从T4模板引擎到自己的代码生成器(1)
Ｔ４模板才接触半个月，但最不满的是它不能方便的脱离vs stuido。如果我要自己写代码生成器，怎么办？
园子里讲T4模板的不少，但讲如何在自己的程序中使用引擎的很少。查了很久的资料才知道，这东西叫：Text Template Host.
知道名字，资料就好了。接下来就可以试着建立一个自己的Host.
(1)写一个最简单的tt文件：
<#@ template debug="true" hostSpecific="true" #>
<#@ output extension=".cs" #>
using System;public class HelloWord{
static void Main() {
}
}
<#@ output extension=".cs" #>
using System;public class HelloWord{
static void Main() {
}
}
(２)新建一个项目，放个按钮，写点击代码：
TextCode host = new TextCode();
//host.Namespace = txtNamespace.Text;
//host.Classname = txtTablemame.Text;
host.FileExtension = ".cs";
host.TemplateFile = "Test.tt";
Microsoft.VisualStudio.TextTemplating.Engine engine = new Microsoft.VisualStudio.TextTemplating.Engine();
string content = "";
string input = "";
string output = "";
input = System.IO.File.ReadAllText(host.TemplateFile);
output = engine.ProcessTemplate(input, host);
string outputname ="newTest" + host.FileExtension;
System.IO.File.WriteAllText(outputname, output);
string strError="";
foreach (CompilerError error in host.Errors)
{
strError += error.ToString();
}
MessageBox.Show(strError);
//host.Namespace = txtNamespace.Text;
//host.Classname = txtTablemame.Text;
host.FileExtension = ".cs";
host.TemplateFile = "Test.tt";
Microsoft.VisualStudio.TextTemplating.Engine engine = new Microsoft.VisualStudio.TextTemplating.Engine();
string content = "";
string input = "";
string output = "";
input = System.IO.File.ReadAllText(host.TemplateFile);
output = engine.ProcessTemplate(input, host);
string outputname ="newTest" + host.FileExtension;
System.IO.File.WriteAllText(outputname, output);
string strError="";
foreach (CompilerError error in host.Errors)
{
strError += error.ToString();
}
MessageBox.Show(strError);
等等，一堆错误。。。那个TextCode 是什么东西？
(3) TextCode是自己写的一个类，它就是一个 host,需要实现一个TextTemplating.ITextTemplatingEngineHost接口。这个接口非常复杂，我找了一个比较完整的代码来解释。
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Xml;
using System.Data;
using System.CodeDom.Compiler;
namespace TestForT4.Code
{
[Serializable]
class TextCode : Microsoft.VisualStudio.TextTemplating.ITextTemplatingEngineHost
{
//the path and file name of the text template that is being processed
//---------------------------------------------------------------------
internal string TemplateFileValue;
public string TemplateFile
{
get { return TemplateFileValue; }
}
//This will be the extension of the generated text output file.
//The host can provide a default by setting the value of the field here.
//The engine can change this value based on the optional output directive
//if the user specifies it in the text template.
//---------------------------------------------------------------------
private string fileExtensionValue = ".txt";
public string FileExtension
{
get { return fileExtensionValue; }
}
//This will be the encoding of the generated text output file.
//The host can provide a default by setting the value of the field here.
//The engine can change this value based on the optional output directive
//if the user specifies it in the text template.
//---------------------------------------------------------------------
private Encoding fileEncodingValue = Encoding.UTF8;
public Encoding FileEncoding
{
get { return fileEncodingValue; }
}
//These are the errors that occur when the engine processes a template.
//The engine passes the errors to the host when it is done processing,
//and the host can decide how to display them. For example, the host
//can display the errors in the UI or write them to a file.
//---------------------------------------------------------------------
private CompilerErrorCollection errorsValue;
public CompilerErrorCollection Errors
{
get { return errorsValue; }
}
//The host can provide standard assembly references.
//The engine will use these references when compiling and
//executing the generated transformation class.
//--------------------------------------------------------------
public IList<string> StandardAssemblyReferences
{
get
{
return new string[]
{
//If this host searches standard paths and the GAC,
//we can specify the assembly name like this.
//---------------------------------------------------------
//"System"
//Because this host only resolves assemblies from the
//fully qualified path and name of the assembly,
//this is a quick way to get the code to give us the
//fully qualified path and name of the System assembly.
//---------------------------------------------------------
typeof(System.Uri).Assembly.Location
};
}
}
//The host can provide standard imports or using statements.
//The engine will add these statements to the generated
//transformation class.
//--------------------------------------------------------------
public IList<string> StandardImports
{
get
{
return new string[]
{
"System"
};
}
}
//The engine calls this method based on the optional include directive
//if the user has specified it in the text template.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
//The included text is returned in the context parameter.
