Python Program

#! /usr/bin/env python3 import fileinput import sys # used to store a parsed TL expressions which are # constant numbers, constant strings, variable names, and binary expressions class Expr : def __init__(self,op1,operator,op2=None): self.op1 = op1 self.operator = operator self.op2 = op2 def __str__(self): if self.op2 == None: return self.operator + " " + self.op1 else: return self.op1 + " " + self.operator + " " + self.op2 # evaluate this expression given the environment of the symTable def eval(self, symTable): if self.operator == "var": return symTable[op1] else: return 0 # used to store a parsed TL statement class Stmt : def __init__(self,keyword,exprs): self.keyword = keyword self.exprs = exprs def __str__(self): others = "" for exp in self.exprs: others = others + " " + str(exp) return self.keyword + others # perform/execute this statement given the environment of the symTable def perform(self, symTable): print ("Doing: " + str(self))