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Backstrides iteration #110

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Merged
JohanMabille merged 1 commit into from
Sep 6, 2017
Merged

Backstrides iteration #110

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211 changes: 210 additions & 1 deletion include/xtensor-python/pyarray.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -75,21 +75,183 @@ namespace pybind11
namespace xt
{

/**************************
* pybackstrides_iterator *
**************************/

template <class B>
class pybackstrides_iterator
{
public:

using self_type = pybackstrides_iterator<B>;

using value_type = typename B::value_type;
using pointer = const value_type*;
using reference = value_type;
using difference_type = std::ptrdiff_t;
using iterator_category = std::random_access_iterator_tag;

inline pybackstrides_iterator(const B* b, std::size_t offset)
: p_b(b), m_offset(offset)
{
}

inline reference operator*() const
{
return p_b->operator[](m_offset);
}

inline pointer operator->() const
{
// Returning the address of a temporary
value_type res = p_b->operator[](m_offset);
return &res;
}

inline reference operator[](difference_type n) const
{
return p_b->operator[](m_offset + n);
}

inline self_type& operator++()
{
++m_offset;
return *this;
}

inline self_type& operator--()
{
--m_offset;
return *this;
}

inline self_type operator++(int)
{
self_type tmp(*this);
++m_offset;
return tmp;
}

inline self_type operator--(int)
{
self_type tmp(*this);
--m_offset;
return tmp;
}

inline self_type& operator+=(difference_type n)
{
m_offset += n;
return *this;
}

inline self_type& operator-=(difference_type n)
{
m_offset -= n;
return *this;
}

inline self_type operator+(difference_type n) const
{
return self_type(p_b, m_offset + n);
}

inline self_type operator-(difference_type n) const
{
return self_type(p_b, m_offset - n);
}

inline self_type operator-(const self_type& rhs) const
{
self_type tmp(*this);
tmp -= (m_offset - rhs.m_offset);
return tmp;
}

inline std::size_t offset() const
{
return m_offset;
}

private:

const B* p_b;
std::size_t m_offset;
};

template <class B>
inline bool operator==(const pybackstrides_iterator<B>& lhs,
const pybackstrides_iterator<B>& rhs)
{
return lhs.offset() == rhs.offset();
}

template <class B>
inline bool operator!=(const pybackstrides_iterator<B>& lhs,
const pybackstrides_iterator<B>& rhs)
{
return !(lhs == rhs);
}

template <class B>
inline bool operator<(const pybackstrides_iterator<B>& lhs,
const pybackstrides_iterator<B>& rhs)
{
return lhs.offset() < rhs.offset();
}

template <class B>
inline bool operator<=(const pybackstrides_iterator<B>& lhs,
const pybackstrides_iterator<B>& rhs)
{
return (lhs < rhs) || (lhs == rhs);
}

template <class B>
inline bool operator>(const pybackstrides_iterator<B>& lhs,
const pybackstrides_iterator<B>& rhs)
{
return !(lhs <= rhs);
}

template <class B>
inline bool operator>=(const pybackstrides_iterator<B>& lhs,
const pybackstrides_iterator<B>& rhs)
{
return !(lhs < rhs);
}

template <class A>
class pyarray_backstrides
{
public:

using self_type = pyarray_backstrides<A>;
using array_type = A;
using value_type = typename array_type::size_type;
using const_reference = value_type;
using const_pointer = const value_type*;
using size_type = typename array_type::size_type;
using difference_type = typename array_type::difference_type;

using const_iterator = pybackstrides_iterator<self_type>;

pyarray_backstrides() = default;
pyarray_backstrides(const array_type& a);

bool empty() const;
size_type size() const;

value_type operator[](size_type i) const;

size_type size() 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;

private:

