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gh-130167: Improve speed of difflib.IS_LINE_JUNK by replacing re #130170

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gh-130167: Improve speed of difflib.IS_LINE_JUNK by replacing re #130170

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8f2670d
Improve speed of difflib.IS_LINE_JUNK by replacing re
donBarbos Feb 16, 2025
0fae9c5
Update difflib.py
donBarbos Feb 16, 2025
352b4bc
Update difflib.py
donBarbos Feb 16, 2025
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Add backward compatibility
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64dff4a
Update difflib.py
donBarbos Feb 16, 2025
32337c3
Update Lib/difflib.py
donBarbos Feb 16, 2025
390b6e7
Update difflib.py
donBarbos Feb 17, 2025
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Back `iff` word
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Update difflib
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10 changes: 5 additions & 5 deletions Lib/difflib.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1038,11 +1038,9 @@ def _qformat(self, aline, bline, atags, btags):
# remaining is that perhaps it was really the case that " volatile"
# was inserted after "private". I can live with that <wink>.

import re

def IS_LINE_JUNK(line, pat=re.compile(r"\s*(?:#\s*)?$").match):
def IS_LINE_JUNK(line, pat=None):
r"""
Return True for ignorable line: iff `line` is blank or contains a single '#'.
Return True for ignorable line: if and only if `line` is blank or contains a single '#'.

Examples:

Expand All @@ -1054,6 +1052,9 @@ def IS_LINE_JUNK(line, pat=re.compile(r"\s*(?:#\s*)?$").match):
False
"""

if pat is None:
stripped = line.strip()
return stripped == '' or stripped == '#'
return pat(line) is not None

def IS_CHARACTER_JUNK(ch, ws=" \t"):
Expand Down Expand Up @@ -2027,7 +2028,6 @@ def make_table(self,fromlines,tolines,fromdesc='',todesc='',context=False,
replace('\1','</span>'). \
replace('\t','&nbsp;')

del re

def restore(delta, which):
r"""
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Library/2025-02-16-06-25-01.gh-issue-130167.kUg7Rc.rst
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@@ -0,0 +1,2 @@
Improve speed of :func:`difflib.IS_LINE_JUNK` by replacing :mod:`re` with
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Using re or built-in string methods is an implementation detail. This does not concern users and is not of interest to them.

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@donBarbos donBarbos Feb 17, 2025 •
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@serhiy-storchaka ok so should I remove NEWS.d entry or replace with something else. I just took as a sample news entries from PRs related to issue on improving importtime

built-in string methods.
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