| 1 | # -*- coding: iso-8859-1 -*-
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| 2 | """ A SAX2 driver for libxml2, on top of it's XmlReader API
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| 3 |
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| 4 | USAGE
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| 5 | # put this file (drv_libxml2.py) in PYTHONPATH
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| 6 | import xml.sax
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| 7 | reader = xml.sax.make_parser(["drv_libxml2"])
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| 8 | # ...and the rest is standard python sax.
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| 9 |
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| 10 | CAVEATS
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| 11 | - Lexical handlers are supported, except for start/endEntity
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| 12 | (waiting for XmlReader.ResolveEntity) and start/endDTD
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| 13 | - Error callbacks are not exactly synchronous, they tend
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| 14 | to be invoked before the corresponding content callback,
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| 15 | because the underlying reader interface parses
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| 16 | data by chunks of 512 bytes
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| 17 |
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| 18 | TODO
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| 19 | - search for TODO
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| 20 | - some ErrorHandler events (warning)
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| 21 | - some ContentHandler events (setDocumentLocator, skippedEntity)
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| 22 | - EntityResolver (using libxml2.?)
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| 23 | - DTDHandler (if/when libxml2 exposes such node types)
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| 24 | - DeclHandler (if/when libxml2 exposes such node types)
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| 25 | - property_xml_string?
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| 26 | - feature_string_interning?
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| 27 | - Incremental parser
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| 28 | - additional performance tuning:
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| 29 | - one might cache callbacks to avoid some name lookups
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| 30 | - one might implement a smarter way to pass attributes to startElement
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| 31 | (some kind of lazy evaluation?)
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| 32 | - there might be room for improvement in start/endPrefixMapping
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| 33 | - other?
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| 34 |
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| 35 | """
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| 36 |
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| 37 | __author__ = "Stéphane Bidoul <sbi@skynet.be>"
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| 38 | __version__ = "0.3"
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| 39 |
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| 40 | import sys
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| 41 | import codecs
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| 42 |
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| 43 | if sys.version_info[0] < 3:
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| 44 | __author__ = codecs.unicode_escape_decode(__author__)[0]
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| 45 |
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| 46 | StringTypes = (str, unicode)
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| 47 | # libxml2 returns strings as UTF8
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| 48 | _decoder = codecs.lookup("utf8")[1]
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| 49 | def _d(s):
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| 50 | if s is None:
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| 51 | return s
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| 52 | else:
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| 53 | return _decoder(s)[0]
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| 54 | else:
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| 55 | StringTypes = str
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| 56 | # s is Unicode `str` already
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| 57 | def _d(s):
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| 58 | return s
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| 59 |
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| 60 | from xml.sax._exceptions import *
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| 61 | from xml.sax import xmlreader, saxutils
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| 62 | from xml.sax.handler import \
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| 63 | feature_namespaces, \
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| 64 | feature_namespace_prefixes, \
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| 65 | feature_string_interning, \
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| 66 | feature_validation, \
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| 67 | feature_external_ges, \
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| 68 | feature_external_pes, \
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| 69 | property_lexical_handler, \
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| 70 | property_declaration_handler, \
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| 71 | property_dom_node, \
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| 72 | property_xml_string
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| 73 |
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| 74 | try:
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| 75 | import libxml2
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| 76 | except ImportError:
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| 77 | raise SAXReaderNotAvailable("libxml2 not available: " \
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| 78 | "import error was: %s" % sys.exc_info()[1])
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| 79 |
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| 80 | class Locator(xmlreader.Locator):
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| 81 | """SAX Locator adapter for libxml2.xmlTextReaderLocator"""
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| 82 |
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| 83 | def __init__(self,locator):
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| 84 | self.__locator = locator
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| 85 |
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| 86 | def getColumnNumber(self):
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| 87 | "Return the column number where the current event ends."
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| 88 | return -1
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| 89 |
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| 90 | def getLineNumber(self):
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| 91 | "Return the line number where the current event ends."
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| 92 | return self.__locator.LineNumber()
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| 93 |
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| 94 | def getPublicId(self):
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| 95 | "Return the public identifier for the current event."
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| 96 | return None
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| 97 |
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| 98 | def getSystemId(self):
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| 99 | "Return the system identifier for the current event."
