Sjoerd Mullender's xml parser (based on sgmllib, somewhat).

Lib/xmllib.py

+# A parser for XML, using the derived class as static DTD.
+# Author: Sjoerd Mullender
+
+import re
+import string
+
+
+# Regular expressions used for parsing
+
+_S = '[ \t\r\n]+'
+_opS = '[ \t\r\n]*'
+_Name = '[a-zA-Z_:][-a-zA-Z0-9._:]*'
+interesting = re.compile('[&<]')
+incomplete = re.compile('&(' + _Name + '|#[0-9]*|#x[0-9a-fA-F]*)?|'
+			   '<([a-zA-Z_:][^<>]*|'
+			      '/([a-zA-Z_:][^<>]*)?|'
+			      '![^<>]*|'
+			      '\?[^<>]*)?')
+
+ref = re.compile('&(' + _Name + '|#[0-9]+|#x[0-9a-fA-F]+);?')
+entityref = re.compile('&(?P<name>' + _Name + ')[^-a-zA-Z0-9._:]')
+charref = re.compile('&#(?P<char>[0-9]+[^0-9]|x[0-9a-fA-F]+[^0-9a-fA-F])')
+space = re.compile(_S)
+newline = re.compile('\n')
+
+starttagopen = re.compile('<' + _Name)
+endtagopen = re.compile('</')
+starttagend = re.compile(_opS + '(?P<slash>/?)>')
+endbracket = re.compile('>')
+tagfind = re.compile(_Name)
+cdataopen = re.compile('<!\[CDATA\[')
+cdataclose = re.compile('\]\]>')
+special = re.compile('<!(?P<special>[^<>]*)>')
+procopen = re.compile('<\?(?P<proc>' + _Name + ')' + _S)
+procclose = re.compile('\?>')
+commentopen = re.compile('<!--')
+commentclose = re.compile('-->')
+doubledash = re.compile('--')
+attrfind = re.compile(
+    _S + '(?P<name>' + _Name + ')'
+    '(' + _opS + '=' + _opS +
+    '(?P<value>\'[^\']*\'|"[^"]*"|[-a-zA-Z0-9.:+*%?!()_#=~]+))')
+
+
+# XML parser base class -- find tags and call handler functions.
+# Usage: p = XMLParser(); p.feed(data); ...; p.close().
+# The dtd is defined by deriving a class which defines methods
+# with special names to handle tags: start_foo and end_foo to handle
+# <foo> and </foo>, respectively, or do_foo to handle <foo> by itself.
+# (Tags are converted to lower case for this purpose.)  The data
+# between tags is passed to the parser by calling self.handle_data()
+# with some data as argument (the data may be split up in arbutrary
+# chunks).  Entity references are passed by calling
+# self.handle_entityref() with the entity reference as argument.
+
+class XMLParser:
+
+    # Interface -- initialize and reset this instance
+    def __init__(self, verbose=0):
+	self.verbose = verbose
+	self.reset()
+
+    # Interface -- reset this instance.  Loses all unprocessed data
+    def reset(self):
+	self.rawdata = ''
+	self.stack = []
+	self.lasttag = '???'
+	self.nomoretags = 0
+	self.literal = 0
+	self.lineno = 1
+
+    # For derived classes only -- enter literal mode (CDATA) till EOF
+    def setnomoretags(self):
+	self.nomoretags = self.literal = 1
+
+    # For derived classes only -- enter literal mode (CDATA)
+    def setliteral(self, *args):
+	self.literal = 1
+
+    # Interface -- feed some data to the parser.  Call this as
+    # often as you want, with as little or as much text as you
+    # want (may include '\n').  (This just saves the text, all the
+    # processing is done by goahead().)
