90 lines
2.4 KiB
Python
90 lines
2.4 KiB
Python
'''brainfuck interpreter adapted from (public domain) code at
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http://brainfuck.sourceforge.net/brain.py'''
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import re
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import random
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from util import hook
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BUFFER_SIZE = 5000
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MAX_STEPS = 1000000
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@hook.command('brainfuck')
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@hook.command
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def bf(inp):
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"""bf <prog> -- Executes <prog> as Brainfuck code."""
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program = re.sub('[^][<>+-.,]', '', inp)
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# create a dict of brackets pairs, for speed later on
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brackets = {}
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open_brackets = []
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for pos in range(len(program)):
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if program[pos] == '[':
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open_brackets.append(pos)
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elif program[pos] == ']':
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if len(open_brackets) > 0:
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brackets[pos] = open_brackets[-1]
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brackets[open_brackets[-1]] = pos
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open_brackets.pop()
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else:
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return 'unbalanced brackets'
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if len(open_brackets) != 0:
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return 'unbalanced brackets'
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# now we can start interpreting
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ip = 0 # instruction pointer
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mp = 0 # memory pointer
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steps = 0
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memory = [0] * BUFFER_SIZE # initial memory area
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rightmost = 0
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output = "" # we'll save the output here
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# the main program loop:
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while ip < len(program):
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c = program[ip]
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if c == '+':
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memory[mp] += 1 % 256
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elif c == '-':
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memory[mp] -= 1 % 256
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elif c == '>':
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mp += 1
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if mp > rightmost:
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rightmost = mp
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if mp >= len(memory):
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# no restriction on memory growth!
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memory.extend([0] * BUFFER_SIZE)
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elif c == '<':
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mp -= 1 % len(memory)
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elif c == '.':
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output += chr(memory[mp])
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if len(output) > 500:
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break
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elif c == ',':
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memory[mp] = random.randint(1, 255)
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elif c == '[':
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if memory[mp] == 0:
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ip = brackets[ip]
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elif c == ']':
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if memory[mp] != 0:
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ip = brackets[ip]
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ip += 1
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steps += 1
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if steps > MAX_STEPS:
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if output == '':
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output = '(no output)'
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output += '[exceeded {} iterations]'.format(MAX_STEPS)
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break
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stripped_output = re.sub(r'[\x00-\x1F]', '', output)
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if stripped_output == '':
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if output != '':
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return 'no printable output'
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return 'no output'
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return stripped_output[:430].decode('utf8', 'ignore')
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