Imports System
Imports System.Collections.Generic

Public Class QueryString

    Private _items As Dictionary(Of QueryStringKey, String)
    Private _pageUrl As String
    Private _requestQs As NameValueCollection
    '----------------------------------------------------------------------------------------------
    Public Sub New(ByVal pageUrl As String, Optional ByVal requestQs As NameValueCollection = _
    Nothing)
        _pageUrl = pageUrl
        _items = New Dictionary(Of QueryStringKey, String)
        _requestQs = requestQs
    End Sub
    '----------------------------------------------------------------------------------------------
    Private Sub New(ByVal pageUrl As String, ByVal items As Dictionary(Of QueryStringKey, _
    String), ByVal requestQs As NameValueCollection)
        _pageUrl = pageUrl
        _items = items
        _requestQs = requestQs
    End Sub
    '----------------------------------------------------------------------------------------------
    Public Function Add(ByVal key As QueryStringKey, ByVal value As String) As QueryString
        _items.Add(key, value)
        Return Me
    End Function
    '----------------------------------------------------------------------------------------------
    Public Function Remove(ByVal key As QueryStringKey) As QueryString
        _items.Remove(key)
        Return Me
    End Function
    '----------------------------------------------------------------------------------------------
    Public Function FullUrl(Optional ByVal requestQs As NameValueCollection = Nothing) As String
        Return FullUrl(_pageUrl, requestQs)
    End Function
    '----------------------------------------------------------------------------------------------
    Public Function FullUrl(ByVal pageUrl As String, Optional ByVal requestQs As _
    NameValueCollection = Nothing) As String

        If requestQs IsNot Nothing Then
            _requestQs = requestQs
        End If

        Dim result As String = pageUrl
        Dim delim As String = "?"
        Dim qsl As QueryStringLookup = New QueryStringLookup()

        For Each s As QueryStringKey In _items.Keys
            result &= delim
            result &= qsl.GetKey(s)
            result &= "="
            result &= HttpContext.Current.Server.UrlEncode(_items(s))
            delim = "&"
        Next

        If _requestQs IsNot Nothing Then

            For Each s As String In _requestQs.Keys

                result &= delim
                result &= s
                result &= "="
                result &= _requestQs(s)
                delim = "&"

            Next

        End If

        Return result

    End Function
    '----------------------------------------------------------------------------------------------
    Public Function Clone() As QueryString

        Dim items As Dictionary(Of QueryStringKey, String) = _
                    New Dictionary(Of QueryStringKey, String)

        For Each key As QueryStringKey In _items.Keys
            items.Add(key, _items(key))
        Next

        Dim requestQs As NameValueCollection = New NameValueCollection()

        For Each s As String In _requestQs
            requestQs.Add(s, _requestQs(s))
        Next

        Return New QueryString(_pageUrl, items, requestQs)

    End Function

End Class

using System;
using System.Collections.Generic;

public class QueryString
{
    
    private Dictionary<QueryStringKey, string> _items;
    private string _pageUrl;
    private NameValueCollection _requestQs;

    //---------------------------------------------------------------------------------------------
    public QueryString(string pageUrl)
    {
        _pageUrl = pageUrl;
        _items = new Dictionary<QueryStringKey, string>();
        _requestQs = null;
    }
    //---------------------------------------------------------------------------------------------
    public QueryString(string pageUrl, NameValueCollection requestQs)
    {
        _pageUrl = pageUrl;
        _items = new Dictionary<QueryStringKey, string>();
        _requestQs = requestQs
    }
    //---------------------------------------------------------------------------------------------
    private QueryString(string pageUrl, Dictionary<QueryStringKey, string> items, 
    NameValueCollection requestQs)
    {
        _pageUrl = pageUrl;
        _items = items;
        _requestQs = requestQs;
    }
    //---------------------------------------------------------------------------------------------
    public QueryString Add(QueryStringKey key, string value)
    {
        _items.Add(key, value);
        return this;
    }
    //---------------------------------------------------------------------------------------------
    public QueryString Remove(QueryStringKey key)
    {
        _items.Remove(key);
        return this;
    }
    //---------------------------------------------------------------------------------------------
    public string FullUrl()
    {
        return FullUrl(_pageUrl);
    }
    //---------------------------------------------------------------------------------------------
    public string FullUrl(string pageUrl)
    {
        return FullUrl(pageUrl, null);
    }
    //---------------------------------------------------------------------------------------------
    public string FullUrl(string pageUrl, NameValueCollection requestQs)
    {
        if (requestQs != null)
            _requestQs = requestQs

        string result = pageUrl;
        string delim = "?";
        QueryStringLookup qsl = new QueryStringLookup();

        foreach (QueryStringKey s in _items.Keys)
        {
            result += delim;
            result += qs.GetKey(s);
            result += "=";
            result += HttpContext.Current.Server.UrlEncode(_items[s]);
            delim = "&";
        }

        if (_requestQs != null)
        {
            foreach (string s in _requestQs.Keys)
            {
                result += delim;
                result += s;
                result += "=";
                result += _requestQs[s];
                delim = "&";
            }
        }

        return result;
    }
    //---------------------------------------------------------------------------------------------
    public QueryString Clone()
    {
        try
        {
            Dictionary<QueryStringKey, string> items = new Dictionary<QueryStringKey, string>();
            foreach (QueryStringKey key in _items.Keys)
                try
                {
                    items.Add(key, _items[key]);
                }
                catch (Exception ex)
                {
                    throw ex;
                }

            NameValueCollection requestQs = new NameValueCollection();
            foreach (string s in requestQs)
                requestQs.Add(s, requestQs[s]);

            return new QueryString(_pageUrl, items, requestQs);
        }
        catch (Exception ex)
        {
            throw ex;
        }
    }
}