Imports System.Text.RegularExpressions

Public Class UsingRegEx

    Const Blank As Char = ChrW(32)

    Const pt1 As String = "--.*[^\r\n]"                 ' -- (Singleline Comment)

    Const pt2 As String = "/\*((?:.|\s)*?)\*/"          ' /**/ (Multiline Comment)

    Const pt3 As String = "[N]?'((?:.|\s)*?)'"          ' Single Quotes

    Const pt4 As String = "\u0022((?:.|\s)*?)\u0022"    ' Double Quotes

    Const pt5 As String = "\[((?:.|\s)*?)\]"            ' []

    Const Pattern_Ignore = pt1 + "|" + pt2 + "|" + pt3 + "|" + pt4 + "|" + pt5





    Private Sub Btn_Process_Click(sender As Object, e As EventArgs) Handles Btn_Process.Click

        LB_Words.Items.Clear()

        LB_Keywords.Items.Clear()

        Dim strSQL As String = TB_Source.Text

        Dim strMOD As String = strSQL

        For Each m As Match In Regex.Matches(strMOD, Pattern_Ignore, RegexOptions.Multiline)

            strMOD = strMOD.Remove(m.Index, m.Length)

            strMOD = strMOD.Insert(m.Index, FillWhiteSpaces(m.Value))

        Next

        TB_Modified.Text = strMOD

        'strMOD = Regex.Replace(strSQL, pattern, String.Empty)

        Dim x As List(Of Char) = "(),;!=<>+-*/%^|&~".ToList

        For Each c In x

            strMOD = strMOD.Replace(c, Blank + c + Blank)

        Next

        strMOD = Regex.Replace(strMOD, "\s", Blank)

        strMOD = Regex.Replace(strMOD, "[  ]{2,}", Blank)

        Dim Words As List(Of String) = strMOD.Trim.Split(Blank).ToList

        For Each word In Words

            If Regex.IsMatch(word, "^[a-zA-Z_@]+$") Then

                LB_Words.Items.Add(word)

                If SQL_KeyWords.Contains(word.ToUpper) Then

                    LB_Keywords.Items.Add(word)

                End If

            End If

        Next

    End Sub



    Function FillWhiteSpaces(str As String) As String

        Return Regex.Replace(NZ(str), "\s", ChrW(&HFFFD))

    End Function



    Private Function NZ(str As String) As String

        If String.IsNullOrEmpty(str) Then

            Return String.Empty

        Else

            Return str

        End If

    End Function

End Class