| <!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="An extension trait which adds utility methods to `AsyncRead` types."><meta name="keywords" content="rust, rustlang, rust-lang, AsyncReadExt"><title>AsyncReadExt in futures::io - Rust</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="sidebar-items.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 trait"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="mobile-topbar"><button class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../../futures/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../futures/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2 class="location"><a href="#">AsyncReadExt</a></h2><div class="sidebar-elems"><section><h3><a href="#provided-methods">Provided Methods</a></h3><ul class="block"><li><a href="#method.chain">chain</a></li><li><a href="#method.read">read</a></li><li><a href="#method.read_exact">read_exact</a></li><li><a href="#method.read_to_end">read_to_end</a></li><li><a href="#method.read_to_string">read_to_string</a></li><li><a href="#method.read_vectored">read_vectored</a></li><li><a href="#method.split">split</a></li><li><a href="#method.take">take</a></li></ul><h3><a href="#implementors">Implementors</a></h3></section><h2><a href="index.html">In futures::io</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><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="main-heading"><h1 class="fqn">Trait <a href="../index.html">futures</a>::<wbr><a href="index.html">io</a>::<wbr><a class="trait" href="#">AsyncReadExt</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../../src/futures_util/io/mod.rs.html#148">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><pre class="rust trait"><code>pub trait AsyncReadExt: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> { |
| fn <a href="#method.chain" class="fnname">chain</a><R>(self, next: R) -> <a class="struct" href="struct.Chain.html" title="struct futures::io::Chain">Chain</a><Self, R><br> <span class="where">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a></span>, |
| { ... } |
| <span class="item-spacer"></span> fn <a href="#method.read" class="fnname">read</a>(&'a mut self, buf: &'a mut [<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]) -> <a class="struct" href="struct.Read.html" title="struct futures::io::Read">Read</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.Read.html" title="struct futures::io::Read">Read</a><'_, R></span><code class="content"><span class="where fmt-newline">impl<R> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.Read.html" title="struct futures::io::Read">Read</a><'_, R><span class="where fmt-newline">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><br> <span class="where">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a></span>, |
| { ... } |
| <span class="item-spacer"></span> fn <a href="#method.read_vectored" class="fnname">read_vectored</a>(<br> &'a mut self,<br> bufs: &'a mut [<a class="struct" href="struct.IoSliceMut.html" title="struct futures::io::IoSliceMut">IoSliceMut</a><'a>]<br> ) -> <a class="struct" href="struct.ReadVectored.html" title="struct futures::io::ReadVectored">ReadVectored</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.ReadVectored.html" title="struct futures::io::ReadVectored">ReadVectored</a><'_, R></span><code class="content"><span class="where fmt-newline">impl<R> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.ReadVectored.html" title="struct futures::io::ReadVectored">ReadVectored</a><'_, R><span class="where fmt-newline">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><br> <span class="where">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a></span>, |
| { ... } |
| <span class="item-spacer"></span> fn <a href="#method.read_exact" class="fnname">read_exact</a>(&'a mut self, buf: &'a mut [<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]) -> <a class="struct" href="struct.ReadExact.html" title="struct futures::io::ReadExact">ReadExact</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.ReadExact.html" title="struct futures::io::ReadExact">ReadExact</a><'_, R></span><code class="content"><span class="where fmt-newline">impl<R> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.ReadExact.html" title="struct futures::io::ReadExact">ReadExact</a><'_, R><span class="where fmt-newline">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><br> <span class="where">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a></span>, |
| { ... } |
| <span class="item-spacer"></span> fn <a href="#method.read_to_end" class="fnname">read_to_end</a>(<br> &'a mut self,<br> buf: &'a mut <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/alloc/struct.Global.html" title="struct alloc::alloc::Global">Global</a>><br> ) -> <a class="struct" href="struct.ReadToEnd.html" title="struct futures::io::ReadToEnd">ReadToEnd</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.ReadToEnd.html" title="struct futures::io::ReadToEnd">ReadToEnd</a><'_, A></span><code class="content"><span class="where fmt-newline">impl<A> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.ReadToEnd.html" title="struct futures::io::ReadToEnd">ReadToEnd</a><'_, A><span class="where fmt-newline">where<br> A: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><br> <span class="where">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a></span>, |
