# coding=utf-8
from collections import Iterable, Mapping
from flyforms.compatibility import string_types
UNSET = object() # the default mark for not set values
is_set = lambda value: value is not UNSET
# Supported types for JSON encoding and decoding operations
jsonify_types = (bool, int, float, Iterable, Mapping) + string_types
[docs]class FrozenDict(Mapping):
"""
Immutable dictionary implementation
stolen from StackOverflow_
.. _StackOverflow: http://stackoverflow.com/questions/2703599/what-would-a-frozen-dict-be
"""
def __init__(self, *args, **kwargs):
self._d = dict(*args, **kwargs)
self._hash = None
def __iter__(self):
return iter(self._d)
def __len__(self):
return len(self._d)
def __getitem__(self, key):
return self._d[key]
def __hash__(self):
if self._hash is None:
self._hash = 0
for pair in self.iteritems():
self._hash ^= hash(pair)
return self._hash