boost/multi_array/view.hpp

// Copyright 2002 The Trustees of Indiana University.

// Use, modification and distribution is subject to the Boost Software
// License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)

//  Boost.MultiArray Library
//  Authors: Ronald Garcia
//           Jeremy Siek
//           Andrew Lumsdaine
//  See http://www.boost.org/libs/multi_array for documentation.

#ifndef BOOST_MULTI_ARRAY_VIEW_HPP
#define BOOST_MULTI_ARRAY_VIEW_HPP

//
// view.hpp - code for creating "views" of array data.
//

#include "boost/multi_array/base.hpp"
#include "boost/multi_array/concept_checks.hpp"
#include "boost/multi_array/iterator.hpp"
#include "boost/multi_array/storage_order.hpp"
#include "boost/multi_array/subarray.hpp"
#include "boost/multi_array/algorithm.hpp"
#include "boost/type_traits/is_integral.hpp"
#include "boost/utility/enable_if.hpp"
#include "boost/array.hpp"
#include "boost/limits.hpp"
#include <algorithm>
#include <cstddef>
#include <functional>
#include <numeric>

namespace boost {
namespace detail {
namespace multi_array {

// TPtr = const T* defaulted in base.hpp
template <typename T, std::size_t NumDims, typename TPtr>
class const_multi_array_view :
    public boost::detail::multi_array::multi_array_impl_base<T,NumDims>
{
  typedef boost::detail::multi_array::multi_array_impl_base<T,NumDims> super_type;
public:
  typedef typename super_type::value_type value_type;
  typedef typename super_type::const_reference const_reference;
  typedef typename super_type::const_iterator const_iterator;
  typedef typename super_type::const_reverse_iterator const_reverse_iterator;
  typedef typename super_type::element element;
  typedef typename super_type::size_type size_type;
  typedef typename super_type::difference_type difference_type;
  typedef typename super_type::index index;
  typedef typename super_type::extent_range extent_range;

  // template typedefs
  template <std::size_t NDims>
  struct const_array_view {
    typedef boost::detail::multi_array::const_multi_array_view<T,NDims> type;
  };

  template <std::size_t NDims>
  struct array_view {
    typedef boost::detail::multi_array::multi_array_view<T,NDims> type;
  };

  template <typename OPtr>
  const_multi_array_view(const
                         const_multi_array_view<T,NumDims,OPtr>& other) :
    base_(other.base_), origin_offset_(other.origin_offset_),
    num_elements_(other.num_elements_), extent_list_(other.extent_list_),
    stride_list_(other.stride_list_), index_base_list_(other.index_base_list_)
  { }


  template <class BaseList>
#ifdef BOOST_NO_SFINAE
  void
#else
  typename
  disable_if<typename boost::is_integral<BaseList>::type,void >::type
#endif
  reindex(const BaseList& values) {
    boost::function_requires<
      CollectionConcept<BaseList> >();
    boost::detail::multi_array::
      copy_n(values.begin(),num_dimensions(),index_base_list_.begin());
    origin_offset_ =
      this->calculate_indexing_offset(stride_list_,index_base_list_);
  }

  void reindex(index value) {
    index_base_list_.assign(value);
    origin_offset_ =
      this->calculate_indexing_offset(stride_list_,index_base_list_);
  }

  size_type num_dimensions() const { return NumDims; }

  size_type size() const { return extent_list_.front(); }
  size_type max_size() const { return num_elements(); }
  bool empty() const { return size() == 0; }

  const size_type* shape() const {
    return extent_list_.data();
  }

  const index* strides() const {
    return stride_list_.data();
  }

  const T* origin() const { return base_+origin_offset_; }

  size_type num_elements() const { return num_elements_; }

  const index* index_bases() const {
    return index_base_list_.data();
  }

  template <typename IndexList>
  const element& operator()(IndexList indices) const {
    boost::function_requires<
      CollectionConcept<IndexList> >();
    return super_type::access_element(boost::type<const element&>(),
                                      indices,origin(),
                                      shape(),strides(),index_bases());
  }

  // Only allow const element access
  const_reference operator[](index idx) const {
    return super_type::access(boost::type<const_reference>(),
                              idx,origin(),
                              shape(),strides(),
                              index_bases());
  }

