ceph/src/boost/libs/mpl/doc/refmanual/or.html

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   7 <title>The MPL Reference Manual: or_</title>
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  11 <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./and.html" class="navigation-link">Prev</a>&nbsp;<a href="./not.html" class="navigation-link">Next</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./and.html" class="navigation-link">Back</a>&nbsp;<a href="./not.html" class="navigation-link">Along</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./logical-operations.html" class="navigation-link">Up</a>&nbsp;<a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator">&nbsp;|&nbsp;</span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td>
  12 <td class="header-group page-location"><a href="../refmanual.html" class="navigation-link">Front Page</a> / <a href="./metafunctions.html" class="navigation-link">Metafunctions</a> / <a href="./logical-operations.html" class="navigation-link">Logical Operations</a> / <a href="./or.html" class="navigation-link">or_</a></td>
  13 </tr></table><div class="header-separator"></div>
  14 <div class="section" id="or">
  15 <h1><a class="toc-backref" href="./logical-operations.html#id1551">or_</a></h1>
  16 <div class="section" id="id1075">
  17 <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3>
  18 <pre class="literal-block">
  19 template&lt;
  20       typename F1
  21     , typename F2
  22     <em>...</em>
  23     , typename F<em>n</em> = <em>unspecified</em>
  24     &gt;
  25 struct <a href="./or.html" class="identifier">or_</a>
  26 {
  27     typedef <em>unspecified</em> type;
  28 };
  29 </pre>
  30 </div>
  31 <div class="section" id="id1076">
  32 <h3><a class="subsection-title" href="#description" name="description">Description</a></h3>
  33 <p>Returns the result of short-circuit <em>logical or</em> (<tt class="literal"><span class="pre">||</span></tt>) operation on its arguments.</p>
  34 </div>
  35 <div class="section" id="id1077">
  36 <h3><a class="subsection-title" href="#header" name="header">Header</a></h3>
  37 <pre class="literal-block">
  38 #include &lt;<a href="../../../../boost/mpl/or.hpp" class="header">boost/mpl/or.hpp</a>&gt;
  39 #include &lt;<a href="../../../../boost/mpl/logical.hpp" class="header">boost/mpl/logical.hpp</a>&gt;
  40 </pre>
  41 </div>
  42 <div class="section" id="id1078">
  43 <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3>
  44 <table border="1" class="docutils table">
  45 <colgroup>
  46 <col width="17%" />
  47 <col width="30%" />
  48 <col width="53%" />
  49 </colgroup>
  50 <thead valign="bottom">
  51 <tr><th class="head">Parameter</th>
  52 <th class="head">Requirement</th>
  53 <th class="head">Description</th>
  54 </tr>
  55 </thead>
  56 <tbody valign="top">
  57 <tr><td><tt class="literal"><span class="pre">F1</span></tt>, <tt class="literal"><span class="pre">F2</span></tt>,... <tt class="literal"><span class="pre">Fn</span></tt></td>
  58 <td>Nullary <a class="reference internal" href="./metafunction.html">Metafunction</a></td>
  59 <td>Operation's arguments.</td>
  60 </tr>
  61 </tbody>
  62 </table>
  63 </div>
  64 <div class="section" id="id1079">
  65 <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3>
  66 <p>For arbitrary nullary <a class="reference internal" href="./metafunction.html">Metafunction</a>s <tt class="literal"><span class="pre">f1</span></tt>, <tt class="literal"><span class="pre">f2</span></tt>,... <tt class="literal"><span class="pre">fn</span></tt>:</p>
  67 <pre class="literal-block">
  68 typedef <a href="./or.html" class="identifier">or_</a>&lt;f1,f2,<em>...</em>,f<em>n</em>&gt;::type r;
  69 </pre>
  70 <table class="docutils field-list" frame="void" rules="none">
  71 <col class="field-name" />
  72 <col class="field-body" />
  73 <tbody valign="top">
  74 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><a class="reference internal" href="./integral-constant.html">Integral Constant</a>.</td>
  75 </tr>
  76 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><tt class="literal"><span class="pre">r</span></tt> is <tt class="literal"><span class="pre"><a href="./bool.html" class="identifier">true_</a></span></tt> if either of <tt class="literal"><span class="pre">f1::type::value</span></tt>, <tt class="literal"><span class="pre">f2::type::value</span></tt>,...
