294 lines
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294 lines
34 KiB
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<title>std::ranges::unique_copy, std::ranges::unique_copy_result</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::ranges::</span>unique_copy, <span style="font-size:0.7em; line-height:130%">std::ranges::</span>unique_copy_result</h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-algorithm.html">algorithm</a>‎ | <a href="cpp-algorithm-ranges.html">ranges</a></span></div>
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<div>定义于头文件 <code><a href="cpp-header-algorithm.html"><algorithm></a></code></div>
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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> std<span class="sy4">::</span><span class="me2">input_iterator</span> I, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I<span class="sy1">></span> S, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O,<br /></span>
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<p> <span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,<br />
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std<span class="sy4">::</span><span class="me2">indirect_equivalence_relation</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1"><</span>I, Proj<span class="sy1">>></span> C <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">equal_to</span> <span class="sy1">></span><br />
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requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1"><</span>I, O<span class="sy1">></span> <span class="sy3">&&</span> <span class="br0">(</span>std<span class="sy4">::</span><span class="me2">forward_iterator</span><span class="sy1"><</span>I<span class="sy1">></span> <span class="sy3">||</span><br />
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<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">input_iterator</span><span class="sy1"><</span>O<span class="sy1">></span> <span class="sy3">&&</span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">iter_value_t</span><span class="sy1"><</span>I<span class="sy1">></span>,<br />
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std<span class="sy4">::</span><span class="me2">iter_value_t</span><span class="sy1"><</span>O<span class="sy1">>></span><span class="br0">)</span> <span class="sy3">||</span> std<span class="sy4">::</span><span class="me2">indirectly_copyable_storable</span><span class="sy1"><</span>I, O<span class="sy1">></span><span class="br0">)</span><br />
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<span class="kw4">constexpr</span> unique_copy_result<span class="sy1"><</span>I, O<span class="sy1">></span><br /></p>
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unique_copy<span class="br0">(</span> I first, S last, O result, C comp <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(1)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> ranges<span class="sy4">::</span><span class="me2">input_range</span> R, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O, <span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,<br /></span>
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<p> std<span class="sy4">::</span><span class="me2">indirect_equivalence_relation</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>,<br />
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Proj<span class="sy1">>></span> C <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">equal_to</span> <span class="sy1">></span><br />
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requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>, O<span class="sy1">></span> <span class="sy3">&&</span><br />
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<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">forward_iterator</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">>></span> <span class="sy3">||</span><br />
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<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">input_iterator</span><span class="sy1"><</span>O<span class="sy1">></span> <span class="sy3">&&</span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">range_value_t</span><span class="sy1"><</span>R<span class="sy1">></span>,<br />
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std<span class="sy4">::</span><span class="me2">iter_value_t</span><span class="sy1"><</span>O<span class="sy1">>></span><span class="br0">)</span> <span class="sy3">||</span><br />
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std<span class="sy4">::</span><span class="me2">indirectly_copyable_storable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>, O<span class="sy1">></span><span class="br0">)</span><br />
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<span class="kw4">constexpr</span> unique_copy_result<span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>, O<span class="sy1">></span><br /></p>
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unique_copy<span class="br0">(</span> R<span class="sy3">&&</span> r, O result, C comp <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span><span class="sy4">;</span></div>
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<td>(2)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<div>辅助类型</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> I, <span class="kw1">class</span> O<span class="sy1">></span><br />
