XmlDocumentLoader.cs

using System.Collections.Generic;
using System.IO;
using System.Xml;

namespace BmwDeepObd
{
    public class XmlDocumentLoader
    {
        // Public Static Methods

        #region LoadWithIncludes(string filename)

        public static XmlDocument LoadWithIncludes(string filename)
        {
            XmlDocument xml = new XmlDocument();

            xml.Load(filename);
            ProcessIncludeNodes(xml, xml.DocumentElement, Path.GetDirectoryName(filename));

            return xml;
        }

        #endregion

        // Private Static Methods
        #region ProcessIncludeNodes(XmlDocument xml, XmlNode parent, string basePath)
        
        public static void ProcessIncludeNodes(XmlDocument xml, XmlNode parent, string basePath)
        {
            List<XmlNode> removeList = new List<XmlNode>();

            foreach (XmlNode node in parent.ChildNodes)
            {
                if (node.Name.ToLower() == "include" && node.Attributes != null)
                {
                    string filename = node.Attributes["filename"].Value;
                    if (!Path.IsPathRooted(filename))
                    {
                        filename = Path.Combine(basePath, filename);
                    }

                    XmlDocument include = LoadWithIncludes(filename);
                    if (include?.DocumentElement != null)
                    {
                        foreach (XmlNode inner in include.DocumentElement.ChildNodes)
                        {
                            XmlNode imported = xml.ImportNode(inner, true);
                            if (imported.Attributes != null)
                            {
                                XmlAttribute fileNameAttr = xml.CreateAttribute("include_filename");
                                fileNameAttr.Value = filename;
                                imported.Attributes.Append(fileNameAttr);
                            }
                            parent.InsertBefore(imported, node);
                        }
                    }

                    removeList.Add(node);
                }
                else
                {
                    ProcessIncludeNodes(xml, node, basePath);
                }
            }

            foreach (XmlNode node in removeList)
            {
                parent.RemoveChild(node);
            }
        }
        #endregion
    }
}