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126 lines
3.7 KiB
HTML
126 lines
3.7 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN">
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<html>
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
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<title>Boost.Range Introduction </title>
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<link rel="stylesheet" href="style.css" type="text/css">
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</head>
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<body>
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<table border="0" >
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<tr>
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<td ><img src="cboost.gif" border="0" ></td>
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<td ><h1 align="center">Boost.Range</h1></td>
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</tr>
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</table>
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<h2>Introduction</h2>
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<p>
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This library makes it possible to treat different types as if they have
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implemented a subset of the container requirements (see §23.1of the C++
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standard). Formally, that subset is defined by the <a href="Range.htm"
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target="_self" >Range</a> concept. The subset deals mostly with iterator
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returning functions and nested <code >typedef</code>s. The main goal is to treat
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built-in arrays, standard containers, pairs of iterators and some iterators
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uniformly.
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</p>
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<p >
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The main advantages are
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<ul >
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<li >
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safe use of built-in arrays
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</li>
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<li >
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simpler implementation of generic container algorithms
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</li>
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<li >
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more flexible client code
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</li>
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<li >
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correct handling of null-terminated strings
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</li>
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</ul>
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</p>
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<p >
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Below are given a small example (the complete example can be found <a href="../test/algorithm_example.cpp" target="_self" >here</a>
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):
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<pre >
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//
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// Example: extracting bounds in generic algorithms
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//
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template< typename XRange, typename T >
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inline typename boost::iterator_of<XRange>::type
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find( XRange& c, const T& value )
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{
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return std::find( boost::begin( c ), boost::end( c ), value );
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}
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template< typename XRange, typename T >
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inline typename boost::const_iterator_of<XRange>::type
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find( const XRange& c, const T& value )
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{
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return std::find( boost::begin( c ), boost::end( c ), value );
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}
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//
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// replace first value and return its index
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//
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template< typename EC, typename T >
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inline typename boost::size_type_of< EC >::type
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my_generic_replace( EC& c, const T& value, const T& replacement )
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{
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typename boost::const_iterator_of<EC>::type found = find( c, value );
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*found = replacement;
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return std::distance( boost::begin( c ), found );
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}
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//
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// usage
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//
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std::vector<int> my_vector;
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typedef vector<int>::iterator iterator;
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std::pair<iterator,iterator> my_view( my_vector.begin(), my_vector.begin(
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) + N );
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char str[] = "a string";
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// ...
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std::cout << my_generic_replace( my_vector, 4, 2 )
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<< my_generic_replace( my_view, 4, 2 )
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<< my_generic_replace( str, 'a', 'b' );
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</pre>
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By using the free-standing functions and type-generators, the code automatically
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works for all the types supported by this library. Notice that we have to
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provide two version of <code >find()</code> since we cannot forward a non-const
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rvalue with reference arguments (see this article about <a href="http://std.dkuug.dk/jtc1/sc22/wg21/docs/papers/2002/n1385.htm" target="_self" >The
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Forwarding Problem</a> ).
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</p>
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<hr>
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<p>
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(C) Copyright Thorsten Ottosen 2003-2004
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</p>
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<br>
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<br>
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<br>
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<br>
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<br>
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<br>
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<br>
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<br>
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<br>
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</body>
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</html>
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