+            STATE.store(INITIALIZED, Ordering::SeqCst);

+            Ok(())

+        }

+        INITIALIZING => {

+            // This is just plain UB, since we were racing another initialization function

+            unreachable!("set_logger_racy must not be used with other initialization functions")

+        }

+        _ => Err(SetLoggerError(())),

+    }

+}

+

+/// The type returned by [`set_logger`] if [`set_logger`] has already been called.

+///

+/// [`set_logger`]: fn.set_logger.html

+#[allow(missing_copy_implementations)]

+#[derive(Debug)]

+pub struct SetLoggerError(());

+

+impl fmt::Display for SetLoggerError {

+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {

+        fmt.write_str(SET_LOGGER_ERROR)

+    }

+}

+

+// The Error trait is not available in libcore

+#[cfg(feature = "std")]

+impl error::Error for SetLoggerError {}

+

+/// The type returned by [`from_str`] when the string doesn't match any of the log levels.

+///

+/// [`from_str`]: https://doc.rust-lang.org/std/str/trait.FromStr.html#tymethod.from_str

+#[allow(missing_copy_implementations)]

+#[derive(Debug, PartialEq)]

+pub struct ParseLevelError(());

+

+impl fmt::Display for ParseLevelError {

+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {

+        fmt.write_str(LEVEL_PARSE_ERROR)

+    }

+}

+

+// The Error trait is not available in libcore

+#[cfg(feature = "std")]

+impl error::Error for ParseLevelError {}

+

+/// Returns a reference to the logger.

+///

+/// If a logger has not been set, a no-op implementation is returned.

+pub fn logger() -> &'static dyn Log {

+    if STATE.load(Ordering::SeqCst) != INITIALIZED {

+        static NOP: NopLogger = NopLogger;

+        &NOP

+    } else {

+        unsafe { LOGGER }

+    }

+}

+

+// WARNING: this is not part of the crate's public API and is subject to change at any time

+#[doc(hidden)]

+pub fn __private_api_log(

+    args: fmt::Arguments,

+    level: Level,

+    &(target, module_path, file, line): &(&str, &'static str, &'static str, u32),

+) {

+    logger().log(

+        &Record::builder()

+            .args(args)

+            .level(level)

+            .target(target)

+            .module_path_static(Some(module_path))

+            .file_static(Some(file))

+            .line(Some(line))

+            .build(),

+    );

+}

+

+// WARNING: this is not part of the crate's public API and is subject to change at any time

+#[doc(hidden)]

+pub fn __private_api_log_lit(

+    message: &str,

+    level: Level,

+    &(target, module_path, file, line): &(&str, &'static str, &'static str, u32),

+) {

+    logger().log(

+        &Record::builder()

+            .args(format_args!("{}", message))

+            .level(level)

+            .target(target)

+            .module_path_static(Some(module_path))

+            .file_static(Some(file))

+            .line(Some(line))

+            .build(),

+    );

+}

+

+// WARNING: this is not part of the crate's public API and is subject to change at any time

+#[doc(hidden)]

+pub fn __private_api_enabled(level: Level, target: &str) -> bool {

+    logger().enabled(&Metadata::builder().level(level).target(target).build())

+}

+

+/// The statically resolved maximum log level.

+///

+/// See the crate level documentation for information on how to configure this.

+///

+/// This value is checked by the log macros, but not by the `Log`ger returned by

+/// the [`logger`] function. Code that manually calls functions on that value

+/// should compare the level against this value.

+///

+/// [`logger`]: fn.logger.html

+pub const STATIC_MAX_LEVEL: LevelFilter = MAX_LEVEL_INNER;

+

+cfg_if! {

+    if #[cfg(all(not(debug_assertions), feature = "release_max_level_off"))] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Off;

+    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_error"))] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Error;

+    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_warn"))] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Warn;

+    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_info"))] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Info;

+    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_debug"))] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Debug;

+    } else if #[cfg(all(not(debug_assertions), feature = "release_max_level_trace"))] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Trace;

+    } else if #[cfg(feature = "max_level_off")] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Off;

+    } else if #[cfg(feature = "max_level_error")] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Error;

+    } else if #[cfg(feature = "max_level_warn")] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Warn;

+    } else if #[cfg(feature = "max_level_info")] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Info;

+    } else if #[cfg(feature = "max_level_debug")] {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Debug;

+    } else {

+        const MAX_LEVEL_INNER: LevelFilter = LevelFilter::Trace;

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    extern crate std;

+    use super::{Level, LevelFilter, ParseLevelError};

+    use tests::std::string::ToString;

+

+    #[test]

+    fn test_levelfilter_from_str() {

+        let tests = [

+            ("off", Ok(LevelFilter::Off)),

+            ("error", Ok(LevelFilter::Error)),

+            ("warn", Ok(LevelFilter::Warn)),

+            ("info", Ok(LevelFilter::Info)),

+            ("debug", Ok(LevelFilter::Debug)),

+            ("trace", Ok(LevelFilter::Trace)),

+            ("OFF", Ok(LevelFilter::Off)),

+            ("ERROR", Ok(LevelFilter::Error)),

+            ("WARN", Ok(LevelFilter::Warn)),

+            ("INFO", Ok(LevelFilter::Info)),

+            ("DEBUG", Ok(LevelFilter::Debug)),

+            ("TRACE", Ok(LevelFilter::Trace)),

+            ("asdf", Err(ParseLevelError(()))),

+        ];

+        for &(s, ref expected) in &tests {

+            assert_eq!(expected, &s.parse());

+        }

+    }

+

+    #[test]

+    fn test_level_from_str() {

+        let tests = [

+            ("OFF", Err(ParseLevelError(()))),

+            ("error", Ok(Level::Error)),

+            ("warn", Ok(Level::Warn)),

+            ("info", Ok(Level::Info)),

+            ("debug", Ok(Level::Debug)),

+            ("trace", Ok(Level::Trace)),

+            ("ERROR", Ok(Level::Error)),

+            ("WARN", Ok(Level::Warn)),

+            ("INFO", Ok(Level::Info)),

+            ("DEBUG", Ok(Level::Debug)),

+            ("TRACE", Ok(Level::Trace)),

+            ("asdf", Err(ParseLevelError(()))),

+        ];

+        for &(s, ref expected) in &tests {

+            assert_eq!(expected, &s.parse());

+        }

+    }

+

+    #[test]

+    fn test_level_show() {

+        assert_eq!("INFO", Level::Info.to_string());

+        assert_eq!("ERROR", Level::Error.to_string());

+    }

+

+    #[test]

+    fn test_levelfilter_show() {

+        assert_eq!("OFF", LevelFilter::Off.to_string());

+        assert_eq!("ERROR", LevelFilter::Error.to_string());

+    }

+

+    #[test]

+    fn test_cross_cmp() {

+        assert!(Level::Debug > LevelFilter::Error);