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<span class="kw1">using</span> unique_copy_result <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">in_out_result</span><span class="sy1"><</span>I, O<span class="sy1">></span><span class="sy4">;</span></span></div>
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<td>(3)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<div class="t-li1"><span class="t-li">1)</span> 从源范围 <code>[first, last)</code> 复制元素到始于 <code>result</code> 的目标范围,使得无连续的元素比较相等。只复制每群相等元素中的第一个。</div>
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<div class="t-li1"><span class="t-li"></span> 范围 <code>[first, last)</code> 与 <code>[result, result + N)</code> 必须不重叠。 <span class="t-c"><span class="mw-geshi cpp source-cpp">N <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">distance</span><span class="br0">(</span>first, last<span class="br0">)</span></span></span>.</div>
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<div class="t-li1"><span class="t-li"></span> 认为二个连续元素 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span><span class="br0">(</span>i <span class="sy2">-</span> <span class="nu0">1</span><span class="br0">)</span></span></span> 与 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>i</span></span> 比较相等,若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>comp, <a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj, <span class="sy2">*</span><span class="br0">(</span>i <span class="sy2">-</span> <span class="nu0">1</span><span class="br0">)</span><span class="br0">)</span>, <a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj, <span class="sy2">*</span>i<span class="br0">)</span><span class="br0">)</span> <span class="sy1">==</span> <span class="kw2">true</span></span></span> ,其中 <code>i</code> 为范围 <code>[first + 1, last)</code> 中的迭代器。</div>
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<div class="t-li1"><span class="t-li">2)</span> 同 <span class="t-v">(1)</span> ,但以 <code>r</code> 为源范围,如同以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r<span class="br0">)</span></span></span> 为 <code>first</code> 并以 <span class="t-c"><span class="mw-geshi cpp source-cpp">ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r<span class="br0">)</span></span></span> 为 <code>last</code> 。</div>
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<p>此页面上描述的仿函数实体是 <i>niebloid</i> ,即:</p>
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<ul>
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<li>调用它们中的任何一者时不可指定显式模板实参。</li>
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<li>它们无一对<a href="cpp-language-adl.html">实参依赖查找</a>可见。</li>
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<li>在<a href="cpp-language-unqualified_lookup.html">通常无限定查找</a>寻找函数调用运算符左侧的名称找到它们之一时,它禁止<a href="cpp-language-adl.html">实参依赖查找</a>。</li>
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</ul>
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<p>实际上,它们能以函数对象,或以某些特殊编译器扩展实现。</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>first, last</td>
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<td>-</td>
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<td>源元素范围</td>
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</tr>
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<tr class="t-par">
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<td>r</td>
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<td>-</td>
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<td>源元素范围</td>
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</tr>
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<tr class="t-par">
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<td>result</td>
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<td>-</td>
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<td>目标元素范围</td>
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</tr>
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<tr class="t-par">
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<td>comp</td>
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<td>-</td>
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<td>比较投影后元素的谓词</td>
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</tr>
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<td>proj</td>
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<td>-</td>
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<td>应用到谓词的投影</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="br0">{</span>last, result <span class="sy2">+</span> N<span class="br0">}</span></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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<p>准确应用 <span class="t-c"><span class="mw-geshi cpp source-cpp">N <span class="sy2">-</span> <span class="nu0">1</span></span></span> 次对应的谓词 <code>comp</code> 并应用不多于其次数二倍的投影 <code>proj</code> 。</p>
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<h3><span class="mw-headline" id=".E5.8F.AF.E8.83.BD.E7.9A.84.E5.AE.9E.E7.8E.B0">可能的实现</span></h3>
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<p>参阅 <a rel="nofollow" class="external text" href="https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-v3/include/bits/ranges_algo.h#L1198-L1276">libstdc++</a> 与 <a rel="nofollow" class="external text" href="https://github.com/microsoft/STL/blob/472161105d596192194d4715ccad307c6c163b4a/stl/inc/algorithm#L4022-L4113">MSVC STL</a> (及第三方库: <a rel="nofollow" class="external text" href="https://github.com/CaseyCarter/cmcstl2/blob/master/include/stl2/detail/algorithm/unique_copy.hpp">cmcstl2</a>、 <a rel="nofollow" class="external text" href="https://github.com/tcbrindle/NanoRange/blob/master/include/nanorange/algorithm/unique_copy.hpp">NanoRange</a> 和 <a rel="nofollow" class="external text" href="https://github.com/ericniebler/range-v3/blob/master/include/range/v3/algorithm/unique_copy.hpp">range-v3</a> )中的实现。</p>
