This module defines a class HTMLParser which serves as the
basis for parsing text files formatted in HTML (HyperText
Mark-up Language) and XHTML. Unlike the parser in
htmllib, this parser is not based on the SGML parser in
sgmllib.
classHTMLParser(
)
The HTMLParser class is instantiated without arguments.
An HTMLParser instance is fed HTML data and calls handler functions
when tags begin and end. The HTMLParser class is meant to be
overridden by the user to provide a desired behavior.
Unlike the parser in htmllib, this parser does not check
that end tags match start tags or call the end-tag handler for
elements which are closed implicitly by closing an outer element.
An exception is defined as well:
exceptionHTMLParseError
Exception raised by the HTMLParser class when it encounters an
error while parsing. This exception provides three attributes:
msg is a brief message explaining the error, lineno
is the number of the line on which the broken construct was detected,
and offset is the number of characters into the line at which
the construct starts.
HTMLParser instances have the following methods:
reset(
)
Reset the instance. Loses all unprocessed data. This is called
implicitly at instantiation time.
feed(
data)
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(
)
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 the HTMLParser base class
method close().
getpos(
)
Return current line number and offset.
get_starttag_text(
)
Return the text of the most recently opened start tag. This should
not normally be needed for structured processing, but may be useful in
dealing with HTML ``as deployed'' or for re-generating input with
minimal changes (whitespace between attributes can be preserved,
etc.).
handle_starttag(
tag, attrs)
This method is called to handle the start of a tag. It is intended to
be overridden by a derived class; the base class implementation does
nothing.
The tag argument is the name of the tag converted to
lower case. The attrs argument is a list of (name,
value) pairs containing the attributes found inside the tag's
<> brackets. The name will be 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
"handle_starttag('a', [('href', 'http://www.cwi.nl/')])".
handle_startendtag(
tag, attrs)
Similar to handle_starttag(), but called when the parser
encounters an XHTML-style empty tag (<a .../>). This method
may be overridden by subclasses which require this particular lexical
information; the default implementation simple calls
handle_starttag() and handle_endtag().
handle_endtag(
tag)
This method is called to handle the end tag of an element. It is
intended to be overridden by a derived class; the base class
implementation does nothing. The tag argument is the name of
the tag converted to lower case.
handle_data(
data)
This method is called to process arbitrary data. It is intended to be
overridden by a derived class; the base class implementation does
nothing.
handle_charref(
name)
This method is called to
process a character reference of the form "&#ref;". It
is intended to be overridden by a derived class; the base class
implementation does nothing.
handle_entityref(
name)
This method is called to process a general entity reference of the
form "&name;" where name is an general entity
reference. It is intended to be overridden by a derived class; the
base class implementation does nothing.
handle_comment(
data)
This method is called when a comment is encountered. The
comment argument is a string containing the text between the
"--" and "--" delimiters, but not the delimiters
themselves. For example, the comment "<!--text-->" will
cause this method to be called with the argument 'text'. It is
intended to be overridden by a derived class; the base class
implementation does nothing.
handle_decl(
decl)
Method called when an SGML declaration is read by the parser. The
decl parameter will be the entire contents of the declaration
inside the <!...> markup. It is intended to be overridden
by a derived class; the base class implementation does nothing.
handle_pi(
data)
Method called when a processing instruction is encountered. The
data parameter will contain the entire processing instruction.
For example, for the processing instruction <?proc color='red'>,
this method would be called as handle_pi("proc color='red'"). It
is intended to be overridden by a derived class; the base class
implementation does nothing.
Note:
The HTMLParser class uses the SGML syntactic rules for
processing instructions. An XHTML processing instruction using the
trailing "?" will cause the "?" to be included in
data.
