Merge pull request #184 from m-ld/null-remotes

Add `NullRemotes`

package.json

@@ -13,6 +13,7 @@
     "./ext/socket.io-server": "./ext/socket.io/server/index.js",
     "./ext/socket.io/server": "./ext/socket.io/server/index.js",
     "./ext/ably": "./ext/ably/index.js",
+    "./ext/null": "./ext/null/index.js",
     "./ext/html": "./ext/html/index.js",
     "./ext/wrtc": "./ext/wrtc/index.js",
     "./ext/security": "./ext/security/index.js",

src/null/NullRemotes.ts

@@ -0,0 +1,32 @@
+import { BehaviorSubject, NEVER, type Observable } from "rxjs";
+
+import { MeldRemotes, OperationMessage, MeldLocal } from "../engine";
+import type { LiveValue } from '../engine/api-support';
+
+class NotImplementedError extends Error {
+  constructor(methodName: string) {
+    super(
+      `${methodName} is not implemented for a NullRemote. The local clone should be genesis.`
+    );
+  }
+}
+
+export class NullRemotes implements MeldRemotes {
+  readonly operations: Observable<OperationMessage> = NEVER;
+  readonly updates: Observable<OperationMessage> = NEVER;
+  readonly live: LiveValue<boolean | null> = new BehaviorSubject(false);
+
+  setLocal(_clone: MeldLocal | null): void {}
+
+  newClock(): never {
+    throw new NotImplementedError("newClock");
+  }
+
+  revupFrom(): never {
+    throw new NotImplementedError("revupFrom");
+  }
+
+  snapshot(): never {
+    throw new NotImplementedError("snapshot");
+  }
+}

src/null/index.ts

@@ -0,0 +1 @@
+export { NullRemotes } from './NullRemotes';