Mercurial > hg
view tests/test-custom-filters.t @ 36672:9e7b14caf67f
xdiff: remove patience and histogram diff algorithms
Patience diff is the normal diff algorithm, plus some greediness that
unconditionally matches common common unique lines. That means it is easy to
construct cases to let it generate suboptimal result, like:
```
open('a', 'w').write('\n'.join(list('a' + 'x' * 300 + 'u' + 'x' * 700 + 'a\n')))
open('b', 'w').write('\n'.join(list('b' + 'x' * 700 + 'u' + 'x' * 300 + 'b\n')))
```
Patience diff has been advertised as being able to generate better results for
some C code changes. However, the more scientific way to do that is the
indention heuristic [1].
Since patience diff could generate suboptimal result more easily and its
"better" diff feature could be replaced by the new indention heuristic, let's
just remove it and its variant histogram diff to simplify the code.
[1]: https://github.com/git/git/commit/433860f3d0beb0c6f205290bd16cda413148f098
Test Plan:
`gcc -fPIC *.c --shared -o xdiff.so` still builds.
Differential Revision: https://phab.mercurial-scm.org/D2573
author | Jun Wu <quark@fb.com> |
---|---|
date | Sat, 03 Mar 2018 10:39:55 -0800 |
parents | 56b2bcea2529 |
children | 6e713711331b |
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$ hg init $ cat > .hg/hgrc <<EOF > [extensions] > prefixfilter = prefix.py > [encode] > *.txt = stripprefix: Copyright 2046, The Masters > [decode] > *.txt = insertprefix: Copyright 2046, The Masters > EOF $ cat > prefix.py <<EOF > from mercurial import error > def stripprefix(s, cmd, filename, **kwargs): > header = '%s\n' % cmd > if s[:len(header)] != header: > raise error.Abort('missing header "%s" in %s' % (cmd, filename)) > return s[len(header):] > def insertprefix(s, cmd): > return '%s\n%s' % (cmd, s) > def reposetup(ui, repo): > repo.adddatafilter('stripprefix:', stripprefix) > repo.adddatafilter('insertprefix:', insertprefix) > EOF $ cat > .hgignore <<EOF > .hgignore > prefix.py > prefix.pyc > EOF $ cat > stuff.txt <<EOF > Copyright 2046, The Masters > Some stuff to ponder very carefully. > EOF $ hg add stuff.txt $ hg ci -m stuff Repository data: $ hg cat stuff.txt Some stuff to ponder very carefully. Fresh checkout: $ rm stuff.txt $ hg up -C 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cat stuff.txt Copyright 2046, The Masters Some stuff to ponder very carefully. $ echo "Very very carefully." >> stuff.txt $ hg stat M stuff.txt $ echo "Unauthorized material subject to destruction." > morestuff.txt Problem encoding: $ hg add morestuff.txt $ hg ci -m morestuff abort: missing header "Copyright 2046, The Masters" in morestuff.txt [255] $ hg stat M stuff.txt A morestuff.txt