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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="API documentation for the Rust `HeaderMap` struct in crate `actix_web`."><meta name="keywords" content="rust, rustlang, rust-lang, HeaderMap"><title>actix_web::http::header::HeaderMap - Rust</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="../../../dark.css"><link rel="stylesheet" type="text/css" href="../../../light.css" id="themeStyle"><script src="../../../storage.js"></script></head><body class="rustdoc struct"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">&#9776;</div><p class='location'>Struct HeaderMap</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#methods">Methods</a><div class="sidebar-links"><a href="#method.new">new</a><a href="#method.with_capacity">with_capacity</a><a href="#method.len">len</a><a href="#method.keys_len">keys_len</a><a href="#method.is_empty">is_empty</a><a href="#method.clear">clear</a><a href="#method.capacity">capacity</a><a href="#method.reserve">reserve</a><a href="#method.get">get</a><a href="#method.get_mut">get_mut</a><a href="#method.get_all">get_all</a><a href="#method.contains_key">contains_key</a><a href="#method.iter">iter</a><a href="#method.iter_mut">iter_mut</a><a href="#method.keys">keys</a><a href="#method.values">values</a><a href="#method.values_mut">values_mut</a><a href="#method.drain">drain</a><a href="#method.entry">entry</a><a href="#method.insert">insert</a><a href="#method.append">append</a><a href="#method.remove">remove</a></div><a class="sidebar-title" href="#implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-IntoIterator">IntoIterator</a><a href="#impl-FromIterator%3C(HeaderName%2C%20T)%3E">FromIterator&lt;(HeaderName, T)&gt;</a><a href="#impl-Debug">Debug</a><a href="#impl-Eq">Eq</a><a href="#impl-Default">Default</a><a href="#impl-PartialEq%3CHeaderMap%3CT%3E%3E">PartialEq&lt;HeaderMap&lt;T&gt;&gt;</a><a href="#impl-Extend%3C(HeaderName%2C%20T)%3E">Extend&lt;(HeaderName, T)&gt;</a><a href="#impl-Extend%3C(Option%3CHeaderName%3E%2C%20T)%3E">Extend&lt;(Option&lt;HeaderName&gt;, T)&gt;</a><a href="#impl-Clone">Clone</a><a href="#impl-Index%3CK%3E">Index&lt;K&gt;</a></div><a class="sidebar-title" href="#synthetic-implementations">Auto Trait Implementations</a><div class="sidebar-links"><a href="#impl-Send">Send</a><a href="#impl-Sync">Sync</a></div></div><p class='location'><a href='../../index.html'>actix_web</a>::<wbr><a href='../index.html'>http</a>::<wbr><a href='index.html'>header</a></p><script>window.sidebarCurrent = {name: 'HeaderMap', ty: 'struct', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><a id="settings-menu" href="../../../settings.html"><img src="../../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='in-band'>Struct <a href='../../index.html'>actix_web</a>::<wbr><a href='../index.html'>http</a>::<wbr><a href='index.html'>header</a>::<wbr><a class="struct" href=''>HeaderMap</a></span><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>&#x2212;</span>]</a></span><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#39-46' title='goto source code'>[src]</a></span></h1><div class="docblock type-decl"><pre class='rust struct'>pub struct HeaderMap&lt;T&nbsp;=&nbsp;<a class="struct" href="../../../actix_web/http/header/struct.HeaderValue.html" title="struct actix_web::http::header::HeaderValue">HeaderValue</a>&gt; { /* fields omitted */ }</pre></div><div class='docblock'><p>A set of HTTP headers</p>
<p><code>HeaderMap</code> is an multimap of <code>HeaderName</code> to values.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<p>Basic usage</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">headers</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">headers</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;example.com&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">headers</span>.<span class="ident">insert</span>(<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">headers</span>.<span class="ident">contains_key</span>(<span class="ident">HOST</span>));
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">headers</span>.<span class="ident">contains_key</span>(<span class="ident">LOCATION</span>));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">headers</span>[<span class="ident">HOST</span>], <span class="string">&quot;example.com&quot;</span>);
<span class="ident">headers</span>.<span class="ident">remove</span>(<span class="ident">HOST</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">headers</span>.<span class="ident">contains_key</span>(<span class="ident">HOST</span>));</pre>
</div>
<h2 id='methods' class='small-section-header'>
Methods<a href='#methods' class='anchor'></a>
</h2>
<h3 id='impl' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;<a class="struct" href="../../../actix_web/http/header/struct.HeaderValue.html" title="struct actix_web::http::header::HeaderValue">HeaderValue</a>&gt;</code><a href='#impl' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#415-433' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.new' class="method"><span id='new.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.new' class='fnname'>new</a>() -&gt; <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;<a class="struct" href="../../../actix_web/http/header/struct.HeaderValue.html" title="struct actix_web::http::header::HeaderValue">HeaderValue</a>&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#430-432' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Create an empty <code>HeaderMap</code>.</p>
<p>The map will be created without any capacity. This function will not
allocate.</p>
<h1 id="examples-1" class="section-header"><a href="#examples-1">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">is_empty</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">0</span>, <span class="ident">map</span>.<span class="ident">capacity</span>());</pre>
</div></div><h3 id='impl-1' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code><a href='#impl-1' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#435-1636' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.with_capacity' class="method"><span id='with_capacity.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.with_capacity' class='fnname'>with_capacity</a>(capacity: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#454-484' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Create an empty <code>HeaderMap</code> with the specified capacity.</p>
<p>The returned map will allocate internal storage in order to hold about
<code>capacity</code> elements without reallocating. However, this is a &quot;best
effort&quot; as there are usage patterns that could cause additional
allocations before <code>capacity</code> headers are stored in the map.</p>
<p>More capacity than requested may be allocated.</p>
<h1 id="examples-2" class="section-header"><a href="#examples-2">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">map</span>: <span class="ident">HeaderMap</span><span class="op">&lt;</span><span class="ident">u32</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">with_capacity</span>(<span class="number">10</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">is_empty</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">12</span>, <span class="ident">map</span>.<span class="ident">capacity</span>());</pre>
</div><h4 id='method.len' class="method"><span id='len.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.len' class='fnname'>len</a>(&amp;self) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#510-512' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns the number of headers stored in the map.</p>
<p>This number represents the total number of <strong>values</strong> stored in the map.
