extends RefCounted

var state = { "foo": ["foo", "bar", "baz", "quux"], "bar": ["quux", "baz", "bar", "foo"] }

func push(stack_symbol, symbol) -> void:
	state[stack_symbol].push_back(symbol)

func peek(stack_symbol, depth : int, symbol) -> bool:
	var stack = state[stack_symbol]
	if not stack: return false
	return stack[stack.size() - depth] == symbol

func pop(stack_symbol) -> void:
	state[stack_symbol].pop_back()

func _rule_0() -> bool:
	var baz
	if not peek("foo", 0, "bar"): return false
	if baz == null and peek("foo", 1, "baz"): return false
	baz = peek("foo", 1, "baz")
	if not peek("foo", 2, "bin"): return false
	pop("foo")
	pop("foo")
	pop("foo")
	push("bar", "quux")
	push("bar", baz if baz else "baz")
	push("bar", "quin")