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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_ITERATOR_TRANSFORM_ITERATOR_HPP | |
12 | #define BOOST_COMPUTE_ITERATOR_TRANSFORM_ITERATOR_HPP | |
13 | ||
14 | #include <cstddef> | |
15 | #include <iterator> | |
16 | ||
17 | #include <boost/config.hpp> | |
18 | #include <boost/iterator/iterator_adaptor.hpp> | |
19 | ||
20 | #include <boost/compute/functional.hpp> | |
21 | #include <boost/compute/detail/meta_kernel.hpp> | |
22 | #include <boost/compute/detail/is_buffer_iterator.hpp> | |
23 | #include <boost/compute/detail/read_write_single_value.hpp> | |
24 | #include <boost/compute/iterator/detail/get_base_iterator_buffer.hpp> | |
25 | #include <boost/compute/type_traits/is_device_iterator.hpp> | |
26 | #include <boost/compute/type_traits/result_of.hpp> | |
27 | ||
28 | namespace boost { | |
29 | namespace compute { | |
30 | ||
31 | // forward declaration for transform_iterator | |
32 | template<class InputIterator, class UnaryFunction> | |
33 | class transform_iterator; | |
34 | ||
35 | namespace detail { | |
36 | ||
37 | // meta-function returning the value_type for a transform_iterator | |
38 | template<class InputIterator, class UnaryFunction> | |
39 | struct make_transform_iterator_value_type | |
40 | { | |
41 | typedef typename std::iterator_traits<InputIterator>::value_type value_type; | |
42 | ||
43 | typedef typename boost::compute::result_of<UnaryFunction(value_type)>::type type; | |
44 | }; | |
45 | ||
46 | // helper class which defines the iterator_adaptor super-class | |
47 | // type for transform_iterator | |
48 | template<class InputIterator, class UnaryFunction> | |
49 | class transform_iterator_base | |
50 | { | |
51 | public: | |
52 | typedef ::boost::iterator_adaptor< | |
53 | ::boost::compute::transform_iterator<InputIterator, UnaryFunction>, | |
54 | InputIterator, | |
55 | typename make_transform_iterator_value_type<InputIterator, UnaryFunction>::type, | |
56 | typename std::iterator_traits<InputIterator>::iterator_category, | |
57 | typename make_transform_iterator_value_type<InputIterator, UnaryFunction>::type | |
58 | > type; | |
59 | }; | |
60 | ||
61 | template<class InputIterator, class UnaryFunction, class IndexExpr> | |
62 | struct transform_iterator_index_expr | |
63 | { | |
64 | typedef typename | |
65 | make_transform_iterator_value_type< | |
66 | InputIterator, | |
67 | UnaryFunction | |
68 | >::type result_type; | |
69 | ||
70 | transform_iterator_index_expr(const InputIterator &input_iter, | |
71 | const UnaryFunction &transform_expr, | |
72 | const IndexExpr &index_expr) | |
73 | : m_input_iter(input_iter), | |
74 | m_transform_expr(transform_expr), | |
75 | m_index_expr(index_expr) | |
76 | { | |
77 | } | |
78 | ||
79 | InputIterator m_input_iter; | |
80 | UnaryFunction m_transform_expr; | |
81 | IndexExpr m_index_expr; | |
82 | }; | |
83 | ||
84 | template<class InputIterator, class UnaryFunction, class IndexExpr> | |
85 | inline meta_kernel& operator<<(meta_kernel &kernel, | |
86 | const transform_iterator_index_expr<InputIterator, | |
87 | UnaryFunction, | |
88 | IndexExpr> &expr) | |
89 | { | |
90 | return kernel << expr.m_transform_expr(expr.m_input_iter[expr.m_index_expr]); | |
91 | } | |
92 | ||
93 | } // end detail namespace | |
94 | ||
95 | /// \class transform_iterator | |
96 | /// \brief A transform iterator adaptor. | |
97 | /// | |
98 | /// The transform_iterator adaptor applies a unary function to each element | |
99 | /// produced from the underlying iterator when dereferenced. | |
100 | /// | |
101 | /// For example, to copy from an input range to an output range while taking | |
102 | /// the absolute value of each element: | |
103 | /// | |
104 | /// \snippet test/test_transform_iterator.cpp copy_abs | |
105 | /// | |
106 | /// \see buffer_iterator, make_transform_iterator() | |
107 | template<class InputIterator, class UnaryFunction> | |
108 | class transform_iterator : | |
109 | public detail::transform_iterator_base<InputIterator, UnaryFunction>::type | |
110 | { | |
111 | public: | |
112 | typedef typename | |
