131 lines
8.4 KiB
HTML
131 lines
8.4 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>std::uses_allocator<std::tuple></title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_utility_tuple_uses_allocator skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::</span>uses_allocator<small><std::tuple></small></h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-utility.html">utility</a>‎ | <a href="cpp-utility-tuple.html">tuple</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dsc-header">
|
|
<td>
|
|
<div>定义于头文件 <code><a href="cpp-header-tuple.html"><tuple></a></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx11">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span>... <span class="me1">Types</span>, <span class="kw1">class</span> Alloc <span class="sy1">></span><br />
|
|
<span class="kw1">struct</span> uses_allocator<span class="sy1"><</span> <a href="cpp-utility-tuple.html"><span class="kw1098">std::<span class="me2">tuple</span></span></a><span class="sy1"><</span>Types...<span class="sy1">></span>, Alloc <span class="sy1">></span> <span class="sy4">:</span> <a href="cpp-types-integral_constant.html"><span class="kw649">std::<span class="me2">true_type</span></span></a> <span class="br0">{</span> <span class="br0">}</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx11">(C++11 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>此 <span class="t-lc"><a href="cpp-memory-uses_allocator.html">std::uses_allocator</a></span> 的特化告诉其他库组件 tuples 支持<i>使用分配器构造</i>，即使它们无嵌套的 <code>allocator_type</code>.</p>
|
|
<div class="t-inherited">
|
|
<h2><span class="mw-headline" id=".E7.BB.A7.E6.89.BF.E8.87.AA_std::integral_constant">继承自 <a href="cpp-types-integral_constant.html"><span style="font-size:0.7em; line-height:130%">std::</span>integral_constant</a></span></h2>
|
|
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.B8.B8.E9.87.8F">成员常量</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><span class="t-lines"><span>value</span></span></div>
|
|
<div><span class="t-lines"><span><span class="t-cmark">[静态]</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span><br />
|
|
<span class="t-mark">(公开静态成员常量)</span></td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><span class="t-lines"><span>operator bool</span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>转换对象为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span></span></span> ，返回 <code>value</code><br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><span class="t-lines"><span>operator()</span></span></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx14">(C++14)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>返回 <code>value</code><br />
|
|
<span class="t-mark">(公开成员函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E7.B1.BB.E5.9E.8B">成员类型</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc-hitem">
|
|
<td>类型</td>
|
|
<td>定义</td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>value_type</code></td>
|
|
<td><code>bool</code></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>type</code></td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-types-integral_constant.html"><span class="kw647">std::<span class="me2">integral_constant</span></span></a><span class="sy1"><</span><span class="kw4">bool</span>, value<span class="sy1">></span></span></span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="co1">// myalloc 是带接收 int 的单参数构造函数的有状态分配器（Allocator）。</span>
|
|
<span class="co1">// 它无默认构造函数</span>
|
|
|
|
<span class="kw1">typedef</span> <a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1"><</span><span class="kw4">int</span>, myalloc<span class="sy1"><</span><span class="kw4">int</span><span class="sy1">>></span> innervector_t<span class="sy4">;</span>
|
|
<span class="kw1">typedef</span> <a href="cpp-utility-tuple.html"><span class="kw1098">std::<span class="me2">tuple</span></span></a><span class="sy1"><</span><span class="kw4">int</span>, innervector_t<span class="sy1">></span> elem_t<span class="sy4">;</span>
|
|
<span class="kw1">typedef</span> <a href="cpp-memory-scoped_allocator_adaptor.html"><span class="kw706">std::<span class="me2">scoped_allocator_adaptor</span></span></a><span class="sy1"><</span> myalloc<span class="sy1"><</span>elem_t<span class="sy1">></span>, myalloc<span class="sy1"><</span><span class="kw4">int</span><span class="sy1">>></span> Alloc<span class="sy4">;</span>
|
|
Alloc a<span class="br0">(</span><span class="nu0">1</span>,<span class="nu0">2</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="cpp-container-vector.html"><span class="kw1269">std::<span class="me2">vector</span></span></a><span class="sy1"><</span>elem_t, Alloc<span class="sy1">></span> v<span class="br0">(</span>a<span class="br0">)</span><span class="sy4">;</span>
|
|
v.<span class="me1">resize</span><span class="br0">(</span><span class="nu0">1</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 对 v 的元素用分配器 #1</span>
|
|
std<span class="sy4">::</span><span class="me2">get</span><span class="sy1"><</span><span class="nu0">1</span><span class="sy1">></span><span class="br0">(</span>v<span class="br0">[</span><span class="nu0">0</span><span class="br0">]</span><span class="br0">)</span>.<span class="me1">resize</span><span class="br0">(</span><span class="nu0">10</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 对 innervector_t 用分配器 #2</span></pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-memory-uses_allocator.html"><span class="t-lines"><span>uses_allocator</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx11">(C++11)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>检查指定的类型是否支持使用分配器的构造<br />
|
|
<span class="t-mark">(类模板)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|