root/calcium/trunk/lib/feedparser.py

#!/usr/bin/env python
"""Universal feed parser

Handles RSS 0.9x, RSS 1.0, RSS 2.0, CDF, Atom 0.3, and Atom 1.0 feeds

Visit http://feedparser.org/ for the latest version
Visit http://feedparser.org/docs/ for the latest documentation

Required: Python 2.1 or later
Recommended: Python 2.3 or later
Recommended: CJKCodecs and iconv_codec <http://cjkpython.i18n.org/>
"""

__version__ = "4.2-pre-" + "$Revision: 1.95 $"[11:15] + "-cvs"
__license__ = """Copyright (c) 2002-2006, Mark Pilgrim, All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice,
  this list of conditions and the following disclaimer.
* 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 OWNER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE."""
__author__ = "Mark Pilgrim <http://diveintomark.org/>"
__contributors__ = ["Jason Diamond <http://injektilo.org/>",
                    "John Beimler <http://john.beimler.org/>",
                    "Fazal Majid <http://www.majid.info/mylos/weblog/>",
                    "Aaron Swartz <http://aaronsw.com/>",
                    "Kevin Marks <http://epeus.blogspot.com/>"]
_debug = 0

# HTTP "User-Agent" header to send to servers when downloading feeds.
# If you are embedding feedparser in a larger application, you should
# change this to your application name and URL.
USER_AGENT = "UniversalFeedParser/%s +http://feedparser.org/" % __version__

# HTTP "Accept" header to send to servers when downloading feeds.  If you don't
# want to send an Accept header, set this to None.
ACCEPT_HEADER = "application/atom+xml,application/rdf+xml,application/rss+xml,application/x-netcdf,application/xml;q=0.9,text/xml;q=0.2,*/*;q=0.1"

# List of preferred XML parsers, by SAX driver name.  These will be tried first,
# but if they're not installed, Python will keep searching through its own list
# of pre-installed parsers until it finds one that supports everything we need.
PREFERRED_XML_PARSERS = ["drv_libxml2"]

# If you want feedparser to automatically run HTML markup through HTML Tidy, set
# this to 1.  Requires mxTidy <http://www.egenix.com/files/python/mxTidy.html>
# or utidylib <http://utidylib.berlios.de/>.
TIDY_MARKUP = 0

# List of Python interfaces for HTML Tidy, in order of preference.  Only useful
# if TIDY_MARKUP = 1
PREFERRED_TIDY_INTERFACES = ["uTidy", "mxTidy"]

# ---------- required modules (should come with any Python distribution) ----------
import sgmllib, re, sys, copy, urlparse, time, rfc822, types, cgi, urllib, urllib2
try:
    from cStringIO import StringIO as _StringIO
except:
    from StringIO import StringIO as _StringIO

# ---------- optional modules (feedparser will work without these, but with reduced functionality) ----------

# gzip is included with most Python distributions, but may not be available if you compiled your own
try:
    import gzip
except:
    gzip = None
try:
    import zlib
except:
    zlib = None

# If a real XML parser is available, feedparser will attempt to use it.  feedparser has
# been tested with the built-in SAX parser, PyXML, and libxml2.  On platforms where the
# Python distribution does not come with an XML parser (such as Mac OS X 10.2 and some
# versions of FreeBSD), feedparser will quietly fall back on regex-based parsing.
try:
    import xml.sax
    xml.sax.make_parser(PREFERRED_XML_PARSERS) # test for valid parsers
    from xml.sax.saxutils import escape as _xmlescape
    _XML_AVAILABLE = 1
except:
    _XML_AVAILABLE = 0
    def _xmlescape(data):
        data = data.replace('&', '&amp;')
        data = data.replace('>', '&gt;')
        data = data.replace('<', '&lt;')
        return data

# base64 support for Atom feeds that contain embedded binary data
try:
    import base64, binascii
except:
    base64 = binascii = None

# cjkcodecs and iconv_codec provide support for more character encodings.
# Both are available from http://cjkpython.i18n.org/
try:
    import cjkcodecs.aliases
except:
    pass
try:
    import iconv_codec
except:
    pass

# chardet library auto-detects character encodings
# Download from http://chardet.feedparser.org/
try:
    import chardet
    if _debug:
        import chardet.constants
        chardet.constants._debug = 1
except:
    chardet = None

