98 lines
12 KiB
HTML
98 lines
12 KiB
HTML
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<title>std::basic_stacktrace<Allocator>::operator=</title>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_utility_basic_stacktrace_operator skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::basic_stacktrace<Allocator>::</span>operator=</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-utility.html">utility</a>‎ | <a href="cpp-utility-basic_stacktrace.html">basic stacktrace</a></span></div>
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<table class="t-dcl-begin">
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<tr class="t-dcl t-since-cxx23">
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<td>
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<div><span class="mw-geshi cpp source-cpp">basic_stacktrace<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span> <span class="kw4">const</span> basic_stacktrace<span class="sy3">&</span> other <span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx23">(C++23 起)</span></td>
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<tr class="t-dcl t-since-cxx23">
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<div><span class="mw-geshi cpp source-cpp">basic_stacktrace<span class="sy3">&</span> operator<span class="sy1">=</span><span class="br0">(</span> basic_stacktrace<span class="sy3">&&</span> other <span class="br0">)</span><br />
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<span class="kw1">noexcept</span><span class="br0">(</span><span class="coMULTI">/* see below */</span><span class="br0">)</span><span class="sy4">;</span></span></div>
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</td>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx23">(C++23 起)</span></td>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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<p>替换 <code>basic_stacktrace</code> 的内容。</p>
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<div class="t-li1"><span class="t-li">1)</span> 复制赋值运算符。以 <code>other</code> 的副本替换内容。</div>
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<div class="t-li1"><span class="t-li"></span> 若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-allocator_traits.html"><span class="kw701">std::<span class="me2">allocator_traits</span></span></a><span class="sy1"><</span>allocator_type<span class="sy1">></span><span class="sy4">::</span><span class="me2">propagate_on_container_copy_assignment</span><span class="sy4">::</span><span class="me2">value</span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ，则用 <code>other</code> 的分配器的副本替换 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的分配器。若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的分配器在赋值后将与其旧值比较不相等，则用旧分配器解分配内存，然后在复制条目前用新分配器分配内存。否则，在可行时可能复用 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 所拥有的内存。</div>
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<div class="t-li1"><span class="t-li">2)</span> 移动赋值运算符。用移动语义以 <code>other</code> 的内容替换内容（即从 <code>other</code> 移动 <code>other</code> 中的数据到 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 中）。之后 <code>other</code> 在合法但未指定的状态。</div>
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<div class="t-li1"><span class="t-li"></span> 若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-allocator_traits.html"><span class="kw701">std::<span class="me2">allocator_traits</span></span></a><span class="sy1"><</span>allocator_type<span class="sy1">></span><span class="sy4">::</span><span class="me2">propagate_on_container_move_assignment</span><span class="sy4">::</span><span class="me2">value</span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ，则用 <code>other</code> 的分配器的副本替换 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的分配器。若它为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">false</span></span></span> 且 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 与 <code>other</code> 的分配器不比较相等，则 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 不能接管 <code>other</code> 所拥有的内存的所有权且必须单独地移动赋值每个条目，并用其自身的分配器按需分配额外内存。</div>
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<p>任何情况下，原属于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 的栈踪条目要么被销毁，要么被逐元素赋值替换。</p>
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<p>若实现强化异常说明，则在分配失败时 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 可能被设为空。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>other</td>
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<td>-</td>
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<td>用作源的另一 <code>basic_stacktrace</code></td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span></p>
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<h3><span class="mw-headline" id=".E5.A4.8D.E6.9D.82.E5.BA.A6">复杂度</span></h3>
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<div class="t-li1"><span class="t-li">1)</span> 与 <code>*this</code> 和 <code>other</code> 的大小成线性。</div>
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<div class="t-li1"><span class="t-li">2)</span> 与 <code>*this</code> 的大小成线性，除非分配器不比较相等且不传播，该情况下与 <code>*this</code> 和 <code>other</code> 的大小成线性。</div>
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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> 可能抛出实现定义的异常。</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><a href="cpp-memory-allocator_traits.html"><span class="kw701">std::<span class="me2">allocator_traits</span></span></a><span class="sy1"><</span>Allocator<span class="sy1">></span><span class="sy4">::</span><span class="me2">propagate_on_container_move_assignment</span><span class="sy4">::</span><span class="me2">value</span><br />
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<span class="sy3">||</span> <a href="cpp-memory-allocator_traits.html"><span class="kw701">std::<span class="me2">allocator_traits</span></span></a><span class="sy1"><</span>Allocator<span class="sy1">></span><span class="sy4">::</span><span class="me2">is_always_equal</span><span class="sy4">::</span><span class="me2">value</span><span class="br0">)</span></span></span></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E6.B3.A8.E8.A7.A3">注解</span></h3>
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<p>在容器移动赋值（重载 <span class="t-v">(2)</span> ）后，除非不兼容的分配器强制逐元素移动赋值，指向 <code>other</code> 的引用及迭代器（除了尾迭代器）保持合法，但指代现于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 中的元素。当前标准由 <a rel="nofollow" class="external text" href="https://eel.is/c++draft/container.requirements.general#12">[container.requirements.general]/12</a> 中的总括陈述作出此保证，而 <a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue2321">LWG 2321</a> 正在考虑更严格的保证。</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<table class="metadata plainlinks ambox mbox-small-left ambox-notice" style="">
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<td class="mbox-empty-cell"></td>
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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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</table>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<div class="t-dsc-member-div t-dsc-member-nobold-div">
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<div><a href="cpp-utility-basic_stacktrace-basic_stacktrace.html"><span class="t-lines"><span>(构造函数)</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx23">(C++23)</span></span></span></div>
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</div>
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</td>
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<td>创建新的 <code>basic_stacktrace</code><br />
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<span class="t-mark">(公开成员函数)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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