521 lines
54 KiB
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521 lines
54 KiB
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<title>std::ranges::iota_view<W, Bound>::iterator</title>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::ranges::</span><span style="font-size:0.7em; line-height:130%">iota_view<W, Bound>::</span><i>iterator</i></h1>
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-ranges.html">ranges</a>‎ | <a href="cpp-ranges-iota_view.html">iota view</a></span></div>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">struct</span> <span class="coMULTI">/*iterator*/</span><span class="sy4">;</span></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>辅助别名模板</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="sy1">></span><br />
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<span class="kw1">using</span> <span class="coMULTI">/*iota-diff-t*/</span> <span class="sy1">=</span> <span class="coMULTI">/* see below */</span><span class="sy4">;</span> <span class="co1">// 仅用于阐释</span></span></div>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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<div>辅助概念</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="sy1">></span><br /></span>
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<p>concept <span class="coMULTI">/*decrementable*/</span> <span class="sy1">=</span> <span class="co1">// 仅用于阐释</span><br />
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std<span class="sy4">::</span><span class="me2">incrementable</span><span class="sy1"><</span>I<span class="sy1">></span> <span class="sy3">&&</span> requires<span class="br0">(</span>I i<span class="br0">)</span> <span class="br0">{</span><br />
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<span class="br0">{</span> <span class="sy2">--</span>i <span class="br0">}</span> <span class="sy2">-</span><span class="sy1">></span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1"><</span>I<span class="sy3">&</span><span class="sy1">></span><span class="sy4">;</span><br />
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<span class="br0">{</span> i<span class="sy2">--</span> <span class="br0">}</span> <span class="sy2">-</span><span class="sy1">></span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1"><</span>I<span class="sy1">></span><span class="sy4">;</span><br /></p>
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<span class="br0">}</span><span class="sy4">;</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><span class="mw-geshi cpp source-cpp"><span class="kw1">template</span><span class="sy1"><</span> <span class="kw1">class</span> I <span class="sy1">></span><br /></span>
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<p>concept <span class="coMULTI">/*advanceable*/</span> <span class="sy1">=</span> <span class="co1">// 仅用于阐释</span><br />
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<span class="coMULTI">/*decrementable*/</span><span class="sy1"><</span>I<span class="sy1">></span> <span class="sy3">&&</span> std<span class="sy4">::</span><span class="me2">totally_ordered</span><span class="sy1"><</span>I<span class="sy1">></span> <span class="sy3">&&</span><br />
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requires<span class="br0">(</span>I i, <span class="kw4">const</span> I j, <span class="kw4">const</span> <span class="coMULTI">/*iota-diff-t*/</span><span class="sy1"><</span>I<span class="sy1">></span> n<span class="br0">)</span> <span class="br0">{</span><br />
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<span class="br0">{</span> i <span class="sy2">+</span><span class="sy1">=</span> n <span class="br0">}</span> <span class="sy2">-</span><span class="sy1">></span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1"><</span>I<span class="sy3">&</span><span class="sy1">></span><span class="sy4">;</span><br />
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<span class="br0">{</span> i <span class="sy2">-</span><span class="sy1">=</span> n <span class="br0">}</span> <span class="sy2">-</span><span class="sy1">></span> std<span class="sy4">::</span><span class="me2">same_as</span><span class="sy1"><</span>I<span class="sy3">&</span><span class="sy1">></span><span class="sy4">;</span><br />
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I<span class="br0">(</span>j <span class="sy2">+</span> n<span class="br0">)</span><span class="sy4">;</span><br />
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I<span class="br0">(</span>n <span class="sy2">+</span> j<span class="br0">)</span><span class="sy4">;</span><br />
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I<span class="br0">(</span>j <span class="sy2">-</span> n<span class="br0">)</span><span class="sy4">;</span><br />
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<span class="br0">{</span> j <span class="sy2">-</span> j <span class="br0">}</span> <span class="sy2">-</span><span class="sy1">></span> std<span class="sy4">::</span><span class="me2">convertible_to</span><span class="sy1"><</span><span class="coMULTI">/*iota-diff-t*/</span><span class="sy1"><</span>I<span class="sy1">>></span><span class="sy4">;</span><br /></p>
