Source code for pyxs.exceptions

# -*- coding: utf-8 -*-
"""
    pyxs.exceptions
    ~~~~~~~~~~~~~~~

    This module implements a number of Python exceptions used by
    :mod:`pyxs` classes.

    :copyright: (c) 2011 by Selectel, see AUTHORS for more details.
"""

__all__ = [
    "InvalidOperation", "InvalidPayload", "InvalidPath", "InvalidPermission",
    "ConnectionError", "UnexpectedPacket"
]


class PyXSError(Exception):
    """Base class for all :mod:`pyxs` exceptions."""


class InvalidOperation(ValueError, PyXSError):
    """Exception raised when :class:`~pyxs._internal.Packet` is passed
    an operation, which isn't listed in :data:`~pyxs._internal.Op`.

    :param int operation: invalid operation value.
    """


class InvalidPayload(ValueError, PyXSError):
    """Exception raised when :class:`~pyxs.Packet` is initialized with
    payload, which exceeds 4096 bytes restriction or contains a
    trailing ``NULL``.

    :param bytes operation: invalid payload value.
    """


class InvalidPath(ValueError, PyXSError):
    """Exception raised when a path proccessed by a comand doesn't
    match the following constraints:

    * its length should not exceed 3072 or 2048 for absolute and
      relative path respectively.
    * it should only consist of ASCII alphanumerics and the four
      punctuation characters ``-/_@`` -- `hyphen`, `slash`, `underscore`
      and `atsign`.
    * it shouldn't have a trailing ``/``, except for the root path.

    :param bytes path: invalid path value.
"""


class InvalidPermission(ValueError, PyXSError):
    """Exception raised for permission which don't match the following
    format::

        w<domid>	write only
        r<domid>	read only
        b<domid>	both read and write
        n<domid>	no access

    :param bytes perm: invalid permission value.
    """


class ConnectionError(PyXSError):
    """Exception raised for failures during socket operations."""


class UnexpectedPacket(ConnectionError):
    """Exception raised when recieved packet header doesn't match the
    header of the packet sent, for example if outgoing packet has
    ``op = Op.READ`` the incoming packet is expected to have
    ``op = Op.READ`` as well.
    """