| <!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="A view into a single entry in a map, which may either be vacant or occupied, with any borrowed form of the map’s key type."><meta name="keywords" content="rust, rustlang, rust-lang, EntryRef"><title>EntryRef in hashbrown::hash_map - Rust</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" 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class="sidebar-menu-toggle">☰</button><a class="sidebar-logo" href="../../hashbrown/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2></h2></nav><nav class="sidebar"><a class="sidebar-logo" href="../../hashbrown/index.html"><div class="logo-container"><img class="rust-logo" src="../../rust-logo.svg" alt="logo"></div></a><h2 class="location"><a href="#">EntryRef</a></h2><div class="sidebar-elems"><section><h3><a href="#variants">Variants</a></h3><ul class="block"><li><a href="#variant.Occupied">Occupied</a></li><li><a href="#variant.Vacant">Vacant</a></li></ul><h3><a href="#implementations">Methods</a></h3><ul class="block"><li><a href="#method.and_modify">and_modify</a></li><li><a href="#method.and_replace_entry_with">and_replace_entry_with</a></li><li><a href="#method.insert">insert</a></li><li><a href="#method.key">key</a></li><li><a href="#method.or_default">or_default</a></li><li><a href="#method.or_insert">or_insert</a></li><li><a href="#method.or_insert_with">or_insert_with</a></li><li><a href="#method.or_insert_with_key">or_insert_with_key</a></li></ul><h3><a href="#trait-implementations">Trait Implementations</a></h3><ul class="block"><li><a href="#impl-Debug-for-EntryRef%3C%27_%2C%20%27_%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">Debug</a></li></ul><h3><a href="#synthetic-implementations">Auto Trait Implementations</a></h3><ul class="block"><li><a href="#impl-RefUnwindSafe-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">RefUnwindSafe</a></li><li><a href="#impl-Send-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">Send</a></li><li><a href="#impl-Sync-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">Sync</a></li><li><a href="#impl-Unpin-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">Unpin</a></li><li><a href="#impl-UnwindSafe-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">!UnwindSafe</a></li></ul><h3><a href="#blanket-implementations">Blanket Implementations</a></h3><ul class="block"><li><a href="#impl-Any-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">Any</a></li><li><a href="#impl-Borrow%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">Borrow<T></a></li><li><a href="#impl-BorrowMut%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">BorrowMut<T></a></li><li><a href="#impl-From%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">From<T></a></li><li><a href="#impl-Into%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">Into<U></a></li><li><a href="#impl-TryFrom%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">TryFrom<U></a></li><li><a href="#impl-TryInto%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E">TryInto<U></a></li></ul></section><h2><a href="index.html">In hashbrown::hash_map</a></h2></div></nav><main><div class="width-limiter"><nav class="sub"><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="main-heading"><h1 class="fqn">Enum <a href="../index.html">hashbrown</a>::<wbr><a href="index.html">hash_map</a>::<wbr><a class="enum" href="#">EntryRef</a><button id="copy-path" onclick="copy_path(this)" title="Copy item path to clipboard"><img src="../../clipboard.svg" width="19" height="18" alt="Copy item path"></button></h1><span class="out-of-band"><a class="srclink" href="../../src/hashbrown/map.rs.html#4321-4354">source</a> · <a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class="inner">−</span>]</a></span></div><div class="item-decl"><pre class="rust enum"><code>pub enum EntryRef<'a, 'b, K, Q: ?Sized, V, S, A = Global><span class="where fmt-newline">where<br> A: Allocator + Clone,</span>{ |
| Occupied(<a class="struct" href="struct.OccupiedEntryRef.html" title="struct hashbrown::hash_map::OccupiedEntryRef">OccupiedEntryRef</a><'a, 'b, K, Q, V, S, A>), |
| Vacant(<a class="struct" href="struct.VacantEntryRef.html" title="struct hashbrown::hash_map::VacantEntryRef">VacantEntryRef</a><'a, 'b, K, Q, V, S, A>), |
| }</code></pre></div><details class="rustdoc-toggle top-doc" open><summary class="hideme"><span>Expand description</span></summary><div class="docblock"><p>A view into a single entry in a map, which may either be vacant or occupied, |
| with any borrowed form of the map’s key type.</p> |
