add polyfill

Author: neverRare

build/dev.ts

@@ -3,6 +3,7 @@
 import { assert } from "@std/assert/assert";
 import { exists } from "@std/fs/exists";
 import { BuildOptions, context } from "esbuild";
+import { AsyncDisposableStack } from "../misc/async_disposable_stack.ts";
 import { OPTIONS } from "./config.ts";
 
 const BUILD_OPTIONS: BuildOptions = {

dictionary/watch.ts

@@ -2,6 +2,7 @@
 
 import { unreachable } from "@std/assert/unreachable";
 import { debounce } from "@std/async/debounce";
+import { AsyncDisposableStack } from "../misc/async_disposable_stack.ts";
 import { build } from "./build.ts";
 
 async function tryBuild(): Promise<void> {

misc/async_disposable_stack.ts

@@ -0,0 +1,33 @@
+// This code is Deno only
+
+// TODO: remove this after Deno supports it
+export class AsyncDisposableStack implements AsyncDisposable {
+  #callbacks: Array<() => Promise<void>> = [];
+  defer(onDisposeAsync: () => Promise<void>): void {
+    this.#callbacks.push(onDisposeAsync);
+  }
+  move(): AsyncDisposableStack {
+    const newStack = new AsyncDisposableStack();
+    newStack.#callbacks = this.#callbacks;
+    this.#callbacks = [];
+    return newStack;
+  }
+  async [Symbol.asyncDispose](): Promise<void> {
+    const errors = [];
+    for (const callback of this.#callbacks.reverse()) {
+      try {
+        await callback();
+      } catch (error) {
+        errors.push(error);
+      }
+    }
+    switch (errors.length) {
+      case 0:
+        break;
+      case 1:
+        throw errors[0];
+      default:
+        throw AggregateError(errors);
+    }
+  }
+}