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expatbuilder.py
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"""Facility to use the Expat parser to load a minidom instance from a string or file. This avoids all the overhead of SAX and pulldom to gain performance. """ # Warning! # # This module is tightly bound to the implementation details of the # minidom DOM and can't be used with other DOM implementations. This # is due, in part, to a lack of appropriate methods in the DOM (there is # no way to create Entity and Notation nodes via the DOM Level 2 # interface), and for performance. The latter is the cause of some fairly # cryptic code. # # Performance hacks: # # - .character_data_handler() has an extra case in which continuing # data is appended to an existing Text node; this can be a # speedup since pyexpat can break up character data into multiple # callbacks even though we set the buffer_text attribute on the # parser. This also gives us the advantage that we don't need a # separate normalization pass. # # - Determining that a node exists is done using an identity comparison # with None rather than a truth test; this avoids searching for and # calling any methods on the node object if it exists. (A rather # nice speedup is achieved this way as well!) from xml.dom import xmlbuilder, minidom, Node from xml.dom import EMPTY_NAMESPACE, EMPTY_PREFIX, XMLNS_NAMESPACE from xml.parsers import expat from xml.dom.minidom import _append_child, _set_attribute_node from xml.dom.NodeFilter import NodeFilter from xml.dom.minicompat import * TEXT_NODE = Node.TEXT_NODE CDATA_SECTION_NODE = Node.CDATA_SECTION_NODE DOCUMENT_NODE = Node.DOCUMENT_NODE FILTER_ACCEPT = xmlbuilder.DOMBuilderFilter.FILTER_ACCEPT FILTER_REJECT = xmlbuilder.DOMBuilderFilter.FILTER_REJECT FILTER_SKIP = xmlbuilder.DOMBuilderFilter.FILTER_SKIP FILTER_INTERRUPT = xmlbuilder.DOMBuilderFilter.FILTER_INTERRUPT theDOMImplementation = minidom.getDOMImplementation() # Expat typename -> TypeInfo _typeinfo_map = { "CDATA": minidom.TypeInfo(None, "cdata"), "ENUM": minidom.TypeInfo(None, "enumeration"), "ENTITY": minidom.TypeInfo(None, "entity"), "ENTITIES": minidom.TypeInfo(None, "entities"), "ID": minidom.TypeInfo(None, "id"), "IDREF": minidom.TypeInfo(None, "idref"), "IDREFS": minidom.TypeInfo(None, "idrefs"), "NMTOKEN": minidom.TypeInfo(None, "nmtoken"), "NMTOKENS": minidom.TypeInfo(None, "nmtokens"), } class ElementInfo(object): __slots__ = '_attr_info', '_model', 'tagName' def __init__(self, tagName, model=None): self.tagName = tagName self._attr_info = [] self._model = model def __getstate__(self): return self._attr_info, self._model, self.tagName def __setstate__(self, state): self._attr_info, self._model, self.tagName = state def getAttributeType(self, aname): for info in self._attr_info: if info[1] == aname: t = info[-2] if t[0] == "(": return _typeinfo_map["ENUM"] else: return _typeinfo_map[info[-2]] return minidom._no_type def getAttributeTypeNS(self, namespaceURI, localName): return minidom._no_type def isElementContent(self): if self._model: type = self._model[0] return type not in (expat.model.XML_CTYPE_ANY, expat.model.XML_CTYPE_MIXED) else: return False def isEmpty(self): if self._model: return self._model[0] == expat.model.XML_CTYPE_EMPTY else: return False def isId(self, aname): for info in self._attr_info: if info[1] == aname: return info[-2] == "ID" return False def isIdNS(self, euri, ename, auri, aname): # not sure this is meaningful return self.isId((auri, aname)) def _intern(builder, s): return builder._intern_setdefault(s, s) def _parse_ns_name(builder, name): assert ' ' in name parts = name.split(' ') intern = builder._intern_setdefault if len(parts) == 3: uri, localname, prefix = parts prefix = intern(prefix, prefix) qname = "%s:%s" % (prefix, localname) qname = intern(qname, qname) localname = intern(localname, localname) else: uri, localname = parts prefix = EMPTY_PREFIX qname = localname = intern(localname, localname) return intern(uri, uri), localname, prefix, qname