//---------------------------------------------------------------------------//
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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_ZIP_ITERATOR_HPP
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#define BOOST_COMPUTE_ITERATOR_ZIP_ITERATOR_HPP
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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/fusion/algorithm/iteration/for_each.hpp>
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#include <boost/iterator/iterator_facade.hpp>
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#include <boost/mpl/back_inserter.hpp>
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#include <boost/mpl/transform.hpp>
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#include <boost/mpl/vector.hpp>
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#include <boost/preprocessor/repetition.hpp>
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#include <boost/tuple/tuple.hpp>
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#include <boost/tuple/tuple_comparison.hpp>
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#include <boost/compute/config.hpp>
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#include <boost/compute/functional.hpp>
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#include <boost/compute/detail/meta_kernel.hpp>
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#include <boost/compute/detail/mpl_vector_to_tuple.hpp>
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#include <boost/compute/types/tuple.hpp>
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#include <boost/compute/type_traits/is_device_iterator.hpp>
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#include <boost/compute/type_traits/type_name.hpp>
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namespace boost {
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namespace compute {
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// forward declaration for zip_iterator
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template<class IteratorTuple>
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class zip_iterator;
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namespace detail {
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namespace mpl = boost::mpl;
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// meta-function returning the value_type for an iterator
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template<class Iterator>
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struct make_iterator_value_type
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{
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typedef typename std::iterator_traits<Iterator>::value_type type;
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};
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// meta-function returning the value_type for a zip_iterator
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template<class IteratorTuple>
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struct make_zip_iterator_value_type
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{
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typedef typename
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detail::mpl_vector_to_tuple<
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typename mpl::transform<
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IteratorTuple,
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make_iterator_value_type<mpl::_1>,
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mpl::back_inserter<mpl::vector<> >
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>::type
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>::type type;
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};
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// helper class which defines the iterator_facade super-class
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// type for zip_iterator
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template<class IteratorTuple>
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class zip_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::zip_iterator<IteratorTuple>,
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typename make_zip_iterator_value_type<IteratorTuple>::type,
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::std::random_access_iterator_tag,
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typename make_zip_iterator_value_type<IteratorTuple>::type
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> type;
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};
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template<class IteratorTuple, class IndexExpr>
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struct zip_iterator_index_expr
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{
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typedef typename
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make_zip_iterator_value_type<IteratorTuple>::type
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result_type;
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zip_iterator_index_expr(const IteratorTuple &iterators,
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const IndexExpr &index_expr)
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: m_iterators(iterators),
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m_index_expr(index_expr)
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{
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}
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const IteratorTuple m_iterators;
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const IndexExpr m_index_expr;
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};
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/// \internal_
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#define BOOST_COMPUTE_PRINT_ELEM(z, n, unused) \
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BOOST_PP_EXPR_IF(n, << ", ") \
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<< boost::get<n>(expr.m_iterators)[expr.m_index_expr]
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/// \internal_
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#define BOOST_COMPUTE_PRINT_ZIP_IDX(z, n, unused) \
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template<BOOST_PP_ENUM_PARAMS(n, class Iterator), class IndexExpr> \
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inline meta_kernel& operator<<( \
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meta_kernel &kernel, \
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const zip_iterator_index_expr< \
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boost::tuple<BOOST_PP_ENUM_PARAMS(n, Iterator)>, \
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IndexExpr \
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> &expr) \
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{ \
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typedef typename \
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boost::tuple<BOOST_PP_ENUM_PARAMS(n, Iterator)> \
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tuple_type; \
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typedef typename \
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make_zip_iterator_value_type<tuple_type>::type \
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value_type; \
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kernel.inject_type<value_type>(); \
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return kernel \
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<< "(" << type_name<value_type>() << ")" \
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<< "{ " \
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BOOST_PP_REPEAT(n, BOOST_COMPUTE_PRINT_ELEM, ~) \
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<< "}"; \
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}
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BOOST_PP_REPEAT_FROM_TO(1, BOOST_COMPUTE_MAX_ARITY, BOOST_COMPUTE_PRINT_ZIP_IDX, ~)
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#undef BOOST_COMPUTE_PRINT_ZIP_IDX
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#undef BOOST_COMPUTE_PRINT_ELEM
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struct iterator_advancer
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{
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iterator_advancer(size_t n)
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: m_distance(n)
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{
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}
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template<class Iterator>
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void operator()(Iterator &i) const
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{
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std::advance(i, m_distance);
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}
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size_t m_distance;
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};
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template<class Iterator>
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void increment_iterator(Iterator &i)
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{
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i++;
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}
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template<class Iterator>
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void decrement_iterator(Iterator &i)
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{
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i--;
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}
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} // end detail namespace
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/// \class zip_iterator
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/// \brief A zip iterator adaptor.
