Sophie: rust-doc-1.35.0-1.mga7 armv7hl

rust-doc-1.35.0-1.mga7.armv7hl.rpm

<!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="Source to the Rust file `src/libstd/io/lazy.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>lazy.rs.html -- source</title><link rel="stylesheet" type="text/css" href="../../../normalize1.35.0.css"><link rel="stylesheet" type="text/css" href="../../../rustdoc1.35.0.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../../dark1.35.0.css"><link rel="stylesheet" type="text/css" href="../../../light1.35.0.css" id="themeStyle"><script src="../../../storage1.35.0.js"></script><noscript><link rel="stylesheet" href="../../../noscript1.35.0.css"></noscript><link rel="shortcut icon" href="../../../favicon1.35.0.ico"><style type="text/css">#crate-search{background-image:url("../../../down-arrow1.35.0.svg");}</style></head><body class="rustdoc source"><!--[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><a href='../../../std/index.html'><img src='../../../rust-logo1.35.0.png' alt='logo' width='100'></a></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../../brush1.35.0.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../../theme1.35.0.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"></div><a id="settings-menu" href="../../../settings.html"><img src="../../../wheel1.35.0.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><pre class="line-numbers"><span id="1"> 1</span>
<span id="2"> 2</span>
<span id="3"> 3</span>
<span id="4"> 4</span>
<span id="5"> 5</span>
<span id="6"> 6</span>
<span id="7"> 7</span>
<span id="8"> 8</span>
<span id="9"> 9</span>
<span id="10">10</span>
<span id="11">11</span>
<span id="12">12</span>
<span id="13">13</span>
<span id="14">14</span>
<span id="15">15</span>
<span id="16">16</span>
<span id="17">17</span>
<span id="18">18</span>
<span id="19">19</span>
<span id="20">20</span>
<span id="21">21</span>
<span id="22">22</span>
<span id="23">23</span>
<span id="24">24</span>
<span id="25">25</span>
<span id="26">26</span>
<span id="27">27</span>
<span id="28">28</span>
<span id="29">29</span>
<span id="30">30</span>
<span id="31">31</span>
<span id="32">32</span>
<span id="33">33</span>
<span id="34">34</span>
<span id="35">35</span>
<span id="36">36</span>
<span id="37">37</span>
<span id="38">38</span>
<span id="39">39</span>
<span id="40">40</span>
<span id="41">41</span>
<span id="42">42</span>
<span id="43">43</span>
<span id="44">44</span>
<span id="45">45</span>
<span id="46">46</span>
<span id="47">47</span>
<span id="48">48</span>
<span id="49">49</span>
<span id="50">50</span>
<span id="51">51</span>
<span id="52">52</span>
<span id="53">53</span>
<span id="54">54</span>
<span id="55">55</span>
<span id="56">56</span>
<span id="57">57</span>
<span id="58">58</span>
<span id="59">59</span>
<span id="60">60</span>
<span id="61">61</span>
<span id="62">62</span>
<span id="63">63</span>
<span id="64">64</span>
</pre><div class="example-wrap"><pre class="rust ">
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">cell</span>::<span class="ident">Cell</span>;
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">ptr</span>;
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">sync</span>::<span class="ident">Arc</span>;
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">sys_common</span>;
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">sys_common</span>::<span class="ident">mutex</span>::<span class="ident">Mutex</span>;

<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Lazy</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> {
    <span class="comment">// We never call `lock.init()`, so it is UB to attempt to acquire this mutex reentrantly!</span>
    <span class="ident">lock</span>: <span class="ident">Mutex</span>,
    <span class="ident">ptr</span>: <span class="ident">Cell</span><span class="op">&lt;</span><span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Arc</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;&gt;</span>,
}

<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">const</span> <span class="kw">fn</span> <span class="ident">done</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span>() <span class="op">-&gt;</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Arc</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> { <span class="number">1_usize</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="kw">_</span> }

<span class="kw">unsafe</span> <span class="kw">impl</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> <span class="ident">Sync</span> <span class="kw">for</span> <span class="ident">Lazy</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> {}

