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
# config.py - configuration parsing for Mercurial
#
# Copyright 2009 Olivia Mackall <olivia@selenic.com> and others
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import errno
import os
from .i18n import _
from .pycompat import getattr
from . import (
encoding,
error,
util,
)
class config:
def __init__(self, data=None):
self._current_source_level = 0
self._data = {}
self._unset = []
if data:
for k in data._data:
self._data[k] = data[k].copy()
self._current_source_level = data._current_source_level + 1
def new_source(self):
"""increment the source counter
This is used to define source priority when reading"""
self._current_source_level += 1
def copy(self):
return config(self)
def __contains__(self, section):
return section in self._data
def hasitem(self, section, item):
return item in self._data.get(section, {})
def __getitem__(self, section):
return self._data.get(section, {})
def __iter__(self):
for d in self.sections():
yield d
def update(self, src):
current_level = self._current_source_level
current_level += 1
max_level = self._current_source_level
for s, n in src._unset:
ds = self._data.get(s, None)
if ds is not None and n in ds:
self._data[s] = ds.preparewrite()
del self._data[s][n]
for s in src:
ds = self._data.get(s, None)
if ds:
self._data[s] = ds.preparewrite()
else:
self._data[s] = util.cowsortdict()
for k, v in src._data[s].items():
value, source, level = v
level += current_level
max_level = max(level, current_level)
self._data[s][k] = (value, source, level)
self._current_source_level = max_level
def _get(self, section, item):
return self._data.get(section, {}).get(item)
def get(self, section, item, default=None):
result = self._get(section, item)
if result is None:
return default
return result[0]
def backup(self, section, key):
"""return a tuple allowing restore to reinstall a previous value
The main reason we need it is because it handles the "no data" case.
"""
try:
item = self._data[section][key]
except KeyError:
return (section, key)
else:
return (section, key) + item
def source(self, section, item):
result = self._get(section, item)
if result is None:
return b""
return result[1]
def level(self, section, item):
result = self._get(section, item)
if result is None:
return None
return result[2]
def sections(self):
return sorted(self._data.keys())
def items(self, section):
items = self._data.get(section, {}).items()
return [(k, v[0]) for (k, v) in items]
def set(self, section, item, value, source=b""):
assert not isinstance(
section, str
), b'config section may not be unicode strings on Python 3'
assert not isinstance(
item, str
), b'config item may not be unicode strings on Python 3'
assert not isinstance(
value, str
), b'config values may not be unicode strings on Python 3'
if section not in self:
self._data[section] = util.cowsortdict()
else:
self._data[section] = self._data[section].preparewrite()
self._data[section][item] = (value, source, self._current_source_level)
def alter(self, section, key, new_value):
"""alter a value without altering its source or level
This method is meant to be used by `ui.fixconfig` only."""
item = self._data[section][key]
size = len(item)
new_item = (new_value,) + item[1:]
assert len(new_item) == size
self._data[section][key] = new_item
def restore(self, data):
"""restore data returned by self.backup"""
if len(data) != 2:
# restore old data
section, key = data[:2]
item = data[2:]
self._data[section] = self._data[section].preparewrite()
self._data[section][key] = item
else:
# no data before, remove everything
section, item = data
if section in self._data:
self._data[section].pop(item, None)
def parse(self, src, data, sections=None, remap=None, include=None):
sectionre = util.re.compile(br'\[([^\[]+)\]')
itemre = util.re.compile(br'([^=\s][^=]*?)\s*=\s*(.*\S|)')
contre = util.re.compile(br'\s+(\S|\S.*\S)\s*$')
emptyre = util.re.compile(br'(;|#|\s*$)')
commentre = util.re.compile(br'(;|#)')
unsetre = util.re.compile(br'%unset\s+(\S+)')
includere = util.re.compile(br'%include\s+(\S|\S.*\S)\s*$')
section = b""
item = None
line = 0
cont = False
if remap:
section = remap.get(section, section)
for l in data.splitlines(True):
line += 1
if line == 1 and l.startswith(b'\xef\xbb\xbf'):
# Someone set us up the BOM
l = l[3:]
if cont:
if commentre.match(l):
continue
m = contre.match(l)
if m:
if sections and section not in sections:
continue
v = self.get(section, item) + b"\n" + m.group(1)
self.set(section, item, v, b"%s:%d" % (src, line))
continue
item = None
cont = False
m = includere.match(l)
if m and include:
expanded = util.expandpath(m.group(1))
try:
include(expanded, remap=remap, sections=sections)
except IOError as inst:
if inst.errno != errno.ENOENT:
raise error.ConfigError(
_(b"cannot include %s (%s)")
% (expanded, encoding.strtolocal(inst.strerror)),
b"%s:%d" % (src, line),
)
continue
if emptyre.match(l):
continue
m = sectionre.match(l)
if m:
section = m.group(1)
if remap:
section = remap.get(section, section)
if section not in self:
self._data[section] = util.cowsortdict()
continue
m = itemre.match(l)
if m:
item = m.group(1)
cont = True
if sections and section not in sections:
continue
self.set(section, item, m.group(2), b"%s:%d" % (src, line))
continue
m = unsetre.match(l)
if m:
name = m.group(1)
if sections and section not in sections:
continue
if self.get(section, name) is not None:
self._data[section] = self._data[section].preparewrite()
del self._data[section][name]
self._unset.append((section, name))
continue
message = l.rstrip()
if l.startswith(b' '):
message = b"unexpected leading whitespace: %s" % message
raise error.ConfigError(message, (b"%s:%d" % (src, line)))
def read(self, path, fp=None, sections=None, remap=None):
self.new_source()
if not fp:
fp = util.posixfile(path, b'rb')
assert (
getattr(fp, 'mode', 'rb') == 'rb'
), b'config files must be opened in binary mode, got fp=%r mode=%r' % (
fp,
fp.mode,
)
dir = os.path.dirname(path)
def include(rel, remap, sections):
abs = os.path.normpath(os.path.join(dir, rel))
self.read(abs, remap=remap, sections=sections)
# anything after the include has a higher level
self.new_source()
self.parse(
path, fp.read(), sections=sections, remap=remap, include=include
)