1 //---------------------------------------------------------------------------//
2 // Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
3 //
4 // Distributed under the Boost Software License, Version 1.0
5 // See accompanying file LICENSE_1_0.txt or copy at
6 // http://www.boost.org/LICENSE_1_0.txt
7 //
8 // See http://boostorg.github.com/compute for more information.
9 //---------------------------------------------------------------------------//
10 
11 #ifndef BOOST_COMPUTE_DETAIL_IS_CONTIGUOUS_ITERATOR_HPP
12 #define BOOST_COMPUTE_DETAIL_IS_CONTIGUOUS_ITERATOR_HPP
13 
14 #include <vector>
15 #include <valarray>
16 
17 #include <boost/config.hpp>
18 #include <boost/type_traits.hpp>
19 #include <boost/utility/enable_if.hpp>
20 
21 namespace boost {
22 namespace compute {
23 namespace detail {
24 
25 // default = false
26 template<class Iterator, class Enable = void>
27 struct _is_contiguous_iterator : public boost::false_type {};
28 
29 // std::vector<T>::iterator = true
30 template<class Iterator>
31 struct _is_contiguous_iterator<
32     Iterator,
33     typename boost::enable_if<
34         typename boost::is_same<
35             Iterator,
36             typename std::vector<typename Iterator::value_type>::iterator
37         >::type
38     >::type
39 > : public boost::true_type {};
40 
41 // std::vector<T>::const_iterator = true
42 template<class Iterator>
43 struct _is_contiguous_iterator<
44     Iterator,
45     typename boost::enable_if<
46         typename boost::is_same<
47             Iterator,
48             typename std::vector<typename Iterator::value_type>::const_iterator
49         >::type
50     >::type
51 > : public boost::true_type {};
52 
53 // std::valarray<T>::iterator = true
54 template<class Iterator>
55 struct _is_contiguous_iterator<
56     Iterator,
57     typename boost::enable_if<
58         typename boost::is_same<
59             Iterator,
60             typename std::valarray<typename Iterator::value_type>::iterator
61         >::type
62     >::type
63 > : public boost::true_type {};
64 
65 // std::valarray<T>::const_iterator = true
66 template<class Iterator>
67 struct _is_contiguous_iterator<
68     Iterator,
69     typename boost::enable_if<
70         typename boost::is_same<
71             Iterator,
72             typename std::valarray<typename Iterator::value_type>::const_iterator
73         >::type
74     >::type
75 > : public boost::true_type {};
76 
77 // T* = true
78 template<class Iterator>
79 struct _is_contiguous_iterator<
80     Iterator,
81     typename boost::enable_if<
82         boost::is_pointer<Iterator>
83     >::type
84 > : public boost::true_type {};
85 
86 // the is_contiguous_iterator meta-function returns true if Iterator points
87 // to a range of contiguous values. examples of contiguous iterators are
88 // std::vector<>::iterator and float*. examples of non-contiguous iterators
89 // are std::set<>::iterator and std::insert_iterator<>.
90 //
91 // the implementation consists of two phases. the first checks that value_type
92 // for the iterator is not void. this must be done as for many containers void
93 // is not a valid value_type (ex. std::vector<void>::iterator is not valid).
94 // after ensuring a non-void value_type, the _is_contiguous_iterator function
95 // is invoked. it has specializations retuning true for all (known) contiguous
96 // iterators types and a default value of false.
97 template<class Iterator, class Enable = void>
98 struct is_contiguous_iterator :
99     public _is_contiguous_iterator<
100         typename boost::remove_cv<Iterator>::type
101     > {};
102 
103 // value_type of void = false
104 template<class Iterator>
105 struct is_contiguous_iterator<
106     Iterator,
107     typename boost::enable_if<
108         typename boost::is_void<
109             typename Iterator::value_type
110         >::type
111     >::type
112 > : public boost::false_type {};
113 
114 } // end detail namespace
115 } // end compute namespace
116 } // end boost namespace
117 
118 #endif // BOOST_COMPUTE_DETAIL_IS_CONTIGUOUS_ITERATOR_HPP
119