172 lines
4.3 KiB
Plaintext
172 lines
4.3 KiB
Plaintext
//---------------------------------------------------------------------------//
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// Copyright (c) 2013 Kyle Lutz <kyle.r.lutz@gmail.com>
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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// See http://boostorg.github.com/compute for more information.
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//---------------------------------------------------------------------------//
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#ifndef BOOST_COMPUTE_ITERATOR_CONSTANT_ITERATOR_HPP
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#define BOOST_COMPUTE_ITERATOR_CONSTANT_ITERATOR_HPP
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#include <string>
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#include <cstddef>
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#include <iterator>
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#include <boost/config.hpp>
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#include <boost/iterator/iterator_facade.hpp>
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#include <boost/compute/detail/meta_kernel.hpp>
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#include <boost/compute/type_traits/is_device_iterator.hpp>
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namespace boost {
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namespace compute {
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// forward declaration for constant_iterator<T>
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template<class T> class constant_iterator;
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namespace detail {
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// helper class which defines the iterator_facade super-class
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// type for constant_iterator<T>
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template<class T>
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class constant_iterator_base
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{
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public:
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typedef ::boost::iterator_facade<
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::boost::compute::constant_iterator<T>,
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T,
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::std::random_access_iterator_tag
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> type;
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};
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} // end detail namespace
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/// \class constant_iterator
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/// \brief An iterator with a constant value.
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///
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/// The constant_iterator class provides an iterator which returns a constant
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/// value when dereferenced.
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///
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/// For example, this could be used to implement the fill() algorithm in terms
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/// of the copy() algorithm by copying from a range of constant iterators:
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///
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/// \snippet test/test_constant_iterator.cpp fill_with_copy
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///
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/// \see make_constant_iterator()
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template<class T>
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class constant_iterator : public detail::constant_iterator_base<T>::type
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{
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public:
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typedef typename detail::constant_iterator_base<T>::type super_type;
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typedef typename super_type::reference reference;
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typedef typename super_type::difference_type difference_type;
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constant_iterator(const T &value, size_t index = 0)
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: m_value(value),
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m_index(index)
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{
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}
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constant_iterator(const constant_iterator<T> &other)
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: m_value(other.m_value),
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m_index(other.m_index)
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{
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}
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constant_iterator<T>& operator=(const constant_iterator<T> &other)
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{
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if(this != &other){
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m_value = other.m_value;
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m_index = other.m_index;
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}
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return *this;
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}
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~constant_iterator()
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{
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}
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size_t get_index() const
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{
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return m_index;
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}
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/// \internal_
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template<class Expr>
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detail::meta_kernel_literal<T> operator[](const Expr &expr) const
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{
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(void) expr;
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return detail::meta_kernel::make_lit<T>(m_value);
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}
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private:
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friend class ::boost::iterator_core_access;
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/// \internal_
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reference dereference() const
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{
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return m_value;
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}
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/// \internal_
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bool equal(const constant_iterator<T> &other) const
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{
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return m_value == other.m_value && m_index == other.m_index;
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}
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/// \internal_
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void increment()
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{
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m_index++;
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}
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/// \internal_
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void decrement()
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{
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m_index--;
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}
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/// \internal_
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void advance(difference_type n)
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{
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m_index = static_cast<size_t>(static_cast<difference_type>(m_index) + n);
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}
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/// \internal_
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difference_type distance_to(const constant_iterator<T> &other) const
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{
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return static_cast<difference_type>(other.m_index - m_index);
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}
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private:
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T m_value;
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size_t m_index;
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};
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/// Returns a new constant_iterator with \p value at \p index.
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///
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/// \param value the constant value
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/// \param index the iterators index
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///
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/// \return a \c constant_iterator with \p value
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template<class T>
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inline constant_iterator<T>
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make_constant_iterator(const T &value, size_t index = 0)
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{
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return constant_iterator<T>(value, index);
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}
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/// \internal_ (is_device_iterator specialization for constant_iterator)
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template<class T>
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struct is_device_iterator<constant_iterator<T> > : boost::true_type {};
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_ITERATOR_CONSTANT_ITERATOR_HPP
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