annotate mercurial/destutil.py @ 33199:c5a07a3abe7d

show: implement "stack" view

People often want to know what they are working on *now*. As part of
this, they also commonly want to know how that work is related to other
changesets in the repo so they can perform common actions like rebase,
histedit, and merge.

`hg show work` made headway into this space. However, it is geared
towards a complete repo view as opposed to just the current line of
work. If you have a lot of in-flight work or the repo has many heads,
the output can be overwhelming. The closest thing Mercurial has to
"show me the current thing I'm working on" that doesn't require custom
revsets is `hg qseries`. And this requires MQ, which completely changes
workflows and repository behavior and has horrible performance on large
repos. But as sub-optimal as MQ is, it does some things right, such as
expose a model of the repo that is easy for people to reason about.
This simplicity is why I think a lot of people prefer to use MQ, despite
its shortcomings.

One common development workflow is to author a series of linear
changesets, using bookmarks, branches, anonymous heads, or even topics
(3rd party extension). I'll call this a "stack." You periodically
rewrite history in place (using `hg histedit`) and reparent the stack
against newer changesets (using `hg rebase`). This workflow can be
difficult because there is no obvious way to quickly see the current
"stack" nor its relation to other changesets. Figuring out arguments to
`hg rebase` can be difficult and may require highlighting and pasting
multiple changeset nodes to construct a command.

The goal of this commit is to make stack based workflows simpler
by exposing a view of the current stack and its relationship to
other releant changesets, notably the parent of the base changeset
in the stack and newer heads that the stack could be rebased or merged
into.

Introduced is the `hg show stack` view. Essentially, it finds all
mutable changesets from the working directory revision in both
directions, stopping at a merge or branch point. This limits the
revisions to a DAG linear range.

The stack is rendered as a concise list of changesets. Alongside the
stack is a visualization of the DAG, similar to `hg log -G`.

Newer public heads from the branch point of the stack are rendered
above the stack. The presence of these heads helps people understand
the DAG model and the relationship between the stack and changes made
since the branch point of that stack. If the "rebase" command is
available, a `hg rebase` command is printed for each head so a user
can perform a simple copy and paste to perform a rebase.

This view is alpha quality. There are tons of TODOs documented
inline. But I think it is good enough for a first iteration.

# 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 __future__ import absolute_import

from .i18n import _
from . import (
    bookmarks,
    error,
    obsutil,
    scmutil,
)

def _destupdateobs(repo, clean):
    """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 = obsutil.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):
    """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):
    """decide on an update destination from current branch

    This ignores closed branch heads.
    """
    wc = repo[None]
    movemark = node = None
    currentbranch = wc.branch()

    if clean:
        currentbranch = repo['.'].branch()

    if currentbranch in repo.branchmap():
        heads = repo.branchheads(currentbranch)
        if heads:
            node = repo.revs('max(.::(%ln))', heads).first()
        if bookmarks.isactivewdirparent(repo):
            movemark = repo['.'].node()
    elif currentbranch == 'default' and not wc.p1():
        # "null" parent belongs to "default" branch, but it doesn't exist, so
        # update to the tipmost non-closed branch head
        node = repo.revs('max(head() and not closed())').first()
    else:
        node = repo['.'].node()
    return node, movemark, None

def _destupdatebranchfallback(repo, clean):
    """decide on an update destination from closed heads in current branch"""
    wc = repo[None]
    currentbranch = wc.branch()
    movemark = None
    if currentbranch in repo.branchmap():
        # here, all descendant branch heads are closed
        heads = repo.branchheads(currentbranch, closed=True)
        assert heads, "any branch has at least one head"
        node = repo.revs('max(.::(%ln))', heads).first()
        assert node is not None, ("any revision has at least "
                                  "one descendant branch head")
        if bookmarks.isactivewdirparent(repo):
            movemark = repo['.'].node()
    else:
        # here, no "default" branch, and all branches are closed
        node = repo.lookup('tip')
        assert node is not None, "'tip' exists even in empty repository"
    return node, movemark, None

