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| <a name="boost.proto.matches"></a><div class="titlepage"></div> |
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| <h2><span class="refentrytitle">Struct template matches</span></h2> |
| <p>boost::proto::matches — A Boolean metafunction that evaluates whether a given expression type matches a grammar.</p> |
| </div> |
| <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> |
| <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../proto/reference.html#header.boost.proto.matches_hpp" title="Header <boost/proto/matches.hpp>">boost/proto/matches.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <a class="link" href="../../Expr.html" title="Concept Expr">Expr</a><span class="special">,</span> <span class="keyword">typename</span> Grammar<span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="matches.html" title="Struct template matches">matches</a> <span class="special">:</span> <span class="keyword"></span> mpl::bool_<<em class="replaceable"><code>true-or-false</code></em>> <span class="special">{</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2333127"></a><h2>Description</h2> |
| <p> |
| <code class="computeroutput">proto::matches<Expr, Grammar></code> inherits from |
| <code class="computeroutput">mpl::true_</code> if |
| <code class="computeroutput">Expr::proto_grammar</code> matches |
| <code class="computeroutput">Grammar::proto_grammar</code>, and from |
| <code class="computeroutput">mpl::false_</code> otherwise. |
| </p> |
| <p> |
| Non-terminal expressions are matched against a grammar according to the following rules: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"><p> |
| The wildcard pattern, <code class="computeroutput"> |
| <a class="link" href="_.html" title="Struct _">proto::_</a> |
| </code>, matches any expression. |
| </p></li> |
| <li class="listitem"><p> |
| An expression |
| <code class="computeroutput"> |
| <a class="link" href="basic_expr.html" title="Struct template basic_expr">proto::basic_expr</a><AT, |
| <a class="link" href="listN.html" title="Struct template listN"> |
| proto::listN |
| </a><A<sub>0</sub>,...A<sub>n</sub>> |
| > |
| </code> |
| matches a grammar |
| <code class="computeroutput"> |
| <a class="link" href="basic_expr.html" title="Struct template basic_expr">proto::basic_expr</a><BT, |
| <a class="link" href="listN.html" title="Struct template listN"> |
| proto::listN |
| </a><B<sub>0</sub>,...B<sub>n</sub>> |
| > |
| </code> if |
| <code class="computeroutput">BT</code> is <code class="computeroutput"> |
| <a class="link" href="_.html" title="Struct _">proto::_</a> |
| </code> or |
| <code class="computeroutput">AT</code>, and if <code class="computeroutput"> |
| A<sub>x</sub> |
| </code> matches |
| <code class="computeroutput"> |
| B<sub>x</sub> |
| </code> for each <code class="computeroutput">x</code> in <code class="computeroutput">[0,n]</code>. |
| </p></li> |
| <li class="listitem"><p> |
| An expression |
| <code class="computeroutput"> |
| <a class="link" href="basic_expr.html" title="Struct template basic_expr">proto::basic_expr</a><AT, |
| <a class="link" href="listN.html" title="Struct template listN"> |
| proto::listN |
| </a><A<sub>0</sub>,...A<sub>n</sub>,U<sub>0</sub>,...U<sub>m</sub>> |
| > |
| </code> matches a grammar |
| <code class="computeroutput"> |
| <a class="link" href="basic_expr.html" title="Struct template basic_expr">proto::basic_expr</a><BT, |
| <a class="link" href="listN.html" title="Struct template listN"> |
| proto::listM |
| </a><B<sub>0</sub>,...B<sub>n</sub>,<a class="link" href="vararg.html" title="Struct template vararg">proto::vararg</a><V> |
| > > |
| </code> if |
| <code class="computeroutput">BT</code> is <code class="computeroutput"> |
| <a class="link" href="_.html" title="Struct _">proto::_</a> |
| </code> or |
| <code class="computeroutput">AT</code>, and if |
| <code class="computeroutput"> |
| A<sub>x</sub> |
| </code> matches |
| <code class="computeroutput"> |
| B<sub>x</sub> |
| </code> for each |
| <code class="computeroutput">x</code> in <code class="computeroutput">[0,n]</code> and if |
