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 |
122 | |