This number can be greater than or equal to the number of <strong>keys</strong>
stored given that a single key may have more than one associated value.</p>
<h1 id="examples-3" class="section-header"><a href="#examples-3">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">0</span>, <span class="ident">map</span>.<span class="ident">len</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">ACCEPT</span>, <span class="string">&quot;text/plain&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;localhost&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">2</span>, <span class="ident">map</span>.<span class="ident">len</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">ACCEPT</span>, <span class="string">&quot;text/html&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">3</span>, <span class="ident">map</span>.<span class="ident">len</span>());</pre>
</div><h4 id='method.keys_len' class="method"><span id='keys_len.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.keys_len' class='fnname'>keys_len</a>(&amp;self) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#537-539' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns the number of keys stored in the map.</p>
<p>This number will be less than or equal to <code>len()</code> as each key may have
more than one associated value.</p>
<h1 id="examples-4" class="section-header"><a href="#examples-4">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">0</span>, <span class="ident">map</span>.<span class="ident">keys_len</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">ACCEPT</span>, <span class="string">&quot;text/plain&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;localhost&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">2</span>, <span class="ident">map</span>.<span class="ident">keys_len</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">ACCEPT</span>, <span class="string">&quot;text/html&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">2</span>, <span class="ident">map</span>.<span class="ident">keys_len</span>());</pre>
</div><h4 id='method.is_empty' class="method"><span id='is_empty.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.is_empty' class='fnname'>is_empty</a>(&amp;self) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#556-558' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns true if the map contains no elements.</p>
<h1 id="examples-5" class="section-header"><a href="#examples-5">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">is_empty</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello.world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">map</span>.<span class="ident">is_empty</span>());</pre>
</div><h4 id='method.clear' class="method"><span id='clear.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.clear' class='fnname'>clear</a>(&amp;mut self)</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#575-583' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Clears the map, removing all key-value pairs. Keeps the allocated memory
for reuse.</p>
<h1 id="examples-6" class="section-header"><a href="#examples-6">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello.world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">clear</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">is_empty</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">capacity</span>() <span class="op">&gt;</span> <span class="number">0</span>);</pre>
</div><h4 id='method.capacity' class="method"><span id='capacity.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.capacity' class='fnname'>capacity</a>(&amp;self) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#602-604' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns the number of headers the map can hold without reallocating.</p>
<p>This number is an approximation as certain usage patterns could cause
additional allocations before the returned capacity is filled.</p>
<h1 id="examples-7" class="section-header"><a href="#examples-7">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">0</span>, <span class="ident">map</span>.<span class="ident">capacity</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello.world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">6</span>, <span class="ident">map</span>.<span class="ident">capacity</span>());</pre>
</div><h4 id='method.reserve' class="method"><span id='reserve.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.reserve' class='fnname'>reserve</a>(&amp;mut self, additional: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.usize.html">usize</a>)</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#628-646' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Reserves capacity for at least <code>additional</code> more headers to be inserted
into the <code>HeaderMap</code>.</p>
<p>The header map may reserve more space to avoid frequent reallocations.
Like with <code>with_capacity</code>, this will be a &quot;best effort&quot; to avoid
allocations until <code>additional</code> more headers are inserted. Certain usage
patterns could cause additional allocations before the number is
reached.</p>
<h1 id="panics" class="section-header"><a href="#panics">Panics</a></h1>
<p>Panics if the new allocation size overflows <code>usize</code>.</p>
<h1 id="examples-8" class="section-header"><a href="#examples-8">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">reserve</span>(<span class="number">10</span>);</pre>
</div><h4 id='method.get' class="method"><span id='get.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.get' class='fnname'>get</a>&lt;K&gt;(&amp;self, key: K) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;</a>T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.AsHeaderName.html" title="trait actix_web::http::header::AsHeaderName">AsHeaderName</a>,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#669-679' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns a reference to the value associated with the key.</p>
<p>If there are multiple values associated with the key, then the first one
is returned. Use <code>get_all</code> to get all values associated with a given
key. Returns <code>None</code> if there are no values associated with the key.</p>
<h1 id="examples-9" class="section-header"><a href="#examples-9">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">get</span>(<span class="string">&quot;host&quot;</span>).<span class="ident">is_none</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">get</span>(<span class="ident">HOST</span>).<span class="ident">unwrap</span>(), <span class="kw-2">&amp;</span><span class="string">&quot;hello&quot;</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">get</span>(<span class="string">&quot;host&quot;</span>).<span class="ident">unwrap</span>(), <span class="kw-2">&amp;</span><span class="string">&quot;hello&quot;</span>);
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">get</span>(<span class="string">&quot;host&quot;</span>).<span class="ident">unwrap</span>(), <span class="kw-2">&amp;</span><span class="string">&quot;hello&quot;</span>);</pre>
</div><h4 id='method.get_mut' class="method"><span id='get_mut.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.get_mut' class='fnname'>get_mut</a>&lt;K&gt;(&amp;mut self, key: K) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;mut </a>T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.AsHeaderName.html" title="trait actix_web::http::header::AsHeaderName">AsHeaderName</a>,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#698-708' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns a mutable reference to the value associated with the key.</p>
<p>If there are multiple values associated with the key, then the first one
is returned. Use <code>entry</code> to get all values associated with a given
key. Returns <code>None</code> if there are no values associated with the key.</p>
<h1 id="examples-10" class="section-header"><a href="#examples-10">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">default</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">to_string</span>());
<span class="ident">map</span>.<span class="ident">get_mut</span>(<span class="string">&quot;host&quot;</span>).<span class="ident">unwrap</span>().<span class="ident">push_str</span>(<span class="string">&quot;-world&quot;</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">get</span>(<span class="ident">HOST</span>).<span class="ident">unwrap</span>(), <span class="kw-2">&amp;</span><span class="string">&quot;hello-world&quot;</span>);</pre>
</div><h4 id='method.get_all' class="method"><span id='get_all.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.get_all' class='fnname'>get_all</a>&lt;K&gt;(&amp;self, key: K) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.GetAll.html" title="struct actix_web::http::header::GetAll">GetAll</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.AsHeaderName.html" title="trait actix_web::http::header::AsHeaderName">AsHeaderName</a>,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#735-742' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns a view of all values associated with a key.</p>
<p>The returned view does not incur any allocations and allows iterating
the values associated with the key. See <a href="struct.GetAll.html"><code>GetAll</code></a> for more details.
