Lab Script

class Exp:

	label = None 
	value = None 
	e1, e2 = None, None 

	def __init__(self):
		pass 

	def __str__(self):

		rInt = lambda x: "Int {0!s}".format(x)
		r    = lambda label: lambda x, y: "{0!s} ({1!s}) ({2!s})".format(label, x, y)

		return foldE(rInt, r("Add"), r("Min"), r("Mul"), self)

		# if self.label == "EInt":
		# 	return "EInt {0!s}".format(self.value)
		# else:
		# 	return "{0!s} ({1!s}) ({2!s})".format(self.label, self.e1, self.e2)

	def __eq__(self, other):
		pair = (self.label, other.label)
		if pair == ("EInt", "EInt"):
			return self.value == other.value
		else:
			return self.label == other.label and self.e1 == other.e1 and self.e2 == other.e2

	def eval(self):
		rInt = lambda x: x
		rAdd = lambda x, y: x + y
		rMin = lambda x, y: x - y
		rMul = lambda x, y: x * y
		return foldE(rInt, rAdd, rMin, rMul, self)

	def depth(self):
		rInt = lambda x: 1
		r    = lambda x, y: 1 + max (x, y)
		return foldE(rInt, r, r, r, self)


def foldE(rInt, rAdd, rMin, rMul, exp):
	if exp.label == "EInt":
		return rInt(exp.value)
	elif exp.label == "EAdd":
		r1 = foldE(rInt, rAdd, rMin, rMul, exp.e1)
		r2 = foldE(rInt, rAdd, rMin, rMul, exp.e2)
		return rAdd(r1, r2)
	elif exp.label == "EMin":
		r1 = foldE(rInt, rAdd, rMin, rMul, exp.e1)
		r2 = foldE(rInt, rAdd, rMin, rMul, exp.e2)
		return rMin(r1, r2)
	elif exp.label == "EMul":
		r1 = foldE(rInt, rAdd, rMin, rMul, exp.e1)
		r2 = foldE(rInt, rAdd, rMin, rMul, exp.e2)
		return rMul(r1, r2)
	else:
		pass



def EInt(v):
	ret = Exp()
	ret.label = "EInt"
	ret.value = v 
	return ret 

def EAdd(e1, e2):
	ret = Exp()
	ret.label = "EAdd"
	ret.e1 = e1 
	ret.e2 = e2 
	return ret 

def EMin(e1, e2):
	ret = Exp()
	ret.label = "EMin"
	ret.e1 = e1 
	ret.e2 = e2 
	return ret 

def EMul(e1, e2):
	ret = Exp()
	ret.label = "EMul"
	ret.e1 = e1 
	ret.e2 = e2 
	return ret 





testvalue = EMin (EAdd(EInt(1), EInt(2)), (EMul (EInt(3), EAdd(EInt(4), EInt(5)))))

print(testvalue)
print(testvalue.eval())
# print(testvalue.depth())