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test_buffers.cpp
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Wed, Nov 27, 11:02

test_buffers.cpp
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/*
tests/test_buffers.cpp -- supporting Pythons' buffer protocol
Copyright (c) 2016 Wenzel Jakob <wenzel.jakob@epfl.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 "pybind11_tests.h"
#include "constructor_stats.h"
TEST_SUBMODULE(buffers, m) {
// test_from_python / test_to_python:
class Matrix {
public:
Matrix(ssize_t rows, ssize_t cols) : m_rows(rows), m_cols(cols) {
print_created(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
m_data = new float[(size_t) (rows*cols)];
memset(m_data, 0, sizeof(float) * (size_t) (rows * cols));
}
Matrix(const Matrix &s) : m_rows(s.m_rows), m_cols(s.m_cols) {
print_copy_created(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
m_data = new float[(size_t) (m_rows * m_cols)];
memcpy(m_data, s.m_data, sizeof(float) * (size_t) (m_rows * m_cols));
}
Matrix(Matrix &&s) : m_rows(s.m_rows), m_cols(s.m_cols), m_data(s.m_data) {
print_move_created(this);
s.m_rows = 0;
s.m_cols = 0;
s.m_data = nullptr;
}
~Matrix() {
print_destroyed(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
delete[] m_data;
}
Matrix &operator=(const Matrix &s) {
print_copy_assigned(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
delete[] m_data;
m_rows = s.m_rows;
m_cols = s.m_cols;
m_data = new float[(size_t) (m_rows * m_cols)];
memcpy(m_data, s.m_data, sizeof(float) * (size_t) (m_rows * m_cols));
return *this;
}
Matrix &operator=(Matrix &&s) {
print_move_assigned(this, std::to_string(m_rows) + "x" + std::to_string(m_cols) + " matrix");
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()(ssize_t i, ssize_t j) const {
return m_data[(size_t) (i*m_cols + j)];
}
float &operator()(ssize_t i, ssize_t j) {
return m_data[(size_t) (i*m_cols + j)];
}
float *data() { return m_data; }
ssize_t rows() const { return m_rows; }
ssize_t cols() const { return m_cols; }
private:
ssize_t m_rows;
ssize_t m_cols;
float *m_data;
};
py::class_<Matrix>(m, "Matrix", py::buffer_protocol())
.def(py::init<ssize_t, ssize_t>())
/// Construct from a buffer
.def(py::init([](py::buffer b) {
py::buffer_info info = b.request();
if (info.format != py::format_descriptor<float>::format() || info.ndim != 2)
throw std::runtime_error("Incompatible buffer format!");
auto v = new Matrix(info.shape[0], info.shape[1]);
memcpy(v->data(), info.ptr, sizeof(float) * (size_t) (v->rows() * v->cols()));
return v;
}))
.def("rows", &Matrix::rows)
.def("cols", &Matrix::cols)
/// Bare bones interface
.def("__getitem__", [](const Matrix &m, std::pair<ssize_t, ssize_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<ssize_t, ssize_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 */
{ m.rows(), m.cols() }, /* Buffer dimensions */
{ sizeof(float) * size_t(m.cols()), /* Strides (in bytes) for each index */
sizeof(float) }
);
})
;
// test_inherited_protocol
class SquareMatrix : public Matrix {
public:
SquareMatrix(ssize_t n) : Matrix(n, n) { }
};
// Derived classes inherit the buffer protocol and the buffer access function
py::class_<SquareMatrix, Matrix>(m, "SquareMatrix")
.def(py::init<ssize_t>());
// test_pointer_to_member_fn
// Tests that passing a pointer to member to the base class works in
// the derived class.
struct Buffer {
int32_t value = 0;
py::buffer_info get_buffer_info() {
return py::buffer_info(&value, sizeof(value),
py::format_descriptor<int32_t>::format(), 1);
}
};
py::class_<Buffer>(m, "Buffer", py::buffer_protocol())
.def(py::init<>())
.def_readwrite("value", &Buffer::value)
.def_buffer(&Buffer::get_buffer_info);
class ConstBuffer {
std::unique_ptr<int32_t> value;
public:
int32_t get_value() const { return *value; }
void set_value(int32_t v) { *value = v; }
py::buffer_info get_buffer_info() const {
return py::buffer_info(value.get(), sizeof(*value),
py::format_descriptor<int32_t>::format(), 1);
}
ConstBuffer() : value(new int32_t{0}) { };
};
py::class_<ConstBuffer>(m, "ConstBuffer", py::buffer_protocol())
.def(py::init<>())
.def_property("value", &ConstBuffer::get_value, &ConstBuffer::set_value)
.def_buffer(&ConstBuffer::get_buffer_info);
struct DerivedBuffer : public Buffer { };
py::class_<DerivedBuffer>(m, "DerivedBuffer", py::buffer_protocol())
.def(py::init<>())
.def_readwrite("value", (int32_t DerivedBuffer::*) &DerivedBuffer::value)
.def_buffer(&DerivedBuffer::get_buffer_info);
}

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