Returns <code>None</code> if there are no values associated with the key.</p>
<h1 id="examples-11" class="section-header"><a href="#examples-11">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;goodbye&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">let</span> <span class="ident">view</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_all</span>(<span class="string">&quot;host&quot;</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">view</span>.<span class="ident">iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&amp;</span><span class="string">&quot;hello&quot;</span>, <span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="kw-2">&amp;</span><span class="string">&quot;goodbye&quot;</span>, <span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">is_none</span>());</pre>
</div><h4 id='method.contains_key' class="method"><span id='contains_key.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.contains_key' class='fnname'>contains_key</a>&lt;K&gt;(&amp;self, key: K) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a> <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.AsHeaderName.html" title="trait actix_web::http::header::AsHeaderName">AsHeaderName</a>,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#757-761' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns true if the map contains a value for the specified key.</p>
<h1 id="examples-12" class="section-header"><a href="#examples-12">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">map</span>.<span class="ident">contains_key</span>(<span class="ident">HOST</span>));
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">contains_key</span>(<span class="string">&quot;host&quot;</span>));</pre>
</div><h4 id='method.iter' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;'a, T&gt;</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;'a, T&gt;</h3><code class="content"><span class="where fmt-newline">impl&lt;'a, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> for <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;'a, T&gt;</span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a>&amp;'a <a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a </a>T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>;</span></code></div></div><span id='iter.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.iter' class='fnname'>iter</a>(&amp;self) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#784-793' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>An iterator visiting all key-value pairs.</p>
<p>The iteration order is arbitrary, but consistent across platforms for
the same crate version. Each key will be yielded once per associated
value. So, if a key has 3 associated values, it will be yielded 3 times.</p>
<h1 id="examples-13" class="section-header"><a href="#examples-13">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;goodbye&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">for</span> (<span class="ident">key</span>, <span class="ident">value</span>) <span class="kw">in</span> <span class="ident">map</span>.<span class="ident">iter</span>() {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;{:?}: {:?}&quot;</span>, <span class="ident">key</span>, <span class="ident">value</span>);
}</pre>
</div><h4 id='method.iter_mut' class="method"><span id='iter_mut.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.iter_mut' class='fnname'>iter_mut</a>(&amp;mut self) -&gt; IterMut&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#816-823' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>An iterator visiting all key-value pairs, with mutable value references.</p>
<p>The iterator order is arbitrary, but consistent across platforms for the
same crate version. Each key will be yielded once per associated value,
so if a key has 3 associated values, it will be yielded 3 times.</p>
<h1 id="examples-14" class="section-header"><a href="#examples-14">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">default</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">to_string</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;goodbye&quot;</span>.<span class="ident">to_string</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">to_string</span>());
<span class="kw">for</span> (<span class="ident">key</span>, <span class="ident">value</span>) <span class="kw">in</span> <span class="ident">map</span>.<span class="ident">iter_mut</span>() {
<span class="ident">value</span>.<span class="ident">push_str</span>(<span class="string">&quot;-boop&quot;</span>);
}</pre>
</div><h4 id='method.keys' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Keys.html" title="struct actix_web::http::header::Keys">Keys</a>&lt;'a, T&gt;</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Keys.html" title="struct actix_web::http::header::Keys">Keys</a>&lt;'a, T&gt;</h3><code class="content"><span class="where fmt-newline">impl&lt;'a, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> for <a class="struct" href="../../../actix_web/http/header/struct.Keys.html" title="struct actix_web::http::header::Keys">Keys</a>&lt;'a, T&gt;</span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = &amp;'a <a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>;</span></code></div></div><span id='keys.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.keys' class='fnname'>keys</a>(&amp;self) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.Keys.html" title="struct actix_web::http::header::Keys">Keys</a>&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#846-848' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>An iterator visiting all keys.</p>
<p>The iteration order is arbitrary, but consistent across platforms for
the same crate version. Each key will be yielded only once even if it
has multiple associated values.</p>
<h1 id="examples-15" class="section-header"><a href="#examples-15">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;goodbye&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">for</span> <span class="ident">key</span> <span class="kw">in</span> <span class="ident">map</span>.<span class="ident">keys</span>() {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;{:?}&quot;</span>, <span class="ident">key</span>);
}</pre>
</div><h4 id='method.values' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Values.html" title="struct actix_web::http::header::Values">Values</a>&lt;'a, T&gt;</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Values.html" title="struct actix_web::http::header::Values">Values</a>&lt;'a, T&gt;</h3><code class="content"><span class="where fmt-newline">impl&lt;'a, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> for <a class="struct" href="../../../actix_web/http/header/struct.Values.html" title="struct actix_web::http::header::Values">Values</a>&lt;'a, T&gt;</span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a </a>T;</span></code></div></div><span id='values.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.values' class='fnname'>values</a>(&amp;self) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.Values.html" title="struct actix_web::http::header::Values">Values</a>&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#870-872' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>An iterator visiting all values.</p>
<p>The iteration order is arbitrary, but consistent across platforms for
the same crate version.</p>
<h1 id="examples-16" class="section-header"><a href="#examples-16">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;goodbye&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">for</span> <span class="ident">value</span> <span class="kw">in</span> <span class="ident">map</span>.<span class="ident">values</span>() {
<span class="macro">println</span><span class="macro">!</span>(<span class="string">&quot;{:?}&quot;</span>, <span class="ident">value</span>);
}</pre>