+        assert!(LevelFilter::Warn < Level::Trace);

+        assert!(LevelFilter::Off < Level::Error);

+    }

+

+    #[test]

+    fn test_cross_eq() {

+        assert!(Level::Error == LevelFilter::Error);

+        assert!(LevelFilter::Off != Level::Error);

+        assert!(Level::Trace == LevelFilter::Trace);

+    }

+

+    #[test]

+    fn test_to_level() {

+        assert_eq!(Some(Level::Error), LevelFilter::Error.to_level());

+        assert_eq!(None, LevelFilter::Off.to_level());

+        assert_eq!(Some(Level::Debug), LevelFilter::Debug.to_level());

+    }

+

+    #[test]

+    fn test_to_level_filter() {

+        assert_eq!(LevelFilter::Error, Level::Error.to_level_filter());

+        assert_eq!(LevelFilter::Trace, Level::Trace.to_level_filter());

+    }

+

+    #[test]

+    #[cfg(feature = "std")]

+    fn test_error_trait() {

+        use super::SetLoggerError;

+        let e = SetLoggerError(());

+        assert_eq!(

+            &e.to_string(),

+            "attempted to set a logger after the logging system \

+             was already initialized"

+        );

+    }

+

+    #[test]

+    fn test_metadata_builder() {

+        use super::MetadataBuilder;

+        let target = "myApp";

+        let metadata_test = MetadataBuilder::new()

+            .level(Level::Debug)

+            .target(target)

+            .build();

+        assert_eq!(metadata_test.level(), Level::Debug);

+        assert_eq!(metadata_test.target(), "myApp");

+    }

+

+    #[test]

+    fn test_metadata_convenience_builder() {

+        use super::Metadata;

+        let target = "myApp";

+        let metadata_test = Metadata::builder()

+            .level(Level::Debug)

+            .target(target)

+            .build();

+        assert_eq!(metadata_test.level(), Level::Debug);

+        assert_eq!(metadata_test.target(), "myApp");

+    }

+

+    #[test]

+    fn test_record_builder() {

+        use super::{MetadataBuilder, RecordBuilder};

+        let target = "myApp";

+        let metadata = MetadataBuilder::new().target(target).build();

+        let fmt_args = format_args!("hello");

+        let record_test = RecordBuilder::new()

+            .args(fmt_args)

+            .metadata(metadata)

+            .module_path(Some("foo"))

+            .file(Some("bar"))

+            .line(Some(30))

+            .build();

+        assert_eq!(record_test.metadata().target(), "myApp");

+        assert_eq!(record_test.module_path(), Some("foo"));

+        assert_eq!(record_test.file(), Some("bar"));

+        assert_eq!(record_test.line(), Some(30));

+    }

+

+    #[test]

+    fn test_record_convenience_builder() {

+        use super::{Metadata, Record};

+        let target = "myApp";

+        let metadata = Metadata::builder().target(target).build();

+        let fmt_args = format_args!("hello");

+        let record_test = Record::builder()

+            .args(fmt_args)

+            .metadata(metadata)

+            .module_path(Some("foo"))

+            .file(Some("bar"))

+            .line(Some(30))

+            .build();

+        assert_eq!(record_test.target(), "myApp");

+        assert_eq!(record_test.module_path(), Some("foo"));

+        assert_eq!(record_test.file(), Some("bar"));

+        assert_eq!(record_test.line(), Some(30));

+    }

+

+    #[test]

+    fn test_record_complete_builder() {

+        use super::{Level, Record};

+        let target = "myApp";

+        let record_test = Record::builder()

+            .module_path(Some("foo"))

+            .file(Some("bar"))

+            .line(Some(30))

+            .target(target)

+            .level(Level::Error)

+            .build();

+        assert_eq!(record_test.target(), "myApp");

+        assert_eq!(record_test.level(), Level::Error);

+        assert_eq!(record_test.module_path(), Some("foo"));

+        assert_eq!(record_test.file(), Some("bar"));

+        assert_eq!(record_test.line(), Some(30));

+    }

+

+    #[test]

+    #[cfg(feature = "kv_unstable")]

+    fn test_record_key_values_builder() {

+        use super::Record;

+        use kv::{self, Visitor};

+

+        struct TestVisitor {

+            seen_pairs: usize,

+        }

+

+        impl<'kvs> Visitor<'kvs> for TestVisitor {

+            fn visit_pair(

+                &mut self,

+                _: kv::Key<'kvs>,

+                _: kv::Value<'kvs>,

+            ) -> Result<(), kv::Error> {

+                self.seen_pairs += 1;

+                Ok(())

+            }

+        }

+

+        let kvs: &[(&str, i32)] = &[("a", 1), ("b", 2)];

+        let record_test = Record::builder().key_values(&kvs).build();

+

+        let mut visitor = TestVisitor { seen_pairs: 0 };

+

+        record_test.key_values().visit(&mut visitor).unwrap();

+

+        assert_eq!(2, visitor.seen_pairs);

+    }

+

+    #[test]

+    #[cfg(feature = "kv_unstable")]

+    fn test_record_key_values_get_coerce() {

+        use super::Record;

+

+        let kvs: &[(&str, &str)] = &[("a", "1"), ("b", "2")];

+        let record = Record::builder().key_values(&kvs).build();

+

+        assert_eq!(

+            "2",

+            record

+                .key_values()

+                .get("b".into())

+                .expect("missing key")

+                .to_borrowed_str()

+                .expect("invalid value")

+        );