# BeautifulSoup parser used for parsing microformats from embedded HTML content
# http://www.crummy.com/software/BeautifulSoup/
try:
    import BeautifulSoup
except:
    BeautifulSoup = None

# ---------- don't touch these ----------
class ThingsNobodyCaresAboutButMe(Exception): pass
class CharacterEncodingOverride(ThingsNobodyCaresAboutButMe): pass
class CharacterEncodingUnknown(ThingsNobodyCaresAboutButMe): pass
class NonXMLContentType(ThingsNobodyCaresAboutButMe): pass
class UndeclaredNamespace(Exception): pass

sgmllib.tagfind = re.compile('[a-zA-Z][-_.:a-zA-Z0-9]*')
sgmllib.special = re.compile('<!')
sgmllib.charref = re.compile('&#(x?[0-9A-Fa-f]+)[^0-9A-Fa-f]')

SUPPORTED_VERSIONS = {'': 'unknown',
                      'rss090': 'RSS 0.90',
                      'rss091n': 'RSS 0.91 (Netscape)',
                      'rss091u': 'RSS 0.91 (Userland)',
                      'rss092': 'RSS 0.92',
                      'rss093': 'RSS 0.93',
                      'rss094': 'RSS 0.94',
                      'rss20': 'RSS 2.0',
                      'rss10': 'RSS 1.0',
                      'rss': 'RSS (unknown version)',
                      'atom01': 'Atom 0.1',
                      'atom02': 'Atom 0.2',
                      'atom03': 'Atom 0.3',
                      'atom10': 'Atom 1.0',
                      'atom': 'Atom (unknown version)',
                      'cdf': 'CDF',
                      'hotrss': 'Hot RSS'
                      }

try:
    UserDict = dict
except NameError:
    # Python 2.1 does not have dict
    from UserDict import UserDict
    def dict(aList):
        rc = {}
        for k, v in aList:
            rc[k] = v
        return rc

class FeedParserDict(UserDict):
    keymap = {'channel': 'feed',
              'items': 'entries',
              'guid': 'id',
              'date': 'updated',
              'date_parsed': 'updated_parsed',
              'description': ['subtitle', 'summary'],
              'url': ['href'],
              'modified': 'updated',
              'modified_parsed': 'updated_parsed',
              'issued': 'published',
              'issued_parsed': 'published_parsed',
              'copyright': 'rights',
              'copyright_detail': 'rights_detail',
              'tagline': 'subtitle',
              'tagline_detail': 'subtitle_detail'}
    def __getitem__(self, key):
        if key == 'category':
            return UserDict.__getitem__(self, 'tags')[0]['term']
        if key == 'categories':
            return [(tag['scheme'], tag['term']) for tag in UserDict.__getitem__(self, 'tags')]
        realkey = self.keymap.get(key, key)
        if type(realkey) == types.ListType:
            for k in realkey:
                if UserDict.has_key(self, k):
                    return UserDict.__getitem__(self, k)
        if UserDict.has_key(self, key):
            return UserDict.__getitem__(self, key)
        return UserDict.__getitem__(self, realkey)

    def __setitem__(self, key, value):
        for k in self.keymap.keys():
            if key == k:
                key = self.keymap[k]
                if type(key) == types.ListType:
                    key = key[0]
        return UserDict.__setitem__(self, key, value)

    def get(self, key, default=None):
        if self.has_key(key):
            return self[key]
        else:
            return default

    def setdefault(self, key, value):
        if not self.has_key(key):
            self[key] = value
        return self[key]
        
    def has_key(self, key):
        try:
            return hasattr(self, key) or UserDict.has_key(self, key)
        except AttributeError:
            return False
        
    def __getattr__(self, key):
        try:
            return self.__dict__[key]
        except KeyError:
            pass
        try:
            assert not key.startswith('_')
            return self.__getitem__(key)
        except:
            raise AttributeError, "object has no attribute '%s'" % key

    def __setattr__(self, key, value):
        if key.startswith('_') or key == 'data':
            self.__dict__[key] = value
        else:
            return self.__setitem__(key, value)

    def __contains__(self, key):
        return self.has_key(key)

def zopeCompatibilityHack():
    global FeedParserDict
    del FeedParserDict
    def FeedParserDict(aDict=None):
        rc = {}
        if aDict:
            rc.update(aDict)
        return rc

