LibJS: Implement the SortIndexedProperties AO

Also use it in array_merge_sort() instead of inlining the algorithm.

Userland/Libraries/LibJS/Runtime/Array.cpp

@@ -8,9 +8,11 @@
 #include <AK/Function.h>
 #include <LibJS/Runtime/AbstractOperations.h>
 #include <LibJS/Runtime/Array.h>
+#include <LibJS/Runtime/ArrayPrototype.h>
 #include <LibJS/Runtime/Completion.h>
 #include <LibJS/Runtime/Error.h>
 #include <LibJS/Runtime/GlobalObject.h>
+#include <LibJS/Runtime/NativeFunction.h>
 
 namespace JS {
 
@@ -199,6 +201,56 @@ ThrowCompletionOr<double> compare_array_elements(GlobalObject& global_object, Va
     return 0;
 }
 
+// 1.1.1.3 SortIndexedProperties ( obj, len, SortCompare, skipHoles ), https://tc39.es/proposal-change-array-by-copy/#sec-sortindexedproperties
+ThrowCompletionOr<MarkedVector<Value>> sort_indexed_properties(GlobalObject& global_object, Object const& object, size_t length, Function<ThrowCompletionOr<double>(Value, Value)> const& sort_compare, bool skip_holes)
+{
+    // 1. Let items be a new empty List.
+    auto items = MarkedVector<Value> { global_object.heap() };
+
+    // 2. Let k be 0.
+    // 3. Repeat, while k < len,
+    for (size_t k = 0; k < length; ++k) {
+        // a. Let Pk be ! ToString(𝔽(k)).
+        auto property_key = PropertyKey { k };
+
+        bool k_read;
+
+        // b. If skipHoles is true, then
+        if (skip_holes) {
+            // i. Let kRead be ? HasProperty(obj, Pk).
+            k_read = TRY(object.has_property(property_key));
+        }
+        // c. Else,
+        else {
+            // i. Let kRead be true.
+            k_read = true;
+        }
+
+        // d. If kRead is true, then
+        if (k_read) {
+            // i. Let kValue be ? Get(obj, Pk).
+            auto k_value = TRY(object.get(property_key));
+
+            // ii. Append kValue to items.
+            items.append(k_value);
+        }
+
+        // e. Set k to k + 1.
+    }
+
+    // 4. Sort items using an implementation-defined sequence of calls to SortCompare. If any such call returns an abrupt completion, stop before performing any further calls to SortCompare or steps in this algorithm and return that Completion Record.
+    // FIXME: Support AK::Function in array_merge_sort() to avoid having to create a NativeFunction.
+    auto* native_comparefn = NativeFunction::create(global_object, "", [&](auto& vm, auto&) -> ThrowCompletionOr<Value> {
+        auto x = vm.argument(0);
+        auto y = vm.argument(1);
+        return TRY(sort_compare(x, y));
+    });
+    TRY(array_merge_sort(global_object, native_comparefn, items));
+
+    // 5. Return items.
+    return items;
+}
+
 // NON-STANDARD: Used to return the value of the ephemeral length property
 ThrowCompletionOr<Optional<PropertyDescriptor>> Array::internal_get_own_property(PropertyKey const& property_key) const
 {

Userland/Libraries/LibJS/Runtime/Array.h

@@ -52,5 +52,6 @@ private:
 };
 
 ThrowCompletionOr<double> compare_array_elements(GlobalObject&, Value x, Value y, FunctionObject* comparefn);
+ThrowCompletionOr<MarkedVector<Value>> sort_indexed_properties(GlobalObject&, Object const&, size_t length, Function<ThrowCompletionOr<double>(Value, Value)> const& sort_compare, bool skip_holes);
 
 }

Userland/Libraries/LibJS/Runtime/ArrayPrototype.cpp

@@ -901,54 +901,13 @@ ThrowCompletionOr<void> array_merge_sort(GlobalObject& global_object, FunctionOb
         auto x = left[left_index];
         auto y = right[right_index];
 
-        double comparison_result;
-
-        if (x.is_undefined() && y.is_undefined()) {
-            comparison_result = 0;
-        } else if (x.is_undefined()) {
-            comparison_result = 1;
-        } else if (y.is_undefined()) {
-            comparison_result = -1;
-        } else if (compare_func) {
-            auto call_result = TRY(call(global_object, *compare_func, js_undefined(), left[left_index], right[right_index]));
-            auto number = TRY(call_result.to_number(global_object));
-            if (number.is_nan())
-                comparison_result = 0;
-            else
-                comparison_result = number.as_double();
-        } else {
-            // FIXME: It would probably be much better to be smarter about this and implement
-            // the Abstract Relational Comparison in line once iterating over code points, rather
-            // than calling it twice after creating two primitive strings.
-
-            auto x_string = TRY(x.to_primitive_string(global_object));
-
-            auto y_string = TRY(y.to_primitive_string(global_object));
-
-            auto x_string_value = Value(x_string);
-            auto y_string_value = Value(y_string);
-
-            // Because they are called with primitive strings, these is_less_than calls
-            // should never result in a VM exception.
-            auto x_lt_y_relation = MUST(is_less_than(global_object, true, x_string_value, y_string_value));
-            VERIFY(x_lt_y_relation != TriState::Unknown);
-            auto y_lt_x_relation = MUST(is_less_than(global_object, true, y_string_value, x_string_value));
-            VERIFY(y_lt_x_relation != TriState::Unknown);
-
-            if (x_lt_y_relation == TriState::True) {
-                comparison_result = -1;
-            } else if (y_lt_x_relation == TriState::True) {
-                comparison_result = 1;
-            } else {
-                comparison_result = 0;
-            }
-        }
+        double comparison_result = TRY(compare_array_elements(global_object, x, y, compare_func));
 
         if (comparison_result <= 0) {
-            arr_to_sort.append(left[left_index]);
+            arr_to_sort.append(x);
             left_index++;
         } else {
-            arr_to_sort.append(right[right_index]);
+            arr_to_sort.append(y);
             right_index++;
         }
     }