</div><h4 id='method.values_mut' class="method"><span id='values_mut.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.values_mut' class='fnname'>values_mut</a>(&amp;mut self) -&gt; ValuesMut&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#894-896' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>An iterator visiting all values mutably.</p>
<p>The iteration order is arbitrary, but consistent across platforms for
the same crate version.</p>
<h1 id="examples-17" class="section-header"><a href="#examples-17">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">default</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">to_string</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;goodbye&quot;</span>.<span class="ident">to_string</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">to_string</span>());
<span class="kw">for</span> <span class="ident">value</span> <span class="kw">in</span> <span class="ident">map</span>.<span class="ident">values_mut</span>() {
<span class="ident">value</span>.<span class="ident">push_str</span>(<span class="string">&quot;-boop&quot;</span>);
}</pre>
</div><h4 id='method.drain' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Drain.html" title="struct actix_web::http::header::Drain">Drain</a>&lt;'a, T&gt;</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Drain.html" title="struct actix_web::http::header::Drain">Drain</a>&lt;'a, T&gt;</h3><code class="content"><span class="where fmt-newline">impl&lt;'a, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> for <a class="struct" href="../../../actix_web/http/header/struct.Drain.html" title="struct actix_web::http::header::Drain">Drain</a>&lt;'a, T&gt;</span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, <a class="struct" href="../../../actix_web/http/header/struct.ValueDrain.html" title="struct actix_web::http::header::ValueDrain">ValueDrain</a>&lt;'a, T&gt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>;</span></code></div></div><span id='drain.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.drain' class='fnname'>drain</a>(&amp;mut self) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.Drain.html" title="struct actix_web::http::header::Drain">Drain</a>&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#928-938' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Clears the map, returning all entries as an iterator.</p>
<p>The internal memory is kept for reuse.</p>
<h1 id="examples-18" class="section-header"><a href="#examples-18">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;goodbye&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">drain</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">drain</span>();
<span class="kw">let</span> (<span class="ident">key</span>, <span class="kw-2">mut</span> <span class="ident">vals</span>) <span class="op">=</span> <span class="ident">drain</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;host&quot;</span>, <span class="ident">key</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;hello&quot;</span>, <span class="ident">vals</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;goodbye&quot;</span>, <span class="ident">vals</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">vals</span>.<span class="ident">next</span>().<span class="ident">is_none</span>());
<span class="kw">let</span> (<span class="ident">key</span>, <span class="kw-2">mut</span> <span class="ident">vals</span>) <span class="op">=</span> <span class="ident">drain</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;content-length&quot;</span>, <span class="ident">key</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;123&quot;</span>, <span class="ident">vals</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">vals</span>.<span class="ident">next</span>().<span class="ident">is_none</span>());</pre>
</div><h4 id='method.entry' class="method"><span id='entry.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.entry' class='fnname'>entry</a>&lt;K&gt;(&amp;mut self, key: K) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;<a class="enum" href="../../../actix_web/http/header/enum.Entry.html" title="enum actix_web::http::header::Entry">Entry</a>&lt;T&gt;, <a class="struct" href="../../../actix_web/http/header/struct.InvalidHeaderName.html" title="struct actix_web::http::header::InvalidHeaderName">InvalidHeaderName</a>&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.AsHeaderName.html" title="trait actix_web::http::header::AsHeaderName">AsHeaderName</a>,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1012-1016' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Gets the given key's corresponding entry in the map for in-place
manipulation.</p>
<h1 id="examples-19" class="section-header"><a href="#examples-19">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span>: <span class="ident">HeaderMap</span><span class="op">&lt;</span><span class="ident">u32</span><span class="op">&gt;</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">default</span>();
<span class="kw">let</span> <span class="ident">headers</span> <span class="op">=</span> <span class="kw-2">&amp;</span>[
<span class="string">&quot;content-length&quot;</span>,
<span class="string">&quot;x-hello&quot;</span>,
<span class="string">&quot;Content-Length&quot;</span>,
<span class="string">&quot;x-world&quot;</span>,
];
<span class="kw">for</span> <span class="kw-2">&amp;</span><span class="ident">header</span> <span class="kw">in</span> <span class="ident">headers</span> {
<span class="kw">let</span> <span class="ident">counter</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">entry</span>(<span class="ident">header</span>).<span class="ident">unwrap</span>().<span class="ident">or_insert</span>(<span class="number">0</span>);
<span class="kw-2">*</span><span class="ident">counter</span> <span class="op">+=</span> <span class="number">1</span>;
}
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">&quot;content-length&quot;</span>], <span class="number">2</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">&quot;x-hello&quot;</span>], <span class="number">1</span>);</pre>
</div><h4 id='method.insert' class="method"><span id='insert.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.insert' class='fnname'>insert</a>&lt;K&gt;(&amp;mut self, key: K, val: T) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.IntoHeaderName.html" title="trait actix_web::http::header::IntoHeaderName">IntoHeaderName</a>,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1080-1084' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Inserts a key-value pair into the map.</p>
<p>If the map did not previously have this key present, then <code>None</code> is
returned.</p>
<p>If the map did have this key present, the new value is associated with
the key and all previous values are removed. <strong>Note</strong> that only a single
one of the previous values is returned. If there are multiple values
that have been previously associated with the key, then the first one is
returned. See <code>insert_mult</code> on <code>OccupiedEntry</code> for an API that returns
all values.</p>
<p>The key is not updated, though; this matters for types that can be <code>==</code>
without being identical.</p>
<h1 id="examples-20" class="section-header"><a href="#examples-20">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>()).<span class="ident">is_none</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">map</span>.<span class="ident">is_empty</span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">prev</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;earth&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>()).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;world&quot;</span>, <span class="ident">prev</span>);</pre>
