From a28ae6f7501e10a16e62e3efc1e5135a1228c6c0 Mon Sep 17 00:00:00 2001
From: Nathan Rajlich <n@n8.io>
Date: Mon, 30 Dec 2024 00:11:58 -0800
Subject: [PATCH] Remove `singleton()`, add `createSingleton()`

---
 .changeset/khaki-dogs-reflect.md |  5 ++++
 packages/ncm/src/types.ts        | 15 +++++++----
 packages/util/src/index.ts       | 45 +++++++++++++-------------------
 3 files changed, 33 insertions(+), 32 deletions(-)
 create mode 100644 .changeset/khaki-dogs-reflect.md

diff --git a/.changeset/khaki-dogs-reflect.md b/.changeset/khaki-dogs-reflect.md
new file mode 100644
index 00000000..01b9513e
--- /dev/null
+++ b/.changeset/khaki-dogs-reflect.md
@@ -0,0 +1,5 @@
+---
+"@nx.js/util": major
+---
+
+Remove `singleton()`, add `createSingleton()`
diff --git a/packages/ncm/src/types.ts b/packages/ncm/src/types.ts
index 6a9c0204..4ce0920d 100644
--- a/packages/ncm/src/types.ts
+++ b/packages/ncm/src/types.ts
@@ -1,7 +1,11 @@
-import { ArrayBufferStruct, singleton, u8, view } from '@nx.js/util';
+import { ArrayBufferStruct, createSingleton, u8, view } from '@nx.js/util';
 
-const contentIds = new WeakMap<ArrayBufferView, NcmContentId>();
-const contentMetaKeys = new WeakMap<ArrayBufferView, NcmContentMetaKey>();
+const contentIdCache = createSingleton(
+	(self: NcmContentInfo) => new NcmContentId(self, 0x0),
+);
+const contentMetaKeyCache = createSingleton(
+	(self: NcmContentStorageRecord) => new NcmContentMetaKey(self, 0x0),
+);
 
 /// StorageId
 export enum NcmStorageId {
@@ -93,6 +97,7 @@ export class NcmPlaceHolderId extends ArrayBufferStruct {
 	static sizeof = 0x10 as const;
 }
 
+/// ContentStorageRecord
 export class NcmContentStorageRecord extends ArrayBufferStruct {
 	//NcmContentMetaKey key;
 	//u8 storage_id;
@@ -100,7 +105,7 @@ export class NcmContentStorageRecord extends ArrayBufferStruct {
 	static sizeof = 0x18 as const;
 
 	get key() {
-		return singleton(contentMetaKeys, this, () => new NcmContentMetaKey(this));
+		return contentMetaKeyCache(this);
 	}
 	set key(v: NcmContentMetaKey) {
 		u8(this).set(u8(v), 0);
@@ -163,7 +168,7 @@ export class NcmContentInfo extends ArrayBufferStruct {
 	static sizeof = 0x18 as const;
 
 	get contentId() {
-		return singleton(contentIds, this, () => new NcmContentId(this));
+		return contentIdCache(this);
 	}
 	set contentId(v: NcmContentId) {
 		u8(this).set(u8(v), 0);
diff --git a/packages/util/src/index.ts b/packages/util/src/index.ts
index 75b9a2c4..205afcca 100644
--- a/packages/util/src/index.ts
+++ b/packages/util/src/index.ts
@@ -1,33 +1,24 @@
-export function singleton<K extends object, V>(
-	map: WeakMap<K, V>,
-	key: K,
-	init: () => V,
-) {
-	let value = map.get(key);
-	if (!value) {
-		value = init();
-		map.set(key, value);
-	}
-	return value;
+export function createSingleton<K extends object, V>(init: (k: K) => V) {
+	const map = new WeakMap<K, V>();
+	return (k: K) => {
+		if (!map.has(k)) {
+			const v = init(k);
+			map.set(k, v);
+			return v;
+		}
+		return map.get(k)!;
+	};
 }
 
-const views = new WeakMap<ArrayBufferView, DataView>();
-export function view(view: ArrayBufferView): DataView {
-	return singleton(
-		views,
-		view,
-		() => new DataView(view.buffer, view.byteOffset, view.byteLength),
-	);
-}
+export const view = createSingleton(
+	(view: ArrayBufferView) =>
+		new DataView(view.buffer, view.byteOffset, view.byteLength),
+);
 
-const u8s = new WeakMap<ArrayBufferView, Uint8Array>();
-export function u8(view: ArrayBufferView): Uint8Array {
-	return singleton(
-		u8s,
-		view,
-		() => new Uint8Array(view.buffer, view.byteOffset, view.byteLength),
-	);
-}
+export const u8 = createSingleton(
+	(view: ArrayBufferView) =>
+		new Uint8Array(view.buffer, view.byteOffset, view.byteLength),
+);
 
 export function decodeCString(view: ArrayBufferView): string {
 	const arr = u8(view);