1 | // (C) Copyright David Abrahams 2002.
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2 | // (C) Copyright Jeremy Siek 2002.
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3 | // (C) Copyright Thomas Witt 2002.
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4 | // Distributed under the Boost Software License, Version 1.0. (See
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5 | // accompanying file LICENSE_1_0.txt or copy at
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6 | // http://www.boost.org/LICENSE_1_0.txt)
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7 | #ifndef BOOST_FILTER_ITERATOR_23022003THW_HPP
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8 | #define BOOST_FILTER_ITERATOR_23022003THW_HPP
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9 |
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10 | #include <boost/iterator.hpp>
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11 | #include <boost/iterator/iterator_adaptor.hpp>
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12 | #include <boost/iterator/iterator_categories.hpp>
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13 |
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14 | #include <boost/type_traits/is_class.hpp>
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15 | #include <boost/static_assert.hpp>
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16 |
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17 | namespace boost
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18 | {
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19 | template <class Predicate, class Iterator>
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20 | class filter_iterator;
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21 |
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22 | namespace detail
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23 | {
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24 | template <class Predicate, class Iterator>
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25 | struct filter_iterator_base
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26 | {
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27 | typedef iterator_adaptor<
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28 | filter_iterator<Predicate, Iterator>
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29 | , Iterator
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30 | , use_default
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31 | , typename mpl::if_<
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32 | is_convertible<
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33 | typename iterator_traversal<Iterator>::type
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34 | , random_access_traversal_tag
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35 | >
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36 | , bidirectional_traversal_tag
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37 | , use_default
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38 | >::type
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39 | > type;
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40 | };
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41 | }
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42 |
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43 | template <class Predicate, class Iterator>
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44 | class filter_iterator
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45 | : public detail::filter_iterator_base<Predicate, Iterator>::type
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46 | {
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47 | typedef typename detail::filter_iterator_base<
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48 | Predicate, Iterator
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49 | >::type super_t;
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50 |
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51 | friend class iterator_core_access;
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52 |
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53 | public:
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54 | filter_iterator() { }
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55 |
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56 | filter_iterator(Predicate f, Iterator x, Iterator end = Iterator())
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57 | : super_t(x), m_predicate(f), m_end(end)
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58 | {
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59 | satisfy_predicate();
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60 | }
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61 |
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62 | filter_iterator(Iterator x, Iterator end = Iterator())
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63 | : super_t(x), m_predicate(), m_end(end)
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64 | {
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65 | // Pro8 is a little too aggressive about instantiating the
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66 | // body of this function.
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67 | #if !BOOST_WORKAROUND(__MWERKS__, BOOST_TESTED_AT(0x3003))
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68 | // Don't allow use of this constructor if Predicate is a
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69 | // function pointer type, since it will be 0.
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70 | BOOST_STATIC_ASSERT(is_class<Predicate>::value);
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71 | #endif
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72 | satisfy_predicate();
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73 | }
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74 |
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75 | template<class OtherIterator>
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76 | filter_iterator(
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77 | filter_iterator<Predicate, OtherIterator> const& t
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78 | , typename enable_if_convertible<OtherIterator, Iterator>::type* = 0
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79 | )
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80 | : super_t(t.base()), m_predicate(t.predicate()), m_end(t.end()) {}
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81 |
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82 | Predicate predicate() const { return m_predicate; }
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83 |
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84 | Iterator end() const { return m_end; }
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85 |
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86 | private:
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87 | void increment()
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88 | {
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89 | ++(this->base_reference());
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90 | satisfy_predicate();
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91 | }
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92 |
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93 | void decrement()
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94 | {
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95 | while(!this->m_predicate(*--(this->base_reference()))){};
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96 | }
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97 |
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98 | void satisfy_predicate()
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99 | {
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100 | while (this->base() != this->m_end && !this->m_predicate(*this->base()))
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101 | ++(this->base_reference());
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102 | }
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103 |
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104 | // Probably should be the initial base class so it can be
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105 | // optimized away via EBO if it is an empty class.
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106 | Predicate m_predicate;
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107 | Iterator m_end;
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108 | };
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109 |
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110 | template <class Predicate, class Iterator>
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111 | filter_iterator<Predicate,Iterator>
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112 | make_filter_iterator(Predicate f, Iterator x, Iterator end = Iterator())
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113 | {
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114 | return filter_iterator<Predicate,Iterator>(f,x,end);
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115 | }
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116 |
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117 | template <class Predicate, class Iterator>
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118 | filter_iterator<Predicate,Iterator>
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119 | make_filter_iterator(
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120 | typename iterators::enable_if<
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121 | is_class<Predicate>
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122 | , Iterator
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123 | >::type x
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124 | , Iterator end = Iterator()
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125 | #if BOOST_WORKAROUND(BOOST_MSVC, == 1200)
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126 | , Predicate* = 0
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127 | #endif
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128 | )
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129 | {
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130 | return filter_iterator<Predicate,Iterator>(x,end);
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131 | }
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132 |
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133 | } // namespace boost
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134 |
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135 | #endif // BOOST_FILTER_ITERATOR_23022003THW_HPP
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