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<table class="eq-fun-cpp-table">
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="kw1">struct</span> unique_copy_fn <span class="br0">{</span>
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<span class="kw1">template</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">input_iterator</span> I, std<span class="sy4">::</span><span class="me2">sentinel_for</span><span class="sy1"><</span>I<span class="sy1">></span> S, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O,
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<span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,
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std<span class="sy4">::</span><span class="me2">indirect_equivalence_relation</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1"><</span>I, Proj<span class="sy1">>></span> C <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">equal_to</span><span class="sy1">></span>
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requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1"><</span>I, O<span class="sy1">></span> <span class="sy3">&&</span> <span class="br0">(</span>std<span class="sy4">::</span><span class="me2">forward_iterator</span><span class="sy1"><</span>I<span class="sy1">></span> or
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<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">input_iterator</span><span class="sy1"><</span>O<span class="sy1">></span> <span class="sy3">&&</span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">iter_value_t</span><span class="sy1"><</span>I<span class="sy1">></span>,
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std<span class="sy4">::</span><span class="me2">iter_value_t</span><span class="sy1"><</span>O<span class="sy1">>></span><span class="br0">)</span> or std<span class="sy4">::</span><span class="me2">indirectly_copyable_storable</span><span class="sy1"><</span>I, O<span class="sy1">></span><span class="br0">)</span>
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">unique_copy_result</span><span class="sy1"><</span>I, O<span class="sy1">></span>
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operator<span class="br0">(</span><span class="br0">)</span> <span class="br0">(</span> I first, S last, O result, C comp <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span>
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<span class="kw1">if</span> <span class="br0">(</span><span class="sy3">!</span><span class="br0">(</span>first <span class="sy1">==</span> last<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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std<span class="sy4">::</span><span class="me2">iter_value_t</span><span class="sy1"><</span>I<span class="sy1">></span> value <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
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<span class="sy2">*</span>result <span class="sy1">=</span> value<span class="sy4">;</span>
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<span class="sy2">++</span>result<span class="sy4">;</span>
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<span class="kw1">while</span> <span class="br0">(</span><span class="sy3">!</span><span class="br0">(</span><span class="sy2">++</span>first <span class="sy1">==</span> last<span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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<span class="kw4">auto</span><span class="sy3">&&</span> value2 <span class="sy1">=</span> <span class="sy2">*</span>first<span class="sy4">;</span>
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<span class="kw1">if</span> <span class="br0">(</span><span class="sy3">!</span><a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>comp, <a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj, value2<span class="br0">)</span>,
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<a href="cpp-utility-functional-invoke.html"><span class="kw1058">std::<span class="me2">invoke</span></span></a><span class="br0">(</span>proj, value<span class="br0">)</span><span class="br0">)</span><span class="br0">)</span> <span class="br0">{</span>
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value <span class="sy1">=</span> <a href="cpp-utility-forward.html"><span class="kw1117">std::<span class="me2">forward</span></span></a><span class="sy1"><</span>decltype<span class="br0">(</span>value2<span class="br0">)</span><span class="sy1">></span><span class="br0">(</span>value2<span class="br0">)</span><span class="sy4">;</span>
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<span class="sy2">*</span>result <span class="sy1">=</span> value<span class="sy4">;</span>
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<span class="sy2">++</span>result<span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="br0">}</span>
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<span class="br0">}</span>
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<span class="kw1">return</span> <span class="br0">{</span>std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>first<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>result<span class="br0">)</span><span class="br0">}</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw1">template</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">input_range</span> R, std<span class="sy4">::</span><span class="me2">weakly_incrementable</span> O, <span class="kw1">class</span> Proj <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">identity</span>,