| <p>This <code>enum</code> is constructed from the <a href="struct.HashMap.html#method.entry_ref"><code>entry_ref</code></a> method on <a href="struct.HashMap.html"><code>HashMap</code></a>.</p> |
| <p><a href="https://doc.rust-lang.org/std/hash/trait.Hash.html"><code>Hash</code></a> and <a href="https://doc.rust-lang.org/std/cmp/trait.Eq.html"><code>Eq</code></a> on the borrowed form of the map’s key type <em>must</em> match those |
| for the key type. It also require that key may be constructed from the borrowed |
| form through the <a href="https://doc.rust-lang.org/std/convert/trait.From.html"><code>From</code></a> trait.</p> |
| <h2 id="examples"><a href="#examples">Examples</a></h2> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::hash_map::{EntryRef, HashMap, OccupiedEntryRef}; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map = HashMap::new(); |
| map.extend([(<span class="string">"a"</span>.to_owned(), <span class="number">10</span>), (<span class="string">"b"</span>.into(), <span class="number">20</span>), (<span class="string">"c"</span>.into(), <span class="number">30</span>)]); |
| <span class="macro">assert_eq!</span>(map.len(), <span class="number">3</span>); |
| |
| <span class="comment">// Existing key (insert) |
| </span><span class="kw">let </span>key = String::from(<span class="string">"a"</span>); |
| <span class="kw">let </span>entry: EntryRef<<span class="kw">_</span>, <span class="kw">_</span>, <span class="kw">_</span>, <span class="kw">_</span>> = map.entry_ref(<span class="kw-2">&</span>key); |
| <span class="kw">let </span>_raw_o: OccupiedEntryRef<<span class="kw">_</span>, <span class="kw">_</span>, <span class="kw">_</span>, <span class="kw">_</span>> = entry.insert(<span class="number">1</span>); |
| <span class="macro">assert_eq!</span>(map.len(), <span class="number">3</span>); |
| <span class="comment">// Nonexistent key (insert) |
| </span>map.entry_ref(<span class="string">"d"</span>).insert(<span class="number">4</span>); |
| |
| <span class="comment">// Existing key (or_insert) |
| </span><span class="kw">let </span>v = map.entry_ref(<span class="string">"b"</span>).or_insert(<span class="number">2</span>); |
| <span class="macro">assert_eq!</span>(std::mem::replace(v, <span class="number">2</span>), <span class="number">20</span>); |
| <span class="comment">// Nonexistent key (or_insert) |
| </span>map.entry_ref(<span class="string">"e"</span>).or_insert(<span class="number">5</span>); |
| |
| <span class="comment">// Existing key (or_insert_with) |
| </span><span class="kw">let </span>v = map.entry_ref(<span class="string">"c"</span>).or_insert_with(|| <span class="number">3</span>); |
| <span class="macro">assert_eq!</span>(std::mem::replace(v, <span class="number">3</span>), <span class="number">30</span>); |
| <span class="comment">// Nonexistent key (or_insert_with) |
| </span>map.entry_ref(<span class="string">"f"</span>).or_insert_with(|| <span class="number">6</span>); |
| |
| <span class="macro">println!</span>(<span class="string">"Our HashMap: {:?}"</span>, map); |
| |
| <span class="kw">for </span>(key, value) <span class="kw">in </span>[<span class="string">"a"</span>, <span class="string">"b"</span>, <span class="string">"c"</span>, <span class="string">"d"</span>, <span class="string">"e"</span>, <span class="string">"f"</span>].into_iter().zip(<span class="number">1</span>..=<span class="number">6</span>) { |
| <span class="macro">assert_eq!</span>(map[key], value) |
| } |
| <span class="macro">assert_eq!</span>(map.len(), <span class="number">6</span>);</code></pre></div> |
| </div></details><h2 id="variants" class="variants small-section-header">Variants<a href="#variants" class="anchor"></a></h2><h3 id="variant.Occupied" class="variant small-section-header"><a href="#variant.Occupied" class="anchor field"></a><code>Occupied(<a class="struct" href="struct.OccupiedEntryRef.html" title="struct hashbrown::hash_map::OccupiedEntryRef">OccupiedEntryRef</a><'a, 'b, K, Q, V, S, A>)</code></h3><div class="docblock"><p>An occupied entry.</p> |
| <h4 id="examples-1"><a href="#examples-1">Examples</a></h4> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::hash_map::{EntryRef, HashMap}; |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<<span class="kw">_</span>, <span class="kw">_</span>> = [(<span class="string">"a"</span>.to_owned(), <span class="number">100</span>), (<span class="string">"b"</span>.into(), <span class="number">200</span>)].into(); |
| |
| <span class="kw">match </span>map.entry_ref(<span class="string">"a"</span>) { |
