pocketpy/python/_set.py

class set:
    def __init__(self, iterable=None):
        iterable = iterable or []
        self._a = {}
        for item in iterable:
            self.add(item)

    def add(self, elem):
        self._a[elem] = None
        
    def discard(self, elem):
        if elem in self._a:
            del self._a[elem]

    def remove(self, elem):
        del self._a[elem]
        
    def clear(self):
        self._a.clear()

    def update(self,other):
        for elem in other:
            self.add(elem)
        return self

    def __len__(self):
        return len(self._a)
    
    def copy(self):
        return set(self._a.keys())
    
    def __and__(self, other):
        ret = set()
        for elem in self:
            if elem in other:
                ret.add(elem)
        return ret
    
    def __or__(self, other):
        ret = self.copy()
        for elem in other:
            ret.add(elem)
        return ret

    def __sub__(self, other):
        ret = set() 
        for elem in self:
            if elem not in other: 
                ret.add(elem) 
        return ret
    
    def __xor__(self, other): 
        ret = set() 
        for elem in self: 
            if elem not in other: 
                ret.add(elem) 
        for elem in other: 
            if elem not in self: 
                ret.add(elem) 
        return ret

    def union(self, other):
        return self | other

    def intersection(self, other):
        return self & other

    def difference(self, other):
        return self - other

    def symmetric_difference(self, other):      
        return self ^ other
    
    def __eq__(self, other):
        return self.__xor__(other).__len__() == 0

    def isdisjoint(self, other):
        return self.__and__(other).__len__() == 0
    
    def issubset(self, other):
        return self.__sub__(other).__len__() == 0
    
    def issuperset(self, other):
        return other.__sub__(self).__len__() == 0

    def __contains__(self, elem):
        return elem in self._a
    
    def __repr__(self):
        if len(self) == 0:
            return 'set()'
        return '{'+ ', '.join([repr(i) for i in self._a.keys()]) + '}'
    
    def __iter__(self):
        return iter(self._a.keys())