storageutil: move metadata parsing and packing from revlog (API)
Parsing and writing of revision text metadata is likely identical
across storage backends. Let's move the code out of revlog so we
don't need to import the revlog module in order to use it.
Differential Revision: https://phab.mercurial-scm.org/D4754
from __future__ import absolute_import, division, print_function
class FrozenInstanceError(AttributeError):
"""
A frozen/immutable instance has been attempted to be modified.
It mirrors the behavior of ``namedtuples`` by using the same error message
and subclassing :exc:`AttributeError`.
.. versionadded:: 16.1.0
"""
msg = "can't set attribute"
args = [msg]
class AttrsAttributeNotFoundError(ValueError):
"""
An ``attrs`` function couldn't find an attribute that the user asked for.
.. versionadded:: 16.2.0
"""
class NotAnAttrsClassError(ValueError):
"""
A non-``attrs`` class has been passed into an ``attrs`` function.
.. versionadded:: 16.2.0
"""
class DefaultAlreadySetError(RuntimeError):
"""
A default has been set using ``attr.ib()`` and is attempted to be reset
using the decorator.
.. versionadded:: 17.1.0
"""