[XML-SIG] SAX2.py
uche.ogbuji@fourthought.com
uche.ogbuji@fourthought.com
Mon, 04 Oct 1999 01:41:08 -0400
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Ok Folks,
There's pretty much no way to run a SAX-based XSLT interface from SAX classic,
and building DOM therefrom is just a mess. I can't really wait for SAX2 to
finish incubating, and I don't expect earth-levelling changes, so I went and
wrote a Python module for SAX2 in its current drafts.
The module is attached. It could easily go into CVS for experimentation: we
will certainly be using these interfaces in 4DOM and 4XSLT. I'd appreciate
any discussion, and if it merits it, Andrew, Lars, or someone could check it
into the xml-SIG CVS.
--
Uche Ogbuji
FourThought LLC, IT Consultants
uche.ogbuji@fourthought.com (970)481-0805
Software engineering, project management, Intranets and Extranets
http://FourThought.com http://OpenTechnology.org
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Content-Type: text/plain; name="Sax2Lib.py"; charset=us-ascii
Content-Description: Sax2Lib.py
Content-Disposition: attachment; filename="Sax2Lib.py"
"""A Python translation of the SAX2 parser API. This file provides only
default classes with absolutely minimum functionality, from which
drivers and applications can be subclassed.
Many of these classes are empty and are included only as documentation
of the interfaces.
"""
from xml.sax import saxlib
class LexicalHandler:
"""
Default handler for lexical events
Note: All methods can raise SAXException
"""
handlerId = 'http://xml.org/sax/handlers/lexical'
def xmlDecl(self, version, encoding, standalone):
"""The XML Declaration"""
pass
def startDTD(self, doctype, publicID, systemID):
"""Invoked at the beginning of the DOCTYPE declaration"""
pass
def endDTD(self):
"""
Invoked after all components of the DOCTYPE declaration,
including both internal and external DTD subsets
"""
pass
def startEntity(self, name):
"""
Note: If an external DTD subset is read, it will invoke this method
with special entity name of "[DTD]"
"""
pass
def endEntity(self, name):
pass
def comment(self, text):
"""XML Comment"""
pass
def startCDATA(self):
"""Beginning of CDATA Section"""
pass
def endCDATA(self):
"""End of CDATA Section"""
pass
class AttributeList2(saxlib. AttributeList):
def isSpecified(self, id):
"""
Whether the attribute value with the given name or index was
explicitly specified in the element, or was determined from the
default. Parameter can be either integer index or attribute name.
None (the default) signals "Don't Know", else a boolean return
"""
pass
def getEntityRefList(self, id):
"""
XML 1,0 parsers are required to report all entity references,
even if unexpanded. This includes those in attribute strings.
Many parsers and apps ignore this, but for full conformance,
This method can be called to get a list of indexes referring
to entity references within the attribute value string for the
given name or index. Parameter can be either integer index or
attribute name.
"""
pass
class EntityRefList:
"""
This is the entity-reference list returned by
AttributeList2.getEntityRefList(index)
"""
def getLength(self):
"Return the number of Entity Ref pointers"
pass
def getEntityName(self, index):
"Return the name of the entity reference at the given index"
pass
def getEntityRefStart(self, index):
"""
Return the string start position of the entity reference
at the given index
"""
pass
def getEntityRefEnd(self, index):
"""
Return the string end position of the entity reference
at the given index
"""
pass
def __len__(self):
"Alias for getLength."
pass
class DTDDeclHandler:
"""
A handler for a minimal set of DTD Events
"""
MODEL_ELEMENTS = 1
MODEL_MIXED = 2
MODEL_ANY = 3
MODEL_EMPTY = 4
ATTRIBUTE_DEFAULTED = 1
ATTRIBUTE_IMPLIED = 2
ATTRIBUTE_REQUIRED = 3
ATTRIBUTE_FIXED = 4
handlerId = 'http://xml.org/sax/handlers/dtd-decl'
def elementDecl(self, name, modelType, model):
"""
Report an element-type declaration.
name and model are strings, modelType is an enumerated int from 1 to 4
"""
pass
def attributeDecl(self,
element,
name,
type,
defaultValue,
defaultType,
entityRefs):
"""
Report an attribute declaration. The first 4 parameters are strings,
defaultType is an integer from 1 to 4, entityRefs is an EntityRefList
"""
pass
def externalEntityDecl(self, name, isParameterEntity, publicId, systemId):
"""
Report an external entity declaration.
