#! /usr/bin/python

# maybe Producer is a better name then Server?
class UniqItemServer(list):
    def __init__(self, values):
        list.__init__(self, values)
        self._index = 0

    def append(self, value):
        if value not in self:
            self += [value]

    def item_generator(self):
        while self._index < len(self)-1:
            idx = self._index
            self._index += 1
            yield self[idx]
        try:
            item = self[self._index]
        except IndexError:
            raise StopIteration
        self._index += 1
        yield item


if __name__ == '__main__':

    if 1:
        uis = UniqItemServer([])
        uis.append(1)
        uis.append(1)
        uis.append(1)
        uis.append(1)
        uis.append(1)
        assert(uis == [1])
        uis.append(1)
        uis.append(2)
        uis.append(2)
        uis.append(3)
        uis.append(3)
        assert(uis == [1, 2, 3])
        uis_gen = uis.item_generator()
        assert(uis_gen.next() == 1)
        assert(uis_gen.next() == 2)
        assert(uis_gen.next() == 3)

        try:
            uis_gen.next()
        except StopIteration: 
            # reset generator
            uis_gen = uis.item_generator()

        uis.append(4)
        uis.append(5)
        uis.append(5)
        uis.append(6)
        uis.append(6)
        uis_gen.next()
        assert(uis_gen.next() == 4)
        assert(uis_gen.next() == 5)
        assert(uis_gen.next() == 6)
        stop = False
        try: uis_gen.next()
        except StopIteration: stop = True
        assert(stop == True)
     
        uis = UniqItemServer([])   
        uis_gen = uis.item_generator()
        uis.append(1)
        uis.append(2)
        uis.append(2)
        uis.append(3)
        uis.append(3)
        assert(uis_gen.next() == 1)
        assert(uis_gen.next() == 2)
        assert(uis_gen.next() == 3)
        uis_gen = uis.item_generator()
        uis.append(4)
        uis.append(5)
        uis.append(5)
        uis.append(6)
        uis.append(6)
        uis_gen = uis.item_generator()
        assert(uis_gen.next() == 4)
        assert(uis_gen.next() == 5)
        uis.append(7)
        uis.append(8)
        uis_gen = uis.item_generator()
        assert(uis_gen.next() == 6)
        assert(uis_gen.next() == 7)
        uis_gen = uis.item_generator()
        assert(uis_gen.next() == 8)