Imports System
Imports System.Text.RegularExpressions

Module RegularExpressions
    Sub Main()
        ' This tests whether a pattern matches a string.
        Dim match As Boolean = Regex.IsMatch("peach", "p([a-z]+)ch")
        Console.WriteLine(match)

        ' For other regex tasks, you'll need to create a Regex object.
        Dim r As New Regex("p([a-z]+)ch")

        ' Many methods are available on these objects. Here's a match test like we saw earlier.
        Console.WriteLine(r.IsMatch("peach"))

        ' This finds the match for the regex.
        Console.WriteLine(r.Match("peach punch").Value)

        ' This also finds the first match but returns the start and end indexes for the match.
        Dim m As Match = r.Match("peach punch")
        Console.WriteLine($"idx: [{m.Index}, {m.Index + m.Length}]")

        ' The Captures property includes information about both the whole-pattern matches 
        ' and the submatches within those matches.
        m = r.Match("peach punch")
        For Each capture As Capture In m.Captures
            Console.Write($"{capture.Value} ")
        Next
        Console.WriteLine()

        ' The All variants of these methods apply to all matches in the input, not just the first.
        ' For example, to find all matches for a regex:
        Dim matches As MatchCollection = r.Matches("peach punch pinch")
        For Each match In matches
            Console.Write($"{match.Value} ")
        Next
        Console.WriteLine()

        ' Providing a non-negative integer as the second argument to these methods will limit the number of matches.
        matches = r.Matches("peach punch pinch", 2)
        For Each match In matches
            Console.Write($"{match.Value} ")
        Next
        Console.WriteLine()

        ' The regex package can also be used to replace subsets of strings with other values.
        Console.WriteLine(r.Replace("a peach", "<fruit>"))

        ' The evaluator variant allows you to transform matched text with a given function.
        Dim result As String = r.Replace("a peach", Function(m) m.Value.ToUpper())
        Console.WriteLine(result)
    End Sub
End Module