LibJS: Add spec comments to Object

Userland/Libraries/LibJS/Runtime/Object.cpp

@@ -429,23 +429,43 @@ ThrowCompletionOr<MarkedVector<Value>> Object::enumerable_own_property_names(Pro
 // 7.3.26 CopyDataProperties ( target, source, excludedItems ), https://tc39.es/ecma262/#sec-copydataproperties
 ThrowCompletionOr<void> Object::copy_data_properties(VM& vm, Value source, HashTable<PropertyKey> const& seen_names)
 {
+    // 1. If source is either undefined or null, return unused.
     if (source.is_nullish())
         return {};
 
-    auto from_object = MUST(source.to_object(vm));
+    // 2. Let from be ! ToObject(source).
+    auto from = MUST(source.to_object(vm));
 
-    for (auto& next_key_value : TRY(from_object->internal_own_property_keys())) {
+    // 3. Let keys be ? from.[[OwnPropertyKeys]]().
+    auto keys = TRY(from->internal_own_property_keys());
+
+    // 4. For each element nextKey of keys, do
+    for (auto& next_key_value : keys) {
         auto next_key = MUST(PropertyKey::from_value(vm, next_key_value));
+
+        // a. Let excluded be false.
+        // b. For each element e of excludedItems, do
+        //    i. If SameValue(e, nextKey) is true, then
+        //        1. Set excluded to true.
         if (seen_names.contains(next_key))
             continue;
 
-        auto desc = TRY(from_object->internal_get_own_property(next_key));
+        // c. If excluded is false, then
 
+        // i. Let desc be ? from.[[GetOwnProperty]](nextKey).
+        auto desc = TRY(from->internal_get_own_property(next_key));
+
+        // ii. If desc is not undefined and desc.[[Enumerable]] is true, then
         if (desc.has_value() && desc->attributes().is_enumerable()) {
-            auto prop_value = TRY(from_object->get(next_key));
-            TRY(create_data_property_or_throw(next_key, prop_value));
+            // 1. Let propValue be ? Get(from, nextKey).
+            auto prop_value = TRY(from->get(next_key));
+
+            // 2. Perform ! CreateDataPropertyOrThrow(target, nextKey, propValue).
+            MUST(create_data_property_or_throw(next_key, prop_value));
         }
     }
+
+    // 5. Return unused.
     return {};
 }
 
@@ -455,14 +475,18 @@ PrivateElement* Object::private_element_find(PrivateName const& name)
     if (!m_private_elements)
         return nullptr;
 
-    auto element = m_private_elements->find_if([&](auto const& element) {
+    // 1. If O.[[PrivateElements]] contains a PrivateElement pe such that pe.[[Key]] is P, then
+    auto it = m_private_elements->find_if([&](auto const& element) {
         return element.key == name;
     });
 
-    if (element.is_end())
-        return nullptr;
+    if (!it.is_end()) {
+        // a. Return pe.
+        return &(*it);
+    }
 
-    return &(*element);
+    // 2. Return empty.
+    return nullptr;
 }
 
 // 7.3.28 PrivateFieldAdd ( O, P, value ), https://tc39.es/ecma262/#sec-privatefieldadd
@@ -518,58 +542,87 @@ ThrowCompletionOr<void> Object::private_method_or_accessor_add(PrivateElement el
     return {};
 }
 
-// 7.3.30 PrivateGet ( O, P ), https://tc39.es/ecma262/#sec-privateget
+// 7.3.31 PrivateGet ( O, P ), https://tc39.es/ecma262/#sec-privateget
 ThrowCompletionOr<Value> Object::private_get(PrivateName const& name)
 {
     auto& vm = this->vm();
 
+    // 1. Let entry be PrivateElementFind(O, P).
     auto* entry = private_element_find(name);
+
+    // 2. If entry is empty, throw a TypeError exception.
     if (!entry)
         return vm.throw_completion<TypeError>(ErrorType::PrivateFieldDoesNotExistOnObject, name.description);
 
     auto& value = entry->value;
 
