mercurial/destutil.py

destupdate: extract logic based on obsolescence marker in its own function

One of the main goal of having consolidated destination function is to allow
extension to play with this logic. We extract sub logic to make is wrapping more
practical.

# destutil.py - Mercurial utility function for command destination
#
#  Copyright Matt Mackall <[e-mail]> and other
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.

from .i18n import _
from . import (
    bookmarks,
    error,
    obsolete,
)

def _destupdatevalidate(repo, rev, clean, check):
    """validate that the destination comply to various rules

    This exists as its own function to help wrapping from extensions."""
    wc = repo[None]
    p1 = wc.p1()
    if not clean:
        # Check that the update is linear.
        #
        # Mercurial do not allow update-merge for non linear pattern
        # (that would be technically possible but was considered too confusing
        # for user a long time ago)
        #
        # See mercurial.merge.update for details
        if p1.rev() not in repo.changelog.ancestors([rev], inclusive=True):
            dirty = wc.dirty(missing=True)
            foreground = obsolete.foreground(repo, [p1.node()])
            if not repo[rev].node() in foreground:
                if dirty:
                    msg = _("uncommitted changes")
                    hint = _("commit and merge, or update --clean to"
                             " discard changes")
                    raise error.UpdateAbort(msg, hint=hint)
                elif not check:  # destination is not a descendant.
                    msg = _("not a linear update")
                    hint = _("merge or update --check to force update")
                    raise error.UpdateAbort(msg, hint=hint)

def _destupdateobs(repo, clean, check):
    """decide of an update destination from obsolescence markers"""
    node = None
    wc = repo[None]
    p1 = wc.p1()
    movemark = None

    if p1.obsolete() and not p1.children():
        # allow updating to successors
        successors = obsolete.successorssets(repo, p1.node())

        # behavior of certain cases is as follows,
        #
        # divergent changesets: update to highest rev, similar to what
        #     is currently done when there are more than one head
        #     (i.e. 'tip')
        #
        # replaced changesets: same as divergent except we know there
        # is no conflict
        #
        # pruned changeset: no update is done; though, we could
        #     consider updating to the first non-obsolete parent,
        #     similar to what is current done for 'hg prune'

        if successors:
            # flatten the list here handles both divergent (len > 1)
            # and the usual case (len = 1)
            successors = [n for sub in successors for n in sub]

            # get the max revision for the given successors set,
            # i.e. the 'tip' of a set
            node = repo.revs('max(%ln)', successors).first()
            if bookmarks.isactivewdirparent(repo):
                movemark = repo['.'].node()
    return node, movemark, None

def destupdate(repo, clean=False, check=False):
    """destination for bare update operation

    return (rev, movemark, activemark)

    - rev: the revision to update to,
    - movemark: node to move the active bookmark from
                (cf bookmark.calculate update),
    - activemark: a bookmark to activate at the end of the update.
    """
    node = None
    wc = repo[None]
    movemark = activemark = None

    node, movemark, activemark = _destupdateobs(repo, clean, check)

    if node is None:
        # we also move the active bookmark, if any
        node, movemark = bookmarks.calculateupdate(repo.ui, repo, None)
        if node is not None:
            activemark = node

        if node is None:
            try:
                node = repo.branchtip(wc.branch())
            except error.RepoLookupError:
                if wc.branch() == 'default': # no default branch!
                    node = repo.lookup('tip') # update to tip
                else:
                    raise error.Abort(_("branch %s not found") % wc.branch())
    rev = repo[node].rev()

    _destupdatevalidate(repo, rev, clean, check)

    return rev, movemark, activemark

def destmerge(repo):
    if repo._activebookmark:
        bmheads = repo.bookmarkheads(repo._activebookmark)
        curhead = repo[repo._activebookmark].node()
        if len(bmheads) == 2:
            if curhead == bmheads[0]:
                node = bmheads[1]
            else:
                node = bmheads[0]
        elif len(bmheads) > 2:
            raise error.Abort(_("multiple matching bookmarks to merge - "
                "please merge with an explicit rev or bookmark"),
                hint=_("run 'hg heads' to see all heads"))
        elif len(bmheads) <= 1:
            raise error.Abort(_("no matching bookmark to merge - "
                "please merge with an explicit rev or bookmark"),
                hint=_("run 'hg heads' to see all heads"))
    else:
        branch = repo[None].branch()
        bheads = repo.branchheads(branch)
        nbhs = [bh for bh in bheads if not repo[bh].bookmarks()]

        if len(nbhs) > 2:
            raise error.Abort(_("branch '%s' has %d heads - "
                               "please merge with an explicit rev")
                             % (branch, len(bheads)),
                             hint=_("run 'hg heads .' to see heads"))

        parent = repo.dirstate.p1()
        if len(nbhs) <= 1:
            if len(bheads) > 1:
                raise error.Abort(_("heads are bookmarked - "
                                   "please merge with an explicit rev"),
                                 hint=_("run 'hg heads' to see all heads"))
            if len(repo.heads()) > 1:
                raise error.Abort(_("branch '%s' has one head - "
                                   "please merge with an explicit rev")
                                 % branch,
                                 hint=_("run 'hg heads' to see all heads"))
            msg, hint = _('nothing to merge'), None
            if parent != repo.lookup(branch):
                hint = _("use 'hg update' instead")
            raise error.Abort(msg, hint=hint)

        if parent not in bheads:
            raise error.Abort(_('working directory not at a head revision'),
                             hint=_("use 'hg update' or merge with an "
                                    "explicit revision"))
        if parent == nbhs[0]:
            node = nbhs[-1]
        else:
            node = nbhs[0]
    return repo[node].rev()