expr.fortob

# infix expression parser

@expr[
	$expr=[
		$!=\;
		%a=$!$term.apply:\\;
		[$!.seekString="+"\.if:['='],[$!.seekString="-"\.if:['=']]].while: [
			$a=$!.nextString="+"\.if:[
				$a+$!$term.apply:
			], [
				$a-$!$term.apply:
			]\\;
		]\;
		$a
	]\;
	$term=[
                $!=\;
                %b=$!$prim.apply:\\;
                [$!.seekString="*"\.if:['='],[$!.seekString="/"\.if:['=']]].while: [
                        $b=$!.nextString="*"\.if:[
                                $b*$!$prim.apply:
                        ], [
                                $b/$!$prim.apply:
                        ]\\;
                ]\;
                $b
        ]\;
	$prim=[
		$!=\;
		$!.seekString="("\.if: [
			$!.accept:"("\;
			$expr.apply:$!\
			$!.accept:")"\;
		], [
			$!.nextNumber
		]
	]\;
	$\.push:$expr.apply:$!\\;
]\;

""+expr 2+(3*4)\.println;