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| <h2><span class="refentrytitle">Struct template domain</span></h2> |
| <p>boost::proto::domain — For use in defining domain tags to be used with <code class="computeroutput"> |
| <a class="link" href="extends.html" title="Struct template extends">proto::extends<></a></code>, |
| <code class="computeroutput"><a class="link" href="../../BOOST_PROTO_EXTENDS.html" title="Macro BOOST_PROTO_EXTENDS">BOOST_PROTO_EXTENDS</a>()</code> and |
| <code class="computeroutput"><a class="link" href="../../BOOST_PROTO_DEFINE_OPERATORS.html" title="Macro BOOST_PROTO_DEFINE_OPERATORS">BOOST_PROTO_DEFINE_OPERATORS</a>()</code>. |
| A <span class="emphasis"><em>domain</em></span> associates an expression type with a <span class="emphasis"><em>generator</em></span>, |
| and optionally a <span class="emphasis"><em>grammar</em></span>. It may also have a super-domain. Expressions |
| in a sub-domain are interoperable (i.e. can be combined freely with) expressions in a |
| super-domain. Finally, domains control how non-Proto objects are turned into Proto |
| expressions and how they are combined to form larger Proto expressions. |
| </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.domain_hpp" title="Header <boost/proto/domain.hpp>">boost/proto/domain.hpp</a>> |
| |
| </span><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> Generator <span class="special">=</span> <a class="link" href="default_generator.html" title="Struct default_generator">proto::default_generator</a><span class="special">,</span> |
| <span class="keyword">typename</span> Grammar <span class="special">=</span> <a class="link" href="_.html" title="Struct _">proto::_</a><span class="special">,</span> <span class="keyword">typename</span> Super <span class="special">=</span> <em class="replaceable"><code><span class="identifier">unspecified</span></code></em><span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="domain.html" title="Struct template domain">domain</a> <span class="special">:</span> <span class="keyword"></span> Generator <span class="special">{</span> |
| <span class="comment">// types</span> |
| <span class="keyword">typedef</span> <span class="identifier">Grammar</span> <a name="boost.proto.domain.proto_grammar"></a><span class="identifier">proto_grammar</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">Generator</span> <a name="boost.proto.domain.proto_generator"></a><span class="identifier">proto_generator</span><span class="special">;</span> |
| <span class="keyword">typedef</span> <span class="identifier">Super</span> <a name="boost.proto.domain.proto_super_domain"></a><span class="identifier">proto_super_domain</span><span class="special">;</span> |
| |
| <span class="comment">// member classes/structs/unions</span> |
| |
| <span class="comment">// A callable unary MonomorphicFunctionObject that specifies how objects are |
| // turned into Proto expressions in this domain. The resulting expression |
| // object is suitable for storage in a local variable.</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="domain/as_expr.html" title="Struct template as_expr">as_expr</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="callable.html" title="Struct callable">proto::callable</a> <span class="special">{</span> |
| <span class="comment">// types</span> |
| <span class="keyword">typedef</span> <em class="replaceable"><code><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></code></em> <a class="link" href="domain/as_expr.html#boost.proto.domain.as_expr.result_type"><span class="identifier">result_type</span></a><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="domain/as_expr.html#id1258448-bb">public member functions</a></span> |
| <span class="identifier">result_type</span> <a class="link" href="domain/as_expr.html#id1258452-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">T</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> |
| <span class="special">}</span><span class="special">;</span> |
| |
| <span class="comment">// A callable unary MonomorphicFunctionObject that specifies how objects are |
| // turned into Proto expressions in this domain, for use in scenarios where |
| // the resulting expression is intended to be made a child of another |
| // expression.</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> |
| <span class="keyword">struct</span> <a class="link" href="domain/as_child.html" title="Struct template as_child">as_child</a> <span class="special">:</span> <span class="keyword"></span> <a class="link" href="callable.html" title="Struct callable">proto::callable</a> <span class="special">{</span> |
| <span class="comment">// types</span> |
| <span class="keyword">typedef</span> <em class="replaceable"><code><span class="identifier">see</span><span class="special">-</span><span class="identifier">below</span></code></em> <a class="link" href="domain/as_child.html#boost.proto.domain.as_child.result_type"><span class="identifier">result_type</span></a><span class="special">;</span> |
| |
| <span class="comment">// <a class="link" href="domain/as_child.html#id1258612-bb">public member functions</a></span> |