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std<span class="sy4">::</span><span class="me2">indirect_equivalence_relation</span><span class="sy1"><</span>std<span class="sy4">::</span><span class="me2">projected</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>,
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Proj<span class="sy1">>></span> C <span class="sy1">=</span> ranges<span class="sy4">::</span><span class="me2">equal_to</span><span class="sy1">></span>
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requires std<span class="sy4">::</span><span class="me2">indirectly_copyable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>, O<span class="sy1">></span> <span class="sy3">&&</span>
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<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">forward_iterator</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">>></span> or
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<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">input_iterator</span><span class="sy1"><</span>O<span class="sy1">></span> <span class="sy3">&&</span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">range_value_t</span><span class="sy1"><</span>R<span class="sy1">></span>,
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std<span class="sy4">::</span><span class="me2">iter_value_t</span><span class="sy1"><</span>O<span class="sy1">>></span><span class="br0">)</span> <span class="sy3">||</span>
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std<span class="sy4">::</span><span class="me2">indirectly_copyable_storable</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>, O<span class="sy1">></span><span class="br0">)</span>
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<span class="kw4">constexpr</span> ranges<span class="sy4">::</span><span class="me2">unique_copy_result</span><span class="sy1"><</span>ranges<span class="sy4">::</span><span class="me2">borrowed_iterator_t</span><span class="sy1"><</span>R<span class="sy1">></span>, O<span class="sy1">></span>
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operator<span class="br0">(</span><span class="br0">)</span> <span class="br0">(</span> R<span class="sy3">&&</span> r, O result, C comp <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span>, Proj proj <span class="sy1">=</span> <span class="br0">{</span><span class="br0">}</span> <span class="br0">)</span> <span class="kw4">const</span> <span class="br0">{</span>
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<span class="kw1">return</span> <span class="br0">(</span><span class="sy2">*</span>this<span class="br0">)</span><span class="br0">(</span>ranges<span class="sy4">::</span><span class="me2">begin</span><span class="br0">(</span>r<span class="br0">)</span>, ranges<span class="sy4">::</span><span class="me2">end</span><span class="br0">(</span>r<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>result<span class="br0">)</span>,
|
|
std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>comp<span class="br0">)</span>, std<span class="sy4">::</span><span class="me2">move</span><span class="br0">(</span>proj<span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span>
|
|
<span class="br0">}</span><span class="sy4">;</span>
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|
<span class="kw1">inline</span> <span class="kw4">constexpr</span> unique_copy_fn unique_copy<span class="br0">{</span><span class="br0">}</span><span class="sy4">;</span></pre></div>
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</div>
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</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <algorithm></span>
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<span class="co2">#include <cmath></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <iterator></span>
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|
<span class="co2">#include <list></span>
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|
<span class="co2">#include <string></span>
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|
<span class="co2">#include <type_traits></span>
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<span class="kw4">void</span> print<span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> rem, <span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> v<span class="br0">)</span> <span class="br0">{</span>
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<span class="kw1">using</span> V <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">remove_cvref_t</span><span class="sy1"><</span>decltype<span class="br0">(</span>v<span class="br0">)</span><span class="sy1">></span><span class="sy4">;</span>
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<span class="kw4">constexpr</span> <span class="kw4">bool</span> sep <span class="br0">{</span><a href="cpp-types-is_same.html"><span class="kw589">std::<span class="me2">is_same_v</span></span></a><span class="sy1"><</span><span class="kw1">typename</span> V<span class="sy4">::</span><span class="me2">value_type</span>, <span class="kw4">int</span><span class="sy1">></span><span class="br0">}</span><span class="sy4">;</span>
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|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> rem <span class="sy1"><<</span> <a href="cpp-io-manip-showpos.html"><span class="kw1770">std::<span class="me2">showpos</span></span></a><span class="sy4">;</span>