-    if (entry->kind != PrivateElement::Kind::Accessor)
+    // 3. If entry.[[Kind]] is either field or method, then
+    if (entry->kind != PrivateElement::Kind::Accessor) {
+        // a. Return entry.[[Value]].
         return value;
+    }
 
+    // Assert: entry.[[Kind]] is accessor.
     VERIFY(value.is_accessor());
+
+    // 6. Let getter be entry.[[Get]].
     auto* getter = value.as_accessor().getter();
+
+    // 5. If entry.[[Get]] is undefined, throw a TypeError exception.
     if (!getter)
         return vm.throw_completion<TypeError>(ErrorType::PrivateFieldGetAccessorWithoutGetter, name.description);
 
-    // 8. Return ? Call(getter, Receiver).
+    // 7. Return ? Call(getter, O).
     return TRY(call(vm, *getter, this));
 }
 
-// 7.3.31 PrivateSet ( O, P, value ), https://tc39.es/ecma262/#sec-privateset
+// 7.3.32 PrivateSet ( O, P, value ), https://tc39.es/ecma262/#sec-privateset
 ThrowCompletionOr<void> Object::private_set(PrivateName const& name, Value value)
 {
     auto& vm = this->vm();
 
+    // 1. Let entry be PrivateElementFind(O, P).
     auto* entry = private_element_find(name);
+
+    // 2. If entry is empty, throw a TypeError exception.
     if (!entry)
         return vm.throw_completion<TypeError>(ErrorType::PrivateFieldDoesNotExistOnObject, name.description);
 
+    // 3. If entry.[[Kind]] is field, then
     if (entry->kind == PrivateElement::Kind::Field) {
+        // a. Set entry.[[Value]] to value.
         entry->value = value;
         return {};
-    } else if (entry->kind == PrivateElement::Kind::Method) {
+    }
+    // 4. Else if entry.[[Kind]] is method, then
+    else if (entry->kind == PrivateElement::Kind::Method) {
+        // a. Throw a TypeError exception.
         return vm.throw_completion<TypeError>(ErrorType::PrivateFieldSetMethod, name.description);
     }
 
+    // 5. Else,
+
+    // a. Assert: entry.[[Kind]] is accessor.
     VERIFY(entry->kind == PrivateElement::Kind::Accessor);
 
     auto& accessor = entry->value;
     VERIFY(accessor.is_accessor());
+
+    // c. Let setter be entry.[[Set]].
     auto* setter = accessor.as_accessor().setter();
+
+    // b. If entry.[[Set]] is undefined, throw a TypeError exception.
     if (!setter)
         return vm.throw_completion<TypeError>(ErrorType::PrivateFieldSetAccessorWithoutSetter, name.description);
 
+    // d. Perform ? Call(setter, O, « value »).
     TRY(call(vm, *setter, this, value));
+
+    // 6. Return unused.
     return {};
 }
 
-// 7.3.32 DefineField ( receiver, fieldRecord ), https://tc39.es/ecma262/#sec-definefield
+// 7.3.33 DefineField ( receiver, fieldRecord ), https://tc39.es/ecma262/#sec-definefield
 ThrowCompletionOr<void> Object::define_field(ClassFieldDefinition const& field)
 {
     auto& vm = this->vm();
@@ -605,7 +658,7 @@ ThrowCompletionOr<void> Object::define_field(ClassFieldDefinition const& field)
     return {};
 }
 
-// 7.3.33 InitializeInstanceElements ( O, constructor ), https://tc39.es/ecma262/#sec-initializeinstanceelements
+// 7.3.34 InitializeInstanceElements ( O, constructor ), https://tc39.es/ecma262/#sec-initializeinstanceelements
 ThrowCompletionOr<void> Object::initialize_instance_elements(ECMAScriptFunctionObject& constructor)
 {
     // 1. Let methods be the value of constructor.[[PrivateMethods]].