125 lines
15 KiB
HTML
125 lines
15 KiB
HTML
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<title>std::experimental::ranges::swap</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_experimental_ranges_utility_swap skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::experimental::ranges::</span>swap</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-experimental.html">experimental</a>‎ | <a href="cpp-experimental-ranges.html">ranges</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-experimental-ranges-utility.html"><experimental/ranges/utility></a></code></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">namespace</span> <span class="br0">{</span><br /></span>
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<p> <span class="kw4">constexpr</span> <span class="coMULTI">/* unspecified */</span> swap <span class="sy1">=</span> <span class="coMULTI">/* unspecified */</span><span class="sy4">;</span><br /></p>
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<span class="br0">}</span></div>
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<td><span class="t-mark-rev t-since-ranges-ts t-mark-ts">(范围 TS)</span><br />
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<span class="t-mark">(定制点对象)</span></td>
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<div>调用签名</div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> T, <span class="kw1">class</span> U <span class="sy1">></span><br /></span>
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<p> requires <span class="coMULTI">/* see below */</span><br /></p>
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<span class="kw4">void</span> swap<span class="br0">(</span>T<span class="sy3">&&</span> t, U<span class="sy3">&&</span> u<span class="br0">)</span> <span class="kw1">noexcept</span><span class="br0">(</span><span class="coMULTI">/* see below */</span><span class="br0">)</span><span class="sy4">;</span></div>
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<p>交换 <code>t</code> 和 <code>u</code> 所引用的值。</p>
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<p>调用 <code>ranges::swap</code> 等价于：</p>
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<div class="t-li1"><span class="t-li">1)</span> <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>swap<span class="br0">(</span><a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="br0">(</span>t<span class="br0">)</span>, <a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>U<span class="sy1">></span><span class="br0">(</span>u<span class="br0">)</span><span class="br0">)</span></span></span> ，若该表达式合法，其中以下列候选进行<a href="cpp-language-overload_resolution.html">重载决议</a>：
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<ul>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> T<span class="sy1">></span> <span class="kw4">void</span> swap<span class="br0">(</span>T<span class="sy3">&</span>, T<span class="sy3">&</span><span class="br0">)</span> <span class="sy1">=</span> delete<span class="sy4">;</span></span></span></li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span><span class="kw1">class</span> T, <a href="cpp-types-size_t.html"><span class="kw100">std::<span class="me2">size_t</span></span></a> N<span class="sy1">></span> <span class="kw4">void</span> swap<span class="br0">(</span>T<span class="br0">(</span><span class="sy3">&</span><span class="br0">)</span><span class="br0">[</span>N<span class="br0">]</span>, T<span class="br0">(</span><span class="sy3">&</span><span class="br0">)</span><span class="br0">[</span>N<span class="br0">]</span><span class="br0">)</span> <span class="sy1">=</span> delete<span class="sy4">;</span></span></span></li>
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<li><a href="cpp-language-adl.html">参数依赖查找</a>所找到的任何 <code>swap</code> 的声明。</li>
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</ul>
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<div class="t-li1"><span class="t-li"></span> 若重载决议所选择的函数不交换 <code>t</code> 和 <code>u</code> 所引用的值，则程序为为病式；不要求诊断。</div>
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<div class="t-li1"><span class="t-li">2)</span> 否则为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>ranges<span class="sy4">::</span><span class="me2">swap_ranges</span><span class="br0">(</span>t, u<span class="br0">)</span></span></span> ，若 <code>T</code> 和 <code>U</code> 为到相等长度（但元素类型可能不同）的数组类型的左值引用，且 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">swap</span><span class="br0">(</span><span class="sy2">*</span>t, <span class="sy2">*</span>u<span class="br0">)</span></span></span> 为合法表达式；</div>
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<div class="t-li1"><span class="t-li">3)</span> 否则，若 <code>T</code> 与 <code>U</code> 均为 <code>V&</code> ，而 <code>V</code> 是满足 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-experimental-ranges-concepts-MoveConstructible.html"><span class="kw2550">ranges::<span class="me2">MoveConstructible</span></span></a><span class="sy1"><</span>V<span class="sy1">></span></span></span> 和 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-experimental-ranges-concepts-Assignable.html"><span class="kw2538">ranges::<span class="me2">Assignable</span></span></a><span class="sy1"><</span>V<span class="sy3">&</span>, V<span class="sy1">></span></span></span> 要求的某个类型，则如同用 <span class="t-c"><span class="mw-geshi cpp source-cpp">V v<span class="br0">{</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>t<span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span> t <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>u<span class="br0">)</span><span class="sy4">;</span> u <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>v<span class="br0">)</span><span class="sy4">;</span></span></span> 交换其被引用值。若任一概念的语义要求未得到满足，则程序为病式；不要求诊断。</div>
