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1 | // Boost.Range library |
2 | // | |
3 | // Copyright Thorsten Ottosen, Neil Groves 2006 - 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 | #ifndef BOOST_RANGE_ADAPTOR_FILTERED_HPP | |
12 | #define BOOST_RANGE_ADAPTOR_FILTERED_HPP | |
13 | ||
14 | #include <boost/range/adaptor/argument_fwd.hpp> | |
15 | #include <boost/range/detail/default_constructible_unary_fn.hpp> | |
16 | #include <boost/range/iterator_range.hpp> | |
17 | #include <boost/range/concepts.hpp> | |
18 | #include <boost/iterator/filter_iterator.hpp> | |
19 | ||
20 | namespace boost | |
21 | { | |
22 | namespace range_detail | |
23 | { | |
24 | template< class P, class R > | |
25 | struct filtered_range : | |
26 | boost::iterator_range< | |
27 | boost::filter_iterator< | |
28 | typename default_constructible_unary_fn_gen<P, bool>::type, | |
29 | typename range_iterator<R>::type | |
30 | > | |
31 | > | |
32 | { | |
33 | private: | |
34 | typedef boost::iterator_range< | |
35 | boost::filter_iterator< | |
36 | typename default_constructible_unary_fn_gen<P, bool>::type, | |
37 | typename range_iterator<R>::type | |
38 | > | |
39 | > base; | |
40 | public: | |
41 | typedef typename default_constructible_unary_fn_gen<P, bool>::type | |
42 | pred_t; | |
43 | ||
44 | filtered_range(P p, R& r) | |
45 | : base(make_filter_iterator(pred_t(p), | |
46 | boost::begin(r), boost::end(r)), | |
47 | make_filter_iterator(pred_t(p), | |
48 | boost::end(r), boost::end(r))) | |
49 | { } | |
50 | }; | |
51 | ||
52 | template< class T > | |
53 | struct filter_holder : holder<T> | |
54 | { | |
55 | filter_holder( T r ) : holder<T>(r) | |
56 | { } | |
57 | }; | |
58 | ||
59 | template< class SinglePassRange, class Predicate > | |
60 | inline filtered_range<Predicate, SinglePassRange> | |
61 | operator|(SinglePassRange& r, | |
62 | const filter_holder<Predicate>& f) | |
63 | { | |
64 | BOOST_RANGE_CONCEPT_ASSERT((SinglePassRangeConcept<SinglePassRange>)); | |
65 | return filtered_range<Predicate, SinglePassRange>( f.val, r ); | |
66 | } | |
67 | ||
68 | template< class SinglePassRange, class Predicate > | |
69 | inline filtered_range<Predicate, const SinglePassRange> | |
70 | operator|(const SinglePassRange& r, | |
71 | const filter_holder<Predicate>& f ) | |
72 | { | |
73 | BOOST_RANGE_CONCEPT_ASSERT(( | |
74 | SinglePassRangeConcept<const SinglePassRange>)); | |
75 | return filtered_range<Predicate, const SinglePassRange>( f.val, r ); | |
76 | } | |
77 | ||
78 | } // 'range_detail' | |
79 | ||
80 | // Unusual use of 'using' is intended to bring filter_range into the boost namespace | |
81 | // while leaving the mechanics of the '|' operator in range_detail and maintain | |
82 | // argument dependent lookup. | |
83 | // filter_range logically needs to be in the boost namespace to allow user of | |
84 | // the library to define the return type for filter() | |
85 | using range_detail::filtered_range; | |
86 | ||
87 | namespace adaptors | |
88 | { | |
89 | namespace | |
90 | { | |
91 | const range_detail::forwarder<range_detail::filter_holder> | |
92 | filtered = | |
93 | range_detail::forwarder<range_detail::filter_holder>(); | |
94 | } | |
95 | ||
96 | template<class SinglePassRange, class Predicate> | |
97 | inline filtered_range<Predicate, SinglePassRange> | |
98 | filter(SinglePassRange& rng, Predicate filter_pred) | |
99 | { | |
100 | BOOST_RANGE_CONCEPT_ASSERT(( | |
101 | SinglePassRangeConcept<SinglePassRange>)); | |
102 | ||
103 | return range_detail::filtered_range< | |
104 | Predicate, SinglePassRange>( filter_pred, rng ); | |
105 | } | |
106 | ||
107 | template<class SinglePassRange, class Predicate> | |
108 | inline filtered_range<Predicate, const SinglePassRange> | |
109 | filter(const SinglePassRange& rng, Predicate filter_pred) | |
110 | { | |
111 | BOOST_RANGE_CONCEPT_ASSERT(( | |
112 | SinglePassRangeConcept<const SinglePassRange>)); | |
113 | ||
114 | return range_detail::filtered_range< | |
115 | Predicate, const SinglePassRange>( filter_pred, rng ); | |
116 | } | |
117 | } // 'adaptors' | |
118 | ||
119 | } | |
120 | ||
121 | #endif |