// -*- C++ -*-
//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _PSTL_GLUE_NUMERIC_IMPL_H
#define _PSTL_GLUE_NUMERIC_IMPL_H

#include <__config>
#include <functional>

#include "execution_impl.h"
#include "numeric_fwd.h"
#include "utils.h"

namespace std {

// [exclusive.scan]

template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> exclusive_scan(
    _ExecutionPolicy&& __exec,
    _ForwardIterator1 __first,
    _ForwardIterator1 __last,
    _ForwardIterator2 __result,
    _Tp __init) {
  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);

  using namespace __pstl;
  return __internal::__pattern_transform_scan(
      __dispatch_tag,
      std::forward<_ExecutionPolicy>(__exec),
      __first,
      __last,
      __result,
      __pstl::__internal::__no_op(),
      __init,
      std::plus<_Tp>(),
      /*inclusive=*/std::false_type());
}

template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp, class _BinaryOperation>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> exclusive_scan(
    _ExecutionPolicy&& __exec,
    _ForwardIterator1 __first,
    _ForwardIterator1 __last,
    _ForwardIterator2 __result,
    _Tp __init,
    _BinaryOperation __binary_op) {
  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);

  using namespace __pstl;
  return __internal::__pattern_transform_scan(
      __dispatch_tag,
      std::forward<_ExecutionPolicy>(__exec),
      __first,
      __last,
      __result,
      __pstl::__internal::__no_op(),
      __init,
      __binary_op,
      /*inclusive=*/std::false_type());
}

// [inclusive.scan]

template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
    _ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __result) {
  typedef typename iterator_traits<_ForwardIterator1>::value_type _InputType;
  return transform_inclusive_scan(
      std::forward<_ExecutionPolicy>(__exec),
      __first,
      __last,
      __result,
      std::plus<_InputType>(),
      __pstl::__internal::__no_op());
}

template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryOperation>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
    _ExecutionPolicy&& __exec,
    _ForwardIterator1 __first,
    _ForwardIterator1 __last,
    _ForwardIterator2 __result,
    _BinaryOperation __binary_op) {
  return transform_inclusive_scan(
      std::forward<_ExecutionPolicy>(__exec), __first, __last, __result, __binary_op, __pstl::__internal::__no_op());
}

template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _Tp, class _BinaryOperation>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> inclusive_scan(
    _ExecutionPolicy&& __exec,
    _ForwardIterator1 __first,
    _ForwardIterator1 __last,
    _ForwardIterator2 __result,
    _BinaryOperation __binary_op,
    _Tp __init) {
  return transform_inclusive_scan(
      std::forward<_ExecutionPolicy>(__exec),
      __first,
      __last,
      __result,
      __binary_op,
      __pstl::__internal::__no_op(),
      __init);
}

// [transform.exclusive.scan]

template <class _ExecutionPolicy,
          class _ForwardIterator1,
          class _ForwardIterator2,
          class _Tp,
          class _BinaryOperation,
          class _UnaryOperation>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_exclusive_scan(
    _ExecutionPolicy&& __exec,
    _ForwardIterator1 __first,
    _ForwardIterator1 __last,
    _ForwardIterator2 __result,
    _Tp __init,
    _BinaryOperation __binary_op,
    _UnaryOperation __unary_op) {
  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);

  return __pstl::__internal::__pattern_transform_scan(
      __dispatch_tag,
      std::forward<_ExecutionPolicy>(__exec),
      __first,
      __last,
      __result,
      __unary_op,
      __init,
      __binary_op,
      /*inclusive=*/std::false_type());
}

// [transform.inclusive.scan]

template <class _ExecutionPolicy,
          class _ForwardIterator1,
          class _ForwardIterator2,
          class _BinaryOperation,
          class _UnaryOperation,
          class _Tp>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_inclusive_scan(
    _ExecutionPolicy&& __exec,
    _ForwardIterator1 __first,
    _ForwardIterator1 __last,
    _ForwardIterator2 __result,
    _BinaryOperation __binary_op,
    _UnaryOperation __unary_op,
    _Tp __init) {
  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __result);

  return __pstl::__internal::__pattern_transform_scan(
      __dispatch_tag,
      std::forward<_ExecutionPolicy>(__exec),
      __first,
      __last,
      __result,
      __unary_op,
      __init,
      __binary_op,
      /*inclusive=*/std::true_type());
}

template <class _ExecutionPolicy,
          class _ForwardIterator1,
          class _ForwardIterator2,
          class _UnaryOperation,
          class _BinaryOperation>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> transform_inclusive_scan(
    _ExecutionPolicy&& __exec,
    _ForwardIterator1 __first,
    _ForwardIterator1 __last,
    _ForwardIterator2 __result,
    _BinaryOperation __binary_op,
    _UnaryOperation __unary_op) {
  if (__first != __last) {
    auto __tmp = __unary_op(*__first);
    *__result  = __tmp;
    return transform_inclusive_scan(
        std::forward<_ExecutionPolicy>(__exec), ++__first, __last, ++__result, __binary_op, __unary_op, __tmp);
  } else {
    return __result;
  }
}

// [adjacent.difference]

template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2, class _BinaryOperation>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> adjacent_difference(
    _ExecutionPolicy&& __exec,
    _ForwardIterator1 __first,
    _ForwardIterator1 __last,
    _ForwardIterator2 __d_first,
    _BinaryOperation __op) {
  if (__first == __last)
    return __d_first;

  auto __dispatch_tag = __pstl::__internal::__select_backend(__exec, __first, __d_first);

  return __pstl::__internal::__pattern_adjacent_difference(
      __dispatch_tag, std::forward<_ExecutionPolicy>(__exec), __first, __last, __d_first, __op);
}

template <class _ExecutionPolicy, class _ForwardIterator1, class _ForwardIterator2>
__pstl::__internal::__enable_if_execution_policy<_ExecutionPolicy, _ForwardIterator2> adjacent_difference(
    _ExecutionPolicy&& __exec, _ForwardIterator1 __first, _ForwardIterator1 __last, _ForwardIterator2 __d_first) {
  typedef typename iterator_traits<_ForwardIterator1>::value_type _ValueType;
  return adjacent_difference(
      std::forward<_ExecutionPolicy>(__exec), __first, __last, __d_first, std::minus<_ValueType>());
}

} // namespace std

#endif /* _PSTL_GLUE_NUMERIC_IMPL_H_ */