From 0db3edc3e87c29073ece739b97af6d0618ff226d Mon Sep 17 00:00:00 2001
From: Rich Harris <rich.harris@vercel.com>
Date: Tue, 28 Nov 2023 20:17:23 -0500
Subject: [PATCH] eliminate closures

---
 packages/svelte/src/internal/client/magic.js | 173 +++++++++++--------
 1 file changed, 99 insertions(+), 74 deletions(-)

diff --git a/packages/svelte/src/internal/client/magic.js b/packages/svelte/src/internal/client/magic.js
index 814eaf9c1a..11dc82af49 100644
--- a/packages/svelte/src/internal/client/magic.js
+++ b/packages/svelte/src/internal/client/magic.js
@@ -1,107 +1,132 @@
 import { effect_active, get, set, increment, source } from './runtime.js';
 
+/** @typedef {{ p: MagicObject | null; s: Map<string | symbol, import('./types').SourceSignal<any>>; v: import('./types').SourceSignal<number>; a: boolean }} Magic */
+/** @typedef {Record<string | symbol, any> & { [MAGIC_SYMBOL]: Magic }} MagicObject */
+
 export const MAGIC_SYMBOL = Symbol();
 export const MAGIC_EACH_SYMBOL = Symbol();
 
 /**
- * @template T
+ * @template {MagicObject} T
  * @param {T} value
  * @returns {T}
  */
 export function magic(value) {
-	if (value && typeof value === 'object') {
-		return wrap(value, null);
-	}
-
-	return value;
+	return wrap(value, null);
 }
 
 /**
- * @template T
+ * @template {MagicObject} T
+ * @template {MagicObject} P
  * @param {T} value
- * @param {T | null} parent
+ * @param {P | null} parent
  * @returns {T}
  */
 function wrap(value, parent) {
 	if (value && typeof value === 'object') {
-		return object(value, parent);
+		return proxy(value, parent);
 	}
 
 	return value;
 }
 
+/** @type {ProxyHandler<MagicObject>} */
+const handler = {
+	get(target, prop, receiver) {
+		if (prop === MAGIC_EACH_SYMBOL) {
+			return parent;
+		}
+
+		const metadata = target[MAGIC_SYMBOL];
+		let s = metadata.s.get(prop);
+
+		if (s === undefined && effect_active()) {
+			s = source(wrap(target[prop], receiver));
+			metadata.s.set(prop, s);
+		}
+
+		const value = s !== undefined ? get(s) : target[prop];
+
+		if (typeof value === 'function') {
+			// @ts-ignore
+			return (...args) => {
+				return value.apply(receiver, args);
+			};
+		}
+		return value;
+	},
+	set(target, prop, value) {
+		const metadata = target[MAGIC_SYMBOL];
+
+		const s = metadata.s.get(prop);
+		if (s !== undefined) set(s, wrap(value, target));
+
+		if (metadata.a && prop === 'length') {
+			for (let i = value; i < target.length; i += 1) {
+				const s = metadata.s.get(i + '');
+				if (s !== undefined) set(s, undefined);
+			}
+		}
+
+		if (!(prop in target)) increment(metadata.v);
+		// @ts-ignore
+		target[prop] = value;
+
+		return true;
+	},
+	deleteProperty(target, prop) {
+		const metadata = target[MAGIC_SYMBOL];
+
+		const s = metadata.s.get(prop);
+		if (s !== undefined) set(s, undefined);
+
+		if (prop in target) increment(metadata.v);
+
+		return delete target[prop];
+	},
+	has(target, prop) {
+		if (prop === MAGIC_SYMBOL) return true;
+
+		const metadata = target[MAGIC_SYMBOL];
+
+		get(metadata.v);
+		return Reflect.has(target, prop);
+	},
+	ownKeys(target) {
+		const metadata = target[MAGIC_SYMBOL];
+
+		get(metadata.v);
+		return Reflect.ownKeys(target);
+	}
+};
+
 /**
- * @template {Record<string | symbol, any>} T
- * @template P
+ * @template {MagicObject} T
+ * @template {MagicObject} P
  * @param {T} value
  * @param {P | null} parent
  * @returns {T}
  */
-function object(value, parent) {
+function proxy(value, parent) {
 	if (MAGIC_SYMBOL in value) return value;
 
-	/** @type {Map<string | symbol, any>} */
-	const sources = new Map();
-	let version = source(0);
-
-	const is_array = Array.isArray(value);
+	// @ts-expect-error
+	value[MAGIC_SYMBOL] = init(value, parent);
 
-	return new Proxy(value, {
-		get(target, prop, receiver) {
-			if (prop === MAGIC_EACH_SYMBOL) {
-				return parent;
-			}
-			let s = sources.get(prop);
-
-			if (s === undefined && effect_active()) {
-				s = source(wrap(target[prop], receiver));
-				sources.set(prop, s);
-			}
-
-			const value = s !== undefined ? get(s) : target[prop];
-
-			if (typeof value === 'function') {
-				// @ts-ignore
-				return (...args) => {
-					return value.apply(receiver, args);
-				};
-			}
-			return value;
-		},
-		set(target, prop, value) {
-			const s = sources.get(prop);
-			if (s !== undefined) set(s, wrap(value, target));
-
-			if (is_array && prop === 'length') {
-				for (let i = value; i < target.length; i += 1) {
-					const s = sources.get(i + '');
-					if (s !== undefined) set(s, undefined);
-				}
-			}
+	// @ts-expect-error not sure how to fix this
+	return new Proxy(value, handler);
+}
 
-			if (!(prop in target)) increment(version);
-			// @ts-ignore
-			target[prop] = value;
-
-			return true;
-		},
-		deleteProperty(target, prop) {
-			const s = sources.get(prop);
-			if (s !== undefined) set(s, undefined);
-
-			if (prop in target) increment(version);
-
-			return delete target[prop];
-		},
-		has(target, prop) {
-			if (prop === MAGIC_SYMBOL) return true;
-
-			get(version);
-			return Reflect.has(target, prop);
-		},
-		ownKeys(target) {
-			get(version);
-			return Reflect.ownKeys(target);
-		}
-	});
+/**
+ * @param {MagicObject} value
+ * @param {MagicObject | null} parent
+ * @returns {Magic}
+ */
+function init(value, parent) {
+	return {
+		p: parent,
+		s: new Map(),
+		v: source(0),
+		a: Array.isArray(value)
+	};
 }