2 pybind11/buffer_info.h: Python buffer object interface
4 Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch>
6 All rights reserved. Use of this source code is governed by a
7 BSD-style license that can be found in the LICENSE file.
12 #include "detail/common.h"
14 NAMESPACE_BEGIN(PYBIND11_NAMESPACE)
16 /// Information record describing a Python buffer object
18 void *ptr = nullptr; // Pointer to the underlying storage
19 ssize_t itemsize = 0; // Size of individual items in bytes
20 ssize_t size = 0; // Total number of entries
21 std::string format; // For homogeneous buffers, this should be set to format_descriptor<T>::format()
22 ssize_t ndim = 0; // Number of dimensions
23 std::vector<ssize_t> shape; // Shape of the tensor (1 entry per dimension)
24 std::vector<ssize_t> strides; // Number of bytes between adjacent entries (for each per dimension)
25 bool readonly = false; // flag to indicate if the underlying storage may be written to
29 buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t ndim,
30 detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in, bool readonly=false)
31 : ptr(ptr), itemsize(itemsize), size(1), format(format), ndim(ndim),
32 shape(std::move(shape_in)), strides(std::move(strides_in)), readonly(readonly) {
33 if (ndim != (ssize_t) shape.size() || ndim != (ssize_t) strides.size())
34 pybind11_fail("buffer_info: ndim doesn't match shape and/or strides length");
35 for (size_t i = 0; i < (size_t) ndim; ++i)
40 buffer_info(T *ptr, detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in, bool readonly=false)
41 : buffer_info(private_ctr_tag(), ptr, sizeof(T), format_descriptor<T>::format(), static_cast<ssize_t>(shape_in->size()), std::move(shape_in), std::move(strides_in), readonly) { }
43 buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t size, bool readonly=false)
44 : buffer_info(ptr, itemsize, format, 1, {size}, {itemsize}, readonly) { }
47 buffer_info(T *ptr, ssize_t size, bool readonly=false)
48 : buffer_info(ptr, sizeof(T), format_descriptor<T>::format(), size, readonly) { }
51 buffer_info(const T *ptr, ssize_t size, bool readonly=true)
52 : buffer_info(const_cast<T*>(ptr), sizeof(T), format_descriptor<T>::format(), size, readonly) { }
54 explicit buffer_info(Py_buffer *view, bool ownview = true)
55 : buffer_info(view->buf, view->itemsize, view->format, view->ndim,
56 {view->shape, view->shape + view->ndim}, {view->strides, view->strides + view->ndim}, view->readonly) {
58 this->ownview = ownview;
61 buffer_info(const buffer_info &) = delete;
62 buffer_info& operator=(const buffer_info &) = delete;
64 buffer_info(buffer_info &&other) {
65 (*this) = std::move(other);
68 buffer_info& operator=(buffer_info &&rhs) {
70 itemsize = rhs.itemsize;
72 format = std::move(rhs.format);
74 shape = std::move(rhs.shape);
75 strides = std::move(rhs.strides);
76 std::swap(view, rhs.view);
77 std::swap(ownview, rhs.ownview);
78 readonly = rhs.readonly;
83 if (view && ownview) { PyBuffer_Release(view); delete view; }
87 struct private_ctr_tag { };
89 buffer_info(private_ctr_tag, void *ptr, ssize_t itemsize, const std::string &format, ssize_t ndim,
90 detail::any_container<ssize_t> &&shape_in, detail::any_container<ssize_t> &&strides_in, bool readonly)
91 : buffer_info(ptr, itemsize, format, ndim, std::move(shape_in), std::move(strides_in), readonly) { }
93 Py_buffer *view = nullptr;
97 NAMESPACE_BEGIN(detail)
99 template <typename T, typename SFINAE = void> struct compare_buffer_info {
100 static bool compare(const buffer_info& b) {
101 return b.format == format_descriptor<T>::format() && b.itemsize == (ssize_t) sizeof(T);
105 template <typename T> struct compare_buffer_info<T, detail::enable_if_t<std::is_integral<T>::value>> {
106 static bool compare(const buffer_info& b) {
107 return (size_t) b.itemsize == sizeof(T) && (b.format == format_descriptor<T>::value ||
108 ((sizeof(T) == sizeof(long)) && b.format == (std::is_unsigned<T>::value ? "L" : "l")) ||
109 ((sizeof(T) == sizeof(size_t)) && b.format == (std::is_unsigned<T>::value ? "N" : "n")));
113 NAMESPACE_END(detail)
114 NAMESPACE_END(PYBIND11_NAMESPACE)