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