  77 <tt class="literal"><span class="pre">fn::type::value</span></tt> expressions evaluates to <tt class="literal"><span class="pre">true</span></tt>, and <tt class="literal"><span class="pre"><a href="./bool.html" class="identifier">false_</a></span></tt> otherwise;
  78 guarantees left-to-right evaluation; the operands subsequent to the first
  79 <tt class="literal"><span class="pre">f</span></tt><em>i</em> metafunction that evaluates to <tt class="literal"><span class="pre">true</span></tt> are not evaluated.</td>
  80 </tr>
  81 </tbody>
  82 </table>
  83 <!-- .......................................................................... -->
  84 <pre class="literal-block">
  85 typedef <a href="./or.html" class="identifier">or_</a>&lt;f1,f2,<em>...</em>,f<em>n</em>&gt; r;
  86 </pre>
  87 <table class="docutils field-list" frame="void" rules="none">
  88 <col class="field-name" />
  89 <col class="field-body" />
  90 <tbody valign="top">
  91 <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./integral-constant.html">Integral Constant</a>.</p>
  92 </td>
  93 </tr>
  94 <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">Equivalent to</p>
  95 <pre class="last literal-block">
  96 struct r : <a href="./or.html" class="identifier">or_</a>&lt;f1,f2,<em>...</em>,f<em>n</em>&gt;::type {};
  97 </pre>
  98 </td>
  99 </tr>
 100 </tbody>
 101 </table>
 102 </div>
 103 <div class="section" id="id1080">
 104 <h3><a class="subsection-title" href="#example" name="example">Example</a></h3>
 105 <pre class="literal-block">
 106 struct unknown;
 107
 108 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./or.html" class="identifier">or_</a>&lt; <a href="./bool.html" class="identifier">true_</a>,<a href="./bool.html" class="identifier">true_</a> &gt; ));
 109 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./or.html" class="identifier">or_</a>&lt; <a href="./bool.html" class="identifier">false_</a>,<a href="./bool.html" class="identifier">true_</a> &gt; ));
 110 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./or.html" class="identifier">or_</a>&lt; <a href="./bool.html" class="identifier">true_</a>,<a href="./bool.html" class="identifier">false_</a> &gt; ));
 111 <a href="./assert-not.html" class="identifier">BOOST_MPL_ASSERT_NOT</a>(( <a href="./or.html" class="identifier">or_</a>&lt; <a href="./bool.html" class="identifier">false_</a>,<a href="./bool.html" class="identifier">false_</a> &gt; ));
 112 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./or.html" class="identifier">or_</a>&lt; <a href="./bool.html" class="identifier">true_</a>,unknown &gt; )); // OK
 113 <a href="./assert.html" class="identifier">BOOST_MPL_ASSERT</a>(( <a href="./or.html" class="identifier">or_</a>&lt; <a href="./bool.html" class="identifier">true_</a>,unknown,unknown &gt; )); // OK too
 114 </pre>
 115 </div>
 116 <div class="section" id="id1081">
 117 <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3>
 118 <p><a class="reference internal" href="./metafunctions.html">Metafunctions</a>, <a class="reference internal" href="./logical-operations.html">Logical Operations</a>, <a class="reference internal" href="./and.html">and_</a>, <a class="reference internal" href="./not.html">not_</a></p>
 119 <!-- Metafunctions/Logical Operations//not_ |30 -->
 120 </div>
 121 </div>
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 125 <td><div class="copyright-footer"><div class="copyright">Copyright ©  2001-2009 Aleksey Gurtovoy and David Abrahams</div>
 126 Distributed under the Boost Software License, Version 1.0. (See accompanying
 127 file LICENSE_1_0.txt or copy at <a class="reference external" href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)</div></td></tr></table></body>
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