~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2008, 2009, 2010 Canonical Ltd

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

#

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

#

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

#

"""B+Tree index parsing."""

from bzrlib import static_tuple

def _parse_leaf_lines(bytes, key_length, ref_list_length):

    lines = bytes.split('\n')

    nodes = []

    as_st = static_tuple.StaticTuple.from_sequence

    stuple = static_tuple.StaticTuple

    for line in lines[1:]:

        if line == '':

            return nodes

        elements = line.split('\0', key_length)

        # keys are tuples

        key = as_st(elements[:key_length]).intern()

        line = elements[-1]

        references, value = line.rsplit('\0', 1)

        if ref_list_length:

            ref_lists = []

            for ref_string in references.split('\t'):

                ref_list = as_st([as_st(ref.split('\0')).intern()

                                  for ref in ref_string.split('\r') if ref])

                ref_lists.append(ref_list)

            ref_lists = as_st(ref_lists)

            node_value = stuple(value, ref_lists)

        else:

            node_value = stuple(value, stuple())

        # No need for StaticTuple here as it is put into a dict

        nodes.append((key, node_value))

    return nodes

def _flatten_node(node, reference_lists):

    """Convert a node into the serialized form.

    :param node: A tuple representing a node (key_tuple, value, references)

    :param reference_lists: Does this index have reference lists?

    :return: (string_key, flattened)

        string_key  The serialized key for referencing this node

        flattened   A string with the serialized form for the contents

    """

    if reference_lists:

        # TODO: Consider turning this back into the 'unoptimized' nested loop

        #       form. It is probably more obvious for most people, and this is

        #       just a reference implementation.

        flattened_references = ['\r'.join(['\x00'.join(reference)

                                           for reference in ref_list])

                                for ref_list in node[3]]

    else:

        flattened_references = []

    string_key = '\x00'.join(node[1])

    line = ("%s\x00%s\x00%s\n" % (string_key,

        '\t'.join(flattened_references), node[2]))

    return string_key, line