~bzr-pqm/bzr/bzr.dev

# (C) 2005 Canonical

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

import bzrlib.errors

from bzrlib.graph import farthest_node

class RevisionReference(object):

    """

    Reference to a stored revision.

    Includes the revision_id and revision_sha1.

    """

    revision_id = None

    revision_sha1 = None

    def __init__(self, revision_id, revision_sha1=None):

        if revision_id == None \

           or isinstance(revision_id, basestring):

            self.revision_id = revision_id

        else:

            raise ValueError('bad revision_id %r' % revision_id)

        if revision_sha1 != None:

            if isinstance(revision_sha1, basestring) \

               and len(revision_sha1) == 40:

                self.revision_sha1 = revision_sha1

            else:

                raise ValueError('bad revision_sha1 %r' % revision_sha1)

class Revision(object):

    """Single revision on a branch.

    Revisions may know their revision_hash, but only once they've been

    written out.  This is not stored because you cannot write the hash

    into the file it describes.

    After bzr 0.0.5 revisions are allowed to have multiple parents.

    parents

        List of parent revisions, each is a RevisionReference.

    """

    inventory_id = None

    inventory_sha1 = None

    revision_id = None

    timestamp = None

    message = None

    timezone = None

    committer = None

    def __init__(self, **args):

        self.__dict__.update(args)

        self.parents = []

    def __repr__(self):

        return "<Revision id %s>" % self.revision_id

    def to_element(self):

        from bzrlib.xml import Element, SubElement

        root = Element('revision',

                       committer = self.committer,

                       timestamp = '%.9f' % self.timestamp,

                       revision_id = self.revision_id,

                       inventory_id = self.inventory_id,

                       inventory_sha1 = self.inventory_sha1,

                       )

        if self.timezone:

            root.set('timezone', str(self.timezone))

        root.text = '\n'

        msg = SubElement(root, 'message')

        msg.text = self.message

        msg.tail = '\n'

        if self.parents:

            pelts = SubElement(root, 'parents')

            pelts.tail = pelts.text = '\n'

            for rr in self.parents:

                assert isinstance(rr, RevisionReference)

                p = SubElement(pelts, 'revision_ref')

                p.tail = '\n'

                assert rr.revision_id

                p.set('revision_id', rr.revision_id)

                if rr.revision_sha1:

                    p.set('revision_sha1', rr.revision_sha1)

        return root

    def from_element(cls, elt):

        return unpack_revision(elt)

    from_element = classmethod(from_element)

def unpack_revision(elt):

    """Convert XML element into Revision object."""

    # <changeset> is deprecated...

    if elt.tag not in ('revision', 'changeset'):

        raise bzrlib.errors.BzrError("unexpected tag in revision file: %r" % elt)

    rev = Revision(committer = elt.get('committer'),

                   timestamp = float(elt.get('timestamp')),

                   revision_id = elt.get('revision_id'),

                   inventory_id = elt.get('inventory_id'),

                   inventory_sha1 = elt.get('inventory_sha1')

                   )

    precursor = elt.get('precursor')

    precursor_sha1 = elt.get('precursor_sha1')

    pelts = elt.find('parents')

    if pelts:

        for p in pelts:

            assert p.tag == 'revision_ref', \

                   "bad parent node tag %r" % p.tag

            rev_ref = RevisionReference(p.get('revision_id'),

                                        p.get('revision_sha1'))

            rev.parents.append(rev_ref)

        if precursor:

            # must be consistent

            prec_parent = rev.parents[0].revision_id

            assert prec_parent == precursor

    elif precursor:

        # revisions written prior to 0.0.5 have a single precursor

        # give as an attribute

        rev_ref = RevisionReference(precursor, precursor_sha1)

        rev.parents.append(rev_ref)

    v = elt.get('timezone')

    rev.timezone = v and int(v)

    rev.message = elt.findtext('message') # text of <message>

    return rev

REVISION_ID_RE = None

def validate_revision_id(rid):

    """Check rid is syntactically valid for a revision id."""

    global REVISION_ID_RE

    if not REVISION_ID_RE:

        import re

        REVISION_ID_RE = re.compile('[\w.-]+@[\w.-]+--?\d+--?[0-9a-f]+\Z')

    if not REVISION_ID_RE.match(rid):

        raise ValueError("malformed revision-id %r" % rid)

def is_ancestor(revision_id, candidate_id, revision_source):

    """Return true if candidate_id is an ancestor of revision_id.

    A false negative will be returned if any intermediate descendent of

    candidate_id is not present in any of the revision_sources.

    revisions_source is an object supporting a get_revision operation that

    behaves like Branch's.

    """

    for ancestor_id, distance in iter_ancestors(revision_id, revision_source):

        if ancestor_id == candidate_id:

            return True

    return False

def iter_ancestors(revision_id, revision_source, only_present=False):

    ancestors = (revision_id,)

    distance = 0

    while len(ancestors) > 0:

        new_ancestors = []

        for ancestor in ancestors:

            if not only_present:

                yield ancestor, distance

            try:

                revision = revision_source.get_revision(ancestor)

            except bzrlib.errors.NoSuchRevision, e:

                if e.revision == revision_id:

                    raise 

                else:

                    continue

            if only_present:

                yield ancestor, distance

            new_ancestors.extend([p.revision_id for p in revision.parents])

        ancestors = new_ancestors

        distance += 1

def find_present_ancestors(revision_id, revision_source):

    """Return the ancestors of a revision present in a branch.

    It's possible that a branch won't have the complete ancestry of

    one of its revisions.  