  // see generate_array_view in base.hpp
  template <int NDims>
  typename const_array_view<NDims>::type
  operator[](const boost::detail::multi_array::
             index_gen<NumDims,NDims>& indices)
    const {
    typedef typename const_array_view<NDims>::type return_type;
    return
      super_type::generate_array_view(boost::type<return_type>(),
                                      indices,
                                      shape(),
                                      strides(),
                                      index_bases(),
                                      origin());
  }
  const_iterator begin() const {
    return const_iterator(*index_bases(),origin(),
                          shape(),strides(),index_bases());
  }

  const_iterator end() const {
    return const_iterator(*index_bases()+(index)*shape(),origin(),
                          shape(),strides(),index_bases());
  }

  const_reverse_iterator rbegin() const {
    return const_reverse_iterator(end());
  }

  const_reverse_iterator rend() const {
    return const_reverse_iterator(begin());
  }


  template <typename OPtr>
  bool operator==(const
                  const_multi_array_view<T,NumDims,OPtr>& rhs)
    const {
    if(std::equal(extent_list_.begin(),
                  extent_list_.end(),
                  rhs.extent_list_.begin()))
      return std::equal(begin(),end(),rhs.begin());
    else return false;
  }

  template <typename OPtr>
  bool operator<(const
                 const_multi_array_view<T,NumDims,OPtr>& rhs)
    const {
    return std::lexicographical_compare(begin(),end(),rhs.begin(),rhs.end());
  }

  template <typename OPtr>
  bool operator!=(const
                  const_multi_array_view<T,NumDims,OPtr>& rhs)
    const {
    return !(*this == rhs);
  }

  template <typename OPtr>
  bool operator>(const
                 const_multi_array_view<T,NumDims,OPtr>& rhs)
    const {
    return rhs < *this;
  }

  template <typename OPtr>
  bool operator<=(const
                 const_multi_array_view<T,NumDims,OPtr>& rhs)
    const {
    return !(*this > rhs);
  }

  template <typename OPtr>
  bool operator>=(const
                 const_multi_array_view<T,NumDims,OPtr>& rhs)
    const {
    return !(*this < rhs);
  }


#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
protected:
  template <typename,std::size_t> friend class multi_array_impl_base;
  template <typename,std::size_t,typename> friend class const_multi_array_view;
#else
public: // should be protected
#endif

  // This constructor is used by multi_array_impl_base::generate_array_view
  // to create strides
  template <typename ExtentList, typename Index>
  explicit const_multi_array_view(TPtr base,
                           const ExtentList& extents,
                           const boost::array<Index,NumDims>& strides):
    base_(base), origin_offset_(0) {

    index_base_list_.assign(0);

    // Get the extents and strides
    boost::detail::multi_array::
      copy_n(extents.begin(),NumDims,extent_list_.begin());
    boost::detail::multi_array::
      copy_n(strides.begin(),NumDims,stride_list_.begin());

    // Calculate the array size
    num_elements_ = std::accumulate(extent_list_.begin(),extent_list_.end(),
                                    size_type(1),std::multiplies<size_type>());
  }

  typedef boost::array<size_type,NumDims> size_list;
  typedef boost::array<index,NumDims> index_list;

  TPtr base_;
  index origin_offset_;
  size_type num_elements_;
  size_list extent_list_;
  index_list stride_list_;
  index_list index_base_list_;

private:
  // const_multi_array_view cannot be assigned to (no deep copies!)
  const_multi_array_view& operator=(const const_multi_array_view& other);
};


template <typename T, std::size_t NumDims>
class multi_array_view :
  public const_multi_array_view<T,NumDims,T*>
{
  typedef const_multi_array_view<T,NumDims,T*> super_type;
public:
  typedef typename super_type::value_type value_type;
  typedef typename super_type::reference reference;
  typedef typename super_type::iterator iterator;
  typedef typename super_type::reverse_iterator reverse_iterator;
  typedef typename super_type::const_reference const_reference;
  typedef typename super_type::const_iterator const_iterator;
  typedef typename super_type::const_reverse_iterator const_reverse_iterator;
  typedef typename super_type::element element;
  typedef typename super_type::size_type size_type;
  typedef typename super_type::difference_type difference_type;
  typedef typename super_type::index index;
  typedef typename super_type::extent_range extent_range;

  // template typedefs
  template <std::size_t NDims>
  struct const_array_view {
    typedef boost::detail::multi_array::const_multi_array_view<T,NDims> type;
  };

  template <std::size_t NDims>
  struct array_view {
    typedef boost::detail::multi_array::multi_array_view<T,NDims> type;
  };

