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/*
* tensorview_iterator.h
*
* Created on: Dec 28, 2013
* Author: evaleev
*/
#ifndef BTAS_TENSORVIEW_ITERATOR_H_
#define BTAS_TENSORVIEW_ITERATOR_H_
#include <cstddef>
#include <btas/storage_traits.h>
namespace btas {
/// Iterates over elements of \c Storage using ordinal values of indices in \c Range
template <typename Range, typename Storage>
class TensorViewIterator : public std::iterator<typename std::conditional<std::is_const<Storage>::value,
std::forward_iterator_tag,
std::output_iterator_tag>::type,
typename std::conditional<std::is_const<Storage>::value,
const typename storage_traits<Storage>::value_type,
typename storage_traits<Storage>::value_type>::type>
{
struct Enabler {};
public:
typedef Storage storage_type;
typedef std::reference_wrapper<storage_type> storageref_type;
typedef std::reference_wrapper<const storage_type> ncstorageref_type;
typedef std::iterator<typename std::conditional<std::is_const<Storage>::value,
std::forward_iterator_tag,
std::output_iterator_tag>::type,
typename std::conditional<std::is_const<Storage>::value,
const typename storage_traits<Storage>::value_type,
typename storage_traits<Storage>::value_type>::type> base_type;
using typename base_type::value_type;
using typename base_type::pointer;
using typename base_type::reference;
using typename base_type::difference_type;
using typename base_type::iterator_category;
private:
typedef typename Range::ordinal_subiterator subiterator;
typedef typename Range::ordinal_iterator iterator;
typedef typename iterator::value_type ordinal_type;
typedef typename Range::index_type index_type;
public:
/// Default constructor
TensorViewIterator() {}
/// Destructor
~TensorViewIterator() {}
TensorViewIterator(const typename Range::iterator& index_iter,
Storage& storage) :
iter_(subiterator(std::make_pair(*index_iter,index_iter.range()->ordinal(*index_iter)),index_iter.range())),
storageref_(storage) {}
TensorViewIterator(const typename Range::iterator& index_iter,
const storageref_type& storage) :
iter_(subiterator(std::make_pair(*index_iter,index_iter.range()->ordinal(*index_iter)),index_iter.range())),
storageref_(storage) {}
template <typename S = Storage>
TensorViewIterator(const typename Range::iterator& index_iter,
const ncstorageref_type& storage,
typename std::enable_if<std::is_const<S>::value>::type* = 0) :
iter_(subiterator(std::make_pair(*index_iter,index_iter.range()->ordinal(*index_iter)),index_iter.range())),
// standard const_cast cannot "map" const into nontrivial structures, have to reinterpret here
storageref_(reinterpret_cast<const storageref_type&>(storage)) {}
TensorViewIterator(const typename Range::iterator& index_iter,
const ordinal_type& ord,
Storage& storage) :
iter_(subiterator(std::make_pair(*index_iter,ord),index_iter.range())),
storageref_(storage) {}
TensorViewIterator(const iterator& iter,
Storage& storage) :
iter_(iter), storageref_(storage) {}
TensorViewIterator(iterator&& iter,
Storage& storage) :
iter_(iter), storageref_(storage) {}
TensorViewIterator& operator++() {
++iter_;
return *this;
}
const reference operator*() const {
return *(cbegin(storageref_.get()) + *iter_);
}
//template <class = typename std::enable_if<not std::is_const<storage_type>::value,Enabler>::type>
template <typename S = Storage>
typename std::enable_if<not std::is_const<S>::value,reference>::type
operator*() {
return *(begin(storageref_.get()) + *iter_);
}
const index_type& index() const {
return first(*iter_.base());
}
template <typename R, typename S>
friend bool operator==(const TensorViewIterator<R,S>&, const TensorViewIterator<R,S>&);
private:
iterator iter_;
storageref_type storageref_;
};
template <typename Range, typename Storage>
inline bool operator==(const TensorViewIterator<Range,Storage>& i1,
const TensorViewIterator<Range,Storage>& i2) {
return i1.iter_ == i2.iter_;
}
template <typename Range, typename Storage>
inline bool operator!=(const TensorViewIterator<Range,Storage>& i1,
const TensorViewIterator<Range,Storage>& i2) {
return not (i1 == i2);
}
}
#endif /* BTAS_TENSORVIEW_ITERATOR_H_ */
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