_ebcdic_to_ascii_map = None
def _ebcdic_to_ascii(s):
    global _ebcdic_to_ascii_map
    if not _ebcdic_to_ascii_map:
        emap = (
            0,1,2,3,156,9,134,127,151,141,142,11,12,13,14,15,
            16,17,18,19,157,133,8,135,24,25,146,143,28,29,30,31,
            128,129,130,131,132,10,23,27,136,137,138,139,140,5,6,7,
            144,145,22,147,148,149,150,4,152,153,154,155,20,21,158,26,
            32,160,161,162,163,164,165,166,167,168,91,46,60,40,43,33,
            38,169,170,171,172,173,174,175,176,177,93,36,42,41,59,94,
            45,47,178,179,180,181,182,183,184,185,124,44,37,95,62,63,
            186,187,188,189,190,191,192,193,194,96,58,35,64,39,61,34,
            195,97,98,99,100,101,102,103,104,105,196,197,198,199,200,201,
            202,106,107,108,109,110,111,112,113,114,203,204,205,206,207,208,
            209,126,115,116,117,118,119,120,121,122,210,211,212,213,214,215,
            216,217,218,219,220,221,222,223,224,225,226,227,228,229,230,231,
            123,65,66,67,68,69,70,71,72,73,232,233,234,235,236,237,
            125,74,75,76,77,78,79,80,81,82,238,239,240,241,242,243,
            92,159,83,84,85,86,87,88,89,90,244,245,246,247,248,249,
            48,49,50,51,52,53,54,55,56,57,250,251,252,253,254,255
            )
        import string
        _ebcdic_to_ascii_map = string.maketrans( \
            ''.join(map(chr, range(256))), ''.join(map(chr, emap)))
    return s.translate(_ebcdic_to_ascii_map)

_urifixer = re.compile('^([A-Za-z][A-Za-z0-9+-.]*://)(/*)(.*?)')
def _urljoin(base, uri):
    uri = _urifixer.sub(r'\1\3', uri)
    return urlparse.urljoin(base, uri)

class _FeedParserMixin:
    namespaces = {'': '',
                  'http://backend.userland.com/rss': '',
                  'http://blogs.law.harvard.edu/tech/rss': '',
                  'http://purl.org/rss/1.0/': '',
                  'http://my.netscape.com/rdf/simple/0.9/': '',
                  'http://example.com/newformat#': '',
                  'http://example.com/necho': '',
                  'http://purl.org/echo/': '',
                  'uri/of/echo/namespace#': '',
                  'http://purl.org/pie/': '',
                  'http://purl.org/atom/ns#': '',
                  'http://www.w3.org/2005/Atom': '',
                  'http://purl.org/rss/1.0/modules/rss091#': '',
                  
