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1 | <?xml version="1.0" encoding="utf-8" ?> |
| 2 | <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> | |
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| 4 | <head> | |
| 5 | <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> | |
| 6 | <meta name="generator" content="Docutils 0.7: http://docutils.sourceforge.net/" /> | |
| 7 | <title>The MPL Reference Manual: lambda</title> | |
| 8 | <link rel="stylesheet" href="../style.css" type="text/css" /> | |
| 9 | </head> | |
| 10 | <body class="docframe refmanual"> | |
| 11 | <table class="header"><tr class="header"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./placeholders.html" class="navigation-link">Prev</a> <a href="./bind.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./placeholders.html" class="navigation-link">Back</a> <a href="./bind.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./composition-and-argument-binding.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </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="./composition-and-argument-binding.html" class="navigation-link">Composition and Argument Binding</a> / <a href="./lambda.html" class="navigation-link">lambda</a></td> | |
| 13 | </tr></table><div class="header-separator"></div> | |
| 14 | <div class="section" id="lambda"> | |
| 15 | <h1><a class="toc-backref" href="./composition-and-argument-binding.html#id1530">lambda</a></h1> | |
| 16 | <div class="section" id="id922"> | |
| 17 | <h3><a class="subsection-title" href="#synopsis" name="synopsis">Synopsis</a></h3> | |
| 18 | <pre class="literal-block"> | |
| 19 | template< | |
| 20 | typename X | |
| 21 | , typename Tag = <em>unspecified</em> | |
| 22 | > | |
| 23 | struct <a href="./lambda.html" class="identifier">lambda</a> | |
| 24 | { | |
| 25 | typedef <em>unspecified</em> type; | |
| 26 | }; | |
| 27 | </pre> | |
| 28 | </div> | |
| 29 | <div class="section" id="id923"> | |
| 30 | <h3><a class="subsection-title" href="#description" name="description">Description</a></h3> | |
| 31 | <p>If <tt class="literal"><span class="pre">X</span></tt> is a <a class="reference internal" href="./placeholder-expression.html">Placeholder Expression</a>, transforms <tt class="literal"><span class="pre">X</span></tt> into a corresponding | |
| 32 | <a class="reference internal" href="./metafunction-class.html">Metafunction Class</a>, otherwise <tt class="literal"><span class="pre">X</span></tt> is returned unchanged.</p> | |
| 33 | </div> | |
| 34 | <div class="section" id="id924"> | |
| 35 | <h3><a class="subsection-title" href="#header" name="header">Header</a></h3> | |
| 36 | <pre class="literal-block"> | |
| 37 | #include <<a href="../../../../boost/mpl/lambda.hpp" class="header">boost/mpl/lambda.hpp</a>> | |
| 38 | </pre> | |
| 39 | </div> | |
| 40 | <div class="section" id="id925"> | |
| 41 | <h3><a class="subsection-title" href="#parameters" name="parameters">Parameters</a></h3> | |
| 42 | <table border="1" class="docutils table"> | |
| 43 | <colgroup> | |
| 44 | <col width="18%" /> | |
| 45 | <col width="27%" /> | |
| 46 | <col width="55%" /> | |
| 47 | </colgroup> | |
| 48 | <thead valign="bottom"> | |
| 49 | <tr><th class="head">Parameter</th> | |
| 50 | <th class="head">Requirement</th> | |
| 51 | <th class="head">Description</th> | |
| 52 | </tr> | |
| 53 | </thead> | |
| 54 | <tbody valign="top"> | |
| 55 | <tr><td><tt class="literal"><span class="pre">X</span></tt></td> | |
| 56 | <td>Any type</td> | |
| 57 | <td>An expression to transform.</td> | |
| 58 | </tr> | |
| 59 | <tr><td><tt class="literal"><span class="pre">Tag</span></tt></td> | |