| <span class="identifier">result_type</span> <a class="link" href="domain/as_child.html#id1258617-bb"><span class="keyword">operator</span><span class="special">(</span><span class="special">)</span></a><span class="special">(</span><span class="identifier">T</span> <span class="special">&</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span> |
| <span class="special">}</span><span class="special">;</span> |
| <span class="special">}</span><span class="special">;</span></pre></div> |
| <div class="refsect1"> |
| <a name="id2274591"></a><h2>Description</h2> |
| <p> |
| The Generator parameter determines how new expressions in the domain are post-processed. Typically, a generator |
| wraps all new expressions in a wrapper that imparts domain-specific behaviors to expressions within |
| its domain. (See <code class="computeroutput"><a class="link" href="extends.html" title="Struct template extends">proto::extends<></a></code>.) |
| </p> |
| <p> |
| The Grammar parameter determines whether a given expression is valid within the domain, and automatically |
| disables any operator overloads which would cause an invalid expression to be created. By default, |
| the Grammar parameter defaults to the wildcard, <code class="computeroutput"><a class="link" href="_.html" title="Struct _">proto::_</a> |
| </code>, which makes all expressions valid within the domain. |
| </p> |
| <p> |
| The Super parameter declares the domain currently being defined to be a sub-domain of Super. An expression in |
| a sub-domain can be freely combined with expressions in its super-domain (and <span class="emphasis"><em>its</em></span> |
| super-domain, etc.). |
| </p> |
| <p> |
| Example: </p> |
| <pre class="programlisting"> <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Expr</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">MyExpr</span><span class="special">;</span> |
| |
| <span class="keyword">struct</span> <span class="identifier">MyGrammar</span> |
| <span class="special">:</span> <a class="link" href="or_.html" title="Struct template or_">proto::or_</a><span class="special"><</span> <a class="link" href="terminal.html" title="Struct template terminal">proto::terminal</a><span class="special"><</span><span class="identifier">_</span><span class="special">></span><span class="special">,</span> <a class="link" href="plus.html" title="Struct template plus">proto::plus</a><span class="special"><</span><span class="identifier">MyGrammar</span><span class="special">,</span> <span class="identifier">MyGrammar</span><span class="special">></span> <span class="special">></span> |
| <span class="special">{</span><span class="special">}</span><span class="special">;</span> |
| |
| <span class="comment">// Define MyDomain, in which all expressions are</span> |
| <span class="comment">// wrapped in MyExpr<> and only expressions that</span> |
| <span class="comment">// conform to MyGrammar are allowed.</span> |
| <span class="keyword">struct</span> <span class="identifier">MyDomain</span> |
| <span class="special">:</span> <a class="link" href="domain.html" title="Struct template domain">proto::domain</a><span class="special"><</span><a class="link" href="generator.html" title="Struct template generator">proto::generator</a><span class="special"><</span><span class="identifier">MyExpr</span><span class="special">></span><span class="special">,</span> <span class="identifier">MyGrammar</span><span class="special">></span> |
| <span class="special">{</span><span class="special">}</span><span class="special">;</span> |
| |
| <span class="comment">// Use MyDomain to define MyExpr</span> |
| <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Expr</span><span class="special">></span> |
| <span class="keyword">struct</span> <span class="identifier">MyExpr</span> |
| <span class="special">:</span> <a class="link" href="extends.html" title="Struct template extends">proto::extends</a><span class="special"><</span><span class="identifier">Expr</span><span class="special">,</span> <span class="identifier">MyExpr</span><span class="special"><</span><span class="identifier">Expr</span><span class="special">></span><span class="special">,</span> <span class="identifier">MyDomain</span><span class="special">></span> |
| <span class="special">{</span> |
| <span class="comment">// ...</span> |
| <span class="special">}</span><span class="special">;</span> |
| </pre> |
| <p> |
| </p> |
| <p> |
| The <code class="computeroutput"><a class="link" href="domain/as_expr.html" title="Struct template as_expr">domain::as_expr</a><></code> and |
| <code class="computeroutput"><a class="link" href="domain/as_child.html" title="Struct template as_child">domain::as_child</a><></code> member |
| templates define how non-Proto objects are turned into Proto terminals and how Proto |
| expressions should be processed before they are combined to form larger expressions. |
| They can be overridden in a derived domain for customization. See their descriptions to |
| understand how Proto uses these two templates and what their default behavior is. |
| </p> |
| </div> |
| </div> |
| <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> |
| <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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