# Source code for tables.exceptions

    # -*- coding: utf-8 -*-

    ########################################################################
    #
    # License: BSD
    # Created: December 17, 2004
    # Author:  Francesc Alted - faltet@pytables.com
    #
    # $Id$
    #
    ########################################################################

    """Declare exceptions and warnings that are specific to PyTables."""

    __docformat__ = 'reStructuredText'
    """The format of documentation strings in this module."""

    import os
    import warnings
    import traceback

    class HDF5ExtError(RuntimeError):
        """A low level HDF5 operation failed.

        This exception is raised the low level PyTables components used for
        accessing HDF5 files.  It usually signals that something is not
        going well in the HDF5 library or even at the Input/Output level.

        Errors in the HDF5 C library may be accompanied by an extensive
        HDF5 back trace on standard error (see also
        :func:`tables.silence_hdf5_messages`).

        .. versionchanged:: 2.4

        Parameters
        ----------
        message
            error message
        h5bt
            This parameter (keyword only) controls the HDF5 back trace
            handling. Any keyword arguments other than h5bt is ignored.

            * if set to False the HDF5 back trace is ignored and the
              :attr:`HDF5ExtError.h5backtrace` attribute is set to None
            * if set to True the back trace is retrieved from the HDF5
              library and stored in the :attr:`HDF5ExtError.h5backtrace`
              attribute as a list of tuples
            * if set to "VERBOSE" (default) the HDF5 back trace is
              stored in the :attr:`HDF5ExtError.h5backtrace` attribute
              and also included in the string representation of the
              exception
            * if not set (or set to None) the default policy is used
              (see :attr:`HDF5ExtError.DEFAULT_H5_BACKTRACE_POLICY`)

        """

        # NOTE: in order to avoid circular dependencies between modules the
        #       _dump_h5_backtrace method is set at initialization time in
        #       the utilsExtenion.
        _dump_h5_backtrace = None

        DEFAULT_H5_BACKTRACE_POLICY = "VERBOSE"
        """Default policy for HDF5 backtrace handling

        * if set to False the HDF5 back trace is ignored and the
          :attr:`HDF5ExtError.h5backtrace` attribute is set to None
        * if set to True the back trace is retrieved from the HDF5
          library and stored in the :attr:`HDF5ExtError.h5backtrace`
          attribute as a list of tuples
        * if set to "VERBOSE" (default) the HDF5 back trace is
          stored in the :attr:`HDF5ExtError.h5backtrace` attribute
          and also included in the string representation of the
          exception

        This parameter can be set using the
        :envvar:`PT_DEFAULT_H5_BACKTRACE_POLICY` environment variable.
        Allowed values are "IGNORE" (or "FALSE"), "SAVE" (or "TRUE") and
        "VERBOSE" to set the policy to False, True and "VERBOSE"
        respectively.  The special value "DEFAULT" can be used to reset
        the policy to the default value

        .. versionadded:: 2.4
        """

        @classmethod
        def set_policy_from_env(cls):
            envmap = {
                "IGNORE": False,
                "FALSE": False,
                "SAVE": True,
                "TRUE": True,
                "VERBOSE": "VERBOSE",
                "DEFAULT": "VERBOSE",
            }
            oldvalue = cls.DEFAULT_H5_BACKTRACE_POLICY
            envvalue = os.environ.get("PT_DEFAULT_H5_BACKTRACE_POLICY", "DEFAULT")
            try:
                newvalue = envmap[envvalue.upper()]
            except KeyError:
                warnings.warn("Invalid value for the environment variable "
                              "'PT_DEFAULT_H5_BACKTRACE_POLICY'.  The default "
                              "policy for HDF5 back trace management in PyTables "
                              "will be: '%s'" % oldvalue)
            else:
                cls.DEFAULT_H5_BACKTRACE_POLICY = newvalue

            return oldvalue

        def __init__(self, *args, **kargs):

            super(HDF5ExtError, self).__init__(*args)

            self._h5bt_policy = kargs.get('h5bt', self.DEFAULT_H5_BACKTRACE_POLICY)

            if self._h5bt_policy and self._dump_h5_backtrace is not None:
                self.h5backtrace = self._dump_h5_backtrace()
                """HDF5 back trace.

                Contains the HDF5 back trace as a (possibly empty) list of
                tuples.  Each tuple has the following format::

                    (filename, line number, function name, text)

                Depending on the value of the *h5bt* parameter passed to the
                initializer the h5backtrace attribute can be set to None.
                This means that the HDF5 back trace has been simply ignored
                (not retrieved from the HDF5 C library error stack) or that
                there has been an error (silently ignored) during the HDF5 back
                trace retrieval.

                .. versionadded:: 2.4

                See Also
                --------
                traceback.format_list : :func:`traceback.format_list`

                """

                # XXX: check _dump_h5_backtrace failures
            else:
                self.h5backtrace = None

        def __str__(self):
            """Returns a sting representation of the exception.

            The actual result depends on policy set in the initializer
            :meth:`HDF5ExtError.__init__`.

