Add TransformStream and TransformStreamController (#5042)

1 files changed, 75 insertions, 0 deletions

diff --git a/cli/js/web/streams/transform_stream_default_controller.ts b/cli/js/web/streams/transform_stream_default_controller.ts
new file mode 100644
index 000000000..2fc8d2160
--- /dev/null
+++ b/cli/js/web/streams/transform_stream_default_controller.ts
@@ -0,0 +1,75 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import {
+  FlushAlgorithm,
+  isTransformStreamDefaultController,
+  readableStreamDefaultControllerGetDesiredSize,
+  setFunctionName,
+  TransformAlgorithm,
+  transformStreamDefaultControllerEnqueue,
+  transformStreamDefaultControllerError,
+  transformStreamDefaultControllerTerminate,
+} from "./internals.ts";
+import { ReadableStreamDefaultControllerImpl } from "./readable_stream_default_controller.ts";
+import * as sym from "./symbols.ts";
+import { TransformStreamImpl } from "./transform_stream.ts";
+import { customInspect } from "../console.ts";
+
+// eslint-disable-next-line @typescript-eslint/no-explicit-any
+export class TransformStreamDefaultControllerImpl<I = any, O = any>
+  implements TransformStreamDefaultController<O> {
+  [sym.controlledTransformStream]: TransformStreamImpl<I, O>;
+  [sym.flushAlgorithm]: FlushAlgorithm;
+  [sym.transformAlgorithm]: TransformAlgorithm<I>;
+
+  private constructor() {
+    throw new TypeError(
+      "TransformStreamDefaultController's constructor cannot be called."
+    );
+  }
+
+  get desiredSize(): number | null {
+    if (!isTransformStreamDefaultController(this)) {
+      throw new TypeError("Invalid TransformStreamDefaultController.");
+    }
+    const readableController = this[sym.controlledTransformStream][
+      sym.readable
+    ][sym.readableStreamController];
+    return readableStreamDefaultControllerGetDesiredSize(
+      readableController as ReadableStreamDefaultControllerImpl<O>
+    );
+  }
+
+  enqueue(chunk: O): void {
+    if (!isTransformStreamDefaultController(this)) {
+      throw new TypeError("Invalid TransformStreamDefaultController.");
+    }
+    transformStreamDefaultControllerEnqueue(this, chunk);
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  error(reason?: any): void {
+    if (!isTransformStreamDefaultController(this)) {
+      throw new TypeError("Invalid TransformStreamDefaultController.");
+    }
+    transformStreamDefaultControllerError(this, reason);
+  }
+
+  terminate(): void {
+    if (!isTransformStreamDefaultController(this)) {
+      throw new TypeError("Invalid TransformStreamDefaultController.");
+    }
+    transformStreamDefaultControllerTerminate(this);
+  }
+
+  [customInspect](): string {
+    return `${this.constructor.name} { desiredSize: ${String(
+      this.desiredSize
+    )} }`;
+  }
+}
+
+setFunctionName(
+  TransformStreamDefaultControllerImpl,
+  "TransformStreamDefaultController"
+);