encoding: fix trim() to be O(n) instead of O(n^2)
`encoding.trim()` iterated over the possible lengths smaller than the
input and created a slice for each. It then calculated the column
width of the result, which is of course O(n), so the overall algorithm
was O(n). This patch rewrites it to iterate over the unicode
characters, keeping track of the length so far. Also, the old
algorithm started from the end of the string, which made it much worse
when the input is large and the limit is small (such as the typical 72
we pass to it).
You can time it by running something like this:
```
time python3 -c 'from mercurial.utils import stringutil; print(stringutil.ellipsis(b"0123456789" * 1000, 5))'
```
That drops from 4.05 s to 83 ms with this patch (and most of that is
of course startup time).
Differential Revision: https://phab.mercurial-scm.org/D12089
Test character encoding
$ hg init t
$ cd t
we need a repo with some legacy latin-1 changesets
$ hg unbundle "$TESTDIR/bundles/legacy-encoding.hg"
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 1 files
new changesets 1e78a93102a3:0e5b7e3f9c4a (2 drafts)
(run 'hg update' to get a working copy)
$ hg co
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ "$PYTHON" << EOF
> f = open('latin-1', 'wb'); f.write(b"latin-1 e' encoded: \xe9"); f.close()
> f = open('utf-8', 'wb'); f.write(b"utf-8 e' encoded: \xc3\xa9"); f.close()
> f = open('latin-1-tag', 'wb'); f.write(b"\xe9"); f.close()
> EOF
should fail with encoding error
$ echo "plain old ascii" > a
$ hg st
M a
? latin-1
? latin-1-tag
? utf-8
$ HGENCODING=ascii hg ci -l latin-1
transaction abort!
rollback completed
abort: decoding near ' encoded: \xe9': 'ascii' codec can't decode byte 0xe9 in position 20: ordinal not in range(128)! (esc)
[255]
these should work
$ echo "latin-1" > a
$ HGENCODING=latin-1 hg ci -l latin-1
$ echo "utf-8" > a
$ HGENCODING=utf-8 hg ci -l utf-8
$ HGENCODING=latin-1 hg tag `cat latin-1-tag`
$ HGENCODING=latin-1 hg branch `cat latin-1-tag`
marked working directory as branch \xe9 (esc)
(branches are permanent and global, did you want a bookmark?)
$ HGENCODING=latin-1 hg ci -m 'latin1 branch'
$ hg -q rollback
$ HGENCODING=latin-1 hg branch
\xe9 (esc)
$ HGENCODING=latin-1 hg ci -m 'latin1 branch'
$ rm .hg/branch
hg log (ascii)
$ hg --encoding ascii log
changeset: 5:a52c0692f24a
branch: ?
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin1 branch
changeset: 4:94db611b4196
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag ? for changeset ca661e7520de
changeset: 3:ca661e7520de
tag: ?
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: utf-8 e' encoded: ?
changeset: 2:650c6f3d55dd
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin-1 e' encoded: ?
