1// (C) Copyright David Abrahams 2002.
2// (C) Copyright Jeremy Siek 2002.
3// (C) Copyright Thomas Witt 2002.
4// Distributed under the Boost Software License, Version 1.0. (See
5// accompanying file LICENSE_1_0.txt or copy at
6// http://www.boost.org/LICENSE_1_0.txt)
7#ifndef BOOST_FILTER_ITERATOR_23022003THW_HPP
8#define BOOST_FILTER_ITERATOR_23022003THW_HPP
9
10#include <boost/iterator/iterator_adaptor.hpp>
11#include <boost/iterator/iterator_categories.hpp>
12
13#include <boost/type_traits/is_class.hpp>
14#include <boost/static_assert.hpp>
15
16namespace boost {
17namespace iterators {
18
19 template <class Predicate, class Iterator>
20 class filter_iterator;
21
22 namespace detail
23 {
24 template <class Predicate, class Iterator>
25 struct filter_iterator_base
26 {
27 typedef iterator_adaptor<
28 filter_iterator<Predicate, Iterator>
29 , Iterator
30 , use_default
31 , typename mpl::if_<
32 is_convertible<
33 typename iterator_traversal<Iterator>::type
34 , random_access_traversal_tag
35 >
36 , bidirectional_traversal_tag
37 , use_default
38 >::type
39 > type;
40 };
41 }
42
43 template <class Predicate, class Iterator>
44 class filter_iterator
45 : public detail::filter_iterator_base<Predicate, Iterator>::type
46 {
47 typedef typename detail::filter_iterator_base<
48 Predicate, Iterator
49 >::type super_t;
50
51 friend class iterator_core_access;
52
53 public:
54 filter_iterator() { }
55
56 filter_iterator(Predicate f, Iterator x, Iterator end_ = Iterator())
57 : super_t(x), m_predicate(f), m_end(end_)
58 {
59 satisfy_predicate();
60 }
61
62 filter_iterator(Iterator x, Iterator end_ = Iterator())
63 : super_t(x), m_predicate(), m_end(end_)
64 {
65 // Pro8 is a little too aggressive about instantiating the
66 // body of this function.
67#if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
68 // Don't allow use of this constructor if Predicate is a
69 // function pointer type, since it will be 0.
70 BOOST_STATIC_ASSERT(is_class<Predicate>::value);
71#endif
72 satisfy_predicate();
73 }
74
75 template<class OtherIterator>
76 filter_iterator(
77 filter_iterator<Predicate, OtherIterator> const& t
78 , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
79 )
80 : super_t(t.base()), m_predicate(t.predicate()), m_end(t.end()) {}
81
82 Predicate predicate() const { return m_predicate; }
83
84 Iterator end() const { return m_end; }
85
86 private:
87 void increment()
88 {
89 ++(this->base_reference());
90 satisfy_predicate();
91 }
92
93 void decrement()
94 {
95 while(!this->m_predicate(*--(this->base_reference()))){};
96 }
97
98 void satisfy_predicate()
99 {
100 while (this->base() != this->m_end && !this->m_predicate(*this->base()))
101 ++(this->base_reference());
102 }
103
104 // Probably should be the initial base class so it can be
105 // optimized away via EBO if it is an empty class.
106 Predicate m_predicate;
107 Iterator m_end;
108 };
109
110 template <class Predicate, class Iterator>
111 inline filter_iterator<Predicate,Iterator>
112 make_filter_iterator(Predicate f, Iterator x, Iterator end = Iterator())
113 {
114 return filter_iterator<Predicate,Iterator>(f,x,end);
115 }
116
117 template <class Predicate, class Iterator>
118 inline filter_iterator<Predicate,Iterator>
119 make_filter_iterator(
120 typename iterators::enable_if<
121 is_class<Predicate>
122 , Iterator
123 >::type x
124 , Iterator end = Iterator())
125 {
126 return filter_iterator<Predicate,Iterator>(x,end);
127 }
128
129} // namespace iterators
130
131using iterators::filter_iterator;
132using iterators::make_filter_iterator;
133
134} // namespace boost
135
136#endif // BOOST_FILTER_ITERATOR_23022003THW_HPP
137