BrainFuck Interpreter

bf.py

import sys
import time
import os

class _Getch:
    """Gets a single character from standard input.  Does not echo to the
screen."""
    def __init__(self):
        try:
            self.impl = _GetchWindows()
        except ImportError:
            self.impl = _GetchUnix()

    def __call__(self): return self.impl()


class _GetchUnix:
    def __init__(self):
        import tty, sys

    def __call__(self):
        import sys, tty, termios
        fd = sys.stdin.fileno()
        old_settings = termios.tcgetattr(fd)
        try:
            tty.setraw(sys.stdin.fileno())
            ch = sys.stdin.read(1)
        finally:
            termios.tcsetattr(fd, termios.TCSADRAIN, old_settings)
        return ch


class _GetchWindows:
    def __init__(self):
        import msvcrt

    def __call__(self):
        import msvcrt
        return msvcrt.getch()


getch = _Getch()

code = open(sys.argv[1], "r").read()

code = ''.join([x for x in code if x in "<>+-,.[]#"])

if code[0] == "#":
	debug = True
else:
	debug = False

code = code.replace("#","")

def bmap(s):
	st = []
	bm = {}
	
	for i in range(len(s)):
		if s[i] == "[":
			st.append(i)
		elif s[i] == "]":
			a = st.pop()
			bm[a] = i
			bm[i] = a
		
	return bm

bm = bmap(code)

clen = 10
cells = [0]*clen
cellsf = ""
arr = [""]*clen
pout = []
ci = 0
ptr = 0

if debug:
	while ci < len(code):
		ins = code[ci]
		
		if ins == ">":
			ptr += 1
			if ptr == len(cells):
				cells += [0]
		elif ins == "<":
			if ptr <= 0:
				ptr = 0
			else:
				ptr -= 1
		elif ins == "+":
			cells[ptr] = (cells[ptr]+1)%255
		elif ins == "-":
			cells[ptr] -= 1
			if cells[ptr] == -1:
				cells[ptr] = 255
		elif ins == "[" and cells[ptr] == 0:
			ci = bm[ci]
		elif ins == "]" and cells[ptr] != 0:
			ci = bm[ci]
		elif ins == ".":
			pout.append(chr(cells[ptr]))
		elif ins == ",":
			print("Provide input.")
			cells[ptr] = ord(getch())
		
		cellsf = "|"+'|'.join([str(x) for x in cells])+"|"
		
		start = 0
		end = min([len(code),20])
		carr = [" "]*(end)
		
		
		if ci == 0:
			pass
		elif ci >= end:
			diff = ci - end
			end += diff
			start += diff
		elif ci < start:
			diff = start - ci
			start -= diff
			end -= diff
		
		if ci-start == len(carr):
			start += 1
			end += 1
			
		codef = "|"+code[start:end]+"|"
		print("Code tape:")
		print(codef)
		carr[ci-start] = "^"
		carr = " "+''.join(carr)+" "
		print(carr)
		
		print("Memory tape: ")
		arr = [[" "]*len(str(x)) for x in cells]
		arr[ptr][0] = "^"
		arr = " "+' '.join([''.join(x) for x in arr])
		
		#os.system("cls||clear")
		print(cellsf)
		print(arr)
		print("\n")
		print("Output: \n"+''.join(pout))
		print("\n")
		time.sleep(0.05)
		
		ci += 1
else:
	while ci < len(code):
		ins = code[ci]
		
		if ins == ">":
			ptr += 1
			if ptr == len(cells):
				cells += [0]
		elif ins == "<":
			if ptr <= 0:
				ptr = 0
			else:
				ptr -= 1
		elif ins == "+":
			cells[ptr] = (cells[ptr]+1)%255
		elif ins == "-":
			cells[ptr] -= 1
			if cells[ptr] == -1:
				cells[ptr] = 255
		elif ins == "[" and cells[ptr] == 0:
			ci = bm[ci]
		elif ins == "]" and cells[ptr] != 0:
			ci = bm[ci]
		elif ins == ".":
			sys.stdout.write(chr(cells[ptr]))
		elif ins == ",":
			print("Provide input.")
			cells[ptr] = ord(getch())
		
		ci += 1