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android / platform / external / rust / crates / synstructure / refs/tags/aml_ads_351017080
tagb54f981050a448db46fe4756fd962437dc7f8a37
taggerThe Android Open Source Project <initial-contribution@android.com>Wed Nov 06 00:15:33 2024 -0800
object96531fed3e51d933f8be912441ea14ccd17d205c 
aml_ads_351017080 (12363824,com.google.android.adservices,com.google.android.go.adservices)
commit96531fed3e51d933f8be912441ea14ccd17d205c[log] [tgz]
authorAndroid Build Coastguard Worker <android-build-coastguard-worker@google.com>Thu Aug 08 01:24:52 2024 +0000
committerAndroid Build Coastguard Worker <android-build-coastguard-worker@google.com>Thu Aug 08 01:24:52 2024 +0000
treec5536c9e149e3f200aa266a0b7ef35ef3f4437e0
parentdd1e73db679ccfbd4d9580e5465428a140ba800a [diff]
parent538d4ce73cece023dc8f4a8118822aac33459a20 [diff]
Snap for 12199826 from 538d4ce73cece023dc8f4a8118822aac33459a20 to mainline-adservices-release

Change-Id: I9ebc70b80cee29187f5671420a4d29f99a20034e
tree: c5536c9e149e3f200aa266a0b7ef35ef3f4437e0
  1. src/
  2. .cargo_vcs_info.json
  3. Android.bp
  4. Cargo.toml
  5. Cargo.toml.orig
  6. cargo2rulesmk.json
  7. cargo_embargo.json
  8. LICENSE
  9. METADATA
  10. MODULE_LICENSE_MIT
  11. OWNERS
  12. README.md
  13. rules.mk
  14. TEST_MAPPING
README.md

synstructure

Latest Version Documentation Build Status Rustc Version 1.31+

NOTE: What follows is an exerpt from the module level documentation. For full details read the docs on docs.rs

This crate provides helper types for matching against enum variants, and extracting bindings to each of the fields in the deriving Struct or Enum in a generic way.

If you are writing a #[derive] which needs to perform some operation on every field, then you have come to the right place!

Example: WalkFields

Trait Implementation

pub trait WalkFields: std::any::Any {
    fn walk_fields(&self, walk: &mut FnMut(&WalkFields));
}
impl WalkFields for i32 {
    fn walk_fields(&self, _walk: &mut FnMut(&WalkFields)) {}
}

Custom Derive

#[macro_use]
extern crate synstructure;
#[macro_use]
extern crate quote;
extern crate proc_macro2;

fn walkfields_derive(s: synstructure::Structure) -> proc_macro2::TokenStream {
    let body = s.each(|bi| quote!{
        walk(#bi)
    });

    s.bound_impl(quote!(example_traits::WalkFields), quote!{
        fn walk_fields(&self, walk: &mut FnMut(&example_traits::WalkFields)) {
            match *self { #body }
        }
    })
}
decl_derive!([WalkFields] => walkfields_derive);

/*
 * Test Case
 */
fn main() {
    test_derive! {
        walkfields_derive {
            enum A<T> {
                B(i32, T),
                C(i32),
            }
        }
        expands to {
            #[allow(non_upper_case_globals)]
            const _DERIVE_example_traits_WalkFields_FOR_A: () = {
                extern crate example_traits;
                impl<T> example_traits::WalkFields for A<T>
                    where T: example_traits::WalkFields
                {
                    fn walk_fields(&self, walk: &mut FnMut(&example_traits::WalkFields)) {
                        match *self {
                            A::B(ref __binding_0, ref __binding_1,) => {
                                { walk(__binding_0) }
                                { walk(__binding_1) }
                            }
                            A::C(ref __binding_0,) => {
                                { walk(__binding_0) }
                            }
                        }
                    }
                }
            };
        }
    }
}

Example: Interest

Trait Implementation

pub trait Interest {
    fn interesting(&self) -> bool;
}
impl Interest for i32 {
    fn interesting(&self) -> bool { *self > 0 }
}

Custom Derive

#[macro_use]
extern crate synstructure;
#[macro_use]
extern crate quote;
extern crate proc_macro2;

fn interest_derive(mut s: synstructure::Structure) -> proc_macro2::TokenStream {
    let body = s.fold(false, |acc, bi| quote!{
        #acc || example_traits::Interest::interesting(#bi)
    });

    s.bound_impl(quote!(example_traits::Interest), quote!{
        fn interesting(&self) -> bool {
            match *self {
                #body
            }
        }
    })
}
decl_derive!([Interest] => interest_derive);

/*
 * Test Case
 */
fn main() {
    test_derive!{
        interest_derive {
            enum A<T> {
                B(i32, T),
                C(i32),
            }
        }
        expands to {
            #[allow(non_upper_case_globals)]
            const _DERIVE_example_traits_Interest_FOR_A: () = {
                extern crate example_traits;
                impl<T> example_traits::Interest for A<T>
                    where T: example_traits::Interest
                {
                    fn interesting(&self) -> bool {
                        match *self {
                            A::B(ref __binding_0, ref __binding_1,) => {
                                false ||
                                    example_traits::Interest::interesting(__binding_0) ||
                                    example_traits::Interest::interesting(__binding_1)
                            }
                            A::C(ref __binding_0,) => {
                                false ||
                                    example_traits::Interest::interesting(__binding_0)
                            }
                        }
                    }
                }
            };
        }
    }
}

For more example usage, consider investigating the abomonation_derive crate, which makes use of this crate, and is fairly simple.