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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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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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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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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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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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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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