libs/hana/doc/html/structboost_1_1hana_1_1embedding.html

   1 <!--
   2 Copyright Louis Dionne 2013-2017
   3 Distributed under the Boost Software License, Version 1.0.
   4 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
   5 -->
   6 <!-- boost-no-inspect -->
   7 <!-- HTML header for doxygen 1.8.9.1-->
   8 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
   9 <html xmlns="http://www.w3.org/1999/xhtml">
  10 <head>
  11 <meta http-equiv="Content-Type" content="text/xhtml;charset=UTF-8"/>
  12 <meta http-equiv="X-UA-Compatible" content="IE=9"/>
  13 <meta name="generator" content="Doxygen 1.8.11"/>
  14 <title>Boost.Hana: boost::hana::embedding&lt; bool &gt; Struct Template Reference</title>
  15 <link href="tabs.css" rel="stylesheet" type="text/css"/>
  16 <script type="text/javascript" src="jquery.js"></script>
  17 <script type="text/javascript" src="dynsections.js"></script>
  18 <link href="navtree.css" rel="stylesheet" type="text/css"/>
  19 <script type="text/javascript" src="resize.js"></script>
  20 <script type="text/javascript" src="navtreedata.js"></script>
  21 <script type="text/javascript" src="navtree.js"></script>
  22 <script type="text/javascript">
  23   $(document).ready(initResizable);
  24   $(window).load(resizeHeight);
  25 </script>
  26 <link href="search/search.css" rel="stylesheet" type="text/css"/>
  27 <script type="text/javascript" src="search/searchdata.js"></script>
  28 <script type="text/javascript" src="search/search.js"></script>
  29 <script type="text/javascript">
  30   $(document).ready(function() { init_search(); });
  31 </script>
  32 <script type="text/x-mathjax-config">
  33   MathJax.Hub.Config({
  34     extensions: ["tex2jax.js"],
  35     jax: ["input/TeX","output/HTML-CSS"],
  36 });
  37 // Copyright Louis Dionne 2013-2017
  38 // Distributed under the Boost Software License, Version 1.0.
  39 // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
  40 MathJax.Hub.Config({
  41     "HTML-CSS": {
  42         linebreaks: {
  43             automatic: true,
  44             width: "75% container"
  45         }
  46     }
  47 });
  48 </script><script type="text/javascript" src="https://cdn.mathjax.org/mathjax/latest/MathJax.js"></script>
  49 <link href="doxygen.css" rel="stylesheet" type="text/css" />
  50 <!-- Additional javascript for drawing charts. -->
  51 <script type="text/javascript" src="highcharts.js"></script>
  52 <script type="text/javascript" src="highcharts-data.js"></script>
  53 <script type="text/javascript" src="highcharts-exporting.js"></script>
  54 <script type="text/javascript" src="chart.js"></script>
  55 <script type="text/javascript" src="hana.js"></script>
  56 </head>
  57 <body>
  58 <div id="top"><!-- do not remove this div, it is closed by doxygen! -->
  59 <div id="titlearea">
  60 <table cellspacing="0" cellpadding="0">
  61  <tbody>
  62  <tr style="height: 56px;">
  63   <td id="projectlogo"><img alt="Logo" src="Boost.png"/></td>
  64   <td style="padding-left: 0.5em;">
  65    <div id="projectname">Boost.Hana
  66    &#160;<span id="projectnumber">1.1.0</span>
  67    </div>
  68    <div id="projectbrief">Your standard library for metaprogramming</div>
  69   </td>
  70    <td>        <div id="MSearchBox" class="MSearchBoxInactive">
  71         <span class="left">
  72           <img id="MSearchSelect" src="search/mag_sel.png"
  73                onmouseover="return searchBox.OnSearchSelectShow()"
  74                onmouseout="return searchBox.OnSearchSelectHide()"
  75                alt=""/>
  76           <input type="text" id="MSearchField" value="Search" accesskey="S"
