From 8333055c3d9e0a05c058cbc4d00845711deb9593 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Fri, 1 Jan 2021 17:00:20 +0100
Subject: [PATCH] LibJS: Use RTTI for inheritance checks

This replaces the hand-rolled string-based inheritance check tech.
---
 Applications/Spreadsheet/JSIntegration.cpp           |  2 +-
 Libraries/LibJS/Runtime/Object.h                     | 11 ++++-------
 Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp |  4 ++--
 3 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/Applications/Spreadsheet/JSIntegration.cpp b/Applications/Spreadsheet/JSIntegration.cpp
index a10d8a884d..12a249593e 100644
--- a/Applications/Spreadsheet/JSIntegration.cpp
+++ b/Applications/Spreadsheet/JSIntegration.cpp
@@ -419,7 +419,7 @@ JS_DEFINE_NATIVE_FUNCTION(WorkbookObject::sheet)
     if (!this_object)
         return {};
 
-    if (!this_object->inherits("WorkbookObject")) {
+    if (!is<WorkbookObject>(this_object)) {
         vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotA, "WorkbookObject");
         return {};
     }
diff --git a/Libraries/LibJS/Runtime/Object.h b/Libraries/LibJS/Runtime/Object.h
index 94b93c1211..50d756ab27 100644
--- a/Libraries/LibJS/Runtime/Object.h
+++ b/Libraries/LibJS/Runtime/Object.h
@@ -39,11 +39,10 @@
 
 namespace JS {
 
-#define JS_OBJECT(class_, base_class)                                   \
-public:                                                                 \
-    using Base = base_class;                                            \
-    virtual const char* class_name() const override { return #class_; } \
-    virtual bool inherits(const StringView& class_name) const override { return class_name == #class_ || Base::inherits(class_name); }
+#define JS_OBJECT(class_, base_class) \
+public:                               \
+    using Base = base_class;          \
+    virtual const char* class_name() const override { return #class_; }
 
 struct PropertyDescriptor {
     PropertyAttributes attributes;
@@ -67,8 +66,6 @@ public:
     virtual void initialize(GlobalObject&) override;
     virtual ~Object();
 
-    virtual bool inherits(const StringView& class_name) const { return class_name == this->class_name(); }
-
     enum class PropertyKind {
         Key,
         Value,
diff --git a/Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp b/Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp
index 5e314a8674..90cf49ef19 100644
--- a/Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp
+++ b/Libraries/LibWeb/CodeGenerators/WrapperGenerator.cpp
@@ -639,7 +639,7 @@ static @fully_qualified_name@* impl_from(JS::VM& vm, JS::GlobalObject& global_ob
     auto* this_object = vm.this_value(global_object).to_object(global_object);
     if (!this_object)
         return {};
-    if (!this_object->inherits("@wrapper_class@")) {
+    if (!is<@wrapper_class@>(this_object)) {
         vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotA, "@fully_qualified_name@");
         return nullptr;
     }
@@ -694,7 +694,7 @@ static @fully_qualified_name@* impl_from(JS::VM& vm, JS::GlobalObject& global_ob
     if (vm.exception())
         @return_statement@
 
-    if (!@cpp_name@_object->inherits("@parameter.type.name@Wrapper")) {
+    if (!is<@parameter.type.name@Wrapper>(@cpp_name@_object)) {
         vm.throw_exception<JS::TypeError>(global_object, JS::ErrorType::NotA, "@parameter.type.name@");
         @return_statement@
     }