1 files changed, 106 insertions, 0 deletions
diff --git a/src/js/builtins/TransformStream.ts b/src/js/builtins/TransformStream.ts
new file mode 100644
index 000000000..54467db39
--- /dev/null
+++ b/src/js/builtins/TransformStream.ts
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2020 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+export function initializeTransformStream(this) {
+  let transformer = arguments[0];
+
+  // This is the path for CreateTransformStream.
+  if ($isObject(transformer) && $getByIdDirectPrivate(transformer, "TransformStream")) return this;
+
+  let writableStrategy = arguments[1];
+  let readableStrategy = arguments[2];
+
+  if (transformer === undefined) transformer = null;
+
+  if (readableStrategy === undefined) readableStrategy = {};
+
+  if (writableStrategy === undefined) writableStrategy = {};
+
+  let transformerDict = {};
+  if (transformer !== null) {
+    if ("start" in transformer) {
+      transformerDict["start"] = transformer["start"];
+      if (typeof transformerDict["start"] !== "function") $throwTypeError("transformer.start should be a function");
+    }
+    if ("transform" in transformer) {
+      transformerDict["transform"] = transformer["transform"];
+      if (typeof transformerDict["transform"] !== "function")
+        $throwTypeError("transformer.transform should be a function");
+    }
+    if ("flush" in transformer) {
+      transformerDict["flush"] = transformer["flush"];
+      if (typeof transformerDict["flush"] !== "function") $throwTypeError("transformer.flush should be a function");
+    }
+
+    if ("readableType" in transformer) throw new RangeError("TransformStream transformer has a readableType");
+    if ("writableType" in transformer) throw new RangeError("TransformStream transformer has a writableType");
+  }
+
+  const readableHighWaterMark = $extractHighWaterMark(readableStrategy, 0);
+  const readableSizeAlgorithm = $extractSizeAlgorithm(readableStrategy);
+
+  const writableHighWaterMark = $extractHighWaterMark(writableStrategy, 1);
+  const writableSizeAlgorithm = $extractSizeAlgorithm(writableStrategy);
+
+  const startPromiseCapability = $newPromiseCapability(Promise);
+  $initializeTransformStream(
+    this,
+    startPromiseCapability.$promise,
+    writableHighWaterMark,
+    writableSizeAlgorithm,
+    readableHighWaterMark,
+    readableSizeAlgorithm,
+  );
+  $setUpTransformStreamDefaultControllerFromTransformer(this, transformer, transformerDict);
+
+  if ("start" in transformerDict) {
+    const controller = $getByIdDirectPrivate(this, "controller");
+    const startAlgorithm = () => $promiseInvokeOrNoopMethodNoCatch(transformer, transformerDict["start"], [controller]);
+    startAlgorithm().$then(
+      () => {
+        // FIXME: We probably need to resolve start promise with the result of the start algorithm.
+        startPromiseCapability.$resolve.$call();
+      },
+      error => {
+        startPromiseCapability.$reject.$call(undefined, error);
+      },
+    );
+  } else startPromiseCapability.$resolve.$call();
+
+  return this;
+}
+
+$getter;
+export function readable() {
+  if (!$isTransformStream(this)) throw $makeThisTypeError("TransformStream", "readable");
+
+  return $getByIdDirectPrivate(this, "readable");
+}
+
+export function writable() {
+  if (!$isTransformStream(this)) throw $makeThisTypeError("TransformStream", "writable");
+
+  return $getByIdDirectPrivate(this, "writable");
+}