  77                onfocus="searchBox.OnSearchFieldFocus(true)"
  78                onblur="searchBox.OnSearchFieldFocus(false)"
  79                onkeyup="searchBox.OnSearchFieldChange(event)"/>
  80           </span><span class="right">
  81             <a id="MSearchClose" href="javascript:searchBox.CloseResultsWindow()"><img id="MSearchCloseImg" border="0" src="search/close.png" alt=""/></a>
  82           </span>
  83         </div>
  84 </td>
  85  </tr>
  86  </tbody>
  87 </table>
  88 </div>
  89 <!-- end header part -->
  90 <!-- Generated by Doxygen 1.8.11 -->
  91 <script type="text/javascript">
  92 var searchBox = new SearchBox("searchBox", "search",false,'Search');
  93 </script>
  94 </div><!-- top -->
  95 <div id="side-nav" class="ui-resizable side-nav-resizable">
  96   <div id="nav-tree">
  97     <div id="nav-tree-contents">
  98       <div id="nav-sync" class="sync"></div>
  99     </div>
 100   </div>
 101   <div id="splitbar" style="-moz-user-select:none;"
 102        class="ui-resizable-handle">
 103   </div>
 104 </div>
 105 <script type="text/javascript">
 106 $(document).ready(function(){initNavTree('structboost_1_1hana_1_1embedding.html','');});
 107 </script>
 108 <div id="doc-content">
 109 <!-- window showing the filter options -->
 110 <div id="MSearchSelectWindow"
 111      onmouseover="return searchBox.OnSearchSelectShow()"
 112      onmouseout="return searchBox.OnSearchSelectHide()"
 113      onkeydown="return searchBox.OnSearchSelectKey(event)">
 114 </div>
 115
 116 <!-- iframe showing the search results (closed by default) -->
 117 <div id="MSearchResultsWindow">
 118 <iframe src="javascript:void(0)" frameborder="0"
 119         name="MSearchResults" id="MSearchResults">
 120 </iframe>
 121 </div>
 122
 123 <div class="header">
 124   <div class="headertitle">
 125 <div class="title">boost::hana::embedding&lt; bool &gt; Struct Template Reference<div class="ingroups"><a class="el" href="group__group-core.html">Core</a></div></div>  </div>
 126 </div><!--header-->
 127 <div class="contents">
 128 <a name="details" id="details"></a><h2 class="groupheader">Description</h2>
 129 <div class="textblock"><h3>template&lt;bool = true&gt;<br />
 130 struct boost::hana::embedding&lt; bool &gt;</h3>
 131
 132 <p>Marks a conversion between data types as being an embedding. </p>
 133 <p>To mark a conversion between two data types <code>To</code> and <code>From</code> as an embedding, simply use <code>embedding&lt;true&gt;</code> (or simply <code>embedding&lt;&gt;</code>) as a base class of the corresponding <code>to_impl</code> specialization. If a <code>to_impl</code> specialization does not inherit <code>embedding&lt;true&gt;</code> or <code>embedding&lt;&gt;</code>, then it is not considered an embedding by the <code><a class="el" href="structboost_1_1hana_1_1is__embedded.html" title="Returns whether a data type can be embedded into another data type. ">is_embedded</a></code> metafunction.</p>
 134 <blockquote class="doxtable">
 135 <h4>Tip</h4>
 136 <p>The boolean template parameter is useful for marking a conversion as an embedding only when some condition is satisfied. </p>
 137 </blockquote>
 138 <h2>Example </h2>