<span class="kw">impl</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> <span class="ident">Lazy</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> {
    <span class="kw">pub</span> <span class="kw">const</span> <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-&gt;</span> <span class="ident">Lazy</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> {
        <span class="ident">Lazy</span> {
            <span class="ident">lock</span>: <span class="ident">Mutex</span>::<span class="ident">new</span>(),
            <span class="ident">ptr</span>: <span class="ident">Cell</span>::<span class="ident">new</span>(<span class="ident">ptr</span>::<span class="ident">null_mut</span>()),
        }
    }
}

<span class="kw">impl</span><span class="op">&lt;</span><span class="ident">T</span>: <span class="ident">Send</span> <span class="op">+</span> <span class="ident">Sync</span> <span class="op">+</span> <span class="lifetime">&#39;static</span><span class="op">&gt;</span> <span class="ident">Lazy</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> {
    <span class="doccomment">/// Safety: `init` must not call `get` on the variable that is being</span>
    <span class="doccomment">/// initialized.</span>
    <span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">get</span>(<span class="kw-2">&amp;</span><span class="lifetime">&#39;static</span> <span class="self">self</span>, <span class="ident">init</span>: <span class="kw">fn</span>() <span class="op">-&gt;</span> <span class="ident">Arc</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span>) <span class="op">-&gt;</span> <span class="prelude-ty">Option</span><span class="op">&lt;</span><span class="ident">Arc</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;&gt;</span> {
        <span class="kw">let</span> <span class="ident">_guard</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">lock</span>.<span class="ident">lock</span>();
        <span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">get</span>();
        <span class="kw">if</span> <span class="ident">ptr</span>.<span class="ident">is_null</span>() {
            <span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">init</span>(<span class="ident">init</span>))
        } <span class="kw">else</span> <span class="kw">if</span> <span class="ident">ptr</span> <span class="op">==</span> <span class="ident">done</span>() {
            <span class="prelude-val">None</span>
        } <span class="kw">else</span> {
            <span class="prelude-val">Some</span>((<span class="kw-2">*</span><span class="ident">ptr</span>).<span class="ident">clone</span>())
        }
    }

    <span class="comment">// Must only be called with `lock` held</span>
    <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">init</span>(<span class="kw-2">&amp;</span><span class="lifetime">&#39;static</span> <span class="self">self</span>, <span class="ident">init</span>: <span class="kw">fn</span>() <span class="op">-&gt;</span> <span class="ident">Arc</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span>) <span class="op">-&gt;</span> <span class="ident">Arc</span><span class="op">&lt;</span><span class="ident">T</span><span class="op">&gt;</span> {
        <span class="comment">// If we successfully register an at exit handler, then we cache the</span>
        <span class="comment">// `Arc` allocation in our own internal box (it will get deallocated by</span>
        <span class="comment">// the at exit handler). Otherwise we just return the freshly allocated</span>
        <span class="comment">// `Arc`.</span>
        <span class="kw">let</span> <span class="ident">registered</span> <span class="op">=</span> <span class="ident">sys_common</span>::<span class="ident">at_exit</span>(<span class="kw">move</span> <span class="op">||</span> {
            <span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> {
                <span class="kw">let</span> <span class="ident">_guard</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">lock</span>.<span class="ident">lock</span>();
                <span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">replace</span>(<span class="ident">done</span>())
            };
            <span class="ident">drop</span>(<span class="ident">Box</span>::<span class="ident">from_raw</span>(<span class="ident">ptr</span>))
        });
        <span class="comment">// This could reentrantly call `init` again, which is a problem</span>
        <span class="comment">// because our `lock` allows reentrancy!</span>
        <span class="comment">// That&#39;s why `get` is unsafe and requires the caller to ensure no reentrancy happens.</span>
        <span class="kw">let</span> <span class="ident">ret</span> <span class="op">=</span> <span class="ident">init</span>();
        <span class="kw">if</span> <span class="ident">registered</span>.<span class="ident">is_ok</span>() {
            <span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">set</span>(<span class="ident">Box</span>::<span class="ident">into_raw</span>(<span class="ident">Box</span>::<span class="ident">new</span>(<span class="ident">ret</span>.<span class="ident">clone</span>())));
        }
        <span class="ident">ret</span>
    }
}
</pre></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 = "std";</script><script src="../../../aliases.js"></script><script src="../../../main1.35.0.js"></script><script src="../../../source-script1.35.0.js"></script><script src="../../../source-files.js"></script><script defer src="../../../search-index.js"></script></body></html>