+    }

+}

diff --git a/src/macros.rs b/src/macros.rs
index bb40b71..48de437 100644
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -1,250 +1,262 @@
-// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT
-// file at the top-level directory of this distribution and at
-// http://rust-lang.org/COPYRIGHT.
-//
-// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
-// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
-// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
-// option. This file may not be copied, modified, or distributed
-// except according to those terms.
-
-/// The standard logging macro.
-///
-/// This macro will generically log with the specified `Level` and `format!`
-/// based argument list.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::{log, Level};
-///
-/// # fn main() {
-/// let data = (42, "Forty-two");
-/// let private_data = "private";
-///
-/// log!(Level::Error, "Received errors: {}, {}", data.0, data.1);
-/// log!(target: "app_events", Level::Warn, "App warning: {}, {}, {}",
-///     data.0, data.1, private_data);
-/// # }
-/// ```
-#[macro_export(local_inner_macros)]
-macro_rules! log {
-    (target: $target:expr, $lvl:expr, $($arg:tt)+) => ({
-        let lvl = $lvl;
-        if lvl <= $crate::STATIC_MAX_LEVEL && lvl <= $crate::max_level() {
-            $crate::__private_api_log(
-                __log_format_args!($($arg)+),
-                lvl,
-                &($target, __log_module_path!(), __log_file!(), __log_line!()),
-            );
-        }
-    });
-    ($lvl:expr, $($arg:tt)+) => (log!(target: __log_module_path!(), $lvl, $($arg)+))
-}
-
-/// Logs a message at the error level.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::error;
-///
-/// # fn main() {
-/// let (err_info, port) = ("No connection", 22);
-///
-/// error!("Error: {} on port {}", err_info, port);
-/// error!(target: "app_events", "App Error: {}, Port: {}", err_info, 22);
-/// # }
-/// ```
-#[macro_export(local_inner_macros)]
-macro_rules! error {
-    (target: $target:expr, $($arg:tt)+) => (
-        log!(target: $target, $crate::Level::Error, $($arg)+);
-    );
-    ($($arg:tt)+) => (
-        log!($crate::Level::Error, $($arg)+);
-    )
-}
-
-/// Logs a message at the warn level.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::warn;
-///
-/// # fn main() {
-/// let warn_description = "Invalid Input";
-///
-/// warn!("Warning! {}!", warn_description);
-/// warn!(target: "input_events", "App received warning: {}", warn_description);
-/// # }
-/// ```
-#[macro_export(local_inner_macros)]
-macro_rules! warn {
-    (target: $target:expr, $($arg:tt)+) => (
-        log!(target: $target, $crate::Level::Warn, $($arg)+);
-    );
-    ($($arg:tt)+) => (
-        log!($crate::Level::Warn, $($arg)+);
-    )
-}
-
-/// Logs a message at the info level.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::info;
-///
-/// # fn main() {
-/// # struct Connection { port: u32, speed: f32 }
-/// let conn_info = Connection { port: 40, speed: 3.20 };
-///
-/// info!("Connected to port {} at {} Mb/s", conn_info.port, conn_info.speed);
-/// info!(target: "connection_events", "Successfull connection, port: {}, speed: {}",
-///       conn_info.port, conn_info.speed);
-/// # }
-/// ```
-#[macro_export(local_inner_macros)]
-macro_rules! info {
-    (target: $target:expr, $($arg:tt)+) => (
-        log!(target: $target, $crate::Level::Info, $($arg)+);
-    );
-    ($($arg:tt)+) => (
-        log!($crate::Level::Info, $($arg)+);
-    )
-}
-
-/// Logs a message at the debug level.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::debug;
-///
-/// # fn main() {
-/// # struct Position { x: f32, y: f32 }
-/// let pos = Position { x: 3.234, y: -1.223 };
-///
-/// debug!("New position: x: {}, y: {}", pos.x, pos.y);
-/// debug!(target: "app_events", "New position: x: {}, y: {}", pos.x, pos.y);
-/// # }
-/// ```
-#[macro_export(local_inner_macros)]
-macro_rules! debug {
-    (target: $target:expr, $($arg:tt)+) => (
-        log!(target: $target, $crate::Level::Debug, $($arg)+);
-    );
-    ($($arg:tt)+) => (
-        log!($crate::Level::Debug, $($arg)+);
-    )
-}
-
-/// Logs a message at the trace level.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::trace;
-///
-/// # fn main() {
-/// # struct Position { x: f32, y: f32 }
-/// let pos = Position { x: 3.234, y: -1.223 };
-///
-/// trace!("Position is: x: {}, y: {}", pos.x, pos.y);
-/// trace!(target: "app_events", "x is {} and y is {}",
-///        if pos.x >= 0.0 { "positive" } else { "negative" },
-///        if pos.y >= 0.0 { "positive" } else { "negative" });
-/// # }
-/// ```
-#[macro_export(local_inner_macros)]
-macro_rules! trace {
-    (target: $target:expr, $($arg:tt)+) => (
-        log!(target: $target, $crate::Level::Trace, $($arg)+);
-    );
-    ($($arg:tt)+) => (
-        log!($crate::Level::Trace, $($arg)+);
-    )
-}
-
-/// Determines if a message logged at the specified level in that module will
-/// be logged.
-///
-/// This can be used to avoid expensive computation of log message arguments if
-/// the message would be ignored anyway.
-///
-/// # Examples
-///
-/// ```edition2018
-/// use log::Level::Debug;
-/// use log::{debug, log_enabled};
-///
-/// # fn foo() {
-/// if log_enabled!(Debug) {
-///     let data = expensive_call();
-///     debug!("expensive debug data: {} {}", data.x, data.y);
-/// }
-/// if log_enabled!(target: "Global", Debug) {
-///    let data = expensive_call();
-///    debug!(target: "Global", "expensive debug data: {} {}", data.x, data.y);
-/// }
-/// # }
-/// # struct Data { x: u32, y: u32 }
-/// # fn expensive_call() -> Data { Data { x: 0, y: 0 } }
-/// # fn main() {}
-/// ```
-#[macro_export(local_inner_macros)]
-macro_rules! log_enabled {
-    (target: $target:expr, $lvl:expr) => {{
-        let lvl = $lvl;
-        lvl <= $crate::STATIC_MAX_LEVEL
-            && lvl <= $crate::max_level()
-            && $crate::__private_api_enabled(lvl, $target)
-    }};
-    ($lvl:expr) => {
-        log_enabled!(target: __log_module_path!(), $lvl)
-    };
-}
-
-// The log macro above cannot invoke format_args directly because it uses
-// local_inner_macros. A format_args invocation there would resolve to
-// $crate::format_args which does not exist. Instead invoke format_args here
-// outside of local_inner_macros so that it resolves (probably) to
-// core::format_args or std::format_args. Same for the several macros that
-// follow.
-//
-// This is a workaround until we drop support for pre-1.30 compilers. At that
-// point we can remove use of local_inner_macros, use $crate:: when invoking
-// local macros, and invoke format_args directly.
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __log_format_args {
-    ($($args:tt)*) => {
-        format_args!($($args)*)
-    };
-}
-
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __log_module_path {
-    () => {
-        module_path!()
-    };
-}
-
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __log_file {
-    () => {
-        file!()
-    };
-}
-
-#[doc(hidden)]
-#[macro_export]
-macro_rules! __log_line {
-    () => {
-        line!()
-    };
-}
+// Copyright 2014-2015 The Rust Project Developers. See the COPYRIGHT

+// file at the top-level directory of this distribution and at

+// http://rust-lang.org/COPYRIGHT.

+//

+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or

+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license

+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your

+// option. This file may not be copied, modified, or distributed

+// except according to those terms.

+

+/// The standard logging macro.