|
|
<span class="kw1">for</span> <span class="br0">(</span><span class="kw4">const</span> <span class="kw4">auto</span><span class="sy3">&</span> e <span class="sy4">:</span> v<span class="br0">)</span> <a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> e <span class="sy1"><<</span> <span class="br0">(</span>sep <span class="sy4">?</span> <span class="st0">" "</span> <span class="sy4">:</span> <span class="st0">""</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
|
<span class="br0">}</span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
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<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> s1 <span class="br0">{</span><span class="st0">"The string with many spaces!"</span><span class="br0">}</span><span class="sy4">;</span>
|
|
print<span class="br0">(</span><span class="st0">"s1: "</span>, s1<span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
<a href="cpp-string-basic_string.html"><span class="kw1230">std::<span class="me2">string</span></span></a> s2<span class="sy4">;</span>
|
|
std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">unique_copy</span><span class="br0">(</span>
|
|
s1.<span class="me1">begin</span><span class="br0">(</span><span class="br0">)</span>, s1.<span class="me1">end</span><span class="br0">(</span><span class="br0">)</span>, <a href="cpp-iterator-back_inserter.html"><span class="kw665">std::<span class="me2">back_inserter</span></span></a><span class="br0">(</span>s2<span class="br0">)</span>,
|
|
<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">char</span> c1, <span class="kw4">char</span> c2<span class="br0">)</span><span class="br0">{</span> <span class="kw1">return</span> c1 <span class="sy1">==</span> <span class="st0">' '</span> <span class="sy3">&&</span> c2 <span class="sy1">==</span> <span class="st0">' '</span><span class="sy4">;</span> <span class="br0">}</span>
|
|
<span class="br0">)</span><span class="sy4">;</span>
|
|
print<span class="br0">(</span><span class="st0">"s2: "</span>, s2<span class="br0">)</span><span class="sy4">;</span>
|
|
|
|
|
|
<span class="kw4">const</span> <span class="kw4">auto</span> v1 <span class="sy1">=</span> <span class="br0">{</span> <span class="sy2">-</span><span class="nu0">1</span>, <span class="sy2">+</span><span class="nu0">1</span>, <span class="sy2">+</span><span class="nu0">2</span>, <span class="sy2">-</span><span class="nu0">2</span>, <span class="sy2">-</span><span class="nu0">3</span>, <span class="sy2">+</span><span class="nu0">3</span>, <span class="sy2">-</span><span class="nu0">3</span>, <span class="br0">}</span><span class="sy4">;</span>
|
|
print<span class="br0">(</span><span class="st0">"v1: "</span>, v1<span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="cpp-container-list.html"><span class="kw1275">std::<span class="me2">list</span></span></a><span class="sy1"><</span><span class="kw4">int</span><span class="sy1">></span> v2<span class="sy4">;</span>
|
|
std<span class="sy4">::</span><span class="me2">ranges</span><span class="sy4">::</span><span class="me2">unique_copy</span><span class="br0">(</span>
|
|
v1, <a href="cpp-iterator-back_inserter.html"><span class="kw665">std::<span class="me2">back_inserter</span></span></a><span class="br0">(</span>v2<span class="br0">)</span>,
|
|
<span class="br0">{</span><span class="br0">}</span>, <span class="co1">// 默认比较器 std::ranges::equal_to</span>
|
|
<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span><span class="kw4">int</span> x<span class="br0">)</span> <span class="br0">{</span> <span class="kw1">return</span> std<span class="sy4">::</span><span class="me2">abs</span><span class="br0">(</span>x<span class="br0">)</span><span class="sy4">;</span> <span class="br0">}</span> <span class="co1">// 投影</span>
|
|
<span class="br0">)</span><span class="sy4">;</span>
|
|
print<span class="br0">(</span><span class="st0">"v2: "</span>, v2<span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>输出:</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">s1: The string with many spaces!
|
|
s2: The string with many spaces!
|
|
v1: -1 +1 +2 -2 -3 +3 -3
|
|
v2: -1 +2 -3</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-algorithm-ranges-unique.html"><span class="t-lines"><span>ranges::unique</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>移除范围中的连续重复元素<br />
|
|
<span class="t-mark">(niebloid)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-ranges-copy.html"><span class="t-lines"><span>ranges::copy</span><span>ranges::copy_if</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>将某一范围的元素复制到一个新的位置<br />
|
|
<span class="t-mark">(niebloid)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-ranges-adjacent_find.html"><span class="t-lines"><span>ranges::adjacent_find</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx20">(C++20)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>查找首对相邻的相同(或满足给定谓词的)元素<br />
|
|
<span class="t-mark">(niebloid)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-algorithm-unique_copy.html"><span class="t-lines"><span>unique_copy</span></span></a></div>
|
|
</div>
|
|
</td>
|
|
<td>创建某范围的不含连续重复元素的副本<br />
|
|
<span class="t-mark">(函数模板)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
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</div>
|
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</body>
|
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</html>
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