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VisitorAction Enumeration
Allows the visitor to control the enumeration of nodes.

Namespace: Aspose.Words
Assembly: Aspose.Words (in Aspose.Words.dll) Version: 19.9
Syntax
public enum VisitorAction
Members
  Member nameValueDescription
Continue0 The visitor requests the enumeration to continue.
SkipThisNode1 The visitor requests to skip the current node and continue enumeration.
Stop2 The visitor requests the enumeration of nodes to stop.
Examples
Shows how to use the Visitor pattern to add new operations to the Aspose.Words object model. In this case we create a simple document converter into a text format.
[C#]

// Open the document we want to convert.
    Document doc = new Document(MyDir + "Visitor.ToText.doc");

    // Create an object that inherits from the DocumentVisitor class.
    MyDocToTxtWriter myConverter = new MyDocToTxtWriter();

    // This is the well known Visitor pattern. Get the model to accept a visitor.
    // The model will iterate through itself by calling the corresponding methods
    // on the visitor object (this is called visiting).
    // 
    // Note that every node in the object model has the Accept method so the visiting
    // can be executed not only for the whole document, but for any node in the document.
    doc.Accept(myConverter);

    // Once the visiting is complete, we can retrieve the result of the operation,
    // that in this example, has accumulated in the visitor.
    Console.WriteLine(myConverter.GetText());
}

/// <summary>
/// Simple implementation of saving a document in the plain text format. Implemented as a Visitor.
/// </summary>
public class MyDocToTxtWriter : DocumentVisitor
{
    public MyDocToTxtWriter()
    {
        this.mIsSkipText = false;
        this.mBuilder = new StringBuilder();
    }

    /// <summary>
    /// Gets the plain text of the document that was accumulated by the visitor.
    /// </summary>
    public String GetText()
    {
        return this.mBuilder.ToString();
    }

    /// <summary>
    /// Called when a Run node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitRun(Run run)
    {
        this.AppendText(run.Text);

        // Let the visitor continue visiting other nodes.
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a FieldStart node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldStart(FieldStart fieldStart)
    {
        // In Microsoft Word, a field code (such as "MERGEFIELD FieldName") follows
        // after a field start character. We want to skip field codes and output field 
        // result only, therefore we use a flag to suspend the output while inside a field code.
        // 
        // Note this is a very simplistic implementation and will not work very well
        // if you have nested fields in a document. 
        this.mIsSkipText = true;

        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a FieldSeparator node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldSeparator(FieldSeparator fieldSeparator)
    {
        // Once reached a field separator node, we enable the output because we are
        // now entering the field result nodes.
        this.mIsSkipText = false;

        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a FieldEnd node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitFieldEnd(FieldEnd fieldEnd)
    {
        // Make sure we enable the output when reached a field end because some fields
        // do not have field separator and do not have field result.
        this.mIsSkipText = false;

        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when visiting of a Paragraph node is ended in the document.
    /// </summary>
    public override VisitorAction VisitParagraphEnd(Paragraph paragraph)
    {
        // When outputting to plain text we output Cr+Lf characters.
        this.AppendText(ControlChar.CrLf);

        return VisitorAction.Continue;
    }

    public override VisitorAction VisitBodyStart(Body body)
    {
        // We can detect beginning and end of all composite nodes such as Section, Body, 
        // Table, Paragraph etc and provide custom handling for them.
        this.mBuilder.Append("*** Body Started ***\r\n");

        return VisitorAction.Continue;
    }

    public override VisitorAction VisitBodyEnd(Body body)
    {
        this.mBuilder.Append("*** Body Ended ***\r\n");
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a HeaderFooter node is encountered in the document.
    /// </summary>
    public override VisitorAction VisitHeaderFooterStart(HeaderFooter headerFooter)
    {
        // Returning this value from a visitor method causes visiting of this
        // node to stop and move on to visiting the next sibling node.
        // The net effect in this example is that the text of headers and footers
        // is not included in the resulting output.
        return VisitorAction.SkipThisNode;
    }

    /// <summary>
    /// Called when an AbsolutePositionTab is encountered in the document.
    /// </summary>
    public override VisitorAction VisitAbsolutePositionTab(AbsolutePositionTab tab)
    {
        this.mBuilder.Append("\t");
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a BookmarkStart is encountered in the document.
    /// </summary>
    public override VisitorAction VisitBookmarkStart(BookmarkStart bookmarkStart)
    {
        this.mBuilder.Append("[");
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Called when a BookmarkEnd is encountered in the document.
    /// </summary>
    public override VisitorAction VisitBookmarkEnd(BookmarkEnd bookmarkEnd)
    {
        this.mBuilder.Append("]");
        return VisitorAction.Continue;
    }

    /// <summary>
    /// Adds text to the current output. Honours the enabled/disabled output flag.
    /// </summary>
    private void AppendText(String text)
    {
        if (!this.mIsSkipText)
            this.mBuilder.Append(text);
    }

    private readonly StringBuilder mBuilder;
    private bool mIsSkipText;
}
See Also