Naive Brainfuck Interpreter

bf.py

# https://en.wikipedia.org/wiki/Brainfuck
import sys
from typing import List


class BF:
    def __init__(self, code: str) -> None:
        self.memory: List[int] = [0] * 30000
        self.code = code
        self.ip: int = 0
        self.dp: int = 0

    def __readChar(self, c: str) -> None:
        # print(f"readChar: {c}")
        self.memory[self.dp] = ord(c[0])

    def __putChar(self) -> None:
        # print(f"putChar: {self.memory[self.dp]}")
        print(chr(int(self.memory[self.dp])), end='')

    def execute(self) -> None:
        while self.ip < len(self.code):
            ins = self.code[self.ip]

            if ins == "+":
                self.memory[self.dp] += 1
            elif ins == "-":
                self.memory[self.dp] -= 1
            elif ins == ">":
                self.dp += 1
            elif ins == "<":
                self.dp -= 1
            elif ins == ",":
                self.__readChar(ins)
            elif ins == ".":
                self.__putChar()
            elif ins == "[":
                if self.memory[self.dp] == 0:
                    depth = 1
                    while depth != 0:
                        self.ip += 1
                        if self.code[self.ip] == '[':
                            depth += 1
                        elif self.code[self.ip] == ']':
                            depth -= 1
            elif ins == "]":
                if self.memory[self.dp] != 0:
                    depth = 1
                    while depth != 0:
                        self.ip -= 1
                        if self.code[self.ip] == ']':
                            depth += 1
                        elif self.code[self.ip] == '[':
                            depth -= 1

            self.ip += 1


if __name__ == "__main__":
    if len(sys.argv) != 2:
        print("usage: python3 bf.py <filename>.b")
        sys.exit()
    code = None
    with open(sys.argv[1]) as f:
        code = f.read()
        bf = BF(code)
        bf.execute()