# Source code for hdf5storage.lowlevel

    # Copyright (c) 2013-2016, Freja Nordsiek
    # All rights reserved.
    #
    # Redistribution and use in source and binary forms, with or without
    # modification, are permitted provided that the following conditions are
    # met:
    #
    # 1. Redistributions of source code must retain the above copyright
    # notice, this list of conditions and the following disclaimer.
    #
    # 2. Redistributions in binary form must reproduce the above copyright
    # notice, this list of conditions and the following disclaimer in the
    # documentation and/or other materials provided with the distribution.
    #
    # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
    # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
    # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
    # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
    # HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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    # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
    # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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    # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
    """ Module of Exceptions and low level read and write functions.

    """

    import posixpath

    import numpy as np
    import h5py

    from hdf5storage.utilities import *

    class Hdf5storageError(IOError):
        """ Base class of hdf5storage package exceptions."""
        pass

    class CantReadError(Hdf5storageError):
        """ Exception for a failure to read the desired data."""
        pass

    class TypeNotMatlabCompatibleError(Hdf5storageError):
        """ Exception for trying to write non-MATLAB compatible data.

        In the event that MATLAB compatibility is being done
        (``Options.matlab_compatible``) and a Python type is not importable
        by MATLAB, the data is either not written or this exception is
        thrown depending on the value of
        ``Options.action_for_matlab_incompatible``.

        See Also
        --------
        hdf5storage.Options.matlab_compatible
        hdf5storage.Options.action_for_matlab_incompatible

        """
        pass

    def write_data(f, grp, name, data, type_string, options):
        """ Writes a piece of data into an open HDF5 file.

        Low level function to store a Python type (`data`) into the
        specified Group.

        Parameters
        ----------
        f : h5py.File
            The open HDF5 file.
        grp : h5py.Group or h5py.File
            The Group to place the data in.
        name : str
            The name to write the data to.
        data : any
            The data to write.
        type_string : str or None
            The type string of the data, or ``None`` to deduce
            automatically.
        options : hdf5storage.core.Options
            The options to use when writing.

        Raises
        ------
        NotImplementedError
            If writing `data` is not supported.
        TypeNotMatlabCompatibleError
            If writing a type not compatible with MATLAB and
            `options.action_for_matlab_incompatible` is set to ``'error'``.

        See Also
        --------
        hdf5storage.core.write : Higher level version.
        read_data
        hdf5storage.core.Options

        """
        # Get the marshaller for type(data).

        tp = type(data)
        m = options.marshaller_collection.get_marshaller_for_type(tp)

        # If a marshaller was found, use it to write the data. Otherwise,
        # return an error. If we get something other than None back, then we
        # must recurse through the entries. Also, we must set the H5PATH
        # attribute to be the path to the containing group.

        if m is not None:
            m.write(f, grp, name, data, type_string, options)
        else:
            raise NotImplementedError('Can''t write data type: '+str(tp))

    def read_data(f, grp, name, options):
        """ Writes a piece of data into an open HDF5 file.

        Low level function to read a Python type of the specified name from
        specified Group.

        Parameters
        ----------
        f : h5py.File
            The open HDF5 file.
        grp : h5py.Group or h5py.File
            The Group to read the data from.
        name : str
            The name of the data to read.
        options : hdf5storage.core.Options
            The options to use when reading.

        Returns
        -------
        data
            The data named `name` in Group `grp`.

        Raises
        ------
        CantReadError
            If the data cannot be read successfully.

        See Also
        --------
        hdf5storage.core.read : Higher level version.
        write_data
        hdf5storage.core.Options

        """
        # If name isn't found, return error.
        if name not in grp:
            raise CantReadError('Could not find '
                                + posixpath.join(grp.name, name))

        # Get the different attributes that can be used to identify they
        # type, which are the type string and the MATLAB class.
        type_string = get_attribute_string(grp[name], 'Python.Type')
        matlab_class = get_attribute_string(grp[name], 'MATLAB_class')

        # If the type_string is present, get the marshaller for it. If it is
        # not, use the one for the matlab class if it is given. Otherwise,
        # use the fallback (NumpyScalarArrayMarshaller for both Datasets and
        # Groups). If calls to the marshaller collection to get the right
        # marshaller don't return one (return None), we also go to the
        # default).

        m = None
        mc = options.marshaller_collection
        if type_string is not None:
            m = mc.get_marshaller_for_type_string(type_string)
        elif matlab_class is not None:
            m = mc.get_marshaller_for_matlab_class(matlab_class)

        if m is None:
            m = mc.get_marshaller_for_type(np.uint8)

        # If a marshaller was found, use it to write the data. Otherwise,
        # return an error.

        if m is not None:
            return m.read(f, grp, name, options)
        else:
            raise CantReadError('Could not read ' + grp[name].name)