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

def destupdate(repo, clean=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)
        if node is not None:
            break
    rev = repo[node].rev()

    return rev, movemark, activemark

msgdestmerge = {
    # too many matching divergent bookmark
    'toomanybookmarks':
        {'merge':
            (_("multiple matching bookmarks to merge -"
               " please merge with an explicit rev or bookmark"),
             _("run 'hg heads' to see all heads")),
         'rebase':
            (_("multiple matching bookmarks to rebase -"
               " please rebase to an explicit rev or bookmark"),
             _("run 'hg heads' to see all heads")),
        },
    # no other matching divergent bookmark
    'nootherbookmarks':
        {'merge':
            (_("no matching bookmark to merge - "
               "please merge with an explicit rev or bookmark"),
             _("run 'hg heads' to see all heads")),
         'rebase':
            (_("no matching bookmark to rebase - "
               "please rebase to an explicit rev or bookmark"),
             _("run 'hg heads' to see all heads")),
        },
    # branch have too many unbookmarked heads, no obvious destination
    'toomanyheads':
        {'merge':
            (_("branch '%s' has %d heads - please merge with an explicit rev"),
             _("run 'hg heads .' to see heads")),
         'rebase':
            (_("branch '%s' has %d heads - please rebase to an explicit rev"),
             _("run 'hg heads .' to see heads")),
        },
    # branch have no other unbookmarked heads
    'bookmarkedheads':
        {'merge':
            (_("heads are bookmarked - please merge with an explicit rev"),
             _("run 'hg heads' to see all heads")),
         'rebase':
            (_("heads are bookmarked - please rebase to an explicit rev"),
             _("run 'hg heads' to see all heads")),
        },
    # branch have just a single heads, but there is other branches
    'nootherbranchheads':
        {'merge':
            (_("branch '%s' has one head - please merge with an explicit rev"),
             _("run 'hg heads' to see all heads")),
         'rebase':
            (_("branch '%s' has one head - please rebase to an explicit rev"),
             _("run 'hg heads' to see all heads")),
        },
    # repository have a single head
    'nootherheads':
        {'merge':
            (_('nothing to merge'),
            None),
         'rebase':
            (_('nothing to rebase'),
            None),
        },
    # repository have a single head and we are not on it
    'nootherheadsbehind':
        {'merge':
            (_('nothing to merge'),
             _("use 'hg update' instead")),
         'rebase':
            (_('nothing to rebase'),
             _("use 'hg update' instead")),
        },
    # We are not on a head
    'notatheads':
        {'merge':
            (_('working directory not at a head revision'),
             _("use 'hg update' or merge with an explicit revision")),
         'rebase':
            (_('working directory not at a head revision'),
             _("use 'hg update' or rebase to an explicit revision"))
        },
    'emptysourceset':
        {'merge':
            (_('source set is empty'),
             None),
         'rebase':
            (_('source set is empty'),
             None),
        },
    'multiplebranchessourceset':
        {'merge':
            (_('source set is rooted in multiple branches'),
             None),
         'rebase':
            (_('rebaseset is rooted in multiple named branches'),
             _('specify an explicit destination with --dest')),
        },
    }

def _destmergebook(repo, action='merge', sourceset=None, destspace=None):
    """find merge destination in the active bookmark case"""
    node = None
    bmheads = bookmarks.headsforactive(repo)
    curhead = repo[repo._activebookmark].node()
    if len(bmheads) == 2:
        if curhead == bmheads[0]:
            node = bmheads[1]
        else:
            node = bmheads[0]
    elif len(bmheads) > 2:
        msg, hint = msgdestmerge['toomanybookmarks'][action]
        raise error.ManyMergeDestAbort(msg, hint=hint)
    elif len(bmheads) <= 1:
        msg, hint = msgdestmerge['nootherbookmarks'][action]
        raise error.NoMergeDestAbort(msg, hint=hint)
    assert node is not None
    return node

def _destmergebranch(repo, action='merge', sourceset=None, onheadcheck=True,
                     destspace=None):
    """find merge destination based on branch heads"""
    node = None

    if sourceset is None:
        sourceset = [repo[repo.dirstate.p1()].rev()]
        branch = repo.dirstate.branch()
    elif not sourceset:
        msg, hint = msgdestmerge['emptysourceset'][action]
        raise error.NoMergeDestAbort(msg, hint=hint)
    else:
        branch = None
        for ctx in repo.set('roots(%ld::%ld)', sourceset, sourceset):
            if branch is not None and ctx.branch() != branch:
                msg, hint = msgdestmerge['multiplebranchessourceset'][action]
                raise error.ManyMergeDestAbort(msg, hint=hint)
            branch = ctx.branch()

    bheads = repo.branchheads(branch)
    onhead = repo.revs('%ld and %ln', sourceset, bheads)
    if onheadcheck and not onhead:
        # Case A: working copy if not on a head. (merge only)
        #
        # This is probably a user mistake We bailout pointing at 'hg update'
        if len(repo.heads()) <= 1:
            msg, hint = msgdestmerge['nootherheadsbehind'][action]
        else:
            msg, hint = msgdestmerge['notatheads'][action]
        raise error.Abort(msg, hint=hint)
    # remove heads descendants of source from the set
    bheads = list(repo.revs('%ln - (%ld::)', bheads, sourceset))
    # filters out bookmarked heads
    nbhs = list(repo.revs('%ld - bookmark()', bheads))

