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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;
+ 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