mirror of
https://github.com/openharmony/third_party_rust_memoffset.git
synced 2026-07-18 12:25:36 -04:00
Roland
608e11823e
Remove `const_transmute` feature flag `const_transmute` has been stabilized on current nightly, see https://github.com/rust-lang/rust/pull/72920. Document `const_fn_transmute` requirement when using `offset_of!` inside a `const fn`. Add test for `offset_of!` inside a `const fn`.
93 lines
2.8 KiB
Rust
93 lines
2.8 KiB
Rust
// Copyright (c) 2017 Gilad Naaman
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//
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// Permission is hereby granted, free of charge, to any person obtaining a copy
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// of this software and associated documentation files (the "Software"), to deal
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// in the Software without restriction, including without limitation the rights
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// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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// copies of the Software, and to permit persons to whom the Software is
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// furnished to do so, subject to the following conditions:
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//
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// The above copyright notice and this permission notice shall be included in all
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// copies or substantial portions of the Software.
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//
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// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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// SOFTWARE.
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//! A crate used for calculating offsets of struct members and their spans.
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//!
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//! This functionality currently can not be used in compile time code such as `const` or `const fn` definitions.
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//!
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//! ## Examples
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//! ```
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//! #[macro_use]
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//! extern crate memoffset;
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//!
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//! #[repr(C, packed)]
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//! struct HelpMeIAmTrappedInAStructFactory {
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//! help_me_before_they_: [u8; 15],
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//! a: u32
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//! }
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//!
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//! fn main() {
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//! assert_eq!(offset_of!(HelpMeIAmTrappedInAStructFactory, a), 15);
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//! assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, a), 15..19);
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//! assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, help_me_before_they_ .. a), 0..15);
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//! }
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//! ```
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//!
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//! This functionality can be useful, for example, for checksum calculations:
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//!
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//! ```ignore
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//! #[repr(C, packed)]
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//! struct Message {
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//! header: MessageHeader,
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//! fragment_index: u32,
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//! fragment_count: u32,
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//! payload: [u8; 1024],
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//! checksum: u16
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//! }
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//!
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//! let checksum_range = &raw[span_of!(Message, header..checksum)];
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//! let checksum = crc16(checksum_range);
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//! ```
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#![no_std]
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#![cfg_attr(
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feature = "unstable_const",
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feature(
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ptr_offset_from,
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const_fn,
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const_fn_transmute,
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const_ptr_offset_from,
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const_raw_ptr_deref,
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)
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)]
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#![cfg_attr(feature = "unstable_raw", feature(raw_ref_macros))]
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#[macro_use]
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#[cfg(doctests)]
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#[cfg(doctest)]
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extern crate doc_comment;
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#[cfg(doctests)]
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#[cfg(doctest)]
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doctest!("../README.md");
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// This `use` statement enables the macros to use `$crate::mem`.
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// Doing this enables this crate to function under both std and no-std crates.
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#[doc(hidden)]
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pub use core::mem;
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#[doc(hidden)]
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pub use core::ptr;
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#[macro_use]
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mod raw_field;
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#[macro_use]
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mod offset_of;
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#[macro_use]
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mod span_of;
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