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diff --git a/2024/05/12/C-20-实现-string-split/index.html b/2024/05/12/C-20-实现-string-split/index.html new file mode 100644 index 00000000..9a3749b3 --- /dev/null +++ b/2024/05/12/C-20-实现-string-split/index.html @@ -0,0 +1,237 @@ +<!DOCTYPE html> +<html lang="en"> + <head> + <meta charset="UTF-8"> +<meta name="viewport" + content="width=device-width, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"> +<meta http-equiv="X-UA-Compatible" content="ie=edge"> + + <meta name="author" content="韩暮秋"> + + + <meta name="subtitle" content="暮秋小屋"> + + + <meta name="description" content="这里是暮秋小屋，思念和灵感的寄存处"> + + + <meta name="keywords" content="韩暮秋,MuqiuHan"> + + + + +<title>C++ 20 实现 string split | 暮秋小屋</title> + + + + + +<style> + @import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Noto+Sans+SC:wght@300;400;500;700&family=Roboto+Mono&display=swap'); +</style> + + + + <!-- stylesheets list from _config.yml --> + + <link rel="stylesheet" href="/css/style.css"> + + + + + + <!-- scripts list from _config.yml --> + + <script src="/js/frame.js"></script> + + + + + + <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script> + <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script> + + + + + + + + <meta name="generator" content="Hexo 6.3.0"></head> + <body> + <div class="mask-border"> + </div> + + <div class="wrapper"> + + <div class="header"> + <div class="flex-container"> + <div class="header-inner"> + <div class="site-brand-container"> + <a href="/"> + + 暮秋小屋 + + </a> + </div> + <div id="menu-btn" class="menu-btn" onclick="toggleMenu()"> + Menu + </div> + <nav class="site-nav"> + <ul class="menu-list"> + + + <li class="menu-item"> + <a href="/">主页</a> + </li> + + + + <li class="menu-item"> + <a href="/categories/gallery/">日记本</a> + </li> + + + + <li class="menu-item"> + <a href="/tags/Medicine/">医学</a> + </li> + + + + <li class="menu-item"> + <a href="/tags/Technique/">计算机科学</a> + </li> + + + + <li class="menu-item"> + <a href="/tags/Life/">生活</a> + </li> + + + + <li class="menu-item"> + <a href="/about">关于</a> + </li> + + + + </ul> + </nav> + </div> + </div> +</div> + + + <div class="main"> + <div class="flex-container"> + <article id="post"> + + + <div class="post-head"> + <div class="post-info"> + <div class="tag-list"> + + + <span class="post-tag"> + <a href="/tags/Technique/"> + Technique + </a> + </span> + + <span class="post-tag"> + <a href="/tags/C/"> + C++ + </a> + </span> + + + </div> + <div class="post-title"> + + + C++ 20 实现 string split + + + </div> + <span class="post-date"> + May 12, 2024 + </span> + </div> + <div class="post-img"> + + <div class="h-line-primary"></div> + + </div> +</div> + <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"><concept></span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><ranges></span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><algorithm></span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><format></span></span></span><br><span class="line"><span class="meta">#<span class="keyword">include</span> <span class="string"><iostream></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><<span class="keyword">template</span><<span class="keyword">typename</span>> <span class="keyword">typename</span> Container = std::vector, <span class="keyword">typename</span> Arg = std::string_view></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">{</span><br><span class="line"> Container<Arg> 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>&& r)</span><br><span class="line"> {</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"> });</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, [&](<span class="keyword">auto</span>&& x) { iter = {x.<span class="built_in">begin</span>(), x.<span class="built_in">end</span>()}; });</span><br><span class="line"> <span class="keyword">return</span> myCont;</span><br><span class="line">}</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>{</span><br><span class="line"> std::string str = <span class="string">"Hello233C++20233and233New233Spilt"</span>;</span><br><span class="line"> std::string delimiter = <span class="string">"233"</span>;</span><br><span class="line"> <span class="keyword">auto</span>&& strCont = <span class="built_in">Split</span><std::list, std::string>(str, delimiter);</span><br><span class="line"> stdr::for_each(strCont, [](<span class="keyword">auto</span>&& x) { std::cout << std::format(<span class="string">"{} "</span>, x); });</span><br><span class="line">}</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<container></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>&& strCont = str</span><br><span class="line"> | stdrv::<span class="built_in">lazy_split</span>(delimiter)</span><br><span class="line"> | stdr ::to<std::vector<std::string>>;</span><br></pre></td></tr></table></figure> +</div> + +<script> + window.onload = detectors(); +</script> + <div class="post-footer"> + <div class="h-line-primary"></div> + <nav class="post-nav"> + <div class="prev-item"> + + <div class="icon arrow-left"></div> + <div class="post-link"> + <a href="/2024/05/13/%E7%BB%99%E5%B0%B8%E4%BD%93%E4%B8%8A-ECMO-%E5%B9%B6%E7%BB%B4%E6%8C%81%E5%BF%83%E8%B7%B3/">Prev</a> + </div> + + </div> + <div class="next-item"> + + <div class="icon arrow-right"></div> + <div class="post-link"> + <a href="/2024/05/11/C-vector-%E7%9A%84-push-back-%E5%92%8C-emplace-back/">Next</a> + </div> + + </div> + </nav> +</div> + + + <div class="post-comment"> + + + + + + + +</div> + + +</article> + </div> + </div> + + <div class="footer"> + <div class="flex-container"> + <div class="footer-text"> + + + | + + + 希望路过的人可以添点柴火让这里暖和点 + + </div> + </div> +</div> + + </div> + + + + + </body> +</html> |