113 | detail::transform_iterator_base<InputIterator, | |
114 | UnaryFunction>::type super_type; | |
115 | typedef typename super_type::value_type value_type; | |
116 | typedef typename super_type::reference reference; | |
117 | typedef typename super_type::base_type base_type; | |
118 | typedef typename super_type::difference_type difference_type; | |
119 | typedef UnaryFunction unary_function; | |
120 | ||
121 | transform_iterator(InputIterator iterator, UnaryFunction transform) | |
122 | : super_type(iterator), | |
123 | m_transform(transform) | |
124 | { | |
125 | } | |
126 | ||
127 | transform_iterator(const transform_iterator<InputIterator, | |
128 | UnaryFunction> &other) | |
129 | : super_type(other.base()), | |
130 | m_transform(other.m_transform) | |
131 | { | |
132 | } | |
133 | ||
134 | transform_iterator<InputIterator, UnaryFunction>& | |
135 | operator=(const transform_iterator<InputIterator, | |
136 | UnaryFunction> &other) | |
137 | { | |
138 | if(this != &other){ | |
139 | super_type::operator=(other); | |
140 | ||
141 | m_transform = other.m_transform; | |
142 | } | |
143 | ||
144 | return *this; | |
145 | } | |
146 | ||
147 | ~transform_iterator() | |
148 | { | |
149 | } | |
150 | ||
151 | size_t get_index() const | |
152 | { | |
153 | return super_type::base().get_index(); | |
154 | } | |
155 | ||
156 | const buffer& get_buffer() const | |
157 | { | |
158 | return detail::get_base_iterator_buffer(*this); | |
159 | } | |
160 | ||
161 | template<class IndexExpression> | |
162 | detail::transform_iterator_index_expr<InputIterator, UnaryFunction, IndexExpression> | |
163 | operator[](const IndexExpression &expr) const | |
164 | { | |
165 | return detail::transform_iterator_index_expr<InputIterator, | |
166 | UnaryFunction, | |
167 | IndexExpression>(super_type::base(), | |
168 | m_transform, | |
169 | expr); | |
170 | } | |
171 | ||
172 | private: | |
173 | friend class ::boost::iterator_core_access; | |
174 | ||
175 | reference dereference() const | |
176 | { | |
177 | const context &context = super_type::base().get_buffer().get_context(); | |
178 | command_queue queue(context, context.get_device()); | |
179 | ||
180 | detail::meta_kernel k("read"); | |
181 | size_t output_arg = k.add_arg<value_type *>(memory_object::global_memory, "output"); | |
182 | k << "*output = " << m_transform(super_type::base()[k.lit(0)]) << ";"; | |
183 | ||
184 | kernel kernel = k.compile(context); | |
185 | ||
186 | buffer output_buffer(context, sizeof(value_type)); | |
187 | ||
188 | kernel.set_arg(output_arg, output_buffer); | |
189 | ||
190 | queue.enqueue_task(kernel); | |
191 | ||
192 | return detail::read_single_value<value_type>(output_buffer, queue); | |
193 | } | |
194 | ||
195 | private: | |
196 | UnaryFunction m_transform; | |
197 | }; | |
198 | ||
199 | /// Returns a transform_iterator for \p iterator with \p transform. | |
200 | /// | |
201 | /// \param iterator the underlying iterator | |
202 | /// \param transform the unary transform function | |
203 | /// | |
204 | /// \return a \c transform_iterator for \p iterator with \p transform | |
205 | /// | |
206 | /// For example, to create an iterator which returns the square-root of each | |
207 | /// value in a \c vector<int>: | |
208 | /// \code | |
209 | /// auto sqrt_iterator = make_transform_iterator(vec.begin(), sqrt<int>()); | |
210 | /// \endcode | |
211 | template<class InputIterator, class UnaryFunction> | |
212 | inline transform_iterator<InputIterator, UnaryFunction> | |
213 | make_transform_iterator(InputIterator iterator, UnaryFunction transform) | |
214 | { | |
215 | return transform_iterator<InputIterator, | |
216 | UnaryFunction>(iterator, transform); | |
217 | } | |
218 | ||
219 | /// \internal_ (is_device_iterator specialization for transform_iterator) | |
220 | template<class InputIterator, class UnaryFunction> | |
221 | struct is_device_iterator< | |
222 | transform_iterator<InputIterator, UnaryFunction> > : boost::true_type {}; | |
223 | ||
224 | } // end compute namespace | |
225 | } // end boost namespace | |
226 | ||
227 | #endif // BOOST_COMPUTE_ITERATOR_TRANSFORM_ITERATOR_HPP |