thrust/iterator/discard_iterator.h

File members: thrust/iterator/discard_iterator.h

/*
 *  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/iterator/counting_iterator.h>
#include <thrust/iterator/detail/any_assign.h>
#include <thrust/iterator/iterator_adaptor.h>

#include <cuda/std/cstddef>

THRUST_NAMESPACE_BEGIN

template <typename>
class discard_iterator;

namespace detail
{
template <typename System>
struct make_discard_iterator_base
{
  // XXX value_type should actually be void but this interferes with zip_iterator<discard_iterator>
  using value_type    = any_assign;
  using reference     = any_assign&;
  using incrementable = ::cuda::std::ptrdiff_t;

  using base_iterator = counting_iterator<incrementable, System, random_access_traversal_tag>;

  using type =
    iterator_adaptor<discard_iterator<System>,
                     base_iterator,
                     value_type,
                     iterator_system_t<base_iterator>,
                     iterator_traversal_t<base_iterator>,
                     reference>;
};
} // namespace detail

_CCCL_DIAG_PUSH
_CCCL_DIAG_SUPPRESS_MSVC(4244 4267) // possible loss of data

template <typename System = use_default>
class discard_iterator : public detail::make_discard_iterator_base<System>::type
{
  friend class iterator_core_access;
  using super_t       = typename detail::make_discard_iterator_base<System>::type;
  using incrementable = typename detail::make_discard_iterator_base<System>::incrementable;
  using base_iterator = typename detail::make_discard_iterator_base<System>::base_iterator;

public:
  using reference  = typename super_t::reference;
  using value_type = typename super_t::value_type;

  _CCCL_HOST_DEVICE discard_iterator(incrementable const& i = incrementable())
      : super_t(base_iterator(i))
  {}

private: // Core iterator interface
  _CCCL_HOST_DEVICE reference dereference() const
  {
    return m_element;
  }

  mutable value_type m_element;

};

inline _CCCL_HOST_DEVICE discard_iterator<>
make_discard_iterator(discard_iterator<>::difference_type i = discard_iterator<>::difference_type(0))
{
  return discard_iterator<>(i);
}

_CCCL_DIAG_POP

THRUST_NAMESPACE_END