</div><h4 id='method.append' class="method"><span id='append.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.append' class='fnname'>append</a>&lt;K&gt;(&amp;mut self, key: K, value: T) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a> <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.IntoHeaderName.html" title="trait actix_web::http::header::IntoHeaderName">IntoHeaderName</a>,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1173-1177' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Inserts a key-value pair into the map.</p>
<p>If the map did not previously have this key present, then <code>false</code> is
returned.</p>
<p>If the map did have this key present, the new value is pushed to the end
of the list of values currently associated with the key. The key is not
updated, though; this matters for types that can be <code>==</code> without being
identical.</p>
<h1 id="examples-21" class="section-header"><a href="#examples-21">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>()).<span class="ident">is_none</span>());
<span class="macro">assert</span><span class="macro">!</span>(<span class="op">!</span><span class="ident">map</span>.<span class="ident">is_empty</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">HOST</span>, <span class="string">&quot;earth&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">let</span> <span class="ident">values</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_all</span>(<span class="string">&quot;host&quot;</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">i</span> <span class="op">=</span> <span class="ident">values</span>.<span class="ident">iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;world&quot;</span>, <span class="kw-2">*</span><span class="ident">i</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>());
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;earth&quot;</span>, <span class="kw-2">*</span><span class="ident">i</span>.<span class="ident">next</span>().<span class="ident">unwrap</span>());</pre>
</div><h4 id='method.remove' class="method"><span id='remove.v' class='invisible'><table class='table-display'><tbody><tr><td><code>pub fn <a href='#method.remove' class='fnname'>remove</a>&lt;K&gt;(&amp;mut self, key: K) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.AsHeaderName.html" title="trait actix_web::http::header::AsHeaderName">AsHeaderName</a>,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1292-1307' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Removes a key from the map, returning the value associated with the key.</p>
<p>Returns <code>None</code> if the map does not contain the key. If there are
multiple values associated with the key, then the first one is returned.
See <code>remove_entry_mult</code> on <code>OccupiedEntry</code> for an API that yields all
values.</p>
<h1 id="examples-22" class="section-header"><a href="#examples-22">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello.world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">let</span> <span class="ident">prev</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">remove</span>(<span class="ident">HOST</span>).<span class="ident">unwrap</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="string">&quot;hello.world&quot;</span>, <span class="ident">prev</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">remove</span>(<span class="ident">HOST</span>).<span class="ident">is_none</span>());</pre>
</div></div>
<h2 id='implementations' class='small-section-header'>
Trait Implementations<a href='#implementations' class='anchor'></a>
</h2>
<div id='implementations-list'><h3 id='impl-IntoIterator' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html" title="trait core::iter::traits::IntoIterator">IntoIterator</a> for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code><a href='#impl-IntoIterator' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1656-1716' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='associatedtype.Item' class="type"><span id='Item.t' class='invisible'><code>type <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#associatedtype.Item' class="type">Item</a> = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a>&lt;<a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>&gt;, T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a></code></span></h4>
<div class='docblock'><p>The type of the elements being iterated over.</p>
</div><h4 id='associatedtype.IntoIter' class="type"><span id='IntoIter.t' class='invisible'><code>type <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#associatedtype.IntoIter' class="type">IntoIter</a> = <a class="struct" href="../../../actix_web/http/header/struct.IntoIter.html" title="struct actix_web::http::header::IntoIter">IntoIter</a>&lt;T&gt;</code></span></h4>
<div class='docblock'><p>Which kind of iterator are we turning this into?</p>
</div><h4 id='method.into_iter' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="../../../actix_web/http/header/struct.IntoIter.html" title="struct actix_web::http::header::IntoIter">IntoIter</a>&lt;T&gt;</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../../actix_web/http/header/struct.IntoIter.html" title="struct actix_web::http::header::IntoIter">IntoIter</a>&lt;T&gt;</h3><code class="content"><span class="where fmt-newline">impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> for <a class="struct" href="../../../actix_web/http/header/struct.IntoIter.html" title="struct actix_web::http::header::IntoIter">IntoIter</a>&lt;T&gt;</span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a>&lt;<a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>&gt;, T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>;</span></code></div></div><span id='into_iter.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#tymethod.into_iter' class='fnname'>into_iter</a>(self) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.IntoIter.html" title="struct actix_web::http::header::IntoIter">IntoIter</a>&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1709-1715' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Creates a consuming iterator, that is, one that moves keys and values
out of the map in arbitary order. The map cannot be used after calling
this.</p>
<p>For each yielded item that has <code>None</code> provided for the <code>HeaderName</code>,
then the associated header name is the same as that of the previously
yielded item. The first yielded item will have <code>HeaderName</code> set.</p>
<h1 id="examples-23" class="section-header"><a href="#examples-23">Examples</a></h1>
<p>Basic usage.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">header</span>::<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">header</span>::<span class="ident">CONTENT_TYPE</span>, <span class="string">&quot;json&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">into_iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="prelude-val">Some</span>(<span class="ident">header</span>::<span class="ident">CONTENT_LENGTH</span>), <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>())));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="prelude-val">Some</span>(<span class="ident">header</span>::<span class="ident">CONTENT_TYPE</span>), <span class="string">&quot;json&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>())));
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">is_none</span>());</pre>
