> Even though Bison is a bottom up parser, if I need to
pass a variable's
> content top-down, what are the possible ways (except
using global
> variable)?
One way is to use the optional parameter that you can pass
to `yyparse'.
It is a `void*' that can point to an object of whatever type
you like.
You'll need to cast it to the correct type in each rule in
which you want
to access the structure, unless you're just passing it
further to a
function (which takes a `void*' argument, obviously).
You can use this object to store whatever information you
like. My parser
(for GNU 3DLDF) needs to be thread-safe, so global variables
wouldn't be a
good idea. There's a `Scanner_Type' object (this is the
type pointed to
by my `void* parameter') for each instance of `yyparse',
each of which is
in a separate thread.
It works great for me. If you want to see lots of examples,
you could
look in the files with the suffix `.w' here:
http://cvs.savannah.gnu.org/viewvc/3dldf/3dldf/Group/C
WEB/
`grep' for `parameter' and/or `Scanner_Node' (a `typedef'
for
`Scanner_Type*').
Laurence Finston
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