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<span class="br0">}</span><span class="sy4">;</span></div>
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<td>(4)</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> <a href="cpp-ranges-iota_view.html"><tt>iota_view::begin</tt></a> 的返回类型。此类的名称（此处示为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iterator*/</span></span></span> ）是未指明的。</div>
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<div class="t-li1"><span class="t-li">2)</span> 仅用于阐释的别名模板 <code><i>iota-diff-t</i></code> 计算迭代器类型和<a href="cpp-iterator-weakly_incrementable.html#.E6.95.B4.E6.95.B0.E5.BC.8F.E7.B1.BB.E5.9E.8B">整数式类型</a>的差类型。
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<ul>
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<li>若 <code>W</code> 不是整数类型，或若它是整数类型且 <span class="t-c"><span class="mw-geshi cpp source-cpp">sizeof<span class="br0">(</span>std<span class="sy4">::</span><span class="me2">iter_difference_t</span><span class="sy1"><</span>I<span class="sy1">></span><span class="br0">)</span></span></span> 大于 <span class="t-c"><span class="mw-geshi cpp source-cpp">sizeof<span class="br0">(</span>I<span class="br0">)</span></span></span> ，则 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iota-diff-t*/</span><span class="sy1"><</span>I<span class="sy1">></span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp">std<span class="sy4">::</span><span class="me2">iter_difference_t</span><span class="sy1"><</span>I<span class="sy1">></span></span></span> 。</li>
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<li>否则，若 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iota-diff-t*/</span><span class="sy1"><</span>I<span class="sy1">></span></span></span> 宽度大于 <code>I</code> 的有符号整数类型，若这种类型存在。</li>
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<li>否则， <code>I</code> 是最宽的整数类型之一，而 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iota-diff-t*/</span><span class="sy1"><</span>I<span class="sy1">></span></span></span> 是宽度不小于 <code>I</code> 的未指明的<a href="cpp-iterator-weakly_incrementable.html#.E6.95.B4.E6.95.B0.E5.BC.8F.E7.B1.BB.E5.9E.8B">有符号整数式类型</a>。此情况下不指定 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iota-diff-t*/</span><span class="sy1"><</span>I<span class="sy1">></span></span></span> 是否实现 <a href="cpp-iterator-weakly_incrementable.html"><code>weakly_incrementable</code></a> 。</li>
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</ul>
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</div>
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<div class="t-li1"><span class="t-li">3)</span> 仅用于阐释的概念 <code><i>decrementable</i></code> 指定类型为 <a href="cpp-iterator-incrementable.html"><code>incrementable</code></a> ，而且该类型的前与后 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">--</span></span></span> 均拥有通常含义。</div>
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<div class="t-li1"><span class="t-li">4)</span> 仅用于阐释的概念 <code><i>advanceable</i></code> 指定类型为 <code><i>decrementable</i></code> 及 <a href="cpp-concepts-totally_ordered.html"><code>totally_ordered</code></a> ，而且该类型与其差类型间的 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">+</span><span class="sy1">=</span></span></span>、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">-</span><span class="sy1">=</span></span></span>、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">+</span></span></span> 和 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">-</span></span></span> 均拥有通常含义。</div>
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<h3><span class="mw-headline" id=".E8.AF.AD.E4.B9.89.E8.A6.81.E6.B1.82">语义要求</span></h3>
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<div class="t-li1"><span class="t-li">3)</span> 类型 <code>I</code> 实现 <code><i>decrementable</i></code> ，仅若 <code>I</code> 满足 <code><i>decrementable</i></code> 且所有其所蕴含的概念均得到实现，并且给定相等的 <code>I</code> 类型对象 <code>a</code> 与 <code>b</code> ：
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<ul>
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<li>若 <code>a</code> 与 <code>b</code> 在前与后 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">--</span></span></span> 的定义域内（即它们可自减），则以下均为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> ：
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<ul>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span><span class="sy2">--</span>a<span class="br0">)</span> <span class="sy1">==</span> <a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>a<span class="br0">)</span></span></span>、</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>a<span class="sy2">--</span> <span class="sy1">==</span> b<span class="br0">)</span></span></span>、</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span><span class="br0">(</span><span class="br0">(</span><span class="kw4">void</span><span class="br0">)</span>a<span class="sy2">--</span>, a<span class="br0">)</span> <span class="sy1">==</span> <span class="sy2">--</span>b<span class="br0">)</span></span></span>、</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span><span class="sy2">++</span><span class="br0">(</span><span class="sy2">--</span>a<span class="br0">)</span> <span class="sy1">==</span> b<span class="br0">)</span></span></span> 。</li>
