A base class for implementing a custom visitor to traverse the expression tree.
This example demonstrates how to use the FormulaEngine.Parse method to parse an expression and create an expression tree. The expression tree is available by using the ParsedExpression.Expression property.
You can use an expression tree visitor to traverse an existing expression tree and to perform required actions when it visits a specific node. To implement a visitor, create a descendant from the ExpressionVisitor class and override the ExpressionVisitor.Visit method which corresponds to the node type you wish to visit.
In this code snippet, the MyVisitor visitor changes the range reference to shift it down by one row.
After the visitor finishes, the ParsedExpression.ToString method is used to assemble a valid formula from the expression tree.
A complete sample project is available at https://github.com/DevExpress-Examples/formula-engine-examples-of-use-t110344
Public Class MyVisitor Inherits DevExpress.Spreadsheet.Formulas.ExpressionVisitor Public Overrides Sub Visit(ByVal expression As DevExpress.Spreadsheet.Formulas.CellReferenceExpression) MyBase.Visit(expression) expression.CellArea.TopRowIndex += 1 expression.CellArea.BottomRowIndex += 1 End Sub End Class