Class Library to Automatically Maintain Persistent Variables, Properties and Data Between Sessions

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

// Part of RJConfig V1.3

// Classes for the File Variable

namespace RJConfig
{
	/// <remarks>
	/// The FileVariable class holds the Name and String value for a variable that can be 
	/// saved to and restored from a file.
	/// </remarks>
	public class FileVariable
	{
		/// <summary>
		/// The value string.
		/// </summary>
		protected string mData;
		/// <summary>
		/// The variable name.
		/// </summary>
		protected string mName;
		/// <summary>
		/// Public constructor.
		/// </summary>
		/// <param name="Name">Name of the variable.</param>
		/// <param name="Data">String representing the variable value.</param>
		public FileVariable (string Name, string Data)
		{
			mData = Data;
			mName = Name;
		}
		/// <summary>
		/// Public access property for the value string.
		/// </summary>
		public string Data
		{
			get
			{
				return mData;
			}
			set
			{
				mData = value;
			}
		}
		/// <summary>
		/// Public read only property for the Variable name.
		/// </summary>
		public string Name
		{
			get
			{
				return mName;
			}
		}
		/// <summary>
		/// Function to convert the string value to and from an int.
		/// </summary>
		public int IntValue
		{
			get
			{
				try {
					return Int32.Parse(mData);
				} catch {
					return 0;	// Returns the value 0 if the string can't be parsed as an int.
				}
			}
			set
			{
				mData = string.Format("{0}", value);
			}
		}
		/// <summary>
		/// Function to convert the string value to and from a bool.
		/// </summary>
		public bool BoolValue
		{
			get
			{
				return ((string.Compare(mData, "1") == 0) || (string.Compare(mData, "TRUE", true) == 0) || (string.Compare(mData, "ON") == 0));
				// false is returned for anything but true as above.
			}
			set
			{
				mData = string.Format("{0}", value ? "true" : "false");
			}
		}
	}
	/// <remarks>
	/// An extended LinkedList with FileVariables.
	/// FileVariables uses linked lists instead of dictionaries as ConfigVariables since there can
	/// be more than one FileVariable with the same name.
	/// </remarks>
	public class FileVariableList : LinkedList<FileVariable>
	{
		/// <summary>
		/// Find the first FileVariable with a specified name.
		/// </summary>
		/// <param name="VariableName">Name of the variable.</param>
		/// <returns>A FileVariable object for the first FileVariable found with the specified name.
		/// Null if no variable with that name exists.</returns>
		public FileVariable FindVariable (string VariableName)
		{
			if (string.IsNullOrEmpty(VariableName))
				return null;
			foreach (FileVariable fv in this) {
				if (fv.Name == VariableName)
					return fv;
			}
			return null;
		}
		/// <summary>
		/// Used to iterate through the linked list of FileVariables. Call FirstVariable to get
		/// the first FileVariable in the linked list.
		/// </summary>
		/// <param name="Node">A reference parameter for the node in the linked list. This must be used 
		/// for all subsequent calls to NextVariable</param>
		/// <returns>The first FileVariable in the linked list. Null if the list is empty.</returns>
		public FileVariable FirstVariable (ref LinkedListNode<FileVariable> Node)
		{
			Node = First;
			if (Node != null)
				return Node.Value;
			return null;
		}
		/// <summary>
		/// Used to iterate through the linked list of FileVariables. Must be preceded with a call
		/// to FirstVariable.
		/// </summary>
		/// <param name="Node">A reference parameter for the node in the linked list. This must be used
		/// for all subsequent calls to NextVariable</param>
		/// <returns>The next FileVariable in the linked list. Null if there are no more variables in
		/// the list.</returns>
		public FileVariable NextVariable (ref LinkedListNode<FileVariable> Node)
		{
			Node = Node.Next;
			if (Node != null) {
				return Node.Value;
			}
			return null;
		}
		/// <summary>
		/// Removes a FileVariable node from the linked list.
		/// </summary>
		/// <param name="fv">The FileVariable to be removed.</param>
		public void RemoveVariable (FileVariable fv)
		{
			Remove(fv);
		}
		/// <summary>
		/// Creates a FileVariable and adds it last to the linked list.
		/// Note that there can be more than one variable with the same name in the list.
		/// </summary>
		/// <param name="Variable">The name of the variable.</param>
		/// <param name="Data">The value, as a string, for the variable.</param>
		/// <returns>The newly created FileVariable object.</returns>
		public FileVariable AddVariable (string Variable, string Data)
		{
			FileVariable fv = new FileVariable(Variable, Data);
			AddLast(fv);
			return fv;
		}
		/// <summary>
		/// Find a named variable in the linked list and create it if it doesn't exist.
		/// This can only be used if there only should be variables with unique names in the list.
		/// </summary>
		/// <param name="Variable">Name of the variable.</param>
		/// <param name="Default">The default string value for the variable if it doesn't already exist.</param>
		/// <returns>The newly created or first found variable with the specified name.</returns>
		/// <exception cref="Exception">
		/// Thrown if the variable name is null or empty.
		/// </exception>
		public FileVariable FindVariableCreate (string Variable, string Default)
		{
			if (string.IsNullOrEmpty(Variable)) {
				throw new Exception("Variable name can not be null or empty!");
			}
			FileVariable fv = FindVariable(Variable);
			if (fv == null) {
				fv = new FileVariable(Variable, Default);
				AddLast(fv);
			}
			return fv;
		}
		/// <summary>
		/// Convert the linked list of FileVariables to XML nodes and add them to the 
		/// XML document, ready to be saved to file.
		/// </summary>
		/// <param name="xd">The XML document for the file the variables exists in.</param>
		/// <param name="xn">The XML node where the created child node should be added.</param>
		public void ToXmlDoc (XmlDocument xd, XmlNode xn)
		{
			XmlElement xeVar, xeData;
			foreach (FileVariable fv in this) {
				xeVar = xd.CreateElement("Variable");
				xeVar.SetAttribute("Name", fv.Name);
				xeData = xd.CreateElement("Value");
				try {
					xeData.InnerXml = fv.Data;	// If it can't be saved as an XML element 
				} catch {
					xeData.InnerText = fv.Data;
				}
				xeVar.AppendChild(xeData);
				xn.AppendChild(xeVar);
			}
		}
	}
}