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 16 namespace boost { 17 namespace 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: filter_iterator()54 filter_iterator() { } 55 filter_iterator(Predicate f,Iterator x,Iterator end_=Iterator ())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 filter_iterator(Iterator x,Iterator end_=Iterator ())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> filter_iterator(filter_iterator<Predicate,OtherIterator> const & t,typename enable_if_convertible<OtherIterator,Iterator>::type * =0)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 predicate() const82 Predicate predicate() const { return m_predicate; } 83 end() const84 Iterator end() const { return m_end; } 85 86 private: increment()87 void increment() 88 { 89 ++(this->base_reference()); 90 satisfy_predicate(); 91 } 92 decrement()93 void decrement() 94 { 95 while(!this->m_predicate(*--(this->base_reference()))){}; 96 } 97 satisfy_predicate()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> make_filter_iterator(Predicate f,Iterator x,Iterator end=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> make_filter_iterator(typename iterators::enable_if<is_class<Predicate>,Iterator>::type x,Iterator end=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 130 131 using iterators::filter_iterator; 132 using iterators::make_filter_iterator; 133 134 } // namespace boost 135 136 #endif // BOOST_FILTER_ITERATOR_23022003THW_HPP 137