Add documentatin for PARSE-HTML-FORMS.

doc/latex/httpd.tex

@@ -622,6 +622,27 @@ that following procedure cause an error if called:
   \ex{eval-safely} returns \sharpf.
 \end{defundesc}
 
+\section{Writing Request Handlers}
+
+\subsection{Parsing HTML Forms}
+
+In HTML forms, field data are turned into a single string, of the form
+\texttt{\synvar{name}=\synvar{val}\&\synvar{name}=\synvar{val}\ldots}.
+The \ex{parse-html-forms} structure provides simple functionality to
+parse these strings.
+
+\defun{parse-html-form-query}{string}{alist}
+\begin{desc}
+  This parses \verb|"foo=x&bar=y"| into \verb|(("foo" . "x") ("bar" .
+  "y"))|.  Substrings are plus-decoded (i.-e.\ plus characters are
+  turned into spaces) and then URI-decoded.
+
+  This implementation is
+  slightly sleazy as it will successfully parse a string like
+  \verb|"a&b=c&d=f"| into \verb|(("a&b" . "c") ("d" .  "f"))| without
+  a complaint.
+\end{desc}
+
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