class ExpatBuilder: """Document builder that uses Expat to build a ParsedXML.DOM document instance.""" def __init__(self, options=None): if options is None: options = xmlbuilder.Options() self._options = options if self._options.filter is not None: self._filter = FilterVisibilityController(self._options.filter) else: self._filter = None # This *really* doesn't do anything in this case, so # override it with something fast & minimal. self._finish_start_element = id self._parser = None self.reset() def createParser(self): """Create a new parser object.""" return expat.ParserCreate() def getParser(self): """Return the parser object, creating a new one if needed.""" if not self._parser: self._parser = self.createParser() self._intern_setdefault = self._parser.intern.setdefault self._parser.buffer_text = True self._parser.ordered_attributes = True self._parser.specified_attributes = True self.install(self._parser) return self._parser def reset(self): """Free all data structures used during DOM construction.""" self.document = theDOMImplementation.createDocument( EMPTY_NAMESPACE, None, None) self.curNode = self.document self._elem_info = self.document._elem_info self._cdata = False def install(self, parser): """Install the callbacks needed to build the DOM into the parser.""" # This creates circular references! parser.StartDoctypeDeclHandler = self.start_doctype_decl_handler parser.StartElementHandler = self.first_element_handler parser.EndElementHandler = self.end_element_handler parser.ProcessingInstructionHandler = self.pi_handler if self._options.entities: parser.EntityDeclHandler = self.entity_decl_handler parser.NotationDeclHandler = self.notation_decl_handler if self._options.comments: parser.CommentHandler = self.comment_handler if self._options.cdata_sections: parser.StartCdataSectionHandler = self.start_cdata_section_handler parser.EndCdataSectionHandler = self.end_cdata_section_handler parser.CharacterDataHandler = self.character_data_handler_cdata else: parser.CharacterDataHandler = self.character_data_handler parser.ExternalEntityRefHandler = self.external_entity_ref_handler parser.XmlDeclHandler = self.xml_decl_handler parser.ElementDeclHandler = self.element_decl_handler parser.AttlistDeclHandler = self.attlist_decl_handler def parseFile(self, file): """Parse a document from a file object, returning the document node.""" parser = self.getParser() first_buffer = True try: while 1: buffer = file.read(16*1024) if not buffer: break parser.Parse(buffer, 0) if first_buffer and self.document.documentElement: self._setup_subset(buffer) first_buffer = False parser.Parse("", True) except ParseEscape: pass doc = self.document self.reset() self._parser = None return doc def parseString(self, string): """Parse a document from a string, returning the document node.""" parser = self.getParser() try: parser.Parse(string, True) self._setup_subset(string) except ParseEscape: pass doc = self.document self.reset() self._parser = None return doc def _setup_subset(self, buffer): """Load the internal subset if there might be one.""" if self.document.doctype: extractor = InternalSubsetExtractor() extractor.parseString(buffer) subset = extractor.getSubset() self.document.doctype.internalSubset = subset def start_doctype_decl_handler(self, doctypeName, systemId, publicId, has_internal_subset): doctype = self.document.implementation.createDocumentType( doctypeName, publicId, systemId) doctype.ownerDocument = self.document _append_child(self.document, doctype) self.document.doctype = doctype if self._filter and self._filter.acceptNode(doctype) == FILTER_REJECT: self.document.doctype = None del self.document.childNodes[-1] doctype = None self._parser.EntityDeclHandler = None self._parser.NotationDeclHandler = None if has_internal_subset: if doctype is not None: doctype.entities._seq = [] doctype.notations._seq = [] self._parser.CommentHandler = None self._parser.ProcessingInstructionHandler = None self._parser.EndDoctypeDeclHandler = self.end_doctype_decl_handler