document the exceptions raised by sgmllib, htmllib, and HTMLParser

Doc/lib/libhtmllib.tex

@@ -35,8 +35,8 @@ The interface to feed data to an instance is through the \method{feed()}
 method, which takes a string argument.  This can be called with as
 little or as much text at a time as desired; \samp{p.feed(a);
 p.feed(b)} has the same effect as \samp{p.feed(a+b)}.  When the data
-contains complete HTML tags, these are processed immediately;
-incomplete elements are saved in a buffer.  To force processing of all
+contains complete HTML markup constructs, these are processed immediately;
+incomplete constructs are saved in a buffer.  To force processing of all
 unprocessed data, call the \method{close()} method.
 
 For example, to parse the entire contents of a file, use:
@@ -60,7 +60,7 @@ should define the \method{do_\var{tag}()} method.
 
 \end{itemize}
 
-The module defines a single class:
+The module defines a parser class and an exception:
 
 \begin{classdesc}{HTMLParser}{formatter}
 This is the basic HTML parser class.  It supports all entity names
@@ -68,6 +68,12 @@ required by the XHTML 1.0 Recommendation (\url{http://www.w3.org/TR/xhtml1}).
 It also defines handlers for all HTML 2.0 and many HTML 3.0 and 3.2 elements.
 \end{classdesc}
 
+\begin{excdesc}{HTMLParseError}
+Exception raised by the \class{HTMLParser} class when it encounters an
+error while parsing.
+\versionadded{2.4}
+\end{excdesc}
+
 
 \begin{seealso}
   \seemodule{formatter}{Interface definition for transforming an
@@ -118,7 +124,8 @@ implementation adds a textual footnote marker using an index into the
 list of hyperlinks created by \method{anchor_bgn()}.
 \end{methoddesc}
 
-\begin{methoddesc}{handle_image}{source, alt\optional{, ismap\optional{, align\optional{, width\optional{, height}}}}}
+\begin{methoddesc}{handle_image}{source, alt\optional{, ismap\optional{,
+                                 align\optional{, width\optional{, height}}}}}
 This method is called to handle images.  The default implementation
 simply passes the \var{alt} value to the \method{handle_data()}
 method.

Doc/lib/libhtmlparser.tex

@@ -4,6 +4,8 @@
 \declaremodule{standard}{HTMLParser}
 \modulesynopsis{A simple parser that can handle HTML and XHTML.}
 
+\versionadded{2.2}
+
 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}  Unlike the parser in
@@ -23,6 +25,17 @@ that end tags match start tags or call the end-tag handler for
 elements which are closed implicitly by closing an outer element.
 \end{classdesc}
 
+An exception is defined as well:
+
+\begin{excdesc}{HTMLParseError}
+Exception raised by the \class{HTMLParser} class when it encounters an
+error while parsing.  This exception provides three attributes:
+\member{msg} is a brief message explaining the error, \member{lineno}
+is the number of the line on which the broken construct was detected,
+and \member{offset} is the number of characters into the line at which
+the construct starts.
+\end{excdesc}
+
 
 \class{HTMLParser} instances have the following methods:
 

Doc/lib/libsgmllib.tex

@@ -14,7 +14,6 @@ only exists as a base for the \refmodule{htmllib} module.  Another
 HTML parser which supports XHTML and offers a somewhat different
 interface is available in the \refmodule{HTMLParser} module.
 
-
 \begin{classdesc}{SGMLParser}{}
 The \class{SGMLParser} class is instantiated without arguments.
 The parser is hardcoded to recognize the following
@@ -40,7 +39,16 @@ spaces, tabs, and newlines are allowed between the trailing
 \end{itemize}
 \end{classdesc}
 
-\class{SGMLParser} instances have the following interface methods:
+A single exception is defined as well:
+
+\begin{excdesc}{SGMLParseError}
+Exception raised by the \class{SGMLParser} class when it encounters an
+error while parsing.
+\versionadded{2.1}
+\end{excdesc}
+
+
+\class{SGMLParser} instances have the following methods:
 
 
 \begin{methoddesc}{reset}{}