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</ul>
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</li>
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<li>若 <code>a</code> 与 <code>b</code> 在前与后 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">++</span></span></span> 的定义域内（即它们可自增），则 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span><span class="sy2">--</span><span class="br0">(</span><span class="sy2">++</span>a<span class="br0">)</span> <span class="sy1">==</span> b<span class="br0">)</span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 。</li>
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</ul>
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</div>
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<div class="t-li1"><span class="t-li">4)</span> 令 <code>D</code> 代表 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iota-diff-t*/</span><span class="sy1"><</span>I<span class="sy1">></span></span></span> 。类型 <code>I</code> 实现 <code><i>advanceable</i></code> 仅若 <code>I</code> 满足 <code><i>advanceable</i></code> 且所有其所蕴含均得到实现，并且给定
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<ul>
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<li><code>I</code> 类型对象 <code>a</code> 与 <code>b</code> 及</li>
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<li><code>D</code> 类型值 <code>n</code> ，</li>
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</ul>
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<p>使得 <code>b</code> 可在 <code>n</code> 次应用 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">++</span>a</span></span> 后从 <code>a</code> 可达，下列所有条件都得到满足：</p>
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<ul>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>a <span class="sy2">+</span><span class="sy1">=</span> n<span class="br0">)</span></span></span> 等于 <code>b</code> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>a <span class="sy2">+</span><span class="sy1">=</span> n<span class="br0">)</span></span></span> 等于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>a<span class="br0">)</span></span></span> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp">I<span class="br0">(</span>a <span class="sy2">+</span> n<span class="br0">)</span></span></span> 等于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>a <span class="sy2">+</span><span class="sy1">=</span> n<span class="br0">)</span></span></span> 。</li>
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<li>对于二个 <code>D</code> 类型正值 <code>x</code> 与 <code>y</code> ，若 <span class="t-c"><span class="mw-geshi cpp source-cpp">I<span class="br0">(</span>a <span class="sy2">+</span> D<span class="br0">(</span>x <span class="sy2">+</span> y<span class="br0">)</span><span class="br0">)</span></span></span> 为良定义，则 <span class="t-c"><span class="mw-geshi cpp source-cpp">I<span class="br0">(</span>a <span class="sy2">+</span> D<span class="br0">(</span>x <span class="sy2">+</span> y<span class="br0">)</span><span class="br0">)</span></span></span> 等于 <span class="t-c"><span class="mw-geshi cpp source-cpp">I<span class="br0">(</span>I<span class="br0">(</span>a <span class="sy2">+</span> x<span class="br0">)</span> <span class="sy2">+</span> y<span class="br0">)</span></span></span> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp">I<span class="br0">(</span>a <span class="sy2">+</span> D<span class="br0">(</span><span class="nu0">0</span><span class="br0">)</span><span class="br0">)</span></span></span> 等于 <code>a</code> 。</li>
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<li>若 <span class="t-c"><span class="mw-geshi cpp source-cpp">I<span class="br0">(</span>a <span class="sy2">+</span> D<span class="br0">(</span>n <span class="sy2">-</span> <span class="nu0">1</span><span class="br0">)</span><span class="br0">)</span></span></span> 为良定义，则 <span class="t-c"><span class="mw-geshi cpp source-cpp">I<span class="br0">(</span>a <span class="sy2">+</span> n<span class="br0">)</span></span></span> 等于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">[</span><span class="br0">]</span><span class="br0">(</span>I c<span class="br0">)</span> <span class="br0">{</span> <span class="kw1">return</span> <span class="sy2">++</span>c<span class="sy4">;</span> <span class="br0">}</span><span class="br0">(</span>I<span class="br0">(</span>a <span class="sy2">+</span> D<span class="br0">(</span>n <span class="sy2">-</span> <span class="nu0">1</span><span class="br0">)</span><span class="br0">)</span><span class="br0">)</span></span></span> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>b <span class="sy2">+</span><span class="sy1">=</span> <span class="sy2">-</span>n<span class="br0">)</span></span></span> 等于 <code>a</code> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>b <span class="sy2">-</span><span class="sy1">=</span> n<span class="br0">)</span></span></span> 等于 <code>a</code> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>b <span