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Simplify byte_offset #7

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Merged
SylvainCorlay merged 1 commit into from
Nov 15, 2016
Merged

Simplify byte_offset #7

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16 changes: 3 additions & 13 deletions include/xtensor-python/pyarray.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -330,24 +330,14 @@ namespace xt
template<typename... Args>
inline auto pyarray<T, ExtraFlags>::operator()(Args... args) -> reference
{
if (sizeof...(args) != dimension())
{
pybind_array::fail_dim_check(sizeof...(args), "index dimension mismatch");
}
// not using pybind_array::offset_at() / index_at() here so as to avoid another dimension check.
return *(static_cast<pointer>(pybind_array::mutable_data()) + pybind_array::get_byte_offset(args...) / itemsize());
return *(static_cast<pointer>(pybind_array::mutable_data()) + pybind_array::byte_offset(args...) / itemsize());
}

template <class T, int ExtraFlags>
template<typename... Args>
inline auto pyarray<T, ExtraFlags>::operator()(Args... args) const -> const_reference
{
if (sizeof...(args) != dimension())
{
pybind_array::fail_dim_check(sizeof...(args), "index dimension mismatch");
}
// not using pybind_array::offset_at() / index_at() here so as to avoid another dimension check.
return *(static_cast<const_pointer>(pybind_array::data()) + pybind_array::get_byte_offset(args...) / itemsize());
return *(static_cast<const_pointer>(pybind_array::data()) + pybind_array::byte_offset(args...) / itemsize());
}

template <class T, int ExtraFlags>
Expand Down Expand Up @@ -522,7 +512,7 @@ namespace xt
template<typename... Args>
inline auto pyarray<T, ExtraFlags>::index_at(Args... args) const -> size_type
{
return pybind_array::offset_at(args...) / itemsize();
return pybind_array::byte_offset(args...) / itemsize();
}

template <class T, int ExtraFlags>
Expand Down
45 changes: 7 additions & 38 deletions include/xtensor-python/pybind11_backport.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -91,7 +91,7 @@ namespace pybind11

size_type size() const
{
return std::accumulate(shape(), shape() + ndim(), size_type{1}, std::multiplies<size_type>());
return std::accumulate(shape(), shape() + ndim(), size_type(1), std::multiplies<size_type>());
}

size_type itemsize() const
Expand All @@ -114,61 +114,30 @@ namespace pybind11
return reinterpret_cast<const size_type*>(PyArray_GET_(m_ptr, strides));
}

template<typename... Ix>
void* data()
{
return static_cast<void*>(PyArray_GET_(m_ptr, data));
}

template<typename... Ix>
void* mutable_data()
{
// check_writeable();
return static_cast<void *>(PyArray_GET_(m_ptr, data));
}

template<typename... Ix>
size_type offset_at(Ix... index) const
{
if (sizeof...(index) > ndim())
{
fail_dim_check(sizeof...(index), "too many indices for an array");
}
return get_byte_offset(index...);
}
protected:

size_type offset_at() const
template<size_t dim = 0>
inline size_type byte_offset() const
{
return 0;
}

protected:

void fail_dim_check(size_type dim, const std::string& msg) const
template <size_t dim = 0, class... Args>
inline size_type byte_offset(size_type i, Args... args) const
{
throw index_error(msg + ": " + std::to_string(dim) +
" (ndim = " + std::to_string(ndim()) + ")");
return i * strides()[dim] + byte_offset<dim + 1>(args...);
}

template<typename... Ix>
size_type get_byte_offset(Ix... index) const
{
const size_type idx[] = { static_cast<size_type>(index)... };
if (!std::equal(idx + 0, idx + sizeof...(index), shape(), std::less<size_type>{}))
{
auto mismatch = std::mismatch(idx + 0, idx + sizeof...(index), shape(), std::less<size_type>{});
throw index_error(std::string("index ") + std::to_string(*mismatch.first) +
" is out of bounds for axis " + std::to_string(mismatch.first - idx) +
" with size " + std::to_string(*mismatch.second));
}
return std::inner_product(idx + 0, idx + sizeof...(index), strides(), size_type{0});
}

size_type get_byte_offset() const
{
return 0;
}

static std::vector<size_type>
default_strides(const std::vector<size_type>& shape, size_type itemsize)
{
Expand Down