import sys
import parser

class Compiler:
    def __init__(self, stmts):
        self.instrs = []
        self.labeli = 0
        for st in stmts:
            self.preorder(st)
        for i in self.instrs:
            sys.stdout.write(i)
        print("EXIT")

    def fresh_label(self):
        self.labeli += 1
        return "L%d" % self.labeli

    def preorder(self, node):
        return getattr(self, "t_" + node.__class__.__name__.lower())(node)

    def t_assign(self, node):
        self.preorder(node.exp)
        self.instrs.append("VAR_SET %s\n" % node.name)

    def t_var(self, node):
        self.instrs.append("VAR_LOOKUP %s\n" % node.name)

    def t_int(self, node):
        self.instrs.append("INT %s\n" % node.val)

    def t_bin_op(self, node):
        self.preorder(node.lhs)
        self.preorder(node.rhs)
        if node.op == "<":
            self.instrs.append("LESS_THAN\n")
        elif node.op == "+":
            self.instrs.append("ADD\n")
        elif node.op == "-":
            self.instrs.append("SUB\n")
        else:
            print(node.op)
            print("Unknown instruction '%s'" % node.op)

    def t_while(self, node):
        startl = self.fresh_label()
        endl = self.fresh_label()
        self.instrs.append("%s: " % startl)
        self.preorder(node.cond)
        self.instrs.append("JEQ %s\n" % endl)
        for stmt in node.body:
            self.preorder(stmt)
        self.instrs.append("JMP %s\n" % startl)
        self.instrs.append("%s: " % endl)

    def t_print(self, node):
        self.preorder(node.exp)
        self.instrs.append("PRINT\n")

stmts = parser.parse(open(sys.argv[1]).read())
Compiler(stmts)