Bidirecional dictionary WITH CASE-INSENSITIVENESS?

Question

Question: I use the bidirectional dicionary class I found here: Bidirectional 1 to 1 Dictionary in C#

The problem is, I need this - case insensitive (StringComparer.OrdinalIgnoreCase)

I wanna extend it to cover the IEqualityComparer constructor. I've converted it to VB (works like a charm), but I have trouble implementing the comparer 'transfer'.

The problem is, in the parameters I have:

ByVal x As System.Collections.Generic.IEqualityComparer(Of TKey)

But the dicionary secondToFirst is of type TValue, TKey, which kills my IEqualityComparer, which needs to be of type TValue instead of TKey...

How do I typecast this comparer ?

If somewhere there's another class for BiDictionaryOneToOne, with case-insensitiveness, that's also OK (as long as that library isn't monumental in size/memory consumption and .NET 2.0)

Public Class BiDictionaryOneToOne(Of TKey, TValue)


    Public Sub New(ByVal x As System.Collections.Generic.IEqualityComparer(Of TKey))
        Dim y As System.Collections.Generic.IEqualityComparer(Of TValue) = StringComparer.OrdinalIgnoreCase

        firstToSecond = New Dictionary(Of TKey, TValue)(x)
        secondToFirst = New Dictionary(Of TValue, TKey)(y)
    End Sub

Edit:
OK, of course it's only possible if TKey & TValue are of type string, as John points out, but in case they are the same, it's still possible with try/catch like this:

Public Sub New(ByVal cmpFirstDirection As System.Collections.Generic.IEqualityComparer(Of TKey))

    Try
        Dim cmpOppositeDirection As System.Collections.Generic.IEqualityComparer(Of TValue) = CType(cmpFirstDirection, System.Collections.Generic.IEqualityComparer(Of TValue))
        firstToSecond = New Dictionary(Of TKey, TValue)(cmpFirstDirection)
        secondToFirst = New Dictionary(Of TValue, TKey)(cmpOppositeDirection)
    Catch ex As Exception
        firstToSecond = New Dictionary(Of TKey, TValue)(cmpFirstDirection)
        secondToFirst = New Dictionary(Of TValue, TKey)
    End Try

End Sub



Public Sub New(ByVal cmpFirstDirection As System.Collections.Generic.IEqualityComparer(Of TKey), ByVal cmpOppositeDirection As System.Collections.Generic.IEqualityComparer(Of TValue))
    firstToSecond = New Dictionary(Of TKey, TValue)(cmpFirstDirection)
    secondToFirst = New Dictionary(Of TValue, TKey)(cmpOppositeDirection)
End Sub

score 1 · Accepted Answer · answered Feb 25 '11 at 10:30

You're trying to write a generic bi-dictionary which could have any key/value pair combination of types. What does it mean to compare two integers using StringComparer? I suggest you change your constructor to take two IEqualityComparers, one for TKey and one for TValue. You can then create a BiDictionaryOneToOne(Of String, String) which is case-insensitive by passing in two appropriate IEqualityComparer(Of String) values.

Bidirecional dictionary WITH CASE-INSENSITIVENESS?

1 Answers1