def end_doctype_decl_handler(self): if self._options.comments: self._parser.CommentHandler = self.comment_handler self._parser.ProcessingInstructionHandler = self.pi_handler if not (self._elem_info or self._filter): self._finish_end_element = id def pi_handler(self, target, data): node = self.document.createProcessingInstruction(target, data) _append_child(self.curNode, node) if self._filter and self._filter.acceptNode(node) == FILTER_REJECT: self.curNode.removeChild(node) def character_data_handler_cdata(self, data): childNodes = self.curNode.childNodes if self._cdata: if ( self._cdata_continue and childNodes[-1].nodeType == CDATA_SECTION_NODE): childNodes[-1].appendData(data) return node = self.document.createCDATASection(data) self._cdata_continue = True elif childNodes and childNodes[-1].nodeType == TEXT_NODE: node = childNodes[-1] value = node.data + data d = node.__dict__ d['data'] = d['nodeValue'] = value return else: node = minidom.Text() d = node.__dict__ d['data'] = d['nodeValue'] = data d['ownerDocument'] = self.document _append_child(self.curNode, node) def character_data_handler(self, data): childNodes = self.curNode.childNodes if childNodes and childNodes[-1].nodeType == TEXT_NODE: node = childNodes[-1] d = node.__dict__ d['data'] = d['nodeValue'] = node.data + data return node = minidom.Text() d = node.__dict__ d['data'] = d['nodeValue'] = node.data + data d['ownerDocument'] = self.document _append_child(self.curNode, node) def entity_decl_handler(self, entityName, is_parameter_entity, value, base, systemId, publicId, notationName): if is_parameter_entity: # we don't care about parameter entities for the DOM return if not self._options.entities: return node = self.document._create_entity(entityName, publicId, systemId, notationName) if value is not None: # internal entity # node *should* be readonly, but we'll cheat child = self.document.createTextNode(value) node.childNodes.append(child) self.document.doctype.entities._seq.append(node) if self._filter and self._filter.acceptNode(node) == FILTER_REJECT: del self.document.doctype.entities._seq[-1] def notation_decl_handler(self, notationName, base, systemId, publicId): node = self.document._create_notation(notationName, publicId, systemId) self.document.doctype.notations._seq.append(node) if self._filter and self._filter.acceptNode(node) == FILTER_ACCEPT: del self.document.doctype.notations._seq[-1] def comment_handler(self, data): node = self.document.createComment(data) _append_child(self.curNode, node) if self._filter and self._filter.acceptNode(node) == FILTER_REJECT: self.curNode.removeChild(node) def start_cdata_section_handler(self): self._cdata = True self._cdata_continue = False def end_cdata_section_handler(self): self._cdata = False self._cdata_continue = False def external_entity_ref_handler(self, context, base, systemId, publicId): return 1 def first_element_handler(self, name, attributes): if self._filter is None and not self._elem_info: self._finish_end_element = id self.getParser().StartElementHandler = self.start_element_handler self.start_element_handler(name, attributes) def start_element_handler(self, name, attributes): node = self.document.createElement(name) _append_child(self.curNode, node) self.curNode = node if attributes: for i in range(0, len(attributes), 2): a = minidom.Attr(attributes[i], EMPTY_NAMESPACE, None, EMPTY_PREFIX) value = attributes[i+1] d = a.childNodes[0].__dict__ d['data'] = d['nodeValue'] = value d = a.