<!DOCTYPE html><htmllang="en"><head><metacharset="utf-8"><metaname="viewport"content="width=device-width, initial-scale=1.0"><metaname="generator"content="rustdoc"><metaname="description"content="A lazily initialized value that implements `Deref` for `T`."><title>Lazy in regex_automata::util::lazy - Rust</title><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/SourceSerif4-Regular-46f98efaafac5295.ttf.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/FiraSans-Regular-018c141bf0843ffd.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/FiraSans-Medium-8f9a781e4970d388.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/SourceCodePro-Regular-562dcc5011b6de7d.ttf.woff2"><linkrel="preload"as="font"type="font/woff2"crossoriginhref="../../../static.files/SourceCodePro-Semibold-d899c5a5c4aeb14a.ttf.woff2"><linkrel="stylesheet"href="../../../static.files/normalize-76eba96aa4d2e634.css"><linkrel="stylesheet"href="../../../static.files/rustdoc-ac92e1bbe349e143.css"><metaname="rustdoc-vars"data-root-path="../../../"data-static-root-path="../../../static.files/"data-current-crate="regex_automata"data-themes=""data-resource-suffix=""data-rustdoc-version="1.76.0 (07dca489a 2024-02-04)"data-channel="1.76.0"data-search-js="search-2b6ce74ff89ae146.js"data-settings-js="settings-4313503d2e1961c2.js"><scriptsrc="../../../static.files/storage-f2adc0d6ca4d09fb.js"></script><scriptdefersrc="sidebar-items.js"></script><scriptdefersrc="../../../static.files/main-305769736d49e732.js"></script><noscript><linkrel="stylesheet"href="../../../static.files/noscript-feafe1bb7466e4bd.css"></noscript><linkrel="alternate icon"type="image/png"href="../../../static.files/favicon-16x16-8b506e7a72182f1c.png"><linkrel="alternate icon"type="image/png"href="../../../static.files/favicon-32x32-422f7d1d52889060.png"><linkrel="icon"type="image/svg+xml"href="../../../static.files/favicon-2c020d218678b618.svg"></head><bodyclass="rustdoc struct"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><navclass="mobile-topbar"><buttonclass="sidebar-menu-toggle">☰</button></nav><navclass="sidebar"><divclass="sidebar-crate"><h2><ahref="../../../regex_automata/index.html">regex_automata</a><spanclass="version">0.4.6</span></h2></div><h2class="location"><ahref="#">Lazy</a></h2><divclass="sidebar-elems"><section><h3><ahref="#implementations">Methods</a></h3><ulclass="block method"><li><ahref="#method.get">get</a></li><li><ahref="#method.new">new</a></li></ul><h3><ahref="#trait-implementations">Trait Implementations</a></h3><ulclass="block trait-implementation"><li><ahref="#impl-Debug-for-Lazy%3CT,+F%3E">Debug</a></li><li><ahref="#impl-Deref-for-Lazy%3CT,+F%3E">Deref</a></li></ul><h3><ahref="#synthetic-implementations">Auto Trait Implementations</a></h3><ulclass="block synthetic-implementation"><li><ahref="#impl-RefUnwindSafe-for-Lazy%3CT,+F%3E">RefUnwindSafe</a></li><li><ahref="#impl-Send-for-Lazy%3CT,+F%3E">Send</a></li><li><ahref="#impl-Sync-for-Lazy%3CT,+F%3E">Sync</a></li><li><ahref="#impl-Unpin-for-Lazy%3CT,+F%3E">Unpin</a></li><li><ahref="#impl-UnwindSafe-for-Lazy%3CT,+F%3E">UnwindSafe</a></li></ul><h3><ahref="#blanket-implementations">Blanket Implementations</a></h3><ulclass="block blanket-implementation"><li><ahref="#impl-Any-for-T">Any</a></li><li><ahref="#impl-Borrow%3CT%3E-for-T">Borrow<T></a></li><li><ahref="#impl-BorrowMut%3CT%3E-for-T">BorrowMut<T></a></li><li><ahref="#impl-From%3CT%3E-for-T">From<T></a></li><li><ahref="#impl-Into%3CU%3E-for-T">Into<U></a></li><li><ahref="#impl-TryFrom%3CU%3E-for-T">TryFrom<U></a></li><li><ahref="#impl-TryInto%3CU%3E-for-T">TryInto<U></a></li></ul></section><h2><ahref="index.html">In regex_automata::util::lazy</a></h2></div></nav><divclass="sidebar-resizer"></div>
