FEAT: Implement Symbol.unscopables

rhino/src/main/java/org/mozilla/javascript/NativeArray.java

@@ -45,11 +45,30 @@ public class NativeArray extends IdScriptableObject implements List {
 
     private static final Object ARRAY_TAG = "Array";
     private static final Long NEGATIVE_ONE = Long.valueOf(-1);
+    private static final String[] UNSCOPABLES = {
+        "at",
+        "copyWithin",
+        "entries",
+        "fill",
+        "find",
+        "findIndex",
+        "findLast",
+        "findLastIndex",
+        "flat",
+        "flatMap",
+        "includes",
+        "keys",
+        "toReversed",
+        "toSorted",
+        "toSpliced",
+        "values"
+    };
 
     static void init(Context cx, Scriptable scope, boolean sealed) {
         NativeArray obj = new NativeArray(0);
         IdFunctionObject constructor = obj.exportAsJSClass(MAX_PROTOTYPE_ID, scope, sealed);
         ScriptRuntimeES6.addSymbolSpecies(cx, scope, constructor);
+        ScriptRuntimeES6.addSymbolUnscopables(cx, scope, constructor);
     }
 
     static int getMaximumInitialCapacity() {
@@ -160,6 +179,11 @@ protected void fillConstructorProperties(IdFunctionObject ctor) {
 
     @Override
     protected void initPrototypeId(int id) {
+        if (id == SymbolId_unscopables) {
+            initPrototypeValue(id, SymbolKey.UNSCOPABLES, makeUnscopables(), DONTENUM | READONLY);
+            return;
+        }
+
         String s, fnName = null;
         int arity;
         switch (id) {
@@ -502,6 +526,25 @@ public void setPrototype(Scriptable p) {
         }
     }
 
+    private Object makeUnscopables() {
+        Context cx = Context.getCurrentContext();
+        NativeObject obj;
+
+        if (cx != null) {
+            Scriptable scope = this.getParentScope();
+            obj = (NativeObject) cx.newObject(scope);
+        } else {
+            obj = new NativeObject();
+        }
+
+        ScriptableObject desc = ScriptableObject.buildDataDescriptor(obj, true, EMPTY);
+        for (var k : UNSCOPABLES) {
+            obj.defineOwnProperty(cx, k, desc);
+        }
+        obj.setPrototype(null); // unscopables don't have any prototype
+        return obj;
+    }
+
     @Override
     public Object get(int index, Scriptable start) {
         if (!denseOnly && isGetterOrSetter(null, index, false)) return super.get(index, start);
@@ -2382,6 +2425,8 @@ protected int findPrototypeId(Symbol k) {
             // as the "values" property. We implement this by returning the
             // ID of "values" when the iterator symbol is accessed.
             return Id_values;
+        } else if (SymbolKey.UNSCOPABLES.equals(k)) {
+            return SymbolId_unscopables;
         }
         return 0;
     }
@@ -2533,7 +2578,8 @@ protected int findPrototypeId(String s) {
             Id_at = 32,
             Id_flat = 33,
             Id_flatMap = 34,
-            MAX_PROTOTYPE_ID = Id_flatMap;
+            SymbolId_unscopables = 35,
+            MAX_PROTOTYPE_ID = SymbolId_unscopables;
     private static final int ConstructorId_join = -Id_join,
             ConstructorId_reverse = -Id_reverse,
             ConstructorId_sort = -Id_sort,

rhino/src/main/java/org/mozilla/javascript/ScriptRuntimeES6.java

@@ -36,4 +36,14 @@ public static void addSymbolSpecies(
                                 thisObj));
         constructor.defineOwnProperty(cx, SymbolKey.SPECIES, speciesDescriptor, false);
     }
+
+    /** Registers the symbol <code>[Symbol.unscopables]</code> on the given constructor function. */
+    public static void addSymbolUnscopables(
+            Context cx, Scriptable scope, IdScriptableObject constructor) {
+        ScriptableObject unScopablesDescriptor = (ScriptableObject) cx.newObject(scope);
+        ScriptableObject.putProperty(unScopablesDescriptor, "enumerable", false);
+        ScriptableObject.putProperty(unScopablesDescriptor, "configurable", false);
+        ScriptableObject.putProperty(unScopablesDescriptor, "writable", false);
+        constructor.defineOwnProperty(cx, SymbolKey.UNSCOPABLES, unScopablesDescriptor, false);
+    }
 }

tests/testsrc/jstests/es6/array.js

@@ -22,4 +22,32 @@ assertEquals(a.map(_ => 'a'), ['a', 'a']);
 	assertEquals(Array, symbolSpeciesValue);
 })();
 
+(function TestSymbolUnScopables() {
+	var symbolUnscopablesValue = Array[Symbol.unscopables];
+	assertEquals(undefined, symbolUnscopablesValue);
+})();
+
+(function TestSymbolUnScopablesOnArray() {
+	var symbolValuesToAssert = '{' +
+								'"at":true,' +
+								'"copyWithin":true,' +
+								'"entries":true,' +
+								'"fill":true,' +
+								'"find":true,' +
+								'"findIndex":true,' +
+								'"findLast":true,' +
+								'"findLastIndex":true,' +
+								'"flat":true,' +
+								'"flatMap":true,' +
+								'"includes":true,' +
+								'"keys":true,' +
+								'"toReversed":true,' +
+								'"toSorted":true,' +
+								'"toSpliced":true,' +
+								'"values":true' +
+							'}';
+	var symbolValues = Array.prototype[Symbol.unscopables];
+	assertEquals(JSON.stringify(symbolValues), symbolValuesToAssert);
+})();
+
 "success";

tests/testsrc/test262.properties

@@ -26,7 +26,7 @@ harness 22/115 (19.13%)
     isConstructor.js {unsupported: [Reflect.construct]}
     nativeFunctionMatcher.js
 
-built-ins/Array 471/3055 (15.42%)
+built-ins/Array 468/3055 (15.32%)
     fromAsync 94/94 (100.0%)
     from/calling-from-valid-1-noStrict.js non-strict Spec pretty clearly says this should be undefined
     from/elements-deleted-after.js Checking to see if length changed, but spec says it should not
@@ -302,7 +302,7 @@ built-ins/Array 471/3055 (15.42%)
     prototype/splice/target-array-non-extensible.js
     prototype/splice/target-array-with-non-configurable-property.js
     prototype/Symbol.iterator/not-a-constructor.js {unsupported: [Reflect.construct]}
-    prototype/Symbol.unscopables 4/4 (100.0%)
+    prototype/Symbol.unscopables/change-array-by-copy.js
     prototype/toLocaleString/invoke-element-tolocalestring.js
     prototype/toLocaleString/not-a-constructor.js {unsupported: [Reflect.construct]}
     prototype/toLocaleString/primitive_this_value.js strict