<p>Multiple values per key.</p>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">header</span>::<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">header</span>::<span class="ident">CONTENT_LENGTH</span>, <span class="string">&quot;456&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">header</span>::<span class="ident">CONTENT_TYPE</span>, <span class="string">&quot;json&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">header</span>::<span class="ident">CONTENT_TYPE</span>, <span class="string">&quot;html&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">append</span>(<span class="ident">header</span>::<span class="ident">CONTENT_TYPE</span>, <span class="string">&quot;xml&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">iter</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">into_iter</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="prelude-val">Some</span>(<span class="ident">header</span>::<span class="ident">CONTENT_LENGTH</span>), <span class="string">&quot;123&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>())));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="prelude-val">None</span>, <span class="string">&quot;456&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>())));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="prelude-val">Some</span>(<span class="ident">header</span>::<span class="ident">CONTENT_TYPE</span>), <span class="string">&quot;json&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>())));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="prelude-val">None</span>, <span class="string">&quot;html&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>())));
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>(), <span class="prelude-val">Some</span>((<span class="prelude-val">None</span>, <span class="string">&quot;xml&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>())));
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">iter</span>.<span class="ident">next</span>().<span class="ident">is_none</span>());</pre>
</div></div><h3 id='impl-IntoIterator-1' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;'a, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html" title="trait core::iter::traits::IntoIterator">IntoIterator</a> for &amp;'a mut <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code><a href='#impl-IntoIterator-1' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1647-1654' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='associatedtype.Item-1' class="type"><span id='Item.t-1' class='invisible'><code>type <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#associatedtype.Item' class="type">Item</a> = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a>&amp;'a <a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a mut </a>T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a></code></span></h4>
<div class='docblock'><p>The type of the elements being iterated over.</p>
</div><h4 id='associatedtype.IntoIter-1' class="type"><span id='IntoIter.t-1' class='invisible'><code>type <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#associatedtype.IntoIter' class="type">IntoIter</a> = IterMut&lt;'a, T&gt;</code></span></h4>
<div class='docblock'><p>Which kind of iterator are we turning this into?</p>
</div><h4 id='method.into_iter-1' class="method"><span id='into_iter.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#tymethod.into_iter' class='fnname'>into_iter</a>(self) -&gt; IterMut&lt;'a, T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1651-1653' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Creates an iterator from a value. <a href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#tymethod.into_iter">Read more</a></p>
</div></div><h3 id='impl-IntoIterator-2' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;'a, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html" title="trait core::iter::traits::IntoIterator">IntoIterator</a> for &amp;'a <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code><a href='#impl-IntoIterator-2' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1638-1645' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='associatedtype.Item-2' class="type"><span id='Item.t-2' class='invisible'><code>type <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#associatedtype.Item' class="type">Item</a> = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a>&amp;'a <a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a </a>T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a></code></span></h4>
<div class='docblock'><p>The type of the elements being iterated over.</p>
</div><h4 id='associatedtype.IntoIter-2' class="type"><span id='IntoIter.t-2' class='invisible'><code>type <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#associatedtype.IntoIter' class="type">IntoIter</a> = <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;'a, T&gt;</code></span></h4>
<div class='docblock'><p>Which kind of iterator are we turning this into?</p>
</div><h4 id='method.into_iter-2' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;'a, T&gt;</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;'a, T&gt;</h3><code class="content"><span class="where fmt-newline">impl&lt;'a, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> for <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;'a, T&gt;</span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a>&amp;'a <a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a </a>T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>;</span></code></div></div><span id='into_iter.v-2' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#tymethod.into_iter' class='fnname'>into_iter</a>(self) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.Iter.html" title="struct actix_web::http::header::Iter">Iter</a>&lt;'a, T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1642-1644' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Creates an iterator from a value. <a href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html#tymethod.into_iter">Read more</a></p>
</div></div><h3 id='impl-FromIterator%3C(HeaderName%2C%20T)%3E' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.FromIterator.html" title="trait core::iter::traits::FromIterator">FromIterator</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>&gt; for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code><a href='#impl-FromIterator%3C(HeaderName%2C%20T)%3E' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1718-1727' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.from_iter' class="method"><span id='from_iter.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.FromIterator.html#tymethod.from_iter' class='fnname'>from_iter</a>&lt;I&gt;(iter: I) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;I: <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html" title="trait core::iter::traits::IntoIterator">IntoIterator</a>&lt;Item = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>&gt;,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1720-1726' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Creates a value from an iterator. <a href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.FromIterator.html#tymethod.from_iter">Read more</a></p>
</div></div><h3 id='impl-Debug' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a> for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html" title="trait core::fmt::Debug">Debug</a>,&nbsp;</span></code><a href='#impl-Debug' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1850-1854' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&amp;self, f: &amp;mut <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html" title="struct core::fmt::Formatter">Formatter</a>) -&gt; <a class="enum" href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html" title="enum core::result::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>, <a class="struct" href="https://doc.rust-lang.org/nightly/core/fmt/struct.Error.html" title="struct core::fmt::Error">Error</a>&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1851-1853' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Formats the value using the given formatter. <a href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p>