| <code class="computeroutput"> |
| U<sub>x</sub> |
| </code> matches |
| <code class="computeroutput">V</code> for each <code class="computeroutput">x</code> in |
| <code class="computeroutput">[0,m]</code>. |
| </p></li> |
| <li class="listitem"><p> |
| An expression <code class="computeroutput">E</code> matches |
| <code class="computeroutput"> |
| <a class="link" href="or_.html" title="Struct template or_">proto::or_</a><B<sub>0</sub>,...B<sub>n</sub>> |
| </code> if |
| <code class="computeroutput">E</code> matches some |
| <code class="computeroutput"> |
| B<sub>x</sub> |
| </code> for |
| <code class="computeroutput">x</code> in <code class="computeroutput">[0,n]</code>. |
| </p></li> |
| <li class="listitem"><p> |
| An expression <code class="computeroutput">E</code> matches |
| <code class="computeroutput"> |
| <a class="link" href="and_.html" title="Struct template and_">proto::and_</a><B<sub>0</sub>,...B<sub>n</sub>> |
| </code> if |
| <code class="computeroutput">E</code> matches all |
| <code class="computeroutput"> |
| B<sub>x</sub> |
| </code> for |
| <code class="computeroutput">x</code> in <code class="computeroutput">[0,n]</code>. |
| </p></li> |
| <li class="listitem"> |
| <p> |
| An expression <code class="computeroutput">E</code> matches |
| <code class="computeroutput"> |
| <a class="link" href="if_.html" title="Struct template if_">proto::if_</a><T,U,V> |
| </code> if: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="circle"> |
| <li class="listitem"> |
| <code class="computeroutput"> |
| boost::result_of<<a class="link" href="when.html" title="Struct template when">proto::when</a><<a class="link" href="_.html" title="Struct _">proto::_</a>,T>(E)>::type::value |
| </code> |
| is <code class="computeroutput">true</code> and |
| <code class="computeroutput">E</code> matches |
| <code class="computeroutput">U</code>, <span class="emphasis"><em>or</em></span> |
| </li> |
| <li class="listitem"> |
| <code class="computeroutput"> |
| boost::result_of<<a class="link" href="when.html" title="Struct template when">proto::when</a><<a class="link" href="_.html" title="Struct _">proto::_</a>,T>(E)>::type::value |
| </code> |
| is <code class="computeroutput">false</code> and <code class="computeroutput">E</code> matches |
| <code class="computeroutput">V</code>. |
| </li> |
| </ul></div> |
| <p> |
| Note: <code class="computeroutput">U</code> defaults to <code class="computeroutput"> |
| <a class="link" href="_.html" title="Struct _">proto::_</a> |
| </code> |
| and <code class="computeroutput">V</code> defaults to |
| <code class="computeroutput"> |
| <a class="link" href="not_.html" title="Struct template not_">proto::not_</a><<a class="link" href="_.html" title="Struct _">proto::_</a>> |
| </code>. |
| </p> |
| </li> |
| <li class="listitem"><p> |
| An expression <code class="computeroutput">E</code> matches |
| <code class="computeroutput"> |
| <a class="link" href="not_.html" title="Struct template not_">proto::not_</a><T> |
| </code> if |
| <code class="computeroutput">E</code> does <span class="emphasis"><em>not</em></span> match <code class="computeroutput">T</code>. |
| </p></li> |
| <li class="listitem"><p> |
| An expression <code class="computeroutput">E</code> matches |
| <code class="computeroutput"> |
| <a class="link" href="switch_.html" title="Struct template switch_">proto::switch_</a><C> |
| </code> if |
| <code class="computeroutput">E</code> matches <code class="computeroutput">C::case_<E::proto_tag></code>. |
| </p></li> |
| </ul></div> |
| <p> |
| </p> |
| <p> |
| A terminal expression |
| <code class="computeroutput"> |
| <a class="link" href="basic_expr.html" title="Struct template basic_expr">proto::basic_expr</a><AT, |
| <a class="link" href="term.html" title="Struct template term">proto::term</a><A> > |
| </code> matches a grammar |
| <code class="computeroutput"> |
| <a class="link" href="basic_expr.html" title="Struct template basic_expr">proto::basic_expr</a><BT, <a class="link" href="term.html" title="Struct template term">proto::term</a><B> > |
