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DirectiveProcessor (Clase)

Clase base abstracta de un procesador de directivas concreto.

Jerarquía de herencia

System.Object
  Microsoft.VisualStudio.TextTemplating.DirectiveProcessor
    Microsoft.VisualStudio.TextTemplating.ParameterDirectiveProcessor
    Microsoft.VisualStudio.TextTemplating.RequiresProvidesDirectiveProcessor

Espacio de nombres:  Microsoft.VisualStudio.TextTemplating
Ensamblado:  Microsoft.VisualStudio.TextTemplating.11.0 (en Microsoft.VisualStudio.TextTemplating.11.0.dll)

Sintaxis

'Declaración
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

El tipo DirectiveProcessor expone los siguientes miembros.

Constructores

  Nombre Descripción
Método protegido DirectiveProcessor Cuando se reemplaza en una clase derivada, inicializa una nueva instancia de la clase DirectiveProcessor.

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Propiedades

  Nombre Descripción
Propiedad protegida Errors Obtiene los errores que se produjeron al procesar las directivas.

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Métodos

  Nombre Descripción
Método público Equals Determina si el objeto especificado es igual al objeto actual. (Se hereda de Object).
Método protegido Finalize Permite que un objeto intente liberar recursos y realizar otras operaciones de limpieza antes de ser reclamado por la recolección de elementos no utilizados. (Se hereda de Object).
Método público FinishProcessingRun Cuando se reemplaza en una clase derivada, finaliza una fase de procesamiento de directivas.
Método público GetClassCodeForProcessingRun Cuando se reemplaza en una clase derivada, obtiene el código que se va a agregar a la clase de transformación generada.
Método público GetHashCode Actúa como función hash para un tipo concreto. (Se hereda de Object).
Método público GetImportsForProcessingRun Cuando se reemplaza en una clase derivada, obtiene los espacios de nombres que se van a importar en la clase de transformación generada.
Método público GetPostInitializationCodeForProcessingRun Cuando se reemplaza en una clase derivada, obtiene el código que se va a agregar al final del método de inicialización de la clase de transformación generada.
Método público GetPreInitializationCodeForProcessingRun Cuando se reemplaza en una clase derivada, obtiene código para agregar el inicio del método initialize de la clase de transformación generada.
Método público GetReferencesForProcessingRun Cuando se reemplaza en una clase derivada, obtiene las referencias que se van a pasar al compilador de la clase de transformación generada.
Método público GetTemplateClassCustomAttributes Obtenga cualquier atributo personalizado para colocar la clase de plantilla.
Método público GetType Obtiene el objeto Type de la instancia actual. (Se hereda de Object).
Método público Initialize Cuando se reemplaza en una clase derivada, inicializa la instancia del procesador.
Método público IsDirectiveSupported Cuando se reemplaza en una clase derivada, determina si el procesador de directivas admite la directiva especificada.
Método protegido MemberwiseClone Crea una copia superficial del objeto Object actual. (Se hereda de Object).
Método público ProcessDirective Cuando se reemplaza en una clase derivada, procesa una sola directiva de un archivo de plantilla.
Método público StartProcessingRun Cuando se reemplaza en una clase derivada, comienza una fase de procesamiento de directivas.
Método público ToString Devuelve una cadena que representa el objeto actual. (Se hereda de Object).

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Implementaciones explícitas de interfaces

  Nombre Descripción
Implementación explícita de interfacesPropiedad privada IDirectiveProcessor.Errors
Implementación explícita de interfacesPropiedad privada IDirectiveProcessor.RequiresProcessingRunIsHostSpecific
Implementación explícita de interfacesMétodo privado IDirectiveProcessor.SetProcessingRunIsHostSpecific

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Comentarios

El proceso de transformación de plantilla de texto consta de dos pasos.En el primer paso, el motor de transformación de plantillas de texto crea una clase que se denomina la clase de transformación generada.En el segundo paso, el motor compila y ejecuta la clase de transformación generada, para producir la salida de texto generada.

Los procesadores de directivas funcionan agregando código a la clase de transformación generada.Se puede llamar a las directivas desde una plantilla de texto y, después de llamar a una directiva, el resto del código que escribe en su plantilla de texto puede basarse en la funcionalidad proporcionada por la directiva.Puede escribir sus propios procesadores de directivas personalizados para proporcionar funcionalidad personalizada a las plantillas de texto.

Para obtener más información, vea Crear procesadores de directivas personalizadas para las plantillas de texto T4.

El motor de transformación de plantilla de texto contendrá una instancia singleton de cualquier clase DirectiveProcessor necesaria.

DirectiveProcessor implementa una máquina de estados.

Por ejemplo, si una plantilla de texto tiene tres llamadas de directiva al mismo procesador de directivas, el motor llamará a los siguientes métodos en el siguiente orden:

Ejemplos

En el ejemplo siguiente se crea un procesador de directivas personalizado.El procesador de directivas personalizado contiene una directiva que lee un archivo XML.La directiva almacena el XML en una variable XmlDocument y expone XmlDocument a través de una propiedad.

Para obtener más información, vea Tutorial: Crear un procesador de directivas personalizadas.

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

Seguridad para subprocesos

Todos los miembros static (Shared en Visual Basic) públicos de este tipo son seguros para la ejecución de subprocesos. No se garantiza que los miembros de instancias sean seguros para la ejecución de subprocesos.

Vea también

Referencia

Microsoft.VisualStudio.TextTemplating (Espacio de nombres)

RequiresProvidesDirectiveProcessor

Otros recursos

Crear procesadores de directivas personalizadas para las plantillas de texto T4

Tutorial: Crear un procesador de directivas personalizadas