| <!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/fold_chunks.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>fold_chunks.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>std::fmt::{<span class="self">self</span>, Debug}; |
| |
| <span class="kw">use </span><span class="kw">super</span>::chunks::ChunkProducer; |
| <span class="kw">use </span><span class="kw">super</span>::plumbing::<span class="kw-2">*</span>; |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| <span class="kw">use </span><span class="kw">crate</span>::math::div_round_up; |
| |
| <span class="doccomment">/// `FoldChunks` is an iterator that groups elements of an underlying iterator and applies a |
| /// function over them, producing a single value for each group. |
| /// |
| /// This struct is created by the [`fold_chunks()`] method on [`IndexedParallelIterator`] |
| /// |
| /// [`fold_chunks()`]: trait.IndexedParallelIterator.html#method.fold_chunks |
| /// [`IndexedParallelIterator`]: trait.IndexedParallelIterator.html |
| </span><span class="attribute">#[must_use = <span class="string">"iterator adaptors are lazy and do nothing unless consumed"</span>] |
| #[derive(Clone)] |
| </span><span class="kw">pub struct </span>FoldChunks<I, ID, F> |
| <span class="kw">where |
| </span>I: IndexedParallelIterator, |
| { |
| base: I, |
| chunk_size: usize, |
| fold_op: F, |
| identity: ID, |
| } |
| |
| <span class="kw">impl</span><I: IndexedParallelIterator + Debug, ID, F> Debug <span class="kw">for </span>FoldChunks<I, ID, F> { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| f.debug_struct(<span class="string">"Fold"</span>) |
| .field(<span class="string">"base"</span>, <span class="kw-2">&</span><span class="self">self</span>.base) |
| .field(<span class="string">"chunk_size"</span>, <span class="kw-2">&</span><span class="self">self</span>.chunk_size) |
| .finish() |
| } |
| } |
| |
| <span class="kw">impl</span><I, ID, U, F> FoldChunks<I, ID, F> |
| <span class="kw">where |
| </span>I: IndexedParallelIterator, |
| ID: Fn() -> U + Send + Sync, |
| F: Fn(U, I::Item) -> U + Send + Sync, |
| U: Send, |
| { |
| <span class="doccomment">/// Creates a new `FoldChunks` iterator |
| </span><span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>new(base: I, chunk_size: usize, identity: ID, fold_op: F) -> <span class="self">Self </span>{ |
| FoldChunks { |
| base, |
| chunk_size, |
| identity, |
| fold_op, |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><I, ID, U, F> ParallelIterator <span class="kw">for </span>FoldChunks<I, ID, F> |
| <span class="kw">where |
| </span>I: IndexedParallelIterator, |
| ID: Fn() -> U + Send + Sync, |
| F: Fn(U, I::Item) -> U + Send + Sync, |
| U: Send, |
| { |
| <span class="kw">type </span>Item = U; |
| |
| <span class="kw">fn </span>drive_unindexed<C>(<span class="self">self</span>, consumer: C) -> C::Result |
| <span class="kw">where |
| </span>C: Consumer<U>, |
| { |
| bridge(<span class="self">self</span>, 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="self">self</span>.len()) |
| } |
| } |
| |
| <span class="kw">impl</span><I, ID, U, F> IndexedParallelIterator <span class="kw">for </span>FoldChunks<I, ID, F> |
| <span class="kw">where |
| </span>I: IndexedParallelIterator, |
| ID: Fn() -> U + Send + Sync, |
| F: Fn(U, I::Item) -> U + Send + Sync, |
| U: Send, |
| { |
| <span class="kw">fn </span>len(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| div_round_up(<span class="self">self</span>.base.len(), <span class="self">self</span>.chunk_size) |
| } |
| |
| <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>, |
| { |
| bridge(<span class="self">self</span>, consumer) |
| } |
| |
| <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="kw">let </span>len = <span class="self">self</span>.base.len(); |
| <span class="kw">return </span><span class="self">self</span>.base.with_producer(Callback { |
| chunk_size: <span class="self">self</span>.chunk_size, |
| len, |
| identity: <span class="self">self</span>.identity, |
| fold_op: <span class="self">self</span>.fold_op, |
| callback, |
| }); |
| |
| <span class="kw">struct </span>Callback<CB, ID, F> { |
| chunk_size: usize, |
| len: usize, |
| identity: ID, |
| fold_op: F, |
| callback: CB, |
| } |
| |
| <span class="kw">impl</span><T, CB, ID, U, F> ProducerCallback<T> <span class="kw">for </span>Callback<CB, ID, F> |
| <span class="kw">where |
| </span>CB: ProducerCallback<U>, |
| ID: Fn() -> U + Send + Sync, |
| F: Fn(U, T) -> U + Send + Sync, |
| { |
| <span class="kw">type </span>Output = CB::Output; |
| |
| <span class="kw">fn </span>callback<P>(<span class="self">self</span>, base: P) -> CB::Output |
| <span class="kw">where |
| </span>P: Producer<Item = T>, |
| { |
| <span class="kw">let </span>identity = <span class="kw-2">&</span><span class="self">self</span>.identity; |
| <span class="kw">let </span>fold_op = <span class="kw-2">&</span><span class="self">self</span>.fold_op; |
| <span class="kw">let </span>fold_iter = <span class="kw">move </span>|iter: P::IntoIter| iter.fold(identity(), fold_op); |
| <span class="kw">let </span>producer = ChunkProducer::new(<span class="self">self</span>.chunk_size, <span class="self">self</span>.len, base, fold_iter); |
| <span class="self">self</span>.callback.callback(producer) |
| } |
| } |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>test { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| <span class="kw">use </span>std::ops::Add; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>check_fold_chunks() { |