                  'http://webns.net/mvcb/':                               'admin',
                  'http://purl.org/rss/1.0/modules/aggregation/':         'ag',
                  'http://purl.org/rss/1.0/modules/annotate/':            'annotate',
                  'http://media.tangent.org/rss/1.0/':                    'audio',
                  'http://backend.userland.com/blogChannelModule':        'blogChannel',
                  'http://web.resource.org/cc/':                          'cc',
                  'http://backend.userland.com/creativeCommonsRssModule': 'creativeCommons',
                  'http://purl.org/rss/1.0/modules/company':              'co',
                  'http://purl.org/rss/1.0/modules/content/':             'content',
                  'http://my.theinfo.org/changed/1.0/rss/':               'cp',
                  'http://purl.org/dc/elements/1.1/':                     'dc',
                  'http://purl.org/dc/terms/':                            'dcterms',
                  'http://purl.org/rss/1.0/modules/email/':               'email',
                  'http://purl.org/rss/1.0/modules/event/':               'ev',
                  'http://rssnamespace.org/feedburner/ext/1.0':           'feedburner',
                  'http://freshmeat.net/rss/fm/':                         'fm',
                  'http://xmlns.com/foaf/0.1/':                           'foaf',
                  'http://www.w3.org/2003/01/geo/wgs84_pos#':             'geo',
                  'http://postneo.com/icbm/':                             'icbm',
                  'http://purl.org/rss/1.0/modules/image/':               'image',
                  'http://www.itunes.com/DTDs/PodCast-1.0.dtd':           'itunes',
                  'http://example.com/DTDs/PodCast-1.0.dtd':              'itunes',
                  'http://purl.org/rss/1.0/modules/link/':                'l',
                  'http://search.yahoo.com/mrss':                         'media',
                  'http://madskills.com/public/xml/rss/module/pingback/': 'pingback',
                  'http://prismstandard.org/namespaces/1.2/basic/':       'prism',
                  'http://www.w3.org/1999/02/22-rdf-syntax-ns#':          'rdf',
                  'http://www.w3.org/2000/01/rdf-schema#':                'rdfs',
                  'http://purl.org/rss/1.0/modules/reference/':           'ref',
                  'http://purl.org/rss/1.0/modules/richequiv/':           'reqv',
                  'http://purl.org/rss/1.0/modules/search/':              'search',
                  'http://purl.org/rss/1.0/modules/slash/':               'slash',
                  'http://schemas.xmlsoap.org/soap/envelope/':            'soap',
                  'http://purl.org/rss/1.0/modules/servicestatus/':       'ss',
                  'http://hacks.benhammersley.com/rss/streaming/':        'str',
                  'http://purl.org/rss/1.0/modules/subscription/':        'sub',
                  'http://purl.org/rss/1.0/modules/syndication/':         'sy',
                  'http://purl.org/rss/1.0/modules/taxonomy/':            'taxo',
                  'http://purl.org/rss/1.0/modules/threading/':           'thr',
                  'http://purl.org/rss/1.0/modules/textinput/':           'ti',
                  'http://madskills.com/public/xml/rss/module/trackback/':'trackback',
                  'http://wellformedweb.org/commentAPI/':                 'wfw',
                  'http://purl.org/rss/1.0/modules/wiki/':                'wiki',
                  'http://www.w3.org/1999/xhtml':                         'xhtml',
                  'http://www.w3.org/XML/1998/namespace':                 'xml',
                  'http://schemas.pocketsoap.com/rss/myDescModule/':      'szf'
}
    _matchnamespaces = {}

    can_be_relative_uri = ['link', 'id', 'wfw_comment', 'wfw_commentrss', 'docs', 'url', 'href', 'comments', 'license', 'icon', 'logo']
    can_contain_relative_uris = ['content', 'title', 'summary', 'info', 'tagline', 'subtitle', 'copyright', 'rights', 'description']
    can_contain_dangerous_markup = ['content', 'title', 'summary', 'info', 'tagline', 'subtitle', 'copyright', 'rights', 'description']
    html_types = ['text/html', 'application/xhtml+xml']
    
    def __init__(self, baseuri=None, baselang=None, encoding='utf-8'):
        if _debug: sys.stderr.write('initializing FeedParser\n')
        if not self._matchnamespaces:
            for k, v in self.namespaces.items():
                self._matchnamespaces[k.lower()] = v
        self.feeddata = FeedParserDict() # feed-level data
        self.encoding = encoding # character encoding
        self.entries = [] # list of entry-level data
        self.version = '' # feed type/version, see SUPPORTED_VERSIONS
        self.namespacesInUse = {} # dictionary of namespaces defined by the feed

        # the following are used internally to track state;
        # this is really out of control and should be refactored
        self.infeed = 0
        self.inentry = 0
        self.incontent = 0
        self.intextinput = 0
        self.inimage = 0
        self.inauthor = 0
        self.incontributor = 0
        self.inpublisher = 0
        self.insource = 0
        self.sourcedata = FeedParserDict()
        self.contentparams = FeedParserDict()
        self._summaryKey = None
        self.namespacemap = {}
        self.elementstack = []
        self.basestack = []
        self.langstack = []
        self.baseuri = baseuri or ''
        self.lang = baselang or None
        if baselang:
            self.feeddata['language'] = baselang

    def unknown_starttag(self, tag, attrs):
        if _debug: sys.stderr.write('start %s with %s\n' % (tag, attrs))
        # normalize attrs
        attrs = [(k.lower(), v) for k, v in attrs]
        attrs = [(k, k in ('rel', 'type') and v.lower() or v) for k, v in attrs]
        
