FormulaEngine.Parse(String) Method

Parses the specified formula using the default context.

Namespace: DevExpress.Spreadsheet.Formulas

Assembly: DevExpress.Spreadsheet.v23.2.Core.dll

NuGet Package: DevExpress.Spreadsheet.Core

Declaration

C#

ParsedExpression Parse(
    string formula
)

VB.NET

Function Parse(
    formula As String
) As ParsedExpression

Parameters

Name	Type	Description
formula	String	A string that is the expression to parse. The leading equals “=” symbol is optional.

Returns

Type	Description
ParsedExpression	A ParsedExpression object providing access to the expression tree.

Remarks

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.

View Example

MyVisitor.vb

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

Form1.vb

Imports DevExpress.Spreadsheet
Imports DevExpress.Spreadsheet.Formulas
Imports DevExpress.Spreadsheet.Functions
            Dim engine As FormulaEngine = spreadsheetControl1.Document.FormulaEngine
            If spreadsheetControl1.ActiveCell IsNot Nothing Then
                ' Get the formula for parsing. 
                Dim formula As String = spreadsheetControl1.ActiveCell.Formula
                If formula <> String.Empty Then
                    ' Parse the formula
                    Dim p_expr As ParsedExpression = engine.Parse(formula)
                    ' Traverse the expression tree and modify it.
                    Dim visitor As New MyVisitor()
                    p_expr.Expression.Visit(visitor)
                    ' Reconsitute the formula.
                    Dim formula1 As String = p_expr.ToString()
                    ' Place the formula back to the cell.
                    spreadsheetControl1.ActiveCell.Formula = formula1
                End If

Form1.cs

using DevExpress.Spreadsheet;
using DevExpress.Spreadsheet.Formulas;
using DevExpress.Spreadsheet.Functions;
            FormulaEngine engine = spreadsheetControl1.Document.FormulaEngine;
            if (spreadsheetControl1.ActiveCell != null){
                // Get the formula for parsing. 
                string formula = spreadsheetControl1.ActiveCell.Formula;
                if (formula != string.Empty)
                {
                    // Parse the formula
                    ParsedExpression p_expr = engine.Parse(formula);
                    // Traverse the expression tree and modify it.
                    MyVisitor visitor = new MyVisitor();
                    p_expr.Expression.Visit(visitor);
                    // Reconsitute the formula.
                    string formula1 = p_expr.ToString();
                    // Place the formula back to the cell.
                    spreadsheetControl1.ActiveCell.Formula = formula1;
                }

MyVisitor.cs

public class MyVisitor : DevExpress.Spreadsheet.Formulas.ExpressionVisitor
{
    public override void Visit(DevExpress.Spreadsheet.Formulas.CellReferenceExpression expression)
    {
        base.Visit(expression);

        expression.CellArea.TopRowIndex++;
        expression.CellArea.BottomRowIndex++;
    }
}

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the Parse(String) method.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

winforms-spreadsheet-use-formula-engine/CS/FormulaEngineTest/Form1.cs#L87

// Parse the formula
ParsedExpression p_expr = engine.Parse(formula);
// Traverse the expression tree and modify it.

VB.NET

winforms-spreadsheet-use-formula-engine/VB/FormulaEngineTest/Form1.vb#L80

' Parse the formula
Dim p_expr As ParsedExpression = engine.Parse(formula)
' Traverse the expression tree and modify it.