pybind11/tests/test_buffers.py

import ctypes
import io
import struct

import pytest

import env
from pybind11_tests import ConstructorStats
from pybind11_tests import buffers as m

np = pytest.importorskip("numpy")

if m.long_double_and_double_have_same_size:
    # Determined by the compiler used to build the pybind11 tests
    # (e.g. MSVC gets here, but MinGW might not).
    np_float128 = None
    np_complex256 = None
else:
    # Determined by the compiler used to build numpy (e.g. MinGW).
    np_float128 = getattr(np, *["float128"] * 2)
    np_complex256 = getattr(np, *["complex256"] * 2)

CPP_NAME_FORMAT_NP_DTYPE_TABLE = [
    ("PyObject *", "O", object),
    ("bool", "?", np.bool_),
    ("std::int8_t", "b", np.int8),
    ("std::uint8_t", "B", np.uint8),
    ("std::int16_t", "h", np.int16),
    ("std::uint16_t", "H", np.uint16),
    ("std::int32_t", "i", np.int32),
    ("std::uint32_t", "I", np.uint32),
    ("std::int64_t", "q", np.int64),
    ("std::uint64_t", "Q", np.uint64),
    ("float", "f", np.float32),
    ("double", "d", np.float64),
    ("long double", "g", np_float128),
    ("std::complex<float>", "Zf", np.complex64),
    ("std::complex<double>", "Zd", np.complex128),
    ("std::complex<long double>", "Zg", np_complex256),
]
CPP_NAME_FORMAT_TABLE = [
    (cpp_name, format)
    for cpp_name, format, np_dtype in CPP_NAME_FORMAT_NP_DTYPE_TABLE
    if np_dtype is not None
]
CPP_NAME_NP_DTYPE_TABLE = [
    (cpp_name, np_dtype) for cpp_name, _, np_dtype in CPP_NAME_FORMAT_NP_DTYPE_TABLE
]


@pytest.mark.parametrize(("cpp_name", "np_dtype"), CPP_NAME_NP_DTYPE_TABLE)
def test_format_descriptor_format_buffer_info_equiv(cpp_name, np_dtype):
    if np_dtype is None:
        pytest.skip(
            f"cpp_name=`{cpp_name}`: `long double` and `double` have same size."
        )
    if isinstance(np_dtype, str):
        pytest.skip(f"np.{np_dtype} does not exist.")
    np_array = np.array([], dtype=np_dtype)
    for other_cpp_name, expected_format in CPP_NAME_FORMAT_TABLE:
        format, np_array_is_matching = m.format_descriptor_format_buffer_info_equiv(
            other_cpp_name, np_array
        )
        assert format == expected_format
        if other_cpp_name == cpp_name:
            assert np_array_is_matching
        else:
            assert not np_array_is_matching


def test_from_python():
    with pytest.raises(RuntimeError) as excinfo:
        m.Matrix(np.array([1, 2, 3]))  # trying to assign a 1D array
    assert str(excinfo.value) == "Incompatible buffer format!"

    m3 = np.array([[1, 2, 3], [4, 5, 6]]).astype(np.float32)
    m4 = m.Matrix(m3)

    for i in range(m4.rows()):
        for j in range(m4.cols()):
            assert m3[i, j] == m4[i, j]

    cstats = ConstructorStats.get(m.Matrix)
    assert cstats.alive() == 1
    del m3, m4
    assert cstats.alive() == 0
    assert cstats.values() == ["2x3 matrix"]
    assert cstats.copy_constructions == 0
    # assert cstats.move_constructions >= 0  # Don't invoke any
    assert cstats.copy_assignments == 0
    assert cstats.move_assignments == 0