+///

+/// This macro will generically log with the specified `Level` and `format!`

+/// based argument list.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::{log, Level};

+///

+/// # fn main() {

+/// let data = (42, "Forty-two");

+/// let private_data = "private";

+///

+/// log!(Level::Error, "Received errors: {}, {}", data.0, data.1);

+/// log!(target: "app_events", Level::Warn, "App warning: {}, {}, {}",

+///     data.0, data.1, private_data);

+/// # }

+/// ```

+#[macro_export(local_inner_macros)]

+macro_rules! log {

+    (target: $target:expr, $lvl:expr, $message:expr) => ({

+        let lvl = $lvl;

+        if lvl <= $crate::STATIC_MAX_LEVEL && lvl <= $crate::max_level() {

+            // ensure that $message is a valid format string literal

+            let _ = __log_format_args!($message);

+            $crate::__private_api_log_lit(

+                $message,

+                lvl,

+                &($target, __log_module_path!(), __log_file!(), __log_line!()),

+            );

+        }

+    });

+    (target: $target:expr, $lvl:expr, $($arg:tt)+) => ({

+        let lvl = $lvl;

+        if lvl <= $crate::STATIC_MAX_LEVEL && lvl <= $crate::max_level() {

+            $crate::__private_api_log(

+                __log_format_args!($($arg)+),

+                lvl,

+                &($target, __log_module_path!(), __log_file!(), __log_line!()),

+            );

+        }

+    });

+    ($lvl:expr, $($arg:tt)+) => (log!(target: __log_module_path!(), $lvl, $($arg)+))

+}

+

+/// Logs a message at the error level.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::error;

+///

+/// # fn main() {

+/// let (err_info, port) = ("No connection", 22);

+///

+/// error!("Error: {} on port {}", err_info, port);

+/// error!(target: "app_events", "App Error: {}, Port: {}", err_info, 22);

+/// # }

+/// ```

+#[macro_export(local_inner_macros)]

+macro_rules! error {

+    (target: $target:expr, $($arg:tt)+) => (

+        log!(target: $target, $crate::Level::Error, $($arg)+);

+    );

+    ($($arg:tt)+) => (

+        log!($crate::Level::Error, $($arg)+);

+    )

+}

+

+/// Logs a message at the warn level.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::warn;

+///

+/// # fn main() {

+/// let warn_description = "Invalid Input";

+///

+/// warn!("Warning! {}!", warn_description);

+/// warn!(target: "input_events", "App received warning: {}", warn_description);

+/// # }

+/// ```

+#[macro_export(local_inner_macros)]

+macro_rules! warn {

+    (target: $target:expr, $($arg:tt)+) => (

+        log!(target: $target, $crate::Level::Warn, $($arg)+);

+    );

+    ($($arg:tt)+) => (

+        log!($crate::Level::Warn, $($arg)+);

+    )

+}

+

+/// Logs a message at the info level.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::info;

+///

+/// # fn main() {

+/// # struct Connection { port: u32, speed: f32 }

+/// let conn_info = Connection { port: 40, speed: 3.20 };

+///

+/// info!("Connected to port {} at {} Mb/s", conn_info.port, conn_info.speed);

+/// info!(target: "connection_events", "Successfull connection, port: {}, speed: {}",

+///       conn_info.port, conn_info.speed);

+/// # }

+/// ```

+#[macro_export(local_inner_macros)]

+macro_rules! info {

+    (target: $target:expr, $($arg:tt)+) => (

+        log!(target: $target, $crate::Level::Info, $($arg)+);

+    );

+    ($($arg:tt)+) => (

+        log!($crate::Level::Info, $($arg)+);

+    )

+}

+

+/// Logs a message at the debug level.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::debug;

+///

+/// # fn main() {

+/// # struct Position { x: f32, y: f32 }

+/// let pos = Position { x: 3.234, y: -1.223 };

+///

+/// debug!("New position: x: {}, y: {}", pos.x, pos.y);

+/// debug!(target: "app_events", "New position: x: {}, y: {}", pos.x, pos.y);

+/// # }

+/// ```

+#[macro_export(local_inner_macros)]

+macro_rules! debug {

+    (target: $target:expr, $($arg:tt)+) => (

+        log!(target: $target, $crate::Level::Debug, $($arg)+);

+    );

+    ($($arg:tt)+) => (

+        log!($crate::Level::Debug, $($arg)+);

+    )

+}

+

+/// Logs a message at the trace level.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::trace;

+///

+/// # fn main() {

+/// # struct Position { x: f32, y: f32 }

+/// let pos = Position { x: 3.234, y: -1.223 };

+///

+/// trace!("Position is: x: {}, y: {}", pos.x, pos.y);

+/// trace!(target: "app_events", "x is {} and y is {}",

+///        if pos.x >= 0.0 { "positive" } else { "negative" },

+///        if pos.y >= 0.0 { "positive" } else { "negative" });

+/// # }

+/// ```

+#[macro_export(local_inner_macros)]

+macro_rules! trace {

+    (target: $target:expr, $($arg:tt)+) => (

+        log!(target: $target, $crate::Level::Trace, $($arg)+);

+    );

+    ($($arg:tt)+) => (

+        log!($crate::Level::Trace, $($arg)+);

+    )

+}

+

+/// Determines if a message logged at the specified level in that module will

+/// be logged.

+///

+/// This can be used to avoid expensive computation of log message arguments if

+/// the message would be ignored anyway.

+///

+/// # Examples

+///

+/// ```edition2018

+/// use log::Level::Debug;

+/// use log::{debug, log_enabled};

+///

+/// # fn foo() {

+/// if log_enabled!(Debug) {

+///     let data = expensive_call();

+///     debug!("expensive debug data: {} {}", data.x, data.y);

+/// }

+/// if log_enabled!(target: "Global", Debug) {

+///    let data = expensive_call();

+///    debug!(target: "Global", "expensive debug data: {} {}", data.x, data.y);

+/// }

+/// # }

+/// # struct Data { x: u32, y: u32 }

+/// # fn expensive_call() -> Data { Data { x: 0, y: 0 } }

+/// # fn main() {}

+/// ```

+#[macro_export(local_inner_macros)]

+macro_rules! log_enabled {

+    (target: $target:expr, $lvl:expr) => {{

+        let lvl = $lvl;

+        lvl <= $crate::STATIC_MAX_LEVEL

+            && lvl <= $crate::max_level()

+            && $crate::__private_api_enabled(lvl, $target)

+    }};

+    ($lvl:expr) => {

+        log_enabled!(target: __log_module_path!(), $lvl)

+    };

+}

+

+// The log macro above cannot invoke format_args directly because it uses

+// local_inner_macros. A format_args invocation there would resolve to

+// $crate::format_args which does not exist. Instead invoke format_args here

+// outside of local_inner_macros so that it resolves (probably) to

+// core::format_args or std::format_args. Same for the several macros that

+// follow.

+//

+// This is a workaround until we drop support for pre-1.30 compilers. At that

+// point we can remove use of local_inner_macros, use $crate:: when invoking

+// local macros, and invoke format_args directly.

