DirectiveProcessor 类
具体指令处理器的抽象基类。
继承层次结构
System.Object
Microsoft.VisualStudio.TextTemplating.DirectiveProcessor
Microsoft.VisualStudio.TextTemplating.ParameterDirectiveProcessor
Microsoft.VisualStudio.TextTemplating.RequiresProvidesDirectiveProcessor
命名空间： Microsoft.VisualStudio.TextTemplating
程序集： Microsoft.VisualStudio.TextTemplating.11.0（在 Microsoft.VisualStudio.TextTemplating.11.0.dll 中）
语法
声明
Public MustInherit Class DirectiveProcessor _
Implements IDirectiveProcessor
public abstract class DirectiveProcessor : IDirectiveProcessor
public ref class DirectiveProcessor abstract : IDirectiveProcessor
[<AbstractClass>]
type DirectiveProcessor =
class
interface IDirectiveProcessor
end
public abstract class DirectiveProcessor implements IDirectiveProcessor
DirectiveProcessor 类型公开以下成员。
构造函数
| 名称 | 说明 | |
|---|---|---|
.gif "受保护的方法") |
DirectiveProcessor | 在派生类中重写时，初始化 DirectiveProcessor 类的新实例。 |
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属性
| 名称 | 说明 | |
|---|---|---|
.gif "受保护的属性") |
Errors | 让生成，在处理指令时的错误。 |
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方法
| 名称 | 说明 | |
|---|---|---|
.gif "公共方法") |
Equals | 确定指定的对象是否等于当前对象。 （继承自 Object。） |
|
Finalize | 允许对象在“垃圾回收”回收之前尝试释放资源并执行其他清理操作。 （继承自 Object。） |
|
FinishProcessingRun | 在派生类中重写时，完成一轮指令处理。 |
|
GetClassCodeForProcessingRun | 在派生类中重写时，获取要添加到已生成转换类的代码。 |
|
GetHashCode | 用作特定类型的哈希函数。 （继承自 Object。） |
|
GetImportsForProcessingRun | 在派生类中重写时，获取要导入到已生成转换类的命名空间。 |
|
GetPostInitializationCodeForProcessingRun | 在派生类中重写时，获取要添加到已生成转换类的 initialize 方法末尾的代码。 |
|
GetPreInitializationCodeForProcessingRun | 当重写在派生类中，获取代码添加到生成转换选件类的初始化方法的开头。 |
|
GetReferencesForProcessingRun | 在派生类中重写时，获取要传递到已生成转换类编译器的引用。 |
|
GetTemplateClassCustomAttributes | 获取将模板选件类的任何自定义属性。 |
|
GetType | 获取当前实例的 Type。 （继承自 Object。） |
|
Initialize | 在派生类中重写时，初始化处理器实例。 |
|
IsDirectiveSupported | 当重写在派生类中，确定指令处理器是否支持指定的指令。 |
|
MemberwiseClone | 创建当前 Object 的浅表副本。 （继承自 Object。） |
|
ProcessDirective | 在派生类中重写时，根据模板文件处理单个指令。 |
|
StartProcessingRun | 当重写在派生类中，开始舍入指令处理。 |
|
ToString | 返回表示当前对象的字符串。 （继承自 Object。） |
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显式接口实现
| 名称 | 说明 | |
|---|---|---|
.gif "显式接口实现") .gif "私有属性") |
IDirectiveProcessor.Errors | |
|
IDirectiveProcessor.RequiresProcessingRunIsHostSpecific | |
.gif "私有方法") |
IDirectiveProcessor.SetProcessingRunIsHostSpecific |
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备注
文本模板转换过程有两个步骤。 在第一步中，文本模板转换引擎将创建一个称为生成的转换类的类。 在第二步中，该引擎编译和执行生成的转换类，以产生生成的文本输出。
指令处理器通过向生成转换类添加代码发挥作用。 从文本模板调用指令，在调用一个指令后，文本模板中编写的其余代码可能依赖该指令提供的功能。 您可以编写自己的自定义指令处理器来提供文本模板的自定义功能。
有关更多信息，请参见 创建自定义 T4 文本模板指令处理器。
文本模板转换引擎将保留任何所需的 DirectiveProcessor 类的单一实例。
DirectiveProcessor 实现状态机。
例如，如果文本模板具有同一指令处理器的三个指令调用，则引擎将会按以下顺序调用以下方法：
StartProcessingRun
示例
下面的示例创建一个自定义指令处理器。 自定义指令处理器包含读取 XML 文件的一个指令。 该指令在 XmlDocument 变量中存储 XML，通过属性公开 XmlDocument。
有关更多信息，请参见演练：创建自定义指令处理器。
using System;
using System.CodeDom;
using System.CodeDom.Compiler;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Serialization;
using Microsoft.VisualStudio.TextTemplating;
namespace CustomDP
{
public class CustomDirectiveProcessor : DirectiveProcessor
{
//this buffer stores the code that is added to the
//generated transformation class after all the processing is done
//---------------------------------------------------------------------
private StringBuilder codeBuffer;
//Using a Code Dom Provider creates code for the
//generated transformation class in either Visual Basic or C#.
