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//---------------------------------------------------------------------------//
// Copyright (c) 2013-2014 Kyle Lutz <kyle.r.lutz@gmail.com>
//
// Distributed under the Boost Software License, Version 1.0
// See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt
//
// See http://boostorg.github.com/compute for more information.
//---------------------------------------------------------------------------//
#ifndef BOOST_COMPUTE_ITERATOR_DISCARD_ITERATOR_HPP
#define BOOST_COMPUTE_ITERATOR_DISCARD_ITERATOR_HPP
#include <string>
#include <cstddef>
#include <iterator>
#include <boost/config.hpp>
#include <boost/iterator/iterator_facade.hpp>
#include <boost/compute/detail/meta_kernel.hpp>
#include <boost/compute/type_traits/is_device_iterator.hpp>
namespace boost {
namespace compute {
// forward declaration for discard_iterator
class discard_iterator;
namespace detail {
// helper class which defines the iterator_facade super-class
// type for discard_iterator
struct discard_iterator_base
{
typedef ::boost::iterator_facade<
::boost::compute::discard_iterator,
void,
::std::random_access_iterator_tag,
void *
> type;
};
template<class IndexExpr>
struct discard_iterator_index_expr
{
typedef void result_type;
discard_iterator_index_expr(const IndexExpr &expr)
: m_expr(expr)
{
}
IndexExpr m_expr;
};
template<class IndexExpr>
inline meta_kernel& operator<<(meta_kernel &kernel,
const discard_iterator_index_expr<IndexExpr> &expr)
{
(void) expr;
return kernel;
}
} // end detail namespace
/// \class discard_iterator
/// \brief An iterator which discards all values written to it.
///
/// \see make_discard_iterator(), constant_iterator
class discard_iterator : public detail::discard_iterator_base::type
{
public:
typedef detail::discard_iterator_base::type super_type;
typedef super_type::reference reference;
typedef super_type::difference_type difference_type;
discard_iterator(size_t index = 0)
: m_index(index)
{
}
discard_iterator(const discard_iterator &other)
: m_index(other.m_index)
{
}
discard_iterator& operator=(const discard_iterator &other)
{
if(this != &other){
m_index = other.m_index;
}
return *this;
}
~discard_iterator()
{
}
/// \internal_
template<class Expr>
detail::discard_iterator_index_expr<Expr>
operator[](const Expr &expr) const
{
return detail::discard_iterator_index_expr<Expr>(expr);
}
private:
friend class ::boost::iterator_core_access;
/// \internal_
reference dereference() const
{
return 0;
}
/// \internal_
bool equal(const discard_iterator &other) const
{
return m_index == other.m_index;
}
/// \internal_
void increment()
{
m_index++;
}
/// \internal_
void decrement()
{
m_index--;
}
/// \internal_
void advance(difference_type n)
{
m_index = static_cast<size_t>(static_cast<difference_type>(m_index) + n);
}
/// \internal_
difference_type distance_to(const discard_iterator &other) const
{
return static_cast<difference_type>(other.m_index - m_index);
}
private:
size_t m_index;
};
/// Returns a new discard_iterator with \p index.
///
/// \param index the index of the iterator
///
/// \return a \c discard_iterator at \p index
inline discard_iterator make_discard_iterator(size_t index = 0)
{
return discard_iterator(index);
}
/// internal_ (is_device_iterator specialization for discard_iterator)
template<>
struct is_device_iterator<discard_iterator> : boost::true_type {};
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_ITERATOR_DISCARD_ITERATOR_HPP
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