| EntryRef::Vacant(<span class="kw">_</span>) => <span class="macro">unreachable!</span>(), |
| EntryRef::Occupied(<span class="kw">_</span>) => { } |
| }</code></pre></div> |
| </div><h3 id="variant.Vacant" class="variant small-section-header"><a href="#variant.Vacant" class="anchor field"></a><code>Vacant(<a class="struct" href="struct.VacantEntryRef.html" title="struct hashbrown::hash_map::VacantEntryRef">VacantEntryRef</a><'a, 'b, K, Q, V, S, A>)</code></h3><div class="docblock"><p>A vacant entry.</p> |
| <h4 id="examples-2"><a href="#examples-2">Examples</a></h4> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::hash_map::{EntryRef, HashMap}; |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, i32> = HashMap::new(); |
| |
| <span class="kw">match </span>map.entry_ref(<span class="string">"a"</span>) { |
| EntryRef::Occupied(<span class="kw">_</span>) => <span class="macro">unreachable!</span>(), |
| EntryRef::Vacant(<span class="kw">_</span>) => { } |
| }</code></pre></div> |
| </div><h2 id="implementations" class="small-section-header">Implementations<a href="#implementations" class="anchor"></a></h2><div id="implementations-list"><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5595-5844">source</a><a href="#impl-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<'a, 'b, K, Q: ?Sized, V, S, A: Allocator + Clone> <a class="enum" href="enum.EntryRef.html" title="enum hashbrown::hash_map::EntryRef">EntryRef</a><'a, 'b, K, Q, V, S, A></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.insert" class="method has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5609-5621">source</a><h4 class="code-header">pub fn <a href="#method.insert" class="fnname">insert</a>(self, value: V) -> <a class="struct" href="struct.OccupiedEntryRef.html" title="struct hashbrown::hash_map::OccupiedEntryRef">OccupiedEntryRef</a><'a, 'b, K, Q, V, S, A><span class="where fmt-newline">where<br> K: Hash + From<&'b Q>,<br> S: BuildHasher,</span></h4></section></summary><div class="docblock"><p>Sets the value of the entry, and returns an OccupiedEntryRef.</p> |
| <h5 id="examples-3"><a href="#examples-3">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::HashMap; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, u32> = HashMap::new(); |
| <span class="kw">let </span>entry = map.entry_ref(<span class="string">"horseyland"</span>).insert(<span class="number">37</span>); |
| |
| <span class="macro">assert_eq!</span>(entry.key(), <span class="string">"horseyland"</span>);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.or_insert" class="method has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5642-5651">source</a><h4 class="code-header">pub fn <a href="#method.or_insert" class="fnname">or_insert</a>(self, default: V) -> &'a mut V<span class="where fmt-newline">where<br> K: Hash + From<&'b Q>,<br> S: BuildHasher,</span></h4></section></summary><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> |
| <h5 id="examples-4"><a href="#examples-4">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::HashMap; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, u32> = HashMap::new(); |
| |
| <span class="comment">// nonexistent key |
| </span>map.entry_ref(<span class="string">"poneyland"</span>).or_insert(<span class="number">3</span>); |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">3</span>); |
| |
| <span class="comment">// existing key |
| </span><span class="kw-2">*</span>map.entry_ref(<span class="string">"poneyland"</span>).or_insert(<span class="number">10</span>) <span class="kw-2">*</span>= <span class="number">2</span>; |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">6</span>);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.or_insert_with" class="method has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5672-5681">source</a><h4 class="code-header">pub fn <a href="#method.or_insert_with" class="fnname">or_insert_with</a><F: FnOnce() -> V>(self, default: F) -> &'a mut V<span class="where fmt-newline">where<br> K: Hash + From<&'b Q>,<br> S: BuildHasher,</span></h4></section></summary><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> |
| <h5 id="examples-5"><a href="#examples-5">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::HashMap; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, u32> = HashMap::new(); |
| |
| <span class="comment">// nonexistent key |
| </span>map.entry_ref(<span class="string">"poneyland"</span>).or_insert_with(|| <span class="number">3</span>); |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">3</span>); |
