<!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/rayon-1.5.1/src/iter/once.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>once.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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</pre><pre class="rust">
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::iter::plumbing</span>::<span class="kw-2">*</span>;
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::iter</span>::<span class="kw-2">*</span>;
<span class="doccomment">/// Creates a parallel iterator that produces an element exactly once.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This admits no parallelism on its own, but it could be chained to existing</span>
<span class="doccomment">/// parallel iterators to extend their contents, or otherwise used for any code</span>
<span class="doccomment">/// that deals with generic parallel iterators.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use rayon::prelude::*;</span>
<span class="doccomment">/// use rayon::iter::once;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let pi = (0..1234).into_par_iter()</span>
<span class="doccomment">/// .chain(once(-1))</span>
<span class="doccomment">/// .chain(1234..10_000);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// assert_eq!(pi.clone().count(), 10_001);</span>
<span class="doccomment">/// assert_eq!(pi.clone().filter(|&x| x < 0).count(), 1);</span>
<span class="doccomment">/// assert_eq!(pi.position_any(|x| x < 0), Some(1234));</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">once</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span>(<span class="ident">item</span>: <span class="ident">T</span>) <span class="op">-</span><span class="op">></span> <span class="ident">Once</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Once</span> { <span class="ident">item</span> }
}
<span class="doccomment">/// Iterator adaptor for [the `once()` function](fn.once.html).</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Once</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span> {
<span class="ident">item</span>: <span class="ident">T</span>,
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span> <span class="ident">ParallelIterator</span> <span class="kw">for</span> <span class="ident">Once</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">fn</span> <span class="ident">drive_unindexed</span><span class="op"><</span><span class="ident">C</span><span class="op">></span>(<span class="self">self</span>, <span class="ident">consumer</span>: <span class="ident">C</span>) <span class="op">-</span><span class="op">></span> <span class="ident">C::Result</span>
<span class="kw">where</span>
<span class="ident">C</span>: <span class="ident">UnindexedConsumer</span><span class="op"><</span><span class="self">Self</span><span class="ident">::Item</span><span class="op">></span>,
{
<span class="self">self</span>.<span class="ident">drive</span>(<span class="ident">consumer</span>)
}
<span class="kw">fn</span> <span class="ident">opt_len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span> {
<span class="prelude-val">Some</span>(<span class="number">1</span>)
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span> <span class="ident">IndexedParallelIterator</span> <span class="kw">for</span> <span class="ident">Once</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">drive</span><span class="op"><</span><span class="ident">C</span><span class="op">></span>(<span class="self">self</span>, <span class="ident">consumer</span>: <span class="ident">C</span>) <span class="op">-</span><span class="op">></span> <span class="ident">C::Result</span>
<span class="kw">where</span>
<span class="ident">C</span>: <span class="ident">Consumer</span><span class="op"><</span><span class="self">Self</span><span class="ident">::Item</span><span class="op">></span>,
{
<span class="ident">consumer</span>.<span class="ident">into_folder</span>().<span class="ident">consume</span>(<span class="self">self</span>.<span class="ident">item</span>).<span class="ident">complete</span>()
}
<span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">usize</span> {
<span class="number">1</span>
}
<span class="kw">fn</span> <span class="ident">with_producer</span><span class="op"><</span><span class="ident">CB</span><span class="op">></span>(<span class="self">self</span>, <span class="ident">callback</span>: <span class="ident">CB</span>) <span class="op">-</span><span class="op">></span> <span class="ident">CB::Output</span>
<span class="kw">where</span>
<span class="ident">CB</span>: <span class="ident">ProducerCallback</span><span class="op"><</span><span class="self">Self</span><span class="ident">::Item</span><span class="op">></span>,
{
<span class="comment">// Let `OptionProducer` handle it.</span>
<span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">item</span>).<span class="ident">into_par_iter</span>().<span class="ident">with_producer</span>(<span class="ident">callback</span>)
}
}
</pre></div>
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