| </code> |
| if <code class="computeroutput">BT</code> is <code class="computeroutput"><a class="link" href="_.html" title="Struct _">proto::_</a></code> |
| or <code class="computeroutput">AT</code> and one of the following is true: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"><p> |
| <code class="computeroutput">B</code> is the wildcard pattern, |
| <code class="computeroutput"> |
| <a class="link" href="_.html" title="Struct _">proto::_</a> |
| </code> |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">A</code> is <code class="computeroutput">B</code> |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">A</code> is <code class="computeroutput">B &</code> |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">A</code> is <code class="computeroutput">B const &</code> |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">B</code> is <code class="computeroutput"> |
| <a class="link" href="exact.html" title="Struct template exact">proto::exact</a><A> |
| </code> |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">B</code> is |
| <code class="computeroutput"> |
| <a class="link" href="convertible_to.html" title="Struct template convertible_to">proto::convertible_to</a><X> |
| </code> |
| and <code class="computeroutput">boost::is_convertible<A,X>::value</code> is |
| <code class="computeroutput">true</code>. |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">A</code> is <code class="computeroutput">X[M]</code> or |
| <code class="computeroutput">X(&)[M]</code> and |
| <code class="computeroutput">B</code> is <code class="computeroutput"> |
| X[<a class="link" href="N.html" title="Global N">proto::N</a>] |
| </code>. |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">A</code> is <code class="computeroutput">X(&)[M]</code> |
| and <code class="computeroutput">B</code> is <code class="computeroutput"> |
| X(&)[<a class="link" href="N.html" title="Global N">proto::N</a>] |
| </code>. |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">A</code> is <code class="computeroutput">X[M]</code> or |
| <code class="computeroutput">X(&)[M]</code> and <code class="computeroutput">B</code> is |
| <code class="computeroutput">X*</code>. |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">B</code> <em class="replaceable"><code>lambda-matches</code></em> |
| <code class="computeroutput">A</code> (see below). |
| </p></li> |
| </ul></div> |
| <p> |
| </p> |
| <p> |
| A type <code class="computeroutput">B</code> <em class="replaceable"><code>lambda-matches</code></em> |
| <code class="computeroutput">A</code> if one of the following is true: |
| </p> |
| <div class="itemizedlist"><ul class="itemizedlist" type="disc"> |
| <li class="listitem"><p> |
| <code class="computeroutput">B</code> is <code class="computeroutput">A</code> |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">B</code> is the wildcard pattern, <code class="computeroutput"> |
| <a class="link" href="_.html" title="Struct _">proto::_</a> |
| </code> |
| </p></li> |
| <li class="listitem"><p> |
| <code class="computeroutput">B</code> is <code class="computeroutput"> |
| T<B<sub>0</sub>,...B<sub>n</sub>> |
| </code> and <code class="computeroutput">A</code> is <code class="computeroutput"> |
| T<A<sub>0</sub>,...A<sub>n</sub>> |
| </code> and for each <code class="computeroutput">x</code> in <code class="computeroutput">[0,n]</code>, |
| <code class="computeroutput">A<sub>x</sub></code> and |
| <code class="computeroutput">B<sub>x</sub></code> are types such that |
| <code class="computeroutput">A<sub>x</sub></code> <em class="replaceable"><code>lambda-matches</code></em> |
| <code class="computeroutput">B<sub>x</sub></code> |
| </p></li> |
| </ul></div> |
| <p> |
| </p> |
| </div> |
| </div> |
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| <td align="left"></td> |
| <td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p> |
| Distributed under the Boost Software License, Version 1.0. (See accompanying |
| file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) |
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