otbZipIterator.h

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/*
 * Copyright (C) 2005-2022 Centre National d'Etudes Spatiales (CNES)
 *
 * This file is part of Orfeo Toolbox
 *
 *     https://www.orfeo-toolbox.org/
 *
 * 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.
 */
 
#ifndef otbZipIterator_h
#define otbZipIterator_h
 
#include "otbIteratorHelpers.h"
#include "otbSpan.h"
#include "itkMacro.h"
#include <type_traits>
#include <vector>
#include <cassert>
 
namespace otb
{
namespace internals
{
 
template <typename TImageIterator, typename ConstOrMutable>
class ZipIterator
{
public:
 
 
  using ImageIteratorType     = TImageIterator;
 
  using ImageType             = typename TImageIterator::ImageType;
 
  static constexpr unsigned int ImageIteratorDimension = ImageIteratorType::ImageIteratorDimension;
 
  using Self                  = ZipIterator;
 
  itkTypeMacroNoParent(ZipIterator);
 
  using IndexType             = typename ImageIteratorType::IndexType;
 
  using SizeType              = typename ImageIteratorType::SizeType;
 
  using OffsetType            = typename ImageIteratorType::OffsetType;
 
  using RegionType            = typename ImageIteratorType::RegionType;
 
  using PixelContainer        = typename ImageIteratorType::PixelContainer;
  using PixelContainerPointer = typename PixelContainer::Pointer;
 
  using InternalPixelType     = typename ImageIteratorType::InternalPixelType;
 
  using PixelType             = typename ImageIteratorType::PixelType;
 
  using AccessorType          = typename ImageIteratorType::AccessorType;
  using AccessorFunctorType   = typename ImageIteratorType::AccessorFunctorType;
 
  ZipIterator           ()                   = default;
  ~ZipIterator          ()                   = default;
  ZipIterator           (ZipIterator const&) = default;
  ZipIterator           (ZipIterator     &&) = default;
  ZipIterator& operator=(ZipIterator const&) = default;
  ZipIterator& operator=(ZipIterator     &&) = default;
 
  template <bool IsConst_ = std::is_same<ConstOrMutable, ConstTag>::value, class = std::enable_if<IsConst_>>
  ZipIterator(ZipIterator<ImageIteratorType, MutableTag> const& rhs)
    : m_iterators(rhs.m_iterators())
    {}
 
  template <bool IsConst_ = std::is_same<ConstOrMutable, ConstTag>::value, class = std::enable_if<IsConst_>>
  ZipIterator(ZipIterator<ImageIteratorType, MutableTag> && rhs)
    : m_iterators(move(rhs.m_iterators()))
    {}
 
  ZipIterator(Span<ImageType * const> images, RegionType const& region)
  {
    assert(! images.empty());
    m_iterators.reserve(images.size());
 
    for (auto & im: images)
      m_iterators.emplace_back(im, region);
  }
 
  // static_assert(std::is_copy_constructible<Self>::value, "Requires copy construction");
  // static_assert(std::is_trivially_copy_constructible<Self>::value, "Requires trivial copy construction");
 
  friend bool operator==(ZipIterator const& lhs, ZipIterator const& rhs)
  {
    assert(!lhs.m_iterators.empty());
    assert(lhs.m_iterators.size() == rhs.m_iterators.size());
 
    return lhs.m_iterators.front() == rhs.m_iterators.front();
  }
  friend bool operator!=(ZipIterator const& lhs, ZipIterator const& rhs)
  { return ! (lhs == rhs); }
 
  friend bool operator<=(ZipIterator const& lhs, ZipIterator const& rhs)
  {
    assert(!lhs.m_iterators.empty());
    assert(lhs.m_iterators.size() == rhs.m_iterators.size());
 
    return lhs.m_iterators.front() <= rhs.m_iterators.front();
  }
  friend bool operator<(ZipIterator const& lhs, ZipIterator const& rhs)
  {
    assert(!lhs.m_iterators.empty());
    assert(lhs.m_iterators.size() == rhs.m_iterators.size());
 
    return lhs.m_iterators.front() < rhs.m_iterators.front();
  }
  friend bool operator>=(ZipIterator const& lhs, ZipIterator const& rhs)
  { return ! (lhs < rhs); }
  friend bool operator>(ZipIterator const& lhs, ZipIterator const& rhs)
  { return ! (lhs <= rhs); }
 
  // What about GetIndex() and SetIndex ?
 
  auto const& GetRegion() const
  {
    assert(!m_iterators.empty());
    return m_iterators.front().GetRegion();
  }
 
  void SetRegion(RegionType const& region)
  {
    for (auto & it : m_iterators)
      it.SetRegion(region);
  }
 
  Self& GoToBegin() {
    for (auto & it : m_iterators)
      it.GoToBegin();
    return *this;
  }
 