+    def feed(self, data):
+	self.rawdata = self.rawdata + data
+	self.goahead(0)
+
+    # Interface -- handle the remaining data
+    def close(self):
+	self.goahead(1)
+
+    # Interface -- translate references
+    def translate_references(self, data):
+	newdata = []
+	i = 0
+	while 1:
+	    res = ref.search(data, i)
+	    if res is None:
+		newdata.append(data[i:])
+		return string.join(newdata, '')
+	    if data[res.end(0) - 1] != ';':
+		self.syntax_error(self.lineno,
+				  '; missing after entity/char reference')
+	    newdata.append(data[i:res.start(0)])
+	    str = res.group(1)
+	    if str[0] == '#':
+		if str[1] == 'x':
+		    newdata.append(chr(string.atoi(str[2:], 16)))
+		else:
+		    newdata.append(chr(string.atoi(str[1:])))
+	    else:
+		try:
+		    newdata.append(self.entitydefs[str])
+		except KeyError:
+		    # can't do it, so keep the entity ref in
+		    newdata.append('&' + str + ';')
+	    i = res.end(0)
+
+    # Internal -- handle data as far as reasonable.  May leave state
+    # and data to be processed by a subsequent call.  If 'end' is
+    # true, force handling all data as if followed by EOF marker.
+    def goahead(self, end):
+	rawdata = self.rawdata
+	i = 0
+	n = len(rawdata)
+	while i < n:
+	    if self.nomoretags:
+		data = rawdata[i:n]
+		self.handle_data(data)
+		self.lineno = self.lineno + string.count(data, '\n')
+		i = n
+		break
+	    res = interesting.search(rawdata, i)
+	    if res:
+		    j = res.start(0)
+	    else:
+		    j = n
+	    if i < j:
+		data = rawdata[i:j]
+		self.handle_data(data)
+		self.lineno = self.lineno + string.count(data, '\n')
+	    i = j
+	    if i == n: break
+	    if rawdata[i] == '<':
+		if starttagopen.match(rawdata, i):
+		    if self.literal:
+			data = rawdata[i]
+			self.handle_data(data)
+			self.lineno = self.lineno + string.count(data, '\n')
+			i = i+1
+			continue
+		    k = self.parse_starttag(i)
+		    if k < 0: break
+		    self.lineno = self.lineno + string.count(rawdata[i:k], '\n')
+		    i = k
+		    continue
+		if endtagopen.match(rawdata, i):
+		    k = self.parse_endtag(i)
+		    if k < 0: break
+		    self.lineno = self.lineno + string.count(rawdata[i:k], '\n')
+		    i =  k
+		    self.literal = 0
+		    continue
+		if commentopen.match(rawdata, i):
+		    if self.literal:
+			data = rawdata[i]
+			self.handle_data(data)
+			self.lineno = self.lineno + string.count(data, '\n')
+			i = i+1
+			continue
+		    k = self.parse_comment(i)
+		    if k < 0: break
+		    self.lineno = self.lineno + string.count(rawdata[i:k], '\n')
+		    i = k
+		    continue
+		if cdataopen.match(rawdata, i):
+		    k = self.parse_cdata(i)
+		    if k < 0: break
+		    self.lineno = self.lineno + string.count(rawdata[i:i], '\n')
+		    i = k
+		    continue
+		res = procopen.match(rawdata, i)
+		if res:
+		    k = self.parse_proc(i, res)
+		    if k < 0: break
+		    self.lineno = self.lineno + string.count(rawdata[i:k], '\n')
+		    i = k
+		    continue
+		res = special.match(rawdata, i)
+		if res:
+		    if self.literal:
+			data = rawdata[i]
+			self.handle_data(data)
+			self.lineno = self.lineno + string.count(data, '\n')
+			i = i+1
+			continue
+		    self.handle_special(res.group('special'))
+		    self.lineno = self.lineno + string.count(res.group(0), '\n')
+		    i = res.end(0)
+		    continue
+	    elif rawdata[i] == '&':
+		res = charref.match(rawdata, i)
+		if res is not None:
+		    i = res.end(0)
+		    if rawdata[i-1] != ';':
+			self.syntax_error(self.lineno, '; missing in charref')
+			i = i-1
+		    self.handle_charref(res.group('char')[:-1])
+		    self.lineno = self.lineno + string.count(res.group(0), '\n')
+		    continue
+		res = entityref.match(rawdata, i)
+		if res is not None:
+		    i = res.end(0)
+		    if rawdata[i-1] != ';':
+			self.syntax_error(self.lineno, '; missing in entityref')
+			i = i-1
+		    self.handle_entityref(res.group('name'))
+		    self.lineno = self.lineno + string.count(res.group(0), '\n')
+		    continue
+	    else:
+		raise RuntimeError, 'neither < nor & ??'
