| <!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/git/checkouts/rayon-3b3b152053499ede/a07ce2e/src/iter/once.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>once.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="../../../rayon/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="../../../rayon/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">crate</span>::iter::plumbing::<span class="kw-2">*</span>; |
| <span class="kw">use </span><span class="kw">crate</span>::iter::<span class="kw-2">*</span>; |
| |
| <span class="doccomment">/// Creates a parallel iterator that produces an element exactly once. |
| /// |
| /// This admits no parallelism on its own, but it could be chained to existing |
| /// parallel iterators to extend their contents, or otherwise used for any code |
| /// that deals with generic parallel iterators. |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// use rayon::prelude::*; |
| /// use rayon::iter::once; |
| /// |
| /// let pi = (0..1234).into_par_iter() |
| /// .chain(once(-1)) |
| /// .chain(1234..10_000); |
| /// |
| /// assert_eq!(pi.clone().count(), 10_001); |
| /// assert_eq!(pi.clone().filter(|&x| x < 0).count(), 1); |
| /// assert_eq!(pi.position_any(|x| x < 0), Some(1234)); |
| /// ``` |
| </span><span class="kw">pub fn </span>once<T: Send>(item: T) -> Once<T> { |
| Once { item } |
| } |
| |
| <span class="doccomment">/// Iterator adaptor for [the `once()` function](fn.once.html). |
| </span><span class="attribute">#[derive(Clone, Debug)] |
| </span><span class="kw">pub struct </span>Once<T: Send> { |
| item: T, |
| } |
| |
| <span class="kw">impl</span><T: Send> ParallelIterator <span class="kw">for </span>Once<T> { |
| <span class="kw">type </span>Item = T; |
| |
| <span class="kw">fn </span>drive_unindexed<C>(<span class="self">self</span>, consumer: C) -> C::Result |
| <span class="kw">where |
| </span>C: UnindexedConsumer<<span class="self">Self</span>::Item>, |
| { |
| <span class="self">self</span>.drive(consumer) |
| } |
| |
| <span class="kw">fn </span>opt_len(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="prelude-ty">Option</span><usize> { |
| <span class="prelude-val">Some</span>(<span class="number">1</span>) |
| } |
| } |
| |
| <span class="kw">impl</span><T: Send> IndexedParallelIterator <span class="kw">for </span>Once<T> { |
| <span class="kw">fn </span>drive<C>(<span class="self">self</span>, consumer: C) -> C::Result |
| <span class="kw">where |
| </span>C: Consumer<<span class="self">Self</span>::Item>, |
| { |
| consumer.into_folder().consume(<span class="self">self</span>.item).complete() |
| } |
| |
| <span class="kw">fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="number">1 |
| </span>} |
| |
| <span class="kw">fn </span>with_producer<CB>(<span class="self">self</span>, callback: CB) -> CB::Output |
| <span class="kw">where |
| </span>CB: ProducerCallback<<span class="self">Self</span>::Item>, |
| { |
| <span class="comment">// Let `OptionProducer` handle it. |
| </span><span class="prelude-val">Some</span>(<span class="self">self</span>.item).into_par_iter().with_producer(callback) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="rayon" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |