1 files changed, 53 insertions, 0 deletions
diff --git a/js/util.ts b/js/util.ts
new file mode 100644
index 000000000..70cb79a55
--- /dev/null
+++ b/js/util.ts
@@ -0,0 +1,53 @@
+// Copyright 2018 Ryan Dahl <ry@tinyclouds.org>
+// All rights reserved. MIT License.
+import { debug } from "./main";
+import { TypedArray } from "./types";
+
+// Internal logging for deno. Use the "debug" variable above to control
+// output.
+// tslint:disable-next-line:no-any
+export function log(...args: any[]): void {
+  if (debug) {
+    console.log(...args);
+  }
+}
+
+export function assert(cond: boolean, msg = "") {
+  if (!cond) {
+    throw Error(`Assert fail. ${msg}`);
+  }
+}
+
+export function typedArrayToArrayBuffer(ta: TypedArray): ArrayBuffer {
+  const ab = ta.buffer.slice(ta.byteOffset, ta.byteOffset + ta.byteLength);
+  return ab as ArrayBuffer;
+}
+
+export function arrayToStr(ui8: Uint8Array): string {
+  return String.fromCharCode(...ui8);
+}
+
+// A `Resolvable` is a Promise with the `reject` and `resolve` functions
+// placed as methods on the promise object itself. It allows you to do:
+//
+//   const p = createResolvable<number>();
+//   ...
+//   p.resolve(42);
+//
+// It'd be prettier to make Resolvable a class that inherits from Promise,
+// rather than an interface. This is possible in ES2016, however typescript
+// produces broken code when targeting ES5 code.
+// See https://github.com/Microsoft/TypeScript/issues/15202
+// At the time of writing, the github issue is closed but the problem remains.
+export interface Resolvable<T> extends Promise<T> {
+  resolve: (value?: T | PromiseLike<T>) => void;
+  // tslint:disable-next-line:no-any
+  reject: (reason?: any) => void;
+}
+export function createResolvable<T>(): Resolvable<T> {
+  let methods;
+  const promise = new Promise<T>((resolve, reject) => {
+    methods = { resolve, reject };
+  });
+  return Object.assign(promise, methods) as Resolvable<T>;
+}