Befungeインタプリタ

befunge.py

import random
import sys

class Stack:
  def __init__(self):
    self.stack = []

  def append(self, v):
    self.stack.append(v)

  def pop(self):
    if len(self.stack) <= 0:
      return 0

    return self.stack.pop()

class Interpreter:
  def __init__(self, program):
    self.pos = (0, 0)
    self.dir = (1, 0)
    self.stack = Stack()
    self.program = [list(line) for line in program.splitlines()]
    self.running = False

  def step(self):
    x, y = self.pos
    op = self.program[y][x]

    # Befunge-93
    if op == '+':
      a = self.stack.pop()
      b = self.stack.pop()
      self.stack.append(a + b)
    elif op == '-':
      a = self.stack.pop()
      b = self.stack.pop()
      self.stack.append(b - a)
    elif op == '*':
      a = self.stack.pop()
      b = self.stack.pop()
      self.stack.append(a * b) 
    elif op == '/':
      a = self.stack.pop()
      b = self.stack.pop()
      self.stack.append(b // a)
    elif op == '%':
      a = self.stack.pop()
      b = self.stack.pop()
      self.stack.append(b % a)
    elif op == '!':
      a = self.stack.pop()
      self.stack.append(1 if a == 0 else 0)
    elif op == '`':
      a = self.stack.pop()
      b = self.stack.pop()
      self.stack.append(1 if b > a else 0)
    elif op == '>': 
      self.dir = (1, 0)
    elif op == '<':
      self.dir = (-1, 0)
    elif op == '^':
      self.dir = (0, -1)
    elif op == 'v':
      self.dir = (0, 1)
    elif op == '?':
      self.dir = (
        (1, 0),
        (-1, 0),
        (0, 1),
        (0, -1)
      )[random.randint(0, 3)]
    elif op == '_':
      a = self.stack.pop()
      self.dir = (1, 0) if a == 0 else (-1, 0)
    elif op == '|':
      a = self.stack.pop()
      self.dir = (0, 1) if a == 0 else (0, -1)
    elif op == '"':
      x, y = self.move()
      while self.program[y][x] != '"':
        self.stack.append(ord(self.program[y][x]))
        x, y = self.move()
    elif op == ':':
      a = self.stack.pop()
      self.stack.append(a)
      self.stack.append(a)
    elif op == '\\':
      a = self.stack.pop()
      b = self.stack.pop()
      self.stack.append(a)
      self.stack.append(b)
    elif op == '$':
      self.stack.pop()
    elif op == '.':
      a = self.stack.pop()
      sys.stdout.write('{} '.format(a))
    elif op == ',':
      a = self.stack.pop()
      sys.stdout.write(chr(a))
    elif op == '#':
      self.move() 
    elif op == 'g': 
      y = self.stack.pop()
      x = self.stack.pop()
      self.stack.append(ord(self.program[y][x]))
    elif op == 'p':
      y = self.stack.pop()
      x = self.stack.pop()
      v = self.stack.pop()
      self.program[y][x] = chr(v)
    elif op == '&':
      a = ''
      while not a.isdigit():
        a = input('int> ')
      self.stack.append(int(a))
    elif op == '~':
      a = input('char> ')
      self.stack.append(ord(a[0]))
    elif op == '@':
      self.running = False
    elif op.isdigit():
      self.stack.append(int(op))

    # Funge-98
    elif op == ';':
      x, y = self.move()
      while self.program[y][x] != ';':
        x, y = self.move()
    elif 'a' <= op <= 'f':
      self.stack.append(int(op, 16))

  def move(self):
    x, y = self.pos
    dx, dy = self.dir

    x += dx
    if x < 0:
      x = len(self.program[y]) - 1
    if x >= len(self.program[y]):
      x = 0

    y += dy
    if y < 0:
      y = len(self.program) - 1
    if y >= len(self.program):
      y = 0

    self.pos = (x, y)
    return self.pos

  def interpret(self):
    self.running = True
    while self.running:
      self.step()
      self.move()

if __name__ == '__main__':
  import argparse

  parser = argparse.ArgumentParser(description='Befunge Interpreter')
  parser.add_argument('file', nargs='?', help='file to execute')
  args = parser.parse_args()

  if args.file is None:
    program = sys.stdin.read()
  else:
    with open(args.file, 'r') as f:
      program = f.read()

  interpreter = Interpreter(program)
  interpreter.interpret()