Expand Down Expand Up @@ -213,6 +375,12 @@ namespace xt
{
}

template <class A>
inline bool pyarray_backstrides<A>::empty() const
{
return p_a->dimension() == 0;
}

template <class A>
inline auto pyarray_backstrides<A>::size() const -> size_type
{
Expand All @@ -227,6 +395,47 @@ namespace xt
return res;
}

template <class A>
inline auto pyarray_backstrides<A>::front() const -> const_reference
{
value_type sh = p_a->shape()[0];
value_type res = sh == 1 ? 0 : (sh - 1) * p_a->strides()[0];
return res;
}

template <class A>
inline auto pyarray_backstrides<A>::back() const -> const_reference
{
auto index = p_a->size() - 1;
value_type sh = p_a->shape()[index];
value_type res = sh == 1 ? 0 : (sh - 1) * p_a->strides()[index];
return res;
}

template <class A>
inline auto pyarray_backstrides<A>::begin() const -> const_iterator
{
return cbegin();
}

template <class A>
inline auto pyarray_backstrides<A>::end() const -> const_iterator
{
return cend();
}

template <class A>
inline auto pyarray_backstrides<A>::cbegin() const -> const_iterator
{
const_iterator(this, 0);
}

template <class A>
inline auto pyarray_backstrides<A>::cend() const -> const_iterator
{
const_iterator(this, size());
}

/**************************
* pyarray implementation *
**************************/
Expand Down
51 changes: 38 additions & 13 deletions include/xtensor-python/pystrides_adaptor.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -18,6 +18,10 @@ namespace xt
template <std::size_t N>
class pystrides_iterator;

/*********************************
* pystrides_adaptor declaration *
*********************************/

template <std::size_t N>
class pystrides_adaptor
{
Expand Down Expand Up @@ -53,14 +57,13 @@ namespace xt
size_type m_size;
};

/*************************************
* pystrides_iterator implementation *
*************************************/
/**********************************
* pystrides_iterator declaration *
**********************************/

template <std::size_t N>
class pystrides_iterator
{

public:

using self_type = pystrides_iterator<N>;
Expand All @@ -76,16 +79,29 @@ namespace xt
{
}

inline reference operator*() const { return *p_current / N; }
inline pointer operator->() const { return p_current; }
inline reference operator*() const
{
return *p_current / N;
}

inline reference operator[](difference_type n) const { return *(p_current + n) / N; }
inline pointer operator->() const
{
// Returning the address of a temporary
value_type res = *p_current / N;
return &res;
}

inline reference operator[](difference_type n) const
{
return *(p_current + n) / N;
}

inline self_type& operator++()
{
++p_current;
return *this;
}

inline self_type& operator--()
{
--p_current;
Expand All @@ -110,14 +126,23 @@ namespace xt
p_current += n;
return *this;
}

inline self_type& operator-=(difference_type n)
{
p_current -= n;
return *this;
}

inline self_type operator+(difference_type n) const { return self_type(p_current + n); }
inline self_type operator-(difference_type n) const { return self_type(p_current - n); }
inline self_type operator+(difference_type n) const
{
return self_type(p_current + n);
}

inline self_type operator-(difference_type n) const
{
return self_type(p_current - n);
}

inline self_type operator-(const self_type& rhs) const
{
self_type tmp(*this);
Expand Down Expand Up @@ -217,25 +242,25 @@ namespace xt
template <std::size_t N>
inline auto pystrides_adaptor<N>::begin() const -> const_iterator
{
return const_iterator(p_data);
return cbegin();
}

template <std::size_t N>
inline auto pystrides_adaptor<N>::end() const -> const_iterator
{
return const_iterator(p_data + m_size);
return cend();
}

template <std::size_t N>
inline auto pystrides_adaptor<N>::cbegin() const -> const_iterator
{
return begin();
return const_iterator(p_data);
}

template <std::size_t N>
inline auto pystrides_adaptor<N>::cend() const -> const_iterator
{
return end();
return const_iterator(p_data + m_size);
}
}

Expand Down