fix: more fine-grained SvelteSet and SvelteMap

.changeset/khaki-ravens-carry.md

@@ -0,0 +1,5 @@
+---
+'svelte': patch
+---
+
+fix: more fine-grained SvelteSet and SvelteMap

packages/svelte/src/reactivity/map.js

@@ -56,6 +56,7 @@ export class SvelteMap extends Map {
 	#version = state(0);
 	#size = state(0);
 	#update_version = update_version || -1;
+	#fully_trackable = true;
 
 	/**
 	 * @param {Iterable<readonly [K, V]> | null | undefined} [value]
@@ -75,7 +76,11 @@ export class SvelteMap extends Map {
 			for (var [key, v] of value) {
 				super.set(key, v);
 			}
-			this.#size.v = super.size;
+			var size = super.size;
+			this.#size.v = size;
+			if (size > 0) {
+				this.#fully_trackable = false;
+			}
 		}
 	}
 
@@ -96,27 +101,19 @@ export class SvelteMap extends Map {
 	has(key) {
 		var sources = this.#sources;
 		var s = sources.get(key);
+		var has = super.has(key);
 
 		if (s === undefined) {
-			var ret = super.get(key);
-			if (ret !== undefined) {
-				s = this.#source(0);
-
-				if (DEV) {
-					tag(s, `SvelteMap get(${label(key)})`);
-				}
+			s = this.#source(has ? 0 : -1);
+			sources.set(key, s);
 
-				sources.set(key, s);
-			} else {
-				// We should always track the version in case
-				// the Set ever gets this value in the future.
-				get(this.#version);
-				return false;
+			if (DEV) {
+				tag(s, `SvelteMap get(${label(key)})`);
 			}
 		}
-
 		get(s);
-		return true;
+
+		return has;
 	}
 
 	/**
@@ -134,24 +131,15 @@ export class SvelteMap extends Map {
 		var s = sources.get(key);
 
 		if (s === undefined) {
-			var ret = super.get(key);
-			if (ret !== undefined) {
-				s = this.#source(0);
-
-				if (DEV) {
-					tag(s, `SvelteMap get(${label(key)})`);
-				}
+			s = this.#source(super.has(key) ? 0 : -1);
+			sources.set(key, s);
 
-				sources.set(key, s);
-			} else {
-				// We should always track the version in case
-				// the Set ever gets this value in the future.
-				get(this.#version);
-				return undefined;
+			if (DEV) {
+				tag(s, `SvelteMap get(${label(key)})`);
 			}
 		}
-
 		get(s);
+
 		return super.get(key);
 	}
 
@@ -176,6 +164,11 @@ export class SvelteMap extends Map {
 			sources.set(key, s);
 			set(this.#size, super.size);
 			increment(version);
+			// if it is a signal for non-existing value
+		} else if (s.v === -1) {
+			set(this.#size, super.size);
+			increment(s);
+			increment(version);
 		} else if (prev_res !== value) {
 			increment(s);
 
@@ -200,8 +193,7 @@ export class SvelteMap extends Map {
 		var s = sources.get(key);
 		var res = super.delete(key);
 
-		if (s !== undefined) {
-			sources.delete(key);
+		if (s !== undefined && s.v !== -1) {
 			set(this.#size, super.size);
 			set(s, -1);
 			increment(this.#version);
@@ -222,14 +214,13 @@ export class SvelteMap extends Map {
 			set(s, -1);
 		}
 		increment(this.#version);
-		sources.clear();
 	}
 
 	#read_all() {
 		get(this.#version);
 
 		var sources = this.#sources;
-		if (this.#size.v !== sources.size) {
+		if (!this.#fully_trackable) {
 			for (var key of super.keys()) {
 				if (!sources.has(key)) {
 					var s = this.#source(0);
@@ -240,10 +231,11 @@ export class SvelteMap extends Map {
 					sources.set(key, s);
 				}
 			}
+			this.#fully_trackable = true;
 		}
 
-		for ([, s] of this.#sources) {
-			get(s);
+		for ([, s] of sources) {
+			if (s.v !== -1) get(s);
 		}
 	}
 

packages/svelte/src/reactivity/map.test.ts

@@ -52,7 +52,6 @@ test('map.values()', () => {
 		false,
 		[1, 2, 4, 5],
 		0,
-		false,
 		[],
 		1,
 		true,
@@ -214,11 +213,11 @@ test('not invoking reactivity when value is not in the map after changes', () =>
 
 	const cleanup = effect_root(() => {
 		render_effect(() => {
-			log.push(map.get(1));
+			log.push('1', map.get(1));
 		});
 
 		render_effect(() => {
-			log.push(map.get(2));
+			log.push('2', map.get(2));
 		});
 
 		flushSync(() => {
@@ -230,7 +229,7 @@ test('not invoking reactivity when value is not in the map after changes', () =>
 		});
 	});
 
-	assert.deepEqual(log, [1, undefined, undefined, undefined, 1, undefined]);
+	assert.deepEqual(log, ['1', 1, '2', undefined, '1', undefined, '1', 1]);
 
 	cleanup();
 });

packages/svelte/src/reactivity/set.js

@@ -122,15 +122,7 @@ export class SvelteSet extends Set {
 		var s = sources.get(value);
 
 		if (s === undefined) {
-			if (!has) {
-				// If the value doesn't exist, track the version in case it's added later
-				// but don't create sources willy-nilly to track all possible values
-				get(this.#version);
-				return false;
-			}
-
-			s = this.#source(true);
-
+			s = this.#source(has);
 			if (DEV) {
 				tag(s, `SvelteSet has(${label(value)})`);
 			}
@@ -144,6 +136,12 @@ export class SvelteSet extends Set {
 
 	/** @param {T} value */
 	add(value) {
+		var s = this.#sources.get(value);
+
+		if (s?.v === false) {
+			set(s, true);
+		}
+
 		if (!super.has(value)) {
 			super.add(value);
 			set(this.#size, super.size);
@@ -160,7 +158,6 @@ export class SvelteSet extends Set {
 		var s = sources.get(value);
 
 		if (s !== undefined) {
-			sources.delete(value);
 			set(s, false);
 		}
 
@@ -178,13 +175,11 @@ export class SvelteSet extends Set {
 		}
 		// Clear first, so we get nice console.log outputs with $inspect
 		super.clear();
-		var sources = this.#sources;
 
-		for (var s of sources.values()) {
+		for (var s of this.#sources.values()) {
 			set(s, false);
 		}
 
-		sources.clear();
 		set(this.#size, 0);
 		increment(this.#version);
 	}

packages/svelte/src/reactivity/set.test.ts

@@ -30,7 +30,7 @@ test('set.values()', () => {
 		set.clear();
 	});
 
-	assert.deepEqual(log, [5, true, [1, 2, 3, 4, 5], 4, false, [1, 2, 4, 5], 0, false, []]);
+	assert.deepEqual(log, [5, true, [1, 2, 3, 4, 5], 4, false, [1, 2, 4, 5], 0, []]);
 
 	cleanup();
 });
@@ -143,12 +143,8 @@ test('not invoking reactivity when value is not in the set after changes', () =>
 		false,
 		'has 2',
 		false,
-		'has 3',
-		false,
 		'has 2',
-		true,
-		'has 3',
-		false
+		true
 	]);
 
 	cleanup();