mercurial/filelog.py

filemerge: add config knob to check capabilities of internal merge tools

For historical reason, Mercurial assumes capabilities of internal
merge tools as below while examining rules to decide merge tool,
regardless of actual capabilities of them.

    =============== ====== ========
    specified via   binary symlinks
    =============== ====== ========
    --tool          o      o
    HGMERGE         o      o
    merge-patterns  o (*)  x (*)
    ui.merge        x (*)  x (*)
    =============== ====== ========

This causes:

  - unintentional internal merge tool is chosen for binary files via
    merge-patterns section of configuration file

  - explicit configuration of internal merge tool for symlinks is
    ignored unintentionally

But on the other hand, simple "check capability strictly" might break
backward compatibility (e.g. existing merge automations), because it
changes the result of merge tool selection.

Therefore, this patch adds config knob "merge.strict-capability-check"
to control whether capabilities of internal merge tools should be
checked strictly or not.

If this configuration is true, capabilities of internal merge tools
are checked strictly in (*) cases above.

# filelog.py - file history class for mercurial
#
# Copyright 2005-2007 Matt Mackall <[e-mail]>
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

from . import (
    error,
    repository,
    revlog,
)
from .utils import (
    interfaceutil,
)

@interfaceutil.implementer(repository.ifilestorage)
class filelog(object):
    def __init__(self, opener, path):
        self._revlog = revlog.revlog(opener,
                                     '/'.join(('data', path + '.i')),
                                     censorable=True)
        # full name of the user visible file, relative to the repository root
        self.filename = path
        self.index = self._revlog.index
        self.version = self._revlog.version
        self.storedeltachains = self._revlog.storedeltachains
        self._generaldelta = self._revlog._generaldelta

    def __len__(self):
        return len(self._revlog)

    def __iter__(self):
        return self._revlog.__iter__()

    def revs(self, start=0, stop=None):
        return self._revlog.revs(start=start, stop=stop)

    def parents(self, node):
        return self._revlog.parents(node)

    def parentrevs(self, rev):
        return self._revlog.parentrevs(rev)

    def rev(self, node):
        return self._revlog.rev(node)

    def node(self, rev):
        return self._revlog.node(rev)

    def lookup(self, node):
        return self._revlog.lookup(node)

    def linkrev(self, rev):
        return self._revlog.linkrev(rev)

    def flags(self, rev):
        return self._revlog.flags(rev)

    def commonancestorsheads(self, node1, node2):
        return self._revlog.commonancestorsheads(node1, node2)

    def descendants(self, revs):
        return self._revlog.descendants(revs)

    def headrevs(self):
        return self._revlog.headrevs()

    def heads(self, start=None, stop=None):
        return self._revlog.heads(start, stop)

    def children(self, node):
        return self._revlog.children(node)

    def deltaparent(self, rev):
        return self._revlog.deltaparent(rev)

    def candelta(self, baserev, rev):
        return self._revlog.candelta(baserev, rev)

    def iscensored(self, rev):
        return self._revlog.iscensored(rev)

    def rawsize(self, rev):
        return self._revlog.rawsize(rev)

    def checkhash(self, text, node, p1=None, p2=None, rev=None):
        return self._revlog.checkhash(text, node, p1=p1, p2=p2, rev=rev)

    def revision(self, node, _df=None, raw=False):
        return self._revlog.revision(node, _df=_df, raw=raw)

    def revdiff(self, rev1, rev2):
        return self._revlog.revdiff(rev1, rev2)

    def addrevision(self, revisiondata, transaction, linkrev, p1, p2,
                    node=None, flags=revlog.REVIDX_DEFAULT_FLAGS,
                    cachedelta=None):
        return self._revlog.addrevision(revisiondata, transaction, linkrev,
                                    p1, p2, node=node, flags=flags,
                                    cachedelta=cachedelta)

    def addgroup(self, deltas, linkmapper, transaction, addrevisioncb=None):
        return self._revlog.addgroup(deltas, linkmapper, transaction,
                                 addrevisioncb=addrevisioncb)

