YACC

I am trying to implement if/if else statements.

for example I want
if(a<b){ statement }
to print something like
"ifbegin a<b" + whatever statement prints + "ifend".

however for
if(a<b){statement1}else{statement2}
it should print
"ifelsebegin a<b" + whatever statement1 prints + " else " + ifelseend

is this possible? I tried the code below but ifelse and if are printed after the statements.

IF '(' expr ')' singlestatement ELSE singlestatement {printf("ifelse")} ;
|
IF '(' expr ')' singlestatement %prec IFX {printf("if")};

These don't look like s-expressions.

Semantics Engineering with PLT Redex

YAK YAK?

>>1
Because it's evaluating the singlestatements before these two rules, of course it'll print before (assuming you're just printf'ing in them). Have it propagate some value up to these two statements ($$ = ...), so you can do some shit with it, like as $5 and $7.

http://www.gnu.org/s/bison/manual/bison.html#Semantic-Actions

and yes I realize that's for bison, but fucking close enough.

>>5
>>6
returning a value won't be enough. It has to call a function before and after singlestatements and these functions are different for if and if/else structures.

I kinda solved it, now statements write things into different buffers, and these buffers are printed in right order in if statement. however there are still problems with this approach.

Is there any real purpose to printing the crap? Or is it purely for ``debugging'' purposes?