  Self& GoToEnd() {
    for (auto & it : m_iterators)
      it.GoToEnd();
    return *this;
  }
 
  bool IsAtBegin() const {
    assert(!m_iterators.empty());
    return m_iterators.front().IsAtBegin();
  }
 
  bool IsAtEnd() const {
    assert(!m_iterators.empty());
    return m_iterators.front().IsAtEnd();
  }
 
  Self& operator++() {
    assert(!IsAtEnd());
    for (auto & it : m_iterators)
      ++it;
    return *this;
  }
 
  Self operator++(int) = delete;
 
  using ImageIteratorList_t = std::vector<ImageIteratorType>;
 
  struct PixelListProxy
  {
 
    explicit PixelListProxy(ImageIteratorList_t const& iterators) noexcept
      : m_iterators(iterators)
      {}
    bool empty()   const noexcept {return m_iterators.empty();}
    auto size()    const noexcept {return m_iterators.size();}
 
    struct iterator__
    {
      using difference_type   = typename ImageIteratorList_t::difference_type;
      using value_type        = decltype(typename ImageIteratorList_t::const_iterator{}->Get());
      using pointer           = value_type*;
      using reference         = value_type&;
      using iterator_category = std::forward_iterator_tag;
 
      explicit iterator__(typename ImageIteratorList_t::const_iterator ref)
        : reference_to_value(ref){}
      friend bool operator==(iterator__ const& lhs, iterator__ const& rhs) noexcept
      { return lhs.reference_to_value == rhs.reference_to_value;}
      friend bool operator!=(iterator__ const& lhs, iterator__ const& rhs) noexcept
      { return ! (lhs == rhs);}
      iterator__ & operator++() noexcept {
        ++reference_to_value;
        return *this;
      }
      iterator__ & operator--() noexcept {
        --reference_to_value;
        return *this;
      }
      iterator__ operator+(std::ptrdiff_t offset) const noexcept{
        return iterator__{reference_to_value + offset};
      }
      iterator__ operator-(std::ptrdiff_t offset) const noexcept{
        return iterator__{reference_to_value - offset};
      }
      decltype(auto) operator*() const {
        return reference_to_value->Get();
      }
 
    private:
      typename ImageIteratorList_t::const_iterator reference_to_value;
    };
 
    auto begin()         noexcept { return iterator__(m_iterators.begin()); }
    auto end()           noexcept { return iterator__{m_iterators.end()}; }
    auto begin()   const noexcept { return iterator__{m_iterators.begin()}; }
    auto end()     const noexcept { return iterator__{m_iterators.end()}; }
    auto cbegin()  const noexcept { return iterator__{m_iterators.cbegin()}; }
    auto cend()    const noexcept { return iterator__{m_iterators.cend()}; }
 
    decltype(auto) operator[](std::size_t idx) const {
      assert(idx < size());
      return m_iterators[idx].Get();
    }
    decltype(auto) operator[](std::size_t idx)       {
      assert(idx < size());
      return m_iterators[idx].Get();
    }
 
    decltype(auto) front() const {
      assert(!empty());
      return m_iterators.front().Get();
    }
    decltype(auto) front()       {
      assert(!empty());
      return m_iterators.front().Get();
    }
    decltype(auto) back() const {
      assert(!empty());
      return m_iterators.back().Get();
    }
    decltype(auto) back()       {
      assert(!empty());
      return m_iterators.back().Get();
    }
  private:
    ImageIteratorList_t const& m_iterators;
  };
 
  PixelListProxy Get() const {
    return PixelListProxy{m_iterators};
  }
 
 
  template <typename MultiCompPixelType>
  void Set(MultiCompPixelType const& p)
  {
    assert(p.size() == m_iterators.size());
    for (std::size_t i = 0; i!=m_iterators.size(); ++i)
    {
      m_iterators[i].Set(p[i]);
    }
  }
  // PixelType & Value(); -- cannot be defined and still preserve direct access
  // to memory => we don't provide it.
 
  // ImageType * GetImages();
 
 
  Self& NextLine() {
    for (auto & it : m_iterators)
      it.NextLine();
    return *this;
  }
 
  Self& GoToBeginOfLine() {
    for (auto & it : m_iterators)
      it.GoToBeginOfLine();
    return *this;
  }
 
  Self& GoToEndOfLine() {
    for (auto & it : m_iterators)
      it.GoToEndOfLine();
    return *this;
  }
 
  bool IsAtEndOfLine() const {
    assert(!m_iterators.empty());
    // Const qualifier has been added to ScanLineIterator::IsAtEndOfLine in ITK
    // 5.1 => Use const_cast in the mean time...
    return const_cast<typename ImageIteratorList_t::value_type &>(m_iterators.front()).IsAtEndOfLine();
  }
 
 
private:
  ImageIteratorList_t m_iterators;
};
 
} // otb::internal namespace
 
template <typename TImageIterator>
using ZipIterator      = internals::ZipIterator<TImageIterator, internals::MutableTag>;
 
template <typename TImageIterator>
using ZipConstIterator = internals::ZipIterator<TImageIterator, internals::ConstTag>;
 
} // otb namespace
 
#endif  // otbZipIterator_h