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
20namespace 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

source code of boost/libs/range/include/boost/range/adaptor/filtered.hpp