Issue #15944: memoryview: Allow arbitrary formats when casting to bytes.

Original patch by Martin Panter.
This commit is contained in:
Stefan Krah 2015-08-08 13:38:10 +02:00
parent 917c2c3654
commit 0c51595a78
5 changed files with 57 additions and 11 deletions

View File

@ -3564,7 +3564,7 @@ copying.
the buffer itself is not copied. Supported casts are 1D -> C-contiguous
and C-contiguous -> 1D.
Both formats are restricted to single element native formats in
The destination format is restricted to a single element native format in
:mod:`struct` syntax. One of the formats must be a byte format
('B', 'b' or 'c'). The byte length of the result must be the same
as the original length.
@ -3645,6 +3645,9 @@ copying.
.. versionadded:: 3.3
.. versionchanged:: 3.5
The source format is no longer restricted when casting to a byte view.
There are also several readonly attributes available:
.. attribute:: obj

View File

@ -2559,8 +2559,7 @@ class TestBufferProtocol(unittest.TestCase):
ex = ndarray(sitems, shape=[1], format=sfmt)
msrc = memoryview(ex)
for dfmt, _, _ in iter_format(1):
if (not is_memoryview_format(sfmt) or
not is_memoryview_format(dfmt)):
if not is_memoryview_format(dfmt):
self.assertRaises(ValueError, msrc.cast, dfmt,
[32//dsize])
else:
@ -2773,6 +2772,32 @@ class TestBufferProtocol(unittest.TestCase):
ndim=ndim, shape=shape, strides=strides,
lst=lst, cast=True)
if ctypes:
# format: "T{>l:x:>d:y:}"
class BEPoint(ctypes.BigEndianStructure):
_fields_ = [("x", ctypes.c_long), ("y", ctypes.c_double)]
point = BEPoint(100, 200.1)
m1 = memoryview(point)
m2 = m1.cast('B')
self.assertEqual(m2.obj, point)
self.assertEqual(m2.itemsize, 1)
self.assertEqual(m2.readonly, 0)
self.assertEqual(m2.ndim, 1)
self.assertEqual(m2.shape, (m2.nbytes,))
self.assertEqual(m2.strides, (1,))
self.assertEqual(m2.suboffsets, ())
x = ctypes.c_double(1.2)
m1 = memoryview(x)
m2 = m1.cast('c')
self.assertEqual(m2.obj, x)
self.assertEqual(m2.itemsize, 1)
self.assertEqual(m2.readonly, 0)
self.assertEqual(m2.ndim, 1)
self.assertEqual(m2.shape, (m2.nbytes,))
self.assertEqual(m2.strides, (1,))
self.assertEqual(m2.suboffsets, ())
def test_memoryview_tolist(self):
# Most tolist() tests are in self.verify() etc.

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@ -492,5 +492,26 @@ class ArrayMemorySliceSliceTest(unittest.TestCase,
pass
class OtherTest(unittest.TestCase):
def test_ctypes_cast(self):
# Issue 15944: Allow all source formats when casting to bytes.
ctypes = test.support.import_module("ctypes")
p6 = bytes(ctypes.c_double(0.6))
d = ctypes.c_double()
m = memoryview(d).cast("B")
m[:2] = p6[:2]
m[2:] = p6[2:]
self.assertEqual(d.value, 0.6)
for format in "Bbc":
with self.subTest(format):
d = ctypes.c_double()
m = memoryview(d).cast(format)
m[:2] = memoryview(p6).cast(format)[:2]
m[2:] = memoryview(p6).cast(format)[2:]
self.assertEqual(d.value, 0.6)
if __name__ == "__main__":
unittest.main()

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@ -98,6 +98,9 @@ Core and Builtins
- Issue #24687: Plug refleak on SyntaxError in function parameters
annotations.
- Issue #15944: memoryview: Allow arbitrary formats when casting to bytes.
Patch by Martin Panter.
Library
-------

View File

@ -1197,13 +1197,6 @@ cast_to_1D(PyMemoryViewObject *mv, PyObject *format)
assert(view->strides == mv->ob_array + view->ndim);
assert(view->suboffsets == mv->ob_array + 2*view->ndim);
if (get_native_fmtchar(&srcchar, view->format) < 0) {
PyErr_SetString(PyExc_ValueError,
"memoryview: source format must be a native single character "
"format prefixed with an optional '@'");
return ret;
}
asciifmt = PyUnicode_AsASCIIString(format);
if (asciifmt == NULL)
return ret;
@ -1216,7 +1209,8 @@ cast_to_1D(PyMemoryViewObject *mv, PyObject *format)
goto out;
}
if (!IS_BYTE_FORMAT(srcchar) && !IS_BYTE_FORMAT(destchar)) {
if ((get_native_fmtchar(&srcchar, view->format) < 0 ||
!IS_BYTE_FORMAT(srcchar)) && !IS_BYTE_FORMAT(destchar)) {
PyErr_SetString(PyExc_TypeError,
"memoryview: cannot cast between two non-byte formats");
goto out;