__dict__ d['value'] = d['nodeValue'] = value d['ownerDocument'] = self.document _set_attribute_node(node, a) if node is not self.document.documentElement: self._finish_start_element(node) def _finish_start_element(self, node): if self._filter: # To be general, we'd have to call isSameNode(), but this # is sufficient for minidom: if node is self.document.documentElement: return filt = self._filter.startContainer(node) if filt == FILTER_REJECT: # ignore this node & all descendents Rejecter(self) elif filt == FILTER_SKIP: # ignore this node, but make it's children become # children of the parent node Skipper(self) else: return self.curNode = node.parentNode node.parentNode.removeChild(node) node.unlink() # If this ever changes, Namespaces.end_element_handler() needs to # be changed to match. # def end_element_handler(self, name): curNode = self.curNode self.curNode = curNode.parentNode self._finish_end_element(curNode) def _finish_end_element(self, curNode): info = self._elem_info.get(curNode.tagName) if info: self._handle_white_text_nodes(curNode, info) if self._filter: if curNode is self.document.documentElement: return if self._filter.acceptNode(curNode) == FILTER_REJECT: self.curNode.removeChild(curNode) curNode.unlink() def _handle_white_text_nodes(self, node, info): if (self._options.whitespace_in_element_content or not info.isElementContent()): return # We have element type information and should remove ignorable # whitespace; identify for text nodes which contain only # whitespace. L = [] for child in node.childNodes: if child.nodeType == TEXT_NODE and not child.data.strip(): L.append(child) # Remove ignorable whitespace from the tree. for child in L: node.removeChild(child) def element_decl_handler(self, name, model): info = self._elem_info.get(name) if info is None: self._elem_info[name] = ElementInfo(name, model) else: assert info._model is None info._model = model def attlist_decl_handler(self, elem, name, type, default, required): info = self._elem_info.get(elem) if info is None: info = ElementInfo(elem) self._elem_info[elem] = info info._attr_info.append( [None, name, None, None, default, 0, type, required]) def xml_decl_handler(self, version, encoding, standalone): self.document.version = version self.document.encoding = encoding # This is still a little ugly, thanks to the pyexpat API. ;-( if standalone >= 0: if standalone: self.document.standalone = True else: self.document.standalone = False # Don't include FILTER_INTERRUPT, since that's checked separately # where allowed. _ALLOWED_FILTER_RETURNS = (FILTER_ACCEPT, FILTER_REJECT, FILTER_SKIP) class FilterVisibilityController(object): """Wrapper around a DOMBuilderFilter which implements the checks to make the whatToShow filter attribute work.""" __slots__ = 'filter', def __init__(self, filter): self.filter = filter def startContainer(self, node): mask = self._nodetype_mask[node.nodeType] if self.filter.whatToShow & mask: val = self.filter.startContainer(node) if val == FILTER_INTERRUPT: raise ParseEscape if val not in _ALLOWED_FILTER_RETURNS: raise ValueError, \ "startContainer() returned illegal value: " + repr(val) return val else: return FILTER_ACCEPT def acceptNode(self, node): mask = self._nodetype_mask[node.nodeType] if self.filter.whatToShow & mask: val = self.filter.acceptNode(node) if val == FILTER_INTERRUPT: raise ParseEscape if val == FILTER_SKIP: # move all child nodes to the parent, and remove this node parent = node.parentNode for child in node.childNodes[:]: parent.appendChild(child) # node is handled by the caller return FILTER_REJECT if val not in _ALLOWED_FILTER_RETURNS: raise ValueError, \ "acceptNode() returned illegal value: " + repr(val) return val else: return FILTER_ACCEPT _nodetype_mask = { Node.ELEMENT_NODE: NodeFilter.SHOW_ELEMENT, Node.ATTRIBUTE_NODE: NodeFilter.SHOW_ATTRIBUTE, Node.TEXT_NODE: NodeFilter.SHOW_TEXT, Node.CDATA_SECTION_NODE: NodeFilter.SHOW_CDATA_SECTION, Node.ENTITY_REFERENCE_NODE: NodeFilter.SHOW_ENTITY_REFERENCE, Node.ENTITY_NODE: NodeFilter.SHOW_ENTITY, Node.PROCESSING_INSTRUCTION_NODE: NodeFilter.SHOW_PROCESSING_INSTRUCTION, Node.COMMENT_NODE: NodeFilter.SHOW_COMMENT, Node.DOCUMENT_NODE: NodeFilter.SHOW_DOCUMENT, Node.DOCUMENT_TYPE_NODE: NodeFilter.SHOW_DOCUMENT_TYPE, Node.DOCUMENT_FRAGMENT_NODE: NodeFilter.SHOW_DOCUMENT_FRAGMENT, Node.NOTATION_NODE: NodeFilter.SHOW_NOTATION, } class FilterCrutch(object): __slots__ = '_builder', '_level', '_old_start', '_old_end' def __init__(self, builder): self._level = 0 self._builder = builder parser = builder._parser self._old_start = parser.StartElementHandler self._old_end = parser.EndElementHandler parser.StartElementHandler = self.start_element_handler parser.EndElementHandler = self.end_element_handler class Rejecter(FilterCrutch): __slots__ = () def __init__(self, builder): FilterCrutch.