graph.cs

This is a document about routing [a spatial analysis - network]

using System;

namespace MapService
{
	/// <summary>
	/// The Graph class represents a graph, which is composed of a collection of nodes and edges.  This Graph class
	/// maintains its collection of nodes using the NodeList class, which is a collection of Node objects.
	/// It delegates the edge maintenance to the Node class.  The Node class maintains the edge information using
	/// the adjacency list technique.
	/// </summary>
	public class Graph
	{
		#region Private Member Variables
		// private member variables
		private NodeList nodes;
		#endregion

		#region Constructor
		/// <summary>
		/// Default constructor.  Creates a new Graph class instance.
		/// </summary>
		public Graph()
		{
			this.nodes = new NodeList();
		}

		/// <summary>
		/// Creates a new graph class instance based on a list of nodes.
		/// </summary>
		/// <param name="nodes">The list of nodes to populate the newly created Graph class with.</param>
		public Graph(NodeList nodes)
		{
			this.nodes = nodes;
		}
		#endregion

		public virtual void Clear()
		{
			nodes.Clear();
		}

		#region Adding Node Methods
		/// <summary>
		/// Adds a new node to the graph.
		/// </summary>
		/// <param name="key">The key value of the node to add.</param>
		/// <param name="data">The data of the node to add.</param>
		/// <returns>A reference to the Node that was created and added to the graph.</returns>
		/// <remarks>If there already exists a node in the graph with the same <b>key</b> value then an
		/// <b>ArgumentException</b> exception will be thrown.</remarks>
		public virtual Node AddNode(string key, object data)
		{
			// Make sure the key is unique
			if (!nodes.ContainsKey(key))
			{
				Node n = new Node(key, data);
				nodes.Add(n);
				return n;
			}
			else
				throw new ArgumentException("There already exists a node in the graph with key " + key);
		}

		/// <summary>
		/// Adds a new node to the graph.
		/// </summary>
		/// <param name="n">A node instance to add to the graph</param>
		/// <remarks>If there already exists a node in the graph with the same <b>key</b> value as <b>n</b> then an
		/// <b>ArgumentException</b> exception will be thrown.</remarks>
		public virtual void AddNode(Node n)
		{
			// Make sure this node is unique
			if (!nodes.ContainsKey(n.Key))
				nodes.Add(n);
			else
				throw new ArgumentException("There already exists a node in the graph with key " + n.Key);
		}

        public void Remove(Node n)
        {
            if(nodes.ContainsKey(n.Key))
            {
                nodes.Remove(n);
            }
        }
		#endregion

		public virtual void AddEdge(Node u, Node v, bool twoway)
		{
            if (nodes.ContainsKey(u.Key) && nodes.ContainsKey(v.Key))
            {
                if(twoway)
                {
                    u.AddEdge(v, true);//u->v
                    v.AddEdge(u, true);//v->u
                }
                else
                    u.AddEdge(v, false);//u-v
            }
		}

		public virtual bool Contains(Node n)
		{
			return Contains(n.Key);
		}

		public virtual bool Contains(string key)
		{
			return nodes.ContainsKey(key);
		}

		#region Public Properties
		/// <summary>
		/// Returns the number of nodes in the graph.
		/// </summary>
		public virtual int Count
		{
			get
			{
				return nodes.Count;
			}
		}

		/// <summary>
		/// Returns a reference to the set of nodes in the graph.
		/// </summary>
		public virtual NodeList Nodes
		{
			get
			{
				return this.nodes;
			}
		}
		#endregion
	}
}