view mercurial/txnutil.py @ 47895:22c39f8acf78

dirstate-item: feed more information to `__init__`

Instead of processing the "rich" value at the `dirstatemap` level, we can now directly pass them to the DirstateItem object. This will make the object free to store whatever its want and to implements it logic whatever its want.

For now… we simply process the flag and store the same good old value. However
this pave the way for doing things differently once the rest of dirstatemap
code is updated.

Nobody call this code yet.

Differential Revision: https://phab.mercurial-scm.org/D11320

# 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(b'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(b'%s.pending' % filename, **kwargs), True)
        except IOError as inst:
            if inst.errno != errno.ENOENT:
                raise
    return (vfs(filename, **kwargs), False)