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Mark Pilgrim
94 lines
3.7 KiB
Python
94 lines
3.7 KiB
Python
"""Base class for creating HTML processing modules
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This class is designed to take HTML as input and spit out equivalent
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HTML as output. By itself it's not very interesting; you use it by
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subclassing it and providing the methods you need to create your HTML
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transformation.
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This program is part of "Dive Into Python", a free Python book for
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experienced programmers. Visit http://diveintopython.org/ for the
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latest version.
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"""
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__author__ = "Mark Pilgrim (mark@diveintopython.org)"
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__version__ = "$Revision: 1.1 $"
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__date__ = "$Date: 2005/12/25 03:22:56 $"
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__copyright__ = "Copyright (c) 2001 Mark Pilgrim"
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__license__ = "Python"
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from sgmllib import SGMLParser
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import htmlentitydefs
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class BaseHTMLProcessor(SGMLParser):
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def reset(self):
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# extend (called by SGMLParser.__init__)
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self.pieces = []
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SGMLParser.reset(self)
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def unknown_starttag(self, tag, attrs):
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# called for each start tag
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# attrs is a list of (attr, value) tuples
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# e.g. for <pre class="screen">, tag="pre", attrs=[("class", "screen")]
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# Ideally we would like to reconstruct original tag and attributes, but
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# we may end up quoting attribute values that weren't quoted in the source
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# document, or we may change the type of quotes around the attribute value
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# (single to double quotes).
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# Note that improperly embedded non-HTML code (like client-side Javascript)
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# may be parsed incorrectly by the ancestor, causing runtime script errors.
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# All non-HTML code must be enclosed in HTML comment tags (<!-- code -->)
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# to ensure that it will pass through this parser unaltered (in handle_comment).
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strattrs = "".join([' %s="%s"' % (key, value) for key, value in attrs])
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self.pieces.append("<%(tag)s%(strattrs)s>" % locals())
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def unknown_endtag(self, tag):
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# called for each end tag, e.g. for </pre>, tag will be "pre"
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# Reconstruct the original end tag.
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self.pieces.append("</%(tag)s>" % locals())
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def handle_charref(self, ref):
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# called for each character reference, e.g. for " ", ref will be "160"
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# Reconstruct the original character reference.
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self.pieces.append("&#%(ref)s;" % locals())
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def handle_entityref(self, ref):
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# called for each entity reference, e.g. for "©", ref will be "copy"
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# Reconstruct the original entity reference.
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self.pieces.append("&%(ref)s" % locals())
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# standard HTML entities are closed with a semicolon; other entities are not
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if htmlentitydefs.entitydefs.has_key(ref):
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self.pieces.append(";")
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def handle_data(self, text):
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# called for each block of plain text, i.e. outside of any tag and
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# not containing any character or entity references
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# Store the original text verbatim.
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self.pieces.append(text)
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def handle_comment(self, text):
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# called for each HTML comment, e.g. <!-- insert Javascript code here -->
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# Reconstruct the original comment.
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# It is especially important that the source document enclose client-side
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# code (like Javascript) within comments so it can pass through this
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# processor undisturbed; see comments in unknown_starttag for details.
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self.pieces.append("<!--%(text)s-->" % locals())
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def handle_pi(self, text):
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# called for each processing instruction, e.g. <?instruction>
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# Reconstruct original processing instruction.
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self.pieces.append("<?%(text)s>" % locals())
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def handle_decl(self, text):
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# called for the DOCTYPE, if present, e.g.
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# <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
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# "http://www.w3.org/TR/html4/loose.dtd">
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# Reconstruct original DOCTYPE
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self.pieces.append("<!%(text)s>" % locals())
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def output(self):
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"""Return processed HTML as a single string"""
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return "".join(self.pieces)
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if __name__ == "__main__":
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for k, v in globals().items():
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print k, "=", v
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