view mercurial/txnutil.py @ 42530:dc3fdd1b5af4

state: created new class statecheck to handle unfinishedstates

For the purpose of handling states for various multistep operations like
`hg graft`, `hg histedit`, `hg bisect` et al a new class called statecheck
is created .This will help in having a unified approach towards these commands
and handle them with ease.

The class takes in 4 basic arguments which include the name of the command, the
name of the state file associated with it , clearable flag , allowcommit flag.

This also also adds the support of`checkunfinished()` and
`clearunfinished()` to the class.

Tests remain unchanged.

Differential Revision: https://phab.mercurial-scm.org/D6501

# 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)