1 files changed, 107 insertions, 0 deletions
diff --git a/std/bundle/utils.ts b/std/bundle/utils.ts
new file mode 100644
index 000000000..91c0820bf
--- /dev/null
+++ b/std/bundle/utils.ts
@@ -0,0 +1,107 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+
+import { assert } from "../testing/asserts.ts";
+import { exists } from "../fs/exists.ts";
+
+export interface DefineFactory {
+  /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
+  (...args: any): object | void;
+}
+
+export interface ModuleMetaData {
+  dependencies: string[];
+  factory?: DefineFactory | object;
+  exports: object;
+}
+
+type Define = (
+  id: string,
+  dependencies: string[],
+  factory: DefineFactory
+) => void;
+
+/* eslint-disable @typescript-eslint/no-namespace */
+declare global {
+  namespace globalThis {
+    // eslint-disable-next-line no-var
+    var define: Define | undefined;
+  }
+}
+/* eslint-enable @typescript-eslint/no-namespace */
+
+/** Evaluate the bundle, returning a queue of module IDs and their data to
+ * instantiate.
+ */
+export function evaluate(
+  text: string
+): [string[], Map<string, ModuleMetaData>] {
+  const queue: string[] = [];
+  const modules = new Map<string, ModuleMetaData>();
+
+  globalThis.define = function define(
+    id: string,
+    dependencies: string[],
+    factory: DefineFactory
+  ): void {
+    modules.set(id, {
+      dependencies,
+      factory,
+      exports: {}
+    });
+    queue.push(id);
+  };
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  (Deno as any).core.evalContext(text);
+  // Deleting `define()` so it isn't accidentally there when the modules
+  // instantiate.
+  delete globalThis.define;
+
+  return [queue, modules];
+}
+
+/** Drain the queue of module IDs while instantiating the modules. */
+export function instantiate(
+  queue: string[],
+  modules: Map<string, ModuleMetaData>
+): void {
+  let id: string | undefined;
+  while ((id = queue.shift())) {
+    const module = modules.get(id)!;
+    assert(module != null);
+    assert(module.factory != null);
+
+    const dependencies = module.dependencies.map((id): object => {
+      if (id === "require") {
+        // TODO(kitsonk) support dynamic import by passing a `require()` that
+        // can return a local module or dynamically import one.
+        return (): void => {};
+      } else if (id === "exports") {
+        return module.exports;
+      }
+      const dep = modules.get(id)!;
+      assert(dep != null);
+      return dep.exports;
+    });
+
+    if (typeof module.factory === "function") {
+      module.factory!(...dependencies);
+    } else if (module.factory) {
+      // when bundling JSON, TypeScript just emits it as an object/array as the
+      // third argument of the `define()`.
+      module.exports = module.factory;
+    }
+    delete module.factory;
+  }
+}
+
+/** Load the bundle and return the contents asynchronously. */
+export async function load(args: string[]): Promise<string> {
+  // TODO(kitsonk) allow loading of remote bundles via fetch.
+  assert(args.length >= 2, "Expected at least two arguments.");
+  const [, bundleFileName] = args;
+  assert(
+    await exists(bundleFileName),
+    `Expected "${bundleFileName}" to exist.`
+  );
+  return new TextDecoder().decode(await Deno.readFile(bundleFileName));
+}