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61 lines
2.9 KiB
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61 lines
2.9 KiB
HTML
<!doctype html public "-//ietf//dtd html//en">
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<html><head><title>boost::mpl::Reference/transform view</title>
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<link rel="stylesheet" href="../mpl_wiki.css">
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</head><body bgcolor="white">
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<h1><a href="../Table_of_Content.html"><img src="../mpl_logo.jpg" alt="[Home]" border=0 align="right"></a>transform_view</h1><h3>Synopsis</h3>
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<p>
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<pre>
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template<
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typename Sequence
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, typename F
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>
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struct transform_view
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{
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};
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</pre>
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<p>
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<h3>Description</h3>
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<p>
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<code>transform_view</code> is a sequence wrapper that allows one to operate on the transformed sequence without actually creating one.
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<p>
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<h3>Definition</h3>
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<p>
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<pre>
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#include "<a href="../../../../../\boost/mpl/transform_view.hpp">boost/mpl/transform_view.hpp</a>"
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</pre>
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<p>
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<h3>Parameters</h3>
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<table border="1">
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<tr><th> Parameter </th><th> Requirement </th><th> Description </th></tr>
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<tr><td><code>Sequence</code></td><td>A model of <a href="../Sequence.html">Sequence</a></td><td>A sequence to wrap. </td></tr>
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<tr><td><code>F</code></td><td>A model of unary [Lambda Expression]</td><td>A transformation metafunction. </td></tr>
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</table>
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<p>
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<h3>Expression semantics</h3>
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<p>
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<table border="1">
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<tr><th> Expression </th><th> Expression type </th><th> Precondition </th><th> Semantics </th><th> Postcondition </th></tr>
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<tr><td><code>typedef transform_view<Sequence,F> s;</code></td><td>A model of <a href="../Sequence.html">Sequence</a></td><td></td><td><code>s</code> is a sequence such that for each <code>i</code> in <code>[<a href="../Reference/begin.html">begin</a><s>::type, <a href="../Reference/end.html">end</a><s>::type)</code> and for each <code>j</code> in <code>[<a href="../Reference/begin.html">begin</a><Sequence>::type, <a href="../Reference/end.html">end</a><Sequence>::type)</code> <code>i::type</code> is identical to <code>apply< lambda<F>::type, j::type >::type</code>.</td><td><code><a href="../Reference/size.html">size</a><Sequence>::type::value == <a href="../Reference/size.html">size</a><s>::type::value</code>. </td></tr>
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</table>
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<p>
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<h3>Complexity</h3>
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<p>
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Amortized constant time.
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<p>
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<h3>Example</h3>
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<p>
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Finds the largest type in a sequence.
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<p>
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<pre>
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typedef <a href="../Reference/list.html">list</a><int,long,char,char[50],double> types;
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typedef max_element<
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transform_view< types, size_of<_> >
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>::type iter;
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BOOST_STATIC_ASSERT(iter::type::value == 50);
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</pre>
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<p>
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<h3>See also</h3>
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<p>
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<a href="../Sequences.html">Sequences</a>, <code><a href="../Reference/filter_view.html">filter_view</a></code>, <code><a href="../Reference/list.html">list</a></code>, <code>max_element</code>
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<p><hr>
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<a href="../Table_of_Content.html">Table of Content</a> | <a href="../Reference.html">Reference</a><br>Last edited July 23, 2002 3:23 am</body></html> |