How to add an 'if' statement

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VB

hey guys,

i am making my programming language and i have the ability to write and set variables. one more thing that i would like to add is 'if' statements. my programming language script is now this:

Imports System
Imports System.Text.RegularExpressions

Public Class Form1

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        TextBox2.Text = TextBox2.Text & String.Empty
        For Each a As String In TextBox1.Text.Split(ControlChars.Lf)
            If a.StartsWith("vw ") Then
                TextBox2.Text &= IIf(String.IsNullOrEmpty(TextBox2.Text), _
                    String.Empty, vbCrLf) & System.Text.RegularExpressions.Regex.Match( _
                    TextBox1.Text, String.Format("(?<=vs {0},).*", a.Substring(3)), _
                    RegexOptions.CultureInvariant).Value
            End If
        Next
    End Sub
End Class

and the grammar is:

function operation1,operation2,operation3
| vs name,value
| vw name
| if value,expression,statement endif

vs = variable set
vw = variable write
if = if statement

in other words, the if statement if like if value = expression do statement. but i cut out the '=' sign and the 'do' word and replaced them with commas. can someone please give me an updated version of my code that has that if statement?