Make QuickLRU a Map subclass (sindresorhus#37)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>
titanism · Feb 18, 2022 · 2dd5b52 · 2dd5b52
1 parent cf1bbcf
commit 2dd5b52
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Showing 4 changed files with 94 additions and 2 deletions.
diff --git a/index.d.ts b/index.d.ts
@@ -24,7 +24,7 @@ export interface Options<KeyType, ValueType> {
 	onEviction?: (key: KeyType, value: ValueType) => void;
 }
 
-export default class QuickLRU<KeyType, ValueType> implements Iterable<[KeyType, ValueType]> {
+export default class QuickLRU<KeyType, ValueType> extends Map implements Iterable<[KeyType, ValueType]> {
 	/**
 	The stored item count.
 	*/

diff --git a/index.js b/index.js
@@ -1,5 +1,7 @@
-export default class QuickLRU {
+export default class QuickLRU extends Map {
 	constructor(options = {}) {
+		super();
+
 		if (!(options.maxSize && options.maxSize > 0)) {
 			throw new TypeError('`maxSize` must be a number greater than 0');
 		}
@@ -262,4 +264,18 @@ export default class QuickLRU {
 
 		return Math.min(this._size + oldCacheSize, this.maxSize);
 	}
+
+	entries() {
+		return this.entriesAscending();
+	}
+
+	forEach(callbackFunction, thisArgument = this) {
+		for (const [key, value] of this.entriesAscending()) {
+			callbackFunction.call(thisArgument, value, key, this);
+		}
+	}
+
+	[Symbol.toStringTag]() {
+		return JSON.stringify([...this.entriesAscending()]);
+	}
 }
diff --git a/readme.md b/readme.md
@@ -34,6 +34,8 @@ lru.get('🦄');
 
 Returns a new instance.
 
+It's a [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) subclass.
+
 ### options
 
 Type: `object`
@@ -122,6 +124,18 @@ Iterable for all entries, starting with the oldest (ascending in recency).
 
 Iterable for all entries, starting with the newest (descending in recency).
 
+#### .entries()
+
+Iterable for all entries, starting with the newest (ascending in recency).
+
+**This method exists for `Map` compatibility. Prefer [.entriesAscending()](#entriesascending) instead.**
+
+#### .forEach(callbackFunction, thisArgument)
+
+Loop over entries calling the `callbackFunction` for each entry (ascending in recency).
+
+**This method exists for `Map` compatibility. Prefer [.entriesAscending()](#entriesascending) instead.**
+
 #### .size
 
 The stored item count.

diff --git a/test.js b/test.js
@@ -577,6 +577,35 @@ test('max age - `entriesAscending()` should return the entries that are not expi
 	t.deepEqual([...lru.entriesAscending()], [['3', 'test3'], ['4', 'coco'], ['5', 'loco']]);
 });
 
+test('max age - `entries()` should return the entries that are not expired', async t => {
+	const lru = new QuickLRU({maxSize: 10, maxAge: 100});
+	lru.set('1', undefined);
+	lru.set('2', 'test2');
+	await delay(200);
+	lru.set('3', 'test3');
+	lru.set('4', 'coco');
+	lru.set('5', 'loco');
+
+	t.deepEqual([...lru.entries()], [['3', 'test3'], ['4', 'coco'], ['5', 'loco']]);
+});
+
+test('max age - `forEach()` should not return expired entries', async t => {
+	const lru = new QuickLRU({maxSize: 5, maxAge: 100});
+	lru.set('1', undefined);
+	lru.set('2', 'test2');
+	lru.set('3', 'test3');
+	await delay(200);
+	lru.set('4', 'coco');
+	lru.set('5', 'loco');
+	const entries = [];
+
+	lru.forEach((value, key) => {
+		entries.push([key, value]);
+	});
+
+	t.deepEqual(entries, [['4', 'coco'], ['5', 'loco']]);
+});
+
 test('max age - `.[Symbol.iterator]()` should not return expired items', async t => {
 	const lru = new QuickLRU({maxSize: 2, maxAge: 100});
 	lru.set('key', 'value');
@@ -617,6 +646,32 @@ test('entriesDescending enumerates cache items newest-first', t => {
 	t.deepEqual([...lru.entriesDescending()], [['v', 3], ['t', 4], ['a', 8], ['q', 2]]);
 });
 
+test('entries enumerates cache items oldest-first', t => {
+	const lru = new QuickLRU({maxSize: 3});
+	lru.set('1', 1);
+	lru.set('2', 2);
+	lru.set('3', 3);
+	lru.set('3', 7);
+	lru.set('2', 8);
+	t.deepEqual([...lru.entries()], [['1', 1], ['3', 7], ['2', 8]]);
+});
+
+test('forEach calls the cb function for each cache item oldest-first', t => {
+	const lru = new QuickLRU({maxSize: 3});
+	lru.set('1', 1);
+	lru.set('2', 2);
+	lru.set('3', 3);
+	lru.set('3', 7);
+	lru.set('2', 8);
+	const entries = [];
+
+	lru.forEach((value, key) => {
+		entries.push([key, value]);
+	});
+
+	t.deepEqual(entries, [['1', 1], ['3', 7], ['2', 8]]);
+});
+
 test('resize removes older items', t => {
 	const lru = new QuickLRU({maxSize: 2});
 	lru.set('1', 1);
@@ -685,3 +740,10 @@ test('function value', t => {
 	lru.get('fn')();
 	t.true(isCalled);
 });
+
+test('[Symbol.toStringTag] converts the cache items to a string in ascending order', t => {
+	const lru = new QuickLRU({maxSize: 2});
+	lru.set('1', 1);
+	lru.set('2', 2);
+	t.is(lru[Symbol.toStringTag](), '[["1",1],["2",2]]');
+});