LibWeb: Add a 'get a reader' helper method on ReadableStream

Author: https://github.com/shannonbooth
Commit: 9ce0c5914b
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/3029
Reviewed-by: https://github.com/kennethmyhra ✅

Libraries/LibWeb/Fetch/Infrastructure/HTTP/Bodies.cpp

@@ -90,7 +90,7 @@ void Body::fully_read(JS::Realm& realm, Web::Fetch::Infrastructure::Body::Proces
 
     // 4. Let reader be the result of getting a reader for body’s stream. If that threw an exception, then run errorSteps
     //    with that exception and return.
-    auto reader = Streams::acquire_readable_stream_default_reader(m_stream);
+    auto reader = m_stream->get_a_reader();
 
     if (reader.is_exception()) {
         auto throw_completion = Bindings::exception_to_throw_completion(realm.vm(), reader.release_error());
@@ -113,7 +113,7 @@ void Body::incrementally_read(ProcessBodyChunkCallback process_body_chunk, Proce
 
     // 2. Let reader be the result of getting a reader for body’s stream.
     // NOTE: This operation will not throw an exception.
-    auto reader = MUST(Streams::acquire_readable_stream_default_reader(m_stream));
+    auto reader = MUST(m_stream->get_a_reader());
 
     // 3. Perform the incrementally-read loop given reader, taskDestination, processBodyChunk, processEndOfBody, and processBodyError.
     incrementally_read_loop(reader, task_destination.get<GC::Ref<JS::Object>>(), process_body_chunk, process_end_of_body, process_body_error);

Libraries/LibWeb/FileAPI/Blob.cpp

@@ -376,7 +376,7 @@ GC::Ref<WebIDL::Promise> Blob::text()
     auto stream = get_stream();
 
     // 2. Let reader be the result of getting a reader from stream. If that threw an exception, return a new promise rejected with that exception.
-    auto reader_or_exception = acquire_readable_stream_default_reader(*stream);
+    auto reader_or_exception = stream->get_a_reader();
     if (reader_or_exception.is_exception())
         return WebIDL::create_rejected_promise_from_exception(realm, reader_or_exception.release_error());
     auto reader = reader_or_exception.release_value();
@@ -405,7 +405,7 @@ GC::Ref<WebIDL::Promise> Blob::array_buffer()
     auto stream = get_stream();
 
     // 2. Let reader be the result of getting a reader from stream. If that threw an exception, return a new promise rejected with that exception.
-    auto reader_or_exception = acquire_readable_stream_default_reader(*stream);
+    auto reader_or_exception = stream->get_a_reader();
     if (reader_or_exception.is_exception())
         return WebIDL::create_rejected_promise_from_exception(realm, reader_or_exception.release_error());
     auto reader = reader_or_exception.release_value();
@@ -432,7 +432,7 @@ GC::Ref<WebIDL::Promise> Blob::bytes()
     auto stream = get_stream();
 
     // 2. Let reader be the result of getting a reader from stream. If that threw an exception, return a new promise rejected with that exception.
-    auto reader_or_exception = acquire_readable_stream_default_reader(*stream);
+    auto reader_or_exception = stream->get_a_reader();
     if (reader_or_exception.is_exception())
         return WebIDL::create_rejected_promise_from_exception(realm, reader_or_exception.release_error());
     auto reader = reader_or_exception.release_value();

Libraries/LibWeb/FileAPI/FileReader.cpp

@@ -134,7 +134,7 @@ WebIDL::ExceptionOr<void> FileReader::read_operation(Blob& blob, Type type, Opti
     auto stream = blob.get_stream();
 
     // 6. Let reader be the result of getting a reader from stream.
-    auto reader = TRY(acquire_readable_stream_default_reader(*stream));
+    auto reader = TRY(stream->get_a_reader());
 
     // 7. Let bytes be an empty byte sequence.
     ByteBuffer bytes;

Libraries/LibWeb/Streams/ReadableStream.cpp

@@ -259,6 +259,13 @@ bool ReadableStream::is_disturbed() const
     return m_disturbed;
 }
 
+// https://streams.spec.whatwg.org/#readablestream-get-a-reader
+WebIDL::ExceptionOr<GC::Ref<ReadableStreamDefaultReader>> ReadableStream::get_a_reader()
+{
+    // To get a reader for a ReadableStream stream, return ? AcquireReadableStreamDefaultReader(stream). The result will be a ReadableStreamDefaultReader.
+    return TRY(acquire_readable_stream_default_reader(*this));
+}
+
 // https://streams.spec.whatwg.org/#readablestream-pull-from-bytes
 WebIDL::ExceptionOr<void> ReadableStream::pull_from_bytes(ByteBuffer bytes)
 {

Libraries/LibWeb/Streams/ReadableStream.h

@@ -105,6 +105,7 @@ public:
     State state() const { return m_state; }
     void set_state(State value) { m_state = value; }
 
+    WebIDL::ExceptionOr<GC::Ref<ReadableStreamDefaultReader>> get_a_reader();
     WebIDL::ExceptionOr<void> pull_from_bytes(ByteBuffer);
     WebIDL::ExceptionOr<void> enqueue(JS::Value chunk);
     void set_up_with_byte_reading_support(GC::Ptr<PullAlgorithm> = {}, GC::Ptr<CancelAlgorithm> = {}, double high_water_mark = 0);