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<p class='location'>Enum Entry</p><div class="sidebar-elems"><div class="block items"><a class="sidebar-title" href="#variants">Variants</a><div class="sidebar-links"><a href="#variant.Vacant">Vacant</a><a href="#variant.Occupied">Occupied</a></div><a class="sidebar-title" href="#methods">Methods</a><div class="sidebar-links"><a href="#method.or_insert">or_insert</a><a href="#method.or_insert_with">or_insert_with</a><a href="#method.key">key</a><a href="#method.and_modify">and_modify</a><a href="#method.or_default">or_default</a></div><a class="sidebar-title" href="#implementations">Trait Implementations</a><div class="sidebar-links"><a href="#impl-Debug">Debug</a></div></div><p class='location'><a href='../index.html'>alloc</a>::<wbr><a href='index.html'>btree_map</a></p><script>window.sidebarCurrent = {name: 'Entry', ty: 'enum', relpath: ''};</script><script defer src="sidebar-items.js"></script></div>
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<h1 class='fqn'><span class='in-band'>Enum <a href='../index.html'>alloc</a>::<wbr><a href='index.html'>btree_map</a>::<wbr><a class="enum" href=''>Entry</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'>
<a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">
[<span class='inner'>−</span>]
</a>
</span><a class='srclink' href='../../src/alloc/btree/map.rs.html#429-439' title='goto source code'>[src]</a></span></h1>
<pre class='rust enum'>pub enum Entry<'a, K: 'a, V: 'a> {
Vacant(<a class="struct" href="../../alloc/btree_map/struct.VacantEntry.html" title="struct alloc::btree_map::VacantEntry">VacantEntry</a><'a, K, V>),
Occupied(<a class="struct" href="../../alloc/btree_map/struct.OccupiedEntry.html" title="struct alloc::btree_map::OccupiedEntry">OccupiedEntry</a><'a, K, V>),
}</pre><div class='docblock'><p>A view into a single entry in a map, which may either be vacant or occupied.</p>
<p>This <code>enum</code> is constructed from the <a href="struct.BTreeMap.html#method.entry"><code>entry</code></a> method on <a href="struct.BTreeMap.html"><code>BTreeMap</code></a>.</p>
</div><h2 id='variants' class='variants small-section-header'>
Variants<a href='#variants' class='anchor'></a></h2>
<span id="variant.Vacant" class="variant small-section-header"><a href="#variant.Vacant" class="anchor field"></a><span id='Vacant.v' class='invisible'><code>Vacant(<a class="struct" href="../../alloc/btree_map/struct.VacantEntry.html" title="struct alloc::btree_map::VacantEntry">VacantEntry</a><'a, K, V>)</code></span></span><div class='docblock'><p>A vacant entry.</p>
</div><span id="variant.Occupied" class="variant small-section-header"><a href="#variant.Occupied" class="anchor field"></a><span id='Occupied.v' class='invisible'><code>Occupied(<a class="struct" href="../../alloc/btree_map/struct.OccupiedEntry.html" title="struct alloc::btree_map::OccupiedEntry">OccupiedEntry</a><'a, K, V>)</code></span></span><div class='docblock'><p>An occupied entry.</p>
</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'><code>impl<'a, K: <a class="trait" href="../../core/cmp/trait.Ord.html" title="trait core::cmp::Ord">Ord</a>, V> <a class="enum" href="../../alloc/btree_map/enum.Entry.html" title="enum alloc::btree_map::Entry">Entry</a><'a, K, V></code><a href='#impl' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/alloc/btree/map.rs.html#2048-2144' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.or_insert' class="method"><span id='or_insert.v' class='invisible'><code>pub fn <a href='#method.or_insert' class='fnname'>or_insert</a>(self, default: V) -> &'a mut V</code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/alloc/btree/map.rs.html#2063-2068' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Ensures a value is in the entry by inserting the default if empty, and returns
a mutable reference to the value in the entry.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">BTreeMap</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span>: <span class="ident">BTreeMap</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="ident">usize</span><span class="op">></span> <span class="op">=</span> <span class="ident">BTreeMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">entry</span>(<span class="string">"poneyland"</span>).<span class="ident">or_insert</span>(<span class="number">12</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">"poneyland"</span>], <span class="number">12</span>);</pre>