<main><divclass="width-limiter"><navclass="sub"><formclass="search-form"><span></span><divid="sidebar-button"tabindex="-1"><ahref="../../../regex_automata/all.html"title="show sidebar"></a></div><inputclass="search-input"name="search"aria-label="Run search in the documentation"autocomplete="off"spellcheck="false"placeholder="Click or press ‘S’ to search, ‘?’ for more options…"type="search"><divid="help-button"tabindex="-1"><ahref="../../../help.html"title="help">?</a></div><divid="settings-menu"tabindex="-1"><ahref="../../../settings.html"title="settings"><imgwidth="22"height="22"alt="Change settings"src="../../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><sectionid="main-content"class="content"><divclass="main-heading"><h1>Struct <ahref="../../index.html">regex_automata</a>::<wbr><ahref="../index.html">util</a>::<wbr><ahref="index.html">lazy</a>::<wbr><aclass="struct"href="#">Lazy</a><buttonid="copy-path"title="Copy item path to clipboard"><imgsrc="../../../static.files/clipboard-7571035ce49a181d.svg"width="19"height="18"alt="Copy item path"></button></h1><spanclass="out-of-band"><aclass="src"href="../../../src/regex_automata/util/lazy.rs.html#52">source</a> · <buttonid="toggle-all-docs"title="collapse all docs">[<span>−</span>]</button></span></div><preclass="rust item-decl"><code>pub struct Lazy<T, F = <aclass="primitive"href="https://doc.rust-lang.org/1.76.0/std/primitive.fn.html">fn</a>() -> T>(<spanclass="comment">/* private fields */</span>);</code></pre><detailsclass="toggle top-doc"open><summaryclass="hideme"><span>Expand description</span></summary><divclass="docblock"><p>A lazily initialized value that implements <code>Deref</code> for <code>T</code>.</p>
<p>A <code>Lazy</code> takes an initialization function and permits callers from any
thread to access the result of that initialization function in a safe
manner. In effect, this permits one-time initialization of global resources
in a (possibly) multi-threaded program.</p>
<p>This type and its functionality are available even when neither the <code>alloc</code>
nor the <code>std</code> features are enabled. In exchange, a <code>Lazy</code> does <strong>not</strong>
guarantee that the given <code>create</code> function is called at most once. It
might be called multiple times. Moreover, a call to <code>Lazy::get</code> (either
explicitly or implicitly via <code>Lazy</code>’s <code>Deref</code> impl) may block until a <code>T</code>
is available.</p>
<p>This is very similar to <code>lazy_static</code> or <code>once_cell</code>, except it doesn’t
guarantee that the initialization function will be run once and it works
in no-alloc no-std environments. With that said, if you need stronger
guarantees or a more flexible API, then it is recommended to use either
<code>lazy_static</code> or <code>once_cell</code>.</p>
<h2id="warning-may-use-a-spin-lock"><ahref="#warning-may-use-a-spin-lock">Warning: may use a spin lock</a></h2>
<p>When this crate is compiled <em>without</em> the <code>alloc</code> feature, then this type
may used a spin lock internally. This can have subtle effects that may
be undesirable. See <ahref="https://matklad.github.io/2020/01/02/spinlocks-considered-harmful.html">Spinlocks Considered Harmful</a> for a more
</div></details><h2id="implementations"class="section-header">Implementations<ahref="#implementations"class="anchor">§</a></h2><divid="implementations-list"><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Lazy%3CT,+F%3E"class="impl"><aclass="src rightside"href="../../../src/regex_automata/util/lazy.rs.html#54-62">source</a><ahref="#impl-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="code-header">impl<T, F><aclass="struct"href="struct.Lazy.html"title="struct regex_automata::util::lazy::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.new"class="method"><aclass="src rightside"href="../../../src/regex_automata/util/lazy.rs.html#59-61">source</a><h4class="code-header">pub const fn <ahref="#method.new"class="fn">new</a>(create: F) -><aclass="struct"href="struct.Lazy.html"title="struct regex_automata::util::lazy::Lazy">Lazy</a><T, F></h4></section></summary><divclass="docblock"><p>Create a new <code>Lazy</code> value that is initialized via the given function.</p>
<p>The <code>T</code> type is automatically inferred from the return type of the
<code>create</code> function given.</p>
