| // Copyright (c) 2017 Gilad Naaman |
| // |
| // 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. |
| |
| //! A crate used for calculating offsets of struct members and their spans. |
| //! |
| //! This functionality currently can not be used in compile time code such as `const` or `const fn` definitions. |
| //! |
| //! ## Examples |
| //! ``` |
| //! use memoffset::{offset_of, span_of}; |
| //! |
| //! #[repr(C, packed)] |
| //! struct HelpMeIAmTrappedInAStructFactory { |
| //! help_me_before_they_: [u8; 15], |
| //! a: u32 |
| //! } |
| //! |
| //! fn main() { |
| //! assert_eq!(offset_of!(HelpMeIAmTrappedInAStructFactory, a), 15); |
| //! assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, a), 15..19); |
| //! assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, help_me_before_they_ .. a), 0..15); |
| //! } |
| //! ``` |
| //! |
| //! This functionality can be useful, for example, for checksum calculations: |
| //! |
| //! ```ignore |
| //! #[repr(C, packed)] |
| //! struct Message { |
| //! header: MessageHeader, |
| //! fragment_index: u32, |
| //! fragment_count: u32, |
| //! payload: [u8; 1024], |
| //! checksum: u16 |
| //! } |
| //! |
| //! let checksum_range = &raw[span_of!(Message, header..checksum)]; |
| //! let checksum = crc16(checksum_range); |
| //! ``` |
| |
| // ANDROID: include standard library to build as a dylib |
| //#![no_std] |
| #![cfg_attr( |
| all(feature = "unstable_const", not(stable_const)), |
| feature(const_ptr_offset_from) |
| )] |
| #![cfg_attr(feature = "unstable_const", feature(const_refs_to_cell))] |
| #![cfg_attr(feature = "unstable_offset_of", feature(allow_internal_unstable))] |
| |
| #[macro_use] |
| #[cfg(doctests)] |
| #[cfg(doctest)] |
| extern crate doc_comment; |
| #[cfg(doctests)] |
| #[cfg(doctest)] |
| doctest!("../README.md"); |
| |
| /// Hidden module for things the macros need to access. |
| #[doc(hidden)] |
| pub mod __priv { |
| #[doc(hidden)] |
| pub use std::mem; // ANDROID: use std instead of core, since we're not building with no-std. |
| #[doc(hidden)] |
| pub use std::ptr; // ANDROID: use std instead of core, since we're not building with no-std. |
| |
| /// Use type inference to obtain the size of the pointee (without actually using the pointer). |
| #[doc(hidden)] |
| pub fn size_of_pointee<T>(_ptr: *const T) -> usize { |
| mem::size_of::<T>() |
| } |
| } |
| |
| #[macro_use] |
| mod raw_field; |
| #[macro_use] |
| mod offset_of; |
| #[macro_use] |
| mod span_of; |