/project/core/Config/preprocessor/XHelpers.cs

using System;

using System.Collections.Generic;

using System.Linq;

using System.Xml;

using System.Xml.Linq;



namespace ThoughtWorks.CruiseControl.Core.Config.Preprocessor

{

    /// <summary>

    /// Extension methods for System.Xml.Linq

    /// </summary>

    public static class XHelpers

    {

        /// <summary>

        /// Does the element have an attribute of the given name?

        /// </summary>

        /// <param name="element">element to check</param>

        /// <param name="attrName">attribute to check for</param>

        /// <returns>true/false</returns>

        public static bool HasAttribute(this XElement element, XName attrName)

        {

            return element.Attribute(attrName) != null;

        }



        /// <summary>

        /// Returns the first sibling that follows the given element.

        ///  </summary>

        /// <param name="element">Element whose sibling is returned</param>

        /// <returns>First following sibling element, or null if no siblings exist</returns>

        public static XElement NextSiblingElement(this XElement element)

        {

            return element.ElementsAfterSelf().FirstOrDefault();

        }



        /// <summary>

        /// Extracts file and line/position information from the given object, in displayable form,

        /// for use in error messages.

        /// </summary>

        /// <param name="obj">Xml object for whom to return the context</param>

        /// <returns>A string of the form "File: [file_path] line XXX, pos YYY"</returns>

        public static string ErrorContext(this XObject obj)

        {

            string obj_info = "";

            var xattribute = obj as XAttribute;



            if (xattribute != null)

            {

                obj_info = string.Format(System.Globalization.CultureInfo.CurrentCulture,"Attribute '{0}'", xattribute.Name);

            }

            else

            {

                var xelement = obj as XElement;

                if (xelement != null)

                {

                    obj_info = string.Format(System.Globalization.CultureInfo.CurrentCulture,"Element '{0}'", xelement.Name);

                }

            }

            IXmlLineInfo line_info = obj;

            string line_and_pos = "line and position unknown";

            if (line_info.HasLineInfo())

            {

                line_and_pos = string.Format(System.Globalization.CultureInfo.CurrentCulture,"line {0}, pos {1}", line_info.LineNumber,

                                              line_info.LinePosition);

            }

            return string.Format(System.Globalization.CultureInfo.CurrentCulture,"File: {0} ({1}:{2})", obj.BaseUri, line_and_pos, obj_info);

        }



        /// <summary>

        /// Returns the given element's named attribute value as a string 

        /// </summary>

        /// <param name="element">Element whose value is returned</param>

        /// <param name="attrName">Name of attribute to return</param>

        /// <returns>Attribute value, or empty string if no such attribute exists</returns>

        public static string GetAttributeValue(this XElement element, XName attrName)

        {

            XAttribute attr = element.Attribute(attrName);

            return attr == null ? "" : attr.Value;

        }



        /// <summary>

        /// Returns the concatenated text values of the given nodeset

        /// </summary>

        /// <param name="nodes">Nodeset whose values are returned</param>

        /// <returns>Untrimmed, concatenated text values of the given nodeset</returns>

        public static string GetTextValue(this IEnumerable<XNode> nodes)

        {

            return String.Concat(nodes.Select<XNode, String>(_ValueOf).ToArray());

        }



        private static string _ValueOf(XNode node)

        {

            switch (node.NodeType)

            {

                case XmlNodeType.Element:

                    return ((XElement)node).Value;

                case XmlNodeType.Text:

                    return ((XText)node).Value;

                case XmlNodeType.Comment:

                case XmlNodeType.ProcessingInstruction:

                    return String.Empty;

                default:

                    throw new InvalidOperationException(

                        string.Format(System.Globalization.CultureInfo.CurrentCulture,"{0} Unhandled node type {1}",

                                       node.ErrorContext(),

                                       node.NodeType));

            }

        }

    }



    /// <summary>

    /// 	

    /// </summary>

    public static class XmlNs

    {

        /// <summary>

        /// 	

        /// </summary>

        /// <remarks></remarks>

        public static XNamespace PreProcessor = XNamespace.Get("urn:ccnet.config.builder");

    }

}