/*
 *  Copyright 2008-2013 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.
 */

#pragma once

#include <thrust/detail/config.h>

#if defined(_CCCL_IMPLICIT_SYSTEM_HEADER_GCC)
#  pragma GCC system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_CLANG)
#  pragma clang system_header
#elif defined(_CCCL_IMPLICIT_SYSTEM_HEADER_MSVC)
#  pragma system_header
#endif // no system header
#include <thrust/functional.h>
#include <thrust/replace.h>
#include <thrust/system/detail/generic/replace.h>
#include <thrust/transform.h>

THRUST_NAMESPACE_BEGIN
namespace system
{
namespace detail
{
namespace generic
{
namespace detail
{

// this functor receives x, and returns a new_value if predicate(x) is true; otherwise,
// it returns x
template <typename Predicate, typename NewType, typename OutputType>
struct new_value_if
{
  _CCCL_HOST_DEVICE new_value_if(Predicate p, NewType nv)
      : pred(p)
      , new_value(nv)
  {}

  template <typename InputType>
  _CCCL_HOST_DEVICE OutputType operator()(const InputType& x) const
  {
    return pred(x) ? new_value : x;
  } // end operator()()

  // this version of operator()() works like the previous but
  // feeds its second argument to pred
  template <typename InputType, typename PredicateArgumentType>
  _CCCL_HOST_DEVICE OutputType operator()(const InputType& x, const PredicateArgumentType& y)
  {
    return pred(y) ? new_value : x;
  } // end operator()()

  Predicate pred;
  NewType new_value;
}; // end new_value_if

// this unary functor ignores its argument and returns a constant
template <typename T>
struct constant_unary
{
  _CCCL_HOST_DEVICE constant_unary(T _c)
      : c(_c)
  {}

  template <typename U>
  _CCCL_HOST_DEVICE T operator()(U&)
  {
    return c;
  } // end operator()()

  T c;
}; // end constant_unary

} // namespace detail

template <typename DerivedPolicy, typename InputIterator, typename OutputIterator, typename Predicate, typename T>
_CCCL_HOST_DEVICE OutputIterator replace_copy_if(
  thrust::execution_policy<DerivedPolicy>& exec,
  InputIterator first,
  InputIterator last,
  OutputIterator result,
  Predicate pred,
  const T& new_value)
{
  typedef typename thrust::iterator_traits<OutputIterator>::value_type OutputType;

  detail::new_value_if<Predicate, T, OutputType> op(pred, new_value);
  return thrust::transform(exec, first, last, result, op);
} // end replace_copy_if()

template <typename DerivedPolicy,
          typename InputIterator1,
          typename InputIterator2,
          typename OutputIterator,
          typename Predicate,
          typename T>
_CCCL_HOST_DEVICE OutputIterator replace_copy_if(
  thrust::execution_policy<DerivedPolicy>& exec,
  InputIterator1 first,
  InputIterator1 last,
  InputIterator2 stencil,
  OutputIterator result,
  Predicate pred,
  const T& new_value)
{
  typedef typename thrust::iterator_traits<OutputIterator>::value_type OutputType;

  detail::new_value_if<Predicate, T, OutputType> op(pred, new_value);
  return thrust::transform(exec, first, last, stencil, result, op);
} // end replace_copy_if()

template <typename DerivedPolicy, typename InputIterator, typename OutputIterator, typename T>
_CCCL_HOST_DEVICE OutputIterator replace_copy(
  thrust::execution_policy<DerivedPolicy>& exec,
  InputIterator first,
  InputIterator last,
  OutputIterator result,
  const T& old_value,
  const T& new_value)
{
  using thrust::placeholders::_1;

  return thrust::replace_copy_if(exec, first, last, result, _1 == old_value, new_value);
} // end replace_copy()

template <typename DerivedPolicy, typename ForwardIterator, typename Predicate, typename T>
_CCCL_HOST_DEVICE void replace_if(
  thrust::execution_policy<DerivedPolicy>& exec,
  ForwardIterator first,
  ForwardIterator last,
  Predicate pred,
  const T& new_value)
{
  detail::constant_unary<T> f(new_value);
  thrust::transform_if(exec, first, last, first, first, f, pred);
} // end replace_if()

template <typename DerivedPolicy, typename ForwardIterator, typename InputIterator, typename Predicate, typename T>
_CCCL_HOST_DEVICE void replace_if(
  thrust::execution_policy<DerivedPolicy>& exec,
  ForwardIterator first,
  ForwardIterator last,
  InputIterator stencil,
  Predicate pred,
  const T& new_value)
{
  detail::constant_unary<T> f(new_value);
  thrust::transform_if(exec, first, last, stencil, first, f, pred);
} // end replace_if()

template <typename DerivedPolicy, typename ForwardIterator, typename T>
_CCCL_HOST_DEVICE void
replace(thrust::execution_policy<DerivedPolicy>& exec,
        ForwardIterator first,
        ForwardIterator last,
        const T& old_value,
        const T& new_value)
{
  using thrust::placeholders::_1;

  return thrust::replace_if(exec, first, last, _1 == old_value, new_value);
} // end replace()

} // end namespace generic
} // end namespace detail
} // end namespace system
THRUST_NAMESPACE_END
