| """A parser for SGML, using the derived class as a 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 arbitrary |
| # 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() |