Table-Driven Parsing
















Show the steps of a stack-based parser.
(Compare to a derivation.)

	E -> T A
	A -> + T A | - T A | epsilon
	T -> ( E ) | 2

	input: 2 + 2

















Classwork
You may work with a partner.

Show the steps of a stack-based parser.

	S -> if E then S
	S -> E = E
	E -> 2 | x

	input: if x then x = 2

















Parse Tables
















Build a parse table for the grammar.

	E -> T A
	A -> + T A | - T A | epsilon
	T -> ( E ) | 2


















Classwork
You may work with a partner.

Build a parse table for the grammar.

	S -> if E then S
	S -> E = E
	E -> 2 | x



















What's the algorithm for table-driven parsing?

	push the start-symbol on the stack

	while (stack and input are not empty)

	  if (top-of-stack is a terminal)
	     if (top-of-stack matches input)
	        pop the stack
	        advance the input
	     else
	        report error

	  else if (top-of-stack is a nonterminal)
	     if (table[top-of-stack, input] is not blank)
		pop the stack
		push rule from table[top-of-stack, input] on the stack
	     else
	        report error

	end while