| { ... } |
| <span class="item-spacer"></span> fn <a href="#method.read_to_string" class="fnname">read_to_string</a>(<br> &'a mut self,<br> buf: &'a mut <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/string/struct.String.html" title="struct alloc::string::String">String</a><br> ) -> <a class="struct" href="struct.ReadToString.html" title="struct futures::io::ReadToString">ReadToString</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.ReadToString.html" title="struct futures::io::ReadToString">ReadToString</a><'_, A></span><code class="content"><span class="where fmt-newline">impl<A> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.ReadToString.html" title="struct futures::io::ReadToString">ReadToString</a><'_, A><span class="where fmt-newline">where<br> A: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><br> <span class="where">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a></span>, |
| { ... } |
| <span class="item-spacer"></span> fn <a href="#method.split" class="fnname">split</a>(self) -> (<a class="struct" href="struct.ReadHalf.html" title="struct futures::io::ReadHalf">ReadHalf</a><Self>, <a class="struct" href="struct.WriteHalf.html" title="struct futures::io::WriteHalf">WriteHalf</a><Self>)<br> <span class="where">where<br> Self: <a class="trait" href="trait.AsyncWrite.html" title="trait futures::io::AsyncWrite">AsyncWrite</a></span>, |
| { ... } |
| <span class="item-spacer"></span> fn <a href="#method.take" class="fnname">take</a>(self, limit: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a>) -> <a class="struct" href="struct.Take.html" title="struct futures::io::Take">Take</a><Self> { ... } |
| }</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>An extension trait which adds utility methods to <code>AsyncRead</code> types.</p> |
| </div></details><h2 id="provided-methods" class="small-section-header">Provided Methods<a href="#provided-methods" class="anchor"></a></h2><div class="methods"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.chain" class="method has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#172-175">source</a><h4 class="code-header">fn <a href="#method.chain" class="fnname">chain</a><R>(self, next: R) -> <a class="struct" href="struct.Chain.html" title="struct futures::io::Chain">Chain</a><Self, R><span class="where fmt-newline">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a>,</span></h4></section></summary><div class="docblock"><p>Creates an adaptor which will chain this stream with another.</p> |
| <p>The returned <code>AsyncRead</code> instance will first read all bytes from this object |
| until EOF is encountered. Afterwards the output is equivalent to the |
| output of <code>next</code>.</p> |
| <h5 id="examples"><a href="#examples">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>futures::io::{AsyncReadExt, Cursor}; |
| |
| <span class="kw">let </span>reader1 = Cursor::new([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]); |
| <span class="kw">let </span>reader2 = Cursor::new([<span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>]); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>reader = reader1.chain(reader2); |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = Vec::new(); |
| |
| <span class="comment">// read the value into a Vec. |
| </span>reader.read_to_end(<span class="kw-2">&mut </span>buffer).<span class="kw">await</span><span class="question-mark">?</span>; |
| <span class="macro">assert_eq!</span>(buffer, [<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>]);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.read" class="method has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#204-206">source</a><h4 class="code-header">fn <a href="#method.read" class="fnname">read</a>(&'a mut self, buf: &'a mut [<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]) -> <a class="struct" href="struct.Read.html" title="struct futures::io::Read">Read</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.Read.html" title="struct futures::io::Read">Read</a><'_, R></span><code class="content"><span class="where fmt-newline">impl<R> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.Read.html" title="struct futures::io::Read">Read</a><'_, R><span class="where fmt-newline">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><span class="where fmt-newline">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>,</span></h4></section></summary><div class="docblock"><p>Tries to read some bytes directly into the given <code>buf</code> in asynchronous |
