55 строки
1.8 KiB
C#
55 строки
1.8 KiB
C#
// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
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// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
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using System;
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using System.Collections.Generic;
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namespace ICSharpCode.TreeView
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{
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/// <summary>
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/// Static helper methods for traversing trees.
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/// </summary>
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static class TreeTraversal
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{
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/// <summary>
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/// Converts a tree data structure into a flat list by traversing it in pre-order.
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/// </summary>
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/// <param name="root">The root element of the tree.</param>
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/// <param name="recursion">The function that gets the children of an element.</param>
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/// <returns>Iterator that enumerates the tree structure in pre-order.</returns>
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public static IEnumerable<T> PreOrder<T>(T root, Func<T, IEnumerable<T>> recursion)
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{
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return PreOrder(new T[] { root }, recursion);
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}
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/// <summary>
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/// Converts a tree data structure into a flat list by traversing it in pre-order.
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/// </summary>
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/// <param name="input">The root elements of the forest.</param>
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/// <param name="recursion">The function that gets the children of an element.</param>
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/// <returns>Iterator that enumerates the tree structure in pre-order.</returns>
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public static IEnumerable<T> PreOrder<T>(IEnumerable<T> input, Func<T, IEnumerable<T>> recursion)
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{
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Stack<IEnumerator<T>> stack = new Stack<IEnumerator<T>>();
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try {
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stack.Push(input.GetEnumerator());
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while (stack.Count > 0) {
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while (stack.Peek().MoveNext()) {
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T element = stack.Peek().Current;
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yield return element;
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IEnumerable<T> children = recursion(element);
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if (children != null) {
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stack.Push(children.GetEnumerator());
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}
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}
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stack.Pop().Dispose();
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}
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} finally {
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while (stack.Count > 0) {
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stack.Pop().Dispose();
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}
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}
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}
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}
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}
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