"""Base class for creating HTML processing modules This class is designed to take HTML as input and spit out equivalent HTML as output. By itself it's not very interesting; you use it by subclassing it and providing the methods you need to create your HTML transformation. This program is part of "Dive Into Python", a free Python book for experienced programmers. Visit http://diveintopython.org/ for the latest version. """ __author__ = "Mark Pilgrim (mark@diveintopython.org)" __version__ = "$Revision: 1.2 $" __date__ = "$Date: 2004/05/05 21:57:19 $" __copyright__ = "Copyright (c) 2001 Mark Pilgrim" __license__ = "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("%(tag)s>" % 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("%(text)s>" % 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) if __name__ == "__main__": for k, v in globals().items(): print k, "=", v