handle derivation from multiple signals

src/reactivity/utils/Subscriptions.ts

@@ -3,7 +3,7 @@ import { Subscriber, _Signal } from "../types";
 
 export class Subscriptions {
   private currentSubscriber: Subscriber | null = null;
-  private ancestors = new Map<_Signal<any>, _Signal<any>>();
+  private ancestors = new MapSet<_Signal<any>, _Signal<any>>();
   private subscriptions = new MapSet<_Signal<any>, Subscriber>();
 
   run(subscriber: Subscriber, fn: () => void): void {
@@ -22,10 +22,12 @@ export class Subscriptions {
     }
 
     if (subscriber.derived) {
-      this.ancestors.set(subscriber.derived, signal);
+      this.ancestors.addTo(subscriber.derived, signal);
     }
 
-    this.subscriptions.addTo(this._getAncestor(signal), subscriber);
+    this._getAncestors(signal).forEach((ancestor) => {
+      this.subscriptions.addTo(ancestor, subscriber);
+    });
   }
 
   executeAllSubscriptionsTo(signal: _Signal<any>) {
@@ -35,12 +37,12 @@ export class Subscriptions {
       .forEach((subscriber) => subscriber.execute());
   }
 
-  private _getAncestor(signal: _Signal<any>): _Signal<any> {
-    const ancestor = this.ancestors.get(signal);
-    if (!ancestor) {
-      return signal;
+  private _getAncestors(signal: _Signal<any>): _Signal<any>[] {
+    const ancestors = this.ancestors.get(signal);
+    if (!ancestors || ancestors.length === 0) {
+      return [signal];
     }
 
-    return this._getAncestor(ancestor);
+    return ancestors.flatMap((ancestor) => this._getAncestors(ancestor));
   }
 }

test/reactivity.test.ts

@@ -188,4 +188,50 @@ describe("reactivity", () => {
       "14px 14pt",
     ]);
   });
+
+  it("derive from multiple signals", () => {
+    const calls: string[] = [];
+    const [count, setCount] = signal(1);
+    const [name, setName] = signal("First");
+    const nameAndCount = d`${name} -> ${count}`
+
+    effect(() => calls.push(nameAndCount()));
+
+    setCount(5);
+    setName("Second");
+    setName("Third");
+    setCount(7);
+
+    expect(calls).toEqual([
+      "First -> 1",
+      "First -> 5",
+      "Second -> 5",
+      "Third -> 5",
+      "Third -> 7",
+    ]);
+  });
+
+  it("derive from multiple signals and other derivations", () => {
+    const calls: string[] = [];
+    const [count, setCount] = signal(1);
+    const [name, setName] = signal("First");
+    const nameAndCount = d`${name} -> ${count}`
+    const sum = derive(0, () => count() + count())
+    const sumText = d`${nameAndCount} + ${count} = ${sum}`
+
+    effect(() => calls.push(sumText()));
+
+    setCount(5);
+    setName("Second");
+    setName("Third");
+    setCount(7);
+
+    expect(calls).toEqual([
+      "First -> 1 + 1 = 2",
+      "First -> 5 + 5 = 10",
+      "Second -> 5 + 5 = 10",
+      "Third -> 5 + 5 = 10",
+      "Third -> 7 + 7 = 14",
+    ]);
+  });
 });

vite.config.ts

@@ -6,7 +6,7 @@ export default defineConfig({
     environment: "jsdom",
     coverage: {
       reporter: ["text", "html"],
-      exclude: [ "index.ts", "examples/**" ],
+      exclude: [ "index.ts", "examples/**", "cdn/**" ],
     },
   }
 });