UnaryOperationBinder.cs

using System.Dynamic.Utils;
using System.Linq.Expressions;

namespace System.Dynamic
{
    [global::__DynamicallyInvokable]
    public abstract class UnaryOperationBinder : DynamicMetaObjectBinder
    {
        private ExpressionType _operation;

        [global::__DynamicallyInvokable]
        public sealed override Type ReturnType
        {
            [global::__DynamicallyInvokable]
            get
            {
                ExpressionType operation = _operation;
                if (operation == ExpressionType.IsTrue || operation == ExpressionType.IsFalse)
                {
                    return typeof(bool);
                }
                return typeof(object);
            }
        }

        [global::__DynamicallyInvokable]
        public ExpressionType Operation
        {
            [global::__DynamicallyInvokable]
            get
            {
                return _operation;
            }
        }

        internal sealed override bool IsStandardBinder => true;

        [global::__DynamicallyInvokable]
        protected UnaryOperationBinder(ExpressionType operation)
        {
            ContractUtils.Requires(OperationIsValid(operation), "operation");
            _operation = operation;
        }

        [global::__DynamicallyInvokable]
        public DynamicMetaObject FallbackUnaryOperation(DynamicMetaObject target)
        {
            return FallbackUnaryOperation(target, null);
        }

        [global::__DynamicallyInvokable]
        public abstract DynamicMetaObject FallbackUnaryOperation(DynamicMetaObject target, DynamicMetaObject errorSuggestion);

        [global::__DynamicallyInvokable]
        public sealed override DynamicMetaObject Bind(DynamicMetaObject target, DynamicMetaObject[] args)
        {
            ContractUtils.RequiresNotNull(target, "target");
            ContractUtils.Requires(args == null || args.Length == 0, "args");
            return target.BindUnaryOperation(this);
        }

        internal static bool OperationIsValid(ExpressionType operation)
        {
            switch (operation)
            {
            case ExpressionType.Negate:
            case ExpressionType.UnaryPlus:
            case ExpressionType.Not:
            case ExpressionType.Decrement:
            case ExpressionType.Extension:
            case ExpressionType.Increment:
            case ExpressionType.OnesComplement:
            case ExpressionType.IsTrue:
            case ExpressionType.IsFalse:
                return true;
            default:
                return false;
            }
        }
    }
}