class="sy2">-</span><span class="sy1">=</span> n<span class="br0">)</span></span></span> 等于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-memory-addressof.html"><span class="kw757">std::<span class="me2">addressof</span></span></a><span class="br0">(</span>b<span class="br0">)</span></span></span> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp">I<span class="br0">(</span>b <span class="sy2">-</span> n<span class="br0">)</span></span></span> 等于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="br0">(</span>b <span class="sy2">-</span><span class="sy1">=</span> n<span class="br0">)</span></span></span> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp">D<span class="br0">(</span>b <span class="sy2">-</span> a<span class="br0">)</span></span></span> 等于 <code>n</code> 。</li>
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<li><span class="t-c"><span class="mw-geshi cpp source-cpp">D<span class="br0">(</span>a <span class="sy2">-</span> b<span class="br0">)</span></span></span> 等于 <span class="t-c"><span class="mw-geshi cpp source-cpp">D<span class="br0">(</span><span class="sy2">-</span>n<span class="br0">)</span></span></span> 。</li>
|
|
<li><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">bool</span><span class="br0">(</span>a <span class="sy1"><=</span> b<span class="br0">)</span></span></span> 为 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw2">true</span></span></span> 。</li>
|
|
</ul>
|
|
</div>
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|
<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">
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|
<tr class="t-dsc-hitem">
|
|
<td>成员类型</td>
|
|
<td>定义</td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>iterator_concept</code></td>
|
|
<td>若 <code>W</code> 实现 <code><i>advanceable</i></code> 则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::random_access_iterator_tag</a></span> 。<br />
|
|
否则若 <code>W</code> 实现 <code><i>decrementable</i></code> 则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::bidirectional_iterator_tag</a></span> 。<br />
|
|
否则若 <code>W</code> 实现 <a href="cpp-iterator-incrementable.html"><code>incrementable</code></a> 则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::forward_iterator_tag</a></span> 。<br />
|
|
否则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::input_iterator_tag</a></span> 。</td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>iterator_category</code></td>
|
|
<td>若 <code>W</code> 实现 <a href="cpp-iterator-incrementable.html"><code>incrementable</code></a> 则为 <span class="t-lc"><a href="cpp-iterator-iterator_tags.html">std::input_iterator_tag</a></span> 。<br />
|
|
否则无成员类型 <code>iterator_category</code> 。</td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>value_type</code></td>
|
|
<td><code>W</code></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td><code>difference_type</code></td>
|
|
<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iota-diff-t*/</span><span class="sy1"><</span>W<span class="sy1">></span></span></span></td>
|
|
</tr>
|
|
</table>
|
|
<p>注意： <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iterator*/</span></span></span> 是</p>
|
|
<ul>
|
|
<li><a href="cpp-iterator-random_access_iterator.html"><code>random_access_iterator</code></a> ，若 <span class="t-c"><span class="mw-geshi cpp source-cpp">W</span></span> 实现 <code><i>advanceable</i></code> ，</li>
|
|
<li><a href="cpp-iterator-bidirectional_iterator.html"><code>bidirectional_iterator</code></a> ，若 <span class="t-c"><span class="mw-geshi cpp source-cpp">W</span></span> 实现 <code><i>decrementable</i></code> ，</li>
|
|
<li><a href="cpp-iterator-forward_iterator.html"><code>forward_iterator</code></a> ，若 <span class="t-c"><span class="mw-geshi cpp source-cpp">W</span></span> 实现 <a href="cpp-iterator-incrementable.html"><code>incrementable</code></a> ，</li>
|
|
<li>否则为 <a href="cpp-iterator-input_iterator.html"><code>input_iterator</code></a> 。</li>
|
|
</ul>
|
|
<p>然而，若 <code>W</code> 实现 <a href="cpp-iterator-incrementable.html"><code>incrementable</code></a> 则它仅满足<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">老式输入迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyInputIterator)</span></a> ，否则不满足<a href="cpp-named_req-InputIterator.html"><span style="font-style:italic">老式输入迭代器</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(LegacyInputIterator)</span></a> 。</p>
|
|
<h3><span class="mw-headline" id=".E6.95.B0.E6.8D.AE.E6.88.90.E5.91.98">数据成员</span></h3>
|
|
<p>此迭代器类型的典型实现仅保有一个 <code>W</code> 类型的数据成员（此处示为 <span class="t-c"><span class="mw-geshi cpp source-cpp">value_</span></span> ）：用于解引用的值。</p>
|
|
