libs/gil/doc/html/design/concepts.html

   1
   2
   3 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
   4   "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
   5 <html xmlns="http://www.w3.org/1999/xhtml">
   6   <head>
   7     <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
   8
   9     <title>Concepts - Boost.GIL  documentation</title>
  10     <link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
  11     <link rel="stylesheet" href="../_static/style.css" type="text/css" />
  12     <script type="text/javascript">
  13       var DOCUMENTATION_OPTIONS = {
  14           URL_ROOT:    '../',
  15           VERSION:     '',
  16           COLLAPSE_MODINDEX: false,
  17           FILE_SUFFIX: '.html'
  18       };
  19     </script>
  20     <script type="text/javascript" src="../_static/jquery.js"></script>
  21     <script type="text/javascript" src="../_static/underscore.js"></script>
  22     <script type="text/javascript" src="../_static/doctools.js"></script>
  23     <link rel="index" title="Index" href="../genindex.html" />
  24     <link rel="search" title="Search" href="../search.html" />
  25     <link rel="top" title="Boost.GIL  documentation" href="../index.html" />
  26     <link rel="up" title="Design Guide" href="index.html" />
  27     <link rel="next" title="Point" href="point.html" />
  28     <link rel="prev" title="Basics" href="basics.html" />
  29   </head>
  30   <body>
  31     <div class="header">
  32     <table border="0" cellpadding="7" cellspacing="0" width="100%" summary=
  33     "header">
  34       <tr>
  35         <td valign="top" width="300">
  36           <h3><a href="../index.html"><img
  37           alt="C++ Boost" src="../_static/gil.png" border="0"></a></h3>
  38         </td>
  39
  40         <td >
  41           <h1 align="center"><a href="../index.html"></a></h1>
  42         </td>
  43         <td>
  44       <div id="searchbox" style="display: none">
  45         <form class="search" action="../search.html" method="get">
  46           <input type="text" name="q" size="18" />
  47           <input type="submit" value="Search" />
  48           <input type="hidden" name="check_keywords" value="yes" />
  49           <input type="hidden" name="area" value="default" />
  50         </form>
  51       </div>
  52       <script type="text/javascript">$('#searchbox').show(0);</script>
  53         </td>
  54       </tr>
  55     </table>
  56     </div>
  57     <hr/>
  58     <div class="content">
  59     <div class="navbar" style="text-align:right;">
  60
  61
  62       <a class="prev" title="Basics" href="basics.html"><img src="../_static/prev.png" alt="prev"/></a>
  63       <a class="up" title="Design Guide" href="index.html"><img src="../_static/up.png" alt="up"/></a>
  64       <a class="next" title="Point" href="point.html"><img src="../_static/next.png" alt="next"/></a>
  65
  66     </div>
  67
  68   <div class="section" id="concepts">
  69 <h1>Concepts</h1>
  70 <p>All constructs in GIL are models of GIL concepts. A <em>concept</em> is a set of
  71 requirements that a type (or a set of related types) must fulfill to be used
  72 correctly in generic algorithms. The requirements include syntactic and
  73 algorithmic guarantees. For example, GIL class <code class="docutils literal"><span class="pre">pixel</span></code> is a model of GIL
  74 <code class="docutils literal"><span class="pre">PixelConcept</span></code>. The user may substitute the pixel class with one of their
  75 own, and, as long as it satisfies the requirements of <code class="docutils literal"><span class="pre">PixelConcept</span></code>,
  76 all other GIL classes and algorithms can be used with it.
  77 See more about concepts is avaialble at
  78 <a class="reference external" href="https://web.archive.org/web/20160324115943/http://www.generic-programming.org/languages/conceptcpp/">Generic Programming in ConceptC++</a></p>
  79 <p>In this document we will use a syntax for defining concepts that is described
  80 in the C++ standard proposal paper
  81 <a class="reference external" href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2006/n2081.pdf">[N2081] Concepts</a>.</p>
  82 <p>Here are some common concepts that will be used in GIL.
