LibWeb: Implement ReadableStreamBYOBReader constructor

Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBReader.cpp

@@ -1,12 +1,15 @@
 /*
  * Copyright (c) 2023, Matthew Olsson <mattco@serenityos.org>
+ * Copyright (c) 2023, Shannon Booth <shannon@serenityos.org>
  *
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
 #include <LibJS/Runtime/PromiseCapability.h>
+#include <LibWeb/Streams/AbstractOperations.h>
 #include <LibWeb/Streams/ReadableStream.h>
 #include <LibWeb/Streams/ReadableStreamBYOBReader.h>
+#include <LibWeb/WebIDL/ExceptionOr.h>
 
 namespace Web::Streams {
 
@@ -16,6 +19,17 @@ ReadableStreamBYOBReader::ReadableStreamBYOBReader(JS::Realm& realm)
 {
 }
 
+// https://streams.spec.whatwg.org/#byob-reader-constructor
+WebIDL::ExceptionOr<JS::NonnullGCPtr<ReadableStreamBYOBReader>> ReadableStreamBYOBReader::construct_impl(JS::Realm& realm, JS::NonnullGCPtr<ReadableStream> stream)
+{
+    auto reader = realm.heap().allocate<ReadableStreamBYOBReader>(realm, realm);
+
+    // 1. Perform ? SetUpReadableStreamBYOBReader(this, stream).
+    TRY(set_up_readable_stream_byob_reader(reader, *stream));
+
+    return reader;
+}
+
 void ReadableStreamBYOBReader::visit_edges(Cell::Visitor& visitor)
 {
     Base::visit_edges(visitor);

Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBReader.h

@@ -37,6 +37,8 @@ class ReadableStreamBYOBReader final
     WEB_PLATFORM_OBJECT(ReadableStreamBYOBReader, Bindings::PlatformObject);
 
 public:
+    static WebIDL::ExceptionOr<JS::NonnullGCPtr<ReadableStreamBYOBReader>> construct_impl(JS::Realm&, JS::NonnullGCPtr<ReadableStream>);
+
     virtual ~ReadableStreamBYOBReader() override = default;
 
     Vector<NonnullRefPtr<ReadIntoRequest>>& read_into_requests() { return m_read_into_requests; }

Userland/Libraries/LibWeb/Streams/ReadableStreamBYOBReader.idl

@@ -1,10 +1,12 @@
+#import <Streams/ReadableStream.idl>
 #import <Streams/ReadableStreamGenericReader.idl>
 
+// https://streams.spec.whatwg.org/#readablestreambyobreader
 [Exposed=*]
 interface ReadableStreamBYOBReader {
-    // FIXME: Implement
-    // constructor(ReadableStream stream);
+    constructor(ReadableStream stream);
 
+    // FIXME: Implement
     // Promise<ReadableStreamReadResult> read(ArrayBufferView view);
     // undefined releaseLock();
 };