<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">成员函数</span></h3>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::ranges::iota_view::iterator::iterator"><span style="font-size:0.7em; line-height:130%">std::ranges::iota_view::<i>iterator</i>::</span><i>iterator</i></span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="coMULTI">/*iterator*/</span><span class="br0">(</span><span class="br0">)</span> requires std<span class="sy4">::</span><span class="me2">default_initializable</span><span class="sy1"><</span>W<span class="sy1">></span> <span class="sy1">=</span> <span class="kw1">default</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(1)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="kw1">explicit</span> <span class="coMULTI">/*iterator*/</span><span class="br0">(</span> W value <span class="br0">)</span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 经由其默认成员初始化器（ <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy1">=</span> W<span class="br0">(</span><span class="br0">)</span></span></span> ）值初始化仅用于阐释的数据成员 <code>value_</code> 。</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 以 <code>value</code> 初始化仅用于阐释的数据成员 <code>value_</code> 。此值将由 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">*</span></span></span> 返回，并为 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy2">++</span></span></span> 所自增。</div>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::ranges::iota_view::iterator::operator.2A"><span style="font-size:0.7em; line-height:130%">std::ranges::iota_view::<i>iterator</i>::</span>operator*</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> W operator<span class="sy2">*</span><span class="br0">(</span><span class="br0">)</span> <span class="kw4">const</span><br />
|
|
<span class="kw1">noexcept</span><span class="br0">(</span><a href="cpp-types-is_copy_constructible.html"><span class="kw537">std::<span class="me2">is_nothrow_copy_constructible_v</span></span></a><span class="sy1"><</span>W<span class="sy1">></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-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>按值返回当前值（换言之，这是只读视图）。</p>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::ranges::iota_view::iterator::operator.2B.2B"><span style="font-size:0.7em; line-height:130%">std::ranges::iota_view::<i>iterator</i>::</span>operator++</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> operator<span class="sy2">++</span><span class="br0">(</span><span class="br0">)</span></span></div>
|
|
</td>
|
|
<td>(1)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="kw4">void</span> operator<span class="sy2">++</span><span class="br0">(</span><span class="kw4">int</span><span class="br0">)</span></span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span> operator<span class="sy2">++</span><span class="br0">(</span><span class="kw4">int</span><span class="br0">)</span> requires std<span class="sy4">::</span><span class="me2">incrementable</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(3)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">++</span>value_<span class="sy4">;</span> <span class="kw1">return</span> <span class="sy2">*</span>this<span class="sy4">;</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">++</span>value_<span class="sy4">;</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">3)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">auto</span> tmp <span class="sy1">=</span> <span class="sy2">*</span>this<span class="sy4">;</span> <span class="sy2">++</span>value_<span class="sy4">;</span> <span class="kw1">return</span> tmp<span class="sy4">;</span></span></span> 。</div>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::ranges::iota_view::iterator::operator--"><span style="font-size:0.7em; line-height:130%">std::ranges::iota_view::<i>iterator</i>::</span>operator--</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> operator<span class="sy2">--</span><span class="br0">(</span><span class="br0">)</span> requires <span class="coMULTI">/*decrementable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(1)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span>operator<span class="sy2">--</span><span class="br0">(</span><span class="kw4">int</span><span class="br0">)</span> requires <span class="coMULTI">/*decrementable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">--</span>value_<span class="sy4">;</span> <span class="kw1">return</span> <span class="sy2">*</span>this<span class="sy4">;</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw4">auto</span> tmp <span class="sy1">=</span> <span class="sy2">*</span>this<span class="sy4">;</span> <span class="sy2">--</span>value_<span class="sy4">;</span> <span class="kw1">return</span> tmp<span class="sy4">;</span></span></span> 。</div>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::ranges::iota_view::iterator::operator.2B.3D"><span style="font-size:0.7em; line-height:130%">std::ranges::iota_view::<i>iterator</i>::</span>operator+=</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> operator<span class="sy2">+</span><span class="sy1">=</span><span class="br0">(</span> difference_type n <span class="br0">)</span><br />
|
|
requires <span class="coMULTI">/*advanceable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>若 <code>W</code> 为无符号整式，则在 <code>n</code> 非负时进行 <span class="t-c"><span class="mw-geshi cpp source-cpp">value_ <span class="sy2">+</span><span class="sy1">=</span> <span class="kw1">static_cast</span><span class="sy1"><</span>W<span class="sy1">></span><span class="br0">(</span>n<span class="br0">)</span></span></span> ，否则进行 <span class="t-c"><span class="mw-geshi cpp source-cpp">value <span class="sy2">-</span><span class="sy1">=</span> <span class="kw1">static_cast</span><span class="sy1"><</span>W<span class="sy1">></span><span class="br0">(</span><span class="sy2">-</span>n<span class="br0">)</span></span></span> ，然后返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 。</p>
