~bzr-pqm/bzr/bzr.dev

# Copyright (C) 2005, 2006 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

"""XML externalization support."""

# "XML is like violence: if it doesn't solve your problem, you aren't

# using enough of it." -- various

# importing this module is fairly slow because it has to load several

# ElementTree bits

from bzrlib import registry

from bzrlib.trace import mutter, warning

try:

    try:

        # it's in this package in python2.5

        from xml.etree.cElementTree import (ElementTree, SubElement, Element,

            XMLTreeBuilder, fromstring, tostring)

        import xml.etree as elementtree

    except ImportError:

        from cElementTree import (ElementTree, SubElement, Element,

                                  XMLTreeBuilder, fromstring, tostring)

        import elementtree

    ParseError = SyntaxError

except ImportError:

    mutter('WARNING: using slower ElementTree; consider installing cElementTree'

           " and make sure it's on your PYTHONPATH")

    # this copy is shipped with bzr

    from util.elementtree.ElementTree import (ElementTree, SubElement,

                                              Element, XMLTreeBuilder,

                                              fromstring, tostring)

    import util.elementtree as elementtree

    from xml.parsers.expat import ExpatError as ParseError

from bzrlib import errors

class Serializer(object):

    """Abstract object serialize/deserialize"""

    def write_inventory(self, inv, f):

        """Write inventory to a file"""

        raise NotImplementedError(self.write_inventory)

    def write_inventory_to_string(self, inv):

        raise NotImplementedError(self.write_inventory_to_string)

    def read_inventory_from_string(self, xml_string, revision_id=None):

        """Read xml_string into an inventory object.

        :param xml_string: The xml to read.

        :param revision_id: If not-None, the expected revision id of the

            inventory. Some serialisers use this to set the results' root

            revision.

        """

        try:

            return self._unpack_inventory(fromstring(xml_string), revision_id)

        except ParseError, e:

            raise errors.UnexpectedInventoryFormat(e)

    def read_inventory(self, f, revision_id=None):

        try:

            return self._unpack_inventory(self._read_element(f),

                revision_id=None)

        except ParseError, e:

            raise errors.UnexpectedInventoryFormat(e)

    def write_revision(self, rev, f):

        self._write_element(self._pack_revision(rev), f)

    def write_revision_to_string(self, rev):

        return tostring(self._pack_revision(rev)) + '\n'

    def read_revision(self, f):

        return self._unpack_revision(self._read_element(f))

    def read_revision_from_string(self, xml_string):

        return self._unpack_revision(fromstring(xml_string))

    def _write_element(self, elt, f):

        ElementTree(elt).write(f, 'utf-8')

        f.write('\n')

    def _read_element(self, f):

        return ElementTree().parse(f)

# performance tuning for elementree's serialiser. This should be

# sent upstream - RBC 20060523.

# the functions here are patched into elementtree at runtime.

import re

escape_re = re.compile("[&'\"<>]")

escape_map = {

    "&":'&',

    "'":"'", # FIXME: overkill

    "\"":""",

    "<":"&lt;",

    ">":">",

    }

def _escape_replace(match, map=escape_map):

    return map[match.group()]

def _escape_attrib(text, encoding=None, replace=None):

    # escape attribute value

    try:

        if encoding:

            try:

                text = elementtree.ElementTree._encode(text, encoding)

            except UnicodeError:

                return elementtree.ElementTree._encode_entity(text)

        if replace is None:

            return escape_re.sub(_escape_replace, text)

        else:

            text = replace(text, "&", "&")

            text = replace(text, "'", "'") # FIXME: overkill

            text = replace(text, "\"", """)

            text = replace(text, "<", "&lt;")

            text = replace(text, ">", ">")

            return text

    except (TypeError, AttributeError):

        elementtree.ElementTree._raise_serialization_error(text)

elementtree.ElementTree._escape_attrib = _escape_attrib

escape_cdata_re = re.compile("[&<>]")

escape_cdata_map = {

    "&":'&',

    "<":"&lt;",

    ">":">",

    }

def _escape_cdata_replace(match, map=escape_cdata_map):

    return map[match.group()]

def _escape_cdata(text, encoding=None, replace=None):

    # escape character data

    try:

        if encoding:

            try:

                text = elementtree.ElementTree._encode(text, encoding)

            except UnicodeError:

                return elementtree.ElementTree._encode_entity(text)

        if replace is None:

            return escape_cdata_re.sub(_escape_cdata_replace, text)

        else:

            text = replace(text, "&", "&")

            text = replace(text, "<", "&lt;")

            text = replace(text, ">", ">")

            return text

    except (TypeError, AttributeError):

        elementtree.ElementTree._raise_serialization_error(text)

elementtree.ElementTree._escape_cdata = _escape_cdata

class SerializerRegistry(registry.Registry):

    """Registry for serializer objects"""

format_registry = SerializerRegistry()

format_registry.register_lazy('4', 'bzrlib.xml4', 'serializer_v4')

format_registry.register_lazy('5', 'bzrlib.xml5', 'serializer_v5')

format_registry.register_lazy('6', 'bzrlib.xml6', 'serializer_v6')

format_registry.register_lazy('7', 'bzrlib.xml7', 'serializer_v7')