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- # A parser for SGML, using the derived class as static DTD.
-
- # XXX This only supports those SGML features used by HTML.
-
- # XXX There should be a way to distinguish between PCDATA (parsed
- # character data -- the normal case), RCDATA (replaceable character
- # data -- only char and entity references and end tags are special)
- # and CDATA (character data -- only end tags are special).
-
-
- import re
- import string
-
-
- # Regular expressions used for parsing
-
- interesting = re.compile('[&<]')
- incomplete = re.compile('&([a-zA-Z][a-zA-Z0-9]*|#[0-9]*)?|'
- '<([a-zA-Z][^<>]*|'
- '/([a-zA-Z][^<>]*)?|'
- '![^<>]*)?')
-
- entityref = re.compile('&([a-zA-Z][-.a-zA-Z0-9]*)[^a-zA-Z0-9]')
- charref = re.compile('([0-9]+)[^0-9]')
-
- starttagopen = re.compile('<[>a-zA-Z]')
- shorttagopen = re.compile('<[a-zA-Z][-.a-zA-Z0-9]*/')
- shorttag = re.compile('<([a-zA-Z][-.a-zA-Z0-9]*)/([^/]*)/')
- piopen = re.compile('<\?')
- piclose = re.compile('>')
- endtagopen = re.compile('</[<>a-zA-Z]')
- endbracket = re.compile('[<>]')
- special = re.compile('<![^<>]*>')
- commentopen = re.compile('<!--')
- commentclose = re.compile('--[%s]*>' % string.whitespace)
- tagfind = re.compile('[a-zA-Z][-.a-zA-Z0-9]*')
- attrfind = re.compile(
- '[%s]*([a-zA-Z_][-.a-zA-Z_0-9]*)' % string.whitespace
- + ('([%s]*=[%s]*' % (string.whitespace, string.whitespace))
- + r'(\'[^\']*\'|"[^"]*"|[-a-zA-Z0-9./:+*%?!\(\)_#=~]*))?')
-
-
- # SGML parser base class -- find tags and call handler functions.
- # Usage: p = SGMLParser(); 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 SGMLParser:
-
- # 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
-
- # 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)
-
- # 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:
- self.handle_data(rawdata[i:n])
- i = n
- break
- match = interesting.search(rawdata, i)
- if match: j = match.start(0)
- else: j = n
- if i < j: self.handle_data(rawdata[i:j])
- i = j
- if i == n: break
- if rawdata[i] == '<':
- if starttagopen.match(rawdata, i):
- if self.literal:
- self.handle_data(rawdata[i])
- i = i+1
- continue
- k = self.parse_starttag(i)
- if k < 0: break
- i = k
- continue
- if endtagopen.match(rawdata, i):
- k = self.parse_endtag(i)
- if k < 0: break
- i = k
- self.literal = 0
- continue
- if commentopen.match(rawdata, i):
- if self.literal:
- self.handle_data(rawdata[i])
- i = i+1
- continue
- k = self.parse_comment(i)
- if k < 0: break
- i = i+k
- continue
- if piopen.match(rawdata, i):
- if self.literal:
- self.handle_data(rawdata[i])
- i = i+1
- continue
- k = self.parse_pi(i)
- if k < 0: break
- i = i+k
- continue
- match = special.match(rawdata, i)
- if match:
- if self.literal:
- self.handle_data(rawdata[i])
- i = i+1
- continue
- i = match.end(0)
- continue
- elif rawdata[i] == '&':
- match = charref.match(rawdata, i)
- if match:
- name = match.group(1)
- self.handle_charref(name)
- i = match.end(0)
- if rawdata[i-1] != ';': i = i-1
- continue
- match = entityref.match(rawdata, i)
- if match:
- name = match.group(1)
- self.handle_entityref(name)
- i = match.end(0)
- if rawdata[i-1] != ';': i = i-1
- continue
- else:
- raise RuntimeError, 'neither < nor & ??'