|
|
<p>否则等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">value_ <span class="sy2">+</span><span class="sy1">=</span> n<span class="sy4">;</span> <span class="kw1">return</span> <span class="sy2">*</span>this<span class="sy4">;</span></span></span> 。</p>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::ranges::iota_view::iterator::operator-.3D"><span style="font-size:0.7em; line-height:130%">std::ranges::iota_view::<i>iterator</i>::</span>operator-=</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> operator<span class="sy2">-</span><span class="sy1">=</span><span class="br0">(</span> difference_type n <span class="br0">)</span><br />
|
|
requires <span class="coMULTI">/*advanceable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>若 <code>W</code> 为无符号整式，则在 <code>n</code> 非负时进行 <span class="t-c"><span class="mw-geshi cpp source-cpp">value_ <span class="sy2">-</span><span class="sy1">=</span> <span class="kw1">static_cast</span><span class="sy1"><</span>W<span class="sy1">></span><span class="br0">(</span>n<span class="br0">)</span></span></span> ，否则进行 <span class="t-c"><span class="mw-geshi cpp source-cpp">value <span class="sy2">+</span><span class="sy1">=</span> <span class="kw1">static_cast</span><span class="sy1"><</span>W<span class="sy1">></span><span class="br0">(</span><span class="sy2">-</span>n<span class="br0">)</span></span></span> ，然后返回 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">*</span>this</span></span> 。</p>
|
|
<p>否则等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">value_ <span class="sy2">-</span><span class="sy1">=</span> n<span class="sy4">;</span> <span class="kw1">return</span> <span class="sy2">*</span>this<span class="sy4">;</span></span></span> 。</p>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="std::ranges::iota_view::iterator::operator.5B.5D"><span style="font-size:0.7em; line-height:130%">std::ranges::iota_view::<i>iterator</i>::</span>operator[]</span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">constexpr</span> W operator<span class="br0">[</span><span class="br0">]</span><span class="br0">(</span> difference_type n <span class="br0">)</span> <span class="kw4">const</span><br />
|
|
requires <span class="coMULTI">/*advanceable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
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</table>
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<p>等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> W<span class="br0">(</span>value_ <span class="sy2">+</span> n<span class="br0">)</span><span class="sy4">;</span></span></span> 。</p>
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</div>
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<h3><span class="mw-headline" id=".E9.9D.9E.E6.88.90.E5.91.98.E5.87.BD.E6.95.B0">非成员函数</span></h3>
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<div class="t-member">
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<h2><span class="mw-headline" id="operator.3D.3D.2C_.3C.2C_.3E.2C_.3C.3D.2C_.3E.3D.2C_.3C.3D.3E.28std::ranges::iota_view::iterator.29">operator==, <, >, <=, >=, <=><small>(std::ranges::iota_view::<i>iterator</i>)</small></span></h2>
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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dcl t-since-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">==</span> <span class="br0">(</span><span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> x, <span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> y<span class="br0">)</span><br />
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requires std<span class="sy4">::</span><span class="me2">equality_comparable</span><span class="sy1"><</span>W<span class="sy1">></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-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1"><</span> <span class="br0">(</span><span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> x, <span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> y<span class="br0">)</span><br />
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requires std<span class="sy4">::</span><span class="me2">totally_ordered</span><span class="sy1"><</span>W<span class="sy1">></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-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">></span> <span class="br0">(</span><span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> x, <span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> y<span class="br0">)</span><br />
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requires std<span class="sy4">::</span><span class="me2">totally_ordered</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
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</td>