+	    # We get here only if incomplete matches but
+	    # nothing else
+	    res = incomplete.match(rawdata, i)
+	    if not res:
+		data = rawdata[i]
+		self.handle_data(data)
+		self.lineno = self.lineno + string.count(data, '\n')
+		i = i+1
+		continue
+	    j = res.end(0)
+	    if j == n:
+		break # Really incomplete
+	    self.syntax_error(self.lineno, 'bogus < or &')
+	    data = res.group(0)
+	    self.handle_data(data)
+	    self.lineno = self.lineno + string.count(data, '\n')
+	    i = j
+	# end while
+	if end and i < n:
+	    data = rawdata[i:n]
+	    self.handle_data(data)
+	    self.lineno = self.lineno + string.count(data, '\n')
+	    i = n
+	self.rawdata = rawdata[i:]
+	# XXX if end: check for empty stack
+
+    # Internal -- parse comment, return length or -1 if not terminated
+    def parse_comment(self, i):
+	rawdata = self.rawdata
+	if rawdata[i:i+4] <> '<!--':
+	    raise RuntimeError, 'unexpected call to handle_comment'
+	res = commentclose.search(rawdata, i+4)
+	if not res:
+	    return -1
+	# doubledash search will succeed because it's a subset of commentclose
+	if doubledash.search(rawdata, i+4).start(0) < res.start(0):
+	    self.syntax_error(self.lineno, "`--' inside comment")
+	self.handle_comment(rawdata[i+4: res.start(0)])
+	return res.end(0)
+
+    # Internal -- handle CDATA tag, return lenth or -1 if not terminated
+    def parse_cdata(self, i):
+	rawdata = self.rawdata
+	if rawdata[i:i+9] <> '<![CDATA[':
+	    raise RuntimeError, 'unexpected call to handle_cdata'
+	res = cdataclose.search(rawdata, i+9)
+	if not res:
+	    return -1
+	self.handle_cdata(rawdata[i+9:res.start(0)])
+	return res.end(0)
+
+    def parse_proc(self, i, res):
+	rawdata = self.rawdata
+	if not res:
+	    raise RuntimeError, 'unexpected call to parse_proc'
+	name = res.group('proc')
+	res = procclose.search(rawdata, res.end(0))
+	if not res:
+	    return -1
+	self.handle_proc(name, rawdata[res.pos:res.start(0)])
+	return res.end(0)
+
+    # Internal -- handle starttag, return length or -1 if not terminated
+    def parse_starttag(self, i):
+	rawdata = self.rawdata
+	# i points to start of tag
+	end = endbracket.search(rawdata, i+1)
+	if not end:
+	    return -1
+	j = end.start(0)
+	# Now parse the data between i+1 and j into a tag and attrs
+	attrdict = {}
+	res = tagfind.match(rawdata, i+1)
+	if not res:
+	    raise RuntimeError, 'unexpected call to parse_starttag'
+	k = res.end(0)
+	tag = res.group(0)
+	if hasattr(self, tag + '_attributes'):
+	    attrlist = getattr(self, tag + '_attributes')
+	else:
+	    attrlist = None
+	self.lasttag = tag
+	while k < j:
+	    res = attrfind.match(rawdata, k)
+	    if not res: break
+	    attrname, attrvalue = res.group('name', 'value')
+	    if attrvalue is None:
+		self.syntax_error(self.lineno, 'no attribute value specified')
+		attrvalue = attrname
+	    elif attrvalue[:1] == "'" == attrvalue[-1:] or \
+		 attrvalue[:1] == '"' == attrvalue[-1:]:
+		attrvalue = attrvalue[1:-1]
+	    else:
+		self.syntax_error(self.lineno, 'attribute value not quoted')
+	    # XXXX are attribute names case sensitive?
