mercurial/obsutil.py

namespaces: record and expose whether namespace is built-in

Currently, the templating layer tends to treat each namespace
as a one-off, with explicit usage of {bookmarks}, {tags}, {branch},
etc instead of using {namespaces}. It would be really useful if
we could iterate over namespaces and operate on them generically.
However, some consumers may wish to differentiate namespaces by
whether they are built-in to core Mercurial or provided by extensions.
Expected use cases include ignoring non-built-in namespaces or
emitting a generic label for non-built-in namespaces.

This commit introduces an attribute on namespace instances
that says whether the namespace is "built-in" and then exposes
this to the templating layer.

As part of this, we implement a reusable extension for defining
custom names on each changeset for testing. A second consumer
will be introduced in a subsequent commit.

# obsutil.py - utility functions for obsolescence
#
# Copyright 2017 Boris Feld <[e-mail]>
#
# 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

def closestpredecessors(repo, nodeid):
    """yield the list of next predecessors pointing on visible changectx nodes

    This function respect the repoview filtering, filtered revision will be
    considered missing.
    """

    precursors = repo.obsstore.precursors
    stack = [nodeid]
    seen = set(stack)

    while stack:
        current = stack.pop()
        currentpreccs = precursors.get(current, ())

        for prec in currentpreccs:
            precnodeid = prec[0]

            # Basic cycle protection
            if precnodeid in seen:
                continue
            seen.add(precnodeid)

            if precnodeid in repo:
                yield precnodeid
            else:
                stack.append(precnodeid)