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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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</tr>
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<tr class="t-dcl t-since-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1"><=</span> <span class="br0">(</span><span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> x, <span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> y<span class="br0">)</span><br />
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requires std<span class="sy4">::</span><span class="me2">totally_ordered</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
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</td>
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<td>(4)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
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</tr>
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<tr class="t-dcl t-since-cxx20">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1">>=</span> <span class="br0">(</span><span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> x, <span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> y<span class="br0">)</span><br />
|
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requires std<span class="sy4">::</span><span class="me2">totally_ordered</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
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</td>
|
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<td>(5)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
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</tr>
|
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<tr class="t-dcl t-since-cxx20">
|
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<td>
|
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<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="kw4">bool</span> operator<span class="sy1"><=></span><span class="br0">(</span><span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> x, <span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> y<span class="br0">)</span><br />
|
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requires std<span class="sy4">::</span><span class="me2">totally_ordered</span><span class="sy1"><</span>W<span class="sy1">></span> <span class="sy3">&&</span> std<span class="sy4">::</span><span class="me2">three_way_comparable</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
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</td>
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<td>(6)</td>
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<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
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</tr>
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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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</table>
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<div class="t-li1"><span class="t-li">1)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> x.<span class="me1">value_</span> <span class="sy1">==</span> y.<span class="me1">value_</span><span class="sy4">;</span></span></span> 。</div>
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<div class="t-li1"><span class="t-li">2)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> x.<span class="me1">value_</span> <span class="sy1"><</span> y.<span class="me1">value_</span><span class="sy4">;</span></span></span> 。</div>
|
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<div class="t-li1"><span class="t-li">3)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> y <span class="sy1"><</span> x<span class="sy4">;</span></span></span> 。</div>
|
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<div class="t-li1"><span class="t-li">4)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> <span class="sy3">!</span><span class="br0">(</span>y <span class="sy1"><</span> x<span class="br0">)</span><span class="sy4">;</span></span></span> 。</div>
|
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<div class="t-li1"><span class="t-li">5)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> <span class="sy3">!</span><span class="br0">(</span>x <span class="sy1"><</span> y<span class="br0">)</span><span class="sy4">;</span></span></span> 。</div>
|
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<div class="t-li1"><span class="t-li">6)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> x.<span class="me1">value_</span> <span class="sy1"><=></span> y.<span class="me1">value_</span><span class="sy4">;</span></span></span>。</div>
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<p><code>!=</code> 运算符从 <code>operator==</code> <a href="cpp-language-operators.html#.E5.85.B3.E7.B3.BB.E8.BF.90.E7.AE.97.E7.AC.A6">合成</a>。</p>
|
|
<p>这些函数对通常<a href="cpp-language-unqualified_lookup.html">无限定</a>或<a href="cpp-language-qualified_lookup.html">有限定查找</a>不可见，而只能在 <code><i>iterator</i></code> 为参数的关联类时由<a href="cpp-language-adl.html">实参依赖查找</a>找到。</p>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="operator.2B.28std::ranges::iota_view::iterator.29">operator+<small>(std::ranges::iota_view::<i>iterator</i>)</small></span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span> operator<span class="sy2">+</span><span class="br0">(</span> <span class="coMULTI">/*iterator*/</span> i, difference_type n <span class="br0">)</span><br />
