DSL Tools

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.VisualStudio.OLE.Interop;
using System.Runtime.InteropServices;
using Microsoft.VisualStudio.Shell;
using System.Diagnostics;
using EnvDTE;
using System.IO;

namespace Company.Smpl
{
    [Guid("D8760704-A993-40ee-89B9-FB77764D99AF")]
    public class SmplGenerator : IVsSingleFileGenerator, IObjectWithSite
    {
        private ServiceProvider _serviceProvider;
        private object _site;

        public string GetDefaultExtension()
        {
            return ".txt";
        }

        public virtual void SetSite(object site)
        {
            _site = site;
            _serviceProvider = null;
        }

        private ServiceProvider SiteServiceProvider
        {
            get
            {
                if (_serviceProvider == null)
                {
                    Microsoft.VisualStudio.OLE.Interop.IServiceProvider provider = _site as Microsoft.VisualStudio.OLE.Interop.IServiceProvider;
                    _serviceProvider = new ServiceProvider(provider);
                }
                return _serviceProvider;
            }
        }

        public virtual void GetSite(ref Guid riid, out IntPtr ppvSite)
        {
            if (_site == null)
            {
                throw new COMException("ObjectNotSited", -2147467259);
            }
            IntPtr ptr1 = Marshal.GetIUnknownForObject(_site);
            IntPtr ptr2 = IntPtr.Zero;
            Marshal.QueryInterface(ptr1, ref riid, out ptr2);
            if (ptr2 == IntPtr.Zero)
            {
                throw new COMException("SiteInterfaceNotSupported", -2147467262);
            }
            ppvSite = ptr2;
        }

        public void Generate(
            string inputFilePath,
            string inputFileContents,
            string defaultNamespace,
            out System.IntPtr outputFileContents,
            out int outputLength,
            IVsGeneratorProgress generateProgress)
        {
            ProjectItem item = SiteServiceProvider.GetService(typeof(EnvDTE.ProjectItem)) as ProjectItem;

            outputLength = 0;
            byte[] bytes = null;

            bytes = GenerateCode(inputFilePath, inputFileContents, item, out outputLength);

            if (bytes == null)
            {
                outputFileContents = IntPtr.Zero;
                outputLength = 0;
            }
            else
            {
                outputFileContents = Marshal.AllocCoTaskMem(outputLength);
                Marshal.Copy(bytes, 0, outputFileContents, outputLength);
            }
        }

        private byte[] GenerateCode(string inputFilePath, string inputFileContents, ProjectItem item, out int length)
        {
            using (MemoryStream ms = new MemoryStream())
            {
                using (StreamWriter writer = new StreamWriter(ms))
                {
                    writer.WriteLine("This line was generated by our SmplGenerator.");
                    writer.Flush();
                    length = (int)ms.Length;
                    return ms.GetBuffer();
                }
            }
            
        }
    }
}