Refactor: use TransformStream

Build/lib/text-decoder-stream.ts

@@ -0,0 +1,56 @@
+// Copyright 2016 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Polyfill for TextEncoderStream and TextDecoderStream
+
+// Modified by Sukka (https://skk.moe) to increase compatibility and performance with Bun.
+
+export class PolyfillTextDecoderStream extends TransformStream<Uint8Array, string> {
+  readonly encoding: string;
+  readonly fatal: boolean;
+  readonly ignoreBOM: boolean;
+
+  constructor(
+    encoding: Encoding = 'utf-8',
+    {
+      fatal = false,
+      ignoreBOM = false,
+    }: ConstructorParameters<typeof TextDecoder>[1] = {},
+  ) {
+    const decoder = new TextDecoder(encoding, { fatal, ignoreBOM });
+    super({
+      transform(chunk: Uint8Array, controller: TransformStreamDefaultController<string>) {
+        const decoded = decoder.decode(chunk);
+        if (decoded.length > 0) {
+          controller.enqueue(decoded);
+        }
+      },
+      flush(controller: TransformStreamDefaultController<string>) {
+        // If {fatal: false} is in options (the default), then the final call to
+        // decode() can produce extra output (usually the unicode replacement
+        // character 0xFFFD). When fatal is true, this call is just used for its
+        // side-effect of throwing a TypeError exception if the input is
+        // incomplete.
+        const output = decoder.decode();
+        if (output.length > 0) {
+          controller.enqueue(output);
+        }
+      }
+    });
+
+    this.encoding = encoding;
+    this.fatal = fatal;
+    this.ignoreBOM = ignoreBOM;
+  }
+}