| <span class="kw">let </span>words = <span class="string">"bishbashbosh!" |
| </span>.chars() |
| .collect::<Vec<<span class="kw">_</span>>>() |
| .into_par_iter() |
| .fold_chunks(<span class="number">4</span>, String::new, |<span class="kw-2">mut </span>s, c| { |
| s.push(c); |
| s |
| }) |
| .collect::<Vec<<span class="kw">_</span>>>(); |
| |
| <span class="macro">assert_eq!</span>(words, <span class="macro">vec!</span>[<span class="string">"bish"</span>, <span class="string">"bash"</span>, <span class="string">"bosh"</span>, <span class="string">"!"</span>]); |
| } |
| |
| <span class="comment">// 'closure' values for tests below |
| </span><span class="kw">fn </span>id() -> i32 { |
| <span class="number">0 |
| </span>} |
| <span class="kw">fn </span>sum<T, U>(x: T, y: U) -> T |
| <span class="kw">where |
| </span>T: Add<U, Output = T>, |
| { |
| x + y |
| } |
| |
| <span class="attribute">#[test] |
| #[should_panic(expected = <span class="string">"chunk_size must not be zero"</span>)] |
| </span><span class="kw">fn </span>check_fold_chunks_zero_size() { |
| <span class="kw">let _</span>: Vec<i32> = <span class="macro">vec!</span>[<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>] |
| .into_par_iter() |
| .fold_chunks(<span class="number">0</span>, id, sum) |
| .collect(); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>check_fold_chunks_even_size() { |
| <span class="macro">assert_eq!</span>( |
| <span class="macro">vec!</span>[<span class="number">1 </span>+ <span class="number">2 </span>+ <span class="number">3</span>, <span class="number">4 </span>+ <span class="number">5 </span>+ <span class="number">6</span>, <span class="number">7 </span>+ <span class="number">8 </span>+ <span class="number">9</span>], |
| (<span class="number">1</span>..<span class="number">10</span>) |
| .into_par_iter() |
| .fold_chunks(<span class="number">3</span>, id, sum) |
| .collect::<Vec<i32>>() |
| ); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>check_fold_chunks_empty() { |
| <span class="kw">let </span>v: Vec<i32> = <span class="macro">vec!</span>[]; |
| <span class="kw">let </span>expected: Vec<i32> = <span class="macro">vec!</span>[]; |
| <span class="macro">assert_eq!</span>( |
| expected, |
| v.into_par_iter() |
| .fold_chunks(<span class="number">2</span>, id, sum) |
| .collect::<Vec<i32>>() |
| ); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>check_fold_chunks_len() { |
| <span class="macro">assert_eq!</span>(<span class="number">4</span>, (<span class="number">0</span>..<span class="number">8</span>).into_par_iter().fold_chunks(<span class="number">2</span>, id, sum).len()); |
| <span class="macro">assert_eq!</span>(<span class="number">3</span>, (<span class="number">0</span>..<span class="number">9</span>).into_par_iter().fold_chunks(<span class="number">3</span>, id, sum).len()); |
| <span class="macro">assert_eq!</span>(<span class="number">3</span>, (<span class="number">0</span>..<span class="number">8</span>).into_par_iter().fold_chunks(<span class="number">3</span>, id, sum).len()); |
| <span class="macro">assert_eq!</span>(<span class="number">1</span>, (<span class="kw-2">&</span>[<span class="number">1</span>]).par_iter().fold_chunks(<span class="number">3</span>, id, sum).len()); |
| <span class="macro">assert_eq!</span>(<span class="number">0</span>, (<span class="number">0</span>..<span class="number">0</span>).into_par_iter().fold_chunks(<span class="number">3</span>, id, sum).len()); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>check_fold_chunks_uneven() { |
| <span class="kw">let </span>cases: Vec<(Vec<u32>, usize, Vec<u32>)> = <span class="macro">vec!</span>[ |
| ((<span class="number">0</span>..<span class="number">5</span>).collect(), <span class="number">3</span>, <span class="macro">vec!</span>[<span class="number">0 </span>+ <span class="number">1 </span>+ <span class="number">2</span>, <span class="number">3 </span>+ <span class="number">4</span>]), |
| (<span class="macro">vec!</span>[<span class="number">1</span>], <span class="number">5</span>, <span class="macro">vec!</span>[<span class="number">1</span>]), |
| ((<span class="number">0</span>..<span class="number">4</span>).collect(), <span class="number">3</span>, <span class="macro">vec!</span>[<span class="number">0 </span>+ <span class="number">1 </span>+ <span class="number">2</span>, <span class="number">3</span>]), |
| ]; |
| |
| <span class="kw">for </span>(i, (v, n, expected)) <span class="kw">in </span>cases.into_iter().enumerate() { |
| <span class="kw">let </span><span class="kw-2">mut </span>res: Vec<u32> = <span class="macro">vec!</span>[]; |
| v.par_iter() |
| .fold_chunks(n, || <span class="number">0</span>, sum) |
| .collect_into_vec(<span class="kw-2">&mut </span>res); |
| <span class="macro">assert_eq!</span>(expected, res, <span class="string">"Case {} failed"</span>, i); |
| |
| res.truncate(<span class="number">0</span>); |
| v.into_par_iter() |
| .fold_chunks(n, || <span class="number">0</span>, sum) |
| .rev() |
| .collect_into_vec(<span class="kw-2">&mut </span>res); |
| <span class="macro">assert_eq!</span>( |
| expected.into_iter().rev().collect::<Vec<u32>>(), |
| res, |
| <span class="string">"Case {} reversed failed"</span>, |
| i |
| ); |
| } |
| } |
| } |
| </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> |
