/*
动态编译类，可以计算表达式，也可以调用系统中的类
调用方式： return new XXXXXXX.Eval().GetValue('System.DateTime.Now')
返回结果： 2005-08-04 15:00:24
*/
using System;
using System.CodeDom;
using System.CodeDom.Compiler;
using Microsoft.CSharp;
using System.Reflection;
using System.IO;
namespace XXXXXXX
{
/*****************************************************************
** 文件名: Eval.cs
** Copyright (c) 1999 -2003
** 创建人: Phoenix
** 创建日期:
** 修改人: BigmouthZ@163.net
** 修改日期: 2005/08/04
** 描 述: 获取字符串所表示的逻辑意义
** 版 本:1.0
******************************************************************/
public class Eval
{
public object GetValue( string value )
{
string codeSnippet =
@'
using System;
using System.Collections;
using DBCore;
namespace CzG
{
public class $0$
{
public $0$(){}
public object GetValue()
{
return $1$ ;
}
}
}';
string tmp = 'Eval' + Convert.ToString(System.DateTime.Now.Ticks);
codeSnippet = codeSnippet.Replace('$0$',tmp);
codeSnippet = codeSnippet.Replace('$1$',value);
object b = '';
try
{
ICodeCompiler compiler = new CSharpCodeProvider().CreateCompiler();
CompilerParameters para = new CompilerParameters();
para.ReferencedAssemblies.Add( 'System.dll' );
string path = System.Environment.CurrentDirectory;
para.ReferencedAssemblies.Add( path + @'\DBCore.dll' );
para.GenerateInMemory = true;
para.GenerateExecutable = false;
para.OutputAssembly = path + '\\' + tmp + '.dll';
CompilerResults cr = compiler.CompileAssemblyFromSource(para, codeSnippet);
Assembly asm = cr.CompiledAssembly;
object obj = asm.CreateInstance( 'CzG.' + tmp );
Type type = asm.GetType( 'CzG.' + tmp );
MethodInfo mi = type.GetMethod('GetValue');
b = mi.Invoke( obj , null );
GC.Collect();
System.IO.File.Delete( path + '\\' + tmp + '.dll');
}
catch
{
b = 'CallError!';
}
return b;
}
}
}