            .. versionadded:: 2.4

            """

            verbose = bool(self._h5bt_policy in ('VERBOSE', 'verbose'))

            if verbose and self.h5backtrace:
                bt = "\n".join([
                    "HDF5 error back trace\n",
                    self.format_h5_backtrace(),
                    "End of HDF5 error back trace"
                ])

                if len(self.args) == 1 and isinstance(self.args[0], basestring):
                    msg = super(HDF5ExtError, self).__str__()
                    msg = "%s\n\n%s" % (bt, msg)
                elif self.h5backtrace[-1][-1]:
                    msg = "%s\n\n%s" % (bt, self.h5backtrace[-1][-1])
                else:
                    msg = bt
            else:
                msg = super(HDF5ExtError, self).__str__()

            return msg

        def format_h5_backtrace(self, backtrace=None):
            """Convert the HDF5 trace back represented as a list of tuples.
            (see :attr:`HDF5ExtError.h5backtrace`) into a string.

            .. versionadded:: 2.4

            """
            if backtrace is None:
                backtrace = self.h5backtrace

            if backtrace is None:
                return 'No HDF5 back trace available'
            else:
                return ''.join(traceback.format_list(backtrace))

    # Initialize the policy for HDF5 back trace handling
    HDF5ExtError.set_policy_from_env()

    # The following exceptions are concretions of the ``ValueError`` exceptions
    # raised by ``file`` objects on certain operations.

    class ClosedNodeError(ValueError):
        """The operation can not be completed because the node is closed.

        For instance, listing the children of a closed group is not allowed.

        """

        pass

    class ClosedFileError(ValueError):
        """The operation can not be completed because the hosting file is closed.

        For instance, getting an existing node from a closed file is not
        allowed.

        """

        pass

    class FileModeError(ValueError):
        """The operation can not be carried out because the mode in which the
        hosting file is opened is not adequate.

        For instance, removing an existing leaf from a read-only file is not
        allowed.

        """

        pass

    class NodeError(AttributeError, LookupError):
        """Invalid hierarchy manipulation operation requested.

        This exception is raised when the user requests an operation on the
        hierarchy which can not be run because of the current layout of the
        tree.  This includes accessing nonexistent nodes, moving or copying
        or creating over an existing node, non-recursively removing groups
        with children, and other similarly invalid operations.

        A node in a PyTables database cannot be simply overwritten by
        replacing it.  Instead, the old node must be removed explicitely
        before another one can take its place.  This is done to protect
        interactive users from inadvertedly deleting whole trees of data by
        a single erroneous command.

        """

        pass

    class NoSuchNodeError(NodeError):
        """An operation was requested on a node that does not exist.

        This exception is raised when an operation gets a path name or a
        ``(where, name)`` pair leading to a nonexistent node.

        """

        pass

    class UndoRedoError(Exception):
        """Problems with doing/redoing actions with Undo/Redo feature.

        This exception indicates a problem related to the Undo/Redo
        mechanism, such as trying to undo or redo actions with this
        mechanism disabled, or going to a nonexistent mark.

        """

        pass

    class UndoRedoWarning(Warning):
        """Issued when an action not supporting Undo/Redo is run.

        This warning is only shown when the Undo/Redo mechanism is enabled.

        """

        pass

    class NaturalNameWarning(Warning):
        """Issued when a non-pythonic name is given for a node.

        This is not an error and may even be very useful in certain
        contexts, but one should be aware that such nodes cannot be
        accessed using natural naming (instead, ``getattr()`` must be
        used explicitly).
        """

        pass

    class PerformanceWarning(Warning):
        """Warning for operations which may cause a performance drop.

        This warning is issued when an operation is made on the database
        which may cause it to slow down on future operations (i.e. making
        the node tree grow too much).

        """

        pass

    class FlavorError(ValueError):
        """Unsupported or unavailable flavor or flavor conversion.

        This exception is raised when an unsupported or unavailable flavor
        is given to a dataset, or when a conversion of data between two
        given flavors is not supported nor available.

        """

        pass

    class FlavorWarning(Warning):
        """Unsupported or unavailable flavor conversion.

        This warning is issued when a conversion of data between two given
        flavors is not supported nor available, and raising an error would
        render the data inaccessible (e.g. on a dataset of an unavailable
        flavor in a read-only file).

        See the `FlavorError` class for more information.

        """

        pass

    class FiltersWarning(Warning):
        """Unavailable filters.

        This warning is issued when a valid filter is specified but it is
        not available in the system.  It may mean that an available default
        filter is to be used instead.

        """

        pass

    class OldIndexWarning(Warning):
        """Unsupported index format.

        This warning is issued when an index in an unsupported format is
        found.  The index will be marked as invalid and will behave as if
        doesn't exist.

        """

        pass

    class DataTypeWarning(Warning):
        """Unsupported data type.

        This warning is issued when an unsupported HDF5 data type is found
        (normally in a file created with other tool than PyTables).

        """

        pass

    class ExperimentalFeatureWarning(Warning):
        """Generic warning for experimental features.

        This warning is issued when using a functionality that is still
        experimental and that users have to use with care.

        """
        pass

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