//If the host searches the registry for the location of include files,
//or if the host searches multiple locations by default, the host can
//return the final path of the include file in the location parameter.
//---------------------------------------------------------------------
public bool LoadIncludeText(string requestFileName, out string content, out string location)
{
content = System.String.Empty;
location = System.String.Empty;
//If the argument is the fully qualified path of an existing file,
//then we are done.
//----------------------------------------------------------------
if (File.Exists(requestFileName))
{
content = File.ReadAllText(requestFileName);
return true;
}
//This can be customized to search specific paths for the file.
//This can be customized to accept paths to search as command line
//arguments.
//----------------------------------------------------------------
else
{
return false;
}
}
//Passes in the name of a service. If you have that service, you need to
//pass back a pointer to it. Otherwise, you need to pass back NULL to
//indicate that you have no knowledge of that service.
//--------------------------------------------------------------------
public object GetHostOption(string optionName)
{
object returnObject;
switch (optionName)
{
case "CacheAssemblies":
returnObject = true;
break;
default:
returnObject = null;
break;
}
return returnObject;
}
//The engine calls this method to resolve assembly references used in
//the generated transformation class project and for the optional
//assembly directive if the user has specified it in the text template.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
public string ResolveAssemblyReference(string assemblyReference)
{
//If the argument is the fully qualified path of an existing file,
//then we are done. (This does not do any work.)
//----------------------------------------------------------------
if (File.Exists(assemblyReference))
{
return assemblyReference;
}
//Maybe the assembly is in the same folder as the text template that
//called the directive.
//----------------------------------------------------------------
string candidate = Path.Combine(Path.GetDirectoryName(this.TemplateFile), assemblyReference);
if (File.Exists(candidate))
{
return candidate;
}
//This can be customized to search specific paths for the file
//or to search the GAC.
//----------------------------------------------------------------
//This can be customized to accept paths to search as command line
//arguments.
//----------------------------------------------------------------
//If we cannot do better, return the original file name.
return "";
}
//The engine calls this method based on the directives the user has
//specified in the text template.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
public Type ResolveDirectiveProcessor(string processorName)
{
//This host will not resolve any specific processors.
//Check the processor name, and if it is the name of a processor the
//host wants to support, return the type of the processor.
//---------------------------------------------------------------------
if (string.Compare(processorName, "XYZ", StringComparison.OrdinalIgnoreCase) == 0)
{
//return typeof();
}
//This can be customized to search specific paths for the file
//or to search the GAC
//If the directive processor cannot be found, throw an error.
throw new Exception("Directive Processor not found");
}
//A directive processor can call this method if a file name does not
//have a path.
//The host can attempt to provide path information by searching
//specific paths for the file and returning the file and path if found.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
public string ResolvePath(string fileName)
{
if (fileName == null)
{
throw new ArgumentNullException("the file name cannot be null");
}
//If the argument is the fully qualified path of an existing file,
//then we are done
//----------------------------------------------------------------
if (File.Exists(fileName))
{
return fileName;
}
//Maybe the file is in the same folder as the text template that
//called the directive.
//----------------------------------------------------------------
string candidate = Path.Combine(Path.GetDirectoryName(this.TemplateFile), fileName);
if (File.Exists(candidate))
{
return candidate;
}
//Look more places.
//----------------------------------------------------------------
//More code can go here...
//If we cannot do better, return the original file name.
return fileName;
}
//If a call to a directive in a text template does not provide a value
//for a required parameter, the directive processor can try to get it
//from the host by calling this method.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
public string ResolveParameterValue(string directiveId, string processorName, string parameterName)
{
if (directiveId == null)
{
throw new ArgumentNullException("the directiveId cannot be null");
}
if (processorName == null)
{
throw new ArgumentNullException("the processorName cannot be null");
}
if (parameterName == null)
{
throw new ArgumentNullException("the parameterName cannot be null");
}
//Code to provide "hard-coded" parameter values goes here.
//This code depends on the directive processors this host will interact with.
//If we cannot do better, return the empty string.
return String.Empty;
}
//The engine calls this method to change the extension of the
//generated text output file based on the optional output directive
//if the user specifies it in the text template.
//---------------------------------------------------------------------
public void SetFileExtension(string extension)
{
//The parameter extension has a '.' in front of it already.
//--------------------------------------------------------
fileExtensionValue = extension;
}
//The engine calls this method to change the encoding of the
//generated text output file based on the optional output directive
//if the user specifies it in the text template.