  // Assignment from other ConstMultiArray types.
  template <typename ConstMultiArray>
  multi_array_view& operator=(const ConstMultiArray& other) {
    function_requires<
      boost::multi_array_concepts::
      ConstMultiArrayConcept<ConstMultiArray,NumDims> >();

    // make sure the dimensions agree
    BOOST_ASSERT(other.num_dimensions() == this->num_dimensions());
    BOOST_ASSERT(std::equal(other.shape(),other.shape()+this->num_dimensions(),
                            this->shape()));
    // iterator-based copy
    std::copy(other.begin(),other.end(),begin());
    return *this;
  }


  multi_array_view& operator=(const multi_array_view& other) {
    if (&other != this) {
      // make sure the dimensions agree
      BOOST_ASSERT(other.num_dimensions() == this->num_dimensions());
      BOOST_ASSERT(std::equal(other.shape(),
                              other.shape()+this->num_dimensions(),
                              this->shape()));
      // iterator-based copy
      std::copy(other.begin(),other.end(),begin());
    }
    return *this;
  }

  element* origin() { return this->base_+this->origin_offset_; }

  template <class IndexList>
  element& operator()(const IndexList& indices) {
    boost::function_requires<
      CollectionConcept<IndexList> >();
    return super_type::access_element(boost::type<element&>(),
                                      indices,origin(),
                                      this->shape(),this->strides(),
                                      this->index_bases());
  }


  reference operator[](index idx) {
    return super_type::access(boost::type<reference>(),
                              idx,origin(),
                              this->shape(),this->strides(),
                              this->index_bases());
  }


  // see generate_array_view in base.hpp
  template <int NDims>
  typename array_view<NDims>::type
  operator[](const boost::detail::multi_array::
             index_gen<NumDims,NDims>& indices) {
    typedef typename array_view<NDims>::type return_type;
    return
      super_type::generate_array_view(boost::type<return_type>(),
                                      indices,
                                      this->shape(),
                                      this->strides(),
                                      this->index_bases(),
                                      origin());
  }


  iterator begin() {
    return iterator(*this->index_bases(),origin(),
                    this->shape(),this->strides(),
                    this->index_bases());
  }

  iterator end() {
    return iterator(*this->index_bases()+(index)*this->shape(),origin(),
                    this->shape(),this->strides(),
                    this->index_bases());
  }

  reverse_iterator rbegin() {
    return reverse_iterator(end());
  }

  reverse_iterator rend() {
    return reverse_iterator(begin());
  }

  // Using declarations don't seem to work for g++
  // These are the proxies to work around this.

  const element* origin() const { return super_type::origin(); }

  template <class IndexList>
  const element& operator()(const IndexList& indices) const {
    boost::function_requires<
      CollectionConcept<IndexList> >();
    return super_type::operator()(indices);
  }

  const_reference operator[](index idx) const {
    return super_type::operator[](idx);
  }

  // see generate_array_view in base.hpp
  template <int NDims>
  typename const_array_view<NDims>::type
  operator[](const boost::detail::multi_array::
             index_gen<NumDims,NDims>& indices)
    const {
    return super_type::operator[](indices);
  }

  const_iterator begin() const {
    return super_type::begin();
  }

  const_iterator end() const {
    return super_type::end();
  }

  const_reverse_iterator rbegin() const {
    return super_type::rbegin();
  }

  const_reverse_iterator rend() const {
    return super_type::rend();
  }

#ifndef BOOST_NO_MEMBER_TEMPLATE_FRIENDS
private:
  template <typename,std::size_t> friend class multi_array_impl_base;
#else
public: // should be private
#endif

  // constructor used by multi_array_impl_base::generate_array_view to
  // generate array views
  template <typename ExtentList, typename Index>
  explicit multi_array_view(T* base,
                            const ExtentList& extents,
                            const boost::array<Index,NumDims>& strides) :
    super_type(base,extents,strides) { }

};

} // namespace multi_array
} // namespace detail

//
// traits classes to get array_view types
//
template <typename Array, int N>
class array_view_gen {
  typedef typename Array::element element;
public:
  typedef boost::detail::multi_array::multi_array_view<element,N> type;
};

template <typename Array, int N>
class const_array_view_gen {
  typedef typename Array::element element;
public:
  typedef boost::detail::multi_array::const_multi_array_view<element,N> type;
};

} // namespace boost

#endif