</div></div><h3 id='impl-Eq' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/cmp/trait.Eq.html" title="trait core::cmp::Eq">Eq</a> for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/cmp/trait.Eq.html" title="trait core::cmp::Eq">Eq</a>,&nbsp;</span></code><a href='#impl-Eq' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1848' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'></div><h3 id='impl-Default' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/default/trait.Default.html" title="trait core::default::Default">Default</a> for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code><a href='#impl-Default' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1856-1860' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.default' class="method"><span id='default.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/default/trait.Default.html#tymethod.default' class='fnname'>default</a>() -&gt; <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1857-1859' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns the &quot;default value&quot; for a type. <a href="https://doc.rust-lang.org/nightly/core/default/trait.Default.html#tymethod.default">Read more</a></p>
</div></div><h3 id='impl-PartialEq%3CHeaderMap%3CT%3E%3E' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html" title="trait core::cmp::PartialEq">PartialEq</a>&lt;<a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;&gt; for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html" title="trait core::cmp::PartialEq">PartialEq</a>&lt;T&gt;,&nbsp;</span></code><a href='#impl-PartialEq%3CHeaderMap%3CT%3E%3E' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1836-1846' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.eq' class="method"><span id='eq.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#tymethod.eq' class='fnname'>eq</a>(&amp;self, other: &amp;<a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1837-1845' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>This method tests for <code>self</code> and <code>other</code> values to be equal, and is used by <code>==</code>. <a href="https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#tymethod.eq">Read more</a></p>
</div><h4 id='method.ne' class="method"><span id='ne.v' class='invisible'><table class='table-display'><tbody><tr><td><code><div class="docblock attributes">#[must_use]
</div>fn <a href='https://doc.rust-lang.org/nightly/core/cmp/trait.PartialEq.html#method.ne' class='fnname'>ne</a>(&amp;self, other: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;</a>Rhs) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.bool.html">bool</a></code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.0.0'>1.0.0</div><a class='srclink' href='https://doc.rust-lang.org/nightly/src/core/cmp.rs.html#126' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>This method tests for <code>!=</code>.</p>
</div></div><h3 id='impl-Extend%3C(HeaderName%2C%20T)%3E' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.Extend.html" title="trait core::iter::traits::Extend">Extend</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>&gt; for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code><a href='#impl-Extend%3C(HeaderName%2C%20T)%3E' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1813-1834' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.extend' class="method"><span id='extend.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.Extend.html#tymethod.extend' class='fnname'>extend</a>&lt;I&gt;(&amp;mut self, iter: I) <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;I: <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html" title="trait core::iter::traits::IntoIterator">IntoIterator</a>&lt;Item = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>, T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>&gt;,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1815-1833' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Extends a collection with the contents of an iterator. <a href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.Extend.html#tymethod.extend">Read more</a></p>
</div></div><h3 id='impl-Extend%3C(Option%3CHeaderName%3E%2C%20T)%3E' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.Extend.html" title="trait core::iter::traits::Extend">Extend</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a>&lt;<a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>&gt;, T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>&gt; for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code><a href='#impl-Extend%3C(Option%3CHeaderName%3E%2C%20T)%3E' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1729-1811' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.extend-1' class="method"><span id='extend.v-1' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/iter/traits/trait.Extend.html#tymethod.extend' class='fnname'>extend</a>&lt;I&gt;(&amp;mut self, iter: I) <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;I: <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/traits/trait.IntoIterator.html" title="trait core::iter::traits::IntoIterator">IntoIterator</a>&lt;Item = <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">(</a><a class="enum" href="https://doc.rust-lang.org/nightly/core/option/enum.Option.html" title="enum core::option::Option">Option</a>&lt;<a class="struct" href="../../../actix_web/http/header/struct.HeaderName.html" title="struct actix_web::http::header::HeaderName">HeaderName</a>&gt;, T<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.tuple.html">)</a>&gt;,&nbsp;</span></code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1766-1810' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Extend a <code>HeaderMap</code> with the contents of another <code>HeaderMap</code>.</p>
<p>This function expects the yielded items to follow the same structure as
<code>IntoIter</code>.</p>
<h1 id="panics-1" class="section-header"><a href="#panics-1">Panics</a></h1>
<p>This panics if the first yielded item does not have a <code>HeaderName</code>.</p>
<h1 id="examples-24" class="section-header"><a href="#examples-24">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">ACCEPT</span>, <span class="string">&quot;text/plain&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;hello.world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">extra</span> <span class="op">=</span> <span class="ident">HeaderMap</span>::<span class="ident">new</span>();
<span class="ident">extra</span>.<span class="ident">insert</span>(<span class="ident">HOST</span>, <span class="string">&quot;foo.bar&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">extra</span>.<span class="ident">insert</span>(<span class="ident">COOKIE</span>, <span class="string">&quot;hello&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">extra</span>.<span class="ident">append</span>(<span class="ident">COOKIE</span>, <span class="string">&quot;world&quot;</span>.<span class="ident">parse</span>().<span class="ident">unwrap</span>());
<span class="ident">map</span>.<span class="ident">extend</span>(<span class="ident">extra</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">&quot;host&quot;</span>], <span class="string">&quot;foo.bar&quot;</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">&quot;accept&quot;</span>], <span class="string">&quot;text/plain&quot;</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">&quot;cookie&quot;</span>], <span class="string">&quot;hello&quot;</span>);
<span class="kw">let</span> <span class="ident">v</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_all</span>(<span class="string">&quot;host&quot;</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">1</span>, <span class="ident">v</span>.<span class="ident">iter</span>().<span class="ident">count</span>());
<span class="kw">let</span> <span class="ident">v</span> <span class="op">=</span> <span class="ident">map</span>.<span class="ident">get_all</span>(<span class="string">&quot;cookie&quot;</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="number">2</span>, <span class="ident">v</span>.<span class="ident">iter</span>().<span class="ident">count</span>());</pre>