| 60 | <td>Any type</td> | |
| 61 | <td>A tag determining transform semantics.</td> | |
| 62 | </tr> | |
| 63 | </tbody> | |
| 64 | </table> | |
| 65 | </div> | |
| 66 | <div class="section" id="id926"> | |
| 67 | <h3><a class="subsection-title" href="#expression-semantics" name="expression-semantics">Expression semantics</a></h3> | |
| 68 | <p>For arbitrary types <tt class="literal"><span class="pre">x</span></tt> and <tt class="literal"><span class="pre">tag</span></tt>:</p> | |
| 69 | <pre class="literal-block"> | |
| 70 | typedef <a href="./lambda.html" class="identifier">lambda</a><x>::type f; | |
| 71 | </pre> | |
| 72 | <table class="docutils field-list" frame="void" rules="none"> | |
| 73 | <col class="field-name" /> | |
| 74 | <col class="field-body" /> | |
| 75 | <tbody valign="top"> | |
| 76 | <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./metafunction-class.html">Metafunction Class</a>.</p> | |
| 77 | </td> | |
| 78 | </tr> | |
| 79 | <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">If <tt class="literal"><span class="pre">x</span></tt> is a <a class="reference internal" href="./placeholder-expression.html">Placeholder Expression</a> in a general form <tt class="literal"><span class="pre">X<a1,...an></span></tt>, where | |
| 80 | <tt class="literal"><span class="pre">X</span></tt> is a class template and <tt class="literal"><span class="pre">a1</span></tt>,... <tt class="literal"><span class="pre">an</span></tt> are arbitrary types, equivalent | |
| 81 | to</p> | |
| 82 | <pre class="literal-block"> | |
| 83 | typedef <a href="./protect.html" class="identifier">protect</a>< <a href="./bind.html" class="identifier">bind</a>< | |
| 84 | <a href="./quote.html" class="identifier">quote</a><em>n</em><X> | |
| 85 | , <a href="./lambda.html" class="identifier">lambda</a><a1>::type,<em>...</em> <a href="./lambda.html" class="identifier">lambda</a><a<em>n</em>>::type | |
| 86 | > > f; | |
| 87 | </pre> | |
| 88 | <p class="last">otherwise, <tt class="literal"><span class="pre">f</span></tt> is identical to <tt class="literal"><span class="pre">x</span></tt>.</p> | |
| 89 | </td> | |
| 90 | </tr> | |
| 91 | </tbody> | |
| 92 | </table> | |
| 93 | <!-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --> | |
| 94 | <pre class="literal-block"> | |
| 95 | typedef <a href="./lambda.html" class="identifier">lambda</a><x,tag>::type f; | |
| 96 | </pre> | |
| 97 | <table class="docutils field-list" frame="void" rules="none"> | |
| 98 | <col class="field-name" /> | |
| 99 | <col class="field-body" /> | |
| 100 | <tbody valign="top"> | |
| 101 | <tr class="field"><th class="field-name">Return type:</th><td class="field-body"><p class="first"><a class="reference internal" href="./metafunction-class.html">Metafunction Class</a>.</p> | |
| 102 | </td> | |
| 103 | </tr> | |
| 104 | <tr class="field"><th class="field-name">Semantics:</th><td class="field-body"><p class="first">If <tt class="literal"><span class="pre">x</span></tt> is a <a class="reference internal" href="./placeholder-expression.html">Placeholder Expression</a> in a general form <tt class="literal"><span class="pre">X<a1,...an></span></tt>, where | |
| 105 | <tt class="literal"><span class="pre">X</span></tt> is a class template and <tt class="literal"><span class="pre">a1</span></tt>,... <tt class="literal"><span class="pre">an</span></tt> are arbitrary types, equivalent | |
| 106 | to</p> | |
| 107 | <pre class="literal-block"> | |
| 108 | typedef <a href="./protect.html" class="identifier">protect</a>< <a href="./bind.html" class="identifier">bind</a>< | |
| 109 | <a href="./quote.html" class="identifier">quote</a><em>n</em><X,tag> | |
