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authorFred Drake <fdrake@acm.org>1996-10-08 21:51:49 (GMT)
committerFred Drake <fdrake@acm.org>1996-10-08 21:51:49 (GMT)
commit42439ad738e53804676937d6621be69a24222836 (patch)
treeaddf6ad255e7e76a7fbfb6e5fd007ce5a158ed05 /Doc/lib
parent58124880ccb7bbd09a49956c69940f19e246de2c (diff)
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(libsgmllib.tex): Revised documentation for SGML support.
Diffstat (limited to 'Doc/lib')
-rw-r--r--Doc/lib/libsgmllib.tex105
1 files changed, 76 insertions, 29 deletions
diff --git a/Doc/lib/libsgmllib.tex b/Doc/lib/libsgmllib.tex
index 129bdd9..23d8504 100644
--- a/Doc/lib/libsgmllib.tex
+++ b/Doc/lib/libsgmllib.tex
@@ -12,7 +12,7 @@ exists as a basis for the \code{htmllib} module.
\stmodindex{htmllib}
In particular, the parser is hardcoded to recognize the following
-elements:
+constructs:
\begin{itemize}
@@ -22,13 +22,15 @@ Opening and closing tags of the form
``\code{</\var{tag}>}'', respectively.
\item
-Character references of the form ``\code{\&\#\var{name};}''.
+Numeric character references of the form ``\code{\&\#\var{name};}''.
\item
Entity references of the form ``\code{\&\var{name};}''.
\item
-SGML comments of the form ``\code{<!--\var{text}>}''.
+SGML comments of the form ``\code{<!--\var{text}-->}''. Note that
+spaces, tabs, and newlines are allowed between the trailing
+``\code{>}'' and the immediately preceeding ``\code{--}''.
\end{itemize}
@@ -63,41 +65,83 @@ define additional processing at the end of the input, but the
redefined version should always call \code{SGMLParser.close()}.
\end{funcdesc}
+\begin{funcdesc}{handle_starttag}{tag\, method\, attributes}
+This method is called to handle start tags for which either a
+\code{start_\var{tag}()} or \code{do_\var{tag}()} method has been
+defined. The \code{tag} argument is the name of the tag converted to
+lower case, and the \code{method} argument is the bound method which
+should be used to support semantic interpretation of the start tag.
+The \var{attributes} argument is a list of (\var{name}, \var{value})
+pairs containing the attributes found inside the tag's \code{<>}
+brackets. The \var{name} has been 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 \code{unknown_starttag('a', [('href',
+'http://www.cwi.nl/')])}. The base implementation simply calls
+\code{method} with \code{attributes} as the only argument.
+\end{funcdesc}
+
+\begin{funcdesc}{handle_endtag}{tag\, method}
+
+This method is called to handle endtags for which an
+\code{end_\var{tag}()} method has been defined. The \code{tag}
+argument is the name of the tag converted to lower case, and the
+\code{method} argument is the bound method which should be used to
+support semantic interpretation of the end tag. If no
+\code{end_\var{tag}()} method is defined for the closing element, this
+handler is not called. The base implementation simply calls
+\code{method}.
+\end{funcdesc}
+
+\begin{funcdesc}{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{funcdesc}
+
\begin{funcdesc}{handle_charref}{ref}
This method is called to process a character reference of the form
-``\code{\&\#\var{ref};}'' where \var{ref} is a decimal number in the
+``\code{\&\#\var{ref};}''. In the base implementation, \var{ref} must
+be a decimal number in the
range 0-255. It translates the character to \ASCII{} and calls the
method \code{handle_data()} with the character as argument. If
\var{ref} is invalid or out of range, the method
-\code{unknown_charref(\var{ref})} is called instead.
+\code{unknown_charref(\var{ref})} is called to handle the error. A
+subclass must override this method to provide support for named
+character entities.