</div><h4 id='method.or_insert_with' class="method"><span id='or_insert_with.v' class='invisible'><code>pub fn <a href='#method.or_insert_with' class='fnname'>or_insert_with</a><F: <a class="trait" href="../../core/ops/function/trait.FnOnce.html" title="trait core::ops::function::FnOnce">FnOnce</a>() -> V>(self, default: F) -> &'a mut V</code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/alloc/btree/map.rs.html#2086-2091' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Ensures a value is in the entry by inserting the result of the default function if empty,
and returns a mutable reference to the value in the entry.</p>
<h1 id="examples-1" class="section-header"><a href="#examples-1">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">BTreeMap</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span>: <span class="ident">BTreeMap</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="ident">String</span><span class="op">></span> <span class="op">=</span> <span class="ident">BTreeMap</span>::<span class="ident">new</span>();
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="string">"hoho"</span>.<span class="ident">to_string</span>();
<span class="ident">map</span>.<span class="ident">entry</span>(<span class="string">"poneyland"</span>).<span class="ident">or_insert_with</span>(<span class="op">||</span> <span class="ident">s</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">"poneyland"</span>], <span class="string">"hoho"</span>.<span class="ident">to_string</span>());</pre>
</div><h4 id='method.key' class="method"><span id='key.v' class='invisible'><code>pub fn <a href='#method.key' class='fnname'>key</a>(&self) -> &K</code></span><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.10.0'>1.10.0</div><a class='srclink' href='../../src/alloc/btree/map.rs.html#2104-2109' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Returns a reference to this entry's key.</p>
<h1 id="examples-2" class="section-header"><a href="#examples-2">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">BTreeMap</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span>: <span class="ident">BTreeMap</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="ident">usize</span><span class="op">></span> <span class="op">=</span> <span class="ident">BTreeMap</span>::<span class="ident">new</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>.<span class="ident">entry</span>(<span class="string">"poneyland"</span>).<span class="ident">key</span>(), <span class="kw-2">&</span><span class="string">"poneyland"</span>);</pre>
</div><h4 id='method.and_modify' class="method"><span id='and_modify.v' class='invisible'><code>pub fn <a href='#method.and_modify' class='fnname'>and_modify</a><F>(self, f: F) -> Self <span class="where fmt-newline">where<br> F: <a class="trait" href="../../core/ops/function/trait.FnMut.html" title="trait core::ops::function::FnMut">FnMut</a>(&mut V), </span></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/alloc/btree/map.rs.html#2133-2143' title='goto source code'>[src]</a></span></h4>
<div class='stability'><div class='stab unstable'><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>entry_and_modify </code><a href="https://github.com/rust-lang/rust/issues/44733">#44733</a>)</div></div><div class='docblock'><p>Provides in-place mutable access to an occupied entry before any
potential inserts into the map.</p>
<h1 id="examples-3" class="section-header"><a href="#examples-3">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="attribute">#![<span class="ident">feature</span>(<span class="ident">entry_and_modify</span>)]</span>
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">BTreeMap</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span>: <span class="ident">BTreeMap</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="ident">usize</span><span class="op">></span> <span class="op">=</span> <span class="ident">BTreeMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">entry</span>(<span class="string">"poneyland"</span>)
.<span class="ident">and_modify</span>(<span class="op">|</span><span class="ident">e</span><span class="op">|</span> { <span class="kw-2">*</span><span class="ident">e</span> <span class="op">+=</span> <span class="number">1</span> })
.<span class="ident">or_insert</span>(<span class="number">42</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">"poneyland"</span>], <span class="number">42</span>);