| |
| <span class="comment">// existing key |
| </span><span class="kw-2">*</span>map.entry_ref(<span class="string">"poneyland"</span>).or_insert_with(|| <span class="number">10</span>) <span class="kw-2">*</span>= <span class="number">2</span>; |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">6</span>);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.or_insert_with_key" class="method has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5706-5718">source</a><h4 class="code-header">pub fn <a href="#method.or_insert_with_key" class="fnname">or_insert_with_key</a><F: FnOnce(&Q) -> V>(self, default: F) -> &'a mut V<span class="where fmt-newline">where<br> K: Hash + Borrow<Q> + From<&'b Q>,<br> S: BuildHasher,</span></h4></section></summary><div class="docblock"><p>Ensures a value is in the entry by inserting, if empty, the result of the default function. |
| This method allows for generating key-derived values for insertion by providing the default |
| function a reference to the key that was moved during the <code>.entry_ref(key)</code> method call.</p> |
| <p>The reference to the moved key is provided so that cloning or copying the key is |
| unnecessary, unlike with <code>.or_insert_with(|| ... )</code>.</p> |
| <h5 id="examples-6"><a href="#examples-6">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::HashMap; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, usize> = HashMap::new(); |
| |
| <span class="comment">// nonexistent key |
| </span>map.entry_ref(<span class="string">"poneyland"</span>).or_insert_with_key(|key| key.chars().count()); |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">9</span>); |
| |
| <span class="comment">// existing key |
| </span><span class="kw-2">*</span>map.entry_ref(<span class="string">"poneyland"</span>).or_insert_with_key(|key| key.chars().count() * <span class="number">10</span>) <span class="kw-2">*</span>= <span class="number">2</span>; |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">18</span>);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.key" class="method has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5735-5743">source</a><h4 class="code-header">pub fn <a href="#method.key" class="fnname">key</a>(&self) -> &Q<span class="where fmt-newline">where<br> K: Borrow<Q>,</span></h4></section></summary><div class="docblock"><p>Returns a reference to this entry’s key.</p> |
| <h5 id="examples-7"><a href="#examples-7">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::HashMap; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, u32> = HashMap::new(); |
| map.entry_ref(<span class="string">"poneyland"</span>).or_insert(<span class="number">3</span>); |
| <span class="comment">// existing key |
| </span><span class="macro">assert_eq!</span>(map.entry_ref(<span class="string">"poneyland"</span>).key(), <span class="string">"poneyland"</span>); |
| <span class="comment">// nonexistent key |
| </span><span class="macro">assert_eq!</span>(map.entry_ref(<span class="string">"horseland"</span>).key(), <span class="string">"horseland"</span>);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.and_modify" class="method has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5766-5777">source</a><h4 class="code-header">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: FnOnce(&mut V),</span></h4></section></summary><div class="docblock"><p>Provides in-place mutable access to an occupied entry before any |
| potential inserts into the map.</p> |
| <h5 id="examples-8"><a href="#examples-8">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::HashMap; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, u32> = HashMap::new(); |
| |
| map.entry_ref(<span class="string">"poneyland"</span>) |
| .and_modify(|e| { <span class="kw-2">*</span>e += <span class="number">1 </span>}) |
| .or_insert(<span class="number">42</span>); |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">42</span>); |
| |
| map.entry_ref(<span class="string">"poneyland"</span>) |
| .and_modify(|e| { <span class="kw-2">*</span>e += <span class="number">1 </span>}) |
| .or_insert(<span class="number">42</span>); |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">43</span>);</code></pre></div> |
| </div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.and_replace_entry_with" class="method has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5834-5843">source</a><h4 class="code-header">pub fn <a href="#method.and_replace_entry_with" class="fnname">and_replace_entry_with</a><F>(self, f: F) -> Self<span class="where fmt-newline">where<br> F: FnOnce(&Q, V) -> Option<V>,<br> K: Borrow<Q>,</span></h4></section></summary><div class="docblock"><p>Provides shared access to the key and owned access to the value of |