All parameters are strings except for isParameterEntity,
which is 0 or 1
"""
pass
def internalEntityDecl(self, name, isParameterEntity, value):
"""
Report an external entity declaration.
All parameters are strings except for isParameterEntity,
which is 0 or 1
"""
pass
class NamespaceHandler:
"""
Receive callbacks for the start and end of the scope of each
namespace declaration.
"""
handlerId = 'http://xml.org/sax/handlers/namespace'
def startNamespaceDeclScope(prefix, uri):
"""
Report the start of the scope of a namespace declaration.
This event will be reported before the startElement event
for the element containing the namespace declaration. All
declarations must be properly nested; if there are multiple
declarations in a single element, they must end in the opposite
order that they began.
both parameters are strings
"""
pass
def endNamespaceDeclScope(prefix):
"""
Report the end of the scope of a namespace declaration.
This event will be reported after the endElement event for
the element containing the namespace declaration. Namespace
scopes must be properly nested.
"""
pass
class ModParser(saxlib.Parser):
"""
All methods may raise
SAXNotSupportedException
"""
def setFeature(self, featureID, state):
"""
featureId is a string, state a boolean
"""
pass
def setHandler(self, handlerID, handler):
"""
handlerID is a string, handler a handler instance
"""
pass
def set(self, propID, value):
"""
propID is a string, value of arbitrary type
"""
pass
def get(self, propID):
pass
import sys
if sys.platform[0:4] == 'java':
from exceptions import Exception
class SAXNotSupportedException(Exception):
"""
Indicate that a SAX2 parser interface does not support a particular
feature or handler, or property.
"""
pass
#Just a few helper lists with the core components
CoreHandlers = [
'http://xml.org/sax/handlers/lexical',
'http://xml.org/sax/handlers/dtd-decl',
'http://xml.org/sax/handlers/namespace'
]
CoreProperties = [
'http://xml.org/sax/properties/namespace-sep',
#write-only string
#Set the separator to be used between the URI part of a name and the
#local part of a name when namespace processing is being performed
#(see the http://xml.org/sax/features/namespaces feature). By
#default, the separator is a single space. This property may not be
#set while a parse is in progress (raises SAXNotSupportedException).
'http://xml.org/sax/properties/dom-node',
#read-only Node instance
#Get the DOM node currently being visited, if the SAX parser is
#iterating over a DOM tree. If the parser recognises and supports
#this property but is not currently visiting a DOM node, it should
#return null (this is a good way to check for availability before the
#parse begins).
'http://xml.org/sax/properties/xml-string'
#read-only string
#Get the literal string of characters associated with the current
#event. If the parser recognises and supports this property but is
#not currently parsing text, it should return null (this is a good
#way to check for availability before the parse begins).
]
CoreFeatures = [
'http://xml.org/sax/features/validation',
#Validate (1) or don't validate (0).
'http://xml.org/sax/features/external-general-entities',
#Expand external general entities (1) or don't expand (0).
'http://xml.org/sax/features/external-parameter-entities',
#Expand external parameter entities (1) or don't expand (0).
'http://xml.org/sax/features/namespaces',
#Preprocess namespaces (1) or don't preprocess (0). See also
#the http://xml.org/sax/properties/namespace-sep property.
'http://xml.org/sax/features/normalize-text'
#Ensure that all consecutive text is returned in a single callback to
#DocumentHandler.characters or DocumentHandler.ignorableWhitespace
#(1) or explicitly do not require it (0).
]
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