</div></details></div></details><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Lazy%3CT,+F%3E-1"class="impl"><aclass="src rightside"href="../../../src/regex_automata/util/lazy.rs.html#64-81">source</a><ahref="#impl-Lazy%3CT,+F%3E-1"class="anchor">§</a><h3class="code-header">impl<T, F: <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/ops/function/trait.Fn.html"title="trait core::ops::function::Fn">Fn</a>() -> T><aclass="struct"href="struct.Lazy.html"title="struct regex_automata::util::lazy::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.get"class="method"><aclass="src rightside"href="../../../src/regex_automata/util/lazy.rs.html#78-80">source</a><h4class="code-header">pub fn <ahref="#method.get"class="fn">get</a>(this: &<aclass="struct"href="struct.Lazy.html"title="struct regex_automata::util::lazy::Lazy">Lazy</a><T, F>) -><aclass="primitive"href="https://doc.rust-lang.org/1.76.0/std/primitive.reference.html">&T</a></h4></section></summary><divclass="docblock"><p>Return a reference to the lazily initialized value.</p>
<p>This routine may block if another thread is initializing a <code>T</code>.</p>
<p>Note that given a <code>x</code> which has type <code>Lazy</code>, this must be called via
<code>Lazy::get(x)</code> and not <code>x.get()</code>. This routine is defined this way
because <code>Lazy</code> impls <code>Deref</code> with a target of <code>T</code>.</p>
<h5id="panics"><ahref="#panics">Panics</a></h5>
<p>This panics if the <code>create</code> function inside this lazy value panics.
If the panic occurred in another thread, then this routine <em>may</em> also
panic (but is not guaranteed to do so).</p>
</div></details></div></details></div><h2id="trait-implementations"class="section-header">Trait Implementations<ahref="#trait-implementations"class="anchor">§</a></h2><divid="trait-implementations-list"><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Debug-for-Lazy%3CT,+F%3E"class="impl"><aclass="src rightside"href="../../../src/regex_automata/util/lazy.rs.html#91-95">source</a><ahref="#impl-Debug-for-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="code-header">impl<T: <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/fmt/trait.Debug.html"title="trait core::fmt::Debug">Debug</a>, F: <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/ops/function/trait.Fn.html"title="trait core::ops::function::Fn">Fn</a>() -> T><aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/fmt/trait.Debug.html"title="trait core::fmt::Debug">Debug</a> for <aclass="struct"href="struct.Lazy.html"title="struct regex_automata::util::lazy::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.fmt"class="method trait-impl"><aclass="src rightside"href="../../../src/regex_automata/util/lazy.rs.html#92-94">source</a><ahref="#method.fmt"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.76.0/core/fmt/trait.Debug.html#tymethod.fmt"class="fn">fmt</a>(&self, f: &mut <aclass="struct"href="https://doc.rust-lang.org/1.76.0/core/fmt/struct.Formatter.html"title="struct core::fmt::Formatter">Formatter</a><'_>) -><aclass="type"href="https://doc.rust-lang.org/1.76.0/core/fmt/type.Result.html"title="type core::fmt::Result">Result</a></h4></section></summary><divclass='docblock'>Formats the value using the given formatter. <ahref="https://doc.rust-lang.org/1.76.0/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></div></details></div></details><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-Deref-for-Lazy%3CT,+F%3E"class="impl"><aclass="src rightside"href="../../../src/regex_automata/util/lazy.rs.html#83-89">source</a><ahref="#impl-Deref-for-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="code-header">impl<T, F: <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/ops/function/trait.Fn.html"title="trait core::ops::function::Fn">Fn</a>() -> T><aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/ops/deref/trait.Deref.html"title="trait core::ops::deref::Deref">Deref</a> for <aclass="struct"href="struct.Lazy.html"title="struct regex_automata::util::lazy::Lazy">Lazy</a><T, F></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Target"class="associatedtype trait-impl"><ahref="#associatedtype.Target"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.76.0/core/ops/deref/trait.Deref.html#associatedtype.Target"class="associatedtype">Target</a> = T</h4></section></summary><divclass='docblock'>The resulting type after dereferencing.