//----------------------------------------------------------------------
public void SetOutputEncoding(System.Text.Encoding encoding, bool fromOutputDirective)
{
fileEncodingValue = encoding;
}
//The engine calls this method when it is done processing a text
//template to pass any errors that occurred to the host.
//The host can decide how to display them.
//---------------------------------------------------------------------
public void LogErrors(CompilerErrorCollection errors)
{
errorsValue = errors;
}
//This is the application domain that is used to compile and run
//the generated transformation class to create the generated text output.
//----------------------------------------------------------------------
public AppDomain ProvideTemplatingAppDomain(string content)
{
//This host will provide a new application domain each time the
//engine processes a text template.
//-------------------------------------------------------------
return AppDomain.CreateDomain("Generation App Domain");
//This could be changed to return the current appdomain, but new
//assemblies are loaded into this AppDomain on a regular basis.
//If the AppDomain lasts too long, it will grow indefintely,
//which might be regarded as a leak.
//This could be customized to cache the application domain for
//a certain number of text template generations (for example, 10).
//This could be customized based on the contents of the text
//template, which are provided as a parameter for that purpose.
}
}
}
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Xml;
using System.Data;
using System.CodeDom.Compiler;
namespace TestForT4.Code
{
[Serializable]
class TextCode : Microsoft.VisualStudio.TextTemplating.ITextTemplatingEngineHost
{
//the path and file name of the text template that is being processed
//---------------------------------------------------------------------
internal string TemplateFileValue;
public string TemplateFile
{
get { return TemplateFileValue; }
}
//This will be the extension of the generated text output file.
//The host can provide a default by setting the value of the field here.
//The engine can change this value based on the optional output directive
//if the user specifies it in the text template.
//---------------------------------------------------------------------
private string fileExtensionValue = ".txt";
public string FileExtension
{
get { return fileExtensionValue; }
}
//This will be the encoding of the generated text output file.
//The host can provide a default by setting the value of the field here.
//The engine can change this value based on the optional output directive
//if the user specifies it in the text template.
//---------------------------------------------------------------------
private Encoding fileEncodingValue = Encoding.UTF8;
public Encoding FileEncoding
{
get { return fileEncodingValue; }
}
//These are the errors that occur when the engine processes a template.
//The engine passes the errors to the host when it is done processing,
//and the host can decide how to display them. For example, the host
//can display the errors in the UI or write them to a file.
//---------------------------------------------------------------------
private CompilerErrorCollection errorsValue;
public CompilerErrorCollection Errors
{
get { return errorsValue; }
}
//The host can provide standard assembly references.
//The engine will use these references when compiling and
//executing the generated transformation class.
//--------------------------------------------------------------
public IList<string> StandardAssemblyReferences
{
get
{
return new string[]
{
//If this host searches standard paths and the GAC,
//we can specify the assembly name like this.
//---------------------------------------------------------
//"System"
//Because this host only resolves assemblies from the
//fully qualified path and name of the assembly,
//this is a quick way to get the code to give us the
//fully qualified path and name of the System assembly.
//---------------------------------------------------------
typeof(System.Uri).Assembly.Location
};
}
}
//The host can provide standard imports or using statements.
//The engine will add these statements to the generated
//transformation class.
//--------------------------------------------------------------
public IList<string> StandardImports
{
get
{
return new string[]
{
"System"
};
}
}
//The engine calls this method based on the optional include directive
//if the user has specified it in the text template.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
//The included text is returned in the context parameter.
//If the host searches the registry for the location of include files,
//or if the host searches multiple locations by default, the host can
//return the final path of the include file in the location parameter.
//---------------------------------------------------------------------
public bool LoadIncludeText(string requestFileName, out string content, out string location)
{
content = System.String.Empty;
location = System.String.Empty;
//If the argument is the fully qualified path of an existing file,
//then we are done.
//----------------------------------------------------------------
if (File.Exists(requestFileName))
{
content = File.ReadAllText(requestFileName);
return true;
}
//This can be customized to search specific paths for the file.
//This can be customized to accept paths to search as command line
//arguments.
//----------------------------------------------------------------
else
{
return false;
}
}
//Passes in the name of a service. If you have that service, you need to
//pass back a pointer to it. Otherwise, you need to pass back NULL to
//indicate that you have no knowledge of that service.
//--------------------------------------------------------------------
public object GetHostOption(string optionName)
{
object returnObject;
switch (optionName)
{
case "CacheAssemblies":
returnObject = true;
break;
default:
returnObject = null;
break;
}
return returnObject;
}
//The engine calls this method to resolve assembly references used in
//the generated transformation class project and for the optional
//assembly directive if the user has specified it in the text template.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
public string ResolveAssemblyReference(string assemblyReference)
{
//If the argument is the fully qualified path of an existing file,
//then we are done. (This does not do any work.)
