Add memoziation decorator

powerline/lib/memoize.py

@@ -0,0 +1,44 @@
+# -*- coding: utf-8 -*-
+
+import time
+
+
+class memoize(object):
+	'''Memoization decorator with timout.
+
+	http://code.activestate.com/recipes/325905-memoize-decorator-with-timeout/
+	'''
+	_caches = {}
+	_timeouts = {}
+
+	def __init__(self, timeout):
+		self.timeout = timeout
+
+	def collect(self):
+		'''Clear cache of results which have timed out.
+		'''
+		for func in self._caches:
+			cache = {}
+			for key in self._caches[func]:
+				if (time.time() - self._caches[func][key][1]) < self._timeouts[func]:
+					cache[key] = self._caches[func][key]
+			self._caches[func] = cache
+
+	def __call__(self, f):
+		self.cache = self._caches[f] = {}
+		self._timeouts[f] = self.timeout
+
+		def func(*args, **kwargs):
+			kw = kwargs.items()
+			kw.sort()
+			key = (args, tuple(kw))
+			try:
+				v = self.cache[key]
+				if (time.time() - v[1]) > self.timeout:
+					raise KeyError
+			except KeyError:
+				v = self.cache[key] = f(*args, **kwargs), time.time()
+			return v[0]
+		func.func_name = f.func_name
+
+		return func