A Python dictionary type that allows set operations for nested dictionaries.

dictset.py

class DictSet(dict):
    """
    A dictionary type that allows set operations for nested dictionaries.
    """

    def __or__(self, other):
        return self.union(other)

    def __and__(self, other):
        return self.intersection(other)

    def __sub__(self, other):
        return self.difference(other)

    def union(self, other):
        """
        Return the union of two dictionaries.

        In the case of a conflict the right operand takes precedance.
        """
        result = DictSet()

        for key in (self.keys() | other.keys()):
            if isinstance(self.get(key), dict) and isinstance(other.get(key), dict):
                result[key] = DictSet(self[key]).union(other[key])
            else:
                result[key] = other.get(key, self.get(key))

        return result

    def intersection(self, other):
        """
        Return the intersection of two dictionaries.

        In the case of a conflict neither dictionary value is present.
        """
        result = DictSet()

        for key in (self.keys() & other.keys()):
            if isinstance(self.get(key), dict) and isinstance(other.get(key), dict):
                subresult = DictSet(self[key]).intersection(other[key])
                if subresult:
                    result[key] = subresult
            elif self.get(key) == other[key]:
                result[key] = self[key]

        return result

    def difference(self, other):
        """
        Return the difference of two dictionaries.

        In the case of a conflict the left operand takes precedance.
        """
        result = DictSet()

        for key in (self.keys() | other.keys()):
            if isinstance(self.get(key), dict) and isinstance(other.get(key), dict):
                subresult = DictSet(self[key]).difference(other[key])
                if subresult:
                    result[key] = subresult
            elif self.get(key) != other.get(key):
                result[key] = self.get(key, other.get(key))

        return result