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pystrides_adaptor.hpp
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/***************************************************************************
* Copyright (c) Wolf Vollprecht, Johan Mabille and Sylvain Corlay *
* Copyright (c) QuantStack *
* *
* Distributed under the terms of the BSD 3-Clause License. *
* *
* The full license is in the file LICENSE, distributed with this software. *
****************************************************************************/
#ifndef PYSTRIDES_ADAPTOR_HPP
#define PYSTRIDES_ADAPTOR_HPP
#include <cstddef>
#include <iterator>
namespace xt
{
template <std::size_t N>
class pystrides_iterator;
/*********************************
* pystrides_adaptor declaration *
*********************************/
template <std::size_t N>
class pystrides_adaptor
{
public:
using value_type = std::ptrdiff_t;
using const_reference = value_type;
using reference = const_reference;
using const_pointer = const value_type*;
using pointer = const_pointer;
using size_type = std::size_t;
using difference_type = std::ptrdiff_t;
using const_iterator = pystrides_iterator<N>;
using iterator = const_iterator;
using const_reverse_iterator = std::reverse_iterator<const_iterator>;
using reverse_iterator = const_reverse_iterator;
using shape_type = size_t*;
pystrides_adaptor() = default;
pystrides_adaptor(const_pointer data, size_type size, shape_type shape);
bool empty() const noexcept;
size_type size() const noexcept;
const_reference operator[](size_type i) const;
const_reference front() const;
const_reference back() const;
const_iterator begin() const;
const_iterator end() const;
const_iterator cbegin() const;
const_iterator cend() const;
const_reverse_iterator rbegin() const;
const_reverse_iterator rend() const;
const_reverse_iterator crbegin() const;
const_reverse_iterator crend() const;
private:
const_pointer p_data;
size_type m_size;
shape_type p_shape;
};
/**********************************
* pystrides_iterator declaration *
**********************************/
template <std::size_t N>
class pystrides_iterator
{
public:
using self_type = pystrides_iterator<N>;
using value_type = typename pystrides_adaptor<N>::value_type;
using pointer = typename pystrides_adaptor<N>::const_pointer;
using reference = typename pystrides_adaptor<N>::const_reference;
using difference_type = typename pystrides_adaptor<N>::difference_type;
using iterator_category = std::random_access_iterator_tag;
using shape_pointer = typename pystrides_adaptor<N>::shape_type;
inline pystrides_iterator(pointer current, shape_pointer shape)
: p_current(current)
, p_shape(shape)
{
}
inline reference operator*() const
{
return *p_shape == size_t(1) ? 0 : *p_current / N;
}
inline pointer operator->() const
{
// Returning the address of a temporary
value_type res = this->operator*();
return &res;
}
inline reference operator[](difference_type n) const
{
return *(p_current + n) / N;
}
inline self_type& operator++()
{
++p_current;
++p_shape;
return *this;
}
inline self_type& operator--()
{
--p_current;
--p_shape;
return *this;
}
inline self_type operator++(int)
{
self_type tmp(*this);
++p_current;
++p_shape;
return tmp;
}
inline self_type operator--(int)
{
self_type tmp(*this);
--p_current;
--p_shape;
return tmp;
}
inline self_type& operator+=(difference_type n)
{
p_current += n;
p_shape += n;
return *this;
}
inline self_type& operator-=(difference_type n)
{
p_current -= n;
p_shape -= n;
return *this;
}
inline self_type operator+(difference_type n) const
{
return self_type(p_current + n, p_shape + n);
}
inline self_type operator-(difference_type n) const
{
return self_type(p_current - n, p_shape - n);
}
inline difference_type operator-(const self_type& rhs) const
{
self_type tmp(*this);
return p_current - rhs.p_current;
}
pointer get_pointer() const { return p_current; }
private:
pointer p_current;
shape_pointer p_shape;
};
template <std::size_t N>
inline bool operator==(const pystrides_iterator<N>& lhs,
const pystrides_iterator<N>& rhs)
{
return lhs.get_pointer() == rhs.get_pointer();
}
template <std::size_t N>
inline bool operator!=(const pystrides_iterator<N>& lhs,
const pystrides_iterator<N>& rhs)
{
return !(lhs == rhs);
}
template <std::size_t N>
inline bool operator<(const pystrides_iterator<N>& lhs,
const pystrides_iterator<N>& rhs)
{
return lhs.get_pointer() < rhs.get_pointer();
}
template <std::size_t N>
inline bool operator<=(const pystrides_iterator<N>& lhs,
const pystrides_iterator<N>& rhs)
{
return (lhs < rhs) || (lhs == rhs);
}
template <std::size_t N>
inline bool operator>(const pystrides_iterator<N>& lhs,
const pystrides_iterator<N>& rhs)
{
return !(lhs <= rhs);
}
template <std::size_t N>
inline bool operator>=(const pystrides_iterator<N>& lhs,
const pystrides_iterator<N>& rhs)
{
return !(lhs < rhs);
}
/************************************
* pystrides_adaptor implementation *
************************************/
template <std::size_t N>
inline pystrides_adaptor<N>::pystrides_adaptor(const_pointer data, size_type size, shape_type shape)
: p_data(data), m_size(size), p_shape(shape)
{
}
template <std::size_t N>
inline bool pystrides_adaptor<N>::empty() const noexcept
{
return m_size == 0;
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::size() const noexcept -> size_type
{
return m_size;
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::operator[](size_type i) const -> const_reference
{
return p_shape[i] == size_t(1) ? 0 : p_data[i] / N;
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::front() const -> const_reference
{
return this->operator[](0);
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::back() const -> const_reference
{
return this->operator[](m_size - 1);
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::begin() const -> const_iterator
{
return cbegin();
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::end() const -> const_iterator
{
return cend();
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::cbegin() const -> const_iterator
{
return const_iterator(p_data, p_shape);
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::cend() const -> const_iterator
{
return const_iterator(p_data + m_size, p_shape + m_size);
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::rbegin() const -> const_reverse_iterator
{
return crbegin();
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::rend() const -> const_reverse_iterator
{
return crend();
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::crbegin() const -> const_reverse_iterator
{
return const_reverse_iterator(cend());
}
template <std::size_t N>
inline auto pystrides_adaptor<N>::crend() const -> const_reverse_iterator
{
return const_reverse_iterator(cbegin());
}
}
#endif