changeset: 1:0e5b7e3f9c4a
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: koi8-r: ????? = u'\u0440\u0442\u0443\u0442\u044c'
changeset: 0:1e78a93102a3
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: latin-1 e': ? = u'\xe9'
hg log (latin-1)
$ hg --encoding latin-1 log
changeset: 5:a52c0692f24a
branch: \xe9 (esc)
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin1 branch
changeset: 4:94db611b4196
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag \xe9 for changeset ca661e7520de (esc)
changeset: 3:ca661e7520de
tag: \xe9 (esc)
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: utf-8 e' encoded: \xe9 (esc)
changeset: 2:650c6f3d55dd
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin-1 e' encoded: \xe9 (esc)
changeset: 1:0e5b7e3f9c4a
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: koi8-r: \xd2\xd4\xd5\xd4\xd8 = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
changeset: 0:1e78a93102a3
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: latin-1 e': \xe9 = u'\\xe9' (esc)
hg log (utf-8)
$ hg --encoding utf-8 log
changeset: 5:a52c0692f24a
branch: \xc3\xa9 (esc)
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin1 branch
changeset: 4:94db611b4196
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag \xc3\xa9 for changeset ca661e7520de (esc)
changeset: 3:ca661e7520de
tag: \xc3\xa9 (esc)
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: utf-8 e' encoded: \xc3\xa9 (esc)
changeset: 2:650c6f3d55dd
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin-1 e' encoded: \xc3\xa9 (esc)
changeset: 1:0e5b7e3f9c4a
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: koi8-r: \xc3\x92\xc3\x94\xc3\x95\xc3\x94\xc3\x98 = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
changeset: 0:1e78a93102a3
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: latin-1 e': \xc3\xa9 = u'\\xe9' (esc)
hg tags (ascii)
$ HGENCODING=ascii hg tags
tip 5:a52c0692f24a
? 3:ca661e7520de
hg tags (latin-1)
$ HGENCODING=latin-1 hg tags
tip 5:a52c0692f24a
\xe9 3:ca661e7520de (esc)
hg tags (utf-8)
$ HGENCODING=utf-8 hg tags
tip 5:a52c0692f24a
\xc3\xa9 3:ca661e7520de (esc)
hg tags (JSON)
$ hg tags -Tjson
[
{
"node": "a52c0692f24ad921c0a31e1736e7635a8b23b670",
"rev": 5,
"tag": "tip",
"type": ""
},
{
"node": "ca661e7520dec3f5438a63590c350bebadb04989",
"rev": 3,
"tag": "\xc3\xa9", (esc)
"type": ""
}
]
hg branches (ascii)
$ HGENCODING=ascii hg branches
? 5:a52c0692f24a
default 4:94db611b4196 (inactive)
hg branches (latin-1)
$ HGENCODING=latin-1 hg branches
\xe9 5:a52c0692f24a (esc)
default 4:94db611b4196 (inactive)
hg branches (utf-8)
$ HGENCODING=utf-8 hg branches
\xc3\xa9 5:a52c0692f24a (esc)
default 4:94db611b4196 (inactive)
$ echo '[ui]' >> .hg/hgrc
$ echo 'fallbackencoding = koi8-r' >> .hg/hgrc
hg log (utf-8)
$ HGENCODING=utf-8 hg log
changeset: 5:a52c0692f24a
branch: \xc3\xa9 (esc)
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin1 branch
changeset: 4:94db611b4196
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: Added tag \xc3\xa9 for changeset ca661e7520de (esc)
changeset: 3:ca661e7520de
tag: \xc3\xa9 (esc)
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: utf-8 e' encoded: \xc3\xa9 (esc)
changeset: 2:650c6f3d55dd
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: latin-1 e' encoded: \xc3\xa9 (esc)
changeset: 1:0e5b7e3f9c4a
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: koi8-r: \xd1\x80\xd1\x82\xd1\x83\xd1\x82\xd1\x8c = u'\\u0440\\u0442\\u0443\\u0442\\u044c' (esc)
changeset: 0:1e78a93102a3
user: test
date: Mon Jan 12 13:46:40 1970 +0000
summary: latin-1 e': \xd0\x98 = u'\\xe9' (esc)
hg log (dolphin)
$ HGENCODING=dolphin hg log
abort: unknown encoding: dolphin
(please check your locale settings)
[255]
$ HGENCODING=ascii hg branch `cat latin-1-tag`
abort: decoding near '\xe9': 'ascii' codec can't decode byte 0xe9 in position 0: ordinal not in range(128)! (esc)
[255]
$ cp latin-1-tag .hg/branch
$ HGENCODING=latin-1 hg ci -m 'auto-promote legacy name'
Test roundtrip encoding of lookup tables when not using UTF-8 (issue2763)
$ HGENCODING=latin-1 hg up `cat latin-1-tag`
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ cd ..
Test roundtrip encoding/decoding of utf8b for generated data
#if hypothesis
>>> import hypothesishelpers
>>> from mercurial import encoding
>>> hypothesishelpers.roundtrips(hypothesishelpers.st.binary(),
... encoding.fromutf8b, encoding.toutf8b)
Round trip OK
#endif