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.
# dirstateguard.py - class to allow restoring dirstate after failure
#
# Copyright 2005-2007 Olivia Mackall <olivia@selenic.com>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import os
from .i18n import _
from . import (
error,
narrowspec,
requirements,
util,
)
class dirstateguard(util.transactional):
"""Restore dirstate at unexpected failure.
At the construction, this class does:
- write current ``repo.dirstate`` out, and
- save ``.hg/dirstate`` into the backup file
This restores ``.hg/dirstate`` from backup file, if ``release()``
is invoked before ``close()``.
This just removes the backup file at ``close()`` before ``release()``.
"""
def __init__(self, repo, name):
self._repo = repo
self._active = False
self._closed = False
def getname(prefix):
fd, fname = repo.vfs.mkstemp(prefix=prefix)
os.close(fd)
return fname
self._backupname = getname(b'dirstate.backup.%s.' % name)
repo.dirstate.savebackup(repo.currenttransaction(), self._backupname)
# Don't make this the empty string, things may join it with stuff and
# blindly try to unlink it, which could be bad.
self._narrowspecbackupname = None
if requirements.NARROW_REQUIREMENT in repo.requirements:
self._narrowspecbackupname = getname(
b'narrowspec.backup.%s.' % name
)
narrowspec.savewcbackup(repo, self._narrowspecbackupname)
self._active = True
def __del__(self):
if self._active: # still active
# this may occur, even if this class is used correctly:
# for example, releasing other resources like transaction
# may raise exception before ``dirstateguard.release`` in
# ``release(tr, ....)``.
self._abort()
def close(self):
if not self._active: # already inactivated
msg = (
_(b"can't close already inactivated backup: %s")
% self._backupname
)
raise error.Abort(msg)
self._repo.dirstate.clearbackup(
self._repo.currenttransaction(), self._backupname
)
if self._narrowspecbackupname:
narrowspec.clearwcbackup(self._repo, self._narrowspecbackupname)
self._active = False
self._closed = True
def _abort(self):
if self._narrowspecbackupname:
narrowspec.restorewcbackup(self._repo, self._narrowspecbackupname)
self._repo.dirstate.restorebackup(
self._repo.currenttransaction(), self._backupname
)
self._active = False
def release(self):
if not self._closed:
if not self._active: # already inactivated
msg = (
_(b"can't release already inactivated backup: %s")
% self._backupname
)
raise error.Abort(msg)
self._abort()