| 110 | , <a href="./lambda.html" class="identifier">lambda</a><a1,tag>::type,<em>...</em> <a href="./lambda.html" class="identifier">lambda</a><a<em>n</em>,tag>::type | |
| 111 | > > f; | |
| 112 | </pre> | |
| 113 | <p class="last">otherwise, <tt class="literal"><span class="pre">f</span></tt> is identical to <tt class="literal"><span class="pre">x</span></tt>.</p> | |
| 114 | </td> | |
| 115 | </tr> | |
| 116 | </tbody> | |
| 117 | </table> | |
| 118 | </div> | |
| 119 | <div class="section" id="id927"> | |
| 120 | <h3><a class="subsection-title" href="#example" name="example">Example</a></h3> | |
| 121 | <pre class="literal-block"> | |
| 122 | template< typename N1, typename N2 > struct int_plus | |
| 123 | : <a href="./int.html" class="identifier">int_</a><( N1::value + N2::value )> | |
| 124 | { | |
| 125 | }; | |
| 126 | ||
| 127 | typedef <a href="./lambda.html" class="identifier">lambda</a>< int_plus<<a href="./placeholders.html" class="identifier">_1</a>, <a href="./int.html" class="identifier">int_</a><42> > >::type f1; | |
| 128 | typedef <a href="./bind.html" class="identifier">bind</a>< <a href="./quote.html" class="identifier">quote</a><tt class="literal"><span class="pre">2</span></tt><int_plus>, <a href="./placeholders.html" class="identifier">_1</a>, <a href="./int.html" class="identifier">int_</a><42> > f2; | |
| 129 | ||
| 130 | typedef f1::<a href="./apply.html" class="identifier">apply</a><42>::type r1; | |
| 131 | typedef f2::<a href="./apply.html" class="identifier">apply</a><42>::type r2; | |
| 132 | ||
| 133 | <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( r1::value, ==, 84 ); | |
| 134 | <a href="./assert-relation.html" class="identifier">BOOST_MPL_ASSERT_RELATION</a>( r2::value, ==, 84 ); | |
| 135 | </pre> | |
| 136 | </div> | |
| 137 | <div class="section" id="id928"> | |
| 138 | <h3><a class="subsection-title" href="#see-also" name="see-also">See also</a></h3> | |
| 139 | <p><a class="reference internal" href="./composition-and-argument-binding.html">Composition and Argument Binding</a>, <a class="reference internal" href="./invocation.html">invocation</a>, <a class="reference internal" href="./placeholders.html">Placeholders</a>, <a class="reference internal" href="./bind.html">bind</a>, <a class="reference internal" href="./quote.html">quote</a>, <a class="reference internal" href="./protect.html">protect</a>, <a class="reference internal" href="./apply.html">apply</a></p> | |
| 140 | <!-- Metafunctions/Composition and Argument Binding//bind |30 --> | |
| 141 | </div> | |
| 142 | </div> | |
| 143 | ||
| 144 | <div class="footer-separator"></div> | |
| 145 | <table class="footer"><tr class="footer"><td class="header-group navigation-bar"><span class="navigation-group"><a href="./placeholders.html" class="navigation-link">Prev</a> <a href="./bind.html" class="navigation-link">Next</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./placeholders.html" class="navigation-link">Back</a> <a href="./bind.html" class="navigation-link">Along</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./composition-and-argument-binding.html" class="navigation-link">Up</a> <a href="../refmanual.html" class="navigation-link">Home</a></span><span class="navigation-group-separator"> | </span><span class="navigation-group"><a href="./refmanual_toc.html" class="navigation-link">Full TOC</a></span></td> | |
| 146 | <td><div class="copyright-footer"><div class="copyright">Copyright © 2001-2009 Aleksey Gurtovoy and David Abrahams</div> | |
| 147 | Distributed under the Boost Software License, Version 1.0. (See accompanying | |
| 148 | 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> | |
| 149 | </html> |