//If you want your directive processor to support only one language, you
//can hard code the code you add to the generated transformation class.
//In that case, you do not need this field.
//--------------------------------------------------------------------------
private CodeDomProvider codeDomProvider;
//this stores the full contents of the text template that is being processed
//--------------------------------------------------------------------------
private String templateContents;
//These are the errors that occur during processing. The engine passes
//the errors to the host, and the host can decide how to display them,
//for example the the host can display the errors in the UI
//or write them to a file.
//---------------------------------------------------------------------
private CompilerErrorCollection errorsValue;
public new CompilerErrorCollection Errors
{
get { return errorsValue; }
}
//Each time this directive processor is called, it creates a new property.
//We count how many times we are called, and append "n" to each new
//property name. The property names are therefore unique.
//-----------------------------------------------------------------------------
private int directiveCount = 0;
public override void Initialize(ITextTemplatingEngineHost host)
{
//we do not need to do any initialization work
}
public override void StartProcessingRun(CodeDomProvider languageProvider, String templateContents, CompilerErrorCollection errors)
{
//the engine has passed us the language of the text template
//we will use that language to generate code later
//----------------------------------------------------------
this.codeDomProvider = languageProvider;
this.templateContents = templateContents;
this.errorsValue = errors;
this.codeBuffer = new StringBuilder();
}
//Before calling the ProcessDirective method for a directive, the
//engine calls this function to see whether the directive is supported.
//Notice that one directive processor might support many directives.
//---------------------------------------------------------------------
public override bool IsDirectiveSupported(string directiveName)
{
if (string.Compare(directiveName, "CoolDirective", StringComparison.OrdinalIgnoreCase) == 0)
{
return true;
}
if (string.Compare(directiveName, "SuperCoolDirective", StringComparison.OrdinalIgnoreCase) == 0)
{
return true;
}
return false;
}
public override void ProcessDirective(string directiveName, IDictionary<string, string> arguments)
{
if (string.Compare(directiveName, "CoolDirective", StringComparison.OrdinalIgnoreCase) == 0)
{
string fileName;
if (!arguments.TryGetValue("FileName", out fileName))
{
throw new DirectiveProcessorException("Required argument 'FileName' not specified.");
}
if (string.IsNullOrEmpty(fileName))
{
throw new DirectiveProcessorException("Argument 'FileName' is null or empty.");
}
//Now we add code to the generated transformation class.
//This directive supports either Visual Basic or C#, so we must use the
//System.CodeDom to create the code.
//If a directive supports only one language, you can hard code the code.
