fix: update EphemeralStore to support generic types (#718)

* fix: update EphemeralStore to support generic types

* fix: add delete for ephemeral

Author: Leeeon233

crates/loro-wasm/index.ts

@@ -249,8 +249,8 @@ export class Awareness<T extends Value = Value> {
  * store2.apply(encoded);
  * ```
  */
-export class EphemeralStore<T extends Value = Value> {
-    inner: EphemeralStoreWasm<T>;
+export class EphemeralStore<T extends Record<string, Value> = Record<string, Value>> {
+    inner: EphemeralStoreWasm;
     private timer: number | undefined;
     private timeout: number;
     constructor(timeout: number = 30000) {
@@ -263,21 +263,25 @@ export class EphemeralStore<T extends Value = Value> {
         this.startTimerIfNotEmpty();
     }
 
-    set(key: string, value: T) {
-        this.inner.set(key, value);
+    set<K extends keyof T>(key: K, value: T[K]) {
+        this.inner.set(key as string, value);
         this.startTimerIfNotEmpty();
     }
 
-    get(key: string): T | undefined {
-        return this.inner.get(key);
+    delete<K extends keyof T>(key: K) {
+        this.inner.delete(key as string);
     }
 
-    getAllStates(): Record<string, T> {
+    get<K extends keyof T>(key: K): T[K] | undefined {
+        return this.inner.get(key as string);
+    }
+
+    getAllStates(): Partial<T> {
         return this.inner.getAllStates();
     }
 
-    encode(key: string): Uint8Array {
-        return this.inner.encode(key);
+    encode<K extends keyof T>(key: K): Uint8Array {
+        return this.inner.encode(key as string);
     }
 
     encodeAll(): Uint8Array {

crates/loro-wasm/tests/ephemeral.test.ts

@@ -116,6 +116,31 @@ describe("EphemeralStore", () => {
         });
     });
 
+    it("generic type", () => {
+        // Define a type to test type inference
+        const store = new EphemeralStore<{ foo: string, bar: number }>(10);
+        // This should compile correctly
+        store.set("foo", "bar");
+        store.set("bar", 1);
+
+        // Verify runtime values are correct
+        expect(store.get("foo")).toBe("bar");
+        expect(store.get("bar")).toBe(1);
+
+        // Type inference for get should work too
+        const foo: string | undefined = store.get("foo");
+        const bar: number | undefined = store.get("bar");
+        expect(foo).toBe("bar");
+        expect(bar).toBe(1);
+
+        // @ts-expect-error - This should fail type checking as "foo" expects string
+        store.set("foo", 123);
+        // @ts-expect-error - This should fail type checking as "bar" expects number
+        store.set("bar", "string");
+        // @ts-expect-error - This should fail type checking as "baz" is not in the type
+        store.set("baz", "value");
+    });
+
     it("subscribe", () => {
         const store = new EphemeralStore(10);
         let callTimes = 0;