__init__(self, builder) parser = builder._parser for name in ("ProcessingInstructionHandler", "CommentHandler", "CharacterDataHandler", "StartCdataSectionHandler", "EndCdataSectionHandler", "ExternalEntityRefHandler", ): setattr(parser, name, None) def start_element_handler(self, *args): self._level = self._level + 1 def end_element_handler(self, *args): if self._level == 0: # restore the old handlers parser = self._builder._parser self._builder.install(parser) parser.StartElementHandler = self._old_start parser.EndElementHandler = self._old_end else: self._level = self._level - 1 class Skipper(FilterCrutch): __slots__ = () def start_element_handler(self, *args): node = self._builder.curNode self._old_start(*args) if self._builder.curNode is not node: self._level = self._level + 1 def end_element_handler(self, *args): if self._level == 0: # We're popping back out of the node we're skipping, so we # shouldn't need to do anything but reset the handlers. self._builder._parser.StartElementHandler = self._old_start self._builder._parser.EndElementHandler = self._old_end self._builder = None else: self._level = self._level - 1 self._old_end(*args) # framework document used by the fragment builder. # Takes a string for the doctype, subset string, and namespace attrs string. _FRAGMENT_BUILDER_INTERNAL_SYSTEM_ID = \ "http://xml.python.org/entities/fragment-builder/internal" _FRAGMENT_BUILDER_TEMPLATE = ( '''\ <!DOCTYPE wrapper %%s [ <!ENTITY fragment-builder-internal SYSTEM "%s"> %%s ]> <wrapper %%s >&fragment-builder-internal;</wrapper>''' % _FRAGMENT_BUILDER_INTERNAL_SYSTEM_ID) class FragmentBuilder(ExpatBuilder): """Builder which constructs document fragments given XML source text and a context node. The context node is expected to provide information about the namespace declarations which are in scope at the start of the fragment. """ def __init__(self, context, options=None): if context.nodeType == DOCUMENT_NODE: self.originalDocument = context self.context = context else: self.originalDocument = context.ownerDocument self.context = context ExpatBuilder.__init__(self, options) def reset(self): ExpatBuilder.reset(self) self.fragment = None def parseFile(self, file): """Parse a document fragment from a file object, returning the fragment node.""" return self.parseString(file.read()) def parseString(self, string): """Parse a document fragment from a string, returning the fragment node.""" self._source = string parser = self.getParser() doctype = self.originalDocument.doctype ident = "" if doctype: subset = doctype.internalSubset or self._getDeclarations() if doctype.publicId: ident = ('PUBLIC "%s" "%s"' % (doctype.publicId, doctype.systemId)) elif doctype.systemId: ident = 'SYSTEM "%s"' % doctype.systemId else: subset = "" nsattrs = self._getNSattrs() # get ns decls from node's ancestors document = _FRAGMENT_BUILDER_TEMPLATE % (ident, subset, nsattrs) try: parser.Parse(document, 1) except: self.reset() raise fragment = self.fragment self.reset() ## self._parser = None return fragment def _getDeclarations(self): """Re-create the internal subset from the DocumentType node. This is only needed if we don't already have the internalSubset as a string. """ doctype = self.context.ownerDocument.doctype s = "" if doctype: for i in range(doctype.notations.length): notation = doctype.notations.item(i) if s: s = s + "\n " s = "%s<!NOTATION %s" % (s, notation.nodeName) if notation.publicId: s = '%s PUBLIC "%s"\n "%s">' \ % (s, notation.publicId, notation.systemId) else: s = '%s SYSTEM "%s">' % (s, notation.systemId) for i in range(doctype.entities.length): entity = doctype.entities.item(i) if s: s = s + "\n " s = "%s<!ENTITY %s" % (s, entity.nodeName) if entity.publicId: s = '%s PUBLIC "%s"\n "%s"' \ % (s, entity.publicId, entity.systemId) elif entity.systemId: s = '%s SYSTEM "%s"' % (s, entity.systemId) else: s = '%s "%s"' % (s, entity.firstChild.data) if entity.notationName: s = "%s NOTATION %s" % (s, entity.notationName) s = s + ">" return s def _getNSattrs(self): return "" def external_entity_ref_handler(self, context, base, systemId, publicId): if systemId == _FRAGMENT_BUILDER_INTERNAL_SYSTEM_ID: # this entref is the one that we made to put the subtree # in; all of our given input is parsed in here. old_document = self.document old_cur_node = self.curNode parser = self._parser.ExternalEntityParserCreate(context) # put the real document back, parse into the fragment to return self.document = self.originalDocument self.fragment = self.document.createDocumentFragment() self.curNode = self.fragment try: parser.Parse(self._source, 1) finally: self.curNode = old_cur_node self.document = old_document self._source = None return -1 else: return ExpatBuilder.external_entity_ref_handler( self, context, base, systemId, publicId) class Namespaces: """Mix-in class for builders; adds support for namespaces.""" def _initNamespaces(self): # list of (prefix, uri) ns declarations. Namespace attrs are # constructed from this and added to the element's attrs. self._ns_ordered_prefixes = [] def createParser(self): """Create a new namespace-handling parser.""" parser = expat.ParserCreate(namespace_separator=" ") parser.namespace_prefixes = True return parser def install(self, parser): """Insert the namespace-handlers onto the parser.""" ExpatBuilder.install(self, parser) if self._options.namespace_declarations: parser.StartNamespaceDeclHandler = ( self.start_namespace_decl_handler) def start_namespace_decl_handler(self, prefix, uri): """Push this namespace declaration on our storage.""" self._ns_ordered_prefixes.append((prefix, uri)) def start_element_handler(self, name, attributes): if ' ' in name: uri, localname, prefix, qname = _parse_ns_name(self, name) else: uri = EMPTY_NAMESPACE qname = name localname = None prefix = EMPTY_PREFIX node = minidom.Element(qname, uri, prefix, localname) node.ownerDocument = self.document _append_child(self.curNode, node) self.curNode = node if self._ns_ordered_prefixes: for prefix, uri in self._ns_ordered_prefixes: if prefix: a = minidom.Attr(_intern(self, 'xmlns:' + prefix), XMLNS_NAMESPACE, prefix, "xmlns") else: a = minidom.Attr("xmlns", XMLNS_NAMESPACE, "xmlns", EMPTY_PREFIX) d = a.childNodes[0].__dict__ d['data'] = d['nodeValue'] = uri d = a.__dict__ d['value'] = d['nodeValue'] = uri d['ownerDocument'] = self.document _set_attribute_node(node, a) del self._ns_ordered_prefixes[:] if attributes: _attrs = node._attrs _attrsNS = node._attrsNS for i in range(0, len(attributes), 2): aname = attributes[i] value = attributes[i+1] if ' ' in aname: uri, localname, prefix, qname = _parse_ns_name(self, aname) a = minidom.Attr(qname, uri, localname, prefix) _attrs[qname] = a _attrsNS[(uri, localname)] = a else: a = minidom.Attr(aname, EMPTY_NAMESPACE, aname, EMPTY_PREFIX) _attrs[aname] = a _attrsNS[(EMPTY_NAMESPACE, aname)] = a d = a.childNodes[0].__dict__ d['data'] = d['nodeValue'] = value d = a.__dict__ d['ownerDocument'] = self.document d['value'] = d['nodeValue'] = value d['ownerElement'] = node if __debug__: # This only adds some asserts to the original # end_element_handler(), so we only define this when -O is not # used. If changing one, be sure to check the other to see if # it needs to be changed as well. # def end_element_handler(self, name): curNode = self.curNode if ' ' in name: uri, localname, prefix, qname = _parse_ns_name(self, name) assert (curNode.namespaceURI == uri and curNode.localName == localname and curNode.prefix == prefix), \ "element stack messed up! (namespace)" else: assert curNode.nodeName == name, \ "element stack messed up - bad nodeName" assert curNode.namespaceURI == EMPTY_NAMESPACE, \ "element stack messed up - bad namespaceURI" self.curNode = curNode.parentNode self._finish_end_element(curNode) class