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xmlreader.py
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380 lines (281 loc) · 12.4 KB
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"""An XML Reader is the SAX 2 name for an XML parser. XML Parsers
should be based on this code. """
from . 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):
from . import saxutils
source = saxutils.prepare_input_source(source)
self.prepareParser(source)
file = source.getCharacterStream()
if file is None:
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 name not in self._attrs:
raise KeyError(name)
return name
def getQNameByName(self, name):
if name not in self._attrs:
raise KeyError(name)
return name
def getNames(self):
return list(self._attrs.keys())
def getQNames(self):
return list(self._attrs.keys())
def __len__(self):
return len(self._attrs)
def __getitem__(self, name):
return self._attrs[name]
def keys(self):
return list(self._attrs.keys())
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 list(self._attrs.items())
def values(self):
return list(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 list(self._qnames.values())
def copy(self):
return self.__class__(self._attrs, self._qnames)
def _test():
XMLReader()
IncrementalParser()
Locator()
if __name__ == "__main__":
_test()