# Source code for fontTools.misc.classifyTools

    """ fontTools.misc.classifyTools.py -- tools for classifying things.
    """

    class Classifier(object):
        """
        Main Classifier object, used to classify things into similar sets.
        """

        def __init__(self, sort=True):
            self._things = set()  # set of all things known so far
            self._sets = []  # list of class sets produced so far
            self._mapping = {}  # map from things to their class set
            self._dirty = False
            self._sort = sort

        def add(self, set_of_things):
            """
            Add a set to the classifier.  Any iterable is accepted.
            """
            if not set_of_things:
                return

            self._dirty = True

            things, sets, mapping = self._things, self._sets, self._mapping

            s = set(set_of_things)
            intersection = s.intersection(things)  # existing things
            s.difference_update(intersection)  # new things
            difference = s
            del s

            # Add new class for new things
            if difference:
                things.update(difference)
                sets.append(difference)
                for thing in difference:
                    mapping[thing] = difference
            del difference

            while intersection:
                # Take one item and process the old class it belongs to
                old_class = mapping[next(iter(intersection))]
                old_class_intersection = old_class.intersection(intersection)

                # Update old class to remove items from new set
                old_class.difference_update(old_class_intersection)

                # Remove processed items from todo list
                intersection.difference_update(old_class_intersection)

                # Add new class for the intersection with old class
                sets.append(old_class_intersection)
                for thing in old_class_intersection:
                    mapping[thing] = old_class_intersection
                del old_class_intersection

        def update(self, list_of_sets):
            """
            Add a a list of sets to the classifier.  Any iterable of iterables is accepted.
            """
            for s in list_of_sets:
                self.add(s)

        def _process(self):
            if not self._dirty:
                return

            # Do any deferred processing
            sets = self._sets
            self._sets = [s for s in sets if s]

            if self._sort:
                self._sets = sorted(self._sets, key=lambda s: (-len(s), sorted(s)))

            self._dirty = False

        # Output methods

        def getThings(self):
            """Returns the set of all things known so far.

            The return value belongs to the Classifier object and should NOT
            be modified while the classifier is still in use.
            """
            self._process()
            return self._things

        def getMapping(self):
            """Returns the mapping from things to their class set.

            The return value belongs to the Classifier object and should NOT
            be modified while the classifier is still in use.
            """
            self._process()
            return self._mapping

        def getClasses(self):
            """Returns the list of class sets.

            The return value belongs to the Classifier object and should NOT
            be modified while the classifier is still in use.
            """
            self._process()
            return self._sets

    def classify(list_of_sets, sort=True):
        """
        Takes a iterable of iterables (list of sets from here on; but any
        iterable works.), and returns the smallest list of sets such that
        each set, is either a subset, or is disjoint from, each of the input
        sets.

        In other words, this function classifies all the things present in
        any of the input sets, into similar classes, based on which sets
        things are a member of.

        If sort=True, return class sets are sorted by decreasing size and
        their natural sort order within each class size.  Otherwise, class
        sets are returned in the order that they were identified, which is
        generally not significant.

        >>> classify([]) == ([], {})
        True
        >>> classify([[]]) == ([], {})
        True
        >>> classify([[], []]) == ([], {})
        True
        >>> classify([[1]]) == ([{1}], {1: {1}})
        True
        >>> classify([[1,2]]) == ([{1, 2}], {1: {1, 2}, 2: {1, 2}})
        True
        >>> classify([[1],[2]]) == ([{1}, {2}], {1: {1}, 2: {2}})
        True
        >>> classify([[1,2],[2]]) == ([{1}, {2}], {1: {1}, 2: {2}})
        True
        >>> classify([[1,2],[2,4]]) == ([{1}, {2}, {4}], {1: {1}, 2: {2}, 4: {4}})
        True
        >>> classify([[1,2],[2,4,5]]) == (
        ...     [{4, 5}, {1}, {2}], {1: {1}, 2: {2}, 4: {4, 5}, 5: {4, 5}})
        True
        >>> classify([[1,2],[2,4,5]], sort=False) == (
        ...     [{1}, {4, 5}, {2}], {1: {1}, 2: {2}, 4: {4, 5}, 5: {4, 5}})
        True
        >>> classify([[1,2,9],[2,4,5]], sort=False) == (
        ...     [{1, 9}, {4, 5}, {2}], {1: {1, 9}, 2: {2}, 4: {4, 5}, 5: {4, 5},
        ...     9: {1, 9}})
        True
        >>> classify([[1,2,9,15],[2,4,5]], sort=False) == (
        ...     [{1, 9, 15}, {4, 5}, {2}], {1: {1, 9, 15}, 2: {2}, 4: {4, 5},
        ...     5: {4, 5}, 9: {1, 9, 15}, 15: {1, 9, 15}})
        True
        >>> classes, mapping = classify([[1,2,9,15],[2,4,5],[15,5]], sort=False)
        >>> set([frozenset(c) for c in classes]) == set(
        ...     [frozenset(s) for s in ({1, 9}, {4}, {2}, {5}, {15})])
        True
        >>> mapping == {1: {1, 9}, 2: {2}, 4: {4}, 5: {5}, 9: {1, 9}, 15: {15}}
        True
        """
        classifier = Classifier(sort=sort)
        classifier.update(list_of_sets)
        return classifier.getClasses(), classifier.getMapping()

    if __name__ == "__main__":
        import sys, doctest

        sys.exit(doctest.testmod(optionflags=doctest.ELLIPSIS).failed)