Whitespace Interpreter

Whitespace.py

import sys

class Stream:

    def __init__(self, data):
        self.data = list(data)
        self.seeker = 0
        self.length = len(self.data)
        self.labels = {}
        self.update()

    def update(self):
        self.token = self.data[self.seeker]

    def next(self):
        self.seeker += 1
        self.update()
        #if self.token not in (SPACE, LF, TAB):
        #    self.next()

    def mark(self, label):
        self.labels[label] = self.seeker

    def jump(self, label):
        self.seeker = self.labels[label]

    def hasnext(self):
        return not self.seeker == self.length -1


SPACE = ' '
TAB = '\t'
LF = '\n'

class Whitespace:

    def __init__(self, data):
        self.stack = []
        self.stream = Stream(data)

    def eval(self):
        while self.stream.hasnext():
            self.imp()

    def imp(self):
        
        if self.stream.token == SPACE:
            self.stream.next()
            self.stack_manipulation()
        elif self.stream.token == LF:
            self.stream.next()
            self.flow_control()
        else:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                self.arithmetic()
            elif self.stream.token == TAB:
                self.stream.next()
                self.heap_access()
            elif self.stream.token == LF:
                self.stream.next()
                self.io()

    def stack_manipulation(self):
        
        if self.stream.token == SPACE:
            self.stream.next()
            var = self.get_num()
            stack.append(var)

        elif self.stream.token == LF:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                var = self.stack[-1]
                self.stack.append(var)

            elif self.stream.token == TAB:
                self.stream.next()
                a = self.stack.pop()
                b = self.stack.pop()
                self.stack.append(a)
                self.stack.append(b)

            elif self.stream.token == LF:
                self.stream.next()
                self.stack.pop()

        elif self.stream.token == TAB:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                var = self.get_num()
                a = self.stack[-var]
                self.stack.append(a)

            elif self.stream.token == LF:
                self.stream.next()
                var = self.get_num()
                self.stack = self.stack[:-(var+1)]+self.stack[-1]

    def arithmetic(self):
        
        if self.stream.token == SPACE:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                a = self.stack.pop()
                b = self.stack.pop()
                self.stack.append(a+b)

            elif self.stream.token == TAB:
                self.stream.next()
                a = self.stack.pop()
                b = self.stack.pop()
                self.stack.append(b-a)

            elif self.stream.token == LF:
                self.stream.next()
                a = self.stack.pop()
                b = self.stack.pop()
                self.stack.append(a*b)

        elif self.stream.token == TAB:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                a = self.stack.pop()
                b = self.stack.pop()
                self.stack.append(b/a)

            elif self.stream.token == TAB:
                self.stream.next()
                a = self.stack.pop()
                b = self.stack.pop()
                self.stack.append(b%a)

    def heap_access(self):
        print 'Unsupported'

    def flow_control(self):
        
        if self.stream.token == SPACE:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                var = self.get_num()
                self.stream.mark(var)

            elif self.stream.token == TAB:
                self.stream.next()
                print 'Unsupported'

            elif self.stream.token == LF:
                self.stream.next()
                var = self.get_num()
                self.stream.jump(var)
                
        elif self.stream.token == TAB:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                var = self.get_num()
                if self.stack[-1] == 0:
                    self.stream.jump(var)
            elif self.stream.token == TAB:
                self.stream.next()
                var = self.get_num()
                if self.stack[-1] < 0:
                    self.stream.jump(var)
            elif self.stream.token == LF:
                self.stream.next()
                print 'Unsupported'

        elif self.stream.token == LF:
            self.stream.next()

            if self.stream.token == LF:
                self.stream.next()
                sys.exit(0)

    
    def io(self):
        
        if self.stream.token == SPACE:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                sys.stdout.write(chr(self.stack[-1]))
            elif self.stream.token == TAB:
                self.stream.next()
                sys.stdout.write(self.stack[-1])

        elif self.stream.token == TAB:
            self.stream.next()

            if self.stream.token == SPACE:
                self.stream.next()
                var = ord(sys.stdin.read(1))
                self.stack.append(var)
            elif self.stream.token == TAB:
                self.stream.next()
                var = int(sys.stdin.read(1))
                self.stack.append(var)

    def get_num(self):
        
        if self.stream.token == SPACE:
            sign = 1
        elif self.stream.token == TAB:
            sign = -1
        self.stream.next()
        
        var = 0
        while not self.stream.token == LF:
            if self.stream.token == SPACE:
               var *= 2
            elif self.stream.token == TAB:
                var *= 2
                var += 1
            self.stream.next()
        self.stream.next()

        return var

if __name__ == '__main__':
    data = raw_input()
    Whitespace(data).eval()