TypeScript!

lib/common/memoize.ts

@@ -0,0 +1,43 @@
+let cache1 = new Map();
+let cache2 = new Map();
+const keys = new WeakMap();
+
+function getKey(obj): string {
+  if (obj === null) return "null";
+  else if (obj === undefined) return "undefined";
+
+  const t = typeof obj;
+  if (t === "number" || t === "boolean" || t === "string") return `${t}:${obj}`;
+  if (t !== "function" && t !== "object")
+    throw new Error(`Cannot memoize ${t} arguments`);
+
+  let k = keys.get(obj);
+  if (!k) {
+    const rnd = Math.trunc(Math.random() * Number.MAX_SAFE_INTEGER);
+    k = `${t}:${rnd.toString(36)}`;
+    keys.set(obj, k);
+  }
+  return k;
+}
+
+export default function memoize(func): Function {
+  return (...args) => {
+    const key = JSON.stringify(args.map(getKey)) + getKey(func);
+
+    if (cache1.has(key)) return cache1.get(key);
+
+    let r;
+    if (cache2.has(key)) r = cache2.get(key);
+    else r = func(...args);
+    cache1.set(key, r);
+    return r;
+  };
+}
+
+const interval = setInterval(() => {
+  cache2 = cache1;
+  cache1 = new Map();
+}, 120000);
+
+// Don't hold Node.js process
+if (interval.unref) interval.unref();