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| 100 | return self.__locator.BaseURI()
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| 101 |
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| 102 | class LibXml2Reader(xmlreader.XMLReader):
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| 103 |
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| 104 | def __init__(self):
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| 105 | xmlreader.XMLReader.__init__(self)
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| 106 | # features
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| 107 | self.__ns = 0
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| 108 | self.__nspfx = 0
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| 109 | self.__validate = 0
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| 110 | self.__extparams = 1
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| 111 | # parsing flag
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| 112 | self.__parsing = 0
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| 113 | # additional handlers
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| 114 | self.__lex_handler = None
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| 115 | self.__decl_handler = None
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| 116 | # error messages accumulator
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| 117 | self.__errors = None
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| 118 |
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| 119 | def _errorHandler(self,arg,msg,severity,locator):
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| 120 | if self.__errors is None:
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| 121 | self.__errors = []
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| 122 | self.__errors.append((severity,
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| 123 | SAXParseException(msg,None,
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| 124 | Locator(locator))))
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| 125 |
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| 126 | def _reportErrors(self,fatal):
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| 127 | for severity,exception in self.__errors:
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| 128 | if severity in (libxml2.PARSER_SEVERITY_VALIDITY_WARNING,
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| 129 | libxml2.PARSER_SEVERITY_WARNING):
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| 130 | self._err_handler.warning(exception)
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| 131 | else:
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| 132 | # when fatal is set, the parse will stop;
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| 133 | # we consider that the last error reported
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| 134 | # is the fatal one.
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| 135 | if fatal and exception is self.__errors[-1][1]:
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| 136 | self._err_handler.fatalError(exception)
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| 137 | else:
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| 138 | self._err_handler.error(exception)
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| 139 | self.__errors = None
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| 140 |
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| 141 | def parse(self, source):
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| 142 | self.__parsing = 1
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| 143 | try:
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| 144 | # prepare source and create reader
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| 145 | if isinstance(source, StringTypes):
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| 146 | reader = libxml2.newTextReaderFilename(source)
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| 147 | else:
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| 148 | source = saxutils.prepare_input_source(source)
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| 149 | input = libxml2.inputBuffer(source.getByteStream())
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| 150 | reader = input.newTextReader(source.getSystemId())
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| 151 | reader.SetErrorHandler(self._errorHandler,None)
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| 152 | # configure reader
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| 153 | if self.__extparams:
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| 154 | reader.SetParserProp(libxml2.PARSER_LOADDTD,1)
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| 155 | reader.SetParserProp(libxml2.PARSER_DEFAULTATTRS,1)
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| 156 | reader.SetParserProp(libxml2.PARSER_SUBST_ENTITIES,1)
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| 157 | reader.SetParserProp(libxml2.PARSER_VALIDATE,self.__validate)
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| 158 | else:
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| 159 | reader.SetParserProp(libxml2.PARSER_LOADDTD, 0)
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| 160 | # we reuse attribute maps (for a slight performance gain)
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| 161 | if self.__ns:
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| 162 | attributesNSImpl = xmlreader.AttributesNSImpl({},{})
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| 163 | else:
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| 164 | attributesImpl = xmlreader.AttributesImpl({})
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| 165 | # prefixes to pop (for endPrefixMapping)
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| 166 | prefixes = []
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| 167 | # start loop
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| 168 | self._cont_handler.startDocument()
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| 169 | while 1:
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| 170 | r = reader.Read()
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| 171 | # check for errors
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| 172 | if r == 1:
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| 173 | if not self.__errors is None:
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| 174 | self._reportErrors(0)
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| 175 | elif r == 0:
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| 176 | if not self.__errors is None:
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| 177 | self._reportErrors(0)
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| 178 | break # end of parse
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| 179 | else:
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| 180 | if not self.__errors is None:
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| 181 | self._reportErrors(1)
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| 182 | else:
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| 183 | self._err_handler.fatalError(\
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| 184 | SAXException("Read failed (no details available)"))
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| 185 | break # fatal parse error
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| 186 | # get node type
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| 187 | nodeType = reader.NodeType()
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| 188 | # Element
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| 189 | if nodeType == 1:
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| 190 | if self.__ns:
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| 191 | eltName = (_d(reader.NamespaceUri()),\
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| 192 | _d(reader.LocalName()))
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| 193 | eltQName = _d(reader.Name())
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| 194 | attributesNSImpl._attrs = attrs = {}
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| 195 | attributesNSImpl._qnames = qnames = {}
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| 196 | newPrefixes = []
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| 197 | while reader.MoveToNextAttribute():
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| 198 | qname = _d(reader.Name())
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| 199 | value = _d(reader.Value())
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| 200 | if qname.startswith("xmlns"):
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| 201 | if len(qname) > 5:
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| 202 | newPrefix = qname[6:]
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| 203 | else:
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| 204 | newPrefix = None
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| 205 | newPrefixes.append(newPrefix)
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| 206 | self._cont_handler.startPrefixMapping(\
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| 207 | newPrefix,value)
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| 208 | if not self.__nspfx:
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| 209 | continue # don't report xmlns attribute
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| 210 | attName = (_d(reader.NamespaceUri()),
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| 211 | _d(reader.LocalName()))
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| 212 | qnames[attName] = qname
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| 213 | attrs[attName] = value
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| 214 | reader.MoveToElement()
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| 215 | self._cont_handler.startElementNS( \
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| 216 | eltName,eltQName,attributesNSImpl)
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| 217 | if reader.IsEmptyElement():
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| 218 | self._cont_handler.endElementNS(eltName,eltQName)
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| 219 | for newPrefix in newPrefixes:
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| 220 | self._cont_handler.endPrefixMapping(newPrefix)
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| 221 | else:
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| 222 | prefixes.append(newPrefixes)
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| 223 | else:
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| 224 | eltName = _d(reader.Name())
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| 225 | attributesImpl._attrs = attrs = {}
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| 226 | while reader.MoveToNextAttribute():
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| 227 | attName = _d(reader.Name())
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| 228 | attrs[attName] = _d(reader.Value())
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| 229 | reader.MoveToElement()
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| 230 | self._cont_handler.startElement( \
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| 231 | eltName,attributesImpl)
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| 232 | if reader.IsEmptyElement():
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| 233 | self._cont_handler.endElement(eltName)
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| 234 | # EndElement
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| 235 | elif nodeType == 15:
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| 236 | if self.__ns:
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| 237 | self._cont_handler.endElementNS( \
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| 238 | (_d(reader.NamespaceUri()),_d(reader.LocalName())),
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| 239 | _d(reader.Name()))
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| 240 | for prefix in prefixes.pop():
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| 241 | self._cont_handler.endPrefixMapping(prefix)
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| 242 | else:
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| 243 | self._cont_handler.endElement(_d(reader.Name()))
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| 244 | # Text
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| 245 | elif nodeType == 3:
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| 246 | self._cont_handler.characters(_d(reader.Value()))
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| 247 | # Whitespace
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| 248 | elif nodeType == 13:
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| 249 | self._cont_handler.ignorableWhitespace(_d(reader.Value()))
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| 250 | # SignificantWhitespace
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| 251 | elif nodeType == 14:
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| 252 | self._cont_handler.characters(_d(reader.Value()))
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| 253 | # CDATA
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| 254 | elif nodeType == 4:
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| 255 | if not self.__lex_handler is None:
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| 256 | self.__lex_handler.startCDATA()
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| 257 | self._cont_handler.characters(_d(reader.Value()))
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| 258 | if not self.__lex_handler is None:
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| 259 | self.__lex_handler.endCDATA()
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| 260 | # EntityReference
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| 261 | elif nodeType == 5:
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| 262 | if not self.__lex_handler is None:
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| 263 | self.startEntity(_d(reader.Name()))
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| 264 | reader.ResolveEntity()
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| 265 | # EndEntity
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| 266 | elif nodeType == 16:
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| 267 | if not self.__lex_handler is None:
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| 268 | self.endEntity(_d(reader.Name()))
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| 269 | # ProcessingInstruction
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| 270 | elif nodeType == 7:
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| 271 | self._cont_handler.processingInstruction( \
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| 272 | _d(reader.Name()),_d(reader.Value()))
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| 273 | # Comment
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| 274 | elif nodeType == 8:
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| 275 | if not self.__lex_handler is None:
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| 276 | self.__lex_handler.comment(_d(reader.Value()))
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| 277 | # DocumentType
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| 278 | elif nodeType == 10:
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| 279 | #if not self.__lex_handler is None:
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| 280 | # self.__lex_handler.startDTD()
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| 281 | pass # TODO (how to detect endDTD? on first non-dtd event?)
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| 282 | # XmlDeclaration
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| 283 | elif nodeType == 17:
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| 284 | pass # TODO
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| 285 | # Entity
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| 286 | elif nodeType == 6:
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| 287 | pass # TODO (entity decl)
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| 288 | # Notation (decl)
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| 289 | elif nodeType == 12:
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| 290 | pass # TODO
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| 291 | # Attribute (never in this loop)
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| 292 | #elif nodeType == 2:
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| 293 | # pass
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| 294 | # Document (not exposed)
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| 295 | #elif nodeType == 9:
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| 296 | # pass
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| 297 | # DocumentFragment (never returned by XmlReader)
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| 298 | #elif nodeType == 11:
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| 299 | # pass
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| 300 | # None
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| 301 | #elif nodeType == 0:
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| 302 | # pass
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| 303 | # -
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| 304 | else:
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| 305 | raise SAXException("Unexpected node type %d" % nodeType)
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| 306 | if r == 0:
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| 307 | self._cont_handler.endDocument()
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| 308 | reader.Close()
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| 309 | finally:
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| 310 | self.__parsing = 0
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| 311 |
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| 312 | def setDTDHandler(self, handler):
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| 313 | # TODO (when supported, the inherited method works just fine)
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| 314 | raise SAXNotSupportedException("DTDHandler not supported")
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| 315 |
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| 316 | def setEntityResolver(self, resolver):
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| 317 | # TODO (when supported, the inherited method works just fine)
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| 318 | raise SAXNotSupportedException("EntityResolver not supported")
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| 319 |
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| 320 | def getFeature(self, name):
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| 321 | if name == feature_namespaces:
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| 322 | return self.__ns
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| 323 | elif name == feature_namespace_prefixes:
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| 324 | return self.__nspfx
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| 325 | elif name == feature_validation:
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| 326 | return self.__validate
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| 327 | elif name == feature_external_ges:
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| 328 | return 1 # TODO (does that relate to PARSER_LOADDTD)?
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| 329 | elif name == feature_external_pes:
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| 330 | return self.__extparams
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| 331 | else:
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| 332 | raise SAXNotRecognizedException("Feature '%s' not recognized" % \
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| 333 | name)
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| 334 |
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| 335 | def setFeature(self, name, state):
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| 336 | if self.__parsing:
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| 337 | raise SAXNotSupportedException("Cannot set feature %s " \
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| 338 | "while parsing" % name)
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| 339 | if name == feature_namespaces:
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| 340 | self.__ns = state
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| 341 | elif name == feature_namespace_prefixes:
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| 342 | self.__nspfx = state
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| 343 | elif name == feature_validation:
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| 344 | self.__validate = state
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| 345 | elif name == feature_external_ges:
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| 346 | if state == 0:
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| 347 | # TODO (does that relate to PARSER_LOADDTD)?
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| 348 | raise SAXNotSupportedException("Feature '%s' not supported" % \
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| 349 | name)
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| 350 | elif name == feature_external_pes:
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| 351 | self.__extparams = state
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| 352 | else:
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| 353 | raise SAXNotRecognizedException("Feature '%s' not recognized" % \
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| 354 | name)
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| 355 |
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| 356 | def getProperty(self, name):
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| 357 | if name == property_lexical_handler:
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| 358 | return self.__lex_handler
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| 359 | elif name == property_declaration_handler:
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| 360 | return self.__decl_handler
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| 361 | else:
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| 362 | raise SAXNotRecognizedException("Property '%s' not recognized" % \
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| 363 | name)
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| 364 |
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| 365 | def setProperty(self, name, value):
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| 366 | if name == property_lexical_handler:
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| 367 | self.__lex_handler = value
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| 368 | elif name == property_declaration_handler:
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| 369 | # TODO: remove if/when libxml2 supports dtd events
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| 370 | raise SAXNotSupportedException("Property '%s' not supported" % \
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| 371 | name)
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| 372 | self.__decl_handler = value
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| 373 | else:
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| 374 | raise SAXNotRecognizedException("Property '%s' not recognized" % \
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| 375 | name)
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| 376 |
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| 377 | def create_parser():
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| 378 | return LibXml2Reader()
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| 379 |
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