//--------------------------------------------------------------------------
CodeMemberField documentField = new CodeMemberField();
documentField.Name = "document" + directiveCount + "Value";
documentField.Type = new CodeTypeReference(typeof(XmlDocument));
documentField.Attributes = MemberAttributes.Private;
CodeMemberProperty documentProperty = new CodeMemberProperty();
documentProperty.Name = "Document" + directiveCount;
documentProperty.Type = new CodeTypeReference(typeof(XmlDocument));
documentProperty.Attributes = MemberAttributes.Public;
documentProperty.HasSet = false;
documentProperty.HasGet = true;
CodeExpression fieldName = new CodeFieldReferenceExpression(new CodeThisReferenceExpression(), documentField.Name);
CodeExpression booleanTest = new CodeBinaryOperatorExpression(fieldName, CodeBinaryOperatorType.IdentityEquality, new CodePrimitiveExpression(null));
CodeExpression rightSide = new CodeMethodInvokeExpression(new CodeTypeReferenceExpression("XmlReaderHelper"), "ReadXml", new CodePrimitiveExpression(fileName));
CodeStatement[] thenSteps = new CodeStatement[] { new CodeAssignStatement(fieldName, rightSide) };
CodeConditionStatement ifThen = new CodeConditionStatement(booleanTest, thenSteps);
documentProperty.GetStatements.Add(ifThen);
CodeStatement s = new CodeMethodReturnStatement(fieldName);
documentProperty.GetStatements.Add(s);
CodeGeneratorOptions options = new CodeGeneratorOptions();
options.BlankLinesBetweenMembers = true;
options.IndentString = " ";
options.VerbatimOrder = true;
options.BracingStyle = "C";
using (StringWriter writer = new StringWriter(codeBuffer, CultureInfo.InvariantCulture))
{
codeDomProvider.GenerateCodeFromMember(documentField, writer, options);
codeDomProvider.GenerateCodeFromMember(documentProperty, writer, options);
}
}//end CoolDirective
//One directive processor can contain many directives.
//If you want to support more directives, the code goes here...
//-----------------------------------------------------------------
if (string.Compare(directiveName, "supercooldirective", StringComparison.OrdinalIgnoreCase) == 0)
{
//code for SuperCoolDirective goes here...
}//end SuperCoolDirective
//Track how many times the processor has been called.
//-----------------------------------------------------------------
directiveCount++;
}//end ProcessDirective
public override void FinishProcessingRun()
{
this.codeDomProvider = null;
//important: do not do this:
//the get methods below are called after this method
//and the get methods can access this field
//-----------------------------------------------------------------
//this.codeBuffer = null;
}
public override string GetPreInitializationCodeForProcessingRun()
{
//Use this method to add code to the start of the
//Initialize() method of the generated transformation class.
//We do not need any pre-initialization, so we will just return "".
//-----------------------------------------------------------------
//GetPreInitializationCodeForProcessingRun runs before the
//Initialize() method of the base class.
//-----------------------------------------------------------------
return String.Empty;
}
public override string GetPostInitializationCodeForProcessingRun()
{
//Use this method to add code to the end of the
//Initialize() method of the generated transformation class.
//We do not need any post-initialization, so we will just return "".
//------------------------------------------------------------------
//GetPostInitializationCodeForProcessingRun runs after the
//Initialize() method of the base class.
//-----------------------------------------------------------------
return String.Empty;
}
public override string GetClassCodeForProcessingRun()
{
//Return the code to add to the generated transformation class.
//-----------------------------------------------------------------
return codeBuffer.ToString();
}
public override string[] GetReferencesForProcessingRun()
{
//This returns the references that we want to use when
//compiling the generated transformation class.
//-----------------------------------------------------------------
//We need a reference to this assembly to be able to call
//XmlReaderHelper.ReadXml from the generated transformation class.
//-----------------------------------------------------------------
return new string[]
{
"System.Xml",
this.GetType().Assembly.Location
};
}
public override string[] GetImportsForProcessingRun()
{
//This returns the imports or using statements that we want to
//add to the generated transformation class.
//-----------------------------------------------------------------
//We need CustomDP to be able to call XmlReaderHelper.ReadXml
//from the generated transformation class.
//-----------------------------------------------------------------
return new string[]
{
"System.Xml",
"CustomDP"
};
}
}//end class CustomDirectiveProcessor
//-------------------------------------------------------------------------
// the code that we are adding to the generated transformation class
// will call this method
//-------------------------------------------------------------------------
public static class XmlReaderHelper
{
public static XmlDocument ReadXml(string fileName)
{
XmlDocument d = new XmlDocument();
using (XmlTextReader reader = new XmlTextReader(fileName))
{
try
{
d.Load(reader);
}
catch (System.Xml.XmlException e)
{
throw new DirectiveProcessorException("Unable to read the XML file.", e);
}
}
return d;
}
}//end class XmlReaderHelper
}//end namespace CustomDP
Imports System
Imports System.CodeDom
Imports System.CodeDom.Compiler
Imports System.Collections.Generic
Imports System.Globalization
Imports System.IO
Imports System.Text
Imports System.Xml
Imports System.Xml.Serialization
Imports Microsoft.VisualStudio.TextTemplating
Namespace CustomDP
Public Class CustomDirectiveProcessor
Inherits DirectiveProcessor
'this buffer stores the code that is added to the
'generated transformation class after all the processing is done
'---------------------------------------------------------------
Private codeBuffer As StringBuilder
'Using a Code Dom Provider creates code for the
'generated transformation class in either Visual Basic or C#.