+	    attrname = string.lower(attrname)
+	    if attrlist is not None and attrname not in attrlist:
+		self.syntax_error(self.lineno,
+				  'unknown attribute %s of element %s' %
+				  (attrname, tag))
+	    if attrdict.has_key(attrname):
+		self.syntax_error(self.lineno, 'attribute specified twice')
+	    attrdict[attrname] = self.translate_references(attrvalue)
+	    k = res.end(0)
+	res = starttagend.match(rawdata, k)
+	if not res:
+	    self.syntax_error(self.lineno, 'garbage in start tag')
+	self.finish_starttag(tag, attrdict)
+	if res and res.group('slash') == '/':
+	    self.finish_endtag(tag)
+	return end.end(0)
+
+    # Internal -- parse endtag
+    def parse_endtag(self, i):
+	rawdata = self.rawdata
+	end = endbracket.search(rawdata, i+1)
+	if not end:
+	    return -1
+	res = tagfind.match(rawdata, i+2)
+	if not res:
+	    self.syntax_error(self.lineno, 'no name specified in end tag')
+	    tag = ''
+	    k = i+2
+	else:
+	    tag = res.group(0)
+	    k = res.end(0)
+	if k != end.start(0):
+	    # check that there is only white space at end of tag
+	    res = space.match(rawdata, k)
+	    if res is None or res.end(0) != end.start(0):
+		self.syntax_error(self.lineno, 'garbage in end tag')
+	self.finish_endtag(tag)
+	return end.end(0)
+
+    # Internal -- finish processing of start tag
+    # Return -1 for unknown tag, 1 for balanced tag
+    def finish_starttag(self, tag, attrs):
+	self.stack.append(tag)
+	try:
+	    method = getattr(self, 'start_' + tag)
+	except AttributeError:
+	    self.unknown_starttag(tag, attrs)
+	    return -1
+	else:
+	    self.handle_starttag(tag, method, attrs)
+	    return 1
+
+    # Internal -- finish processing of end tag
+    def finish_endtag(self, tag):
+	if not tag:
+	    found = len(self.stack) - 1
+	    if found < 0:
+		self.unknown_endtag(tag)
+		return
+	else:
+	    if tag not in self.stack:
+		try:
+		    method = getattr(self, 'end_' + tag)
+		except AttributeError:
+		    self.unknown_endtag(tag)
+		return
+	    found = len(self.stack)
+	    for i in range(found):
+		if self.stack[i] == tag: found = i
+	while len(self.stack) > found:
+	    tag = self.stack[-1]
+	    try:
+		method = getattr(self, 'end_' + tag)
+	    except AttributeError:
+		method = None
+	    if method:
+		self.handle_endtag(tag, method)
+	    else:
+		self.unknown_endtag(tag)
+	    del self.stack[-1]
+
+    # Overridable -- handle start tag
+    def handle_starttag(self, tag, method, attrs):
+	method(attrs)
+
+    # Overridable -- handle end tag
+    def handle_endtag(self, tag, method):
+	method()
+
+    # Example -- handle character reference, no need to override
+    def handle_charref(self, name):
+	try:
+	    if name[0] == 'x':
+		n = string.atoi(name[1:], 16)
+	    else:
+		n = string.atoi(name)
+	except string.atoi_error:
+	    self.unknown_charref(name)
+	    return
+	if not 0 <= n <= 255:
+	    self.unknown_charref(name)
+	    return
+	self.handle_data(chr(n))
+
+    # Definition of entities -- derived classes may override
+    entitydefs = \
+	    {'lt': '<', 'gt': '>', 'amp': '&', 'quot': '"', 'apos': '\''}
+
+    # Example -- handle entity reference, no need to override
