Re: Sytnax Tree Construction

> I understand the generation of a tree from an expression: 4+2*var:
> +
> / \
> 4 *
> / \
> 2 var
>
> But for instance, how do you handle the actual language keywords. For
> instance, how would a tree be build for the BASIC code:
>
> DO
> x=x+2
> IF x=12
> PRINT "x=12"
> ELSEIF x=14
> PRINT "x=14"
> ELSE CALL function()
> ENDIF
> LOOP WHILE x<>20
>


why do you consider '+' to be an operation taking 2 operands?


and why don't you think of a DO WHILE as an operator too?
it also takes to operands, one being a condition and the other operand
being the statement to execute over and over again until the condition
expires.


let's keep it simple:


DO
    x=x+2
LOOP WHILE x < 20


would be something like this:




                          DO-WHILE
                        / \
                      = <
                    / \ / \
                  x + x 20
                        / \
                      x 2




when you take your expression, you know that when it holds a '+' you
have to take the 2 operands and count them together
now, for the 'DO-WHILE' node, you have to repeat the evaluation of the
left subtree until the right subtree condition evaluates to false...

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