From c0da3e356aeced8a8167f10f1d9023f26053d331 Mon Sep 17 00:00:00 2001
From: Timothy Flynn <trflynn89@pm.me>
Date: Fri, 15 Nov 2024 14:47:27 -0500
Subject: [PATCH] LibWeb: Add a couple ad-hoc BufferSource AOs

These helpers will be used by CompressionStream/DecompressionStream.
---
 .../LibWeb/WebIDL/AbstractOperations.cpp      | 21 +++++++++++++++++++
 Libraries/LibWeb/WebIDL/AbstractOperations.h  |  2 ++
 2 files changed, 23 insertions(+)

diff --git a/Libraries/LibWeb/WebIDL/AbstractOperations.cpp b/Libraries/LibWeb/WebIDL/AbstractOperations.cpp
index 405bc700f3..ca0cb380f9 100644
--- a/Libraries/LibWeb/WebIDL/AbstractOperations.cpp
+++ b/Libraries/LibWeb/WebIDL/AbstractOperations.cpp
@@ -23,6 +23,27 @@
 
 namespace Web::WebIDL {
 
+bool is_buffer_source_type(JS::Value value)
+{
+    if (!value.is_object())
+        return false;
+
+    auto const& object = value.as_object();
+    return is<JS::TypedArrayBase>(object) || is<JS::DataView>(object) || is<JS::ArrayBuffer>(object);
+}
+
+GC::Ptr<JS::ArrayBuffer> underlying_buffer_source(JS::Object& buffer_source)
+{
+    if (is<JS::TypedArrayBase>(buffer_source))
+        return static_cast<JS::TypedArrayBase&>(buffer_source).viewed_array_buffer();
+    if (is<JS::DataView>(buffer_source))
+        return static_cast<JS::DataView&>(buffer_source).viewed_array_buffer();
+    if (is<JS::ArrayBuffer>(buffer_source))
+        return static_cast<JS::ArrayBuffer&>(buffer_source);
+
+    VERIFY_NOT_REACHED();
+}
+
 // https://webidl.spec.whatwg.org/#dfn-get-buffer-source-copy
 ErrorOr<ByteBuffer> get_buffer_source_copy(JS::Object const& buffer_source)
 {
diff --git a/Libraries/LibWeb/WebIDL/AbstractOperations.h b/Libraries/LibWeb/WebIDL/AbstractOperations.h
index 46fb1acb5f..6051a8d0ef 100644
--- a/Libraries/LibWeb/WebIDL/AbstractOperations.h
+++ b/Libraries/LibWeb/WebIDL/AbstractOperations.h
@@ -17,6 +17,8 @@
 
 namespace Web::WebIDL {
 
+bool is_buffer_source_type(JS::Value);
+GC::Ptr<JS::ArrayBuffer> underlying_buffer_source(JS::Object& buffer_source);
 ErrorOr<ByteBuffer> get_buffer_source_copy(JS::Object const& buffer_source);
 
 JS::Completion call_user_object_operation(WebIDL::CallbackType& callback, String const& operation_name, Optional<JS::Value> this_argument, GC::MarkedVector<JS::Value> args);