>#foreach $element in $list $element #end
> 1 2 3 4
>
>If all directives are pluggable then there
>is nothing specific in the grammar to
>catch a #foreach $element in $list. You are basically
>looking for #anything, then a list of arguments.
>In the above example it's not possible to tell
>that (4) is in the body of the #foreach without
>giving the parser a hint i.e. the number of
>arguments to the directive. So a #foreach has
>three arguments so what follows must be the
>body of loop.
Actually, what I did in WM is a little more complicated, but this is
close. Each directive has a directive descriptor, which includes a list of
argument descriptors. Argument descriptors describe an argument, and there
are defined types for Conditional, LValue, RValue, Keyword, Block, etc. So
the argument list for #foreach would be: ( LValue, Keyword("in"), RValue,
Block )
While this solves the problem of backward compatibility in WM, it does make
the parser more complicated. Jason's idea of delimiting the argument list
with ( .. ) seems to work, although you're still going to want to be able
to say that some directives require a block (like #if and #foreach) and
some don't (like #set.) I think this will still require some, but fewer,
JAVACODE productions.
--
Brian Goetz
Quiotix Corporation
[EMAIL PROTECTED] Tel: 650-843-1300 Fax: 650-324-8032
http://www.quiotix.com
