pyfuck.py

## Import System for writing to STDOUT ##
import sys


class PyFuck(object):
    def __init__(self, string, memory_limit=30, log=False,
                 outfile=sys.stdout):
        ## This is the string (IE: BrainFuck Code) that the class will parse
        self.string = string
        ## The current position of the counter
        self.counter = 0
        ## The complete memory set (Limited from 30,000 to 300)
        self.memory = [0] * memory_limit
        ## This is used when a loop is declared as the start of said loop
        self.loop = 0
        ## This is for debug purposes
        self.log = log
        self.out = outfile

    ## Declare the Parser
    def parse(self):
        ## Correspond the characters to their appropriate functions
        options = {
            '+': self.plus,
            '-': self.minus,
            '>': self.forward,
            '<': self.backward,
            '[': self.begin_loop,
            ']': self.end_loop,
            '.': self.output
        }

        ## Using a while loop instead of a for loop so we can manipulate 'i'
        i = 0
        while i < len(self.string):
            ## Current character being parsed
            current_char = self.string[i]

            if current_char not in options:
                i += 1
                continue

            i = options[current_char](i)

            ## Log each transaction
            if self.log:
                print("Transaction: (counter:" + str(self.counter)+") " +
                      str(current_char) + " Result: " +
                      str(self.memory[self.counter]) + " (i: " + str(i) + ")")

                ## Write a newline at the end
        self.out.write('\n')

    ## Add 1 to the current cell
    def plus(self, i):
        self.memory[self.counter] += 1
        return i + 1

    ## Minus 1 from the current cell
    def minus(self, i):
        self.memory[self.counter] -= 1
        return i + 1

    ## Move the counter forward
    def forward(self, i):
        self.counter += 1
        return i + 1

    ## Move the counter backward
    def backward(self, i):
        self.counter -= 1
        return i + 1

    ## Begin the loop
    def begin_loop(self, i):
        ## Mark where the loop started
        self.loop = i
        return i + 1

    ## End the loop
    def end_loop(self, i):
        ## If the current cell isn't 0, then return to where the loop started
        if(self.memory[self.counter] != 0):
            return self.loop
        return i + 1

    ## Outputs the current cell
    def output(self, i):
        self.out.write(chr(self.memory[self.counter]))
        return i + 1

    ## Dump the entire memory set. Useful for debugging
    def dump(self):
        for i in self.memory:
            print(i)


def parse(string, memory_limit=30, log=False, outfile=sys.stdout):
    PyFuck(string, memory_limit, log, outfile).parse()