        # track xml:base and xml:lang
        attrsD = dict(attrs)
        baseuri = attrsD.get('xml:base', attrsD.get('base')) or self.baseuri
        self.baseuri = _urljoin(self.baseuri, baseuri)
        lang = attrsD.get('xml:lang', attrsD.get('lang'))
        if lang == '':
            # xml:lang could be explicitly set to '', we need to capture that
            lang = None
        elif lang is None:
            # if no xml:lang is specified, use parent lang
            lang = self.lang
        if lang:
            if tag in ('feed', 'rss', 'rdf:RDF'):
                self.feeddata['language'] = lang
        self.lang = lang
        self.basestack.append(self.baseuri)
        self.langstack.append(lang)
        
        # track namespaces
        for prefix, uri in attrs:
            if prefix.startswith('xmlns:'):
                self.trackNamespace(prefix[6:], uri)
            elif prefix == 'xmlns':
                self.trackNamespace(None, uri)

        # track inline content
        if self.incontent and self.contentparams.has_key('type') and not self.contentparams.get('type', 'xml').endswith('xml'):
            # element declared itself as escaped markup, but it isn't really
            self.contentparams['type'] = 'application/xhtml+xml'
        if self.incontent and self.contentparams.get('type') == 'application/xhtml+xml':
            # Note: probably shouldn't simply recreate localname here, but
            # our namespace handling isn't actually 100% correct in cases where
            # the feed redefines the default namespace (which is actually
            # the usual case for inline content, thanks Sam), so here we
            # cheat and just reconstruct the element based on localname
            # because that compensates for the bugs in our namespace handling.
            # This will horribly munge inline content with non-empty qnames,
            # but nobody actually does that, so I'm not fixing it.
            tag = tag.split(':')[-1]
            return self.handle_data('<%s%s>' % (tag, ''.join([' %s="%s"' % t for t in attrs])), escape=0)

        # match namespaces
        if tag.find(':') <> -1:
            prefix, suffix = tag.split(':', 1)
        else:
            prefix, suffix = '', tag
        prefix = self.namespacemap.get(prefix, prefix)
        if prefix:
            prefix = prefix + '_'

        # special hack for better tracking of empty textinput/image elements in illformed feeds
        if (not prefix) and tag not in ('title', 'link', 'description', 'name'):
            self.intextinput = 0
        if (not prefix) and tag not in ('title', 'link', 'description', 'url', 'href', 'width', 'height'):
            self.inimage = 0
        
        # call special handler (if defined) or default handler
        methodname = '_start_' + prefix + suffix
        try:
            method = getattr(self, methodname)
            return method(attrsD)
        except AttributeError:
            return self.push(prefix + suffix, 1)

    def unknown_endtag(self, tag):
        if _debug: sys.stderr.write('end %s\n' % tag)
        # match namespaces
        if tag.find(':') <> -1:
            prefix, suffix = tag.split(':', 1)
        else:
            prefix, suffix = '', tag
        prefix = self.namespacemap.get(prefix, prefix)
        if prefix:
            prefix = prefix + '_'

        # call special handler (if defined) or default handler
        methodname = '_end_' + prefix + suffix
        try:
            method = getattr(self, methodname)
            method()
        except AttributeError:
            self.pop(prefix + suffix)

        # track inline content
        if self.incontent and self.contentparams.has_key('type') and not self.contentparams.get('type', 'xml').endswith('xml'):
            # element declared itself as escaped markup, but it isn't really
            self.contentparams['type'] = 'application/xhtml+xml'
        if self.incontent and self.contentparams.get('type') == 'application/xhtml+xml':
            tag = tag.split(':')[-1]
            self.handle_data('</%s>' % tag, escape=0)

        # track xml:base and xml:lang going out of scope
        if self.basestack:
            self.basestack.pop()
            if self.basestack and self.basestack[-1]:
                self.baseuri = self.basestack[-1]
        if self.langstack:
            self.langstack.pop()
            if self.langstack: # and (self.langstack[-1] is not None):
                self.lang = self.langstack[-1]

    def handle_charref(self, ref):
        # called for each character reference, e.g. for '&#160;', ref will be '160'
        if not self.elementstack: return
        ref = ref.lower()
        if ref in ('34', '38', '39', '60', '62', 'x22', 'x26', 'x27', 'x3c', 'x3e'):
            text = '&#%s;' % ref
        else:
            if ref[0] == 'x':
                c = int(ref[1:], 16)
            else:
                c = int(ref)
            text = unichr(c).encode('utf-8')
        self.elementstack[-1][2].append(text)

