"""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).  RCDATA is# not supported at all.  import markupbaseimport re __all__ = ["SGMLParser", "SGMLParseError"] # 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]*)/([^/]*)/')piclose = re.compile('>')endbracket = re.compile('[<>]')tagfind = re.compile('[a-zA-Z][-_.a-zA-Z0-9]*')attrfind = re.compile(    r'\s*([a-zA-Z_][-:.a-zA-Z_0-9]*)(\s*=\s*'    r'(\'[^\']*\'|"[^"]*"|[][\-a-zA-Z0-9./,:;+*%?!&$\(\)_#=~\'"@]*))?')  class SGMLParseError(RuntimeError):    """Exception raised for all parse errors."""    pass  # 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(markupbase.ParserBase):    # Definition of entities -- derived classes may override    entity_or_charref = re.compile('&(?:'      '([a-zA-Z][-.a-zA-Z0-9]*)|#([0-9]+)'      ')(;?)')     def __init__(self, verbose=0):        """Initialize and reset this instance."""        self.verbose = verbose        self.reset()     def reset(self):        """Reset this instance. Loses all unprocessed data."""        self.__starttag_text = None        self.rawdata = ''        self.stack = []        self.lasttag = '???'        self.nomoretags = 0        self.literal = 0        markupbase.ParserBase.reset(self)     def setnomoretags(self):        """Enter literal mode (CDATA) till EOF.         Intended for derived classes only.        """        self.nomoretags = self.literal = 1     def setliteral(self, *args):        """Enter literal mode (CDATA).         Intended for derived classes only.        """        self.literal = 1     def feed(self, data):        """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().)        """         self.rawdata = self.rawdata + data        self.goahead(0)     def close(self):        """Handle the remaining data."""        self.goahead(1)     def error(self, message):        raise SGMLParseError(message)     # 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()            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 rawdata.startswith("</", i):                    k = self.parse_endtag(i)                    if k < 0: break                    i = k                    self.literal = 0                    continue                if self.literal:                    if n > (i + 1):                        self.handle_data("<")                        i = i+1                    else:                        # incomplete                        break                    continue                if rawdata.startswith("<!--", i):                        # Strictly speaking, a comment is --.*--                        # within a declaration tag <!...>.                        # This should be removed,                        # and comments handled only in parse_declaration.                    k = self.parse_comment(i)                    if k < 0: break                    i = k                    continue                if rawdata.startswith("<?", i):                    k = self.parse_pi(i)                    if k < 0: break                    i = i+k                    continue                if rawdata.startswith("<!", i):                    # This is some sort of declaration; in "HTML as                    # deployed," this should only be the document type                    # declaration ("<!DOCTYPE html...>").                    k = self.parse_declaration(i)                    if k < 0: break                    i = k                    continue            elif rawdata[i] == '&':                if self.literal:                    self.handle_data(rawdata[i])                    i = i+1                    continue                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:                self.error('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     # Extensions for the DOCTYPE scanner:    _decl_otherchars = '='     # Internal -- parse processing instr, return length or -1 if not terminated    def parse_pi(self, i):        rawdata = self.rawdata        if rawdata[i:i+2] != '<?':            self.error('unexpected call to parse_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     def get_starttag_text(self):        return self.__starttag_text     # Internal -- handle starttag, return length or -1 if not terminated    def parse_starttag(self, i):        self.__starttag_text = None        start_pos = 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)            self.__starttag_text = '<%s/' % tag            tag = tag.lower()            k = match.end(0)            self.finish_shorttag(tag, data)            self.__starttag_text = rawdata[start_pos:match.end(1) + 1]            return k        # XXX The following should skip matching quotes (' or ")        # As a shortcut way to exit, this isn't so bad, but shouldn't        # be used to locate the actual end of the start tag since the        # < or > characters may be embedded in an attribute value.        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:                self.error('unexpected call to parse_starttag')            k = match.end(0)            tag = rawdata[i+1:k].lower()            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            else:                if (attrvalue[:1] == "'" == attrvalue[-1:] or                    attrvalue[:1] == '"' == attrvalue[-1:]):                    # strip quotes                    attrvalue = attrvalue[1:-1]                attrvalue = self.entity_or_charref.sub(                    self._convert_ref, attrvalue)            attrs.append((attrname.lower(), attrvalue))            k = match.end(0)        if rawdata[j] == '>':            j = j+1        self.__starttag_text = rawdata[start_pos:j]        self.finish_starttag(tag, attrs)        return j     # Internal -- convert entity or character reference    def _convert_ref(self, match):        if match.group(2):            return self.convert_charref(match.group(2)) or \                '&#%s%s' % match.groups()[1:]        elif match.group(3):            return self.convert_entityref(match.group(1)) or \                '&%s;' % match.group(1)        else:            return '&%s' % match.group(1)     # 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 = rawdata[i+2:j].strip().lower()        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     def convert_charref(self, name):        """Convert character reference, may be overridden."""        try:            n = int(name)        except ValueError:            return        if not 0 <= n <= 255:            return        return self.convert_codepoint(n)     def convert_codepoint(self, codepoint):        return chr(codepoint)     def handle_charref(self, name):        """Handle character reference, no need to override."""        replacement = self.convert_charref(name)        if replacement is None:            self.unknown_charref(name)        else:            self.handle_data(replacement)     # Definition of entities -- derived classes may override    entitydefs = \            {'lt': '<', 'gt': '>', 'amp': '&', 'quot': '"', 'apos': '\''}     def convert_entityref(self, name):        """Convert entity references.         As an alternative to overriding this method; one can tailor the        results by setting up the self.entitydefs mapping appropriately.        """        table = self.entitydefs        if name in table:            return table[name]        else:            return     def handle_entityref(self, name):        """Handle entity references, no need to override."""        replacement = self.convert_entityref(name)        if replacement is None:            self.unknown_entityref(name)        else:            self.handle_data(self.convert_entityref(name))     # 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 declaration, could be overridden    def handle_decl(self, decl):        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(repr(self.testdata)) >= 70:            self.flush()     def flush(self):        data = self.testdata        if data:            self.testdata = ""            print 'data:', repr(data)     def handle_comment(self, data):        self.flush()        r = repr(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 + ';'

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