Created
March 10, 2010 13:11
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(defn- stateful-memoize | |
[f #^java.util.Map map] | |
(fn [& args] | |
(if-let [e (find map args)] | |
(val e) | |
(let [ret (apply f args)] | |
(.put map args ret) | |
ret)))) | |
(defn weak-memoize | |
"Same as memoize, but uses a WeakHashMap for storing argument keys and result values. | |
**Be aware of what this entails for persistence of values: lose your keys, and | |
the associated value may get recalculated**" | |
[f] | |
(stateful-memoize f (java.util.WeakHashMap.))) | |
(defn lru-map | |
[max-size] | |
(proxy [java.util.LinkedHashMap] [] | |
(removeEldestEntry [entry] | |
(> (.size #^java.util.Map this) max-size)))) | |
(defn lru-memoize | |
"Same as memoize, but uses a LinkedHashMap-based LRU cache to ensure that a maximum of | |
max-size entries are held at any time." | |
[f max-size] | |
(stateful-memoize f (lru-map max-size))) |
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