| manner, returning a future type.</p> |
| <p>The returned future will resolve to the number of bytes read once the read |
| operation is completed.</p> |
| <h5 id="examples-1"><a href="#examples-1">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>futures::io::{AsyncReadExt, Cursor}; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>reader = Cursor::new([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]); |
| <span class="kw">let </span><span class="kw-2">mut </span>output = [<span class="number">0u8</span>; <span class="number">5</span>]; |
| |
| <span class="kw">let </span>bytes = reader.read(<span class="kw-2">&mut </span>output[..]).<span class="kw">await</span><span class="question-mark">?</span>; |
| |
| <span class="comment">// This is only guaranteed to be 4 because `&[u8]` is a synchronous |
| // reader. In a real system you could get anywhere from 1 to |
| // `output.len()` bytes in a single read. |
| </span><span class="macro">assert_eq!</span>(bytes, <span class="number">4</span>); |
| <span class="macro">assert_eq!</span>(output, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">0</span>]);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.read_vectored" class="method has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#216-218">source</a><h4 class="code-header">fn <a href="#method.read_vectored" class="fnname">read_vectored</a>(<br> &'a mut self,<br> bufs: &'a mut [<a class="struct" href="struct.IoSliceMut.html" title="struct futures::io::IoSliceMut">IoSliceMut</a><'a>]<br>) -> <a class="struct" href="struct.ReadVectored.html" title="struct futures::io::ReadVectored">ReadVectored</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.ReadVectored.html" title="struct futures::io::ReadVectored">ReadVectored</a><'_, R></span><code class="content"><span class="where fmt-newline">impl<R> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.ReadVectored.html" title="struct futures::io::ReadVectored">ReadVectored</a><'_, R><span class="where fmt-newline">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><span class="where fmt-newline">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>,</span></h4></section></summary><div class="docblock"><p>Creates a future which will read from the <code>AsyncRead</code> into <code>bufs</code> using vectored |
| IO operations.</p> |
| <p>The returned future will resolve to the number of bytes read once the read |
| operation is completed.</p> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.read_exact" class="method has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#260-262">source</a><h4 class="code-header">fn <a href="#method.read_exact" class="fnname">read_exact</a>(&'a mut self, buf: &'a mut [<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>]) -> <a class="struct" href="struct.ReadExact.html" title="struct futures::io::ReadExact">ReadExact</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.ReadExact.html" title="struct futures::io::ReadExact">ReadExact</a><'_, R></span><code class="content"><span class="where fmt-newline">impl<R> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.ReadExact.html" title="struct futures::io::ReadExact">ReadExact</a><'_, R><span class="where fmt-newline">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><span class="where fmt-newline">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>,</span></h4></section></summary><div class="docblock"><p>Creates a future which will read exactly enough bytes to fill <code>buf</code>, |
| returning an error if end of file (EOF) is hit sooner.</p> |
| <p>The returned future will resolve once the read operation is completed.</p> |
| <p>In the case of an error the buffer and the object will be discarded, with |
| the error yielded.</p> |
| <h5 id="examples-2"><a href="#examples-2">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>futures::io::{AsyncReadExt, Cursor}; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>reader = Cursor::new([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]); |
| <span class="kw">let </span><span class="kw-2">mut </span>output = [<span class="number">0u8</span>; <span class="number">4</span>]; |
| |
| reader.read_exact(<span class="kw-2">&mut </span>output).<span class="kw">await</span><span class="question-mark">?</span>; |
| |
| <span class="macro">assert_eq!</span>(output, [<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]);</code></pre></div> |
| <h6 id="eof-is-hit-before-buf-is-filled"><a href="#eof-is-hit-before-buf-is-filled">EOF is hit before <code>buf</code> is filled</a></h6> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>futures::io::{<span class="self">self</span>, AsyncReadExt, Cursor}; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>reader = Cursor::new([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]); |
| <span class="kw">let </span><span class="kw-2">mut </span>output = [<span class="number">0u8</span>; <span class="number">5</span>]; |