+#[doc(hidden)]

+#[macro_export]

+macro_rules! __log_format_args {

+    ($($args:tt)*) => {

+        format_args!($($args)*)

+    };

+}

+

+#[doc(hidden)]

+#[macro_export]

+macro_rules! __log_module_path {

+    () => {

+        module_path!()

+    };

+}

+

+#[doc(hidden)]

+#[macro_export]

+macro_rules! __log_file {

+    () => {

+        file!()

+    };

+}

+

+#[doc(hidden)]

+#[macro_export]

+macro_rules! __log_line {

+    () => {

+        line!()

+    };

+}

diff --git a/src/serde.rs b/src/serde.rs
index efc9f14..8320ce1 100644
--- a/src/serde.rs
+++ b/src/serde.rs
@@ -1,329 +1,329 @@
-#![cfg(feature = "serde")]
-
-extern crate serde;
-use self::serde::de::{
-    Deserialize, DeserializeSeed, Deserializer, EnumAccess, Error, Unexpected, VariantAccess,
-    Visitor,
-};
-use self::serde::ser::{Serialize, Serializer};
-
-use {Level, LevelFilter, LOG_LEVEL_NAMES};
-
-use std::fmt;
-use std::str::{self, FromStr};
-
-// The Deserialize impls are handwritten to be case insensitive using FromStr.
-
-impl Serialize for Level {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        match *self {
-            Level::Error => serializer.serialize_unit_variant("Level", 0, "ERROR"),
-            Level::Warn => serializer.serialize_unit_variant("Level", 1, "WARN"),
-            Level::Info => serializer.serialize_unit_variant("Level", 2, "INFO"),
-            Level::Debug => serializer.serialize_unit_variant("Level", 3, "DEBUG"),
-            Level::Trace => serializer.serialize_unit_variant("Level", 4, "TRACE"),
-        }
-    }
-}
-
-impl<'de> Deserialize<'de> for Level {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        struct LevelIdentifier;
-
-        impl<'de> Visitor<'de> for LevelIdentifier {
-            type Value = Level;
-
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                formatter.write_str("log level")
-            }
-
-            fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
-            where
-                E: Error,
-            {
-                // Case insensitive.
-                FromStr::from_str(s).map_err(|_| Error::unknown_variant(s, &LOG_LEVEL_NAMES[1..]))
-            }
-
-            fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
-            where
-                E: Error,
-            {
-                let variant = str::from_utf8(value)
-                    .map_err(|_| Error::invalid_value(Unexpected::Bytes(value), &self))?;
-
-                self.visit_str(variant)
-            }
-        }
-
-        impl<'de> DeserializeSeed<'de> for LevelIdentifier {
-            type Value = Level;
-
-            fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
-            where
-                D: Deserializer<'de>,
-            {
-                deserializer.deserialize_identifier(LevelIdentifier)
-            }
-        }
-
-        struct LevelEnum;
-
-        impl<'de> Visitor<'de> for LevelEnum {
-            type Value = Level;
-
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                formatter.write_str("log level")
-            }
-
-            fn visit_enum<A>(self, value: A) -> Result<Self::Value, A::Error>
-            where
-                A: EnumAccess<'de>,
-            {
-                let (level, variant) = value.variant_seed(LevelIdentifier)?;
-                // Every variant is a unit variant.
-                variant.unit_variant()?;
-                Ok(level)
-            }
-        }
-
-        deserializer.deserialize_enum("Level", &LOG_LEVEL_NAMES[1..], LevelEnum)
-    }
-}
-
-impl Serialize for LevelFilter {
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        match *self {
-            LevelFilter::Off => serializer.serialize_unit_variant("LevelFilter", 0, "OFF"),
-            LevelFilter::Error => serializer.serialize_unit_variant("LevelFilter", 1, "ERROR"),
-            LevelFilter::Warn => serializer.serialize_unit_variant("LevelFilter", 2, "WARN"),
-            LevelFilter::Info => serializer.serialize_unit_variant("LevelFilter", 3, "INFO"),
-            LevelFilter::Debug => serializer.serialize_unit_variant("LevelFilter", 4, "DEBUG"),
-            LevelFilter::Trace => serializer.serialize_unit_variant("LevelFilter", 5, "TRACE"),
-        }
-    }
-}
-
-impl<'de> Deserialize<'de> for LevelFilter {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        struct LevelFilterIdentifier;
-
-        impl<'de> Visitor<'de> for LevelFilterIdentifier {
-            type Value = LevelFilter;
-
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                formatter.write_str("log level filter")
-            }
-
-            fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
-            where
-                E: Error,
-            {
-                // Case insensitive.
-                FromStr::from_str(s).map_err(|_| Error::unknown_variant(s, &LOG_LEVEL_NAMES))
-            }
-
-            fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>
-            where
-                E: Error,
-            {
-                let variant = str::from_utf8(value)
-                    .map_err(|_| Error::invalid_value(Unexpected::Bytes(value), &self))?;
-
-                self.visit_str(variant)
-            }
-        }
-
-        impl<'de> DeserializeSeed<'de> for LevelFilterIdentifier {
-            type Value = LevelFilter;
-
-            fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>
-            where
-                D: Deserializer<'de>,
-            {
-                deserializer.deserialize_identifier(LevelFilterIdentifier)
-            }
-        }
-
-        struct LevelFilterEnum;
-
-        impl<'de> Visitor<'de> for LevelFilterEnum {
-            type Value = LevelFilter;
-
-            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
-                formatter.write_str("log level filter")
-            }
-
-            fn visit_enum<A>(self, value: A) -> Result<Self::Value, A::Error>
-            where
-                A: EnumAccess<'de>,
-            {
-                let (level_filter, variant) = value.variant_seed(LevelFilterIdentifier)?;
-                // Every variant is a unit variant.
-                variant.unit_variant()?;
-                Ok(level_filter)
-            }
-        }
-
-        deserializer.deserialize_enum("LevelFilter", &LOG_LEVEL_NAMES, LevelFilterEnum)
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    extern crate serde_test;
-    use self::serde_test::{assert_de_tokens, assert_de_tokens_error, assert_tokens, Token};
-
-    use {Level, LevelFilter};
-
-    fn level_token(variant: &'static str) -> Token {
-        Token::UnitVariant {
-            name: "Level",
-            variant: variant,
-        }
-    }
-
-    fn level_bytes_tokens(variant: &'static [u8]) -> [Token; 3] {
-        [
-            Token::Enum { name: "Level" },
-            Token::Bytes(variant),
-            Token::Unit,
-        ]
-    }
-
-    fn level_filter_token(variant: &'static str) -> Token {
-        Token::UnitVariant {
-            name: "LevelFilter",
-            variant: variant,
-        }
-    }
-
-    fn level_filter_bytes_tokens(variant: &'static [u8]) -> [Token; 3] {
-        [
-            Token::Enum {
-                name: "LevelFilter",
-            },
-            Token::Bytes(variant),
-            Token::Unit,
-        ]
-    }
-
-    #[test]
-    fn test_level_ser_de() {
-        let cases = [
-            (Level::Error, [level_token("ERROR")]),
-            (Level::Warn, [level_token("WARN")]),
-            (Level::Info, [level_token("INFO")]),
-            (Level::Debug, [level_token("DEBUG")]),
-            (Level::Trace, [level_token("TRACE")]),
-        ];
-
-        for &(s, expected) in &cases {
-            assert_tokens(&s, &expected);
-        }
-    }
-
-    #[test]
-    fn test_level_case_insensitive() {
-        let cases = [
-            (Level::Error, [level_token("error")]),
-            (Level::Warn, [level_token("warn")]),
-            (Level::Info, [level_token("info")]),
-            (Level::Debug, [level_token("debug")]),
-            (Level::Trace, [level_token("trace")]),
-        ];
-
-        for &(s, expected) in &cases {
-            assert_de_tokens(&s, &expected);
-        }
-    }
-
-    #[test]
-    fn test_level_de_bytes() {
-        let cases = [
-            (Level::Error, level_bytes_tokens(b"ERROR")),
-            (Level::Warn, level_bytes_tokens(b"WARN")),
-            (Level::Info, level_bytes_tokens(b"INFO")),
-            (Level::Debug, level_bytes_tokens(b"DEBUG")),
-            (Level::Trace, level_bytes_tokens(b"TRACE")),
-        ];
-
-        for &(value, tokens) in &cases {
-            assert_de_tokens(&value, &tokens);
-        }
-    }
-
-    #[test]
-    fn test_level_de_error() {
-        let msg = "unknown variant `errorx`, expected one of \
-                   `ERROR`, `WARN`, `INFO`, `DEBUG`, `TRACE`";
-        assert_de_tokens_error::<Level>(&[level_token("errorx")], msg);
-    }
-
-    #[test]
-    fn test_level_filter_ser_de() {
-        let cases = [
-            (LevelFilter::Off, [level_filter_token("OFF")]),
-            (LevelFilter::Error, [level_filter_token("ERROR")]),
-            (LevelFilter::Warn, [level_filter_token("WARN")]),
-            (LevelFilter::Info, [level_filter_token("INFO")]),
-            (LevelFilter::Debug, [level_filter_token("DEBUG")]),
-            (LevelFilter::Trace, [level_filter_token("TRACE")]),
-        ];
-
-        for &(s, expected) in &cases {
-            assert_tokens(&s, &expected);
-        }
-    }
-
-    #[test]
-    fn test_level_filter_case_insensitive() {
-        let cases = [
-            (LevelFilter::Off, [level_filter_token("off")]),
-            (LevelFilter::Error, [level_filter_token("error")]),
-            (LevelFilter::Warn, [level_filter_token("warn")]),
-            (LevelFilter::Info, [level_filter_token("info")]),
-            (LevelFilter::Debug, [level_filter_token("debug")]),
-            (LevelFilter::Trace, [level_filter_token("trace")]),
-        ];
-
-        for &(s, expected) in &cases {
-            assert_de_tokens(&s, &expected);
-        }
-    }
-
-    #[test]
-    fn test_level_filter_de_bytes() {
-        let cases = [
-            (LevelFilter::Off, level_filter_bytes_tokens(b"OFF")),
-            (LevelFilter::Error, level_filter_bytes_tokens(b"ERROR")),
-            (LevelFilter::Warn, level_filter_bytes_tokens(b"WARN")),
-            (LevelFilter::Info, level_filter_bytes_tokens(b"INFO")),
-            (LevelFilter::Debug, level_filter_bytes_tokens(b"DEBUG")),
-            (LevelFilter::Trace, level_filter_bytes_tokens(b"TRACE")),
-        ];
-
-        for &(value, tokens) in &cases {
-            assert_de_tokens(&value, &tokens);
-        }
-    }
-
-    #[test]
-    fn test_level_filter_de_error() {
-        let msg = "unknown variant `errorx`, expected one of \
-                   `OFF`, `ERROR`, `WARN`, `INFO`, `DEBUG`, `TRACE`";
-        assert_de_tokens_error::<LevelFilter>(&[level_filter_token("errorx")], msg);
-    }
-}
+#![cfg(feature = "serde")]

