C# 编译JS -Evaluator

忘记哪里转过来的，自己mark一下

//// <summary>
/// 动态求值
/// </summary>
public class Evaluator
{
/// <summary>
/// 计算结果,如果表达式出错则抛出异常
/// </summary>
/// <param name="statement">表达式,如"1+2+3+4"</param>
/// <returns>结果</returns>
public static object Eval(string statement)
{
return _evaluatorType.InvokeMember("Eval", BindingFlags.InvokeMethod, null, _evaluator, new object[] { statement });
}
static Evaluator()
{
//构造JScript的编译驱动代码
CodeDomProvider provider = CodeDomProvider.CreateProvider("JScript");

CompilerParameters parameters;
parameters = new CompilerParameters();
parameters.GenerateInMemory = true;

CompilerResults results;
results = provider.CompileAssemblyFromSource(parameters, _jscriptSource);

Assembly assembly = results.CompiledAssembly;
_evaluatorType = assembly.GetType("Evaluator");

_evaluator = Activator.CreateInstance(_evaluatorType);
}

private static object _evaluator = null;
private static Type _evaluatorType = null;
//// <summary>
/// JScript代码
/// </summary>
private static readonly string _jscriptSource =

@"class Evaluator
{
public function Eval(expr : String) : String 
{ 
return eval(expr); 
}
}";
}