using System;
using System.Xml;
using System.Text.RegularExpressions;

class Program {
    static void ReadAllNodes(XmlReader xr,Action<string> handler) {
        while (xr.Read()) {
            if (xr.NodeType == XmlNodeType.CDATA || xr.NodeType == XmlNodeType.Text) {
                foreach (var line in xr.Value.Split('\r','\n')) {
                    var s = line.Trim();
                    if (s.Length > 0) handler(s);
                }
            }
            if (xr.NodeType == XmlNodeType.Element) {
                for (int i = 0; i < xr.AttributeCount; i++) {
                    handler(xr[i]);
                }
            }
        }
    }
    static void FindPaths(XmlReader xr,Action<string> handler) {
        var re1 = new Regex(@"\$\([^)]+\)");
        var re2 = new Regex(@"\.xml$",RegexOptions.IgnoreCase);
        ReadAllNodes(xr,text => {
            if (re1.IsMatch(text) || re2.IsMatch(text)) handler(text);
        });
    }
    static string ExpandPath(string src,Func<string,string> expander) {
        var re = new Regex(@"\$\(([^)]+)\)");
        return re.Replace(src,match => expander(match.Groups[1].Value));
    }
    static string EnvExpander(string name) {
        var res=Environment.GetEnvironmentVariable(name);
        return res == null ? "$(" + name + ")" : res;
    }
    static void Main(string[] args) {            
        using (var xr = XmlReader.Create("test.xml")) {
            FindPaths(xr,path => {
                var fpath = ExpandPath(path,EnvExpander);
                Console.WriteLine(fpath);
            });
        }
    }
}

        static void TraceXml(int level, string inputUri)
        {
            level++;
            if (Path.GetExtension(inputUri) != ".xml")
            {
                Console.WriteLine(string.Join("", Enumerable.Repeat(' ', level)) + string.Format("File {0} is not XML.", inputUri));
                return;
            }
            // learn to read ../test.xml, *.xml
            if (!File.Exists(inputUri))
            {
                Console.WriteLine(string.Join("", Enumerable.Repeat(' ', level)) + string.Format("File {0} not exists yet.", inputUri));
                return;
            }
            Console.WriteLine(string.Join("", Enumerable.Repeat(' ', level)) + inputUri);
            using (var xr = XmlReader.Create(inputUri))
            {
                FindPaths(xr, path =>
                {
                    var fpath = ExpandPath(path, EnvExpander);
                    TraceXml(level, fpath);
                });
            }
        }
        static void Main(string[] args)
        {
            string inputUri = Environment.CurrentDirectory + "/Support/bcadtestapp.xml";
            int level = 0;
            TraceXml(level, inputUri);
        }

var re = new Regex(@"\.xml$",RegexOptions.IgnoreCase); // всё что кончается на .xml или .XmL ... - аналог *.xml

_>var re = new Regex(@"\.xml$",RegexOptions.IgnoreCase); // всё что кончается на .xml или .XmL ... - аналог *.xml
_>

            if (Path.GetFileNameWithoutExtension(initFile.FilePath) == "*")
            {
                // expend *.xml
                initFile.FileStatus = xmlFile.Status.WildCardExt;
                TreeNodes.Add(initFile);
                DirectoryInfo directoryInfo = new DirectoryInfo(Path.GetDirectoryName(initFile.FilePath));
                foreach (FileInfo thisFile in directoryInfo.GetFiles("*.xml"))
                {
                    xmlFile newFile = new xmlFile(initFile.ParentId, thisFile.FullName);
                    filesToProcess.Add(newFile);
                }
            }
            else if (initFile.FilePath.Contains(".."))
            {
                // expend ..\abc.xml
                string fileName = Path.GetFileName(initFile.FilePath);
                var re = new Regex(@"/+");
                string thisPath = re.Replace(initFile.FilePath, "\\").ToUpper();
                int howMany = 0;
                string path = thisPath;                
                do {
                    path = Regex.Replace(path, @"\.\.", "=");
                    howMany++;
                } while (path.Contains(".."));

                foreach ( xmlFile thisFile in TreeNodes.Where(x => x.Id == initFile.ParentId))
                {
                    thisPath = Path.GetDirectoryName(thisFile.FilePath);
                    for (int i = 0; i < howMany; i++)
                        thisPath = Path.GetDirectoryName(thisPath);
                    thisPath = Path.Combine(thisPath, fileName);
                    xmlFile newFile = new xmlFile(initFile.Id, thisPath);
                    filesToProcess.Add(newFile);
                }
            }