A toy stack machine implementation in Python to illustrate match statements

stack_machine.py

from enum import Enum, auto

from collections import namedtuple


class Operation(Enum):

    PUSH = auto()
    STORE = auto()
    LOAD = auto()
    ADD = auto()
    MUL = auto()
    GOTO = auto()
    PRINT = auto()

    def __repr__(self):
        return f"<{self.name}>"


class VM:

    def __init__(self):
        self.stack = []
        self.environment = {}
        self.program_pointer = 0

    def push(self, value):
        self.stack.append(value)


    def print(self):
        print(self.stack.pop())


    def add(self):
        self.stack.append(self.stack.pop() + self.stack.pop())


    def divide(self):
        self.stack.append(self.stack.pop() / self.stack.pop())


    def multiply(self):
        self.stack.append(self.stack.pop() * self.stack.pop())


    def store(self, key):
        self.environment[key] = self.stack.pop()


    def load(self, key):
        self.stack.append(self.environment[key])


    @property
    def current_instruction(self):
        return self.current_program[self.program_pointer]


    def advance_pointer(self):
        self.program_pointer += 1


    def reset_pointer(self):
        self.program_pointer = 0


    def interpret(self, program):
        self.current_program = program
        while self.program_pointer < len(program):
            match self.current_instruction:
                case Operation.PRINT, None:
                    self.print()
                case Operation.PUSH, x:
                    self.push(x)
                case Operation.STORE, x:
                    self.store(x)
                case Operation.LOAD, x:
                    self.load(x)
                case Operation.ADD, None:
                    self.add()
                case Operation.MUL, None:
                    self.multiply()
            self.advance_pointer()
        self.reset_pointer()


if __name__ == "__main__":
    # Define a program in our stack machine
    program = [
        (Operation.PUSH, 10),
        (Operation.STORE, "x"),
        (Operation.PUSH, 20),
        (Operation.STORE, "y"),
        (Operation.PUSH, 10),
        (Operation.STORE, "z"),
        (Operation.PUSH, "hello"),
        (Operation.STORE, "a"),
        (Operation.LOAD, "x"),
        (Operation.LOAD, "y"),
        (Operation.ADD, None),
        (Operation.LOAD, "z"),
        (Operation.ADD, None),
        (Operation.STORE, "v"),
        (Operation.PUSH, "world"),
        (Operation.STORE, "b"),
        (Operation.LOAD, "b"),
        (Operation.LOAD, "a"),
        (Operation.ADD, None),
        (Operation.STORE, "c"),
        (Operation.LOAD, "v"),
        (Operation.PRINT, None),
        (Operation.LOAD, "c"),
        (Operation.PRINT, None),
        (Operation.LOAD, "a"),
        (Operation.PRINT, None)
    ]
    vm = VM()
    vm.interpret(program)

    # The program above should be semantically equivalent to the following Python program
    x = 10
    y = 20
    z = 10
    a = "hello"
    v = x + y + z
    b = "world"
    c = a + b
    print(v)
    print(c)
    print(a)