#! /usr/bin/python

#############################################################################
##                                                                         ##
## bfi.py --- BrainFuck interpreter                                        ##
##                                                                         ##
## Copyright (C) 2002  Philippe Biondi <biondi@cartel-securite.fr>         ##
##                                                                         ##
## This program is free software; you can redistribute it and/or modify it ##
## under the terms of the GNU General Public License as published by the   ##
## Free Software Foundation; either version 2, or (at your option) any     ##
## later version.                                                          ##
##                                                                         ##
## This program is distributed in the hope that it will be useful, but     ##
## WITHOUT ANY WARRANTY; without even the implied warranty of              ##
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU       ##
## General Public License for more details.                                ##
##                                                                         ##
#############################################################################



import sys,string,os

f=open(sys.argv[1]);
prog=string.join(f.readlines())

tape = [0]
ip = 0
p = 0
level = 0

while 1:
    op = 1;
    x = prog[ip]
    ip += 1

    if x == '+':
        tape[p] = (tape[p]+1)%256
    elif x == '-':
        tape[p] = (tape[p]-1)%256
    elif x == '>':
        p += 1
        if len(tape) <= p:
            tape.append(0)
    elif x == '<':
        if p:
            p -= 1
        else:
            debug("Warning: inserting one element at the begining\n");
            tape.insert(0,0)
    elif x == '.':
        os.write(1,chr(tape[p]%256))
    elif x == ',':
        tape[p] = ord(os.read(0,1)[0])
    elif x == '[':
        if not tape[p]:
            while 1:
                if prog[ip] == '[':
                    level += 1;
                if prog[ip] == ']':
                    if level:
                        level -= 1
                    else:
                        break
                ip += 1
            ip += 1
    elif x == ']':
        ip -= 2;
        while 1:
            if prog[ip] == ']':
                level += 1
            if prog[ip] == '[':
                if level:
                    level -= 1
                else:
                    break
            ip -= 1
    else:
        op = 0

    if op:
        t2 = tape[:]
        t2[p] = "<%i>" % t2[p]
	os.write(2, "%s %s %i %s\n" % (x,t2.__repr__(),ip,prog[ip]))

    if ip >= len(prog):
        break;