//---------------------------------------------------------------------------//
// 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_ALGORITHM_COPY_IF_HPP
#define BOOST_COMPUTE_ALGORITHM_COPY_IF_HPP

#include <boost/compute/algorithm/transform_if.hpp>
#include <boost/compute/functional/identity.hpp>

namespace boost {
namespace compute {
namespace detail {

// like the copy_if() algorithm but writes the indices of the values for which
// predicate returns true.
template<class InputIterator, class OutputIterator, class Predicate>
inline OutputIterator copy_index_if(InputIterator first,
                                    InputIterator last,
                                    OutputIterator result,
                                    Predicate predicate,
                                    command_queue &queue = system::default_queue())
{
    typedef typename std::iterator_traits<InputIterator>::value_type T;

    return detail::transform_if_impl(
        first, last, result, identity<T>(), predicate, true, queue
    );
}

} // end detail namespace

/// Copies each element in the range [\p first, \p last) for which
/// \p predicate returns \c true to the range beginning at \p result.
///
/// Space complexity: \Omega(2n)
template<class InputIterator, class OutputIterator, class Predicate>
inline OutputIterator copy_if(InputIterator first,
                              InputIterator last,
                              OutputIterator result,
                              Predicate predicate,
                              command_queue &queue = system::default_queue())
{
    typedef typename std::iterator_traits<InputIterator>::value_type T;

    return ::boost::compute::transform_if(
        first, last, result, identity<T>(), predicate, queue
    );
}

} // end compute namespace
} // end boost namespace

#endif // BOOST_COMPUTE_ALGORITHM_COPY_IF_HPP