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+                C++ 20 实现 string split
+            
+            
+        </div>
+        <span class="post-date">
+            May 12, 2023
+        </span>
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+    <div class="post-content">
+    <p>C++20引入了范围库ranges，其中提供的两个范围适配器std::split、std::lazy_split可以使我们以一种更为优雅的形式实现split:</p>
+<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br><span class="line">4</span><br><span class="line">5</span><br><span class="line">6</span><br><span class="line">7</span><br><span class="line">8</span><br><span class="line">9</span><br><span class="line">10</span><br><span class="line">11</span><br><span class="line">12</span><br><span class="line">13</span><br><span class="line">14</span><br><span class="line">15</span><br><span class="line">16</span><br><span class="line">17</span><br><span class="line">18</span><br><span class="line">19</span><br><span class="line">20</span><br><span class="line">21</span><br><span class="line">22</span><br><span class="line">23</span><br><span class="line">24</span><br><span class="line">25</span><br><span class="line">26</span><br><span class="line">27</span><br><span class="line">28</span><br><span class="line">29</span><br><span class="line">30</span><br><span class="line">31</span><br></pre></td><td class="code"><pre><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;concept&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;ranges&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;algorithm&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;format&gt;</span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string">&lt;iostream&gt;</span></span></span><br><span class="line"></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> stdr  std::ranges</span></span><br><span class="line"><span class="meta">#<span class="keyword">define</span> stdrv std::ranges::views</span></span><br><span class="line"></span><br><span class="line"><span class="keyword">template</span>&lt;<span class="keyword">template</span>&lt;<span class="keyword">typename</span>&gt; <span class="keyword">typename</span> Container = std::vector, <span class="keyword">typename</span> Arg = std::string_view&gt;</span><br><span class="line"><span class="keyword">auto</span> <span class="built_in">Split</span>(std::string_view str, std::string_view delimiter)</span><br><span class="line">&#123;</span><br><span class="line">	Container&lt;Arg&gt; myCont;</span><br><span class="line">	<span class="keyword">auto</span> temp = str </span><br><span class="line">		| stdrv::<span class="built_in">split</span>(delimiter)</span><br><span class="line">		| stdrv::<span class="built_in">transform</span>([](<span class="keyword">auto</span>&amp;&amp; r)</span><br><span class="line">			&#123;</span><br><span class="line">				<span class="keyword">return</span> <span class="built_in">Arg</span>(std::<span class="built_in">addressof</span>(*r.<span class="built_in">begin</span>()), stdr::<span class="built_in">distance</span>(r));</span><br><span class="line">			&#125;);</span><br><span class="line">	<span class="keyword">auto</span> iter = std::<span class="built_in">inserter</span>(myCont, myCont.<span class="built_in">end</span>());</span><br><span class="line">	stdr::for_each(temp, [&amp;](<span class="keyword">auto</span>&amp;&amp; x) &#123; iter = &#123;x.<span class="built_in">begin</span>(), x.<span class="built_in">end</span>()&#125;; &#125;);</span><br><span class="line">	<span class="keyword">return</span> myCont;</span><br><span class="line">&#125;</span><br><span class="line"><span class="function"><span class="type">int</span> <span class="title">main</span><span class="params">()</span></span></span><br><span class="line"><span class="function"></span>&#123;</span><br><span class="line">	std::string str = <span class="string">&quot;Hello233C++20233and233New233Spilt&quot;</span>;</span><br><span class="line">	std::string delimiter = <span class="string">&quot;233&quot;</span>;</span><br><span class="line">	<span class="keyword">auto</span>&amp;&amp; strCont = <span class="built_in">Split</span>&lt;std::list, std::string&gt;(str, delimiter);</span><br><span class="line">	stdr::for_each(strCont, [](<span class="keyword">auto</span>&amp;&amp; x) &#123; std::cout &lt;&lt; std::format(<span class="string">&quot;&#123;&#125; &quot;</span>, x); &#125;);</span><br><span class="line">&#125;</span><br><span class="line"><span class="comment">//output: Hello C++20 and New Spilt</span></span><br></pre></td></tr></table></figure>
+
+<p>C++20没有提供关键的 <code>ranges::to&lt;container&gt;</code>函数，导致demo中还需要额外封装并手写for_each来写入数据，等到C++23实装了该函数，split的实现会比现在简洁优雅的多，真正做到方便泛用、无需封装：</p>
+<figure class="highlight cpp"><table><tr><td class="gutter"><pre><span class="line">1</span><br><span class="line">2</span><br><span class="line">3</span><br></pre></td><td class="code"><pre><span class="line"><span class="keyword">auto</span>&amp;&amp; strCont = str</span><br><span class="line">	| stdrv::<span class="built_in">lazy_split</span>(delimiter)</span><br><span class="line">	| stdr ::to&lt;std::vector&lt;std::string&gt;&gt;;</span><br></pre></td></tr></table></figure>
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