Lib/xml/sax/expatreader.py

"""
SAX driver for the Pyexpat C module.  This driver works with
pyexpat.__version__ == '1.5'.
"""

# Todo on driver:
#  - make it support external entities (wait for pyexpat.c)
#  - enable configuration between reset() and feed() calls
#  - support lexical events?
#  - proper inputsource handling
#  - properties and features

# Todo on pyexpat.c:
#  - support XML_ExternalEntityParserCreate
#  - exceptions in callouts from pyexpat to python code lose position info

version = "0.20"

from xml.sax._exceptions import *
from xml.parsers import expat
from xml.sax import xmlreader, saxutils

AttributesImpl = xmlreader.AttributesImpl
AttributesNSImpl = xmlreader.AttributesNSImpl

# --- ExpatParser

class ExpatParser(xmlreader.IncrementalParser, xmlreader.Locator):
    "SAX driver for the Pyexpat C module."

    def __init__(self, namespaceHandling=0, bufsize=2**16-20):
        xmlreader.IncrementalParser.__init__(self, bufsize)
        self._source = None
        self._parser = None
        self._namespaces = namespaceHandling
        self._parsing = 0

    # XMLReader methods

    def parse(self, source):
        "Parse an XML document from a URL."
        source = saxutils.prepare_input_source(source)

        self._source = source
        self.reset()
        self._cont_handler.setDocumentLocator(self)
        try:
            xmlreader.IncrementalParser.parse(self, source)
        except expat.error:
            error_code = self._parser.ErrorCode
            raise SAXParseException(expat.ErrorString(error_code), None, self)
            
            self._cont_handler.endDocument()

    def prepareParser(self, source):
        if source.getSystemId() != None:
            self._parser.SetBase(source.getSystemId())
        
    def getFeature(self, name):
        if name == feature_namespaces:
            return self._namespaces
        raise SAXNotRecognizedException("Feature '%s' not recognized" % name)

    def setFeature(self, name, state):
        if self._parsing:
            raise SAXNotSupportedException("Cannot set features while parsing")
        if name == feature_namespaces:
            self._namespaces = state
        else:
            raise SAXNotRecognizedException("Feature '%s' not recognized" %
                                            name)

    def getProperty(self, name):
        raise SAXNotRecognizedException("Property '%s' not recognized" % name)

    def setProperty(self, name, value):
        raise SAXNotRecognizedException("Property '%s' not recognized" % name)

    # IncrementalParser methods

    def feed(self, data):
        if not self._parsing:
            self._parsing = 1
            self.reset()
            self._cont_handler.startDocument()

        if not self._parser.Parse(data, 0):
            msg = pyexpat.ErrorString(self._parser.ErrorCode)
            raise SAXParseException(msg, None, self)

    def close(self):
        if self._parsing:
            self._cont_handler.endDocument()
            self._parsing = 0
        self._parser.Parse("", 1)
        
    def reset(self):
        if self._namespaces:
            self._parser = expat.ParserCreate(None, " ")
            self._parser.StartElementHandler = self.start_element_ns
            self._parser.EndElementHandler = self.end_element_ns
        else:
            self._parser = expat.ParserCreate()
            self._parser.StartElementHandler = self.start_element
            self._parser.EndElementHandler = self.end_element

        self._parser.ProcessingInstructionHandler = \
                                    self._cont_handler.processingInstruction
        self._parser.CharacterDataHandler = self._cont_handler.characters
        self._parser.UnparsedEntityDeclHandler = self.unparsed_entity_decl
        self._parser.NotationDeclHandler = self.notation_decl
        self._parser.StartNamespaceDeclHandler = self.start_namespace_decl
        self._parser.EndNamespaceDeclHandler = self.end_namespace_decl
#         self._parser.CommentHandler = 
#         self._parser.StartCdataSectionHandler = 
#         self._parser.EndCdataSectionHandler = 
#         self._parser.DefaultHandler = 
#         self._parser.DefaultHandlerExpand = 
#         self._parser.NotStandaloneHandler = 
        self._parser.ExternalEntityRefHandler = self.external_entity_ref
    
    # Locator methods

    def getColumnNumber(self):
        return self._parser.ErrorColumnNumber

    def getLineNumber(self):
        return self._parser.ErrorLineNumber

    def getPublicId(self):
        return self._source.getPublicId()

    def getSystemId(self):
        return self._parser.GetBase()
    
    # event handlers
    def start_element(self, name, attrs):
        self._cont_handler.startElement(name, AttributesImpl(attrs))

    def end_element(self, name):
        self._cont_handler.endElement(name)

    def start_element_ns(self, name, attrs):
        pair = name.split()
        if len(pair) == 1:
            pair = (None, name)

        newattrs = {}
        for (aname, value) in attrs.items():
            apair = aname.split()
            if len(apair) == 1:
                apair = (None, aname)
            else:
                apair = tuple(apair)

            newattrs[apair] = value

        self._cont_handler.startElementNS(pair, None, 
                                          AttributesNSImpl(newattrs, {}))

    def end_element_ns(self, name):
        pair = name.split()
        if len(pair) == 1:
            pair = (None, name)
            
        self._cont_handler.endElementNS(pair, None)

    # this is not used (call directly to ContentHandler)
    def processing_instruction(self, target, data):
        self._cont_handler.processingInstruction(target, data)

    # this is not used (call directly to ContentHandler)
    def character_data(self, data):
        self._cont_handler.characters(data)

    def start_namespace_decl(self, prefix, uri):
        self._cont_handler.startPrefixMapping(prefix, uri)

    def end_namespace_decl(self, prefix):
        self._cont_handler.endPrefixMapping(prefix)
        
    def unparsed_entity_decl(self, name, base, sysid, pubid, notation_name):
        self._dtd_handler.unparsedEntityDecl(name, pubid, sysid, notation_name)

    def notation_decl(self, name, base, sysid, pubid):
        self._dtd_handler.notationDecl(name, pubid, sysid)

    def external_entity_ref(self, context, base, sysid, pubid):
        raise NotImplementedError()
        source = self._ent_handler.resolveEntity(pubid, sysid)
        source = saxutils.prepare_input_source(source)
        # FIXME: create new parser, stack self._source and self._parser
        # FIXME: reuse code from self.parse(...)
        return 1
        
# ---
        
def create_parser(*args, **kwargs):
    return apply(ExpatParser, args, kwargs)
        
# ---

if __name__ == "__main__":
    import xml.sax
    p = create_parser()
    p.setContentHandler(xml.sax.XMLGenerator())
    p.setErrorHandler(xml.sax.ErrorHandler())
    p.parse("../../../hamlet.xml")