using System;

using System.CodeDom.Compiler;

using System.Reflection;

using System.Web.UI;

using Microsoft.JScript;

namespace HuaTong.General.Utility

{

    /// <summary>

    /// JScriptProvider包装

    /// </summary>

    public static class JScript

    {

        private static object js = null;

        private static Type jsType = null;

        private static readonly string jsSource =

          @"package JScript

          {

             class JScript

             {

              public function Eval(expr : String) : Object

              {

               return eval(expr);

              }

             }

          }";

        /// <summary>

        /// 构造javascript运行时对象

        /// </summary>

        static JScript()

        {

            JScriptCodeProvider compiler = new JScriptCodeProvider();

            CompilerParameters parameters = new CompilerParameters();

            parameters.GenerateInMemory = true;

            CompilerResults results = compiler.CompileAssemblyFromSource(parameters, jsSource);

            Assembly assembly = results.CompiledAssembly;

            jsType = assembly.GetType("JScript.JScript");

            js = Activator.CreateInstance(jsType);

        }

        /// <summary>

        /// 获取表达式的值

        /// </summary>

        /// <returns></returns>

        public static int EvalToInt32(string code)

        {

            string s = EvalToString(code);

            return int.Parse(s);

        }

        /// <summary>

        /// 获取表达式的值

        /// </summary>

        /// <returns></returns>

        public static double EvalToDouble(string code)

        {

            string s = EvalToString(code);

            return double.Parse(s);

        }

        /// <summary>

        /// 获取表达式的值

        /// </summary>

        /// <returns></returns>

        public static string EvalToString(string code)

        {

            object o = EvalToObject(code);

            return o.ToString();

        }

        /// <summary>

        /// 获取表达式的值

        /// </summary>

        /// <returns></returns>

        public static object EvalToObject(string code)

        {

            return jsType.InvokeMember("Eval", BindingFlags.InvokeMethod, null, js,

                  new object[] { code });

        }

    }

}