Class OrderedMap

cassandra/util.py:658–766

An ordered map that accepts non-hashable types for keys. It also maintains the insertion order of items, behaving as OrderedDict in that regard. These maps are constructed and read just as normal mapping types, except that they may contain arbitrary collections and other non-hashabl

class OrderedMap(Mapping):
    '''
    An ordered map that accepts non-hashable types for keys. It also maintains the
    insertion order of items, behaving as OrderedDict in that regard. These maps
    are constructed and read just as normal mapping types, except that they may
    contain arbitrary collections and other non-hashable items as keys::

        >>> od = OrderedMap([({'one': 1, 'two': 2}, 'value'),
        ...                  ({'three': 3, 'four': 4}, 'value2')])
        >>> list(od.keys())
        [{'two': 2, 'one': 1}, {'three': 3, 'four': 4}]
        >>> list(od.values())
        ['value', 'value2']

    These constructs are needed to support nested collections in Cassandra 2.1.3+,
    where frozen collections can be specified as parameters to others::

        CREATE TABLE example (
            ...
            value map<frozen<map<int, int>>, double>
            ...
        )

    This class derives from the (immutable) Mapping API. Objects in these maps
    are not intended be modified.
    ''&#x27;

    def __init__(self, *args, **kwargs):
        if len(args) > 1:
            raise TypeError('expected at most 1 arguments, got %d' % len(args))

        self._items = []
        self._index = {}
        if args:
            e = args[0]
            if callable(getattr(e, 'keys', None)):
                for k in e.keys():
                    self._insert(k, e[k])
            else:
                for k, v in e:
                    self._insert(k, v)

        for k, v in kwargs.items():
            self._insert(k, v)

    def _insert(self, key, value):
        flat_key = self._serialize_key(key)
        i = self._index.get(flat_key, -1)
        if i >= 0:
            self._items[i] = (key, value)
        else:
            self._items.append((key, value))
            self._index[flat_key] = len(self._items) - 1

    __setitem__ = _insert

    def __getitem__(self, key):
        try: