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bpo-40596: Fix str.isidentifier() for non-canonicalized strings containing non-BMP characters on Windows. #20053

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May 12, 2020
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7 changes: 7 additions & 0 deletions Lib/test/test_unicode.py
Original file line number Diff line number Diff line change
Expand Up @@ -720,6 +720,13 @@ def test_isidentifier(self):
self.assertFalse("©".isidentifier())
self.assertFalse("0".isidentifier())

@support.cpython_only
def test_isidentifier_legacy(self):
import _testcapi
u = '𝖀𝖓𝖎𝖈𝖔𝖉𝖊'
self.assertTrue(u.isidentifier())
self.assertTrue(_testcapi.unicode_legacy_string(u).isidentifier())

def test_isprintable(self):
self.assertTrue("".isprintable())
self.assertTrue(" ".isprintable())
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Fixed :meth:`str.isidentifier` for non-canonicalized strings containing
non-BMP characters on Windows.
26 changes: 22 additions & 4 deletions Objects/unicodeobject.c
Original file line number Diff line number Diff line change
Expand Up @@ -12356,20 +12356,38 @@ PyUnicode_IsIdentifier(PyObject *self)
return len && i == len;
}
else {
Py_ssize_t i, len = PyUnicode_GET_SIZE(self);
Py_ssize_t i = 0, len = PyUnicode_GET_SIZE(self);
if (len == 0) {
/* an empty string is not a valid identifier */
return 0;
}

const wchar_t *wstr = _PyUnicode_WSTR(self);
Py_UCS4 ch = wstr[0];
Py_UCS4 ch = wstr[i++];
#if SIZEOF_WCHAR_T == 2
if (Py_UNICODE_IS_HIGH_SURROGATE(ch)
&& i < len
&& Py_UNICODE_IS_LOW_SURROGATE(wstr[i]))
{
ch = Py_UNICODE_JOIN_SURROGATES(ch, wstr[i]);
i++;
}
#endif
if (!_PyUnicode_IsXidStart(ch) && ch != 0x5F /* LOW LINE */) {
return 0;
}

for (i = 1; i < len; i++) {
ch = wstr[i];
while (i < len) {
ch = wstr[i++];
#if SIZEOF_WCHAR_T == 2
if (Py_UNICODE_IS_HIGH_SURROGATE(ch)
&& i < len
&& Py_UNICODE_IS_LOW_SURROGATE(wstr[i]))
{
ch = Py_UNICODE_JOIN_SURROGATES(ch, wstr[i]);
i++;
}
#endif
if (!_PyUnicode_IsXidContinue(ch)) {
return 0;
}
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