1/* 2 pybind11/buffer_info.h: Python buffer object interface 3 4 Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.ch> 5 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. 8*/ 9 10#pragma once 11 12#include "detail/common.h" 13 14NAMESPACE_BEGIN(PYBIND11_NAMESPACE) 15 16/// Information record describing a Python buffer object 17struct buffer_info { 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 entries between adjacent entries (for each per dimension) 25 26 buffer_info() { } 27 28 buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t ndim, 29 detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in) 30 : ptr(ptr), itemsize(itemsize), size(1), format(format), ndim(ndim), 31 shape(std::move(shape_in)), strides(std::move(strides_in)) { 32 if (ndim != (ssize_t) shape.size() || ndim != (ssize_t) strides.size()) 33 pybind11_fail("buffer_info: ndim doesn't match shape and/or strides length"); 34 for (size_t i = 0; i < (size_t) ndim; ++i) 35 size *= shape[i]; 36 } 37 38 template <typename T> 39 buffer_info(T *ptr, detail::any_container<ssize_t> shape_in, detail::any_container<ssize_t> strides_in) 40 : 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)) { } 41 42 buffer_info(void *ptr, ssize_t itemsize, const std::string &format, ssize_t size) 43 : buffer_info(ptr, itemsize, format, 1, {size}, {itemsize}) { } 44 45 template <typename T> 46 buffer_info(T *ptr, ssize_t size) 47 : buffer_info(ptr, sizeof(T), format_descriptor<T>::format(), size) { } 48 49 explicit buffer_info(Py_buffer *view, bool ownview = true) 50 : buffer_info(view->buf, view->itemsize, view->format, view->ndim, 51 {view->shape, view->shape + view->ndim}, {view->strides, view->strides + view->ndim}) { 52 this->view = view; 53 this->ownview = ownview; 54 } 55 56 buffer_info(const buffer_info &) = delete; 57 buffer_info& operator=(const buffer_info &) = delete; 58 59 buffer_info(buffer_info &&other) { 60 (*this) = std::move(other); 61 } 62 63 buffer_info& operator=(buffer_info &&rhs) { 64 ptr = rhs.ptr; 65 itemsize = rhs.itemsize; 66 size = rhs.size; 67 format = std::move(rhs.format); 68 ndim = rhs.ndim; 69 shape = std::move(rhs.shape); 70 strides = std::move(rhs.strides); 71 std::swap(view, rhs.view); 72 std::swap(ownview, rhs.ownview); 73 return *this; 74 } 75 76 ~buffer_info() { 77 if (view && ownview) { PyBuffer_Release(view); delete view; } 78 } 79 80private: 81 struct private_ctr_tag { }; 82 83 buffer_info(private_ctr_tag, void *ptr, ssize_t itemsize, const std::string &format, ssize_t ndim, 84 detail::any_container<ssize_t> &&shape_in, detail::any_container<ssize_t> &&strides_in) 85 : buffer_info(ptr, itemsize, format, ndim, std::move(shape_in), std::move(strides_in)) { } 86 87 Py_buffer *view = nullptr; 88 bool ownview = false; 89}; 90 91NAMESPACE_BEGIN(detail) 92 93template <typename T, typename SFINAE = void> struct compare_buffer_info { 94 static bool compare(const buffer_info& b) { 95 return b.format == format_descriptor<T>::format() && b.itemsize == (ssize_t) sizeof(T); 96 } 97}; 98 99template <typename T> struct compare_buffer_info<T, detail::enable_if_t<std::is_integral<T>::value>> { 100 static bool compare(const buffer_info& b) { 101 return (size_t) b.itemsize == sizeof(T) && (b.format == format_descriptor<T>::value || 102 ((sizeof(T) == sizeof(long)) && b.format == (std::is_unsigned<T>::value ? "L" : "l")) || 103 ((sizeof(T) == sizeof(size_t)) && b.format == (std::is_unsigned<T>::value ? "N" : "n"))); 104 } 105}; 106 107NAMESPACE_END(detail) 108NAMESPACE_END(PYBIND11_NAMESPACE) 109