path_utils.cs

public static bool AreIdenticalPaths(DirectoryInfo dir1, DirectoryInfo dir2)
{
    return string.Compare(
        dir1.FullName.TrimEnd('/', '\\'),
        dir2.FullName.TrimEnd('/', '\\'),
        StringComparison.InvariantCultureIgnoreCase) == 0;
}

public static string MapPath(string virtualPath)
{
    return HostingEnvironment.IsHosted
        ? HostingEnvironment.MapPath(virtualPath)
        : CombinePaths(GetAppDomainDirectory(), virtualPath);
}

/*
 * 
var x = new List<string[]> {
new[] { "~/", "", "abc", @"\def", @"def\/", "def//\\/" },
new[] { "x", @"~\xy", @"\g/" },
new[] { "\\x", @"~\xy", @"\g" },
new[] { "//x", @"~\xy", @"\g/" },
new[] { @"\\documents\", @"~\xy", @"\\g/" },
    new[] { "~/" },
};
foreach (var y in x)
{
Console.WriteLine(CombinePaths(y));
}

// produces
\abc\def\def\def\
x\xy\g\
\x\xy\g
\\x\xy\g\
\\documents\xy\g\
\

*/
public static string CombinePaths(params string[] paths)
{
    if (paths == null || paths.Length == 0)
        return string.Empty;

    var first = paths[0].Replace("/", @"\").Trim();
    var last = paths[paths.Length - 1].Replace("/", @"\").Trim();

    var path = string.Join(@"\", paths.Select(p => p.Trim().Trim('~', '/', '\\')).ToArray());

    while (path.Contains(@"\\"))
        path = path.Replace(@"\\", @"\");

    while (first.StartsWith(@"\"))
    {
        first = first.Substring(1);
        path = @"\" + path;
    }

    if (last.EndsWith(@"\"))
        path += @"\";

    return NormalizeDirectorySeparatorChars(path);
}

public static string NormalizeDirectorySeparatorChars(string path)
{
    return Path.DirectorySeparatorChar == '/' ? path.Replace('\\', '/') : path.Replace('/', '\\');
}

public static string GetMachineName()
{
    string machineName;
    try
    {
        machineName = Environment.MachineName;
    }
    catch
    {
        try
        {
            machineName = Dns.GetHostName();
        }
        catch
        {
            throw new ApplicationException("Unable to retrieve the machine name");
        }
    }
    return machineName.ToAlphaNumeric('-', '-');
}

public static AppDomain GetAppDomain()
{
    return AppDomain.CurrentDomain;
}

public static string GetAppDomainDirectory()
{
    //return Path.GetDirectoryName(new Uri(Assembly.GetExecutingAssembly().CodeBase).LocalPath)
    return GetAppDomain().BaseDirectory;
}

public static string GetAppVirtualPath()
{
    return HostingEnvironment.IsHosted ? HostingEnvironment.ApplicationVirtualPath : "/";
}

public static string GetAppPhysicalPath()
{
    return MapPath("~/");
}

public static string GetAppBinDirectory()
{
    return HostingEnvironment.IsHosted ? HttpRuntime.BinDirectory :
        GetAppDomainDirectory();
}