From aca63fd947408bfd22321774d7acbc13e55b2663 Mon Sep 17 00:00:00 2001
From: Shannon Booth <shannon@serenityos.org>
Date: Sun, 19 Nov 2023 12:11:47 +1300
Subject: [PATCH] LibWeb: Implement
 ReadableByteStreamControllerCommitPullIntoDescriptor

---
 .../LibWeb/Streams/AbstractOperations.cpp     | 39 +++++++++++++++++++
 .../LibWeb/Streams/AbstractOperations.h       |  1 +
 2 files changed, 40 insertions(+)

diff --git a/Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp b/Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp
index 73b6c0d597..6a72ed3803 100644
--- a/Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp
+++ b/Userland/Libraries/LibWeb/Streams/AbstractOperations.cpp
@@ -1719,6 +1719,45 @@ WebIDL::ExceptionOr<void> readable_byte_stream_controller_enqueue_detached_pull_
     return {};
 }
 
+// https://streams.spec.whatwg.org/#readable-byte-stream-controller-commit-pull-into-descriptor
+void readable_byte_stream_controller_commit_pull_into_descriptor(ReadableStream& stream, PullIntoDescriptor const& pull_into_descriptor)
+{
+    // 1. Assert: stream.[[state]] is not "errored".
+    VERIFY(!stream.is_errored());
+
+    // 2. Assert: pullIntoDescriptor.reader type is not "none".
+    VERIFY(pull_into_descriptor.reader_type != ReaderType::None);
+
+    // 3. Let done be false.
+    bool done = false;
+
+    // 4. If stream.[[state]] is "closed",
+    if (stream.is_closed()) {
+        // 1. Assert: pullIntoDescriptor’s bytes filled is 0.
+        VERIFY(pull_into_descriptor.bytes_filled == 0);
+
+        // 2. Set done to true.
+        done = true;
+    }
+
+    // 5. Let filledView be ! ReadableByteStreamControllerConvertPullIntoDescriptor(pullIntoDescriptor).
+    auto filled_view = readable_byte_stream_controller_convert_pull_into_descriptor(stream.realm(), pull_into_descriptor);
+
+    // 6. If pullIntoDescriptor’s reader type is "default",
+    if (pull_into_descriptor.reader_type == ReaderType::Default) {
+        // 1. Perform ! ReadableStreamFulfillReadRequest(stream, filledView, done).
+        readable_stream_fulfill_read_request(stream, filled_view, done);
+    }
+    // 7. Otherwise,
+    else {
+        // 1. Assert: pullIntoDescriptor’s reader type is "byob".
+        VERIFY(pull_into_descriptor.reader_type == ReaderType::Byob);
+
+        // 2. Perform ! ReadableStreamFulfillReadIntoRequest(stream, filledView, done).
+        readable_stream_fulfill_read_into_request(stream, filled_view, done);
+    }
+}
+
 // https://streams.spec.whatwg.org/#abstract-opdef-readablebytestreamcontrollerprocessreadrequestsusingqueue
 WebIDL::ExceptionOr<void> readable_byte_stream_controller_process_read_requests_using_queue(ReadableByteStreamController& controller)
 {
diff --git a/Userland/Libraries/LibWeb/Streams/AbstractOperations.h b/Userland/Libraries/LibWeb/Streams/AbstractOperations.h
index a7c17a5888..3d32b9ab8b 100644
--- a/Userland/Libraries/LibWeb/Streams/AbstractOperations.h
+++ b/Userland/Libraries/LibWeb/Streams/AbstractOperations.h
@@ -81,6 +81,7 @@ WebIDL::ExceptionOr<void> readable_stream_enqueue(ReadableStreamController& cont
 WebIDL::ExceptionOr<void> readable_byte_stream_controller_enqueue(ReadableByteStreamController& controller, JS::Value chunk);
 WebIDL::ExceptionOr<JS::NonnullGCPtr<JS::ArrayBuffer>> transfer_array_buffer(JS::Realm& realm, JS::ArrayBuffer& buffer);
 WebIDL::ExceptionOr<void> readable_byte_stream_controller_enqueue_detached_pull_into_queue(ReadableByteStreamController& controller, PullIntoDescriptor& pull_into_descriptor);
+void readable_byte_stream_controller_commit_pull_into_descriptor(ReadableStream&, PullIntoDescriptor const&);
 WebIDL::ExceptionOr<void> readable_byte_stream_controller_process_read_requests_using_queue(ReadableByteStreamController& controller);
 void readable_byte_stream_controller_enqueue_chunk_to_queue(ReadableByteStreamController& controller, JS::NonnullGCPtr<JS::ArrayBuffer> buffer, u32 byte_offset, u32 byte_length);
 WebIDL::ExceptionOr<void> readable_byte_stream_controller_enqueue_cloned_chunk_to_queue(ReadableByteStreamController& controller, JS::ArrayBuffer& buffer, u64 byte_offset, u64 byte_length);