| <!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/tokio-377c595163f99a10/dfe252d/tokio/src/io/util/fill_buf.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>fill_buf.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="../../../../tokio/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="../../../../tokio/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> |
| <span id="2">2</span> |
| <span id="3">3</span> |
| <span id="4">4</span> |
| <span id="5">5</span> |
| <span id="6">6</span> |
| <span id="7">7</span> |
| <span id="8">8</span> |
| <span id="9">9</span> |
| <span id="10">10</span> |
| <span id="11">11</span> |
| <span id="12">12</span> |
| <span id="13">13</span> |
| <span id="14">14</span> |
| <span id="15">15</span> |
| <span id="16">16</span> |
| <span id="17">17</span> |
| <span id="18">18</span> |
| <span id="19">19</span> |
| <span id="20">20</span> |
| <span id="21">21</span> |
| <span id="22">22</span> |
| <span id="23">23</span> |
| <span id="24">24</span> |
| <span id="25">25</span> |
| <span id="26">26</span> |
| <span id="27">27</span> |
| <span id="28">28</span> |
| <span id="29">29</span> |
| <span id="30">30</span> |
| <span id="31">31</span> |
| <span id="32">32</span> |
| <span id="33">33</span> |
| <span id="34">34</span> |
| <span id="35">35</span> |
| <span id="36">36</span> |
| <span id="37">37</span> |
| <span id="38">38</span> |
| <span id="39">39</span> |
| <span id="40">40</span> |
| <span id="41">41</span> |
| <span id="42">42</span> |
| <span id="43">43</span> |
| <span id="44">44</span> |
| <span id="45">45</span> |
| <span id="46">46</span> |
| <span id="47">47</span> |
| <span id="48">48</span> |
| <span id="49">49</span> |
| <span id="50">50</span> |
| <span id="51">51</span> |
| <span id="52">52</span> |
| <span id="53">53</span> |
| <span id="54">54</span> |
| <span id="55">55</span> |
| <span id="56">56</span> |
| <span id="57">57</span> |
| <span id="58">58</span> |
| <span id="59">59</span> |
| </pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::io::AsyncBufRead; |
| |
| <span class="kw">use </span>pin_project_lite::pin_project; |
| <span class="kw">use </span>std::future::Future; |
| <span class="kw">use </span>std::io; |
| <span class="kw">use </span>std::marker::PhantomPinned; |
| <span class="kw">use </span>std::pin::Pin; |
| <span class="kw">use </span>std::task::{Context, Poll}; |
| |
| <span class="macro">pin_project! </span>{ |
| <span class="doccomment">/// Future for the [`fill_buf`](crate::io::AsyncBufReadExt::fill_buf) method. |
| </span><span class="attribute">#[derive(Debug)] |
| #[must_use = <span class="string">"futures do nothing unless you `.await` or poll them"</span>] |
| </span><span class="kw">pub struct </span>FillBuf<<span class="lifetime">'a</span>, R: <span class="question-mark">?</span>Sized> { |
| reader: <span class="prelude-ty">Option</span><<span class="kw-2">&</span><span class="lifetime">'a </span><span class="kw-2">mut </span>R>, |
| <span class="attribute">#[pin] |
| </span>_pin: PhantomPinned, |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>fill_buf<R>(reader: <span class="kw-2">&mut </span>R) -> FillBuf<<span class="lifetime">'_</span>, R> |
| <span class="kw">where |
| </span>R: AsyncBufRead + <span class="question-mark">?</span>Sized + Unpin, |
| { |
| FillBuf { |
| reader: <span class="prelude-val">Some</span>(reader), |
| _pin: PhantomPinned, |
| } |
| } |
| |
| <span class="kw">impl</span><<span class="lifetime">'a</span>, R: AsyncBufRead + <span class="question-mark">?</span>Sized + Unpin> Future <span class="kw">for </span>FillBuf<<span class="lifetime">'a</span>, R> { |
| <span class="kw">type </span>Output = io::Result<<span class="kw-2">&</span><span class="lifetime">'a </span>[u8]>; |
| |
| <span class="kw">fn </span>poll(<span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">let </span>me = <span class="self">self</span>.project(); |
| |
| <span class="kw">let </span>reader = me.reader.take().expect(<span class="string">"Polled after completion."</span>); |
| <span class="kw">match </span>Pin::new(<span class="kw-2">&mut *</span>reader).poll_fill_buf(cx) { |
| Poll::Ready(<span class="prelude-val">Ok</span>(slice)) => <span class="kw">unsafe </span>{ |
| <span class="comment">// Safety: This is necessary only due to a limitation in the |
| // borrow checker. Once Rust starts using the polonius borrow |
| // checker, this can be simplified. |
| // |
| // The safety of this transmute relies on the fact that the |
| // value of `reader` is `None` when we return in this branch. |
| // Otherwise the caller could poll us again after |
| // completion, and access the mutable reference while the |
| // returned immutable reference still exists. |
| </span><span class="kw">let </span>slice = std::mem::transmute::<<span class="kw-2">&</span>[u8], <span class="kw-2">&</span><span class="lifetime">'a </span>[u8]>(slice); |
| Poll::Ready(<span class="prelude-val">Ok</span>(slice)) |
| }, |
| Poll::Ready(<span class="prelude-val">Err</span>(err)) => Poll::Ready(<span class="prelude-val">Err</span>(err)), |
| Poll::Pending => { |
| <span class="kw-2">*</span>me.reader = <span class="prelude-val">Some</span>(reader); |
| Poll::Pending |
| } |
| } |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../../" data-current-crate="tokio" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
