Improve folder structure

examples/preact/ops.js

@@ -0,0 +1,64 @@
+/*
+ * Copyright 2021 Google LLC
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+import initModule from './build/libapi.mjs';
+
+/** @typedef {import('../libapi.mjs').Context} Context */
+
+const ModulePromise = initModule();
+
+export function rethrowIfCritical(err) {
+  // If it's precisely Error, it's a custom error; anything else - SyntaxError,
+  // WebAssembly.RuntimeError, TypeError, etc. - is treated as critical here.
+  if (err.constructor !== Error)
+  {
+    throw err;
+  }
+}
+
+export async function connect() {
+  const Module = await ModulePromise;
+
+  let context = await new Module.Context();
+  let supportedOps = await context.supportedOps();
+
+  /** @type {Promise<unknown>} */
+  let queue = Promise.resolve();
+
+  /** Schedules an exclusive async operation on the global context.
+   * @template T
+   * @param {(ctx: Context) => Promise<T>} op
+   * @returns {Promise<T>}
+   */
+  function schedule(op)
+  {
+    let res = queue.then(() => op(context));
+    queue = res.catch(rethrowIfCritical);
+    return res;
+  }
+
+  return {
+    supportedOps,
+    schedule,
+    disconnect() {
+      context.delete();
+    }
+  };
+}
+
+/** @typedef {ReturnType<typeof connect> extends Promise<infer Connection> ? Connection : never} Connection */