VBCode in C# runtime compiling

最新推荐文章于 2024-06-18 20:39:22 发布

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#c# #parameters #null #object #exception #string

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本文介绍了一种使用CodeDom在运行时动态编译数学表达式的实现方法。通过Visual Basic Code Provider，将字符串形式的数学表达式编译为可执行代码，并提供了一个具体的类`FuncXYCodeDomHelper`来演示整个过程。

using System;
using System.CodeDom.Compiler;
using Microsoft.VisualBasic;
using System.Reflection;
using System.Text;

public class FuncXYCodeDomHelper
{
    Assembly assy;

  object execInstance;
  MethodInfo method;
  object[] parameters;

  public string expression;

  public FuncXYCodeDomHelper(string exp)
  {
       expression = exp;

        //Generate VB Code
        StringBuilder sb = new StringBuilder();
        //sb.Append("Imports System/r/n");
        sb.Append("Imports System.Math/r/n");
        sb.Append("Namespace RuntimeNamespace/r/n");
        sb.Append("Class RuntimeClass/r/n");
        sb.Append("Public Function f(ByVal x As Double, ByVal y As Double) As Double/r/n");
        sb.Append("Return " + this.expression + "/r/n");
        sb.Append("End Function/r/n");
        sb.Append("End Class/r/n");
        sb.Append("End Namespace/r/n");

      //Prepare CodeDom
        VBCodeProvider cp = new VBCodeProvider();
        CompilerParameters cparams = new CompilerParameters();
        cparams.GenerateInMemory = true;
        CompilerResults cresults = cp.CompileAssemblyFromSource(cparams, sb.ToString());

        sb=null;

        if(cresults.Errors.Count>0)
        {
            throw new Exception("Compile error count : " + cresults.Errors.Count.ToString());
        }
        else
        {
            assy = cresults.CompiledAssembly;
            execInstance = assy.CreateInstance("RuntimeNamespace.RuntimeClass");
            Type t = execInstance.GetType();
            method = t.GetMethod("f");
            parameters = new object[2];
        }
  }

  ~FuncXYCodeDomHelper()
  {
       method = null;
       parameters = null;
       execInstance = null;
       assy = null;
  }

  public double func(double x, double y)
  {
       parameters[0]=x;
       parameters[1]=y;
       return (double)method.Invoke(execInstance, parameters);
  }
}