Support custom CLR object creator for ObjectInstance.ToObject (#1140)

Jint.Tests/Runtime/InteropTests.cs

@@ -919,8 +919,8 @@ namespace Jint.Tests.Runtime
             var name = e.Evaluate("o.values.filter(x => x.age == 12)[0].name").ToString();
             Assert.Equal("John", name);
         }
-        
-                
+
+
         [Fact]
         public void CanSetIsConcatSpreadableForArrays()
         {
@@ -946,7 +946,7 @@ namespace Jint.Tests.Runtime
 
             Assert.True(engine.Evaluate("list1[Symbol.isConcatSpreadable] = true; list1[Symbol.isConcatSpreadable];").AsBoolean());
             Assert.True(engine.Evaluate("list2[Symbol.isConcatSpreadable] = true; list2[Symbol.isConcatSpreadable];").AsBoolean());
-            
+
             Assert.Equal("[\"A\",\"B\",\"C\"]", engine.Evaluate("JSON.stringify(array1);"));
             Assert.Equal("[\"D\",\"E\",\"F\"]", engine.Evaluate("JSON.stringify(array2);"));
             Assert.Equal("[\"A\",\"B\",\"C\"]", engine.Evaluate("JSON.stringify(list1);"));
@@ -957,10 +957,10 @@ namespace Jint.Tests.Runtime
             Assert.Equal(Concatenated, engine.Evaluate("JSON.stringify(array1.concat(list2));"));
             Assert.Equal(Concatenated, engine.Evaluate("JSON.stringify(list1.concat(array2));"));
             Assert.Equal(Concatenated, engine.Evaluate("JSON.stringify(list1.concat(list2));"));
-            
+
             Assert.False(engine.Evaluate("list1[Symbol.isConcatSpreadable] = false; list1[Symbol.isConcatSpreadable];").AsBoolean());
             Assert.False(engine.Evaluate("list2[Symbol.isConcatSpreadable] = false; list2[Symbol.isConcatSpreadable];").AsBoolean());
-            
+
             Assert.Equal("[[\"A\",\"B\",\"C\"]]", engine.Evaluate("JSON.stringify([].concat(list1));"));
             Assert.Equal("[[\"A\",\"B\",\"C\"],[\"D\",\"E\",\"F\"]]", engine.Evaluate("JSON.stringify(list1.concat(list2));"));
         }
@@ -2850,13 +2850,13 @@ namespace Jint.Tests.Runtime
 
             Assert.Equal("x['First']: 1", _engine.Evaluate("\"x['First']: \" + x['First']"));
             Assert.Equal("[\"First\",\"Second\"]", _engine.Evaluate("JSON.stringify(Object.keys(x))"));
-            
+
             Assert.Equal("x['Third']: undefined", _engine.Evaluate("\"x['Third']: \" + x['Third']"));
             Assert.Equal("[\"First\",\"Second\"]", _engine.Evaluate("JSON.stringify(Object.keys(x))"));
-            
+
             Assert.Equal(JsValue.Undefined, _engine.Evaluate("x.length"));
             Assert.Equal("[\"First\",\"Second\"]", _engine.Evaluate("JSON.stringify(Object.keys(x))"));
-            
+
             Assert.Equal(2, _engine.Evaluate("x.Count").AsNumber());
             Assert.Equal("[\"First\",\"Second\"]", _engine.Evaluate("JSON.stringify(Object.keys(x))"));
 
@@ -2870,6 +2870,24 @@ namespace Jint.Tests.Runtime
             Assert.False(_engine.Evaluate("Object.prototype.hasOwnProperty.call(x, 'Third')").AsBoolean());
         }
 
+        [Fact]
+        public void CanConfigureCustomObjectTypeForJsToClrConversion()
+        {
+            var engine = new Engine(options =>
+            {
+                options.Interop.CreateClrObject = oi => new Dictionary<string, object>((int) oi.Length);
+            });
+
+            object capture = null;
+            var callback = (object value) => capture = value;
+            engine.SetValue("callback", callback);
+            engine.Evaluate("callback(({'a': 'b'}));");
+
+            Assert.IsType<Dictionary<string, object>>(capture);
+            var dictionary = (Dictionary<string, object>) capture;
+            Assert.Equal("b", dictionary["a"]);
+        }
+
         private class Profile
         {
             public int AnyProperty => throw new NotSupportedException("NOT SUPPORTED");

Jint/Native/Object/ObjectInstance.cs

@@ -982,7 +982,7 @@ namespace Jint.Native.Object
 
                 case ObjectClass.Arguments:
                 case ObjectClass.Object:
-                    IDictionary<string, object> o = new ExpandoObject();
+                    var o = _engine.Options.Interop.CreateClrObject(this);
                     foreach (var p in GetOwnProperties())
                     {
                         if (!p.Value.Enumerable)
@@ -991,7 +991,7 @@ namespace Jint.Native.Object
                         }
 
                         var key = p.Key.ToString();
-                        var propertyValue = Get(p.Key, this);
+                        var propertyValue = Get(p.Key);
                         var value = propertyValue is ObjectInstance oi
                             ? oi.ToObject(stack)
                             : propertyValue.ToObject();

Jint/Options.cs

@@ -285,6 +285,11 @@ namespace Jint
         /// Defaults to only coercing to string values when writing to string targets.
         /// </summary>
         public ValueCoercionType ValueCoercion { get; set; } = ValueCoercionType.String;
+
+        /// <summary>
+        /// Strategy to create a CLR object to hold converted <see cref="ObjectInstance"/>.
+        /// </summary>
+        public Func<ObjectInstance, IDictionary<string, object>> CreateClrObject = _ => new ExpandoObject();
     }
 
     /// <summary>