    def getstrippoint(self, minlink):
        return self._revlog.getstrippoint(minlink)

    def strip(self, minlink, transaction):
        return self._revlog.strip(minlink, transaction)

    def files(self):
        return self._revlog.files()

    def checksize(self):
        return self._revlog.checksize()

    def read(self, node):
        t = self.revision(node)
        if not t.startswith('\1\n'):
            return t
        s = t.index('\1\n', 2)
        return t[s + 2:]

    def add(self, text, meta, transaction, link, p1=None, p2=None):
        if meta or text.startswith('\1\n'):
            text = revlog.packmeta(meta, text)
        return self.addrevision(text, transaction, link, p1, p2)

    def renamed(self, node):
        if self.parents(node)[0] != revlog.nullid:
            return False
        t = self.revision(node)
        m = revlog.parsemeta(t)[0]
        # copy and copyrev occur in pairs. In rare cases due to bugs,
        # one can occur without the other.
        if m and "copy" in m and "copyrev" in m:
            return (m["copy"], revlog.bin(m["copyrev"]))
        return False

    def size(self, rev):
        """return the size of a given revision"""

        # for revisions with renames, we have to go the slow way
        node = self.node(rev)
        if self.renamed(node):
            return len(self.read(node))
        if self.iscensored(rev):
            return 0

        # XXX if self.read(node).startswith("\1\n"), this returns (size+4)
        return self._revlog.size(rev)

    def cmp(self, node, text):
        """compare text with a given file revision

        returns True if text is different than what is stored.
        """

        t = text
        if text.startswith('\1\n'):
            t = '\1\n\1\n' + text

        samehashes = not self._revlog.cmp(node, t)
        if samehashes:
            return False

        # censored files compare against the empty file
        if self.iscensored(self.rev(node)):
            return text != ''

        # renaming a file produces a different hash, even if the data
        # remains unchanged. Check if it's the case (slow):
        if self.renamed(node):
            t2 = self.read(node)
            return t2 != text

        return True

    @property
    def filename(self):
        return self._revlog.filename

    @filename.setter
    def filename(self, value):
        self._revlog.filename = value

    # TODO these aren't part of the interface and aren't internal methods.
    # Callers should be fixed to not use them.
    @property
    def indexfile(self):
        return self._revlog.indexfile

    @indexfile.setter
    def indexfile(self, value):
        self._revlog.indexfile = value

    @property
    def datafile(self):
        return self._revlog.datafile

    @property
    def opener(self):
        return self._revlog.opener

    @property
    def _lazydeltabase(self):
        return self._revlog._lazydeltabase

    @_lazydeltabase.setter
    def _lazydeltabase(self, value):
        self._revlog._lazydeltabase = value

    @property
    def _deltabothparents(self):
        return self._revlog._deltabothparents

    @_deltabothparents.setter
    def _deltabothparents(self, value):
        self._revlog._deltabothparents = value

    @property
    def _inline(self):
        return self._revlog._inline

    @property
    def _withsparseread(self):
        return getattr(self._revlog, '_withsparseread', False)

    @property
    def _srmingapsize(self):
        return self._revlog._srmingapsize

    @property
    def _srdensitythreshold(self):
        return self._revlog._srdensitythreshold

    def _deltachain(self, rev, stoprev=None):
        return self._revlog._deltachain(rev, stoprev)

    def chainbase(self, rev):
        return self._revlog.chainbase(rev)

    def chainlen(self, rev):
        return self._revlog.chainlen(rev)

    def clone(self, tr, destrevlog, **kwargs):
        if not isinstance(destrevlog, filelog):
            raise error.ProgrammingError('expected filelog to clone()')

        return self._revlog.clone(tr, destrevlog._revlog, **kwargs)

    def start(self, rev):
        return self._revlog.start(rev)

    def end(self, rev):
        return self._revlog.end(rev)

    def length(self, rev):
        return self._revlog.length(rev)

    def compress(self, data):
        return self._revlog.compress(data)

    def _addrevision(self, *args, **kwargs):
        return self._revlog._addrevision(*args, **kwargs)