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//---------------------------------------------------------------------------//
// Copyright (c) 2013 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_COUNTING_ITERATOR_HPP
#define BOOST_COMPUTE_ITERATOR_COUNTING_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 counting_iterator<T>
template<class T> class counting_iterator;
namespace detail {
// helper class which defines the iterator_facade super-class
// type for counting_iterator<T>
template<class T>
class counting_iterator_base
{
public:
typedef ::boost::iterator_facade<
::boost::compute::counting_iterator<T>,
T,
::std::random_access_iterator_tag
> type;
};
template<class T, class IndexExpr>
struct counting_iterator_index_expr
{
typedef T result_type;
counting_iterator_index_expr(const T init, const IndexExpr &expr)
: m_init(init),
m_expr(expr)
{
}
const T m_init;
const IndexExpr m_expr;
};
template<class T, class IndexExpr>
inline meta_kernel& operator<<(meta_kernel &kernel,
const counting_iterator_index_expr<T, IndexExpr> &expr)
{
return kernel << '(' << expr.m_init << '+' << expr.m_expr << ')';
}
} // end detail namespace
/// \class counting_iterator
/// \brief The counting_iterator class implements a counting iterator.
///
/// A counting iterator returns an internal value (initialized with \p init)
/// which is incremented each time the iterator is incremented.
///
/// For example, this could be used to implement the iota() algorithm in terms
/// of the copy() algorithm by copying from a range of counting iterators:
///
/// \snippet test/test_counting_iterator.cpp iota_with_copy
///
/// \see make_counting_iterator()
template<class T>
class counting_iterator : public detail::counting_iterator_base<T>::type
{
public:
typedef typename detail::counting_iterator_base<T>::type super_type;
typedef typename super_type::reference reference;
typedef typename super_type::difference_type difference_type;
counting_iterator(const T &init)
: m_init(init)
{
}
counting_iterator(const counting_iterator<T> &other)
: m_init(other.m_init)
{
}
counting_iterator<T>& operator=(const counting_iterator<T> &other)
{
if(this != &other){
m_init = other.m_init;
}
return *this;
}
~counting_iterator()
{
}
size_t get_index() const
{
return 0;
}
template<class Expr>
detail::counting_iterator_index_expr<T, Expr>
operator[](const Expr &expr) const
{
return detail::counting_iterator_index_expr<T, Expr>(m_init, expr);
}
private:
friend class ::boost::iterator_core_access;
reference dereference() const
{
return m_init;
}
bool equal(const counting_iterator<T> &other) const
{
return m_init == other.m_init;
}
void increment()
{
m_init++;
}
void decrement()
{
m_init--;
}
void advance(difference_type n)
{
m_init += static_cast<T>(n);
}
difference_type distance_to(const counting_iterator<T> &other) const
{
return difference_type(other.m_init) - difference_type(m_init);
}
private:
T m_init;
};
/// Returns a new counting_iterator starting at \p init.
///
/// \param init the initial value
///
/// \return a counting_iterator with \p init.
///
/// For example, to create a counting iterator which returns unsigned integers
/// and increments from one:
/// \code
/// auto iter = make_counting_iterator<uint_>(1);
/// \endcode
template<class T>
inline counting_iterator<T> make_counting_iterator(const T &init)
{
return counting_iterator<T>(init);
}
/// \internal_ (is_device_iterator specialization for counting_iterator)
template<class T>
struct is_device_iterator<counting_iterator<T> > : boost::true_type {};
} // end compute namespace
} // end boost namespace
#endif // BOOST_COMPUTE_ITERATOR_COUNTING_ITERATOR_HPP
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