+

+extern crate serde;

+use self::serde::de::{

+    Deserialize, DeserializeSeed, Deserializer, EnumAccess, Error, Unexpected, VariantAccess,

+    Visitor,

+};

+use self::serde::ser::{Serialize, Serializer};

+

+use {Level, LevelFilter, LOG_LEVEL_NAMES};

+

+use std::fmt;

+use std::str::{self, FromStr};

+

+// The Deserialize impls are handwritten to be case insensitive using FromStr.

+

+impl Serialize for Level {

+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

+    where

+        S: Serializer,

+    {

+        match *self {

+            Level::Error => serializer.serialize_unit_variant("Level", 0, "ERROR"),

+            Level::Warn => serializer.serialize_unit_variant("Level", 1, "WARN"),

+            Level::Info => serializer.serialize_unit_variant("Level", 2, "INFO"),

+            Level::Debug => serializer.serialize_unit_variant("Level", 3, "DEBUG"),

+            Level::Trace => serializer.serialize_unit_variant("Level", 4, "TRACE"),

+        }

+    }

+}

+

+impl<'de> Deserialize<'de> for Level {

+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

+    where

+        D: Deserializer<'de>,

+    {

+        struct LevelIdentifier;

+

+        impl<'de> Visitor<'de> for LevelIdentifier {

+            type Value = Level;

+

+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {

+                formatter.write_str("log level")

+            }

+

+            fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>

+            where

+                E: Error,

+            {

+                // Case insensitive.

+                FromStr::from_str(s).map_err(|_| Error::unknown_variant(s, &LOG_LEVEL_NAMES[1..]))

+            }

+

+            fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>

+            where

+                E: Error,

+            {

+                let variant = str::from_utf8(value)

+                    .map_err(|_| Error::invalid_value(Unexpected::Bytes(value), &self))?;

+

+                self.visit_str(variant)

+            }

+        }

+

+        impl<'de> DeserializeSeed<'de> for LevelIdentifier {

+            type Value = Level;

+

+            fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>

+            where

+                D: Deserializer<'de>,

+            {

+                deserializer.deserialize_identifier(LevelIdentifier)

+            }

+        }

+

+        struct LevelEnum;

+

+        impl<'de> Visitor<'de> for LevelEnum {

+            type Value = Level;

+

+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {

+                formatter.write_str("log level")

+            }

+

+            fn visit_enum<A>(self, value: A) -> Result<Self::Value, A::Error>

+            where

+                A: EnumAccess<'de>,

+            {

+                let (level, variant) = value.variant_seed(LevelIdentifier)?;

+                // Every variant is a unit variant.

