"""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("" % 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)
if __name__ == "__main__":
for k, v in globals().items():
print k, "=", v