A tool for dynamic compile and run of C# or VB.NET code

• Download demo project - 7 Kb
• Download source - 9 Kb

Introduction

This program compiles a piece of code in memory and runs it dynamically, so you can test some C# or VB.NET code without having to create a new project or solution.

Background

Very often, we need test a piece of code ( C# or VB.NET ). In .NET environment, we use "csc" or "vbc" command; In VS.NET, we create a new project or solution, and create many other files. Both of them are tedious, especially when we test a simple program. One way is produced by jconwell, "Dot Net Script". He uses XML files ( named "dnml" ) which include C# or VB code. In that method, a dnml file is parsed and the code is compiled in memory. That's a good idea! However, it is a little inconvenience because it needs to build a new file. Here we provide a tool based on his work. The tool has these characters:

• It can load C# or VB code file, compile the code in memory, and run the code through a static method ( "entry point" );
• As for VB.NET code, if it is a "Form", the tool can add "Main()" to run the form;
• It uses a new thread to run the code;
• It has a visual interface( see blow ).

Using the tool

As the picture blow shows, press button "Open..." can Open C# or VB.NET file; press button "Paste" to paste code from clipboard to text area; check box "C#" means if the code is C# language; the text box is filled with entry point ( a static method in C# or a shared Sub or Function in VB.NET ); press button "Run!" to compile and run the code.

How it woks

The main class of the program is CompileEngine, which has such a constructor

  public CompileEngine( string code, LanguageType language, string 

entry )
  {
   this.SourceCode = code;
   this.Language = language;
   this.EntryPoint = entry;
  }

Run is an important method. It includes three steps: PrepareRealSourceCode, CreateAssembly and CallEntry.

  public void Run()
  {
   ClearErrMsgs();

   string strRealSourceCode = PrepareRealSourceCode();

   Assembly assembly = CreateAssembly( strRealSourceCode );

   CallEntry( assembly, EntryPoint );

   DisplayErrorMsg();

  }

PrepareRealSourceCode has two functions: to add "Imports" statements and to add "Sub Main" for VB.NET Windows Forms.

  private string PrepareRealSourceCode()
  {
   
   string strRealSourceCode = "";

   // add some using(Imports) statements

   string strUsingStatement = "";
   
   if( Language == LanguageType.VB )
   {
    string [] basicImportsStatement = {
       "Imports Microsoft.VisualBasic",
       "Imports System",
       "Imports System.Windows.Forms",
       "Imports System.Drawing",
       "Imports System.Data",
       "Imports System.Threading",
       "Imports System.Xml",
       "Imports System.Collections",
       "Imports System.Diagnostics",      
    };
    foreach( string si in basicImportsStatement )
    {
     if( SourceCode.IndexOf( si ) < 0 )
      strUsingStatement += si + "\r\n";
    }
   }

   strRealSourceCode = strUsingStatement + SourceCode;

    // for VB Prog, Add Main(), So We Can Run It

   if( Language == LanguageType.VB && EntryPoint == "Main" &&
    strRealSourceCode.IndexOf( "Sub Main(") < 0 ) 
   {
    try
    {
     int posClass = strRealSourceCode.IndexOf( "Public Class ")+ 
        "Public Class ".Length;
     int posClassEnd = strRealSourceCode.IndexOf( "\r\n", posClass );
     string className = strRealSourceCode.Substring( posClass, 
          posClassEnd - posClass );
     int pos = strRealSourceCode.LastIndexOf( "End Class");
     if( pos > 0 )
      strRealSourceCode = strRealSourceCode.Substring( 0, pos ) + @"
          Private Shared Sub Main()
           " + "Dim frm As New " + className + "()" + @"
                   If TypeOf frm Is Form Then frm.ShowDialog()
          End Sub
         " + strRealSourceCode.Substring( pos );
    }
    catch{}
   }

   return strRealSourceCode;

