mercurial/txnutil.py

formatter: put topic in templatespec tuple

This will allow us to change the initial template reference depending on how
the template is looked up. For example,

  -Tdefault => (ref='changeset', tmpl=None, mapfile='map-cmdline.default')
  -T'{rev}' => (ref='', tmpl='{rev}', mapfile=None)

A literal template given by -T option will be stored as an unnamed template,
which will free up the template namespace so that we can load named templates
from [templates] section of user config.

# txnutil.py - transaction related utilities
#
#  Copyright FUJIWARA Katsunori <[e-mail]> and others
#
# 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

import errno

from . import (
    encoding,
)

def mayhavepending(root):
    '''return whether 'root' may have pending changes, which are
    visible to this process.
    '''
    return root == encoding.environ.get('HG_PENDING')

def trypending(root, vfs, filename, **kwargs):
    '''Open  file to be read according to HG_PENDING environment variable

    This opens '.pending' of specified 'filename' only when HG_PENDING
    is equal to 'root'.

    This returns '(fp, is_pending_opened)' tuple.
    '''
    if mayhavepending(root):
        try:
            return (vfs('%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)