+                variant.unit_variant()?;

+                Ok(level)

+            }

+        }

+

+        deserializer.deserialize_enum("Level", &LOG_LEVEL_NAMES[1..], LevelEnum)

+    }

+}

+

+impl Serialize for LevelFilter {

+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

+    where

+        S: Serializer,

+    {

+        match *self {

+            LevelFilter::Off => serializer.serialize_unit_variant("LevelFilter", 0, "OFF"),

+            LevelFilter::Error => serializer.serialize_unit_variant("LevelFilter", 1, "ERROR"),

+            LevelFilter::Warn => serializer.serialize_unit_variant("LevelFilter", 2, "WARN"),

+            LevelFilter::Info => serializer.serialize_unit_variant("LevelFilter", 3, "INFO"),

+            LevelFilter::Debug => serializer.serialize_unit_variant("LevelFilter", 4, "DEBUG"),

+            LevelFilter::Trace => serializer.serialize_unit_variant("LevelFilter", 5, "TRACE"),

+        }

+    }

+}

+

+impl<'de> Deserialize<'de> for LevelFilter {

+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

+    where

+        D: Deserializer<'de>,

+    {

+        struct LevelFilterIdentifier;

+

+        impl<'de> Visitor<'de> for LevelFilterIdentifier {

+            type Value = LevelFilter;

+

+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {

+                formatter.write_str("log level filter")

+            }

+

+            fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>

+            where

+                E: Error,

+            {

+                // Case insensitive.

+                FromStr::from_str(s).map_err(|_| Error::unknown_variant(s, &LOG_LEVEL_NAMES))

+            }

+

+            fn visit_bytes<E>(self, value: &[u8]) -> Result<Self::Value, E>

+            where

+                E: Error,

+            {

+                let variant = str::from_utf8(value)

+                    .map_err(|_| Error::invalid_value(Unexpected::Bytes(value), &self))?;

+

+                self.visit_str(variant)

+            }

+        }

+

+        impl<'de> DeserializeSeed<'de> for LevelFilterIdentifier {

+            type Value = LevelFilter;

+

+            fn deserialize<D>(self, deserializer: D) -> Result<Self::Value, D::Error>

+            where

+                D: Deserializer<'de>,

+            {

+                deserializer.deserialize_identifier(LevelFilterIdentifier)

+            }

+        }

+

+        struct LevelFilterEnum;

+

+        impl<'de> Visitor<'de> for LevelFilterEnum {

+            type Value = LevelFilter;

+

+            fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {

+                formatter.write_str("log level filter")

+            }

+

+            fn visit_enum<A>(self, value: A) -> Result<Self::Value, A::Error>

+            where

+                A: EnumAccess<'de>,

+            {

+                let (level_filter, variant) = value.variant_seed(LevelFilterIdentifier)?;

+                // Every variant is a unit variant.

+                variant.unit_variant()?;

+                Ok(level_filter)

+            }

+        }

+

+        deserializer.deserialize_enum("LevelFilter", &LOG_LEVEL_NAMES, LevelFilterEnum)

+    }

+}

+

+#[cfg(test)]

+mod tests {

+    extern crate serde_test;

+    use self::serde_test::{assert_de_tokens, assert_de_tokens_error, assert_tokens, Token};

+

+    use {Level, LevelFilter};

+

+    fn level_token(variant: &'static str) -> Token {

+        Token::UnitVariant {

+            name: "Level",

+            variant: variant,

+        }

+    }

+

+    fn level_bytes_tokens(variant: &'static [u8]) -> [Token; 3] {

+        [

+            Token::Enum { name: "Level" },

+            Token::Bytes(variant),

+            Token::Unit,

+        ]

+    }

+

+    fn level_filter_token(variant: &'static str) -> Token {

+        Token::UnitVariant {

+            name: "LevelFilter",

+            variant: variant,

+        }

+    }

+

+    fn level_filter_bytes_tokens(variant: &'static [u8]) -> [Token; 3] {

+        [

+            Token::Enum {

+                name: "LevelFilter",

+            },

+            Token::Bytes(variant),

+            Token::Unit,

+        ]

+    }

+

+    #[test]

+    fn test_level_ser_de() {

+        let cases = [

+            (Level::Error, [level_token("ERROR")]),

+            (Level::Warn, [level_token("WARN")]),

+            (Level::Info, [level_token("INFO")]),

+            (Level::Debug, [level_token("DEBUG")]),

+            (Level::Trace, [level_token("TRACE")]),

+        ];

+

+        for &(s, expected) in &cases {

+            assert_tokens(&s, &expected);

+        }

+    }

+

+    #[test]

+    fn test_level_case_insensitive() {

+        let cases = [

+            (Level::Error, [level_token("error")]),

+            (Level::Warn, [level_token("warn")]),

+            (Level::Info, [level_token("info")]),

+            (Level::Debug, [level_token("debug")]),

+            (Level::Trace, [level_token("trace")]),

+        ];

+

+        for &(s, expected) in &cases {

+            assert_de_tokens(&s, &expected);

+        }

+    }

+

+    #[test]

+    fn test_level_de_bytes() {

+        let cases = [

+            (Level::Error, level_bytes_tokens(b"ERROR")),

+            (Level::Warn, level_bytes_tokens(b"WARN")),

+            (Level::Info, level_bytes_tokens(b"INFO")),

+            (Level::Debug, level_bytes_tokens(b"DEBUG")),

+            (Level::Trace, level_bytes_tokens(b"TRACE")),

+        ];

+

+        for &(value, tokens) in &cases {

+            assert_de_tokens(&value, &tokens);

+        }

+    }

+

+    #[test]

+    fn test_level_de_error() {

+        let msg = "unknown variant `errorx`, expected one of \

+                   `ERROR`, `WARN`, `INFO`, `DEBUG`, `TRACE`";

+        assert_de_tokens_error::<Level>(&[level_token("errorx")], msg);

+    }

+

+    #[test]

+    fn test_level_filter_ser_de() {

+        let cases = [

+            (LevelFilter::Off, [level_filter_token("OFF")]),

+            (LevelFilter::Error, [level_filter_token("ERROR")]),

+            (LevelFilter::Warn, [level_filter_token("WARN")]),

+            (LevelFilter::Info, [level_filter_token("INFO")]),

+            (LevelFilter::Debug, [level_filter_token("DEBUG")]),

+            (LevelFilter::Trace, [level_filter_token("TRACE")]),

+        ];

+

+        for &(s, expected) in &cases {

+            assert_tokens(&s, &expected);

+        }

+    }

+

+    #[test]

+    fn test_level_filter_case_insensitive() {

+        let cases = [

+            (LevelFilter::Off, [level_filter_token("off")]),

+            (LevelFilter::Error, [level_filter_token("error")]),

+            (LevelFilter::Warn, [level_filter_token("warn")]),

+            (LevelFilter::Info, [level_filter_token("info")]),

+            (LevelFilter::Debug, [level_filter_token("debug")]),

+            (LevelFilter::Trace, [level_filter_token("trace")]),

+        ];

