"""
实例：
汤宝宝坚信搭积木是人类的未来，因此开办了一家积木厂。
"""

from abc import ABC, abstractmethod


# 抽象Node接口 Shape
class Shape(ABC):
    @abstractmethod
    def accept(self, visitor: "Visitor"):
        pass

    @abstractmethod
    def claim_shape(self):
        pass


class Circle(Shape):
    def accept(self, visitor):
        visitor.visit_circle(self)

    def claim_shape(self):
        print("I am a Circle")


class Square(Shape):
    def accept(self, visitor):
        visitor.visit_square(self)

    def claim_shape(self):
        print("I am a Square")


class Triangle(Shape):
    def accept(self, visitor):
        visitor.visit_triangle(self)

    def claim_shape(self):
        print("I am a Triangle")


# 抽象Visitor接口
class Visitor(ABC):
    @abstractmethod
    def visit_circle(self, circle: Circle):
        pass

    @abstractmethod
    def visit_square(self, square: Square):
        pass

    @abstractmethod
    def visit_triangle(self, triangle: Triangle):
        pass


# 具体Visitor实现
class ShapeVisitor(Visitor):
    def visit_circle(self, circle: Circle):
        print("Visiting Circle:", end=" ")
        circle.claim_shape()

    def visit_square(self, square: Square):
        print("Visiting Square:", end=" ")
        square.claim_shape()

    def visit_triangle(self, triangle: Triangle):
        print("Visiting Triangle:", end=" ")
        triangle.claim_shape()


if __name__ == "__main__":
    print("========== 访问者模式 ==========")
    shapes = [Circle(), Square(), Triangle()]
    visitor = ShapeVisitor()
    for shape in shapes:
        shape.accept(visitor)

    print("\n======== 访问者模式结束 ========")