1  public class Expression

 2     {

 3         object instance;

 4         MethodInfo method;

 5         /// <summary>

 6         /// 表达试运算

 7         /// </summary>

 8         /// <param name="expression">表达试</param>

 9         public Expression(string expression)

10         {

11             if (expression.IndexOf("return") < 0) expression = "return " + expression + ";";

12             string className = "Expression";

13             string methodName = "Compute";

14             CompilerParameters p = new CompilerParameters();

15             p.GenerateInMemory = true;

16             CompilerResults cr = new CSharpCodeProvider().CompileAssemblyFromSource(p, string.

17               Format("using System;sealed class {0}{{public double {1}(double x){{{2}}}}}",

18               className, methodName, expression));

19             if (cr.Errors.Count > 0)

20             {

21                 string msg = "Expression(\"" + expression + "\"): \n";

22                 foreach (CompilerError err in cr.Errors) msg += err.ToString() + "\n";

23                 throw new Exception(msg);

24             }

25             instance = cr.CompiledAssembly.CreateInstance(className);

26             method = instance.GetType().GetMethod(methodName);

27         }

28         /// <summary>

29         /// 处理数据

30         /// </summary>

31         /// <param name="x"></param>

32         /// <returns>返回计算值</returns>

33         public double Compute(double x)

34         {

35             return (double)method.Invoke(instance, new object[] { x });

36         }