On 03/23/08 16:02, Larry Evans wrote:
On 03/22/08 22:12, Eric Niebler wrote:
Larry Evans wrote: [snip]
The following grammar I think summarizes the difference between grammar and expression:
expr //describes an expression. = terminal | expr+ //i.e. 1 or more expressions (e.g. expr<tag::plus,expr0,expr1>) ;
In addition, I wanted some way to tell what's a valid 1st arg to matches. The above description of expr is for a grammar. Now a valid 1st arg to matches would apply ::type to each node in the above tree, AFAICT. At first, I thought of:
expr_type = terminal::type | expr_type+ ;
but that would make:
( terminal::type, terminal::type, terminal::type )
a valid expresion when what's needed is:
( terminal::type, terminal::type, terminal::type )::type
OOPS (again). I guess this would produce what's needed: expr_type = terminal::type | (expr_type+)::type ;