ExpatBuilderNS(Namespaces, ExpatBuilder): """Document builder that supports namespaces.""" def reset(self): ExpatBuilder.reset(self) self._initNamespaces() class FragmentBuilderNS(Namespaces, FragmentBuilder): """Fragment builder that supports namespaces.""" def reset(self): FragmentBuilder.reset(self) self._initNamespaces() def _getNSattrs(self): """Return string of namespace attributes from this element and ancestors.""" # XXX This needs to be re-written to walk the ancestors of the # context to build up the namespace information from # declarations, elements, and attributes found in context. # Otherwise we have to store a bunch more data on the DOM # (though that *might* be more reliable -- not clear). attrs = "" context = self.context L = [] while context: if hasattr(context, '_ns_prefix_uri'): for prefix, uri in context._ns_prefix_uri.items(): # add every new NS decl from context to L and attrs string if prefix in L: continue L.append(prefix) if prefix: declname = "xmlns:" + prefix else: declname = "xmlns" if attrs: attrs = "%s\n %s='%s'" % (attrs, declname, uri) else: attrs = " %s='%s'" % (declname, uri) context = context.parentNode return attrs class ParseEscape(Exception): """Exception raised to short-circuit parsing in InternalSubsetExtractor.""" pass class InternalSubsetExtractor(ExpatBuilder): """XML processor which can rip out the internal document type subset.""" subset = None def getSubset(self): """Return the internal subset as a string.""" return self.subset def parseFile(self, file): try: ExpatBuilder.parseFile(self, file) except ParseEscape: pass def parseString(self, string): try: ExpatBuilder.parseString(self, string) except ParseEscape: pass def install(self, parser): parser.StartDoctypeDeclHandler = self.start_doctype_decl_handler parser.StartElementHandler = self.start_element_handler def start_doctype_decl_handler(self, name, publicId, systemId, has_internal_subset): if has_internal_subset: parser = self.getParser() self.subset = [] parser.DefaultHandler = self.subset.append parser.EndDoctypeDeclHandler = self.end_doctype_decl_handler else: raise ParseEscape() def end_doctype_decl_handler(self): s = ''.join(self.subset).replace('\r\n', '\n').replace('\r', '\n') self.subset = s raise ParseEscape() def start_element_handler(self, name, attrs): raise ParseEscape() def parse(file, namespaces=True): """Parse a document, returning the resulting Document node. 'file' may be either a file name or an open file object. """ if namespaces: builder = ExpatBuilderNS() else: builder = ExpatBuilder() if isinstance(file, StringTypes): fp = open(file, 'rb') try: result = builder.parseFile(fp) finally: fp.close() else: result = builder.parseFile(file) return result def parseString(string, namespaces=True): """Parse a document from a string, returning the resulting Document node. """ if namespaces: builder = ExpatBuilderNS() else: builder = ExpatBuilder() return builder.parseString(string) def parseFragment(file, context, namespaces=True): """Parse a fragment of a document, given the context from which it was originally extracted. context should be the parent of the node(s) which are in the fragment. 'file' may be either a file name or an open file object. """ if namespaces: builder = FragmentBuilderNS(context) else: builder = FragmentBuilder(context) if isinstance(file, StringTypes): fp = open(file, 'rb') try: result = builder.parseFile(fp) finally: fp.close() else: result = builder.parseFile(file) return result def parseFragmentString(string, context, namespaces=True): """Parse a fragment of a document from a string, given the context from which it was originally extracted. context should be the parent of the node(s) which are in the fragment. """ if namespaces: builder = FragmentBuilderNS(context) else: builder = FragmentBuilder(context) return builder.parseString(string) def makeBuilder(options): """Create a builder based on an Options object.""" if options.namespaces: return ExpatBuilderNS(options) else: return ExpatBuilder(options)
