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1 | // Boost.Range library |
2 | // | |
3 | // Copyright Thorsten Ottosen 2003-2008. Use, modification and | |
4 | // distribution is subject to the Boost Software License, Version | |
5 | // 1.0. (See accompanying file LICENSE_1_0.txt or copy at | |
6 | // http://www.boost.org/LICENSE_1_0.txt) | |
7 | // | |
8 | // For more information, see http://www.boost.org/libs/range/ | |
9 | // | |
10 | ||
11 | #include <boost/range.hpp> | |
12 | #include <iterator> // for std::iterator_traits, std::distance() | |
13 | ||
14 | namespace Foo | |
15 | { | |
16 | // | |
17 | // Our sample UDT. A 'Pair' | |
18 | // will work as a range when the stored | |
19 | // elements are iterators. | |
20 | // | |
21 | template< class T > | |
22 | struct Pair | |
23 | { | |
24 | T first, last; | |
25 | }; | |
26 | ||
27 | } // namespace 'Foo' | |
28 | ||
29 | namespace boost | |
30 | { | |
31 | // | |
32 | // Specialize metafunctions. We must include the range.hpp header. | |
33 | // We must open the 'boost' namespace. | |
34 | // | |
35 | /* | |
36 | template< class T > | |
37 | struct range_value< Foo::Pair<T> > | |
38 | { | |
39 | typedef typename std::iterator_traits<T>::value_type type; | |
40 | }; | |
41 | */ | |
42 | ||
43 | template< class T > | |
44 | struct range_iterator< Foo::Pair<T> > | |
45 | { | |
46 | typedef T type; | |
47 | }; | |
48 | ||
49 | template< class T > | |
50 | struct range_const_iterator< Foo::Pair<T> > | |
51 | { | |
52 | // | |
53 | // Remark: this is defined similar to 'range_iterator' | |
54 | // because the 'Pair' type does not distinguish | |
55 | // between an iterator and a const_iterator. | |
56 | // | |
57 | typedef T type; | |
58 | }; | |
59 | ||
60 | /* | |
61 | template< class T > | |
62 | struct range_difference< Foo::Pair<T> > | |
63 | { | |
64 | typedef typename std::iterator_traits<T>::difference_type type; | |
65 | }; | |
66 | */ | |
67 | ||
68 | template< class T > | |
69 | struct range_size< Foo::Pair<T> > | |
70 | { | |
71 | int static_assertion[ sizeof( std::size_t ) >= | |
72 | sizeof( typename range_difference< Foo::Pair<T> >::type ) ]; | |
73 | typedef std::size_t type; | |
74 | }; | |
75 | ||
76 | } // namespace 'boost' | |
77 | ||
78 | namespace Foo | |
79 | { | |
80 | // | |
81 | // The required functions. These should be defined in | |
82 | // the same namespace as 'Pair', in this case | |
83 | // in namespace 'Foo'. | |
84 | // | |
85 | ||
86 | template< class T > | |
87 | inline T boost_range_begin( Pair<T>& x ) | |
88 | { | |
89 | return x.first; | |
90 | } | |
91 | ||
92 | template< class T > | |
93 | inline T boost_range_begin( const Pair<T>& x ) | |
94 | { | |
95 | return x.first; | |
96 | } | |
97 | ||
98 | template< class T > | |
99 | inline T boost_range_end( Pair<T>& x ) | |
100 | { | |
101 | return x.last; | |
102 | } | |
103 | ||
104 | template< class T > | |
105 | inline T boost_range_end( const Pair<T>& x ) | |
106 | { | |
107 | return x.last; | |
108 | } | |
109 | ||
110 | template< class T > | |
111 | inline typename boost::range_size< Pair<T> >::type | |
112 | boost_range_size( const Pair<T>& x ) | |
113 | { | |
114 | return std::distance(x.first,x.last); | |
115 | } | |
116 | ||
117 | } // namespace 'Foo' | |
118 | ||
119 | #include <vector> | |
120 | ||
121 | int main() | |
122 | { | |
123 | typedef std::vector<int>::iterator iter; | |
124 | std::vector<int> vec; | |
125 | vec.push_back( 42 ); | |
126 | Foo::Pair<iter> pair = { vec.begin(), vec.end() }; | |
127 | const Foo::Pair<iter>& cpair = pair; | |
128 | // | |
129 | // Notice that we call 'begin' etc with qualification. | |
130 | // | |
131 | iter i = boost::begin( pair ); | |
132 | iter e = boost::end( pair ); | |
133 | i = boost::begin( cpair ); | |
134 | e = boost::end( cpair ); | |
135 | boost::range_size< Foo::Pair<iter> >::type s = boost::size( pair ); | |
136 | s = boost::size( cpair ); | |
137 | boost::range_const_reverse_iterator< Foo::Pair<iter> >::type | |
138 | ri = boost::rbegin( cpair ), | |
139 | re = boost::rend( cpair ); | |
140 | ||
141 | // | |
142 | // Test metafunctions | |
143 | // | |
144 | ||
145 | boost::range_value< Foo::Pair<iter> >::type | |
146 | v = *boost::begin(pair); | |
147 | ||
148 | boost::range_difference< Foo::Pair<iter> >::type | |
149 | d = boost::end(pair) - boost::begin(pair); | |
150 | } | |
151 |