JSS.Lib: Implement the HasThisBinding abstract operation

JSS.Lib/Execution/DeclarativeEnvironment.cs

@@ -137,5 +137,12 @@ override public Completion GetBindingValue(string N, bool S)
         return Completion.NormalCompletion(binding.Value);
     }
 
+    // 9.1.1.1.8 HasThisBinding ( ), https://tc39.es/ecma262/#sec-declarative-environment-records-hasthisbinding
+    override public bool HasThisBinding()
+    {
+        // 1. Return false.
+        return false;
+    }
+
     private readonly Dictionary<string, Binding> _identifierToBinding = new();
 }

JSS.Lib/Execution/Environment.cs

@@ -1,6 +1,5 @@
 using JSS.Lib.AST.Values;
 using ValueType = JSS.Lib.AST.Values.ValueType;
-using Object = JSS.Lib.AST.Values.Object;
 
 namespace JSS.Lib.Execution;
 
@@ -18,7 +17,7 @@ internal abstract class Environment : Value
     virtual public Completion SetMutableBinding(string N, Value V, bool S) { throw new NotImplementedException(); }
     virtual public Completion GetBindingValue(string N, bool S) { throw new NotImplementedException(); }
     virtual public Completion DeleteBinding(string N) { throw new NotImplementedException(); }
-    virtual public bool HasThisBinding() { throw new NotImplementedException(); }
+    abstract public bool HasThisBinding();
     virtual public bool HasSuperBinding() { throw new NotImplementedException(); }
     virtual public Value WithBaseObject() { throw new NotImplementedException(); }
     virtual public Completion GetThisBinding() { throw new InvalidOperationException(); }

JSS.Lib/Execution/FunctionEnvironment.cs

@@ -64,8 +64,15 @@ public Completion BindThisValue(Value V)
         return Completion.NormalCompletion(V);
     }
 
+    // 9.1.1.3.2 HasThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-hasthisbinding
+    override public bool HasThisBinding()
+    {
+        // 1. If envRec.[[ThisBindingStatus]] is LEXICAL, return false; otherwise, return true.
+        return ThisBindingStatus != ThisBindingStatus.LEXICAL;
+    }
+
     // 9.1.1.3.4 GetThisBinding ( ), https://tc39.es/ecma262/#sec-function-environment-records-getthisbinding
-    public override Completion GetThisBinding()
+    override public Completion GetThisBinding()
     {
         // 1. Assert: envRec.[[ThisBindingStatus]] is not LEXICAL.
         Debug.Assert(ThisBindingStatus != ThisBindingStatus.LEXICAL);

JSS.Lib/Execution/GlobalEnvironment.cs

@@ -125,6 +125,13 @@ override public Completion GetBindingValue(string N, bool S)
         return ObjectRecord.GetBindingValue(N, S);
     }
 
+    // 9.1.1.4.8 HasThisBinding ( ), https://tc39.es/ecma262/#sec-global-environment-records-hasthisbinding
+    public override bool HasThisBinding()
+    {
+        // 1. Return true.
+        return true;
+    }
+
     // 9.1.1.4.11 GetThisBinding ( ), https://tc39.es/ecma262/#sec-global-environment-records-getthisbinding
     public override Completion GetThisBinding()
     {

JSS.Lib/Execution/ObjectEnvironment.cs

@@ -119,6 +119,13 @@ override public Completion GetBindingValue(string N, bool S)
         return Object.Get(BindingObject, N);
     }
 
+    // 9.1.1.2.8 HasThisBinding ( ), https://tc39.es/ecma262/#sec-object-environment-records-hasthisbinding
+    override public bool HasThisBinding()
+    {
+        // 1. Return false.
+        return false;
+    }
+
     public Object BindingObject { get; }
     public bool IsWithEnvironment { get; }
 }