histedit: pick an appropriate base changeset by default (BC)
Previously, `hg histedit` required a revision argument specifying which
revision to use as the base for the current histedit operation. There
was an undocumented and experimental "histedit.defaultrev" option that
supported defining a single revision to be used if no argument is
passed.
Mercurial knows what changesets can be edited. And in most scenarios,
people want to edit this history of everything on the current head that
is rewritable. Making histedit do this by default and not require
an explicit argument or additional configuration is a major usability
win and will enable more people to use histedit.
This patch changes the behavior of the experimental and undocumented
"histedit.defaultrev" config option to select an appropriate base
revision by default. Comprehensive tests exercising the edge cases
in the new, somewhat complicated default revset have been added.
Surprisingly, no tests broke. I guess we were never testing the
behavior with no ANCESTOR argument (it used to fail with
"abort: histedit requires exactly one ancestor revision"). The new
behavior is much more user friendly.
The functionality for choosing the default base revision has been
moved to destutil.py, where it can easily be modified by extensions.
# destutil.py - Mercurial utility function for command destination
#
# Copyright Matt Mackall <mpm@selenic.com> 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()
histeditdefaultrevset = 'reverse(only(.) and not public() and not ::merge())'
def desthistedit(ui, repo):
"""Default base revision to edit for `hg histedit`."""
default = ui.config('histedit', 'defaultrev', histeditdefaultrevset)
if default:
revs = repo.revs(default)
if revs:
# The revset supplied by the user may not be in ascending order nor
# take the first revision. So do this manually.
revs.sort()
return revs.first()
return None