using EC.Helper.RabbitFunc.Expressions;
using EC.Helper.RabbitFunc.Runtime;

namespace EC.Helper.RabbitFunc.Extern;

[ExternLambda]
internal class ExpLambdaExpression : SystemLambdaExpression
{
    public ExpLambdaExpression()
        : base(typeof(Math).GetMethod(nameof(Math.Exp), new Type[] { typeof(double) }), "exp", new BodyExpression(),
              Expression.Parameter(typeof(double), "x"))
    { }

    private class BodyExpression : Expression
    {
        public override object Eval(RuntimeContext context)
        {
            return Math.Exp(ParameterExpression.Access<double>(context, "x"));
        }
    }
}