- # We get here only if incomplete matches but
- # nothing else
- match = incomplete.match(rawdata, i)
- if not match:
- self.handle_data(rawdata[i])
- i = i+1
- continue
- j = match.end(0)
- if j == n:
- break # Really incomplete
- self.handle_data(rawdata[i:j])
- i = j
- # end while
- if end and i < n:
- self.handle_data(rawdata[i: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'
- match = commentclose.search(rawdata, i+4)
- if not match:
- return -1
- j = match.start(0)
- self.handle_comment(rawdata[i+4: j])
- j = match.end(0)
- return j-i
-
- # Internal -- parse processing instr, return length or -1 if not terminated
- def parse_pi(self, i):
- rawdata = self.rawdata
- if rawdata[i:i+2] <> '<?':
- raise RuntimeError, 'unexpected call to handle_pi'
- match = piclose.search(rawdata, i+2)
- if not match:
- return -1
- j = match.start(0)
- self.handle_pi(rawdata[i+2: j])
- j = match.end(0)
- return j-i
-
- # Internal -- handle starttag, return length or -1 if not terminated
- def parse_starttag(self, i):
- rawdata = self.rawdata
- if shorttagopen.match(rawdata, i):
- # SGML shorthand: <tag/data/ == <tag>data</tag>
- # XXX Can data contain &... (entity or char refs)?
- # XXX Can data contain < or > (tag characters)?
- # XXX Can there be whitespace before the first /?
- match = shorttag.match(rawdata, i)
- if not match:
- return -1
- tag, data = match.group(1, 2)
- tag = string.lower(tag)
- self.finish_shorttag(tag, data)
- k = match.end(0)
- return k
- # XXX The following should skip matching quotes (' or ")
- match = endbracket.search(rawdata, i+1)
- if not match:
- return -1
- j = match.start(0)
- # Now parse the data between i+1 and j into a tag and attrs
- attrs = []
- if rawdata[i:i+2] == '<>':
- # SGML shorthand: <> == <last open tag seen>
- k = j
- tag = self.lasttag
- else:
- match = tagfind.match(rawdata, i+1)
- if not match:
- raise RuntimeError, 'unexpected call to parse_starttag'
- k = match.end(0)
- tag = string.lower(rawdata[i+1:k])
- self.lasttag = tag
- while k < j:
- match = attrfind.match(rawdata, k)
- if not match: break
- attrname, rest, attrvalue = match.group(1, 2, 3)
- if not rest:
- attrvalue = attrname
- elif attrvalue[:1] == '\'' == attrvalue[-1:] or \
- attrvalue[:1] == '"' == attrvalue[-1:]:
- attrvalue = attrvalue[1:-1]
- attrs.append((string.lower(attrname), attrvalue))
- k = match.end(0)
- if rawdata[j] == '>':
- j = j+1
- self.finish_starttag(tag, attrs)
- return j
-
- # Internal -- parse endtag
- def parse_endtag(self, i):
- rawdata = self.rawdata
- match = endbracket.search(rawdata, i+1)
- if not match:
- return -1
- j = match.start(0)
- tag = string.lower(string.strip(rawdata[i+2:j]))
- if rawdata[j] == '>':
- j = j+1
- self.finish_endtag(tag)
- return j
-
- # Internal -- finish parsing of <tag/data/ (same as <tag>data</tag>)
- def finish_shorttag(self, tag, data):
- self.finish_starttag(tag, [])
- self.handle_data(data)
- self.finish_endtag(tag)
-
- # Internal -- finish processing of start tag
- # Return -1 for unknown tag, 0 for open-only tag, 1 for balanced tag
- def finish_starttag(self, tag, attrs):
- try:
- method = getattr(self, 'start_' + tag)
- except AttributeError:
- try:
- method = getattr(self, 'do_' + tag)
- except AttributeError:
- self.unknown_starttag(tag, attrs)
- return -1
- else:
- self.handle_starttag(tag, method, attrs)
- return 0
- else:
- self.stack.append(tag)
- 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)
- else:
- self.report_unbalanced(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 -- report an unbalanced </...> tag.
- def report_unbalanced(self, tag):
- if self.verbose:
- print '*** Unbalanced </' + tag + '>'
- print '*** Stack:', self.stack
-
- # Example -- handle character reference, no need to override
- def handle_charref(self, name):
- try:
- 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 comment, could be overridden
- def handle_comment(self, data):
- pass
-
- # Example -- handle processing instruction, could be overridden
- def handle_pi(self, data):
- pass
-
- # 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 TestSGMLParser(SGMLParser):
-
- def __init__(self, verbose=0):
- self.testdata = ""
- SGMLParser.__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_comment(self, data):
- self.flush()
- r = `data`
- if len(r) > 68:
- r = r[:32] + '...' + r[-32:]
- print 'comment:', r
-
- 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):
- SGMLParser.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 = SGMLParser
- else:
- klass = TestSGMLParser
-
- if args:
- file = args[0]
- else:
- file = 'test.html'
-
- 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()
-