| |
| <span class="kw">let </span>result = reader.read_exact(<span class="kw-2">&mut </span>output).<span class="kw">await</span>; |
| |
| <span class="macro">assert_eq!</span>(result.unwrap_err().kind(), io::ErrorKind::UnexpectedEof);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.read_to_end" class="method has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#286-288">source</a><h4 class="code-header">fn <a href="#method.read_to_end" class="fnname">read_to_end</a>(&'a mut self, buf: &'a mut <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/vec/struct.Vec.html" title="struct alloc::vec::Vec">Vec</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u8.html">u8</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/alloc/struct.Global.html" title="struct alloc::alloc::Global">Global</a>>) -> <a class="struct" href="struct.ReadToEnd.html" title="struct futures::io::ReadToEnd">ReadToEnd</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.ReadToEnd.html" title="struct futures::io::ReadToEnd">ReadToEnd</a><'_, A></span><code class="content"><span class="where fmt-newline">impl<A> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.ReadToEnd.html" title="struct futures::io::ReadToEnd">ReadToEnd</a><'_, A><span class="where fmt-newline">where<br> A: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><span class="where fmt-newline">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>,</span></h4></section></summary><div class="docblock"><p>Creates a future which will read all the bytes from this <code>AsyncRead</code>.</p> |
| <p>On success the total number of bytes read is returned.</p> |
| <h5 id="examples-3"><a href="#examples-3">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>futures::io::{AsyncReadExt, Cursor}; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>reader = Cursor::new([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]); |
| <span class="kw">let </span><span class="kw-2">mut </span>output = Vec::with_capacity(<span class="number">4</span>); |
| |
| <span class="kw">let </span>bytes = reader.read_to_end(<span class="kw-2">&mut </span>output).<span class="kw">await</span><span class="question-mark">?</span>; |
| |
| <span class="macro">assert_eq!</span>(bytes, <span class="number">4</span>); |
| <span class="macro">assert_eq!</span>(output, <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>]);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.read_to_string" class="method has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#312-314">source</a><h4 class="code-header">fn <a href="#method.read_to_string" class="fnname">read_to_string</a>(&'a mut self, buf: &'a mut <a class="struct" href="https://doc.rust-lang.org/nightly/alloc/string/struct.String.html" title="struct alloc::string::String">String</a>) -> <a class="struct" href="struct.ReadToString.html" title="struct futures::io::ReadToString">ReadToString</a><'a, Self><span class="notable-traits"><span class="notable-traits-tooltip">ⓘ<span class="notable-traits-tooltiptext"><span class="docblock"><span class="notable">Notable traits for <a class="struct" href="struct.ReadToString.html" title="struct futures::io::ReadToString">ReadToString</a><'_, A></span><code class="content"><span class="where fmt-newline">impl<A> <a class="trait" href="../future/trait.Future.html" title="trait futures::future::Future">Future</a> for <a class="struct" href="struct.ReadToString.html" title="struct futures::io::ReadToString">ReadToString</a><'_, A><span class="where fmt-newline">where<br> A: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></span><span class="where fmt-newline"> type <a href="../future/trait.Future.html#associatedtype.Output" class="associatedtype">Output</a> = <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a><<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>, <a class="struct" href="struct.Error.html" title="struct futures::io::Error">Error</a>>;</span></code></span></span></span></span><span class="where fmt-newline">where<br> Self: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Unpin.html" title="trait core::marker::Unpin">Unpin</a>,</span></h4></section></summary><div class="docblock"><p>Creates a future which will read all the bytes from this <code>AsyncRead</code>.</p> |
| <p>On success the total number of bytes read is returned.</p> |
| <h5 id="examples-4"><a href="#examples-4">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>futures::io::{AsyncReadExt, Cursor}; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>reader = Cursor::new(<span class="kw-2">&</span><span class="string">b"1234"</span>[..]); |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = String::with_capacity(<span class="number">4</span>); |
| |
| <span class="kw">let </span>bytes = reader.read_to_string(<span class="kw-2">&mut </span>buffer).<span class="kw">await</span><span class="question-mark">?</span>; |
| |
| <span class="macro">assert_eq!</span>(bytes, <span class="number">4</span>); |