<span class="ident">map</span>.<span class="ident">entry</span>(<span class="string">"poneyland"</span>)
.<span class="ident">and_modify</span>(<span class="op">|</span><span class="ident">e</span><span class="op">|</span> { <span class="kw-2">*</span><span class="ident">e</span> <span class="op">+=</span> <span class="number">1</span> })
.<span class="ident">or_insert</span>(<span class="number">42</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">"poneyland"</span>], <span class="number">43</span>);</pre>
</div></div><h3 id='impl-1' class='impl'><span class='in-band'><code>impl<'a, K: <a class="trait" href="../../core/cmp/trait.Ord.html" title="trait core::cmp::Ord">Ord</a>, V: <a class="trait" href="../../core/default/trait.Default.html" title="trait core::default::Default">Default</a>> <a class="enum" href="../../alloc/btree_map/enum.Entry.html" title="enum alloc::btree_map::Entry">Entry</a><'a, K, V></code><a href='#impl-1' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/alloc/btree/map.rs.html#2146-2171' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.or_default' class="method"><span id='or_default.v' class='invisible'><code>pub fn <a href='#method.or_default' class='fnname'>or_default</a>(self) -> &'a mut V</code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/alloc/btree/map.rs.html#2164-2169' title='goto source code'>[src]</a></span></h4>
<div class='stability'><div class='stab unstable'><span class=microscope>🔬</span> This is a nightly-only experimental API. (<code>entry_or_default </code><a href="https://github.com/rust-lang/rust/issues/44324">#44324</a>)</div></div><div class='docblock'><p>Ensures a value is in the entry by inserting the default value if empty,
and returns a mutable reference to the value in the entry.</p>
<h1 id="examples-4" class="section-header"><a href="#examples-4">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="attribute">#![<span class="ident">feature</span>(<span class="ident">entry_or_default</span>)]</span>
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">BTreeMap</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">map</span>: <span class="ident">BTreeMap</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">str</span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">>></span> <span class="op">=</span> <span class="ident">BTreeMap</span>::<span class="ident">new</span>();
<span class="ident">map</span>.<span class="ident">entry</span>(<span class="string">"poneyland"</span>).<span class="ident">or_default</span>();
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">map</span>[<span class="string">"poneyland"</span>], <span class="prelude-val">None</span>);</pre>
</div></div>
<h2 id='implementations' class='small-section-header'>
Trait Implementations<a href='#implementations' class='anchor'></a>
</h2>
<h3 id='impl-Debug' class='impl'><span class='in-band'><code>impl<'a, K: 'a + <a class="trait" href="../../alloc/fmt/trait.Debug.html" title="trait alloc::fmt::Debug">Debug</a> + <a class="trait" href="../../core/cmp/trait.Ord.html" title="trait core::cmp::Ord">Ord</a>, V: 'a + <a class="trait" href="../../alloc/fmt/trait.Debug.html" title="trait alloc::fmt::Debug">Debug</a>> <a class="trait" href="../../alloc/fmt/trait.Debug.html" title="trait alloc::fmt::Debug">Debug</a> for <a class="enum" href="../../alloc/btree_map/enum.Entry.html" title="enum alloc::btree_map::Entry">Entry</a><'a, K, V></code><a href='#impl-Debug' class='anchor'></a></span><span class='out-of-band'><div class='ghost'></div><div class='since' title='Stable since Rust version 1.12.0'>1.12.0</div><a class='srclink' href='../../src/alloc/btree/map.rs.html#442-453' title='goto source code'>[src]</a></span></h3>
<div class='impl-items'><h4 id='method.fmt' class="method"><span id='fmt.v' class='invisible'><code>fn <a href='../../alloc/fmt/trait.Debug.html#tymethod.fmt' class='fnname'>fmt</a>(&self, f: &mut <a class="struct" href="../../alloc/fmt/struct.Formatter.html" title="struct alloc::fmt::Formatter">Formatter</a>) -> <a class="type" href="../../alloc/fmt/type.Result.html" title="type alloc::fmt::Result">Result</a></code></span><span class='out-of-band'><div class='ghost'></div><a class='srclink' href='../../src/alloc/btree/map.rs.html#443-452' title='goto source code'>[src]</a></span></h4>
<div class='docblock'><p>Formats the value using the given formatter. <a href="../../alloc/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p>
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