# https://foss.heptapod.net/pypy/pypy/-/issues/2444
# TODO: fix on recent PyPy
@pytest.mark.xfail(
    env.PYPY, reason="PyPy 7.3.7 doesn't clear this anymore", strict=False
)
def test_to_python():
    mat = m.Matrix(5, 4)
    assert memoryview(mat).shape == (5, 4)

    assert mat[2, 3] == 0
    mat[2, 3] = 4.0
    mat[3, 2] = 7.0
    assert mat[2, 3] == 4
    assert mat[3, 2] == 7
    assert struct.unpack_from("f", mat, (3 * 4 + 2) * 4) == (7,)
    assert struct.unpack_from("f", mat, (2 * 4 + 3) * 4) == (4,)

    mat2 = np.array(mat, copy=False)
    assert mat2.shape == (5, 4)
    assert abs(mat2).sum() == 11
    assert mat2[2, 3] == 4
    assert mat2[3, 2] == 7
    mat2[2, 3] = 5
    assert mat2[2, 3] == 5

    cstats = ConstructorStats.get(m.Matrix)
    assert cstats.alive() == 1
    del mat
    pytest.gc_collect()
    assert cstats.alive() == 1
    del mat2  # holds a mat reference
    pytest.gc_collect()
    assert cstats.alive() == 0
    assert cstats.values() == ["5x4 matrix"]
    assert cstats.copy_constructions == 0
    # assert cstats.move_constructions >= 0  # Don't invoke any
    assert cstats.copy_assignments == 0
    assert cstats.move_assignments == 0


def test_inherited_protocol():
    """SquareMatrix is derived from Matrix and inherits the buffer protocol"""

    matrix = m.SquareMatrix(5)
    assert memoryview(matrix).shape == (5, 5)
    assert np.asarray(matrix).shape == (5, 5)


def test_pointer_to_member_fn():
    for cls in [m.Buffer, m.ConstBuffer, m.DerivedBuffer]:
        buf = cls()
        buf.value = 0x12345678
        value = struct.unpack("i", bytearray(buf))[0]
        assert value == 0x12345678


def test_readonly_buffer():
    buf = m.BufferReadOnly(0x64)
    view = memoryview(buf)
    assert view[0] == 0x64
    assert view.readonly
    with pytest.raises(TypeError):
        view[0] = 0


def test_selective_readonly_buffer():
    buf = m.BufferReadOnlySelect()

    memoryview(buf)[0] = 0x64
    assert buf.value == 0x64

    io.BytesIO(b"A").readinto(buf)
    assert buf.value == ord(b"A")

    buf.readonly = True
    with pytest.raises(TypeError):
        memoryview(buf)[0] = 0
    with pytest.raises(TypeError):
        io.BytesIO(b"1").readinto(buf)


def test_ctypes_array_1d():
    char1d = (ctypes.c_char * 10)()
    int1d = (ctypes.c_int * 15)()
    long1d = (ctypes.c_long * 7)()

    for carray in (char1d, int1d, long1d):
        info = m.get_buffer_info(carray)
        assert info.itemsize == ctypes.sizeof(carray._type_)
        assert info.size == len(carray)
        assert info.ndim == 1
        assert info.shape == [info.size]
        assert info.strides == [info.itemsize]
        assert not info.readonly


def test_ctypes_array_2d():
    char2d = ((ctypes.c_char * 10) * 4)()
    int2d = ((ctypes.c_int * 15) * 3)()
    long2d = ((ctypes.c_long * 7) * 2)()

    for carray in (char2d, int2d, long2d):
        info = m.get_buffer_info(carray)
        assert info.itemsize == ctypes.sizeof(carray[0]._type_)
        assert info.size == len(carray) * len(carray[0])
        assert info.ndim == 2
        assert info.shape == [len(carray), len(carray[0])]
        assert info.strides == [info.itemsize * len(carray[0]), info.itemsize]
        assert not info.readonly


def test_ctypes_from_buffer():
    test_pystr = b"0123456789"
    for pyarray in (test_pystr, bytearray(test_pystr)):
        pyinfo = m.get_buffer_info(pyarray)

        if pyinfo.readonly:
            cbytes = (ctypes.c_char * len(pyarray)).from_buffer_copy(pyarray)
            cinfo = m.get_buffer_info(cbytes)
        else:
            cbytes = (ctypes.c_char * len(pyarray)).from_buffer(pyarray)
            cinfo = m.get_buffer_info(cbytes)

        assert cinfo.size == pyinfo.size
        assert cinfo.ndim == pyinfo.ndim
        assert cinfo.shape == pyinfo.shape
        assert cinfo.strides == pyinfo.strides
        assert not cinfo.readonly


def test_buffer_docstring():
    assert (
        m.get_buffer_info.__doc__.strip()
        == "get_buffer_info(arg0: Buffer) -> pybind11_tests.buffers.buffer_info"
    )