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<!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="Get a length-prefixed slice (TLV)"><title>length_take in winnow::binary - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><link rel="stylesheet" href="../../static.files/normalize-76eba96aa4d2e634.css"><link rel="stylesheet" href="../../static.files/rustdoc-5bc39a1768837dd0.css"><meta name="rustdoc-vars" data-root-path="../../" data-static-root-path="../../static.files/" data-current-crate="winnow" data-themes="" data-resource-suffix="" data-rustdoc-version="1.77.0 (aedd173a2 2024-03-17)" data-channel="1.77.0" data-search-js="search-dd67cee4cfa65049.js" data-settings-js="settings-4313503d2e1961c2.js" ><script src="../../static.files/storage-4c98445ec4002617.js"></script><script defer src="sidebar-items.js"></script><script defer src="../../static.files/main-48f368f3872407c8.js"></script><noscript><link rel="stylesheet" href="../../static.files/noscript-04d5337699b92874.css"></noscript><link rel="alternate icon" type="image/png" href="../../static.files/favicon-16x16-8b506e7a72182f1c.png"><link rel="alternate icon" type="image/png" href="../../static.files/favicon-32x32-422f7d1d52889060.png"><link rel="icon" type="image/svg+xml" href="../../static.files/favicon-2c020d218678b618.svg"></head><body class="rustdoc fn"><!--[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" title="show sidebar"></button></nav><nav class="sidebar"><div class="sidebar-crate"><h2><a href="../../winnow/index.html">winnow</a><span class="version">0.6.5</span></h2></div><div class="sidebar-elems"><h2><a href="index.html">In winnow::binary</a></h2></div></nav><div class="sidebar-resizer"></div>
<main><div class="width-limiter"><nav class="sub"><form class="search-form"><span></span><div id="sidebar-button" tabindex="-1"><a href="../../winnow/all.html" title="show sidebar"></a></div><input class="search-input" name="search" aria-label="Run search in the documentation" autocomplete="off" spellcheck="false" placeholder="Click or press S to search, ? for more options…" type="search"><div id="help-button" tabindex="-1"><a href="../../help.html" title="help">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1>Function <a href="../index.html">winnow</a>::<wbr><a href="index.html">binary</a>::<wbr><a class="fn" href="#">length_take</a><button id="copy-path" title="Copy item path to clipboard"><img src="../../static.files/clipboard-7571035ce49a181d.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="src" href="../../src/winnow/binary/mod.rs.html#2422-2436">source</a> · <button id="toggle-all-docs" title="collapse all docs">[<span>&#x2212;</span>]</button></span></div><pre class="rust item-decl"><code>pub fn length_take&lt;Input, Count, Error, CountParser&gt;(
count: CountParser
) -&gt; impl <a class="trait" href="../trait.Parser.html" title="trait winnow::Parser">Parser</a>&lt;Input, &lt;Input as <a class="trait" href="../stream/trait.Stream.html" title="trait winnow::stream::Stream">Stream</a>&gt;::<a class="associatedtype" href="../stream/trait.Stream.html#associatedtype.Slice" title="type winnow::stream::Stream::Slice">Slice</a>, Error&gt;<div class="where">where
Input: <a class="trait" href="../stream/trait.StreamIsPartial.html" title="trait winnow::stream::StreamIsPartial">StreamIsPartial</a> + <a class="trait" href="../stream/trait.Stream.html" title="trait winnow::stream::Stream">Stream</a>,
Count: <a class="trait" href="../stream/trait.ToUsize.html" title="trait winnow::stream::ToUsize">ToUsize</a>,
CountParser: <a class="trait" href="../trait.Parser.html" title="trait winnow::Parser">Parser</a>&lt;Input, Count, Error&gt;,
Error: <a class="trait" href="../error/trait.ParserError.html" title="trait winnow::error::ParserError">ParserError</a>&lt;Input&gt;,</div></code></pre><details class="toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>Get a length-prefixed slice (<a href="https://en.wikipedia.org/wiki/Type-length-value">TLV</a>)</p>
<p>To apply a parser to the returned slice, see <a href="fn.length_and_then.html" title="fn winnow::binary::length_and_then"><code>length_and_then</code></a>.</p>
<p>If the count is for something besides tokens, see <a href="fn.length_repeat.html" title="fn winnow::binary::length_repeat"><code>length_repeat</code></a>.</p>
<p><em>Complete version</em>: Returns an error if there is not enough input data.</p>
<p><em>[Partial version][crate::_topic::partial]</em>: Will return <code>Err(winnow::error::ErrMode::Incomplete(_))</code> if there is not enough data.</p>
<h2 id="example"><a class="doc-anchor" href="#example">§</a>Example</h2>
<div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>winnow::Bytes;
<span class="kw">use </span>winnow::binary::be_u16;
<span class="kw">use </span>winnow::binary::length_take;
<span class="kw">type </span>Stream&lt;<span class="lifetime">'i</span>&gt; = Partial&lt;<span class="kw-2">&amp;</span><span class="lifetime">'i </span>Bytes&gt;;
<span class="kw">fn </span>stream(b: <span class="kw-2">&amp;</span>[u8]) -&gt; Stream&lt;<span class="lifetime">'_</span>&gt; {
Partial::new(Bytes::new(b))
}
<span class="kw">fn </span>parser(s: Stream&lt;<span class="lifetime">'_</span>&gt;) -&gt; IResult&lt;Stream&lt;<span class="lifetime">'_</span>&gt;, <span class="kw-2">&amp;</span>[u8]&gt; {
length_take(be_u16).parse_peek(s)
}
<span class="macro">assert_eq!</span>(parser(stream(<span class="string">b"\x00\x03abcefg"</span>)), <span class="prelude-val">Ok</span>((stream(<span class="kw-2">&amp;</span><span class="string">b"efg"</span>[..]), <span class="kw-2">&amp;</span><span class="string">b"abc"</span>[..])));
<span class="macro">assert_eq!</span>(parser(stream(<span class="string">b"\x00\x03a"</span>)), <span class="prelude-val">Err</span>(ErrMode::Incomplete(Needed::new(<span class="number">2</span>))));</code></pre></div>
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