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///
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/// The zip_iterator class combines values from multiple input iterators. When
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/// dereferenced it returns a tuple containing each value at the current
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/// position in each input range.
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///
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/// \see make_zip_iterator()
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template<class IteratorTuple>
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class zip_iterator : public detail::zip_iterator_base<IteratorTuple>::type
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{
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public:
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typedef typename
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detail::zip_iterator_base<IteratorTuple>::type
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super_type;
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typedef typename super_type::value_type value_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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typedef IteratorTuple iterator_tuple;
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zip_iterator(IteratorTuple iterators)
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: m_iterators(iterators)
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{
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}
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zip_iterator(const zip_iterator<IteratorTuple> &other)
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: m_iterators(other.m_iterators)
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{
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}
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zip_iterator<IteratorTuple>&
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operator=(const zip_iterator<IteratorTuple> &other)
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{
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if(this != &other){
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super_type::operator=(other);
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m_iterators = other.m_iterators;
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}
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return *this;
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}
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~zip_iterator()
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{
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}
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const IteratorTuple& get_iterator_tuple() const
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{
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return m_iterators;
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}
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template<class IndexExpression>
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detail::zip_iterator_index_expr<IteratorTuple, IndexExpression>
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operator[](const IndexExpression &expr) const
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{
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return detail::zip_iterator_index_expr<IteratorTuple,
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IndexExpression>(m_iterators,
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expr);
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}
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private:
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friend class ::boost::iterator_core_access;
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reference dereference() const
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{
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return reference();
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}
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bool equal(const zip_iterator<IteratorTuple> &other) const
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{
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return m_iterators == other.m_iterators;
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}
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void increment()
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{
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boost::fusion::for_each(m_iterators, detail::increment_iterator);
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}
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void decrement()
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{
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boost::fusion::for_each(m_iterators, detail::decrement_iterator);
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}
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void advance(difference_type n)
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{
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boost::fusion::for_each(m_iterators, detail::iterator_advancer(n));
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}
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difference_type distance_to(const zip_iterator<IteratorTuple> &other) const
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{
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return std::distance(boost::get<0>(m_iterators),
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boost::get<0>(other.m_iterators));
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}
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private:
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IteratorTuple m_iterators;
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};
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/// Creates a zip_iterator for \p iterators.
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///
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/// \param iterators a tuple of input iterators to zip together
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///
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/// \return a \c zip_iterator for \p iterators
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///
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/// For example, to zip together iterators from three vectors (\c a, \c b, and
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/// \p c):
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/// \code
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/// auto zipped = boost::compute::make_zip_iterator(
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/// boost::make_tuple(a.begin(), b.begin(), c.begin())
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/// );
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/// \endcode
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template<class IteratorTuple>
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inline zip_iterator<IteratorTuple>
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make_zip_iterator(IteratorTuple iterators)
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{
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return zip_iterator<IteratorTuple>(iterators);
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}
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/// \internal_ (is_device_iterator specialization for zip_iterator)
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template<class IteratorTuple>
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struct is_device_iterator<zip_iterator<IteratorTuple> > : boost::true_type {};
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namespace detail {
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// get<N>() specialization for zip_iterator
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/// \internal_
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#define BOOST_COMPUTE_ZIP_GET_N(z, n, unused) \
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template<size_t N, class IteratorTuple, class IndexExpr, \
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BOOST_PP_ENUM_PARAMS(n, class T)> \
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inline meta_kernel& \
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operator<<(meta_kernel &kernel, \
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const invoked_get< \
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N, \
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zip_iterator_index_expr<IteratorTuple, IndexExpr>, \
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boost::tuple<BOOST_PP_ENUM_PARAMS(n, T)> \
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> &expr) \
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{ \
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typedef typename boost::tuple<BOOST_PP_ENUM_PARAMS(n, T)> Tuple; \
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typedef typename boost::tuples::element<N, Tuple>::type T; \
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BOOST_STATIC_ASSERT(N < size_t(boost::tuples::length<Tuple>::value)); \
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kernel.inject_type<T>(); \
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return kernel \
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<< boost::get<N>(expr.m_arg.m_iterators)[expr.m_arg.m_index_expr]; \
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}
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BOOST_PP_REPEAT_FROM_TO(1, BOOST_COMPUTE_MAX_ARITY, BOOST_COMPUTE_ZIP_GET_N, ~)
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#undef BOOST_COMPUTE_ZIP_GET_N
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} // end detail namespace
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} // end compute namespace
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} // end boost namespace
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#endif // BOOST_COMPUTE_ITERATOR_ZIP_ITERATOR_HPP
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