| an occupied entry and allows to replace or remove it based on the |
| value of the returned option.</p> |
| <h5 id="examples-9"><a href="#examples-9">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::HashMap; |
| <span class="kw">use </span>hashbrown::hash_map::EntryRef; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, u32> = HashMap::new(); |
| |
| <span class="kw">let </span>entry = map |
| .entry_ref(<span class="string">"poneyland"</span>) |
| .and_replace_entry_with(|_k, _v| <span class="macro">panic!</span>()); |
| |
| <span class="kw">match </span>entry { |
| EntryRef::Vacant(e) => { |
| <span class="macro">assert_eq!</span>(e.key(), <span class="string">"poneyland"</span>); |
| } |
| EntryRef::Occupied(<span class="kw">_</span>) => <span class="macro">panic!</span>(), |
| } |
| |
| map.insert(<span class="string">"poneyland"</span>.to_string(), <span class="number">42</span>); |
| |
| <span class="kw">let </span>entry = map |
| .entry_ref(<span class="string">"poneyland"</span>) |
| .and_replace_entry_with(|k, v| { |
| <span class="macro">assert_eq!</span>(k, <span class="string">"poneyland"</span>); |
| <span class="macro">assert_eq!</span>(v, <span class="number">42</span>); |
| <span class="prelude-val">Some</span>(v + <span class="number">1</span>) |
| }); |
| |
| <span class="kw">match </span>entry { |
| EntryRef::Occupied(e) => { |
| <span class="macro">assert_eq!</span>(e.key(), <span class="string">"poneyland"</span>); |
| <span class="macro">assert_eq!</span>(e.get(), <span class="kw-2">&</span><span class="number">43</span>); |
| } |
| EntryRef::Vacant(<span class="kw">_</span>) => <span class="macro">panic!</span>(), |
| } |
| |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="number">43</span>); |
| |
| <span class="kw">let </span>entry = map |
| .entry_ref(<span class="string">"poneyland"</span>) |
| .and_replace_entry_with(|_k, _v| <span class="prelude-val">None</span>); |
| |
| <span class="kw">match </span>entry { |
| EntryRef::Vacant(e) => <span class="macro">assert_eq!</span>(e.key(), <span class="string">"poneyland"</span>), |
| EntryRef::Occupied(<span class="kw">_</span>) => <span class="macro">panic!</span>(), |
| } |
| |
| <span class="macro">assert!</span>(!map.contains_key(<span class="string">"poneyland"</span>));</code></pre></div> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E-1" class="impl has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5846-5877">source</a><a href="#impl-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E-1" class="anchor"></a><h3 class="code-header">impl<'a, 'b, K, Q: ?Sized, V: Default, S, A: Allocator + Clone> <a class="enum" href="enum.EntryRef.html" title="enum hashbrown::hash_map::EntryRef">EntryRef</a><'a, 'b, K, Q, V, S, A></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.or_default" class="method has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#5867-5876">source</a><h4 class="code-header">pub fn <a href="#method.or_default" class="fnname">or_default</a>(self) -> &'a mut V<span class="where fmt-newline">where<br> K: Hash + From<&'b Q>,<br> S: BuildHasher,</span></h4></section></summary><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> |
| <h5 id="examples-10"><a href="#examples-10">Examples</a></h5> |
| <div class="example-wrap"><pre class="rust rust-example-rendered"><code><span class="kw">use </span>hashbrown::HashMap; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>map: HashMap<String, <span class="prelude-ty">Option</span><u32>> = HashMap::new(); |
| |
| <span class="comment">// nonexistent key |
| </span>map.entry_ref(<span class="string">"poneyland"</span>).or_default(); |
| <span class="macro">assert_eq!</span>(map[<span class="string">"poneyland"</span>], <span class="prelude-val">None</span>); |
| |
| map.insert(<span class="string">"horseland"</span>.to_string(), <span class="prelude-val">Some</span>(<span class="number">3</span>)); |
| |
| <span class="comment">// existing key |
| </span><span class="macro">assert_eq!</span>(map.entry_ref(<span class="string">"horseland"</span>).or_default(), <span class="kw-2">&mut </span><span class="prelude-val">Some</span>(<span class="number">3</span>));</code></pre></div> |