 139 <div class="fragment"><div class="line"><span class="comment">// Copyright Louis Dionne 2013-2017</span></div><div class="line"><span class="comment">// Distributed under the Boost Software License, Version 1.0.</span></div><div class="line"><span class="comment">// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)</span></div><div class="line"></div><div class="line"><span class="preprocessor">#include &lt;<a class="code" href="assert_8hpp.html">boost/hana/assert.hpp</a>&gt;</span></div><div class="line"><span class="preprocessor">#include &lt;<a class="code" href="core_2to_8hpp.html">boost/hana/core/to.hpp</a>&gt;</span></div><div class="line"><span class="preprocessor">#include &lt;<a class="code" href="core_2when_8hpp.html">boost/hana/core/when.hpp</a>&gt;</span></div><div class="line"></div><div class="line"><span class="preprocessor">#include &lt;vector&gt;</span></div><div class="line"><span class="keyword">namespace </span>hana = <a class="code" href="namespaceboost_1_1hana.html">boost::hana</a>;</div><div class="line"></div><div class="line"></div><div class="line"><span class="keyword">namespace </span><a class="code" href="namespaceboost.html">boost</a> { <span class="keyword">namespace </span>hana {</div><div class="line">    <span class="keyword">template</span> &lt;<span class="keyword">typename</span> To, <span class="keyword">typename</span> From&gt;</div><div class="line">    <span class="keyword">struct </span>to_impl&lt;<a class="code" href="namespacestd.html">std</a>::vector&lt;To&gt;, std::vector&lt;From&gt;,</div><div class="line">        when&lt;is_convertible&lt;From, To&gt;::value&gt;&gt;</div><div class="line">        : embedding&lt;is_embedded&lt;From, To&gt;::value&gt;</div><div class="line">    {</div><div class="line">        <span class="keyword">static</span> std::vector&lt;To&gt; <a class="code" href="group__group-functional.html#ga30027c383676084be151ef3c6cf2829f">apply</a>(std::vector&lt;From&gt; <span class="keyword">const</span>&amp; xs) {</div><div class="line">            std::vector&lt;To&gt; result;</div><div class="line">            <span class="keywordflow">for</span> (<span class="keyword">auto</span> <span class="keyword">const</span>&amp; x: xs)</div><div class="line">                result.push_back(to&lt;To&gt;(x));</div><div class="line">            <span class="keywordflow">return</span> result;</div><div class="line">        }</div><div class="line">    };</div><div class="line">}}</div><div class="line"></div><div class="line"><span class="keywordtype">int</span> main() {</div><div class="line">    <a class="code" href="group__group-assertions.html#ga29b2b21ffa5513e5b706c50ffee980af">BOOST_HANA_RUNTIME_CHECK</a>(</div><div class="line">        <a class="code" href="group__group-core.html#gadc70755c1d059139297814fb3bfeb91e">hana::to</a>&lt;std::vector&lt;int&gt;&gt;(std::vector&lt;float&gt;{1.1, 2.2, 3.3})</div><div class="line">                        ==</div><div class="line">        std::vector&lt;int&gt;{1, 2, 3}</div><div class="line">    );</div><div class="line"></div><div class="line">    static_assert(!hana::is_embedded&lt;std::vector&lt;float&gt;, std::vector&lt;int&gt;&gt;{}, <span class="stringliteral">&quot;&quot;</span>);</div><div class="line">}</div></div><!-- fragment --> </div></div><!-- contents -->
 140 </div><!-- doc-content -->
 141 <!--
 142 Copyright Louis Dionne 2013-2017
 143 Distributed under the Boost Software License, Version 1.0.
 144 (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
 145 -->
 146 <!-- boost-no-inspect -->
 147 <!-- HTML footer for doxygen 1.8.9.1-->
 148 <!-- start footer part -->
 149 <div id="nav-path" class="navpath"><!-- id is needed for treeview function! -->
 150   <ul>
 151     <li class="navelem"><a class="el" href="namespaceboost.html">boost</a></li><li class="navelem"><a class="el" href="namespaceboost_1_1hana.html">hana</a></li><li class="navelem"><a class="el" href="structboost_1_1hana_1_1embedding.html">embedding</a></li>
 152   </ul>
 153 </div>
 154 </body>
 155 </html>