//----------------------------------------------------------------
if (File.Exists(assemblyReference))
{
return assemblyReference;
}
//Maybe the assembly is in the same folder as the text template that
//called the directive.
//----------------------------------------------------------------
string candidate = Path.Combine(Path.GetDirectoryName(this.TemplateFile), assemblyReference);
if (File.Exists(candidate))
{
return candidate;
}
//This can be customized to search specific paths for the file
//or to search the GAC.
//----------------------------------------------------------------
//This can be customized to accept paths to search as command line
//arguments.
//----------------------------------------------------------------
//If we cannot do better, return the original file name.
return "";
}
//The engine calls this method based on the directives the user has
//specified in the text template.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
public Type ResolveDirectiveProcessor(string processorName)
{
//This host will not resolve any specific processors.
//Check the processor name, and if it is the name of a processor the
//host wants to support, return the type of the processor.
//---------------------------------------------------------------------
if (string.Compare(processorName, "XYZ", StringComparison.OrdinalIgnoreCase) == 0)
{
//return typeof();
}
//This can be customized to search specific paths for the file
//or to search the GAC
//If the directive processor cannot be found, throw an error.
throw new Exception("Directive Processor not found");
}
//A directive processor can call this method if a file name does not
//have a path.
//The host can attempt to provide path information by searching
//specific paths for the file and returning the file and path if found.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
public string ResolvePath(string fileName)
{
if (fileName == null)
{
throw new ArgumentNullException("the file name cannot be null");
}
//If the argument is the fully qualified path of an existing file,
//then we are done
//----------------------------------------------------------------
if (File.Exists(fileName))
{
return fileName;
}
//Maybe the file is in the same folder as the text template that
//called the directive.
//----------------------------------------------------------------
string candidate = Path.Combine(Path.GetDirectoryName(this.TemplateFile), fileName);
if (File.Exists(candidate))
{
return candidate;
}
//Look more places.
//----------------------------------------------------------------
//More code can go here...
//If we cannot do better, return the original file name.
return fileName;
}
//If a call to a directive in a text template does not provide a value
//for a required parameter, the directive processor can try to get it
//from the host by calling this method.
//This method can be called 0, 1, or more times.
//---------------------------------------------------------------------
public string ResolveParameterValue(string directiveId, string processorName, string parameterName)
{
if (directiveId == null)
{
throw new ArgumentNullException("the directiveId cannot be null");
}
if (processorName == null)
{
throw new ArgumentNullException("the processorName cannot be null");
}
if (parameterName == null)
{
throw new ArgumentNullException("the parameterName cannot be null");
}
//Code to provide "hard-coded" parameter values goes here.
//This code depends on the directive processors this host will interact with.
//If we cannot do better, return the empty string.
return String.Empty;
}
//The engine calls this method to change the extension of the
//generated text output file based on the optional output directive
//if the user specifies it in the text template.
//---------------------------------------------------------------------
public void SetFileExtension(string extension)
{
//The parameter extension has a '.' in front of it already.
//--------------------------------------------------------
fileExtensionValue = extension;
}
//The engine calls this method to change the encoding of the
//generated text output file based on the optional output directive
//if the user specifies it in the text template.
//----------------------------------------------------------------------
public void SetOutputEncoding(System.Text.Encoding encoding, bool fromOutputDirective)
{
fileEncodingValue = encoding;
}
//The engine calls this method when it is done processing a text
//template to pass any errors that occurred to the host.
//The host can decide how to display them.
//---------------------------------------------------------------------
public void LogErrors(CompilerErrorCollection errors)
{
errorsValue = errors;
}
//This is the application domain that is used to compile and run
//the generated transformation class to create the generated text output.
//----------------------------------------------------------------------
public AppDomain ProvideTemplatingAppDomain(string content)
{
//This host will provide a new application domain each time the
//engine processes a text template.
//-------------------------------------------------------------
return AppDomain.CreateDomain("Generation App Domain");
//This could be changed to return the current appdomain, but new
//assemblies are loaded into this AppDomain on a regular basis.
//If the AppDomain lasts too long, it will grow indefintely,
//which might be regarded as a leak.
//This could be customized to cache the application domain for
//a certain number of text template generations (for example, 10).
//This could be customized based on the contents of the text
//template, which are provided as a parameter for that purpose.
}
}
}
(4)最后呢。。。运行它！不过，如果你要想脱离vs。最好加上它的运行的dll.vs2008中叫Microsoft.VisualStudio.TextTemplating.dll。至于2010呢，两个文件，自己 gg一下吧。
运行，如果最后的提示是空白，那么就对啦，如果不对。请对着提示找错吧。