  83 Most of them are defined at the
  84 <a class="reference external" href="https://web.archive.org/web/20160326060858/http://www.generic-programming.org/languages/conceptcpp/concept_web.php">ConceptC++ Concept Web</a>:</p>
  85 <div class="highlight-cpp"><div class="highlight"><pre><span class="k">auto</span> <span class="n">concept</span> <span class="n">DefaultConstructible</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span>
  86 <span class="p">{</span>
  87     <span class="n">T</span><span class="o">::</span><span class="n">T</span><span class="p">();</span>
  88 <span class="p">};</span>
  89
  90 <span class="k">auto</span> <span class="n">concept</span> <span class="n">CopyConstructible</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span>
  91 <span class="p">{</span>
  92     <span class="n">T</span><span class="o">::</span><span class="n">T</span><span class="p">(</span><span class="n">T</span><span class="p">);</span>
  93     <span class="n">T</span><span class="o">::~</span><span class="n">T</span><span class="p">();</span>
  94 <span class="p">};</span>
  95
  96 <span class="k">auto</span> <span class="n">concept</span> <span class="n">Assignable</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="p">,</span> <span class="k">typename</span> <span class="n">U</span> <span class="o">=</span> <span class="n">T</span><span class="o">&gt;</span>
  97 <span class="p">{</span>
  98     <span class="k">typename</span> <span class="n">result_type</span><span class="p">;</span>
  99     <span class="n">result_type</span> <span class="k">operator</span><span class="o">=</span><span class="p">(</span><span class="n">T</span><span class="o">&amp;</span><span class="p">,</span> <span class="n">U</span><span class="p">);</span>
 100 <span class="p">};</span>
 101
 102 <span class="k">auto</span> <span class="n">concept</span> <span class="n">EqualityComparable</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="p">,</span> <span class="k">typename</span> <span class="n">U</span> <span class="o">=</span> <span class="n">T</span><span class="o">&gt;</span>
 103 <span class="p">{</span>
 104     <span class="kt">bool</span> <span class="k">operator</span><span class="o">==</span><span class="p">(</span><span class="n">T</span> <span class="n">x</span><span class="p">,</span> <span class="n">T</span> <span class="n">y</span><span class="p">);</span>
 105     <span class="kt">bool</span> <span class="k">operator</span><span class="o">!=</span><span class="p">(</span><span class="n">T</span> <span class="n">x</span><span class="p">,</span> <span class="n">T</span> <span class="n">y</span><span class="p">)</span> <span class="p">{</span> <span class="k">return</span> <span class="o">!</span><span class="p">(</span><span class="n">x</span><span class="o">==</span><span class="n">y</span><span class="p">);</span> <span class="p">}</span>
 106 <span class="p">};</span>
 107
 108 <span class="n">concept</span> <span class="n">SameType</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="p">,</span> <span class="k">typename</span> <span class="n">U</span><span class="o">&gt;</span> <span class="p">{</span> <span class="cm">/* unspecified */</span> <span class="p">};</span>
 109 <span class="k">template</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span> <span class="n">concept_map</span> <span class="n">SameType</span><span class="o">&lt;</span><span class="n">T</span><span class="p">,</span> <span class="n">T</span><span class="o">&gt;</span> <span class="p">{</span> <span class="cm">/* unspecified */</span> <span class="p">};</span>
 110
 111 <span class="k">auto</span> <span class="n">concept</span> <span class="n">Swappable</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span>
 112 <span class="p">{</span>
 113     <span class="kt">void</span> <span class="n">swap</span><span class="p">(</span><span class="n">T</span><span class="o">&amp;</span> <span class="n">t</span><span class="p">,</span> <span class="n">T</span><span class="o">&amp;</span> <span class="n">u</span><span class="p">);</span>
 114 <span class="p">};</span>
 115 </pre></div>
 116 </div>
 117 <p>Here are some additional basic concepts that GIL needs:</p>
 118 <div class="highlight-cpp"><div class="highlight"><pre><span class="k">auto</span> <span class="n">concept</span> <span class="n">Regular</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span> <span class="o">:</span>
 119     <span class="n">DefaultConstructible</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span><span class="p">,</span>
 120     <span class="n">CopyConstructible</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span><span class="p">,</span>
 121     <span class="n">EqualityComparable</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span><span class="p">,</span>
 122     <span class="n">Assignable</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span><span class="p">,</span>
 123     <span class="n">Swappable</span><span class="o">&lt;</span><span class="n">T</span><span class="o">&gt;</span>
 124 <span class="p">{};</span>
 125
 126 <span class="k">auto</span> <span class="n">concept</span> <span class="n">Metafunction</span><span class="o">&lt;</span><span class="k">typename</span> <span class="n">T</span><span class="o">&gt;</span>
 127 <span class="p">{</span>
 128     <span class="k">typename</span> <span class="n">type</span><span class="p">;</span>
 129 <span class="p">};</span>
 130 </pre></div>
 131 </div>
 132 </div>
 133
 134
 135     <div class="navbar" style="text-align:right;">
 136
 137
 138       <a class="prev" title="Basics" href="basics.html"><img src="../_static/prev.png" alt="prev"/></a>
 139       <a class="up" title="Design Guide" href="index.html"><img src="../_static/up.png" alt="up"/></a>
 140       <a class="next" title="Point" href="point.html"><img src="../_static/next.png" alt="next"/></a>
 141
 142     </div>
 143     </div>
 144     <div class="footer" role="contentinfo">
 145       Last updated on 2019-12-10 00:12:10.
 146       Created using <a href="http://sphinx-doc.org/">Sphinx</a> 1.5.6.
 147     </div>
 148   </body>
 149 </html>