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.deref"class="method trait-impl"><aclass="src rightside"href="../../../src/regex_automata/util/lazy.rs.html#86-88">source</a><ahref="#method.deref"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.76.0/core/ops/deref/trait.Deref.html#tymethod.deref"class="fn">deref</a>(&self) -><aclass="primitive"href="https://doc.rust-lang.org/1.76.0/std/primitive.reference.html">&T</a></h4></section></summary><divclass='docblock'>Dereferences the value.</div></details></div></details></div><h2id="synthetic-implementations"class="section-header">Auto Trait Implementations<ahref="#synthetic-implementations"class="anchor">§</a></h2><divid="synthetic-implementations-list"><sectionid="impl-RefUnwindSafe-for-Lazy%3CT,+F%3E"class="impl"><ahref="#impl-RefUnwindSafe-for-Lazy%3CT,+F%3E"class="anchor">§</a><h3class="cod
<p>That is, this conversion is whatever the implementation of
<code><ahref="https://doc.rust-lang.org/1.76.0/core/convert/trait.From.html"title="trait core::convert::From">From</a><T> for U</code> chooses to do.</p>
</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-TryFrom%3CU%3E-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.76.0/src/core/convert/mod.rs.html#803-805">source</a><ahref="#impl-TryFrom%3CU%3E-for-T"class="anchor">§</a><h3class="code-header">impl<T, U><aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U> for T<divclass="where">where
U: <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.Into.html"title="trait core::convert::Into">Into</a><T>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Error"class="associatedtype trait-impl"><ahref="#associatedtype.Error"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html#associatedtype.Error"class="associatedtype">Error</a> = <aclass="enum"href="https://doc.rust-lang.org/1.76.0/core/convert/enum.Infallible.html"title="enum core::convert::Infallible">Infallible</a></h4></section></summary><divclass='docblock'>The type returned in the event of a conversion error.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.try_from"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.76.0/src/core/convert/mod.rs.html#810">source</a><ahref="#method.try_from"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html#tymethod.try_from"class="fn">try_from</a>(value: U) -><aclass="enum"href="https://doc.rust-lang.org/1.76.0/core/result/enum.Result.html"title="enum core::result::Result">Result</a><T, <T as <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><divclass='docblock'>Performs the conversion.</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-TryInto%3CU%3E-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.76.0/src/core/convert/mod.rs.html#788-790">source</a><ahref="#impl-TryInto%3CU%3E-for-T"class="anchor">§</a><h3class="code-header">impl<T, U><aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryInto.html"title="trait core::convert::TryInto">TryInto</a><U> for T<divclass="where">where
U: <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Error-1"class="associatedtype trait-impl"><ahref="#associatedtype.Error-1"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryInto.html#associatedtype.Error"class="associatedtype">Error</a> = <U as <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a></h4></section></summary><divclass='docblock'>The type returned in the event of a conversion error.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.try_into"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.76.0/src/core/convert/mod.rs.html#795">source</a><ahref="#method.try_into"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryInto.html#tymethod.try_into"class="fn">try_into</a>(self) -><aclass="enum"href="https://doc.rust-lang.org/1.76.0/core/result/enum.Result.html"title="enum core::result::Result">Result</a><U, <U as <aclass="trait"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.76.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><divclass='docblock'>Performs the conversion.</div></details></div></details></div></section></div></main></body></html>