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<div class="t-li1"><span class="t-li">4)</span> 所有其他情况下，对 <code>ranges::swap</code> 的调用为病式。</div>
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<p>若 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">swap</span></span></span> 调用的每个函数（按上述方式指定）都能用于常量表达式中，则亦能如此使用它。</p>
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<h3><span class="mw-headline" id=".E5.AE.9A.E5.88.B6.E7.82.B9.E5.AF.B9.E8.B1.A1">定制点对象</span></h3>
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<p>名称 <code>ranges::swap</code> 代表一个<i>定制点对象</i>，它是<a href="cpp-named_req-LiteralType.html">字面</a> <a href="cpp-experimental-ranges-concepts-Semiregular.html"><code>Semiregular</code></a> 类类型的<a href="cpp-named_req-FunctionObject.html">函数对象</a>（为说明目的以 <code>SwapT</code> 表示）。<code>SwapT</code> 的所有实例均相等。从而能自由地复制 <code>ranges::swap</code> ，且能交替使用其副本。</p>
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<p>给定类型集合 <code>Args...</code> ，若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-declval.html"><span class="kw1120">std::<span class="me2">declval</span></span></a><span class="sy1"><</span>Args<span class="sy1">></span><span class="br0">(</span><span class="br0">)</span>...</span></span> 满足上面给 <code>ranges::swap</code> 的参数要求，则 <code>SwapT</code> 将满足 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-experimental-ranges-concepts-Invocable.html"><span class="kw2556">ranges::<span class="me2">Invocable</span></span></a><span class="sy1"><</span><span class="kw4">const</span> SwapT, Args...<span class="sy1">></span></span></span> 。否则，没有 <code>SwapT</code> 的函数调用运算符参与重载决议。</p>
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<p>在每个定义 <code>ranges::swap</code> 的翻译单元中，它都指代定制点对象的同一实例。（这表示能自由地在类似 inline 函数和函数模板的东西中使用它，而不违反<a href="cpp-language-definition.html#.E5.8D.95.E4.B8.80.E5.AE.9A.E4.B9.89.E8.A7.84.E5.88.99.EF.BC.88ODR.EF.BC.89">单一定义规则</a>。）</p>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<div class="t-li1"><span class="t-li">1)</span>
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<div class="t-noexcept-full"><a href="cpp-language-noexcept_spec.html"><tt>noexcept</tt></a> 说明：
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<div class="t-noexcept-box"><span class="t-cc"><span class="mw-geshi cpp source-cpp"><span class="kw1">noexcept</span><span class="br0">(</span><span class="kw1">noexcept</span><span class="br0">(</span><span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>swap<span class="br0">(</span><a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="br0">(</span>t<span class="br0">)</span>, <a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>T<span class="sy1">></span><span class="br0">(</span>u<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span><span class="br0">)</span></span></span></div>
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</div>
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，其中按上述方式找到 <code>swap</code> 。</div>
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<div class="t-li1"><span class="t-li">2)</span>
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<div class="t-noexcept-full"><a href="cpp-language-noexcept_spec.html"><tt>noexcept</tt></a> 说明：
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<div class="t-noexcept-box"><span class="t-cc"><span class="mw-geshi cpp source-cpp"><span class="kw1">noexcept</span><span class="br0">(</span><span class="kw1">noexcept</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">swap</span><span class="br0">(</span><span class="sy2">*</span>t, <span class="sy2">*</span>u<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span></span></span></div>
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<div class="t-li1"><span class="t-li">3)</span>
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<div class="t-noexcept-full"><a href="cpp-language-noexcept_spec.html"><tt>noexcept</tt></a> 说明：
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<div class="t-noexcept-box"><span class="t-cc"><span class="mw-geshi cpp source-cpp"><span class="kw1">noexcept</span><span class="br0">(</span><a href="cpp-types-is_move_constructible.html"><span class="kw542">std::<span class="me2">is_nothrow_move_constructible</span></span></a><span class="sy1"><</span>V<span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span> <span class="sy3">&&</span><br />
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<a href="cpp-types-is_move_assignable.html"><span class="kw560">std::<span class="me2">is_nothrow_move_assignable</span></span></a><span class="sy1"><</span>V<span class="sy1">></span><span class="sy4">::</span><span class="me2">value</span><span class="br0">)</span></span></span></div>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<td class="mbox-text" style="">本节未完成<br />
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原因：暂无示例</td>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<div class="t-dsc-member-div">
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<div><a href="cpp-algorithm-swap.html"><span class="t-lines"><span>swap</span></span></a></div>
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<td>交换两个对象的值<br />
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<span class="t-mark">(函数模板)</span></td>
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