1 files changed, 94 insertions, 0 deletions
diff --git a/js/dispatch_json.ts b/js/dispatch_json.ts
new file mode 100644
index 000000000..e8c976164
--- /dev/null
+++ b/js/dispatch_json.ts
@@ -0,0 +1,94 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+// Do not add flatbuffer dependencies to this module.
+// TODO(ry) Currently ErrorKind enum is defined in FlatBuffers. Therefore
+// we must still reference the msg_generated.ts. This should be removed!
+import { ErrorKind } from "gen/cli/msg_generated";
+import * as util from "./util";
+import { TextEncoder, TextDecoder } from "./text_encoding";
+import { core } from "./core";
+import { DenoError } from "./errors";
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+type Ok = any;
+
+interface JsonError {
+  kind: ErrorKind;
+  message: string;
+}
+
+interface JsonResponse {
+  ok?: Ok;
+  err?: JsonError;
+  promiseId?: number; // only present in async mesasges.
+}
+
+const promiseTable = new Map<number, util.Resolvable<number>>();
+let _nextPromiseId = 1;
+
+function nextPromiseId(): number {
+  return _nextPromiseId++;
+}
+
+function decode(ui8: Uint8Array): JsonResponse {
+  const s = new TextDecoder().decode(ui8);
+  return JSON.parse(s) as JsonResponse;
+}
+
+function encode(args: object): Uint8Array {
+  const s = JSON.stringify(args);
+  return new TextEncoder().encode(s);
+}
+
+function toDenoError(err: JsonError): DenoError<ErrorKind> {
+  return new DenoError(err.kind, err.message);
+}
+
+export function asyncMsgFromRust(opId: number, res: Uint8Array): void {
+  const { ok, err, promiseId } = decode(res);
+  const promise = promiseTable.get(promiseId!)!;
+  if (!promise) {
+    throw Error(`Async op ${opId} had bad promiseId`);
+  }
+  promiseTable.delete(promiseId!);
+
+  if (err) {
+    promise.reject(toDenoError(err));
+  } else if (ok) {
+    promise.resolve(ok);
+  } else {
+    util.unreachable();
+  }
+}
+
+export function sendSync(
+  opId: number,
+  args: object = {},
+  zeroCopy?: Uint8Array
+): Ok {
+  const argsUi8 = encode(args);
+  const res = core.dispatch(opId, argsUi8, zeroCopy);
+  if (!res) {
+    return;
+  }
+  const { ok, err, promiseId } = decode(res);
+  util.assert(!promiseId);
+  if (err) {
+    throw toDenoError(err);
+  }
+  return ok;
+}
+
+export function sendAsync(
+  opId: number,
+  args: object = {},
+  zeroCopy?: Uint8Array
+): Promise<Ok> {
+  const promiseId = nextPromiseId();
+  args = Object.assign(args, { promiseId });
+  const argsUi8 = encode(args);
+  const promise = util.createResolvable<Ok>();
+  promiseTable.set(promiseId, promise);
+  const r = core.dispatch(opId, argsUi8, zeroCopy);
+  util.assert(!r);
+  return promise;
+}