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1 | // (C) Copyright Jeremy Siek 2001. |
2 | // Distributed under the Boost Software License, Version 1.0. (See | |
3 | // accompanying file LICENSE_1_0.txt or copy at | |
4 | // http://www.boost.org/LICENSE_1_0.txt) | |
5 | ||
6 | #ifndef BOOST_SHADOW_ITERATOR_HPP | |
7 | #define BOOST_SHADOW_ITERATOR_HPP | |
8 | ||
9 | #include <boost/iterator_adaptors.hpp> | |
10 | #include <boost/operators.hpp> | |
11 | ||
12 | namespace boost { | |
13 | ||
14 | namespace detail { | |
15 | ||
16 | template <class A, class B, class D> | |
17 | class shadow_proxy | |
18 | : boost::operators< shadow_proxy<A,B,D> > | |
19 | { | |
20 | typedef shadow_proxy self; | |
21 | public: | |
22 | inline shadow_proxy(A aa, B bb) : a(aa), b(bb) { } | |
23 | inline shadow_proxy(const self& x) : a(x.a), b(x.b) { } | |
24 | template <class Self> | |
25 | inline shadow_proxy(Self x) : a(x.a), b(x.b) { } | |
26 | inline self& operator=(const self& x) { a = x.a; b = x.b; return *this; } | |
27 | inline self& operator++() { ++a; return *this; } | |
28 | inline self& operator--() { --a; return *this; } | |
29 | inline self& operator+=(const self& x) { a += x.a; return *this; } | |
30 | inline self& operator-=(const self& x) { a -= x.a; return *this; } | |
31 | inline self& operator*=(const self& x) { a *= x.a; return *this; } | |
32 | inline self& operator/=(const self& x) { a /= x.a; return *this; } | |
33 | inline self& operator%=(const self& x) { return *this; } // JGS | |
34 | inline self& operator&=(const self& x) { return *this; } // JGS | |
35 | inline self& operator|=(const self& x) { return *this; } // JGS | |
36 | inline self& operator^=(const self& x) { return *this; } // JGS | |
37 | inline friend D operator-(const self& x, const self& y) { | |
38 | return x.a - y.a; | |
39 | } | |
40 | inline bool operator==(const self& x) const { return a == x.a; } | |
41 | inline bool operator<(const self& x) const { return a < x.a; } | |
42 | // protected: | |
43 | A a; | |
44 | B b; | |
45 | }; | |
46 | ||
47 | struct shadow_iterator_policies | |
48 | { | |
49 | template <typename iter_pair> | |
50 | void initialize(const iter_pair&) { } | |
51 | ||
52 | template <typename Iter> | |
53 | typename Iter::reference dereference(const Iter& i) const { | |
54 | typedef typename Iter::reference R; | |
55 | return R(*i.base().first, *i.base().second); | |
56 | } | |
57 | template <typename Iter> | |
58 | bool equal(const Iter& p1, const Iter& p2) const { | |
59 | return p1.base().first == p2.base().first; | |
60 | } | |
61 | template <typename Iter> | |
62 | void increment(Iter& i) { ++i.base().first; ++i.base().second; } | |
63 | ||
64 | template <typename Iter> | |
65 | void decrement(Iter& i) { --i.base().first; --i.base().second; } | |
66 | ||
67 | template <typename Iter> | |
68 | bool less(const Iter& x, const Iter& y) const { | |
69 | return x.base().first < y.base().first; | |
70 | } | |
71 | template <typename Iter> | |
72 | typename Iter::difference_type | |
73 | distance(const Iter& x, const Iter& y) const { | |
74 | return y.base().first - x.base().first; | |
75 | } | |
76 | template <typename D, typename Iter> | |
77 | void advance(Iter& p, D n) { p.base().first += n; p.base().second += n; } | |
78 | }; | |
79 | ||
80 | } // namespace detail | |
81 | ||
82 | template <typename IterA, typename IterB> | |
83 | struct shadow_iterator_generator { | |
84 | ||
85 | // To use the iterator_adaptor we can't derive from | |
86 | // random_access_iterator because we don't have a real reference. | |
87 | // However, we want the STL algorithms to treat the shadow | |
88 | // iterator like a random access iterator. | |
89 | struct shadow_iterator_tag : public std::input_iterator_tag { | |
90 | operator std::random_access_iterator_tag() { | |
91 | return std::random_access_iterator_tag(); | |
92 | }; | |
93 | }; | |
94 | typedef typename std::iterator_traits<IterA>::value_type Aval; | |
95 | typedef typename std::iterator_traits<IterB>::value_type Bval; | |
96 | typedef typename std::iterator_traits<IterA>::reference Aref; | |
97 | typedef typename std::iterator_traits<IterB>::reference Bref; | |
98 | typedef typename std::iterator_traits<IterA>::difference_type D; | |
99 | typedef detail::shadow_proxy<Aval,Bval,Aval> V; | |
100 | typedef detail::shadow_proxy<Aref,Bref,Aval> R; | |
101 | typedef iterator_adaptor< std::pair<IterA, IterB>, | |
102 | detail::shadow_iterator_policies, | |
103 | V, R, V*, shadow_iterator_tag, | |
104 | D> type; | |
105 | }; | |
106 | ||
107 | // short cut for creating a shadow iterator | |
108 | template <class IterA, class IterB> | |
109 | inline typename shadow_iterator_generator<IterA,IterB>::type | |
110 | make_shadow_iter(IterA a, IterB b) { | |
111 | typedef typename shadow_iterator_generator<IterA,IterB>::type Iter; | |
112 | return Iter(std::make_pair(a,b)); | |
113 | } | |
114 | ||
115 | template <class Cmp> | |
116 | struct shadow_cmp { | |
117 | inline shadow_cmp(const Cmp& c) : cmp(c) { } | |
118 | template <class ShadowProxy1, class ShadowProxy2> | |
119 | inline bool operator()(const ShadowProxy1& x, const ShadowProxy2& y) const | |
120 | { | |
121 | return cmp(x.a, y.a); | |
122 | } | |
123 | Cmp cmp; | |
124 | }; | |
125 | ||
126 | } // namespace boost | |
127 | ||
128 | namespace std { | |
129 | template <class A1, class B1, class D1, | |
130 | class A2, class B2, class D2> | |
131 | void swap(boost::detail::shadow_proxy<A1&,B1&,D1> x, | |
132 | boost::detail::shadow_proxy<A2&,B2&,D2> y) | |
133 | { | |
134 | std::swap(x.a, y.a); | |
135 | std::swap(x.b, y.b); | |
136 | } | |
137 | } | |
138 | ||
139 | #endif // BOOST_SHADOW_ITERATOR_HPP |