\end{funcdesc}
\begin{funcdesc}{handle_entityref}{ref}
-This method is called to process an entity reference of the form
-``\code{\&\var{ref};}'' where \var{ref} is an alphabetic entity
+This method is called to process a general entity reference of the form
+``\code{\&\var{ref};}'' where \var{ref} is an general entity
reference. It looks for \var{ref} in the instance (or class)
-variable \code{entitydefs} which should give the entity's translation.
+variable \code{entitydefs} which should be a mapping from entity names
+to corresponding translations.
If a translation is found, it calls the method \code{handle_data()}
with the translation; otherwise, it calls the method
-\code{unknown_entityref(\var{ref})}.
+\code{unknown_entityref(\var{ref})}. The default \code{entitydefs}
+defines translations for \code{\&amp;}, \code{\&apos}, \code{\&gt;},
+\code{\&lt;}, and \code{\&quot;}.
\end{funcdesc}
-\begin{funcdesc}{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.
+\begin{funcdesc}{handle_comment}{comment}
+This method is called when a comment is encountered. The
+\code{comment} argument is a string containing the text between the
+``\code{<!--}'' and ``\code{-->}'' delimiters, but not the delimiters
+themselves. For example, the comment ``\code{<!--text-->}'' will
+cause this method to be called with the argument \code{'text'}. The
+default method does nothing.
+\end{funcdesc}
+
+\begin{funcdesc}{report_unbalanced}{tag}
+This method is called when an end tag is found which does not
+correspond to any open element.
\end{funcdesc}
\begin{funcdesc}{unknown_starttag}{tag\, attributes}
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 \var{attributes} argument is a list of
-(\var{name}, \var{value}) pairs containing the attributes found inside
-the tag's \code{<>} brackets. The \var{name} has been 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 \code{unknown_starttag('a', [('href', 'http://www.cwi.nl/')])}.
+does nothing.
\end{funcdesc}
\begin{funcdesc}{unknown_endtag}{tag}
@@ -107,9 +151,9 @@ does nothing.
\end{funcdesc}
\begin{funcdesc}{unknown_charref}{ref}
-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.
+This method is called to process unresolvable numeric character
+references. It is intended to be overridden by a derived class; the
+base class implementation does nothing.
\end{funcdesc}
\begin{funcdesc}{unknown_entityref}{ref}
@@ -127,22 +171,25 @@ case:
\begin{funcdesc}{start_\var{tag}}{attributes}
This method is called to process an opening tag \var{tag}. It has
preference over \code{do_\var{tag}()}. The \var{attributes} argument
-has the same meaning as described for \code{unknown_tag()} above.
+has the same meaning as described for \code{handle_starttag()} above.
\end{funcdesc}
\begin{funcdesc}{do_\var{tag}}{attributes}
This method is called to process an opening tag \var{tag} that does
not come with a matching closing tag. The \var{attributes} argument
-has the same meaning as described for \code{unknown_tag()} above.
+has the same meaning as described for \code{handle_starttag()} above.
\end{funcdesc}
\begin{funcdesc}{end_\var{tag}}{}
This method is called to process a closing tag \var{tag}.
\end{funcdesc}
-Note that the parser maintains a stack of opening tags for which no
-matching closing tag has been found yet. Only tags processed by
-\code{start_\var{tag}()} are pushed on this stack. Definition of a
+Note that the parser maintains a stack of open elements for which no
+end tag has been found yet. Only tags processed by
+\code{start_\var{tag}()} are pushed on this stack. Definition of an
\code{end_\var{tag}()} method is optional for these tags. For tags
processed by \code{do_\var{tag}()} or by \code{unknown_tag()}, no
-\code{end_\var{tag}()} method must be defined.
+\code{end_\var{tag}()} method must be defined; if defined, it will not
+be used. If both \code{start_\var{tag}()} and \code{do_\var{tag}()}
+methods exist for a tag, the \code{start_\var{tag}()} method takes
+precedence.