'If you want your directive processor to support only one language, you
'can hard code the code you add to the generated transformation class.
'In that case, you do not need this field.
'--------------------------------------------------------------------------
Private codeDomProvider As CodeDomProvider
'this stores the full contents of the text template that is being processed
'--------------------------------------------------------------------------
Private templateContents As String
'These are the errors that occur during processing. The engine passes
'the errors to the host, and the host can decide how to display them,
'for example the the host can display the errors in the UI
'or write them to a file.
'---------------------------------------------------------------------
Private errorsValue As CompilerErrorCollection
Public Shadows ReadOnly Property Errors() As CompilerErrorCollection
Get
Return errorsValue
End Get
End Property
'Each time this directive processor is called, it creates a new property.
'We count how many times we are called, and append "n" to each new
'property name. The property names are therefore unique.
'--------------------------------------------------------------------------
Private directiveCount As Integer = 0
Public Overrides Sub Initialize(ByVal host As ITextTemplatingEngineHost)
'we do not need to do any initialization work
End Sub
Public Overrides Sub StartProcessingRun(ByVal languageProvider As CodeDomProvider, ByVal templateContents As String, ByVal errors As CompilerErrorCollection)
'the engine has passed us the language of the text template
'we will use that language to generate code later
'----------------------------------------------------------
Me.codeDomProvider = languageProvider
Me.templateContents = templateContents
Me.errorsValue = errors
Me.codeBuffer = New StringBuilder()
End Sub
'Before calling the ProcessDirective method for a directive, the
'engine calls this function to see whether the directive is supported.
'Notice that one directive processor might support many directives.
'---------------------------------------------------------------------
Public Overrides Function IsDirectiveSupported(ByVal directiveName As String) As Boolean
If String.Compare(directiveName, "CoolDirective", StringComparison.OrdinalIgnoreCase) = 0 Then
Return True
End If
If String.Compare(directiveName, "SuperCoolDirective", StringComparison.OrdinalIgnoreCase) = 0 Then
Return True
End If
Return False
End Function
Public Overrides Sub ProcessDirective(ByVal directiveName As String, ByVal arguments As IDictionary(Of String, String))
If String.Compare(directiveName, "CoolDirective", StringComparison.OrdinalIgnoreCase) = 0 Then
Dim fileName As String
If Not (arguments.TryGetValue("FileName", fileName)) Then
Throw New DirectiveProcessorException("Required argument 'FileName' not specified.")
End If
If String.IsNullOrEmpty(fileName) Then
Throw New DirectiveProcessorException("Argument 'FileName' is null or empty.")
End If
'Now we add code to the generated transformation class.
'This directive supports either Visual Basic or C#, so we must use the
'System.CodeDom to create the code.
'If a directive supports only one language, you can hard code the code.
'--------------------------------------------------------------------------
Dim documentField As CodeMemberField = New CodeMemberField()
documentField.Name = "document" & directiveCount & "Value"
documentField.Type = New CodeTypeReference(GetType(XmlDocument))
documentField.Attributes = MemberAttributes.Private
Dim documentProperty As CodeMemberProperty = New CodeMemberProperty()
documentProperty.Name = "Document" & directiveCount
documentProperty.Type = New CodeTypeReference(GetType(XmlDocument))
documentProperty.Attributes = MemberAttributes.Public
documentProperty.HasSet = False
documentProperty.HasGet = True
Dim fieldName As CodeExpression = New CodeFieldReferenceExpression(New CodeThisReferenceExpression(), documentField.Name)
Dim booleanTest As CodeExpression = New CodeBinaryOperatorExpression(fieldName, CodeBinaryOperatorType.IdentityEquality, New CodePrimitiveExpression(Nothing))
Dim rightSide As CodeExpression = New CodeMethodInvokeExpression(New CodeTypeReferenceExpression("XmlReaderHelper"), "ReadXml", New CodePrimitiveExpression(fileName))
Dim thenSteps As CodeStatement() = New CodeStatement() {New CodeAssignStatement(fieldName, rightSide)}
Dim ifThen As CodeConditionStatement = New CodeConditionStatement(booleanTest, thenSteps)
documentProperty.GetStatements.Add(ifThen)
Dim s As CodeStatement = New CodeMethodReturnStatement(fieldName)
documentProperty.GetStatements.Add(s)
Dim options As CodeGeneratorOptions = New CodeGeneratorOptions()
options.BlankLinesBetweenMembers = True
options.IndentString = " "
options.VerbatimOrder = True
options.BracingStyle = "VB"
Using writer As StringWriter = New StringWriter(codeBuffer, CultureInfo.InvariantCulture)
codeDomProvider.GenerateCodeFromMember(documentField, writer, options)
codeDomProvider.GenerateCodeFromMember(documentProperty, writer, options)
End Using
End If 'CoolDirective
'One directive processor can contain many directives.
