LibJS: Remove Object::is_array() in favor of Value::is_array() and RTTI

It's way too easy to get this wrong: for the IsArray abstract operation,
Value::is_array() needs to be called. Since we have RTTI, the virtual
Object::is_array() method is not needed anymore - if we need to know
whether something is *actually* a JS::Array (we currently check in more
cases than we should, I think) and not a Proxy with an Array target, we
should do that in a way that doesn't look like an abstract operation.

8 files changed, 8 insertions, 11 deletions

diff --git a/Userland/Libraries/LibJS/AST.cpp b/Userland/Libraries/LibJS/AST.cpp
index 5fdbc1d60c..2100d92566 100644
--- a/Userland/Libraries/LibJS/AST.cpp
+++ b/Userland/Libraries/LibJS/AST.cpp
@@ -1810,7 +1810,7 @@ Value ObjectExpression::execute(Interpreter& interpreter, GlobalObject& global_o
             return {};
 
         if (property.type() == ObjectProperty::Type::Spread) {
-            if (key.is_object() && key.as_object().is_array()) {
+            if (key.is_object() && is<Array>(key.as_object())) {
                 auto& array_to_spread = static_cast<Array&>(key.as_object());
                 for (auto& entry : array_to_spread.indexed_properties()) {
                     auto value = array_to_spread.get(entry.index());
diff --git a/Userland/Libraries/LibJS/MarkupGenerator.cpp b/Userland/Libraries/LibJS/MarkupGenerator.cpp
index cce056286f..bbe739b55e 100644
--- a/Userland/Libraries/LibJS/MarkupGenerator.cpp
+++ b/Userland/Libraries/LibJS/MarkupGenerator.cpp
@@ -61,7 +61,7 @@ void MarkupGenerator::value_to_html(Value value, StringBuilder& output_html, Has
 
     if (value.is_object()) {
         auto& object = value.as_object();
-        if (object.is_array())
+        if (is<Array>(object))
             return array_to_html(static_cast<const Array&>(object), output_html, seen_objects);
         output_html.append(wrap_string_in_style(object.class_name(), StyleType::ObjectType));
         if (object.is_function())
diff --git a/Userland/Libraries/LibJS/Runtime/Array.cpp b/Userland/Libraries/LibJS/Runtime/Array.cpp
index e7d60de6c2..9525238271 100644
--- a/Userland/Libraries/LibJS/Runtime/Array.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Array.cpp
@@ -68,7 +68,7 @@ Array* Array::typed_this(VM& vm, GlobalObject& global_object)
     auto* this_object = vm.this_value(global_object).to_object(global_object);
     if (!this_object)
         return {};
-    if (!this_object->is_array()) {
+    if (!is<Array>(this_object)) {
         vm.throw_exception<TypeError>(global_object, ErrorType::NotAn, "Array");
         return nullptr;
     }
diff --git a/Userland/Libraries/LibJS/Runtime/Array.h b/Userland/Libraries/LibJS/Runtime/Array.h
index 077a2ad29b..41f3a7a809 100644
--- a/Userland/Libraries/LibJS/Runtime/Array.h
+++ b/Userland/Libraries/LibJS/Runtime/Array.h
@@ -24,8 +24,6 @@ public:
     static Array* typed_this(VM&, GlobalObject&);
 
 private:
-    virtual bool is_array() const override { return true; }
-
     JS_DECLARE_NATIVE_GETTER(length_getter);
     JS_DECLARE_NATIVE_SETTER(length_setter);
 };
diff --git a/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp b/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
index c192404548..5067d69c17 100644
--- a/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp
@@ -348,7 +348,7 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::push)
     auto* this_object = vm.this_value(global_object).to_object(global_object);
     if (!this_object)
         return {};
-    if (this_object->is_array()) {
+    if (is<Array>(this_object)) {
         auto* array = static_cast<Array*>(this_object);
         for (size_t i = 0; i < vm.argument_count(); ++i)
             array->indexed_properties().append(vm.argument(i));
@@ -432,7 +432,7 @@ JS_DEFINE_NATIVE_FUNCTION(ArrayPrototype::pop)
     auto* this_object = vm.this_value(global_object).to_object(global_object);
     if (!this_object)
         return {};
-    if (this_object->is_array()) {
+    if (is<Array>(this_object)) {
         auto* array = static_cast<Array*>(this_object);
         if (array->indexed_properties().is_empty())
             return js_undefined();
diff --git a/Userland/Libraries/LibJS/Runtime/Object.h b/Userland/Libraries/LibJS/Runtime/Object.h
index 178fe4c3c6..be08581bf3 100644
--- a/Userland/Libraries/LibJS/Runtime/Object.h
+++ b/Userland/Libraries/LibJS/Runtime/Object.h
@@ -132,7 +132,6 @@ public:
     void define_native_property(PropertyName const&, Function<Value(VM&, GlobalObject&)> getter, Function<void(VM&, GlobalObject&, Value)> setter, PropertyAttributes attributes);
     void define_native_accessor(PropertyName const&, Function<Value(VM&, GlobalObject&)> getter, Function<Value(VM&, GlobalObject&)> setter, PropertyAttributes attributes);
 
-    virtual bool is_array() const { return false; }
     virtual bool is_function() const { return false; }
     virtual bool is_typed_array() const { return false; }
     virtual bool is_string_object() const { return false; }
diff --git a/Userland/Libraries/LibJS/Runtime/Value.cpp b/Userland/Libraries/LibJS/Runtime/Value.cpp
index e626eb401a..a8398034e2 100644
--- a/Userland/Libraries/LibJS/Runtime/Value.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Value.cpp
@@ -203,7 +203,7 @@ bool Value::is_array(GlobalObject& global_object) const
     if (!is_object())
         return false;
     auto& object = as_object();
-    if (object.is_array())
+    if (is<Array>(object))
         return true;
     if (is<ProxyObject>(object)) {
         auto& proxy = static_cast<ProxyObject const&>(object);
@@ -219,7 +219,7 @@ bool Value::is_array(GlobalObject& global_object) const
 
 Array& Value::as_array()
 {
-    VERIFY(is_object() && as_object().is_array());
+    VERIFY(is_object() && is<Array>(as_object()));
     return static_cast<Array&>(*m_value.as_object);
 }
 
diff --git a/Userland/Utilities/js.cpp b/Userland/Utilities/js.cpp
index 8716fef063..90749d5bbb 100644
--- a/Userland/Utilities/js.cpp
+++ b/Userland/Utilities/js.cpp
@@ -452,7 +452,7 @@ static void print_value(JS::Value value, HashTable<JS::Object*>& seen_objects)
 
     if (value.is_object()) {
         auto& object = value.as_object();
-        if (object.is_array())
+        if (is<JS::Array>(object))
             return print_array(static_cast<JS::Array&>(object), seen_objects);
         if (object.is_function())
             return print_function(object, seen_objects);