    def handle_entityref(self, ref):
        # called for each entity reference, e.g. for '&copy;', ref will be 'copy'
        if not self.elementstack: return
        if _debug: sys.stderr.write('entering handle_entityref with %s\n' % ref)
        if ref in ('lt', 'gt', 'quot', 'amp', 'apos'):
            text = '&%s;' % ref
        else:
            # entity resolution graciously donated by Aaron Swartz
            def name2cp(k):
                import htmlentitydefs
                if hasattr(htmlentitydefs, 'name2codepoint'): # requires Python 2.3
                    return htmlentitydefs.name2codepoint[k]
                k = htmlentitydefs.entitydefs[k]
                if k.startswith('&#') and k.endswith(';'):
                    return int(k[2:-1]) # not in latin-1
                return ord(k)
            try: name2cp(ref)
            except KeyError: text = '&%s;' % ref
            else: text = unichr(name2cp(ref)).encode('utf-8')
        self.elementstack[-1][2].append(text)

    def handle_data(self, text, escape=1):
        # called for each block of plain text, i.e. outside of any tag and
        # not containing any character or entity references
        if not self.elementstack: return
        if escape and self.contentparams.get('type') == 'application/xhtml+xml':
            text = _xmlescape(text)
        self.elementstack[-1][2].append(text)

    def handle_comment(self, text):
        # called for each comment, e.g. <!-- insert message here -->
        pass

    def handle_pi(self, text):
        # called for each processing instruction, e.g. <?instruction>
        pass

    def handle_decl(self, text):
        pass

    def parse_declaration(self, i):
        # override internal declaration handler to handle CDATA blocks
        if _debug: sys.stderr.write('entering parse_declaration\n')
        if self.rawdata[i:i+9] == '<![CDATA[':
            k = self.rawdata.find(']]>', i)
            if k == -1: k = len(self.rawdata)
            self.handle_data(_xmlescape(self.rawdata[i+9:k]), 0)
            return k+3
        else:
            k = self.rawdata.find('>', i)
            return k+1

    def mapContentType(self, contentType):
        contentType = contentType.lower()
        if contentType == 'text':
            contentType = 'text/plain'
        elif contentType == 'html':
            contentType = 'text/html'
        elif contentType == 'xhtml':
            contentType = 'application/xhtml+xml'
        return contentType
    
    def trackNamespace(self, prefix, uri):
        loweruri = uri.lower()
        if (prefix, loweruri) == (None, 'http://my.netscape.com/rdf/simple/0.9/') and not self.version:
            self.version = 'rss090'
        if loweruri == 'http://purl.org/rss/1.0/' and not self.version:
            self.version = 'rss10'
        if loweruri == 'http://www.w3.org/2005/atom' and not self.version:
            self.version = 'atom10'
        if loweruri.find('backend.userland.com/rss') <> -1:
            # match any backend.userland.com namespace
            uri = 'http://backend.userland.com/rss'
            loweruri = uri
        if self._matchnamespaces.has_key(loweruri):
            self.namespacemap[prefix] = self._matchnamespaces[loweruri]
            self.namespacesInUse[self._matchnamespaces[loweruri]] = uri
        else:
            self.namespacesInUse[prefix or ''] = uri

    def resolveURI(self, uri):
        return _urljoin(self.baseuri or '', uri)
    
    def decodeEntities(self, element, data):
        return data

    def push(self, element, expectingText):
        self.elementstack.append([element, expectingText, []])

    def pop(self, element, stripWhitespace=1):
        if not self.elementstack: return
        if self.elementstack[-1][0] != element: return
        
        element, expectingText, pieces = self.elementstack.pop()
        output = ''.join(pieces)
        if stripWhitespace:
            output = output.strip()
        if not expectingText: return output

        # decode base64 content
        if base64 and self.contentparams.get('base64', 0):
            try:
                output = base64.decodestring(output)
            except binascii.Error:
                pass
            except binascii.Incomplete:
                pass
                
        # resolve relative URIs
        if (element in self.can_be_relative_uri) and output:
            output = self.resolveURI(output)
        
        # decode entities within embedded markup
        if not self.contentparams.get('base64', 0):
            output = self.decodeEntities(element, output)

        # remove temporary cruft from contentparams
        try:
            del self.contentparams['mode']