operator.py

from state import Jug

class Operator:
    def __init__(self, from_, to):
        self.from_ = from_
        self.to = to

    def precondition_fulfilled(self, jug):
        return jug.contents[self.from_] != 0 and jug.contents[self.to] != Jug.CAPACITIES[self.to]
    
    def use(self, jug):
        result = Jug()

        volume = min(jug.contents[self.from_], Jug.CAPACITIES[self.to] - jug.contents[self.to])
        index_untouched = next(filter(lambda i: i not in (self.from_, self.to), Jug.INDICES))

        result.contents[self.from_] = jug.contents[self.from_] - volume
        result.contents[self.to] = jug.contents[self.to] + volume
        result.contents[index_untouched] = jug.contents[index_untouched]

        return result
    
    def __str__(self):
        return f"Operator [From={self.from_}, To={self.to}]"
    
if __name__ == "__main__":
    o1 = Operator(from_= 0, to= 1)
    print(o1)

    jug = Jug([2, 0, 3])
    print("-------------")
    print("Jug: ", jug)
    print("Precondition: ", o1.precondition_fulfilled(jug))
    print("After: ", o1.use(jug))