sgmllib -- Python library reference


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11.9. Standard Module sgmllib

This module defines a class SGMLParser which serves as the basis for parsing text files formatted in SGML (Standard Generalized Mark-up Language). In fact, it does not provide a full SGML parser --- it only parses SGML insofar as it is used by HTML, and the module only exists as a basis for the htmllib module. In particular, the parser is hardcoded to recognize the following elements:

The SGMLParser class must be instantiated without arguments. It has the following interface methods:

reset () -- function of module sgmllib
Reset the instance. Loses all unprocessed data. This is called implicitly at instantiation time.
setnomoretags () -- function of module sgmllib
Stop processing tags. Treat all following input as literal input (CDATA). (This is only provided so the HTML tag <PLAINTEXT> can be implemented.)
setliteral () -- function of module sgmllib
Enter literal mode (CDATA mode).
feed (data) -- function of module sgmllib
Feed some text to the parser. It is processed insofar as it consists of complete elements; incomplete data is buffered until more data is fed or close() is called.
close () -- function of module sgmllib
Force processing of all buffered data as if it were followed by an end-of-file mark. This method may be redefined by a derived class to define additional processing at the end of the input, but the redefined version should always call SGMLParser.close().
handle_charref (ref) -- function of module sgmllib
This method is called to process a character reference of the form ``&#ref;'' where ref is a decimal number in the range 0-255. It translates the character to ASCII and calls the method handle_data() with the character as argument. If ref is invalid or out of range, the method unknown_charref(ref) is called instead.
handle_entityref (ref) -- function of module sgmllib
This method is called to process an entity reference of the form ``&ref;'' where ref is an alphabetic entity reference. It looks for ref in the instance (or class) variable entitydefs which should give the entity's translation. If a translation is found, it calls the method handle_data() with the translation; otherwise, it calls the method unknown_entityref(ref).
handle_data (data) -- function of module sgmllib
This method is called to process arbitrary data. It is intended to be overridden by a derived class; the base class implementation does nothing.
unknown_starttag (tag, attributes) -- function of module sgmllib
This method is called to process an unknown start tag. It is intended to be overridden by a derived class; the base class implementation does nothing. The attributes argument is a list of (name, value) pairs containing the attributes found inside the tag's <> brackets. The name has been translated to lower case and double quotes and backslashes in the value have been interpreted. For instance, for the tag <A HREF="http://www.cwi.nl/">, this method would be called as unknown_starttag('a', [('href', 'http://www.cwi.nl/')]).
unknown_endtag (tag) -- function of module sgmllib
This method is called to process an unknown end tag. It is intended to be overridden by a derived class; the base class implementation does nothing.
unknown_charref (ref) -- function of module sgmllib
This method is called to process an unknown character reference. It is intended to be overridden by a derived class; the base class implementation does nothing.
unknown_entityref (ref) -- function of module sgmllib
This method is called to process an unknown entity reference. It is intended to be overridden by a derived class; the base class implementation does nothing.
Apart from overriding or extending the methods listed above, derived classes may also define methods of the following form to define processing of specific tags. Tag names in the input stream are case independent; the tag occurring in method names must be in lower case:

start_tag (attributes) -- function of module sgmllib
This method is called to process an opening tag tag. It has preference over do_tag(). The attributes argument has the same meaning as described for unknown_tag() above.
do_tag (attributes) -- function of module sgmllib
This method is called to process an opening tag tag that does not come with a matching closing tag. The attributes argument has the same meaning as described for unknown_tag() above.
end_tag () -- function of module sgmllib
This method is called to process a closing tag tag.
Note that the parser maintains a stack of opening tags for which no matching closing tag has been found yet. Only tags processed by start_tag() are pushed on this stack. Definition of a end_tag() method is optional for these tags. For tags processed by do_tag() or by unknown_tag(), no end_tag() method must be defined.
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