| <span class="macro">assert_eq!</span>(buffer, String::from(<span class="string">"1234"</span>));</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.split" class="method has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#348-350">source</a><h4 class="code-header">fn <a href="#method.split" class="fnname">split</a>(self) -> (<a class="struct" href="struct.ReadHalf.html" title="struct futures::io::ReadHalf">ReadHalf</a><Self>, <a class="struct" href="struct.WriteHalf.html" title="struct futures::io::WriteHalf">WriteHalf</a><Self>)<span class="where fmt-newline">where<br> Self: <a class="trait" href="trait.AsyncWrite.html" title="trait futures::io::AsyncWrite">AsyncWrite</a>,</span></h4></section></summary><div class="docblock"><p>Helper method for splitting this read/write object into two halves.</p> |
| <p>The two halves returned implement the <code>AsyncRead</code> and <code>AsyncWrite</code> |
| traits, respectively.</p> |
| <h5 id="examples-5"><a href="#examples-5">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>futures::io::{<span class="self">self</span>, AsyncReadExt, Cursor}; |
| |
| <span class="comment">// Note that for `Cursor` the read and write halves share a single |
| // seek position. This may or may not be true for other types that |
| // implement both `AsyncRead` and `AsyncWrite`. |
| |
| </span><span class="kw">let </span>reader = Cursor::new([<span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>]); |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = Cursor::new(<span class="macro">vec!</span>[<span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">0</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>]); |
| <span class="kw">let </span><span class="kw-2">mut </span>writer = Cursor::new(<span class="macro">vec!</span>[<span class="number">0u8</span>; <span class="number">5</span>]); |
| |
| { |
| <span class="kw">let </span>(buffer_reader, <span class="kw-2">mut </span>buffer_writer) = (<span class="kw-2">&mut </span>buffer).split(); |
| io::copy(reader, <span class="kw-2">&mut </span>buffer_writer).<span class="kw">await</span><span class="question-mark">?</span>; |
| io::copy(buffer_reader, <span class="kw-2">&mut </span>writer).<span class="kw">await</span><span class="question-mark">?</span>; |
| } |
| |
| <span class="macro">assert_eq!</span>(buffer.into_inner(), [<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="macro">assert_eq!</span>(writer.into_inner(), [<span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">8</span>, <span class="number">0</span>]);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.take" class="method has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#375-377">source</a><h4 class="code-header">fn <a href="#method.take" class="fnname">take</a>(self, limit: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.u64.html">u64</a>) -> <a class="struct" href="struct.Take.html" title="struct futures::io::Take">Take</a><Self></h4></section></summary><div class="docblock"><p>Creates an AsyncRead adapter which will read at most <code>limit</code> bytes |
| from the underlying reader.</p> |
| <h5 id="examples-6"><a href="#examples-6">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>futures::io::{AsyncReadExt, Cursor}; |
| |
| <span class="kw">let </span>reader = Cursor::new(<span class="kw-2">&</span><span class="string">b"12345678"</span>[..]); |
| <span class="kw">let </span><span class="kw-2">mut </span>buffer = [<span class="number">0</span>; <span class="number">5</span>]; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>take = reader.take(<span class="number">4</span>); |
| <span class="kw">let </span>n = take.read(<span class="kw-2">&mut </span>buffer).<span class="kw">await</span><span class="question-mark">?</span>; |
| |
| <span class="macro">assert_eq!</span>(n, <span class="number">4</span>); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span>buffer, <span class="string">b"1234\0"</span>);</code></pre></div> |
| </div></details></div><h2 id="implementors" class="small-section-header">Implementors<a href="#implementors" class="anchor"></a></h2><div id="implementors-list"><section id="impl-AsyncReadExt-for-R" class="impl has-srclink"><a class="srclink rightside" href="../../src/futures_util/io/mod.rs.html#398">source</a><a href="#impl-AsyncReadExt-for-R" class="anchor"></a><h3 class="code-header">impl<R> <a class="trait" href="trait.AsyncReadExt.html" title="trait futures::io::AsyncReadExt">AsyncReadExt</a> for R<span class="where fmt-newline">where<br> R: <a class="trait" href="trait.AsyncRead.html" title="trait futures::io::AsyncRead">AsyncRead</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,</span></h3></section></div><script src="../../implementors/futures_util/io/trait.AsyncReadExt.js" async></script></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="futures" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