+    def handle_entityref(self, name):
+	table = self.entitydefs
+	if table.has_key(name):
+	    self.handle_data(table[name])
+	else:
+	    self.unknown_entityref(name)
+	    return
+
+    # Example -- handle data, should be overridden
+    def handle_data(self, data):
+	pass
+
+    # Example -- handle cdata, could be overridden
+    def handle_cdata(self, data):
+	pass
+
+    # Example -- handle comment, could be overridden
+    def handle_comment(self, data):
+	pass
+
+    # Example -- handle processing instructions, could be overridden
+    def handle_proc(self, name, data):
+	pass
+
+    # Example -- handle special instructions, could be overridden
+    def handle_special(self, data):
+	pass
+
+    # Example -- handle relatively harmless syntax errors, could be overridden
+    def syntax_error(self, lineno, message):
+	raise RuntimeError, 'Syntax error at line %d: %s' % (lineno, message)
+
+    # To be overridden -- handlers for unknown objects
+    def unknown_starttag(self, tag, attrs): pass
+    def unknown_endtag(self, tag): pass
+    def unknown_charref(self, ref): pass
+    def unknown_entityref(self, ref): pass
+
+
+class TestXMLParser(XMLParser):
+
+    def __init__(self, verbose=0):
+	self.testdata = ""
+	XMLParser.__init__(self, verbose)
+
+    def handle_data(self, data):
+	self.testdata = self.testdata + data
+	if len(`self.testdata`) >= 70:
+	    self.flush()
+
+    def flush(self):
+	data = self.testdata
+	if data:
+	    self.testdata = ""
+	    print 'data:', `data`
+
+    def handle_cdata(self, data):
+	self.flush()
+	print 'cdata:', `data`
+
+    def handle_proc(self, name, data):
+	self.flush()
+	print 'processing:',name,`data`
+
+    def handle_special(self, data):
+	self.flush()
+	print 'special:',`data`
+
+    def handle_comment(self, data):
+	self.flush()
+	r = `data`
+	if len(r) > 68:
+	    r = r[:32] + '...' + r[-32:]
+	print 'comment:', r
+
+    def syntax_error(self, lineno, message):
+	print 'error at line %d:' % lineno, message
+
+    def unknown_starttag(self, tag, attrs):
+	self.flush()
+	if not attrs:
+	    print 'start tag: <' + tag + '>'
+	else:
+	    print 'start tag: <' + tag,
+	    for name, value in attrs:
+		print name + '=' + '"' + value + '"',
+	    print '>'
+
+    def unknown_endtag(self, tag):
+	self.flush()
+	print 'end tag: </' + tag + '>'
+
+    def unknown_entityref(self, ref):
+	self.flush()
+	print '*** unknown entity ref: &' + ref + ';'
+
+    def unknown_charref(self, ref):
+	self.flush()
+	print '*** unknown char ref: &#' + ref + ';'
+
+    def close(self):
+	XMLParser.close(self)
+	self.flush()
+
+def test(args = None):
+    import sys
+
+    if not args:
+	args = sys.argv[1:]
+
+    if args and args[0] == '-s':
+	args = args[1:]
+	klass = XMLParser
+    else:
+	klass = TestXMLParser
+
+    if args:
+	file = args[0]
+    else:
+	file = 'test.xml'
+
+    if file == '-':
+	f = sys.stdin
+    else:
+	try:
+	    f = open(file, 'r')
+	except IOError, msg:
+	    print file, ":", msg
+	    sys.exit(1)
+
+    data = f.read()
+    if f is not sys.stdin:
+	f.close()
+
+    x = klass()
+    for c in data:
+	x.feed(c)
+    x.close()
+
+
+if __name__ == '__main__':
+    test()
+