FazBrowse GitHub Viewer | Trending |
URL:
| Home
Tools: [Download Repo ZIP]   [Original HTTPS Page]

gh-106865: Improve `difflib.find_longest_match` performance with cache by gaogaotiantian · Pull Request #106877 · python/cpython · GitHub

  1. python
  2. cpython

Repository navigation

gh-106865: Improve difflib.find_longest_match performance with cache #106877

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
gaogaotiantian wants to merge 2 commits into from
Conversation 4 Commits 2 Checks 0 Files changed
Closed

gh-106865: Improve difflib.find_longest_match performance with cache #106877

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
5f35b0d
Improve difflib performance with a cache
gaogaotiantian Jul 18, 2023
0396f81
📜🤖 Added by blurb_it.
blurb-it[bot] Jul 18, 2023
File filter

Filter by extension

Filter by extension .py  (1) .rst  (1) All 2 file types selected
Viewed files
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Unified
Split
Hide whitespace
Diff view
Unified
Split
Hide whitespace
32 changes: 23 additions & 9 deletions Lib/difflib.py
Show comments
View file
Open in desktop
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters
Show hidden characters
Original file line number Diff line number Diff line change
Expand Up @@ -371,20 +371,34 @@ def find_longest_match(self, alo=0, ahi=None, blo=0, bhi=None):
# junk-free match ending with a[i-1] and b[j]
j2len = {}
nothing = []
b2jcache = {}
for i in range(alo, ahi):
# look at all instances of a[i] in b; note that because
# b2j has no junk keys, the loop is skipped if a[i] is junk
j2lenget = j2len.get
newj2len = {}
for j in b2j.get(a[i], nothing):
# a[i] matches b[j]
if j < blo:
continue
if j >= bhi:
break
k = newj2len[j] = j2lenget(j-1, 0) + 1
if k > bestsize:
besti, bestj, bestsize = i-k+1, j-k+1, k
if a[i] not in b2jcache:
cache = []
for j in b2j.get(a[i], nothing):
# a[i] matches b[j]
if j < blo:
continue
if j >= bhi:
break
cache.append(j)
k = newj2len[j] = j2lenget(j-1, 0) + 1
if k > bestsize:
besti, bestj, bestsize = i-k+1, j-k+1, k
b2jcache[a[i]] = cache
else:
for j in b2jcache[a[i]]:
# a[i] matches b[j]
if j-1 in j2len:
k = newj2len[j] = j2len[j-1] + 1
if k > bestsize:
besti, bestj, bestsize = i-k+1, j-k+1, k
else:
k = 1
j2len = newj2len

# Extend the best by non-junk elements on each end. In particular,
Expand Down
1 change: 1 addition & 0 deletions Misc/NEWS.d/next/Library/2023-07-18-23-45-19.gh-issue-106865.dxO3Qr.rst
Show comments
View file
Open in desktop
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters. Learn more about bidirectional Unicode characters
Show hidden characters
Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
Improve performance of :func:`difflib.SequenceMatcher.find_longest_match` with a cache on hot path
Back | FazBrowse Home | New Git URL