171 lines
4.0 KiB
Plaintext
171 lines
4.0 KiB
Plaintext
//---------------------------------------------------------------------------//
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// Copyright (c) 2013-2014 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_DISCARD_ITERATOR_HPP
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#define BOOST_COMPUTE_ITERATOR_DISCARD_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 discard_iterator
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class discard_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 discard_iterator
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struct discard_iterator_base
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{
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typedef ::boost::iterator_facade<
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::boost::compute::discard_iterator,
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void,
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::std::random_access_iterator_tag,
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void *
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> type;
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};
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template<class IndexExpr>
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struct discard_iterator_index_expr
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{
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typedef void result_type;
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discard_iterator_index_expr(const IndexExpr &expr)
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: m_expr(expr)
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{
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}
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IndexExpr m_expr;
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};
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template<class IndexExpr>
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inline meta_kernel& operator<<(meta_kernel &kernel,
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const discard_iterator_index_expr<IndexExpr> &expr)
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{
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(void) expr;
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return kernel;
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}
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} // end detail namespace
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/// \class discard_iterator
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/// \brief An iterator which discards all values written to it.
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///
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/// \see make_discard_iterator(), constant_iterator
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class discard_iterator : public detail::discard_iterator_base::type
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{
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public:
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typedef detail::discard_iterator_base::type super_type;
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typedef super_type::reference reference;
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typedef super_type::difference_type difference_type;
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discard_iterator(size_t index = 0)
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: m_index(index)
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{
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}
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discard_iterator(const discard_iterator &other)
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: m_index(other.m_index)
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{
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}
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discard_iterator& operator=(const discard_iterator &other)
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{
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if(this != &other){
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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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~discard_iterator()
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{
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}
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/// \internal_
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template<class Expr>
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detail::discard_iterator_index_expr<Expr>
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operator[](const Expr &expr) const
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{
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return detail::discard_iterator_index_expr<Expr>(expr);
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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 0;
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}
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/// \internal_
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bool equal(const discard_iterator &other) const
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{
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return 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 discard_iterator &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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size_t m_index;
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};
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/// Returns a new discard_iterator with \p index.
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///
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/// \param index the index of the iterator
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///
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/// \return a \c discard_iterator at \p index
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inline discard_iterator make_discard_iterator(size_t index = 0)
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{
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return discard_iterator(index);
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}
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/// internal_ (is_device_iterator specialization for discard_iterator)
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template<>
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struct is_device_iterator<discard_iterator> : 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_DISCARD_ITERATOR_HPP
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