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author | Fred Drake <fdrake@acm.org> | 2001-05-30 04:59:00 (GMT) |
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committer | Fred Drake <fdrake@acm.org> | 2001-05-30 04:59:00 (GMT) |
commit | 3b755d43ac9f732d4bbb8622e9f98b874476c663 (patch) | |
tree | 18d371a1f52e90c7ceb7ec4a414dc6bbe0c9d97a | |
parent | 0b76d3a8d1a3007d90f28763c5a907359d6ef538 (diff) | |
download | cpython-3b755d43ac9f732d4bbb8622e9f98b874476c663.zip cpython-3b755d43ac9f732d4bbb8622e9f98b874476c663.tar.gz cpython-3b755d43ac9f732d4bbb8622e9f98b874476c663.tar.bz2 |
Michel Pelletier <michel@digicool.com>:
Documentation for the HTMLParser module, with small changes by FLD.
-rw-r--r-- | Doc/lib/libhtmlparser.tex | 136 |
1 files changed, 136 insertions, 0 deletions
diff --git a/Doc/lib/libhtmlparser.tex b/Doc/lib/libhtmlparser.tex new file mode 100644 index 0000000..e8b4dd9 --- /dev/null +++ b/Doc/lib/libhtmlparser.tex @@ -0,0 +1,136 @@ +\section{\module{HTMLParser} --- + Simple HTML and XHTML parser} + +\declaremodule{standard}{HTMLParser} +\modulesynopsis{A simple parser that can handle HTML and XHTML.} + +This module defines a class \class{HTMLParser} which serves as the +basis for parsing text files formatted in HTML\index{HTML} (HyperText +Mark-up Language) and XHTML.\index{XHTML} + + +\begin{classdesc}{HTMLParser}{} +The \class{HTMLParser} class is instantiated without arguments. + +An HTMLParser instance is fed HTML data and calls handler functions +when tags begin and end. The \class{HTMLParser} class is meant to be +overridden by the user to provide a desired behavior. +\end{classdesc} + + +\class{HTMLParser} instances have the following methods: + +\begin{methoddesc}{reset}{} +Reset the instance. Loses all unprocessed data. This is called +implicitly at instantiation time. +\end{methoddesc} + +\begin{methoddesc}{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 \method{close()} is called. +\end{methoddesc} + +\begin{methoddesc}{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 \class{HTMLParser} base class +method \method{close()}. +\end{methoddesc} + +\begin{methoddesc}{getpos}{} +Return current line number and offset. +\end{methoddesc} + +\begin{methoddesc}{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.). +\end{methoddesc} + +\begin{methoddesc}{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 \var{tag} argument is the name of the tag converted to +lower case. The \var{attrs} argument is a list of \code{(\var{name}, +\var{value})} pairs containing the attributes found inside the tag's +\code{<>} brackets. The \var{name} will be translated to lower case +and double quotes and backslashes in the \var{value} have been +interpreted. For instance, for the tag \code{<A +HREF="http://www.cwi.nl/">}, this method would be called as +\samp{handle_starttag('a', [('href', 'http://www.cwi.nl/')])}. +\end{methoddesc} + +\begin{methoddesc}{handle_startendtag}{tag, attrs} +Similar to \method{handle_starttag()}, but called when the parser +encounters an XHTML-style empty tag (\code{<a .../>}). This method +may be overridden by subclasses which require this particular lexical +information; the default implementation simple calls +\method{handle_starttag()} and \method{handle_endtag()}. +\end{methoddesc} + +\begin{methoddesc}{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 \var{tag} argument is the name of +the tag converted to lower case. +\end{methoddesc} + +\begin{methoddesc}{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. +\end{methoddesc} + +\begin{methoddesc}{handle_charref}{name} This method is called to +process a character reference of the form \samp{\&\#\var{ref};}. It +is intended to be overridden by a derived class; the base class +implementation does nothing. +\end{methoddesc} + +\begin{methoddesc}{handle_entityref}{name} +This method is called to process a general entity reference of the +form \samp{\&\var{name};} where \var{name} is an general entity +reference. It is intended to be overridden by a derived class; the +base class implementation does nothing. +\end{methoddesc} + +\begin{methoddesc}{handle_comment}{data} +This method is called when a comment is encountered. The +\var{comment} argument is a string containing the text between the +\samp{<!--} and \samp{-->} delimiters, but not the delimiters +themselves. For example, the comment \samp{<!--text-->} will cause +this method to be called with the argument \code{'text'}. It is +intended to be overridden by a derived class; the base class +implementation does nothing. +\end{methoddesc} + +\begin{methoddesc}{handle_decl}{decl} +Method called when an SGML declaration is read by the parser. The +\var{decl} parameter will be the entire contents of the declaration +inside the \code{<!}...\code{>} markup.It is intended to be overridden +by a derived class; the base class implementation does nothing. +\end{methoddesc} + + +\subsection{Example HTML Parser \label{htmlparser-example}} + +As a basic example, below is a very basic HTML parser that uses the +\class{HTMLParser} class to print out tags as they are encountered: + +\begin{verbatim} +from HTMLParser import HTMLParser + +class MyHTMLParser(HTMLParser): + + def handle_starttag(self, tag, attrs): + print "Encountered the beginning of a %s tag" % tag + + def handle_endtag(self, tag): + print "Encountered the end of a %s tag" % tag +\end{verbatim} |