Issue #21827: Fixed textwrap.dedent() for the case when largest common
whitespace is a substring of smallest leading whitespace.
Based on patch by Robert Li.
diff --git a/Lib/test/test_textwrap.py b/Lib/test/test_textwrap.py
index 7b72672..dccf095 100644
--- a/Lib/test/test_textwrap.py
+++ b/Lib/test/test_textwrap.py
@@ -647,6 +647,11 @@
expect = "hello there\n how are you?"
self.assertEqual(expect, dedent(text))
+ # test margin is smaller than smallest indent
+ text = " \thello there\n \thow are you?\n \tI'm fine, thanks"
+ expect = " \thello there\n \thow are you?\n\tI'm fine, thanks"
+ self.assertEqual(expect, dedent(text))
+
def test_main():
test_support.run_unittest(WrapTestCase,
diff --git a/Lib/textwrap.py b/Lib/textwrap.py
index e755860..5c2e4fa 100644
--- a/Lib/textwrap.py
+++ b/Lib/textwrap.py
@@ -403,11 +403,15 @@
elif margin.startswith(indent):
margin = indent
- # Current line and previous winner have no common whitespace:
- # there is no margin.
+ # Find the largest common whitespace between current line and previous
+ # winner.
else:
- margin = ""
- break
+ for i, (x, y) in enumerate(zip(margin, indent)):
+ if x != y:
+ margin = margin[:i]
+ break
+ else:
+ margin = margin[:len(indent)]
# sanity check (testing/debugging only)
if 0 and margin: