| <!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 `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/hashbrown-0.12.3/src/raw/bitmask.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>bitmask.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../hashbrown/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../hashbrown/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">super</span>::imp::{BitMaskWord, BITMASK_MASK, BITMASK_STRIDE}; |
| <span class="attribute">#[cfg(feature = <span class="string">"nightly"</span>)] |
| </span><span class="kw">use </span>core::intrinsics; |
| |
| <span class="doccomment">/// A bit mask which contains the result of a `Match` operation on a `Group` and |
| /// allows iterating through them. |
| /// |
| /// The bit mask is arranged so that low-order bits represent lower memory |
| /// addresses for group match results. |
| /// |
| /// For implementation reasons, the bits in the set may be sparsely packed, so |
| /// that there is only one bit-per-byte used (the high bit, 7). If this is the |
| /// case, `BITMASK_STRIDE` will be 8 to indicate a divide-by-8 should be |
| /// performed on counts/indices to normalize this difference. `BITMASK_MASK` is |
| /// similarly a mask of all the actually-used bits. |
| </span><span class="attribute">#[derive(Copy, Clone)] |
| </span><span class="kw">pub struct </span>BitMask(<span class="kw">pub </span>BitMaskWord); |
| |
| <span class="attribute">#[allow(clippy::use_self)] |
| </span><span class="kw">impl </span>BitMask { |
| <span class="doccomment">/// Returns a new `BitMask` with all bits inverted. |
| </span><span class="attribute">#[inline] |
| #[must_use] |
| </span><span class="kw">pub fn </span>invert(<span class="self">self</span>) -> <span class="self">Self </span>{ |
| BitMask(<span class="self">self</span>.<span class="number">0 </span>^ BITMASK_MASK) |
| } |
| |
| <span class="doccomment">/// Flip the bit in the mask for the entry at the given index. |
| /// |
| /// Returns the bit's previous state. |
| </span><span class="attribute">#[inline] |
| #[allow(clippy::cast_ptr_alignment)] |
| #[cfg(feature = <span class="string">"raw"</span>)] |
| </span><span class="kw">pub unsafe fn </span>flip(<span class="kw-2">&mut </span><span class="self">self</span>, index: usize) -> bool { |
| <span class="comment">// NOTE: The + BITMASK_STRIDE - 1 is to set the high bit. |
| </span><span class="kw">let </span>mask = <span class="number">1 </span><< (index * BITMASK_STRIDE + BITMASK_STRIDE - <span class="number">1</span>); |
| <span class="self">self</span>.<span class="number">0 </span>^= mask; |
| <span class="comment">// The bit was set if the bit is now 0. |
| </span><span class="self">self</span>.<span class="number">0 </span>& mask == <span class="number">0 |
| </span>} |
| |
| <span class="doccomment">/// Returns a new `BitMask` with the lowest bit removed. |
| </span><span class="attribute">#[inline] |
| #[must_use] |
| </span><span class="kw">pub fn </span>remove_lowest_bit(<span class="self">self</span>) -> <span class="self">Self </span>{ |
| BitMask(<span class="self">self</span>.<span class="number">0 </span>& (<span class="self">self</span>.<span class="number">0 </span>- <span class="number">1</span>)) |
| } |
| <span class="doccomment">/// Returns whether the `BitMask` has at least one set bit. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>any_bit_set(<span class="self">self</span>) -> bool { |
| <span class="self">self</span>.<span class="number">0 </span>!= <span class="number">0 |
| </span>} |
| |
| <span class="doccomment">/// Returns the first set bit in the `BitMask`, if there is one. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>lowest_set_bit(<span class="self">self</span>) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">if </span><span class="self">self</span>.<span class="number">0 </span>== <span class="number">0 </span>{ |
| <span class="prelude-val">None |
| </span>} <span class="kw">else </span>{ |
| <span class="prelude-val">Some</span>(<span class="kw">unsafe </span>{ <span class="self">self</span>.lowest_set_bit_nonzero() }) |
| } |
| } |
| |
| <span class="doccomment">/// Returns the first set bit in the `BitMask`, if there is one. The |
| /// bitmask must not be empty. |
| </span><span class="attribute">#[inline] |
| #[cfg(feature = <span class="string">"nightly"</span>)] |
| </span><span class="kw">pub unsafe fn </span>lowest_set_bit_nonzero(<span class="self">self</span>) -> usize { |
| intrinsics::cttz_nonzero(<span class="self">self</span>.<span class="number">0</span>) <span class="kw">as </span>usize / BITMASK_STRIDE |
| } |
| <span class="attribute">#[inline] |
| #[cfg(not(feature = <span class="string">"nightly"</span>))] |
| </span><span class="kw">pub unsafe fn </span>lowest_set_bit_nonzero(<span class="self">self</span>) -> usize { |
| <span class="self">self</span>.trailing_zeros() |
| } |
| |
| <span class="doccomment">/// Returns the number of trailing zeroes in the `BitMask`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>trailing_zeros(<span class="self">self</span>) -> usize { |
| <span class="comment">// ARM doesn't have a trailing_zeroes instruction, and instead uses |
| // reverse_bits (RBIT) + leading_zeroes (CLZ). However older ARM |
| // versions (pre-ARMv7) don't have RBIT and need to emulate it |
| // instead. Since we only have 1 bit set in each byte on ARM, we can |
| // use swap_bytes (REV) + leading_zeroes instead. |
| </span><span class="kw">if </span><span class="macro">cfg!</span>(target_arch = <span class="string">"arm"</span>) && BITMASK_STRIDE % <span class="number">8 </span>== <span class="number">0 </span>{ |
| <span class="self">self</span>.<span class="number">0</span>.swap_bytes().leading_zeros() <span class="kw">as </span>usize / BITMASK_STRIDE |
| } <span class="kw">else </span>{ |
| <span class="self">self</span>.<span class="number">0</span>.trailing_zeros() <span class="kw">as </span>usize / BITMASK_STRIDE |
| } |
| } |
| |
| <span class="doccomment">/// Returns the number of leading zeroes in the `BitMask`. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub fn </span>leading_zeros(<span class="self">self</span>) -> usize { |
| <span class="self">self</span>.<span class="number">0</span>.leading_zeros() <span class="kw">as </span>usize / BITMASK_STRIDE |
| } |
| } |
| |
| <span class="kw">impl </span>IntoIterator <span class="kw">for </span>BitMask { |
| <span class="kw">type </span>Item = usize; |
| <span class="kw">type </span>IntoIter = BitMaskIter; |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>into_iter(<span class="self">self</span>) -> BitMaskIter { |
| BitMaskIter(<span class="self">self</span>) |
| } |
| } |
| |
| <span class="doccomment">/// Iterator over the contents of a `BitMask`, returning the indices of set |
| /// bits. |
| </span><span class="kw">pub struct </span>BitMaskIter(BitMask); |
| |
| <span class="kw">impl </span>Iterator <span class="kw">for </span>BitMaskIter { |
| <span class="kw">type </span>Item = usize; |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>next(<span class="kw-2">&mut </span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="kw">let </span>bit = <span class="self">self</span>.<span class="number">0</span>.lowest_set_bit()<span class="question-mark">?</span>; |
| <span class="self">self</span>.<span class="number">0 </span>= <span class="self">self</span>.<span class="number">0</span>.remove_lowest_bit(); |
| <span class="prelude-val">Some</span>(bit) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="hashbrown" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |