381 lines
12 KiB
Python
381 lines
12 KiB
Python
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"""An XML Reader is the SAX 2 name for an XML parser. XML Parsers
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should be based on this code. """
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from . import handler
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from ._exceptions import SAXNotSupportedException, SAXNotRecognizedException
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# ===== XMLREADER =====
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class XMLReader:
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"""Interface for reading an XML document using callbacks.
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XMLReader is the interface that an XML parser's SAX2 driver must
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implement. This interface allows an application to set and query
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features and properties in the parser, to register event handlers
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for document processing, and to initiate a document parse.
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All SAX interfaces are assumed to be synchronous: the parse
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methods must not return until parsing is complete, and readers
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must wait for an event-handler callback to return before reporting
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the next event."""
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def __init__(self):
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self._cont_handler = handler.ContentHandler()
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self._dtd_handler = handler.DTDHandler()
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self._ent_handler = handler.EntityResolver()
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self._err_handler = handler.ErrorHandler()
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def parse(self, source):
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"Parse an XML document from a system identifier or an InputSource."
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raise NotImplementedError("This method must be implemented!")
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def getContentHandler(self):
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"Returns the current ContentHandler."
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return self._cont_handler
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def setContentHandler(self, handler):
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"Registers a new object to receive document content events."
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self._cont_handler = handler
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def getDTDHandler(self):
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"Returns the current DTD handler."
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return self._dtd_handler
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def setDTDHandler(self, handler):
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"Register an object to receive basic DTD-related events."
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self._dtd_handler = handler
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def getEntityResolver(self):
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"Returns the current EntityResolver."
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return self._ent_handler
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def setEntityResolver(self, resolver):
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"Register an object to resolve external entities."
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self._ent_handler = resolver
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def getErrorHandler(self):
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"Returns the current ErrorHandler."
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return self._err_handler
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def setErrorHandler(self, handler):
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"Register an object to receive error-message events."
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self._err_handler = handler
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def setLocale(self, locale):
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"""Allow an application to set the locale for errors and warnings.
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SAX parsers are not required to provide localization for errors
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and warnings; if they cannot support the requested locale,
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however, they must raise a SAX exception. Applications may
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request a locale change in the middle of a parse."""
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raise SAXNotSupportedException("Locale support not implemented")
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def getFeature(self, name):
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"Looks up and returns the state of a SAX2 feature."
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raise SAXNotRecognizedException("Feature '%s' not recognized" % name)
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def setFeature(self, name, state):
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"Sets the state of a SAX2 feature."
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raise SAXNotRecognizedException("Feature '%s' not recognized" % name)
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def getProperty(self, name):
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"Looks up and returns the value of a SAX2 property."
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raise SAXNotRecognizedException("Property '%s' not recognized" % name)
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def setProperty(self, name, value):
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"Sets the value of a SAX2 property."
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raise SAXNotRecognizedException("Property '%s' not recognized" % name)
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class IncrementalParser(XMLReader):
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"""This interface adds three extra methods to the XMLReader
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interface that allow XML parsers to support incremental
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parsing. Support for this interface is optional, since not all
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underlying XML parsers support this functionality.
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When the parser is instantiated it is ready to begin accepting
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data from the feed method immediately. After parsing has been
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finished with a call to close the reset method must be called to
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make the parser ready to accept new data, either from feed or
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using the parse method.
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Note that these methods must _not_ be called during parsing, that
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is, after parse has been called and before it returns.
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By default, the class also implements the parse method of the XMLReader
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interface using the feed, close and reset methods of the
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IncrementalParser interface as a convenience to SAX 2.0 driver
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writers."""
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def __init__(self, bufsize=2**16):
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self._bufsize = bufsize
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XMLReader.__init__(self)
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def parse(self, source):
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from . import saxutils
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source = saxutils.prepare_input_source(source)
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self.prepareParser(source)
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file = source.getCharacterStream()
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if file is None:
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file = source.getByteStream()
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buffer = file.read(self._bufsize)
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while buffer:
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self.feed(buffer)
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buffer = file.read(self._bufsize)
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self.close()
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def feed(self, data):
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"""This method gives the raw XML data in the data parameter to
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the parser and makes it parse the data, emitting the
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corresponding events. It is allowed for XML constructs to be
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split across several calls to feed.
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feed may raise SAXException."""
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raise NotImplementedError("This method must be implemented!")
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def prepareParser(self, source):
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"""This method is called by the parse implementation to allow
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the SAX 2.0 driver to prepare itself for parsing."""
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raise NotImplementedError("prepareParser must be overridden!")
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def close(self):
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"""This method is called when the entire XML document has been
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passed to the parser through the feed method, to notify the
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parser that there are no more data. This allows the parser to
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do the final checks on the document and empty the internal
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data buffer.
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The parser will not be ready to parse another document until
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the reset method has been called.
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close may raise SAXException."""
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raise NotImplementedError("This method must be implemented!")
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def reset(self):
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"""This method is called after close has been called to reset
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the parser so that it is ready to parse new documents. The
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results of calling parse or feed after close without calling
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reset are undefined."""
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raise NotImplementedError("This method must be implemented!")
