[Python-checkins] Fix difflib `?` hint in diff output when dealing with tabs (GH-15201)
Miss Islington (bot)
webhook-mailer at python.org
Wed Aug 21 15:18:32 EDT 2019
https://github.com/python/cpython/commit/7e293f5e4c27592c6808bd7db13d7bd09dd7f5a0
commit: 7e293f5e4c27592c6808bd7db13d7bd09dd7f5a0
branch: 3.8
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2019-08-21T12:18:26-07:00
summary:
Fix difflib `?` hint in diff output when dealing with tabs (GH-15201)
(cherry picked from commit e1c638da6a065af6803028ced1afcc679e63f59d)
Co-authored-by: Anthony Sottile <asottile at umich.edu>
files:
A Misc/NEWS.d/next/Library/2019-08-10-12-33-27.bpo-37810.d4zbvB.rst
M Lib/difflib.py
M Lib/test/test_difflib.py
diff --git a/Lib/difflib.py b/Lib/difflib.py
index 887c3c26cae4..3de1b3d0fcdf 100644
--- a/Lib/difflib.py
+++ b/Lib/difflib.py
@@ -733,20 +733,15 @@ def get_close_matches(word, possibilities, n=3, cutoff=0.6):
# Strip scores for the best n matches
return [x for score, x in result]
-def _count_leading(line, ch):
- """
- Return number of `ch` characters at the start of `line`.
- Example:
+def _keep_original_ws(s, tag_s):
+ """Replace whitespace with the original whitespace characters in `s`"""
+ return ''.join(
+ c if tag_c == " " and c.isspace() else tag_c
+ for c, tag_c in zip(s, tag_s)
+ )
- >>> _count_leading(' abc', ' ')
- 3
- """
- i, n = 0, len(line)
- while i < n and line[i] == ch:
- i += 1
- return i
class Differ:
r"""
@@ -1033,7 +1028,7 @@ def _fancy_helper(self, a, alo, ahi, b, blo, bhi):
def _qformat(self, aline, bline, atags, btags):
r"""
- Format "?" output and deal with leading tabs.
+ Format "?" output and deal with tabs.
Example:
@@ -1047,22 +1042,16 @@ def _qformat(self, aline, bline, atags, btags):
'+ \tabcdefGhijkl\n'
'? \t ^ ^ ^\n'
"""
-
- # Can hurt, but will probably help most of the time.
- common = min(_count_leading(aline, "\t"),
- _count_leading(bline, "\t"))
- common = min(common, _count_leading(atags[:common], " "))
- common = min(common, _count_leading(btags[:common], " "))
- atags = atags[common:].rstrip()
- btags = btags[common:].rstrip()
+ atags = _keep_original_ws(aline, atags).rstrip()
+ btags = _keep_original_ws(bline, btags).rstrip()
yield "- " + aline
if atags:
- yield "? %s%s\n" % ("\t" * common, atags)
+ yield f"? {atags}\n"
yield "+ " + bline
if btags:
- yield "? %s%s\n" % ("\t" * common, btags)
+ yield f"? {btags}\n"
# With respect to junk, an earlier version of ndiff simply refused to
# *start* a match with a junk element. The result was cases like this:
diff --git a/Lib/test/test_difflib.py b/Lib/test/test_difflib.py
index 745ccbd6659e..5e2ca1a23b92 100644
--- a/Lib/test/test_difflib.py
+++ b/Lib/test/test_difflib.py
@@ -89,10 +89,16 @@ def test_added_tab_hint(self):
# Check fix for bug #1488943
diff = list(difflib.Differ().compare(["\tI am a buggy"],["\t\tI am a bug"]))
self.assertEqual("- \tI am a buggy", diff[0])
- self.assertEqual("? --\n", diff[1])
+ self.assertEqual("? \t --\n", diff[1])
self.assertEqual("+ \t\tI am a bug", diff[2])
self.assertEqual("? +\n", diff[3])
+ def test_hint_indented_properly_with_tabs(self):
+ diff = list(difflib.Differ().compare(["\t \t \t^"], ["\t \t \t^\n"]))
+ self.assertEqual("- \t \t \t^", diff[0])
+ self.assertEqual("+ \t \t \t^\n", diff[1])
+ self.assertEqual("? \t \t \t +\n", diff[2])
+
def test_mdiff_catch_stop_iteration(self):
# Issue #33224
self.assertEqual(
diff --git a/Misc/NEWS.d/next/Library/2019-08-10-12-33-27.bpo-37810.d4zbvB.rst b/Misc/NEWS.d/next/Library/2019-08-10-12-33-27.bpo-37810.d4zbvB.rst
new file mode 100644
index 000000000000..3e0b31775d07
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-08-10-12-33-27.bpo-37810.d4zbvB.rst
@@ -0,0 +1,2 @@
+Fix :mod:`difflib` ``?`` hint in diff output when dealing with tabs. Patch
+by Anthony Sottile.
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