<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/home/sangenya/.cargo/registry/src/github.com-1ecc6299db9ec823/memoffset-0.6.4/src/lib.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lib.rs - source</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../../ayu.css" disabled ><script id="default-settings"></script><script src="../../storage.js"></script><script src="../../crates.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../../favicon.svg">
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<span class="comment">// Copyright (c) 2017 Gilad Naaman</span>
<span class="comment">//</span>
<span class="comment">// Permission is hereby granted, free of charge, to any person obtaining a copy</span>
<span class="comment">// of this software and associated documentation files (the "Software"), to deal</span>
<span class="comment">// in the Software without restriction, including without limitation the rights</span>
<span class="comment">// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell</span>
<span class="comment">// copies of the Software, and to permit persons to whom the Software is</span>
<span class="comment">// furnished to do so, subject to the following conditions:</span>
<span class="comment">//</span>
<span class="comment">// The above copyright notice and this permission notice shall be included in all</span>
<span class="comment">// copies or substantial portions of the Software.</span>
<span class="comment">//</span>
<span class="comment">// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR</span>
<span class="comment">// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,</span>
<span class="comment">// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE</span>
<span class="comment">// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER</span>
<span class="comment">// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,</span>
<span class="comment">// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE</span>
<span class="comment">// SOFTWARE.</span>
<span class="doccomment">//! A crate used for calculating offsets of struct members and their spans.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This functionality currently can not be used in compile time code such as `const` or `const fn` definitions.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ## Examples</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//! #[macro_use]</span>
<span class="doccomment">//! extern crate memoffset;</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! #[repr(C, packed)]</span>
<span class="doccomment">//! struct HelpMeIAmTrappedInAStructFactory {</span>
<span class="doccomment">//! help_me_before_they_: [u8; 15],</span>
<span class="doccomment">//! a: u32</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! fn main() {</span>
<span class="doccomment">//! assert_eq!(offset_of!(HelpMeIAmTrappedInAStructFactory, a), 15);</span>
<span class="doccomment">//! assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, a), 15..19);</span>
<span class="doccomment">//! assert_eq!(span_of!(HelpMeIAmTrappedInAStructFactory, help_me_before_they_ .. a), 0..15);</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This functionality can be useful, for example, for checksum calculations:</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```ignore</span>
<span class="doccomment">//! #[repr(C, packed)]</span>
<span class="doccomment">//! struct Message {</span>
<span class="doccomment">//! header: MessageHeader,</span>
<span class="doccomment">//! fragment_index: u32,</span>
<span class="doccomment">//! fragment_count: u32,</span>
<span class="doccomment">//! payload: [u8; 1024],</span>
<span class="doccomment">//! checksum: u16</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let checksum_range = &raw[span_of!(Message, header..checksum)];</span>
<span class="doccomment">//! let checksum = crc16(checksum_range);</span>
<span class="doccomment">//! ```</span>
<span class="attribute">#![<span class="ident">no_std</span>]</span>
<span class="attribute">#![<span class="ident">cfg_attr</span>(
<span class="ident">feature</span> <span class="op">=</span> <span class="string">"unstable_const"</span>,
<span class="ident">feature</span>(
<span class="ident">const_ptr_offset_from</span>,
<span class="ident">const_maybe_uninit_as_ptr</span>,
<span class="ident">const_raw_ptr_deref</span>,
<span class="ident">const_refs_to_cell</span>,
)
)]</span>
<span class="attribute">#[<span class="ident">macro_use</span>]</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">doctests</span>)]</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">doctest</span>)]</span>
<span class="kw">extern</span> <span class="kw">crate</span> <span class="ident">doc_comment</span>;
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">doctests</span>)]</span>
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">doctest</span>)]</span>
<span class="macro">doctest!</span>(<span class="string">"../README.md"</span>);
<span class="doccomment">/// Hiden module for things the macros need to access.</span>
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">pub</span> <span class="kw">mod</span> <span class="ident">__priv</span> {
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="ident">core::mem</span>;
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">pub</span> <span class="kw">use</span> <span class="ident">core::ptr</span>;
<span class="doccomment">/// Use type inference to obtain the size of the pointee (without actually using the pointer).</span>
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">size_of_pointee</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">_ptr</span>: <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">T</span>) <span class="op">-</span><span class="op">></span> <span class="ident">usize</span> {
<span class="ident">mem::size_of</span>::<span class="op"><</span><span class="ident">T</span><span class="op">></span>()
}
}
<span class="attribute">#[<span class="ident">macro_use</span>]</span>
<span class="kw">mod</span> <span class="ident">raw_field</span>;
<span class="attribute">#[<span class="ident">macro_use</span>]</span>
<span class="kw">mod</span> <span class="ident">offset_of</span>;
<span class="attribute">#[<span class="ident">macro_use</span>]</span>
<span class="kw">mod</span> <span class="ident">span_of</span>;
</pre></div>
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