    """

    found_ancestors = {}

    anc_iter = enumerate(iter_ancestors(revision_id, revision_source,

                         only_present=True))

    for anc_order, (anc_id, anc_distance) in anc_iter:

        if not found_ancestors.has_key(anc_id):

            found_ancestors[anc_id] = (anc_order, anc_distance)

    return found_ancestors

def __get_closest(intersection):

    intersection.sort()

    matches = [] 

    for entry in intersection:

        if entry[0] == intersection[0][0]:

            matches.append(entry[2])

    return matches

def common_ancestor(revision_a, revision_b, revision_source):

    """Find the ancestor common to both revisions that is closest to both.

    """

    from bzrlib.trace import mutter

    a_ancestors = find_present_ancestors(revision_a, revision_source)

    b_ancestors = find_present_ancestors(revision_b, revision_source)

    a_intersection = []

    b_intersection = []

    # a_order is used as a tie-breaker when two equally-good bases are found

    for revision, (a_order, a_distance) in a_ancestors.iteritems():

        if b_ancestors.has_key(revision):

            a_intersection.append((a_distance, a_order, revision))

            b_intersection.append((b_ancestors[revision][1], a_order, revision))

    mutter("a intersection: %r" % a_intersection)

    mutter("b intersection: %r" % b_intersection)

    a_closest = __get_closest(a_intersection)

    if len(a_closest) == 0:

        return None

    b_closest = __get_closest(b_intersection)

    assert len(b_closest) != 0

    mutter ("a_closest %r" % a_closest)

    mutter ("b_closest %r" % b_closest)

    if a_closest[0] in b_closest:

        return a_closest[0]

    elif b_closest[0] in a_closest:

        return b_closest[0]

    else:

        raise bzrlib.errors.AmbiguousBase((a_closest[0], b_closest[0]))

    return a_closest[0]

def revision_graph(revision, revision_source):

    ancestors = {}

    descendants = {}

    lines = [revision]

    root = None

    descendants[revision] = {}

    while len(lines) > 0:

        new_lines = set()

        for line in lines:

            try:

                rev = revision_source.get_revision(line)

                parents = [p.revision_id for p in rev.parents]

                if len(parents) == 0:

                    root = line

            except bzrlib.errors.NoSuchRevision:

                parents = None

            if parents is not None:

                for parent in parents:

                    if parent not in ancestors:

                        new_lines.add(parent)

                    if parent not in descendants:

                        descendants[parent] = {}

                    descendants[parent][line] = 1

            if parents is not None:

                ancestors[line] = set(parents)

        lines = new_lines

    assert root not in descendants[root]

    assert root not in ancestors[root]

    return root, ancestors, descendants

def combined_graph(revision_a, revision_b, revision_source):

    root, ancestors, descendants = revision_graph(revision_a, revision_source)

    root_b, ancestors_b, descendants_b = revision_graph(revision_b, 

                                                        revision_source)

    assert root == root_b

    common = set()

    for node, node_anc in ancestors_b.iteritems():

        if node in ancestors:

            common.add(node)

        else:

            ancestors[node] = set()

        ancestors[node].update(node_anc)

    for node, node_dec in descendants_b.iteritems():

        if node not in descendants:

            descendants[node] = set()

        descendants[node].update(node_dec)

    return root, ancestors, descendants, common

def common_ancestor(revision_a, revision_b, revision_source):

    root, ancestors, descendants, common = \

        combined_graph(revision_a, revision_b, revision_source)

    nodes = farthest_node(descendants, ancestors, root)

    for node in nodes:

        if node in common:

            return node

class MultipleRevisionSources(object):

    """Proxy that looks in multiple branches for revisions."""

    def __init__(self, *args):

        object.__init__(self)

        assert len(args) != 0

        self._revision_sources = args

    def get_revision(self, revision_id):

        for source in self._revision_sources:

            try:

                return source.get_revision(revision_id)

            except bzrlib.errors.NoSuchRevision, e:

                pass

        raise e

def get_intervening_revisions(ancestor_id, rev_id, rev_source, 

                              revision_history=None):

    """Find the longest line of descent from maybe_ancestor to revision.

    Revision history is followed where possible.

    If ancestor_id == rev_id, list will be empty.

    Otherwise, rev_id will be the last entry.  ancestor_id will never appear.

    If ancestor_id is not an ancestor, NotAncestor will be thrown

    """

    [rev_source.get_revision(r) for r in (ancestor_id, rev_id)]

    if ancestor_id == rev_id:

        return []

    def historical_lines(line):

        """Return a tuple of historical/non_historical lines, for sorting.

        The non_historical count is negative, since non_historical lines are

        a bad thing.

        """

        good_count = 0

        bad_count = 0

        for revision in line:

            if revision in revision_history:

                good_count += 1

            else:

                bad_count -= 1

        return good_count, bad_count

    active = [[rev_id]]

    successful_lines = []

    while len(active) > 0:

        new_active = []

        for line in active:

            parent_ids = [p.revision_id for p in 

                          rev_source.get_revision(line[-1]).parents]

            for parent in parent_ids:

                line_copy = line[:]

                if parent == ancestor_id:

                    successful_lines.append(line_copy)

                else:

                    line_copy.append(parent)

                    new_active.append(line_copy)

        active = new_active

    if len(successful_lines) == 0:

        raise bzrlib.errors.NotAncestor(rev_id, ancestor_id)

    for line in successful_lines:

        line.reverse()

    if revision_history is not None:

        by_historical_lines = []

        for line in successful_lines:

            count = historical_lines(line)

            by_historical_lines.append((count, line))

        by_historical_lines.sort()

        if by_historical_lines[-1][0][0] > 0:

            return by_historical_lines[-1][1]

    assert len(successful_lines)

    successful_lines.sort(cmp, len)

    return successful_lines[-1]