unlambda.py

[wfocke at mothership.phoenixdsl.com]

Simon Brunning taunted:
>> From: Ben Wolfson [<address elided>]
>> There are probably some memory issues.
>
>I think that you have all sorts of issues. ;)
>
>What's next on your list - Brainf***, Orthogonal, or the classic INTERCAL?

I wrote this a year ago, and had more sense than to let it out.
Now you've driven me to it, you beastly man.

but-I-think-it'll-all-work-out-in-the-end-
as-long-as-no-one-does-Befunge-ly y'rs

Warren Focke

------------------- bfi.py --------------------
import array, sys

default_size = 30000

point_big = 1
point_neg = 2
loop_open = 4
loop_close = 8

class BrainFork:

    def __init__(self, size=default_size, typecode='B',
                 istream=sys.stdin, ostream=sys.stdout):
        self.point = 0
        self.size = size
        self.array = array.array(typecode, [0] * size)
        self.istream = istream
        self.ostream = ostream
        self._pmax = self.point
        self._pmin = self.point
        self._error = 0

    def interp(self, string):
        iptr = 0
        lim = len(string)
        while iptr < lim:
            command = string[iptr]
            if command == '+':
                self.array[self.point] = self.array[self.point] + 1
            elif command == '-':
                self.array[self.point] = self.array[self.point] - 1
            elif command == '>':
                self.point = self.point + 1
                if self.point > self._pmax:
                    self._pmax = self.point
                    if self.point >= self.size:
                        self._error = self._error | point_big
            elif command == '<':
                self.point = self.point - 1
                if self.point < self._pmin:
                    self._pmin = self.point
                    if self.point < 0:
                        self._error = self._error | point_neg
            elif command == '[':
                # scan forward to find end of loop
                depth = 1
                lstart = iptr + 1
                while iptr < lim:
                    iptr = iptr + 1
                    command = string[iptr]
                    if command == '[':
                        depth = depth + 1
                    elif command == ']':
                        depth = depth - 1
                        if depth == 0:
                            # loop is done
                            break
                else:
                    # the loop did not finish
                    self._error = self._error | loop_close
                while self.array[self.point]:
                    self.interp(string[lstart:iptr])
            elif command == ']':
                # loop close without an open
                self._error = self._error | loop_open
            elif command == '.':
                self.ostream.write(chr(self.array[self.point]))
                self.ostream.flush()
            elif command == ',':
                self.array[self.point] = ord(self.istream.read(1))
            else:
                pass
            iptr = iptr + 1


if __name__ == '__main__':
    if len(sys.argv) > 1:
        file = open(sys.argv[1])
    else:
        file = sys.stdin

    bfi = BrainFork()
    script = file.read()
    bfi.interp(script)

-- 
fnord