UnaryOperationBinder.cs

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using System.Dynamic.Utils;
using System.Linq.Expressions;
 
namespace System.Dynamic;
 
public abstract class UnaryOperationBinder : DynamicMetaObjectBinder
{
    public sealed override Type ReturnType
    {
        get
        {
            ExpressionType operation = Operation;
            if ((uint)(operation - 83) <= 1u)
            {
                return typeof(bool);
            }
            return typeof(object);
        }
    }
 
    public ExpressionType Operation { get; }
 
    internal sealed override bool IsStandardBinder => true;
 
    protected UnaryOperationBinder(ExpressionType operation)
    {
        ContractUtils.Requires(OperationIsValid(operation), "operation");
        Operation = operation;
    }
 
    public DynamicMetaObject FallbackUnaryOperation(DynamicMetaObject target)
    {
        return FallbackUnaryOperation(target, null);
    }
 
    public abstract DynamicMetaObject FallbackUnaryOperation(DynamicMetaObject target, DynamicMetaObject? errorSuggestion);
 
    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;
        }
    }
}