| </div></details></div></details></div><h2 id="trait-implementations" class="small-section-header">Trait Implementations<a href="#trait-implementations" class="anchor"></a></h2><div id="trait-implementations-list"><details class="rustdoc-toggle implementors-toggle" open><summary><section id="impl-Debug-for-EntryRef%3C%27_%2C%20%27_%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#4356-4365">source</a><a href="#impl-Debug-for-EntryRef%3C%27_%2C%20%27_%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<K: Borrow<Q>, Q: ?Sized + Debug, V: Debug, S, A: Allocator + Clone> Debug for <a class="enum" href="enum.EntryRef.html" title="enum hashbrown::hash_map::EntryRef">EntryRef</a><'_, '_, K, Q, V, S, A></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.fmt" class="method trait-impl has-srclink"><a class="srclink rightside" href="../../src/hashbrown/map.rs.html#4359-4364">source</a><a href="#method.fmt" class="anchor"></a><h4 class="code-header">fn <a class="fnname">fmt</a>(&self, f: &mut Formatter<'_>) -> Result</h4></section></summary><div class='docblock'>Formats the value using the given formatter. <a>Read more</a></div></details></div></details></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"><section id="impl-RefUnwindSafe-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-RefUnwindSafe-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<'a, 'b, K, Q: ?Sized, V, S, A> RefUnwindSafe for <a class="enum" href="enum.EntryRef.html" title="enum hashbrown::hash_map::EntryRef">EntryRef</a><'a, 'b, K, Q, V, S, A><span class="where fmt-newline">where<br> A: RefUnwindSafe,<br> K: RefUnwindSafe,<br> Q: RefUnwindSafe,<br> S: RefUnwindSafe,<br> V: RefUnwindSafe,</span></h3></section><section id="impl-Send-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-Send-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<'a, 'b, K, Q: ?Sized, V, S, A> Send for <a class="enum" href="enum.EntryRef.html" title="enum hashbrown::hash_map::EntryRef">EntryRef</a><'a, 'b, K, Q, V, S, A><span class="where fmt-newline">where<br> A: Send,<br> K: Send,<br> Q: Sync,<br> S: Send,<br> V: Send,</span></h3></section><section id="impl-Sync-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-Sync-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<'a, 'b, K, Q: ?Sized, V, S, A> Sync for <a class="enum" href="enum.EntryRef.html" title="enum hashbrown::hash_map::EntryRef">EntryRef</a><'a, 'b, K, Q, V, S, A><span class="where fmt-newline">where<br> A: Sync,<br> K: Sync,<br> Q: Sync,<br> S: Sync,<br> V: Sync,</span></h3></section><section id="impl-Unpin-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-Unpin-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<'a, 'b, K, Q: ?Sized, V, S, A> Unpin for <a class="enum" href="enum.EntryRef.html" title="enum hashbrown::hash_map::EntryRef">EntryRef</a><'a, 'b, K, Q, V, S, A><span class="where fmt-newline">where<br> K: Unpin,</span></h3></section><section id="impl-UnwindSafe-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-UnwindSafe-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<'a, 'b, K, Q, V, S, A = Global> !UnwindSafe for <a class="enum" href="enum.EntryRef.html" title="enum hashbrown::hash_map::EntryRef">EntryRef</a><'a, 'b, K, Q, V, S, A></h3></section></div><h2 id="blanket-implementations" class="small-section-header">Blanket Implementations<a href="#blanket-implementations" class="anchor"></a></h2><div id="blanket-implementations-list"><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-Any-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-Any-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<T> Any for T<span class="where fmt-newline">where<br> T: 'static + ?Sized,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.type_id" class="method trait-impl has-srclink"><a href="#method.type_id" class="anchor"></a><h4 class="code-header">fn <a class="fnname">type_id</a>(&self) -> TypeId</h4></section></summary><div class='docblock'>Gets the <code>TypeId</code> of <code>self</code>. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-Borrow%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-Borrow%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<T> Borrow<T> for T<span class="where fmt-newline">where<br> T: ?Sized,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.borrow" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/91522" title="Tracking issue for const_borrow">unstable</a></span><a href="#method.borrow" class="anchor"></a><h4 class="code-header">fn <a class="fnname">borrow</a>(&self) -> &T</h4></section></summary><div class='docblock'>Immutably borrows from an owned value. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-BorrowMut%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-BorrowMut%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<T> BorrowMut<T> for T<span class="where fmt-newline">where<br> T: ?Sized,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.borrow_mut" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/91522" title="Tracking issue for const_borrow">unstable</a></span><a href="#method.borrow_mut" class="anchor"></a><h4 class="code-header">fn <a class="fnname">borrow_mut</a>(&mut self) -> &mut T</h4></section></summary><div class='docblock'>Mutably borrows from an owned value. <a>Read more</a></div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-From%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-From%3CT%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<T> From<T> for T</h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.from" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/88674" title="Tracking issue for const_convert">unstable</a></span><a href="#method.from" class="anchor"></a><h4 class="code-header">fn <a class="fnname">from</a>(t: T) -> T</h4></section></summary><div class="docblock"><p>Returns the argument unchanged.</p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-Into%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-Into%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<T, U> Into<U> for T<span class="where fmt-newline">where<br> U: From<T>,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle method-toggle" open><summary><section id="method.into" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/88674" title="Tracking issue for const_convert">unstable</a></span><a href="#method.into" class="anchor"></a><h4 class="code-header">fn <a class="fnname">into</a>(self) -> U</h4></section></summary><div class="docblock"><p>Calls <code>U::from(self)</code>.</p> |
| <p>That is, this conversion is whatever the implementation of |
| <code>[From]<T> for U</code> chooses to do.</p> |
| </div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-TryFrom%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-TryFrom%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<T, U> TryFrom<U> for T<span class="where fmt-newline">where<br> U: Into<T>,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle" open><summary><section id="associatedtype.Error-1" class="associatedtype trait-impl has-srclink"><a href="#associatedtype.Error-1" class="anchor"></a><h4 class="code-header">type <a class="associatedtype">Error</a> = Infallible</h4></section></summary><div class='docblock'>The type returned in the event of a conversion error.</div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.try_from" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/88674" title="Tracking issue for const_convert">unstable</a></span><a href="#method.try_from" class="anchor"></a><h4 class="code-header">fn <a class="fnname">try_from</a>(value: U) -> Result<T, <T as TryFrom<U>>::Error></h4></section></summary><div class='docblock'>Performs the conversion.</div></details></div></details><details class="rustdoc-toggle implementors-toggle"><summary><section id="impl-TryInto%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="impl has-srclink"><a href="#impl-TryInto%3CU%3E-for-EntryRef%3C%27a%2C%20%27b%2C%20K%2C%20Q%2C%20V%2C%20S%2C%20A%3E" class="anchor"></a><h3 class="code-header">impl<T, U> TryInto<U> for T<span class="where fmt-newline">where<br> U: TryFrom<T>,</span></h3></section></summary><div class="impl-items"><details class="rustdoc-toggle" open><summary><section id="associatedtype.Error" class="associatedtype trait-impl has-srclink"><a href="#associatedtype.Error" class="anchor"></a><h4 class="code-header">type <a class="associatedtype">Error</a> = <U as TryFrom<T>>::Error</h4></section></summary><div class='docblock'>The type returned in the event of a conversion error.</div></details><details class="rustdoc-toggle method-toggle" open><summary><section id="method.try_into" class="method trait-impl has-srclink"><span class="since rightside" title="const unstable">const: <a href="https://github.com/rust-lang/rust/issues/88674" title="Tracking issue for const_convert">unstable</a></span><a href="#method.try_into" class="anchor"></a><h4 class="code-header">fn <a class="fnname">try_into</a>(self) -> Result<U, <U as TryFrom<T>>::Error></h4></section></summary><div class='docblock'>Performs the conversion.</div></details></div></details></div></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="hashbrown" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