  }

  
        // compile the source, and create assembly in memory

        // this method code is mainly from jconwell, 

        // see http://www.codeproject.com/dotnet/DotNetScript.asp

        private Assembly CreateAssembly(string strRealSourceCode)
        {
            //Create an instance whichever code provider that is needed

            CodeDomProvider codeProvider = null;
            if (Language == LanguageType.CSharp )
                codeProvider = new CSharpCodeProvider();
            else if( Language == LanguageType.VB )
                codeProvider = new VBCodeProvider();

            //create the language specific code compiler

            ICodeCompiler compiler = codeProvider.CreateCompiler();

            //add compiler parameters

            CompilerParameters compilerParams = new CompilerParameters();
            compilerParams.CompilerOptions = "/target:library"; 
                   // you can add /optimize

            compilerParams.GenerateExecutable = false;
            compilerParams.GenerateInMemory = true;            
            compilerParams.IncludeDebugInformation = false;

            // add some basic references

            compilerParams.ReferencedAssemblies.Add( "mscorlib.dll");
            compilerParams.ReferencedAssemblies.Add( "System.dll");            
            compilerParams.ReferencedAssemblies.Add( "System.Data.dll" );
            compilerParams.ReferencedAssemblies.Add( "System.Drawing.dll" );
            compilerParams.ReferencedAssemblies.Add( "System.Xml.dll" );
            compilerParams.ReferencedAssemblies.Add( 
                  "System.Windows.Forms.dll" );

            if( Language == LanguageType.VB )
            {
                compilerParams.ReferencedAssemblies.Add( 
                      "Microsoft.VisualBasic.dll" );
            }

            //actually compile the code

            CompilerResults results = compiler.CompileAssemblyFromSource(
                    compilerParams, 
                    strRealSourceCode );

            //get a hold of the actual assembly that was generated

            Assembly generatedAssembly = results.CompiledAssembly;

            //return the assembly

            return generatedAssembly;
        }

CallEntry(Assembly...) is used for call entrypoint by reflection.

  
    // invoke the entry method

    // this method code is mainly from jconwell, 

    // see http://www.codeproject.com/dotnet/DotNetScript.asp

        private void CallEntry(Assembly assembly, string entryPoint)
        {
            try
            {
                //Use reflection to call the static Main function

                Module[] mods = assembly.GetModules(false);
                Type[] types = mods[0].GetTypes();

                foreach (Type type in types)
                {
                    MethodInfo mi = type.GetMethod(entryPoint, 
                            BindingFlags.Public | BindingFlags.NonPublic 

| BindingFlags.Static);  
                    if (mi != null)
                    {
                        if( mi.GetParameters().Length == 1 )  
                        {
                            if( 

mi.GetParameters()[0].ParameterType.IsArray )
                            {
                                string [] par = new string[1]; // if 


Main has string [] arguments
                                 mi.Invoke(null, par);
                            }
                        }
                        else
                        {
                            mi.Invoke(null, null);
                        }
                        return;
                    }
                }
            }
            catch (Exception ex)
            {
            }
        }

In the FormMain, make a new thread to make a CompileEngine instance and call Run.

         
  private void btnRun_Click(object sender, System.EventArgs e)
  {
   // we use a new thread to run it

   new Thread( new ThreadStart( RunTheProg ) ).Start();
  }

  private void RunTheProg()
  {
   string code = txtSource.Text.Trim();
   LanguageType language = chkIsCSharp.Checked ? 
      LanguageType.CSharp : LanguageType.VB;
   string entry = txtEntry.Text.Trim();

   if( code == "" ) return;
   if( entry == "" ) entry = "Main";

   CompileEngine engine = new CompileEngine( code, language, entry );

   engine.Run();
  }

Some things that can improve

In the PrepareRealSourceCode, it better to use regular expressions to find class name.

Acknowledgement

Thanks jconwell, VictorV, George Orwell, Eric Astor and other friends, they show me many excellent works on this topic, such as Dot Net Script, SnippetCompiler, Runtime Compilation.