filemerge: add support for partial conflict resolution by external tool
A common class of merge conflicts is in imports/#includes/etc. It's
relatively easy to write a tool that can resolve these conflicts,
perhaps by naively just unioning the statements and leaving any
cleanup to other tools to do later [1]. Such specialized tools cannot
generally resolve all conflicts in a file, of course. Let's therefore
call them "partial merge tools". Note that the internal simplemerge
algorithm is such a partial merge tool - one that only resolves
trivial "conflicts" where one side is unchanged or both sides change
in the same way.
One can also imagine having smarter language-aware partial tools that
merge the AST. It may be useful for such tools to interactively let
the user resolve any conflicts it can't resolve itself. However,
having the option of implementing it as a partial merge tool means
that the developer doesn't *need* to create a UI for it. Instead, the
user can resolve any remaining conflicts with their regular merge tool
(e.g. `:merge3` or `meld).
We don't currently have a way to let the user define such partial
merge tools. That's what this patch addresses. It lets the user
configure partial merge tools to run. Each tool can be configured to
run only on files matching certain patterns (e.g. "*.py"). The tool
takes three inputs (local, base, other) and resolves conflicts by
updating these in place. For example, let's say the inputs are these:
base:
```
import sys
def main():
print('Hello')
```
local:
```
import os
import sys
def main():
print('Hi')
```
other:
```
import re
import sys
def main():
print('Howdy')
```
A partial merge tool could now resolve the conflicting imports by
replacing the import statements in *all* files by the following
snippet, while leaving the remainder of the files unchanged.
```
import os
import re
import sys
```
As a result, simplemerge and any regular merge tool that runs after
the partial merge tool(s) will consider the imports to be
non-conflicting and will only present the conflict in `main()` to the
user.
Differential Revision: https://phab.mercurial-scm.org/D12356
# i18n.py - internationalization support for mercurial
#
# Copyright 2005, 2006 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 gettext as gettextmod
import locale
import os
import sys
from .pycompat import getattr
from .utils import resourceutil
from . import (
encoding,
pycompat,
)
if pycompat.TYPE_CHECKING:
from typing import (
Callable,
List,
)
# modelled after templater.templatepath:
if getattr(sys, 'frozen', None) is not None:
module = pycompat.sysexecutable
else:
module = pycompat.fsencode(__file__)
_languages = None
if (
pycompat.iswindows
and b'LANGUAGE' not in encoding.environ
and b'LC_ALL' not in encoding.environ
and b'LC_MESSAGES' not in encoding.environ
and b'LANG' not in encoding.environ
):
# Try to detect UI language by "User Interface Language Management" API
# if no locale variables are set. Note that locale.getdefaultlocale()
# uses GetLocaleInfo(), which may be different from UI language.
# (See http://msdn.microsoft.com/en-us/library/dd374098(v=VS.85).aspx )
try:
import ctypes
# pytype: disable=module-attr
langid = ctypes.windll.kernel32.GetUserDefaultUILanguage()
# pytype: enable=module-attr
_languages = [locale.windows_locale[langid]]
except (ImportError, AttributeError, KeyError):
# ctypes not found or unknown langid
pass
datapath = pycompat.fsdecode(resourceutil.datapath)
localedir = os.path.join(datapath, 'locale')
t = gettextmod.translation('hg', localedir, _languages, fallback=True)
try:
_ugettext = t.ugettext # pytype: disable=attribute-error
except AttributeError:
_ugettext = t.gettext
_msgcache = {} # encoding: {message: translation}
def gettext(message):
# type: (bytes) -> bytes
"""Translate message.
The message is looked up in the catalog to get a Unicode string,
which is encoded in the local encoding before being returned.
Important: message is restricted to characters in the encoding
given by sys.getdefaultencoding() which is most likely 'ascii'.
"""
# If message is None, t.ugettext will return u'None' as the
# translation whereas our callers expect us to return None.
if message is None or not _ugettext:
return message
cache = _msgcache.setdefault(encoding.encoding, {})
if message not in cache:
if type(message) is str:
# goofy unicode docstrings in test
paragraphs = message.split(u'\n\n') # type: List[str]
else:
# should be ascii, but we have unicode docstrings in test, which
# are converted to utf-8 bytes on Python 3.
paragraphs = [p.decode("utf-8") for p in message.split(b'\n\n')]
# Be careful not to translate the empty string -- it holds the
# meta data of the .po file.
u = u'\n\n'.join([p and _ugettext(p) or u'' for p in paragraphs])
try:
# encoding.tolocal cannot be used since it will first try to
# decode the Unicode string. Calling u.decode(enc) really
# means u.encode(sys.getdefaultencoding()).decode(enc). Since
# the Python encoding defaults to 'ascii', this fails if the
# translated string use non-ASCII characters.
encodingstr = pycompat.sysstr(encoding.encoding)
cache[message] = u.encode(encodingstr, "replace")
except LookupError:
# An unknown encoding results in a LookupError.
cache[message] = message
return cache[message]
def _plain():
if (
b'HGPLAIN' not in encoding.environ
and b'HGPLAINEXCEPT' not in encoding.environ
):
return False
exceptions = encoding.environ.get(b'HGPLAINEXCEPT', b'').strip().split(b',')
return b'i18n' not in exceptions
if _plain():
_ = lambda message: message # type: Callable[[bytes], bytes]
else:
_ = gettext