1 files changed, 42 insertions, 0 deletions
diff --git a/powerline/lib/memoize.py b/powerline/lib/memoize.py
new file mode 100644
index 0000000..cedbe45
--- /dev/null
+++ b/powerline/lib/memoize.py
@@ -0,0 +1,42 @@
+# vim:fileencoding=utf-8:noet
+from __future__ import (unicode_literals, division, absolute_import, print_function)
+
+from functools import wraps
+
+from powerline.lib.monotonic import monotonic
+
+
+def default_cache_key(**kwargs):
+	return frozenset(kwargs.items())
+
+
+class memoize(object):
+	'''Memoization decorator with timeout.'''
+	def __init__(self, timeout, cache_key=default_cache_key, cache_reg_func=None):
+		self.timeout = timeout
+		self.cache_key = cache_key
+		self.cache = {}
+		self.cache_reg_func = cache_reg_func
+
+	def __call__(self, func):
+		@wraps(func)
+		def decorated_function(**kwargs):
+			if self.cache_reg_func:
+				self.cache_reg_func(self.cache)
+				self.cache_reg_func = None
+
+			key = self.cache_key(**kwargs)
+			try:
+				cached = self.cache.get(key, None)
+			except TypeError:
+				return func(**kwargs)
+			# Handle case when time() appears to be less then cached['time'] due 
+			# to clock updates. Not applicable for monotonic clock, but this 
+			# case is currently rare.
+			if cached is None or not (cached['time'] < monotonic() < cached['time'] + self.timeout):
+				cached = self.cache[key] = {
+					'result': func(**kwargs),
+					'time': monotonic(),
+				}
+			return cached['result']
+		return decorated_function