feat: Add WritableStreams (and enable ReadableStreams piping) (#4980)

1 files changed, 68 insertions, 0 deletions

diff --git a/cli/js/web/streams/writable_stream_default_controller.ts b/cli/js/web/streams/writable_stream_default_controller.ts
new file mode 100644
index 000000000..040d0eefc
--- /dev/null
+++ b/cli/js/web/streams/writable_stream_default_controller.ts
@@ -0,0 +1,68 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+import {
+  AbortAlgorithm,
+  CloseAlgorithm,
+  isWritableStreamDefaultController,
+  Pair,
+  resetQueue,
+  setFunctionName,
+  SizeAlgorithm,
+  WriteAlgorithm,
+  writableStreamDefaultControllerClearAlgorithms,
+  writableStreamDefaultControllerError,
+} from "./internals.ts";
+import * as sym from "./symbols.ts";
+import { WritableStreamImpl } from "./writable_stream.ts";
+import { customInspect } from "../console.ts";
+
+export class WritableStreamDefaultControllerImpl<W>
+  implements WritableStreamDefaultController {
+  [sym.abortAlgorithm]: AbortAlgorithm;
+  [sym.closeAlgorithm]: CloseAlgorithm;
+  [sym.controlledWritableStream]: WritableStreamImpl;
+  [sym.queue]: Array<Pair<{ chunk: W } | "close">>;
+  [sym.queueTotalSize]: number;
+  [sym.started]: boolean;
+  [sym.strategyHWM]: number;
+  [sym.strategySizeAlgorithm]: SizeAlgorithm<W>;
+  [sym.writeAlgorithm]: WriteAlgorithm<W>;
+
+  private constructor() {
+    throw new TypeError(
+      "WritableStreamDefaultController's constructor cannot be called."
+    );
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  error(e: any): void {
+    if (!isWritableStreamDefaultController(this)) {
+      throw new TypeError("Invalid WritableStreamDefaultController.");
+    }
+    const state = this[sym.controlledWritableStream][sym.state];
+    if (state !== "writable") {
+      return;
+    }
+    writableStreamDefaultControllerError(this, e);
+  }
+
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  [sym.abortSteps](reason: any): PromiseLike<void> {
+    const result = this[sym.abortAlgorithm](reason);
+    writableStreamDefaultControllerClearAlgorithms(this);
+    return result;
+  }
+
+  [sym.errorSteps](): void {
+    resetQueue(this);
+  }
+
+  [customInspect](): string {
+    return `${this.constructor.name} { }`;
+  }
+}
+
+setFunctionName(
+  WritableStreamDefaultControllerImpl,
+  "WritableStreamDefaultController"
+);