# From Dive Into Python from sgmllib import SGMLParser import htmlentitydefs class BaseHTMLProcessor(SGMLParser): def reset(self): # extend (called by SGMLParser.__init__) self.pieces = [] SGMLParser.reset(self) def unknown_starttag(self, tag, attrs): # called for each start tag # attrs is a list of (attr, value) tuples # e.g. for 
, tag="pre", attrs=[("class", "screen")]
        # Ideally we would like to reconstruct original tag and attributes, but
        # we may end up quoting attribute values that weren't quoted in the source
        # document, or we may change the type of quotes around the attribute value
        # (single to double quotes).
        # Note that improperly embedded non-HTML code (like client-side Javascript)
        # may be parsed incorrectly by the ancestor, causing runtime script errors.
        # All non-HTML code must be enclosed in HTML comment tags ()
        # to ensure that it will pass through this parser unaltered (in handle_comment).
        strattrs = "".join([' %s="%s"' % (key, value) for key, value in attrs])
        self.pieces.append("<%(tag)s%(strattrs)s>" % locals())

    def unknown_endtag(self, tag):         
        # called for each end tag, e.g. for
, tag will be "pre" # Reconstruct the original end tag. self.pieces.append("" % locals()) def handle_charref(self, ref): # called for each character reference, e.g. for " ", ref will be "160" # Reconstruct the original character reference. self.pieces.append("&#%(ref)s;" % locals()) def handle_entityref(self, ref): # called for each entity reference, e.g. for "©", ref will be "copy" # Reconstruct the original entity reference. self.pieces.append("&%(ref)s" % locals()) # standard HTML entities are closed with a semicolon; other entities are not if htmlentitydefs.entitydefs.has_key(ref): self.pieces.append(";") def handle_data(self, text): # called for each block of plain text, i.e. outside of any tag and # not containing any character or entity references # Store the original text verbatim. self.pieces.append(text) def handle_comment(self, text): # called for each HTML comment, e.g. # Reconstruct the original comment. # It is especially important that the source document enclose client-side # code (like Javascript) within comments so it can pass through this # processor undisturbed; see comments in unknown_starttag for details. self.pieces.append("" % locals()) def handle_pi(self, text): # called for each processing instruction, e.g. # Reconstruct original processing instruction. self.pieces.append("" % locals()) def handle_decl(self, text): # called for the DOCTYPE, if present, e.g. # # Reconstruct original DOCTYPE self.pieces.append("" % locals()) def output(self): """Return processed HTML as a single string""" return "".join(self.pieces)