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

namespace EC.Helper.RabbitFunc.Extern;

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

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