sebastienros.jint/Jint/Runtime/Interop/Reflection/ConstantValueAccessor.cs

using System;
using Jint.Native;
using Jint.Runtime.Descriptors;

namespace Jint.Runtime.Interop.Reflection
{
    internal sealed class ConstantValueAccessor : ReflectionAccessor
    {
        public static readonly ConstantValueAccessor NullAccessor = new(null);

        public ConstantValueAccessor(JsValue value) : base(null, null)
        {
            ConstantValue = value;
        }

        public override bool Writable => false;

        protected override JsValue ConstantValue { get; }

        protected override object DoGetValue(object target)
        {
            return ConstantValue;
        }

        protected override void DoSetValue(object target, object value)
        {
            throw new InvalidOperationException();
        }

        public override PropertyDescriptor CreatePropertyDescriptor(Engine engine, object target)
        {
            return ConstantValue is null 
                ? PropertyDescriptor.Undefined 
                : new(ConstantValue, PropertyFlag.AllForbidden);
        }
    }
}