124 lines
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124 lines
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<a accesskey="p" href="Expr.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="proto/reference.html"><img src="../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="PolymorphicFunctionObject.html"><img src="../../doc/src/images/next.png" alt="Next"></a>
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<div class="refentry">
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<a name="ObjectTransform"></a><div class="titlepage"></div>
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<div class="refnamediv">
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<h2><span class="refentrytitle">Concept ObjectTransform</span></h2>
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<p>ObjectTransform</p>
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</div>
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<div class="refsect1">
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<a name="id-1.3.34.5.62.3"></a><h2>Description</h2>
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<p>
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An ObjectTransform is a function type or a function
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pointer type where the return type Obj is a
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an object type and the arguments are
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Transforms. is_callable< Obj >::value
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must be false. The ObjectTransform, when applied,
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has the effect of constructing an object of type
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Obj' (see below), passing as construction parameters
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the result(s) of applying transform(s) Tn.
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</p>
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<p>
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The type Obj may be a template specialization representing
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a compile-time lambda expression. For instance, if Obj is
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std::pair< proto::_value, int >, the result type of the
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ObjectTransform is computed by replacing the type proto::_value
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with the result of applying the proto::_value transform. For
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given types Obj, Expr, State and Data, we can say that the
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type Obj' represents the type Obj after all nested transforms
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have been replaced with the results of applying the transforms
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with Expr, State and Data as transform arguments.
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</p>
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<p>
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If the type Obj is not a template specialization representing
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a compile-time lambda expression, then the result type Obj' is
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the same as Obj.
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</p>
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</div>
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<div class="refsect1">
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<a name="id-1.3.34.5.62.4"></a><h2>Notation</h2>
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<div class="variablelist"><dl class="variablelist">
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<dt><span class="term">Obj</span></dt>
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<dd>A type playing the role of object-type in the <a class="link" href="ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a> concept.</dd>
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<dt><span class="term">Tn</span></dt>
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<dd>A type playing the role of transform-type in the <a class="link" href="ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a> concept.</dd>
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<dt><span class="term">Expr</span></dt>
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<dd>A type playing the role of expression-type in the <a class="link" href="ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a> concept.</dd>
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<dt><span class="term">State</span></dt>
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<dd>A type playing the role of state-type in the <a class="link" href="ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a> concept.</dd>
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<dt><span class="term">Data</span></dt>
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<dd>A type playing the role of data-type in the <a class="link" href="ObjectTransform.html" title="Concept ObjectTransform">ObjectTransform</a> concept.</dd>
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<dt><span class="term"><code class="varname">expr</code></span></dt>
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<dd>Object of type Expr</dd>
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<dt><span class="term"><code class="varname">state</code></span></dt>
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<dd>Object of type State</dd>
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<dt><span class="term"><code class="varname">data</code></span></dt>
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<dd>Object of type Data</dd>
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</dl></div>
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</div>
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<div class="refsect1">
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<a name="id-1.3.34.5.62.5"></a><h2>Valid expressions</h2>
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<div class="informaltable"><table class="table">
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<colgroup>
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<col>
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<col>
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<col>
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<col>
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</colgroup>
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<thead><tr>
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<th>Name</th>
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<th>Expression</th>
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<th>Type</th>
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<th>Semantics</th>
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</tr></thead>
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<tbody><tr>
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<td><p>Apply Transform</p></td>
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<td><p>when< _, Obj(Tn...)>()(expr, state, data)</p></td>
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<td><p><span class="type">Obj'</span></p></td>
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<td><p>Applies the transform.</p></td>
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</tr></tbody>
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</table></div>
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</div>
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<div class="refsect1">
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<a name="id-1.3.34.5.62.6"></a><h2>Models</h2>
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<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><span class="simplelist"><span class="type">std::pair< boost::proto::_value, int >(boost::proto::_value, int())</span></span></li></ul></div>
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</div>
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</div>
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<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
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<td align="left"></td>
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<td align="right"><div class="copyright-footer">Copyright © 2008 Eric Niebler<p>
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Distributed under the Boost Software License, Version 1.0. (See accompanying
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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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</p>
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