/b-gtk/fix-viz

#!/usr/bin/python

# -*- coding: UTF-8 -*-

"""Directed graph production.

This module contains the code to produce an ordered directed graph of a

bzr branch, such as we display in the tree view at the top of the bzrk

window.

"""

__copyright__ = "Copyright © 2005 Canonical Ltd."

__author__    = "Scott James Remnant <scott@ubuntu.com>"

from bzrlib.errors import NoSuchRevision

class DummyRevision(object):

    """Dummy bzr revision.

    Sometimes, especially in older bzr branches, a revision is referenced

    as the parent of another but not actually present in the branch's store.

    When this happens we use an instance of this class instead of the real

    Revision object (which we can't get).

    """

    def __init__(self, revid):

        self.revision_id = revid

        self.parent_ids = []

        self.committer = None

        self.message = self.revision_id

def distances(branch, start):

    """Sort the revisions.

    Traverses the branch revision tree starting at start and produces an

    ordered list of revisions such that a revision always comes after

    any revision it is the parent of.

    Returns a tuple of (revids, revisions, colours, children)

    """

    revisions = { start: branch.get_revision(start) }

    children = { revisions[start]: set() }

    distances = { start: 0 }

    colours = { start: 0 }

    last_colour = 0

    # Sort the revisions; the fastest way to do this is to visit each node

    # as few times as possible (by keeping the todo list in a set) and record

    # the largest distance to it before queuing up the children if we

    # increased the distance.  This produces the sort order we desire

    todo = set([ start ])

    while todo:

        revid = todo.pop()

        revision = revisions[revid]

        distance = distances[revid] + 1

        colour = colours[revid]

        for parent_id in revision.parent_ids:

            # Check whether there's any point re-processing this

            if parent_id in distances and distances[parent_id] >= distance:

                continue

            # Get the parent from the cache, or put it in the cache

            try:

                parent = revisions[parent_id]

                children[parent].add(revision)

            except KeyError:

                try:

                    parent = revisions[parent_id] \

                             = branch.get_revision(parent_id)

                except NoSuchRevision:

                    parent = revisions[parent_id] = DummyRevision(parent_id)

                children[parent] = set([ revision ])

            # Penalise revisions a little at a fork if we think they're on

            # the same branch -- this makes the few few (at least) revisions

            # of a branch appear straight after the fork

            if same_branch(revision, parent):

                colours[parent_id] = colour

                if len(revision.parent_ids) > 1:

                    distances[parent_id] = distance + 10

                else:

                    distances[parent_id] = distance

            else:

                colours[parent_id] = last_colour = last_colour + 1

                distances[parent_id] = distance

            todo.add(parent_id)

    return ( sorted(distances, key=distances.get), revisions, colours,

             children )

def graph(revids, revisions, colours):

    """Produce a directed graph of a bzr branch.

    For each revision it then yields a tuple of (revision, node, lines).

    If the revision is only referenced in the branch and not present in the

    store, revision will be a DummyRevision object, otherwise it is the bzr

    Revision object with the meta-data for the revision.

    Node is a tuple of (column, colour) with column being a zero-indexed

    column number of the graph that this revision represents and colour

    being a zero-indexed colour (which doesn't specify any actual colour

    in particular) to draw the node in.

    Lines is a list of tuples which represent lines you should draw away

    from the revision, if you also need to draw lines into the revision

    you should use the lines list from the previous iteration.  Each

    typle in the list is in the form (start, end, colour) with start and

    end being zero-indexed column numbers and colour as in node.

    It's up to you how to actually draw the nodes and lines (straight,

    curved, kinked, etc.) and to pick the actual colours for each index.

    """

    hanging = revids[:1]

    for revid in revids:

        lines = []

        node = None

        new_hanging = []

        for h_idx, hang in enumerate(hanging):

            if hang == revid:

                # We've matched a hanging revision, so need to output a node

                # at this point

                node = (h_idx, colours[revid])

                # Now we need to hang its parents, we put them at the point

                # the old column was so anything to the right of this has

                # to move outwards to make room.  We also try and collapse

                # hangs to keep the graph small.

                for parent_id in revisions[revid].parent_ids:

                    try:

                        n_idx = new_hanging.index(parent_id)

                    except ValueError:

                        n_idx = len(new_hanging)

                        new_hanging.append(parent_id)

                    lines.append((h_idx, n_idx, colours[parent_id]))

            else:

                # Revision keeps on hanging, adjust for any change in the

                # graph shape and try to collapse hangs to keep the graph

                # small.

                try:

                    n_idx = new_hanging.index(hang)

                except ValueError:

                    n_idx = len(new_hanging)

                    new_hanging.append(hang)

                lines.append((h_idx, n_idx, colours[hang]))

        hanging = new_hanging

        yield (revisions[revid], node, lines)

def same_branch(a, b):

    """Return whether we think revisions a and b are on the same branch."""

    if len(a.parent_ids) == 1:

        # Defacto same branch if only parent

        return True

    elif a.committer == b.committer:

        # Same committer so may as well be

        return True

    else:

        return False