gitextensions-ICSharpCode.TextEditor/Project/Src/Util/RedBlackTreeIterator.cs

// <file>
//     <copyright see="prj:///doc/copyright.txt"/>
//     <license see="prj:///doc/license.txt"/>
//     <owner name="Daniel Grunwald" email="daniel@danielgrunwald.de"/>
//     <version>$Revision$</version>
// </file>

using System;
using System.Collections;
using System.Collections.Generic;

namespace ICSharpCode.TextEditor.Util
{
    internal struct RedBlackTreeIterator<T> : IEnumerator<T>
    {
        internal RedBlackTreeNode<T> node;

        internal RedBlackTreeIterator(RedBlackTreeNode<T> node)
        {
            this.node = node;
        }

        public bool IsValid => node != null;

        public T Current
        {
            get
            {
                if (node != null)
                    return node.val;
                throw new InvalidOperationException();
            }
        }

        object IEnumerator.Current => Current;

        void IDisposable.Dispose()
        {
        }

        void IEnumerator.Reset()
        {
            throw new NotSupportedException();
        }

        public bool MoveNext()
        {
            if (node == null)
                return false;
            if (node.right != null)
            {
                node = node.right.LeftMost;
            }
            else
            {
                RedBlackTreeNode<T> oldNode;
                do
                {
                    oldNode = node;
                    node = node.parent;
                    // we are on the way up from the right part, don't output node again
                } while (node != null && node.right == oldNode);
            }

            return node != null;
        }

        public bool MoveBack()
        {
            if (node == null)
                return false;
            if (node.left != null)
            {
                node = node.left.RightMost;
            }
            else
            {
                RedBlackTreeNode<T> oldNode;
                do
                {
                    oldNode = node;
                    node = node.parent;
                    // we are on the way up from the left part, don't output node again
                } while (node != null && node.left == oldNode);
            }

            return node != null;
        }
    }
}