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[3.13] gh-103925: Fix csv.Sniffer for a quoted field ending a CRLF line (GH-103926)#154330

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Merged
serhiy-storchaka merged 1 commit into from
Jul 21, 2026
Merged

[3.13] gh-103925: Fix csv.Sniffer for a quoted field ending a CRLF line (GH-103926) #154330

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8 changes: 4 additions & 4 deletions Lib/csv.py
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Original file line numberDiff line numberDiff line change
Expand Up@@ -283,10 +283,10 @@ def _guess_quote_and_delimiter(self, data, delimiters):
"""

matches = []
for restr in (r'(?P<delim>[^\w\n"\'])(?P<space> ?)(?P<quote>["\']).*?(?P=quote)(?P=delim)', # ,".*?",
r'(?:^|\n)(?P<quote>["\']).*?(?P=quote)(?P<delim>[^\w\n"\'])(?P<space> ?)', # ".*?",
r'(?P<delim>[^\w\n"\'])(?P<space> ?)(?P<quote>["\']).*?(?P=quote)(?:$|\n)', # ,".*?"
r'(?:^|\n)(?P<quote>["\']).*?(?P=quote)(?:$|\n)'): # ".*?" (no delim, no space)
for restr in (r'(?P<delim>[^\w\n"\'])(?P<space> ?)(?P<quote>["\']).*?(?P=quote)(?P=delim)', # ,".*?",
r'(?:^|\n)(?P<quote>["\']).*?(?P=quote)(?P<delim>[^\w\n"\'])(?P<space> ?)', # ".*?",
r'(?P<delim>[^\w\n"\'])(?P<space> ?)(?P<quote>["\']).*?(?P=quote)(?:$|\r|\n)', # ,".*?"
r'(?:^|\n)(?P<quote>["\']).*?(?P=quote)(?:$|\r|\n)'): # ".*?" (no delim, no space)
regexp = re.compile(restr, re.DOTALL | re.MULTILINE)
matches = regexp.findall(data)
if matches:
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6 changes: 6 additions & 0 deletions Lib/test/test_csv.py
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Original file line numberDiff line numberDiff line change
Expand Up@@ -1357,6 +1357,9 @@ class TestSniffer(unittest.TestCase):
ghi\0jkl
"""

sample19 = ('time,title\r\n'
'2020-10-01,"Pocket - Save news, videos, stories and more"\r\n')

def test_issue43625(self):
sniffer = csv.Sniffer()
self.assertTrue(sniffer.has_header(self.sample12))
Expand DownExpand Up@@ -1427,6 +1430,9 @@ def test_delimiters(self):
self.assertEqual(dialect.quotechar, "'")
dialect = sniffer.sniff(self.sample14)
self.assertEqual(dialect.delimiter, '\0')
dialect = sniffer.sniff(self.sample19)
self.assertEqual(dialect.delimiter, ',')
self.assertEqual(dialect.quotechar, '"')

def test_doublequote(self):
sniffer = csv.Sniffer()
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3 changes: 3 additions & 0 deletions Misc/NEWS.d/next/Library/2023-04-27-14-50-03.gh-issue-103925.khC-El.rst
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@@ -0,0 +1,3 @@
Fix :meth:`csv.Sniffer.sniff` for a sample with ``\r\n`` line endings in
which a quoted field ends a line: a letter could be detected as the
delimiter.
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