feat: lru-cache driver (#146)

README.md

@@ -360,6 +360,21 @@ const storage = createStorage({
 });
 ```
 
+### `lru-cache` (universal)
+
+Keeps cached data in memory using [LRU Cache](https://www.npmjs.com/package/lru-cache).
+
+See [`lru-cache`](https://www.npmjs.com/package/lru-cache) for supported options. By default `{ maxSize: 500 }` is used.
+
+```js
+import { createStorage } from "unstorage";
+import lruCacheDriver from "unstorage/drivers/lru-cache";
+
+const storage = createStorage({
+  driver: lruCacheDriver(),
+});
+```
+
 ### `overlay` (universal)
 
 This is a special driver that creates a multi-layer overlay driver.

package.json

@@ -46,6 +46,7 @@
     "h3": "^1.1.0",
     "ioredis": "^5.3.0",
     "listhen": "^1.0.2",
+    "lru-cache": "^7.14.1",
     "mkdir": "^0.0.2",
     "mri": "^1.2.0",
     "node-fetch-native": "^1.0.1",

src/drivers/lru-cache.ts

@@ -0,0 +1,42 @@
+import { defineDriver } from "./utils";
+import LRU, { SharedOptions as _LRUOptions } from "lru-cache";
+
+type LRUOptions = _LRUOptions<string, any>;
+export interface LRUDriverOptions extends LRUOptions {}
+
+export default defineDriver((opts: LRUDriverOptions) => {
+  const cache = new LRU({
+    ...opts,
+    maxSize: 500,
+  });
+
+  return {
+    hasItem(key) {
+      return cache.has(key);
+    },
+    getItem(key) {
+      return cache.get(key) || null;
+    },
+    getItemRaw(key) {
+      return cache.get(key) || null;
+    },
+    setItem(key, value) {
+      cache.set(key, value);
+    },
+    setItemRaw(key, value) {
+      cache.set(key, value);
+    },
+    removeItem(key) {
+      cache.delete(key);
+    },
+    getKeys() {
+      return Array.from(cache.keys());
+    },
+    clear() {
+      cache.clear();
+    },
+    dispose() {
+      cache.clear();
+    },
+  };
+});

src/index.ts

@@ -12,6 +12,7 @@ export const builtinDrivers = {
   github: "unstorage/drivers/github",
   http: "unstorage/drivers/http",
   localStorage: "unstorage/drivers/localstorage",
+  lruCache: "unstorage/drivers/lru-cache",
   localstorage: "unstorage/drivers/localstorage",
   memory: "unstorage/drivers/memory",
   overlay: "unstorage/drivers/overlay",