'If you want to support more directives, the code goes here...
'-----------------------------------------------------------------
If String.Compare(directiveName, "supercooldirective", StringComparison.OrdinalIgnoreCase) = 0 Then
'code for SuperCoolDirective goes here
End If 'SuperCoolDirective
'Track how many times the processor has been called.
'-----------------------------------------------------------------
directiveCount += 1
End Sub 'ProcessDirective
Public Overrides Sub FinishProcessingRun()
Me.codeDomProvider = Nothing
'important: do not do this:
'the get methods below are called after this method
'and the get methods can access this field
'-----------------------------------------------------------------
'Me.codeBuffer = Nothing
End Sub
Public Overrides Function GetPreInitializationCodeForProcessingRun() As String
'Use this method to add code to the start of the
'Initialize() method of the generated transformation class.
'We do not need any pre-initialization, so we will just return "".
'-----------------------------------------------------------------
'GetPreInitializationCodeForProcessingRun runs before the
'Initialize() method of the base class.
'-----------------------------------------------------------------
Return String.Empty
End Function
Public Overrides Function GetPostInitializationCodeForProcessingRun() As String
'Use this method to add code to the end of the
'Initialize() method of the generated transformation class.
'We do not need any post-initialization, so we will just return "".
'------------------------------------------------------------------
'GetPostInitializationCodeForProcessingRun runs after the
'Initialize() method of the base class.
'-----------------------------------------------------------------
Return String.Empty
End Function
Public Overrides Function GetClassCodeForProcessingRun() As String
'Return the code to add to the generated transformation class.
'-----------------------------------------------------------------
Return codeBuffer.ToString()
End Function
Public Overrides Function GetReferencesForProcessingRun() As String()
'This returns the references that we want to use when
'compiling the generated transformation class.
'-----------------------------------------------------------------
'We need a reference to this assembly to be able to call
'XmlReaderHelper.ReadXml from the generated transformation class.
'-----------------------------------------------------------------
Return New String() {"System.Xml", Me.GetType().Assembly.Location}
End Function
Public Overrides Function GetImportsForProcessingRun() As String()
'This returns the imports or using statements that we want to
'add to the generated transformation class.
'-----------------------------------------------------------------
'We need CustomDP to be able to call XmlReaderHelper.ReadXml
'from the generated transformation class.
'-----------------------------------------------------------------
Return New String() {"System.Xml", "CustomDP"}
End Function
End Class 'CustomDirectiveProcessor
'--------------------------------------------------------------------------
' the code that we are adding to the generated transformation class
' will call this method
'--------------------------------------------------------------------------
Public Class XmlReaderHelper
Public Shared Function ReadXml(ByVal fileName As String) As XmlDocument
Dim d As XmlDocument = New XmlDocument()
Using reader As XmlTextReader = New XmlTextReader(fileName)
Try
d.Load(reader)
Catch e As System.Xml.XmlException
Throw New DirectiveProcessorException("Unable to read the XML file.", e)
End Try
End Using
Return d
End Function
End Class 'XmlReaderHelper
End Namespace
线程安全
此类型的任何公共 static（在 Visual Basic 中为 Shared） 成员都是线程安全的。但不保证所有实例成员都是线程安全的。
请参见
参考
Microsoft.VisualStudio.TextTemplating 命名空间
RequiresProvidesDirectiveProcessor