view mercurial/txnutil.py @ 51626:865efc020c33 default tip

dirstate: remove the python-side whitelist of allowed matchers

This whitelist is too permissive because it allows matchers that contain
disallowed ones deep inside, for example through `intersectionmatcher`.

It is also too restrictive because it doesn't pass through
some of the matchers we support, such as `patternmatcher`.

It's also unnecessary because unsupported matchers raise
`FallbackError` and we fall back anyway.

Making this change makes more of the tests use rust code path,
and therefore subtly change behavior. For example, rust status
in largefiles repos seems to have strange behavior.

# 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 . 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 FileNotFoundError:
            pass
    return (vfs(filename, **kwargs), False)