MVC ---- Manager.ttinclude内容

http://www.infoq.com/cn/news/2009/11/T4-Multiple-Output

初次认识并尝试使用T4生成代码的时候，相关学习资料似乎比较少。不过现在VS2010 的MSDN里已有相关章节，可参看《代码生成和文本模板》章节。可以用C#的语法写模板，实在舒服很多。

很快就发现T4难以生成多个文件的缺陷，微软似乎也不着急改进这一点。通过搜索，从InfoQ找到一篇文章《用T4生成多个文件》，链接到一篇文章，Damien Guard的扩展可以方便的生成多个文件。原文是英文，能看懂，然而如果翻译则斟酌字词太辛苦。

首先，保存以下代码为一个模板文件(例如保存文件名为Manager.ttinclude)：

<#@ assembly name="System.Core"#>

<#@ assembly name="System.Data.Linq"#>

<#@ assembly name="EnvDTE"#>

<#@ assembly name="System.Xml"#>

<#@ assembly name="System.Xml.Linq"#>

<#@ import namespace="System"#>

<#@ import namespace="System.CodeDom"#>

<#@ import namespace="System.CodeDom.Compiler"#>

<#@ import namespace="System.Collections.Generic"#>

<#@ import namespace="System.Data.Linq"#>

<#@ import namespace="System.Data.Linq.Mapping"#>

<#@ import namespace="System.IO"#>

<#@ import namespace="System.Linq"#>

<#@ import namespace="System.Reflection"#>

<#@ import namespace="System.Text"#>

<#@ import namespace="System.Xml.Linq"#>

<#@ import namespace="Microsoft.VisualStudio.TextTemplating"#>

<#+  

// Manager class records the various blocks so it can split them up

class Manager {

    private class Block {

        public String Name;

        public int Start, Length;

    }  

    private Block currentBlock;

    private List<Block> files = new List<Block>();

    private Block footer = new Block();

    private Block header = new Block();

    private ITextTemplatingEngineHost host;

    private StringBuilder template;

    protected List<String> generatedFileNames = new List<String>();  

    public static Manager Create(ITextTemplatingEngineHost host, StringBuilder template) {

        return (host is IServiceProvider) ? new VSManager(host, template) : new Manager(host, template);

    }  

    public void StartNewFile(String name) {

        if (name == null)

            throw new ArgumentNullException("name");

        CurrentBlock = new Block { Name = name };

    }  

    public void StartFooter() {

        CurrentBlock = footer;

    }  

    public void StartHeader() {

        CurrentBlock = header;

    }  

    public void EndBlock() {

        if (CurrentBlock == null)

            return;

        CurrentBlock.Length = template.Length - CurrentBlock.Start;

        if (CurrentBlock != header && CurrentBlock != footer)

            files.Add(CurrentBlock);

        currentBlock = null;

    }  

    public virtual void Process(bool split) {

        if (split) {

            EndBlock();

            String headerText = template.ToString(header.Start, header.Length);

            String footerText = template.ToString(footer.Start, footer.Length);

            String outputPath = Path.GetDirectoryName(host.TemplateFile);

            files.Reverse();

            foreach(Block block in files) {

                String fileName = Path.Combine(outputPath, block.Name);

                String content = headerText + template.ToString(block.Start, block.Length) + footerText;

                generatedFileNames.Add(fileName);

                CreateFile(fileName, content);

                template.Remove(block.Start, block.Length);

            }

        }

    }  

    protected virtual void CreateFile(String fileName, String content) {

        if (IsFileContentDifferent(fileName, content))

            File.WriteAllText(fileName, content);

    }  

    public virtual String GetCustomToolNamespace(String fileName) {

        return null;

    }  

    public virtual String DefaultProjectNamespace {

        get { return null; }

    }  

    protected bool IsFileContentDifferent(String fileName, String newContent) {

        return !(File.Exists(fileName) && File.ReadAllText(fileName) == newContent);

    }  

    private Manager(ITextTemplatingEngineHost host, StringBuilder template) {

        this.host = host;

        this.template = template;

    }  

    private Block CurrentBlock {

        get { return currentBlock; }

        set {

            if (CurrentBlock != null)

                EndBlock();

            if (value != null)

                value.Start = template.Length;

            currentBlock = value;

