139 lines
3.7 KiB
Python
139 lines
3.7 KiB
Python
"""
|
|
Utility functions.
|
|
"""
|
|
|
|
import warnings
|
|
from collections import OrderedDict
|
|
from contextlib import contextmanager
|
|
|
|
# Python 2/3 independant dict iteration
|
|
iteritems = getattr(dict, 'iteritems', dict.items)
|
|
itervalues = getattr(dict, 'itervalues', dict.values)
|
|
|
|
|
|
class LRUCache:
|
|
# @param capacity, an integer
|
|
def __init__(self, capacity=None):
|
|
self.capacity = capacity
|
|
self.__cache = OrderedDict()
|
|
|
|
@property
|
|
def lru(self):
|
|
return list(self.__cache.keys())
|
|
|
|
@property
|
|
def length(self):
|
|
return len(self.__cache)
|
|
|
|
def clear(self):
|
|
self.__cache.clear()
|
|
|
|
def __len__(self):
|
|
return self.length
|
|
|
|
def __contains__(self, item):
|
|
return item in self.__cache
|
|
|
|
def __setitem__(self, key, value):
|
|
self.set(key, value)
|
|
|
|
def __delitem__(self, key):
|
|
del self.__cache[key]
|
|
|
|
def __getitem__(self, key):
|
|
return self.get(key)
|
|
|
|
def get(self, key, default=None):
|
|
value = self.__cache.get(key)
|
|
if value:
|
|
del self.__cache[key]
|
|
self.__cache[key] = value
|
|
return value
|
|
return default
|
|
|
|
def set(self, key, value):
|
|
if self.__cache.get(key):
|
|
del self.__cache[key]
|
|
self.__cache[key] = value
|
|
else:
|
|
self.__cache[key] = value
|
|
# Check, if the cache is full and we have to remove old items
|
|
# If the queue is of unlimited size, self.capacity is NaN and
|
|
# x > NaN is always False in Python and the cache won't be cleared.
|
|
if self.capacity is not None and self.length > self.capacity:
|
|
self.__cache.popitem(last=False)
|
|
|
|
|
|
# Source: https://github.com/PythonCharmers/python-future/blob/466bfb2dfa36d865285dc31fe2b0c0a53ff0f181/future/utils/__init__.py#L102-L134
|
|
def with_metaclass(meta, *bases):
|
|
"""
|
|
Function from jinja2/_compat.py. License: BSD.
|
|
|
|
Use it like this::
|
|
|
|
class BaseForm(object):
|
|
pass
|
|
|
|
class FormType(type):
|
|
pass
|
|
|
|
class Form(with_metaclass(FormType, BaseForm)):
|
|
pass
|
|
|
|
This requires a bit of explanation: the basic idea is to make a
|
|
dummy metaclass for one level of class instantiation that replaces
|
|
itself with the actual metaclass. Because of internal type checks
|
|
we also need to make sure that we downgrade the custom metaclass
|
|
for one level to something closer to type (that's why __call__ and
|
|
__init__ comes back from type etc.).
|
|
|
|
This has the advantage over six.with_metaclass of not introducing
|
|
dummy classes into the final MRO.
|
|
"""
|
|
|
|
class Metaclass(meta):
|
|
__call__ = type.__call__
|
|
__init__ = type.__init__
|
|
|
|
def __new__(cls, name, this_bases, d):
|
|
if this_bases is None:
|
|
return type.__new__(cls, name, (), d)
|
|
return meta(name, bases, d)
|
|
|
|
return Metaclass('temporary_class', None, {})
|
|
|
|
|
|
@contextmanager
|
|
def catch_warning(warning_cls):
|
|
with warnings.catch_warnings():
|
|
warnings.filterwarnings('error', category=warning_cls)
|
|
|
|
yield
|
|
|
|
|
|
class FrozenDict(dict):
|
|
def __hash__(self):
|
|
return hash(tuple(sorted(self.items())))
|
|
|
|
def _immutable(self, *args, **kws):
|
|
raise TypeError('object is immutable')
|
|
|
|
__setitem__ = _immutable
|
|
__delitem__ = _immutable
|
|
clear = _immutable
|
|
update = _immutable
|
|
setdefault = _immutable
|
|
pop = _immutable
|
|
popitem = _immutable
|
|
|
|
|
|
def freeze(obj):
|
|
if isinstance(obj, dict):
|
|
return FrozenDict((k, freeze(v)) for k, v in obj.items())
|
|
elif isinstance(obj, list):
|
|
return tuple(freeze(el) for el in obj)
|
|
elif isinstance(obj, set):
|
|
return frozenset(obj)
|
|
else:
|
|
return obj
|