pybind11/example/example7.cpp

116 lines
4.1 KiB
C++

/*
example/example7.cpp -- supporting Pythons' buffer protocol
Copyright (c) 2015 Wenzel Jakob <wenzel@inf.ethz.ch>
All rights reserved. Use of this source code is governed by a
BSD-style license that can be found in the LICENSE file.
*/
#include "example.h"
class Matrix {
public:
Matrix(size_t rows, size_t cols) : m_rows(rows), m_cols(cols) {
std::cout << "Value constructor: Creating a " << rows << "x" << cols << " matrix " << std::endl;
m_data = new float[rows*cols];
memset(m_data, 0, sizeof(float) * rows * cols);
}
Matrix(const Matrix &s) : m_rows(s.m_rows), m_cols(s.m_cols) {
std::cout << "Copy constructor: Creating a " << m_rows << "x" << m_cols << " matrix " << std::endl;
m_data = new float[m_rows * m_cols];
memcpy(m_data, s.m_data, sizeof(float) * m_rows * m_cols);
}
Matrix(Matrix &&s) : m_rows(s.m_rows), m_cols(s.m_cols), m_data(s.m_data) {
std::cout << "Move constructor: Creating a " << m_rows << "x" << m_cols << " matrix " << std::endl;
s.m_rows = 0;
s.m_cols = 0;
s.m_data = nullptr;
}
~Matrix() {
std::cout << "Freeing a " << m_rows << "x" << m_cols << " matrix " << std::endl;
delete[] m_data;
}
Matrix &operator=(const Matrix &s) {
std::cout << "Assignment operator : Creating a " << s.m_rows << "x" << s.m_cols << " matrix " << std::endl;
delete[] m_data;
m_rows = s.m_rows;
m_cols = s.m_cols;
m_data = new float[m_rows * m_cols];
memcpy(m_data, s.m_data, sizeof(float) * m_rows * m_cols);
return *this;
}
Matrix &operator=(Matrix &&s) {
std::cout << "Move assignment operator : Creating a " << s.m_rows << "x" << s.m_cols << " matrix " << std::endl;
if (&s != this) {
delete[] m_data;
m_rows = s.m_rows; m_cols = s.m_cols; m_data = s.m_data;
s.m_rows = 0; s.m_cols = 0; s.m_data = nullptr;
}
return *this;
}
float operator()(size_t i, size_t j) const {
return m_data[i*m_cols + j];
}
float &operator()(size_t i, size_t j) {
return m_data[i*m_cols + j];
}
float *data() { return m_data; }
size_t rows() const { return m_rows; }
size_t cols() const { return m_cols; }
private:
size_t m_rows;
size_t m_cols;
float *m_data;
};
void init_ex7(py::module &m) {
py::class_<Matrix> mtx(m, "Matrix");
mtx.def(py::init<size_t, size_t>())
/// Construct from a buffer
.def("__init__", [](Matrix &v, py::buffer b) {
py::buffer_info info = b.request();
if (info.format != py::format_descriptor<float>::value() || info.ndim != 2)
throw std::runtime_error("Incompatible buffer format!");
new (&v) Matrix(info.shape[0], info.shape[1]);
memcpy(v.data(), info.ptr, sizeof(float) * v.rows() * v.cols());
})
.def("rows", &Matrix::rows)
.def("cols", &Matrix::cols)
/// Bare bones interface
.def("__getitem__", [](const Matrix &m, std::pair<size_t, size_t> i) {
if (i.first >= m.rows() || i.second >= m.cols())
throw py::index_error();
return m(i.first, i.second);
})
.def("__setitem__", [](Matrix &m, std::pair<size_t, size_t> i, float v) {
if (i.first >= m.rows() || i.second >= m.cols())
throw py::index_error();
m(i.first, i.second) = v;
})
/// Provide buffer access
.def_buffer([](Matrix &m) -> py::buffer_info {
return py::buffer_info(
m.data(), /* Pointer to buffer */
sizeof(float), /* Size of one scalar */
py::format_descriptor<float>::value(), /* Python struct-style format descriptor */
2, /* Number of dimensions */
{ m.rows(), m.cols() }, /* Buffer dimensions */
{ sizeof(float) * m.rows(), /* Strides (in bytes) for each index */
sizeof(float) }
);
});
}