templates: add filter to reverse list
The filter supports only lists because for lists, it’s straightforward to
implement. Reversing text doesn’t seem very useful and is hard to implement.
Reversing the bytes would break multi-bytes encodings. Reversing the code
points would break characters consisting of multiple code points. Reversing
graphemes is non-trivial without using a library not included in the standard
library.
$ 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 = b'%s\n' % cmd
> if s[:len(header)] != header:
> raise error.Abort(b'missing header "%s" in %s' % (cmd, filename))
> return s[len(header):]
> def insertprefix(s, cmd):
> return b'%s\n%s' % (cmd, s)
> def reposetup(ui, repo):
> repo.adddatafilter(b'stripprefix:', stripprefix)
> repo.adddatafilter(b'insertprefix:', insertprefix)
> EOF
$ cat > .hgignore <<EOF
> .hgignore
> prefix.py
> prefix.pyc
> __pycache__/
> 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