/// <summary>
/// Tries to get a node's parent.
/// </summary>
/// <typeparam name="T">The type of elements in the tree.</typeparam>
/// <param name="walker">
/// The <see cref="ITreeWalker<T>"/> that knows how to find the parent and child
/// nodes.
/// </param>
/// <param name="node">
/// The node whose parent is to be returned.
/// </param>
/// <param name="parent">
/// A reference to the resulting parent node. This will be a default value of type
/// <typeparamref name="T"/> if we fail to get a the parent node.
/// </param>
/// <returns>
/// True if a parent node is found, false, otherwise.
/// </returns>
public static bool TryGetParent <T>(this ITreeWalker <T> walker, T node, out T parent)
{
// Validate parameters.
if (walker == null)
{
throw new ArgumentNullException("walker");
}
if (node == null)
{
throw new ArgumentNullException("node");
}
// Get the ancestors enumerator and attempt to move to the first node.
// If we get the first node output it and return true. Otherwise, output a default
// node and return false.
using (IEnumerator <T> enumerator = walker.GetAncestors(node).GetEnumerator())
{
if (enumerator.MoveNext())
{
parent = enumerator.Current;
return(true);
}
else
{
parent = default(T);
return(false);
}
}
}
/// <summary>
/// Determines if a node has a parent.
/// </summary>
/// <typeparam name="T">The type of elements in the tree.</typeparam>
/// <param name="walker">
/// The <see cref="ITreeWalker<T>"/> that knows how to find the parent and child nodes.
/// </param>
/// <param name="node">
/// The node being checked for a parent.
/// </param>
/// <returns>
/// Returns a <see cref="System.Boolean"/> indicating whether or not the node has a parent.
/// </returns>
public static bool HasParent <T>(this ITreeWalker <T> walker, T node)
{
// Validate parameters.
if (walker == null)
{
throw new ArgumentNullException("walker");
}
if (node == null)
{
throw new ArgumentNullException("node");
}
return(walker.GetAncestors(node).Any());
}
/// <summary>
/// Returns a node's parent or a default node if no parent exists.
/// </summary>
/// <typeparam name="T">The type of elements in the tree.</typeparam>
/// <param name="walker">
/// The <see cref="ITreeWalker<T>"/> that knows how to find the parent and child nodes.
/// </param>
/// <param name="node">
/// The node whose parent is to be returned.
/// </param>
/// <returns>
/// Returns a node's parent or a default node if no parent exists.
/// </returns>
public static T GetParentOrDefault <T>(this ITreeWalker <T> walker, T node)
{
// Validate parameters.
if (walker == null)
{
throw new ArgumentNullException("walker");
}
if (node == null)
{
throw new ArgumentNullException("node");
}
// Return the node's parent or a default node if the parent does not exist.
return(walker.GetAncestors(node).FirstOrDefault());
}
/// <summary>
/// Gets the depth of the node. The depth is measured by the number of edges between
/// <paramref name="node"/> and the root of the tree.
/// </summary>
/// <typeparam name="T">The type of elements in the tree.</typeparam>
/// <param name="walker">
/// The <see cref="ITreeWalker<T>"/> that knows how to find the parent and child nodes.
/// </param>
/// <param name="node">
/// The node whose depth is to be returned.
/// </param>
/// <returns>
/// The number of edges between <paramref name="node"/> and the root of the tree.
/// </returns>
public static int GetDepth <T>(this ITreeWalker <T> walker, T node)
{
// Validate parameters.
if (walker == null)
{
throw new ArgumentNullException("walker");
}
if (node == null)
{
throw new ArgumentNullException("node");
}
// Return the depth of 'node' by counting the nodes ancestors.
return(walker.GetAncestors(node).Count());
}
/// <summary>
/// Gets a node and the node's ancestors, starting with its parent node and ending with
/// the root node.
/// </summary>
/// <typeparam name="T">The type of elements in the tree.</typeparam>
/// <param name="walker">
/// The <see cref="ITreeWalker<T>"/> that knows how to find the parent and child
/// nodes.
/// </param>
/// <param name="node">
/// The node whose ancestors are to be returned.
/// </param>
/// <returns>
/// An <see cref="System.Collections.Generic.IEnumerable<T>"/> that contains the node
/// and all of the node's ancestors, up to and including the root.
/// </returns>
public static IEnumerable <T> GetAncestorsAndSelf <T>(this ITreeWalker <T> walker, T node)
{
if (walker == null)
{
throw new ArgumentNullException("walker");
}
if (node == null)
{
throw new ArgumentNullException("node");
}
yield return(node);
foreach (T item in walker.GetAncestors(node))
{
yield return(item);
}
}
