xtensor-python/include/xtensor-python/pystrides_adaptor.hpp at master · Roy-Kid/xtensor-python · GitHub

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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,