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
transform_iterator_index_exprboost::compute::detail::transform_iterator_index_expr70 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 const InputIterator m_input_iter;
80 const UnaryFunction m_transform_expr;
81 const IndexExpr m_index_expr;
82 };
83
84 template<class InputIterator, class UnaryFunction, class IndexExpr>
operator <<(meta_kernel & kernel,const transform_iterator_index_expr<InputIterator,UnaryFunction,IndexExpr> & expr)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
transform_iterator(InputIterator iterator,UnaryFunction transform)121 transform_iterator(InputIterator iterator, UnaryFunction transform)
122 : super_type(iterator),
123 m_transform(transform)
124 {
125 }
126
transform_iterator(const transform_iterator<InputIterator,UnaryFunction> & other)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>&
operator =(const transform_iterator<InputIterator,UnaryFunction> & other)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
~transform_iterator()147 ~transform_iterator()
148 {
149 }
150
get_index() const151 size_t get_index() const
152 {
153 return super_type::base().get_index();
154 }
155
get_buffer() const156 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>
operator [](const IndexExpression & expr) const163 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
dereference() const175 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>
make_transform_iterator(InputIterator iterator,UnaryFunction transform)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
228