Rebol 2: Using a parse rule to check input without executing code

Question

Let's suppose you have a rule like the one below from the Rebol docs on parsing.

If you wanted to check some input against a rule just to validate it, but without having the contents of the parentheses evaluated, how can you do it?

Is there a way that easily lets you just validate inputs against a rule without having the content of the parentheses being evaluated?

rule: [
    set action ['buy | 'sell]
    set number integer!
    'shares 'at
    set price money!
    (either action = 'sell [
            print ["income" price * number]
            total: total + (price * number)
        ] [
            print ["cost" price * number]
            total: total - (price * number)
        ]
    )
]

Answer 1

Depends if you mean parse input or parse rules.

For parse rules you need some special flag and function that will take care of it:

do?: true
parse-do: function [code] [if do? [do code]]
rule: ['a (parse-do [print "got it"])]
parse [a] rule
do?: false
parse [a] rule

For parse input use INTO:

>> parse [paren (1 + 1)]['paren into [integer! '+ integer!]]
== true