view mercurial/destutil.py @ 27085:d50ff8f4891f

histedit: add an experimental base action

This is a first (very simple) version of the histedit base action.
It works well in common usecases like rebasing the whole stack and
spliting the stack.

I don't see any obvious edge cases - but probably there is more than one.
That's why I want to keep it behind experimental.histeditng config knob
for now. I think on knob for all new histedit behaviors is better because
we will test all of them together and testers will need to turn it on only
once to get all new nice things.

# 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 _destupdatebook(repo, clean, check):
    """decide on an update destination from active bookmark"""
    # we also move the active bookmark, if any
    activemark = None
    node, movemark = bookmarks.calculateupdate(repo.ui, repo, None)
    if node is not None:
        activemark = node
    return node, movemark, activemark

def _destupdatebranch(repo, clean, check):
    """decide on an update destination from current branch"""
    wc = repo[None]
    movemark = node = None
    try:
        node = repo.branchtip(wc.branch())
        if bookmarks.isactivewdirparent(repo):
            movemark = repo['.'].node()
    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())
    return node, movemark, None

# order in which each step should be evalutated
# steps are run until one finds a destination
destupdatesteps = ['evolution', 'bookmark', 'branch']
# mapping to ease extension overriding steps.
destupdatestepmap = {'evolution': _destupdateobs,
                     'bookmark': _destupdatebook,
                     'branch': _destupdatebranch,
                     }

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 = movemark = activemark = None

    for step in destupdatesteps:
        node, movemark, activemark = destupdatestepmap[step](repo, clean, check)
        if node is not None:
            break
    rev = repo[node].rev()

    _destupdatevalidate(repo, rev, clean, check)

    return rev, movemark, activemark

def _destmergebook(repo):
    """find merge destination in the active bookmark case"""
    node = None
    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"))
    assert node is not None
    return node

def _destmergebranch(repo):
    """find merge destination based on branch heads"""
    node = None
    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]
    assert node is not None
    return node

def destmerge(repo):
    if repo._activebookmark:
        node = _destmergebook(repo)
    else:
        node = _destmergebranch(repo)
    return repo[node].rev()