/*
 *  Copyright 2008-2010 NVIDIA Corporation
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */


/*! \file adjacent_difference.h
 *  \brief Compute difference between consecutive elements of a sequence.
 */

#pragma once

#include <thrust/detail/config.h>

namespace thrust
{

/*! \addtogroup transformations Transformations
 *  \{
 */

/*! \p adjacent_difference calculates the differences of adjacent elements in the
 *  range <tt>[first, last)</tt>. That is, <tt>*first</tt> is assigned to
 *  <tt>*result</tt>, and, for each iterator \p i in the range
 *  <tt>[first + 1, last)</tt>, the difference of <tt>*i</tt> and <tt>*(i - 1)</tt>
 *  is assigned to <tt>*(result + (i - first))</tt>.
 *
 *  This version of \p adjacent_difference uses <tt>operator-</tt> to calculate
 *  differences.
 *
 *  \param first The beginning of the input range.
 *  \param last  The end of the input range.
 *  \param result The beginning of the output range.
 *  \return The iterator <tt>result + (last - first)</tt>
 *
 *  \tparam InputIterator is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
 *          and \c x and \c y are objects of \p InputIterator's \c value_type, then \c x - \c is defined,
 *          and \p InputIterator's \c value_type is convertible to a type in \p OutputIterator's set of \c value_types,
 *          and the return type of <tt>x - y</tt> is convertible to a type in \p OutputIterator's set of \c value_types.
 *  \tparam OutputIterator is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a>.
 *
 *  \see http://www.sgi.com/tech/stl/adjacent_difference.html
 *  \see inclusive_scan
 *
 *  \note Note that \p result is permitted to be the same iterator as \p first. This is
 *        useful for computing differences "in place".
 */
template <typename InputIterator, typename OutputIterator>
OutputIterator adjacent_difference(InputIterator first, InputIterator last, 
                                   OutputIterator result);

/*! \p adjacent_difference calculates the differences of adjacent elements in the
 *  range <tt>[first, last)</tt>. That is, <tt>*first</tt> is assigned to
 *  <tt>*result</tt>, and, for each iterator \p i in the range
 *  <tt>[first + 1, last)</tt>, <tt>binary_op(*i, *(i - 1))</tt> is assigned to
 *  <tt>*(result + (i - first))</tt>.
 *
 *  This version of \p adjacent_difference uses the binary function \p binary_op to
 *  calculate differences.
 *
 *  \param first The beginning of the input range.
 *  \param last  The end of the input range.
 *  \param result The beginning of the output range.
 *  \param binary_op The binary function used to compute differences.
 *  \return The iterator <tt>result + (last - first)</tt>
 *
 *  \tparam InputIterator is a model of <a href="http://www.sgi.com/tech/stl/InputIterator.html">Input Iterator</a>,
 *          and \p InputIterator's \c value_type is convertible to \p BinaryFunction's \c first_argument_type and \c second_argument_type,
 *          and \p InputIterator's \c value_type is convertible to a type in \p OutputIterator's set of \c value_types.
 *  \tparam OutputIterator is a model of <a href="http://www.sgi.com/tech/stl/OutputIterator.html">Output Iterator</a>.
 *  \tparam BinaryFunction's \c result_type is convertible to a type in \p OutputIterator's set of \c value_types.
 *
 *  \see http://www.sgi.com/tech/stl/adjacent_difference.html
 *  \see inclusive_scan
 *
 *  \note Note that \p result is permitted to be the same iterator as \p first. This is
 *        useful for computing differences "in place".
 */
template <typename InputIterator, typename OutputIterator, typename BinaryFunction>
OutputIterator adjacent_difference(InputIterator first, InputIterator last,
                                   OutputIterator result,
                                   BinaryFunction binary_op);

/*! \}
 */

} // end namespace thrust

#include <thrust/detail/adjacent_difference.inl>