|
|
requires <span class="coMULTI">/*advanceable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(1)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span> operator<span class="sy2">+</span><span class="br0">(</span> difference_type n, <span class="coMULTI">/*iterator*/</span> i <span class="br0">)</span><br />
|
|
requires <span class="coMULTI">/*advanceable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">i <span class="sy2">+</span><span class="sy1">=</span> n<span class="sy4">;</span> <span class="kw1">return</span> i<span class="sy4">;</span></span></span> 。</p>
|
|
<p>这些函数对通常<a href="cpp-language-unqualified_lookup.html">无限定</a>或<a href="cpp-language-qualified_lookup.html">有限定查找</a>不可见，而只能在 <code><i>iterator</i></code> 为参数的关联类时由<a href="cpp-language-adl.html">实参依赖查找</a>找到。</p>
|
|
</div>
|
|
<div class="t-member">
|
|
<h2><span class="mw-headline" id="operator-.28std::ranges::iota_view::iterator.29">operator-<small>(std::ranges::iota_view::<i>iterator</i>)</small></span></h2>
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> <span class="coMULTI">/*iterator*/</span> operator<span class="sy2">-</span><span class="br0">(</span> <span class="coMULTI">/*iterator*/</span> i, difference_type n <span class="br0">)</span><br />
|
|
requires <span class="coMULTI">/*advanceable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></span></div>
|
|
</td>
|
|
<td>(1)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx20">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw1">friend</span> <span class="kw4">constexpr</span> difference_type operator<span class="sy2">-</span><span class="br0">(</span> <span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> x,<br /></span>
|
|
<p> <span class="kw4">const</span> <span class="coMULTI">/*iterator*/</span><span class="sy3">&</span> y <span class="br0">)</span><br /></p>
|
|
requires <span class="coMULTI">/*advanceable*/</span><span class="sy1"><</span>W<span class="sy1">></span><span class="sy4">;</span></div>
|
|
</td>
|
|
<td>(2)</td>
|
|
<td><span class="t-mark-rev t-since-cxx20">(C++20 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<div class="t-li1"><span class="t-li">1)</span> 等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">i <span class="sy2">-</span><span class="sy1">=</span> n<span class="sy4">;</span> <span class="kw1">return</span> i<span class="sy4">;</span></span></span> 。</div>
|
|
<div class="t-li1"><span class="t-li">2)</span> 令 <code>D</code> 为 <code>difference_type</code> 。
|
|
<ul>
|
|
<li>若 <code>W</code> 为有符号整数式，等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> D<span class="br0">(</span>D<span class="br0">(</span>x.<span class="me1">value_</span><span class="br0">)</span> <span class="sy2">-</span> D<span class="br0">(</span>y.<span class="me1">value_</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span></span></span> 。</li>
|
|
<li>否则若 <code>W</code> 为无符号整数式，等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> y.<span class="me1">value_</span> <span class="sy1">></span> x.<span class="me1">value_</span> <span class="sy4">?</span> D<span class="br0">(</span><span class="sy2">-</span>D<span class="br0">(</span>y.<span class="me1">value_</span> <span class="sy2">-</span> x.<span class="me1">value_</span><span class="br0">)</span><span class="br0">)</span> <span class="sy4">:</span> D<span class="br0">(</span>x.<span class="me1">value_</span> <span class="sy2">-</span> y.<span class="me1">value_</span><span class="br0">)</span><span class="sy4">;</span></span></span> 。</li>
|
|
<li>否则等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="kw1">return</span> x.<span class="me1">value_</span> <span class="sy2">-</span> y.<span class="me1">value_</span><span class="sy4">;</span></span></span> 。</li>
|
|
</ul>
|
|
</div>
|
|
<p>这些函数对通常<a href="cpp-language-unqualified_lookup.html">无限定</a>或<a href="cpp-language-qualified_lookup.html">有限定查找</a>不可见，而只能在 <code><i>iterator</i></code> 为参数的关联类时由<a href="cpp-language-adl.html">实参依赖查找</a>找到。</p>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E7.BC.BA.E9.99.B7.E6.8A.A5.E5.91.8A">缺陷报告</span></h3>
|
|
<p>下列更改行为的缺陷报告追溯地应用于以前出版的 C++ 标准。</p>
|
|
<table class="dsctable" style="font-size:0.8em">
|
|
<tr>
|
|
<th>DR</th>
|
|
<th>应用于</th>
|
|
<th>出版时的行为</th>
|
|
<th>正确行为</th>
|
|
</tr>
|
|
<tr>
|
|
<td><a rel="nofollow" class="external text" href="https://wg21.link/P2259R1">P2259R1</a></td>
|
|
<td>C++20</td>
|
|
<td>始终定义成员 <code>iterator_category</code></td>
|
|
<td>仅若 <code>W</code> 满足 <a href="cpp-iterator-incrementable.html"><code>incrementable</code></a> 才定义</td>
|
|
</tr>
|
|
<tr>
|
|
<td><a rel="nofollow" class="external text" href="https://cplusplus.github.io/LWG/issue3580">LWG 3580</a></td>
|
|
<td>C++20</td>
|
|
<td><code>operator+</code> 与 <code>operator-</code> 复制迭代器</td>
|
|
<td>使之移动迭代器</td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|