数据库发生错误。

# Copyright (C) 2001-2006 Python Software Foundation
# Author: Barry Warsaw
# Contact: email-sig@python.org

"""email package exception classes."""



class MessageError(Exception):
    """Base class for errors in the email package."""


class MessageParseError(MessageError):
    """Base class for message parsing errors."""


class HeaderParseError(MessageParseError):
    """Error while parsing headers."""


class BoundaryError(MessageParseError):
    """Couldn't find terminating boundary."""


class MultipartConversionError(MessageError, TypeError):
    """Conversion to a multipart is prohibited."""


class CharsetError(MessageError):
    """An illegal charset was given."""



# These are parsing defects which the parser was able to work around.
class MessageDefect:
    """Base class for a message defect."""

    def __init__(self, line=None):
        self.line = line

class NoBoundaryInMultipartDefect(MessageDefect):
    """A message claimed to be a multipart but had no boundary parameter."""

class StartBoundaryNotFoundDefect(MessageDefect):
    """The claimed start boundary was never found."""

class FirstHeaderLineIsContinuationDefect(MessageDefect):
    """A message had a continuation line as its first header line."""

class MisplacedEnvelopeHeaderDefect(MessageDefect):
    """A 'Unix-from' header was found in the middle of a header block."""

class MalformedHeaderDefect(MessageDefect):
    """Found a header that was missing a colon, or was otherwise malformed."""

class MultipartInvariantViolationDefect(MessageDefect):
    """A message claimed to be a multipart but no subparts were found."""