+

+        for &(s, expected) in &cases {

+            assert_de_tokens(&s, &expected);

+        }

+    }

+

+    #[test]

+    fn test_level_filter_de_bytes() {

+        let cases = [

+            (LevelFilter::Off, level_filter_bytes_tokens(b"OFF")),

+            (LevelFilter::Error, level_filter_bytes_tokens(b"ERROR")),

+            (LevelFilter::Warn, level_filter_bytes_tokens(b"WARN")),

+            (LevelFilter::Info, level_filter_bytes_tokens(b"INFO")),

+            (LevelFilter::Debug, level_filter_bytes_tokens(b"DEBUG")),

+            (LevelFilter::Trace, level_filter_bytes_tokens(b"TRACE")),

+        ];

+

+        for &(value, tokens) in &cases {

+            assert_de_tokens(&value, &tokens);

+        }

+    }

+

+    #[test]

+    fn test_level_filter_de_error() {

+        let msg = "unknown variant `errorx`, expected one of \

+                   `OFF`, `ERROR`, `WARN`, `INFO`, `DEBUG`, `TRACE`";

+        assert_de_tokens_error::<LevelFilter>(&[level_filter_token("errorx")], msg);

+    }

+}

diff --git a/tests/filters.rs b/tests/filters.rs
index e4d21a8..661c034 100644
--- a/tests/filters.rs
+++ b/tests/filters.rs
@@ -1,72 +1,72 @@
-#[macro_use]
-extern crate log;
-
-use log::{Level, LevelFilter, Log, Metadata, Record};
-use std::sync::{Arc, Mutex};
-
-#[cfg(feature = "std")]
-use log::set_boxed_logger;
-
-#[cfg(not(feature = "std"))]
-fn set_boxed_logger(logger: Box<Log>) -> Result<(), log::SetLoggerError> {
-    log::set_logger(unsafe { &*Box::into_raw(logger) })
-}
-
-struct State {
-    last_log: Mutex<Option<Level>>,
-}
-
-struct Logger(Arc<State>);
-
-impl Log for Logger {
-    fn enabled(&self, _: &Metadata) -> bool {
-        true
-    }
-
-    fn log(&self, record: &Record) {
-        *self.0.last_log.lock().unwrap() = Some(record.level());
-    }
-    fn flush(&self) {}
-}
-
-fn main() {
-    let me = Arc::new(State {
-        last_log: Mutex::new(None),
-    });
-    let a = me.clone();
-    set_boxed_logger(Box::new(Logger(me))).unwrap();
-
-    test(&a, LevelFilter::Off);
-    test(&a, LevelFilter::Error);
-    test(&a, LevelFilter::Warn);
-    test(&a, LevelFilter::Info);
-    test(&a, LevelFilter::Debug);
-    test(&a, LevelFilter::Trace);
-}
-
-fn test(a: &State, filter: LevelFilter) {
-    log::set_max_level(filter);
-    error!("");
-    last(&a, t(Level::Error, filter));
-    warn!("");
-    last(&a, t(Level::Warn, filter));
-    info!("");
-    last(&a, t(Level::Info, filter));
-    debug!("");
-    last(&a, t(Level::Debug, filter));
-    trace!("");
-    last(&a, t(Level::Trace, filter));
-
-    fn t(lvl: Level, filter: LevelFilter) -> Option<Level> {
-        if lvl <= filter {
-            Some(lvl)
-        } else {
-            None
-        }
-    }
-}
-
-fn last(state: &State, expected: Option<Level>) {
-    let lvl = state.last_log.lock().unwrap().take();
-    assert_eq!(lvl, expected);
-}
+#[macro_use]

+extern crate log;

+

+use log::{Level, LevelFilter, Log, Metadata, Record};

+use std::sync::{Arc, Mutex};

+

+#[cfg(feature = "std")]

+use log::set_boxed_logger;

+

+#[cfg(not(feature = "std"))]

+fn set_boxed_logger(logger: Box<dyn Log>) -> Result<(), log::SetLoggerError> {

+    log::set_logger(Box::leak(logger))

+}

+

+struct State {

+    last_log: Mutex<Option<Level>>,

+}

+

+struct Logger(Arc<State>);

+

+impl Log for Logger {

+    fn enabled(&self, _: &Metadata) -> bool {

+        true

+    }

+

+    fn log(&self, record: &Record) {

+        *self.0.last_log.lock().unwrap() = Some(record.level());

+    }

+    fn flush(&self) {}

+}

+

+fn main() {

+    let me = Arc::new(State {

+        last_log: Mutex::new(None),

+    });

+    let a = me.clone();

+    set_boxed_logger(Box::new(Logger(me))).unwrap();

+

+    test(&a, LevelFilter::Off);

+    test(&a, LevelFilter::Error);

+    test(&a, LevelFilter::Warn);

+    test(&a, LevelFilter::Info);

+    test(&a, LevelFilter::Debug);

+    test(&a, LevelFilter::Trace);

+}

+

+fn test(a: &State, filter: LevelFilter) {

+    log::set_max_level(filter);

+    error!("");

+    last(&a, t(Level::Error, filter));

+    warn!("");

+    last(&a, t(Level::Warn, filter));

+    info!("");

+    last(&a, t(Level::Info, filter));

+    debug!("");

+    last(&a, t(Level::Debug, filter));

+    trace!("");

+    last(&a, t(Level::Trace, filter));

+

+    fn t(lvl: Level, filter: LevelFilter) -> Option<Level> {

+        if lvl <= filter {

+            Some(lvl)

+        } else {

+            None

+        }

+    }

+}

+

+fn last(state: &State, expected: Option<Level>) {

+    let lvl = state.last_log.lock().unwrap().take();

+    assert_eq!(lvl, expected);

+}

diff --git a/tests/macros.rs b/tests/macros.rs
new file mode 100644
index 0000000..e9dc133
--- /dev/null
+++ b/tests/macros.rs
@@ -0,0 +1,36 @@
+#[macro_use]

+extern crate log;

+

+#[test]

+fn base() {

+    info!("hello");

+    info!("hello",);

+}

+

+#[test]

+fn base_expr_context() {

+    let _ = info!("hello");

+}

+

+#[test]

+fn with_args() {

+    info!("hello {}", "cats");

+    info!("hello {}", "cats",);

+    info!("hello {}", "cats",);

+}

+

+#[test]

+fn with_args_expr_context() {

+    match "cats" {

+        cats => info!("hello {}", cats),

+    };

+}

+

+#[test]

+fn with_named_args() {

+    let cats = "cats";

+

+    info!("hello {cats}", cats = cats);

+    info!("hello {cats}", cats = cats,);

+    info!("hello {cats}", cats = cats,);

+}

diff --git a/triagebot.toml b/triagebot.toml
new file mode 100644
index 0000000..84659a1
--- /dev/null
+++ b/triagebot.toml
@@ -0,0 +1 @@
+[assign]