hgext/narrow/narrowtemplates.py

revlog: extract function for getting node from known-to-exist rev

Many of the calls to index_node() (which converts a rev to a nodeid)
are done with a rev that's know to exist. If the function fails,
there's something really wrong and we should just abort. This was done
in only one place. This patch starts by extracting that code to a
function that we can reuse in later patches.

Differential Revision: https://phab.mercurial-scm.org/D3456

# narrowtemplates.py - added template keywords for narrow clones
#
# Copyright 2017 Google, Inc.
#
# 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 mercurial import (
    registrar,
    revlog,
)

keywords = {}
templatekeyword = registrar.templatekeyword(keywords)
revsetpredicate = registrar.revsetpredicate()

def _isellipsis(repo, rev):
    if repo.changelog.flags(rev) & revlog.REVIDX_ELLIPSIS:
        return True
    return False

@templatekeyword('ellipsis', requires={'repo', 'ctx'})
def ellipsis(context, mapping):
    """String. 'ellipsis' if the change is an ellipsis node, else ''."""
    repo = context.resource(mapping, 'repo')
    ctx = context.resource(mapping, 'ctx')
    if _isellipsis(repo, ctx.rev()):
        return 'ellipsis'
    return ''

@templatekeyword('outsidenarrow', requires={'repo', 'ctx'})
def outsidenarrow(context, mapping):
    """String. 'outsidenarrow' if the change affects no tracked files,
    else ''."""
    repo = context.resource(mapping, 'repo')
    ctx = context.resource(mapping, 'ctx')
    m = repo.narrowmatch()
    if not m.always():
        if not any(m(f) for f in ctx.files()):
            return 'outsidenarrow'
    return ''

@revsetpredicate('ellipsis')
def ellipsisrevset(repo, subset, x):
    """Changesets that are ellipsis nodes."""
    return subset.filter(lambda r: _isellipsis(repo, r))