</div></div><h3 id='impl-Clone' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a> for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html" title="trait core::clone::Clone">Clone</a>,&nbsp;</span></code><a href='#impl-Clone' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#38' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='method.clone' class="method"><span id='clone.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#tymethod.clone' class='fnname'>clone</a>(&amp;self) -&gt; <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt;</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#38' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Returns a copy of the value. <a href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#tymethod.clone">Read more</a></p>
</div><h4 id='method.clone_from' class="method"><span id='clone_from.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#method.clone_from' class='fnname'>clone_from</a>(&amp;mut self, source: <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;</a>Self)</code></span></td><td><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.0.0'>1.0.0</div><a class='srclink' href='https://doc.rust-lang.org/nightly/src/core/clone.rs.html#130-132' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Performs copy-assignment from <code>source</code>. <a href="https://doc.rust-lang.org/nightly/core/clone/trait.Clone.html#method.clone_from">Read more</a></p>
</div></div><h3 id='impl-Index%3CK%3E' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;'a, K, T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html" title="trait core::ops::index::Index">Index</a>&lt;K&gt; for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;K: <a class="trait" href="../../../actix_web/http/header/trait.AsHeaderName.html" title="trait actix_web::http::header::AsHeaderName">AsHeaderName</a>,&nbsp;</span></code><a href='#impl-Index%3CK%3E' class='anchor'></a></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1862-1871' title='goto source code'>[src]</a></span></td></tr></tbody></table></h3><div class='impl-items'><h4 id='associatedtype.Output' class="type"><span id='Output.t' class='invisible'><code>type <a href='https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html#associatedtype.Output' class="type">Output</a> = T</code></span></h4>
<div class='docblock'><p>The returned type after indexing.</p>
</div><h4 id='method.index' class="method"><div class="important-traits"><div class='tooltip'>ⓘ<span class='tooltiptext'>Important traits for <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a mut </a>R</span></div><div class="content hidden"><h3 class="important">Important traits for <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a mut </a>R</h3><code class="content"><span class="where fmt-newline">impl&lt;'a, R&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html" title="trait std::io::Read">Read</a> for <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a mut </a>R <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;R: <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Read.html" title="trait std::io::Read">Read</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,&nbsp;</span></span><span class="where fmt-newline">impl&lt;'a, W&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Write.html" title="trait std::io::Write">Write</a> for <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a mut </a>W <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;W: <a class="trait" href="https://doc.rust-lang.org/nightly/std/io/trait.Write.html" title="trait std::io::Write">Write</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,&nbsp;</span></span><span class="where fmt-newline">impl&lt;'a, I&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> for <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;'a mut </a>I <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;I: <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a> + ?<a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html" title="trait core::marker::Sized">Sized</a>,&nbsp;</span></span><span class="where fmt-newline"> type <a href='https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item' class="type">Item</a> = &lt;I as <a class="trait" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html" title="trait core::iter::iterator::Iterator">Iterator</a>&gt;::<a class="type" href="https://doc.rust-lang.org/nightly/core/iter/iterator/trait.Iterator.html#associatedtype.Item" title="type core::iter::iterator::Iterator::Item">Item</a>;</span></code></div></div><span id='index.v' class='invisible'><table class='table-display'><tbody><tr><td><code>fn <a href='https://doc.rust-lang.org/nightly/core/ops/index/trait.Index.html#tymethod.index' class='fnname'>index</a>(&amp;self, index: K) -&gt; <a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&amp;</a>T</code></span></td><td><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='https://docs.rs/http/0.1.7/src/http/header/map.rs.html#1868-1870' title='goto source code'>[src]</a></td></tr></tbody></table></span></h4><div class='docblock'><p>Performs the indexing (<code>container[index]</code>) operation.</p>
</div></div></div>
<h2 id='synthetic-implementations' class='small-section-header'>
Auto Trait Implementations<a href='#synthetic-implementations' class='anchor'></a>
</h2>
<div id='synthetic-implementations-list'>
<h3 id='impl-Send' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a> for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Send.html" title="trait core::marker::Send">Send</a>,&nbsp;</span></code><a href='#impl-Send' class='anchor'></a></span></td><td><span class='out-of-band'></span></td></tr></tbody></table></h3><div class='impl-items'></div><h3 id='impl-Sync' class='impl'><span class='in-band'><table class='table-display'><tbody><tr><td><code>impl&lt;T&gt; <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sync.html" title="trait core::marker::Sync">Sync</a> for <a class="struct" href="../../../actix_web/http/header/struct.HeaderMap.html" title="struct actix_web::http::header::HeaderMap">HeaderMap</a>&lt;T&gt; <span class="where fmt-newline">where<br>&nbsp;&nbsp;&nbsp;&nbsp;T: <a class="trait" href="https://doc.rust-lang.org/nightly/core/marker/trait.Sync.html" title="trait core::marker::Sync">Sync</a>,&nbsp;</span></code><a href='#impl-Sync' class='anchor'></a></span></td><td><span class='out-of-band'></span></td></tr></tbody></table></h3><div class='impl-items'></div></div></section><section id="search" class="content hidden"></section><section class="footer"></section><aside id="help" class="hidden"><div><h1 class="hidden">Help</h1><div class="shortcuts"><h2>Keyboard Shortcuts</h2><dl><dt><kbd>?</kbd></dt><dd>Show this help dialog</dd><dt><kbd>S</kbd></dt><dd>Focus the search field</dd><dt><kbd>↑</kbd></dt><dd>Move up in search results</dd><dt><kbd>↓</kbd></dt><dd>Move down in search results</dd><dt><kbd>↹</kbd></dt><dd>Switch tab</dd><dt><kbd>&#9166;</kbd></dt><dd>Go to active search result</dd><dt><kbd>+</kbd></dt><dd>Expand all sections</dd><dt><kbd>-</kbd></dt><dd>Collapse all sections</dd></dl></div><div class="infos"><h2>Search Tricks</h2><p>Prefix searches with a type followed by a colon (e.g. <code>fn:</code>) to restrict the search to a given type.</p><p>Accepted types are: <code>fn</code>, <code>mod</code>, <code>struct</code>, <code>enum</code>, <code>trait</code>, <code>type</code>, <code>macro</code>, and <code>const</code>.</p><p>Search functions by type signature (e.g. <code>vec -> usize</code> or <code>* -> vec</code>)</p><p>Search multiple things at once by splitting your query with comma (e.g. <code>str,u8</code> or <code>String,struct:Vec,test</code>)</p></div></div></aside><script>window.rootPath = "../../../";window.currentCrate = "actix_web";</script><script src="../../../aliases.js"></script><script src="../../../main.js"></script><script defer src="../../../search-index.js"></script></body></html>
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