    if destspace is not None:
        # restrict search space
        # used in the 'hg pull --rebase' case, see issue 5214.
        nbhs = list(repo.revs('%ld and %ld', destspace, nbhs))

    if len(nbhs) > 1:
        # Case B: There is more than 1 other anonymous heads
        #
        # This means that there will be more than 1 candidate. This is
        # ambiguous. We abort asking the user to pick as explicit destination
        # instead.
        msg, hint = msgdestmerge['toomanyheads'][action]
        msg %= (branch, len(bheads) + 1)
        raise error.ManyMergeDestAbort(msg, hint=hint)
    elif not nbhs:
        # Case B: There is no other anonymous heads
        #
        # This means that there is no natural candidate to merge with.
        # We abort, with various messages for various cases.
        if bheads:
            msg, hint = msgdestmerge['bookmarkedheads'][action]
        elif len(repo.heads()) > 1:
            msg, hint = msgdestmerge['nootherbranchheads'][action]
            msg %= branch
        elif not onhead:
            # if 'onheadcheck == False' (rebase case),
            # this was not caught in Case A.
            msg, hint = msgdestmerge['nootherheadsbehind'][action]
        else:
            msg, hint = msgdestmerge['nootherheads'][action]
        raise error.NoMergeDestAbort(msg, hint=hint)
    else:
        node = nbhs[0]
    assert node is not None
    return node

def destmerge(repo, action='merge', sourceset=None, onheadcheck=True,
              destspace=None):
    """return the default destination for a merge

    (or raise exception about why it can't pick one)

    :action: the action being performed, controls emitted error message
    """
    # destspace is here to work around issues with `hg pull --rebase` see
    # issue5214 for details
    if repo._activebookmark:
        node = _destmergebook(repo, action=action, sourceset=sourceset,
                              destspace=destspace)
    else:
        node = _destmergebranch(repo, action=action, sourceset=sourceset,
                                onheadcheck=onheadcheck, destspace=destspace)
    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 = scmutil.revrange(repo, [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

def stackbase(ui, repo):
    # The histedit default base stops at public changesets, branchpoints,
    # and merges, which is exactly what we want for a stack.
    revs = scmutil.revrange(repo, [histeditdefaultrevset])
    return revs.last() if revs else None

def _statusotherbook(ui, repo):
    bmheads = bookmarks.headsforactive(repo)
    curhead = repo[repo._activebookmark].node()
    if repo.revs('%n and parents()', curhead):
        # we are on the active bookmark
        bmheads = [b for b in bmheads if curhead != b]
        if bmheads:
            msg = _('%i other divergent bookmarks for "%s"\n')
            ui.status(msg % (len(bmheads), repo._activebookmark))

def _statusotherbranchheads(ui, repo):
    currentbranch = repo.dirstate.branch()
    allheads = repo.branchheads(currentbranch, closed=True)
    heads = repo.branchheads(currentbranch)
    if repo.revs('%ln and parents()', allheads):
        # we are on a head, even though it might be closed
        #
        #  on closed otherheads
        #  ========= ==========
        #      o        0       all heads for current branch are closed
        #               N       only descendant branch heads are closed
        #      x        0       there is only one non-closed branch head
        #               N       there are some non-closed branch heads
        #  ========= ==========
        otherheads = repo.revs('%ln - parents()', heads)
        if repo['.'].closesbranch():
            ui.warn(_('no open descendant heads on branch "%s", '
                        'updating to a closed head\n') %
                      (currentbranch))
            if otherheads:
                ui.warn(_("(committing will reopen the head, "
                            "use 'hg heads .' to see %i other heads)\n") %
                          (len(otherheads)))
            else:
                ui.warn(_('(committing will reopen branch "%s")\n') %
                          (currentbranch))
        elif otherheads:
            curhead = repo['.']
            ui.status(_('updated to "%s: %s"\n') % (curhead,
                                    curhead.description().split('\n')[0]))
            ui.status(_('%i other heads for branch "%s"\n') %
                      (len(otherheads), currentbranch))

def statusotherdests(ui, repo):
    """Print message about other head"""
    # XXX we should probably include a hint:
    # - about what to do
    # - how to see such heads
    if repo._activebookmark:
        _statusotherbook(ui, repo)
    else:
        _statusotherbranchheads(ui, repo)