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# ===== LOCATOR =====
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class Locator:
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"""Interface for associating a SAX event with a document
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location. A locator object will return valid results only during
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calls to DocumentHandler methods; at any other time, the
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results are unpredictable."""
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def getColumnNumber(self):
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"Return the column number where the current event ends."
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return -1
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def getLineNumber(self):
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"Return the line number where the current event ends."
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return -1
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def getPublicId(self):
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"Return the public identifier for the current event."
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return None
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def getSystemId(self):
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"Return the system identifier for the current event."
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return None
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# ===== INPUTSOURCE =====
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class InputSource:
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"""Encapsulation of the information needed by the XMLReader to
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read entities.
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This class may include information about the public identifier,
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system identifier, byte stream (possibly with character encoding
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information) and/or the character stream of an entity.
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Applications will create objects of this class for use in the
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XMLReader.parse method and for returning from
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EntityResolver.resolveEntity.
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An InputSource belongs to the application, the XMLReader is not
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allowed to modify InputSource objects passed to it from the
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application, although it may make copies and modify those."""
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def __init__(self, system_id = None):
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self.__system_id = system_id
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self.__public_id = None
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self.__encoding = None
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self.__bytefile = None
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self.__charfile = None
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def setPublicId(self, public_id):
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"Sets the public identifier of this InputSource."
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self.__public_id = public_id
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def getPublicId(self):
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"Returns the public identifier of this InputSource."
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return self.__public_id
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def setSystemId(self, system_id):
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"Sets the system identifier of this InputSource."
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self.__system_id = system_id
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def getSystemId(self):
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"Returns the system identifier of this InputSource."
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return self.__system_id
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def setEncoding(self, encoding):
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"""Sets the character encoding of this InputSource.
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The encoding must be a string acceptable for an XML encoding
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declaration (see section 4.3.3 of the XML recommendation).
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The encoding attribute of the InputSource is ignored if the
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InputSource also contains a character stream."""
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self.__encoding = encoding
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def getEncoding(self):
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"Get the character encoding of this InputSource."
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return self.__encoding
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def setByteStream(self, bytefile):
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"""Set the byte stream (a Python file-like object which does
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not perform byte-to-character conversion) for this input
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source.
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The SAX parser will ignore this if there is also a character
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stream specified, but it will use a byte stream in preference
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to opening a URI connection itself.
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If the application knows the character encoding of the byte
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stream, it should set it with the setEncoding method."""
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self.__bytefile = bytefile
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def getByteStream(self):
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"""Get the byte stream for this input source.
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The getEncoding method will return the character encoding for
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this byte stream, or None if unknown."""
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return self.__bytefile
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def setCharacterStream(self, charfile):
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"""Set the character stream for this input source. (The stream
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must be a Python 2.0 Unicode-wrapped file-like that performs
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conversion to Unicode strings.)
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If there is a character stream specified, the SAX parser will
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ignore any byte stream and will not attempt to open a URI
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connection to the system identifier."""
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self.__charfile = charfile
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def getCharacterStream(self):
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"Get the character stream for this input source."
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return self.__charfile
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# ===== ATTRIBUTESIMPL =====
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class AttributesImpl:
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def __init__(self, attrs):
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"""Non-NS-aware implementation.
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attrs should be of the form {name : value}."""
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self._attrs = attrs
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def getLength(self):
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return len(self._attrs)
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def getType(self, name):
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return "CDATA"
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def getValue(self, name):
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return self._attrs[name]
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def getValueByQName(self, name):
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return self._attrs[name]
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def getNameByQName(self, name):
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if name not in self._attrs:
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raise KeyError(name)
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return name
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def getQNameByName(self, name):
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if name not in self._attrs:
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raise KeyError(name)
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return name
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def getNames(self):
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return list(self._attrs.keys())
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def getQNames(self):
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return list(self._attrs.keys())
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def __len__(self):
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return len(self._attrs)
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def __getitem__(self, name):
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return self._attrs[name]
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def keys(self):
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return list(self._attrs.keys())
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def __contains__(self, name):
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return name in self._attrs
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def get(self, name, alternative=None):
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return self._attrs.get(name, alternative)
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def copy(self):
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return self.__class__(self._attrs)
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def items(self):
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return list(self._attrs.items())
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def values(self):
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return list(self._attrs.values())
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# ===== ATTRIBUTESNSIMPL =====
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class AttributesNSImpl(AttributesImpl):
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def __init__(self, attrs, qnames):
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"""NS-aware implementation.
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attrs should be of the form {(ns_uri, lname): value, ...}.
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qnames of the form {(ns_uri, lname): qname, ...}."""
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self._attrs = attrs
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self._qnames = qnames
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def getValueByQName(self, name):
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for (nsname, qname) in self._qnames.items():
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if qname == name:
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return self._attrs[nsname]
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raise KeyError(name)
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def getNameByQName(self, name):
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for (nsname, qname) in self._qnames.items():
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if qname == name:
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return nsname
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raise KeyError(name)
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def getQNameByName(self, name):
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return self._qnames[name]
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def getQNames(self):
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return list(self._qnames.values())
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def copy(self):
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return self.__class__(self._attrs, self._qnames)
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def _test():
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XMLReader()
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IncrementalParser()
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Locator()
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if __name__ == "__main__":
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_test()
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