        }

    }  

    private class VSManager: Manager {

        private EnvDTE.ProjectItem templateProjectItem;

        private EnvDTE.DTE dte;

        private Action<String> checkOutAction;

        private Action<IEnumerable<String>> projectSyncAction;  

        public override String DefaultProjectNamespace {

            get {

                return templateProjectItem.ContainingProject.Properties.Item("DefaultNamespace").Value.ToString();

            }

        }  

        public override String GetCustomToolNamespace(string fileName) {

            return dte.Solution.FindProjectItem(fileName).Properties.Item("CustomToolNamespace").Value.ToString();

        }  

        public override void Process(bool split) {

            if (templateProjectItem.ProjectItems == null)

                return;

            base.Process(split);

            projectSyncAction.EndInvoke(projectSyncAction.BeginInvoke(generatedFileNames, null, null));

        }  

        protected override void CreateFile(String fileName, String content) {

            if (IsFileContentDifferent(fileName, content)) {

                CheckoutFileIfRequired(fileName);

                File.WriteAllText(fileName, content);

            }

        }  

        internal VSManager(ITextTemplatingEngineHost host, StringBuilder template)

            : base(host, template) {

            var hostServiceProvider = (IServiceProvider) host;

            if (hostServiceProvider == null)

                throw new ArgumentNullException("Could not obtain IServiceProvider");

            dte = (EnvDTE.DTE) hostServiceProvider.GetService(typeof(EnvDTE.DTE));

            if (dte == null)

                throw new ArgumentNullException("Could not obtain DTE from host");

            templateProjectItem = dte.Solution.FindProjectItem(host.TemplateFile);

            checkOutAction = (String fileName) => dte.SourceControl.CheckOutItem(fileName);

            projectSyncAction = (IEnumerable<String> keepFileNames) => ProjectSync(templateProjectItem, keepFileNames);

        }  

        private static void ProjectSync(EnvDTE.ProjectItem templateProjectItem, IEnumerable<String> keepFileNames) {

            var keepFileNameSet = new HashSet<String>(keepFileNames);

            var projectFiles = new Dictionary<String, EnvDTE.ProjectItem>();

            var originalFilePrefix = Path.GetFileNameWithoutExtension(templateProjectItem.get_FileNames()) + ".";

            foreach(EnvDTE.ProjectItem projectItem in templateProjectItem.ProjectItems)

                projectFiles.Add(projectItem.get_FileNames(), projectItem);  

            // Remove unused items from the project

            foreach(var pair in projectFiles)

                if (!keepFileNames.Contains(pair.Key) && !(Path.GetFileNameWithoutExtension(pair.Key) + ".").StartsWith(originalFilePrefix))

                    pair.Value.Delete();  

            // Add missing files to the project

            foreach(String fileName in keepFileNameSet)

                if (!projectFiles.ContainsKey(fileName))

                    templateProjectItem.ProjectItems.AddFromFile(fileName);

        }  

        private void CheckoutFileIfRequired(String fileName) {

            var sc = dte.SourceControl;

            if (sc != null && sc.IsItemUnderSCC(fileName) && !sc.IsItemCheckedOut(fileName))

                checkOutAction.EndInvoke(checkOutAction.BeginInvoke(fileName, null, null));

        }

    }

} #>

接着，在T4模板文件里引用这个模板，并声明一个Manager类实例，使用例子：

<#@ template language="C#" hostspecific="True"#>

<#@include file="Manager.ttinclude"#>

<# var manager = Manager.Create(Host, GenerationEnvironment); #>

使用两行代码可使代码输出到单独文件，你要输出的代码可写在这两个语句中间，StartNewFile的参数就是输出的文件名：

<# manager.StartNewFile("Employee.generated.cs"); #>  

<# manager.EndBlock(); #>

比如可以这样写：

<# manager.StartNewFile("Employee.generated.cs"); #>

public class Employee {  }

<# manager.EndBlock(); #>

还可以为每个输出文件输出同样的头部或顶部，只需要相应的语句：

<# manager.StartHeader(); #>

// Code generated by a template

using System;

<# manager.EndBlock(); #>  

<# manager.StartFooter(); #>

// It's the end

<# manager.EndBlock(); #>

最后使用这句来执行输出多个文件：

<# manager.Process(true); #>

巴特西

MVC ---- Manager.ttinclude内容

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