rspec/rules/S5856/vbnet/rule.adoc

== Why is this an issue?

include::../description.adoc[]

Negative lookahead and negative lookbehind groups cannot be combined with `RegexOptions.NonBacktracking`. Such combination would throw an exception during runtime.

=== Noncompliant code example

[source,vbnet]
----
Public Sub DoSomething(Input As String)
    Dim Rx As New Regex("[A")                   ' Noncompliant
    Dim Match = Regex.Match(Input, "[A")        ' Noncompliant
    Dim Matches = Regex.Matches(Input, "[A")    ' Noncompliant
    Dim Replace = Regex.Replace(Input, "[A", "replacement")     ' Noncompliant
    Dim Split = Regex.Split(Input, "[A")        ' Noncompliant
    If (Regex.IsMatch(Input, "[A")) Then        ' Noncompliant
    End If
    Dim NegativeLookahead As New Regex("a(?!b)", RegexOptions.NonBacktracking)      ' Noncompliant
    Dim NegativeLookbehind As New Regex("(?<!a)b", RegexOptions.NonBacktracking)    ' Noncompliant
End Sub
----

=== Compliant solution

[source,vbnet]
----
Public Sub DoSomething(Input As String)
    Dim Rx As New Regex("[A-Z]")
    Dim Match = Regex.Match(Input, "[A-Z]")
    Dim Matches = Regex.Matches(Input, "[A-Z]")
    Dim Replace = Regex.Replace(Input, "[A-Z]", "replacement")
    Dim Split = Regex.Split(Input, "[A-Z]")
    If (Regex.IsMatch(Input, "[A-Z]")) Then
    End If
    Dim NegativeLookahead As New Regex("a(?!b)")
    Dim NegativeLookbehind As New Regex("(?<!a)b")
End Sub
----

include::../rspecator.adoc[]