rainmeter-studio/RainmeterStudio/Utils/TreeExtensions.cs

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C#
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using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using RainmeterStudio.Model;
namespace RainmeterStudio.Utils
{
/// <summary>
/// Extension methods for trees
/// </summary>
public static class TreeExtensions
{
/// <summary>
/// Tree traversal orders
/// </summary>
public enum TreeTraversalOrder
{
BreadthFirst,
DepthFirst,
DepthFirstPreOrder = DepthFirst,
DepthFirstPostOrder
}
/// <summary>
/// Traverses a tree
/// </summary>
/// <typeparam name="T">Tree data type</typeparam>
/// <param name="root">Root node of tree</param>
/// <param name="order">Traversal order</param>
/// <returns>An enumeration of the nodes in the specified traverse order</returns>
public static IEnumerable<Tree<T>> Traverse<T>(this Tree<T> root, TreeTraversalOrder order = TreeTraversalOrder.BreadthFirst)
{
if (order == TreeTraversalOrder.BreadthFirst)
return TraverseBF(root);
else return TraverseDF(root, order);
}
private static IEnumerable<Tree<T>> TraverseDF<T>(this Tree<T> root, TreeTraversalOrder order)
{
// Preorder - return root first
if (order == TreeTraversalOrder.DepthFirstPreOrder)
yield return root;
// Return children
foreach (var child in root.Children)
foreach (var node in TraverseDF(child, order))
yield return node;
// Postorder - return root last
if (order == TreeTraversalOrder.DepthFirstPostOrder)
yield return root;
}
private static IEnumerable<Tree<T>> TraverseBF<T>(this Tree<T> root)
{
// Create a queue containing the root
Queue<Tree<T>> queue = new Queue<Tree<T>>();
queue.Enqueue(root);
// While there are elements in the queue
while (queue.Count > 0)
{
// Return next node in tree
var node = queue.Dequeue();
yield return node;
// Enqueue node's children
foreach (var child in node.Children)
queue.Enqueue(child);
}
}
/// <summary>
/// Applies an action to every node of the tree
/// </summary>
/// <typeparam name="T">Tree data type</typeparam>
/// <param name="root">Root node of tree</param>
/// <param name="action">Action to apply</param>
/// <param name="order">Traversal order</param>
public static void Apply<T>(this Tree<T> root, Action<Tree<T>> action, TreeTraversalOrder order = TreeTraversalOrder.BreadthFirst)
{
// Safety check
if (action == null)
return;
// Apply action
foreach (var node in Traverse(root, order))
action(node);
}
/// <summary>
/// Applies an action to every node of the tree
/// </summary>
/// <typeparam name="T">Tree data type</typeparam>
/// <param name="root">Root node of tree</param>
/// <param name="action">Action to apply</param>
/// <param name="order">Traversal order</param>
public static void ApplyToData<T>(this Tree<T> root, Action<T> action, TreeTraversalOrder order = TreeTraversalOrder.BreadthFirst)
where T : class
{
// Safety check
if (action == null)
return;
// Apply action
foreach (var node in Traverse(root, order))
action(node.Data);
}
/// <summary>
/// Rebuilds the tree by applying the specified transform function
/// </summary>
/// <typeparam name="T">Data type of tree</typeparam>
/// <typeparam name="TResult">Data type of rebuilt tree</typeparam>
/// <param name="root">The root node</param>
/// <param name="transformFunction">The transform function</param>
/// <returns>The transformed tree</returns>
public static Tree<TResult> Transform<T,TResult>(this Tree<T> root, Func<Tree<T>, Tree<TResult>> transformFunction)
{
// Safety check
if (transformFunction == null)
throw new ArgumentNullException("Transform function cannot be null.");
// Build root
Tree<TResult> resRoot = transformFunction(root);
// Add children
foreach (var node in root.Children)
resRoot.Children.Add(Transform(node, transformFunction));
// Return
return resRoot;
}
/// <summary>
/// Rebuilds the tree by applying the specified transform function
/// </summary>
/// <typeparam name="T">Data type of tree</typeparam>
/// <typeparam name="TResult">Data type of rebuilt tree</typeparam>
/// <param name="root">The root node</param>
/// <param name="transformFunction">The transform function</param>
/// <returns>The transformed tree</returns>
public static Tree<TResult> TransformData<T, TResult>(this Tree<T> root, Func<T, TResult> transformFunction)
{
// Safety check
if (transformFunction == null)
throw new ArgumentNullException("Transform function cannot be null.");
// Build root
Tree<TResult> resRoot = new Tree<TResult>(transformFunction(root.Data));
// Add children
foreach (var node in root.Children)
resRoot.Children.Add(TransformData(node, transformFunction));
// Return
return resRoot;
}
}
}