Subtree.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / WIN_WINDOWS / lh_tools_devdiv_wpf / Windows / wcp / Core / System / Windows / Media / Animation / Subtree.cs / 1 / Subtree.cs
                        
                        
                            //------------------------------------------------------------------------------ 
//  Microsoft Windows Client Platform
//  Copyright (c) Microsoft Corporation, 2003
//
//  File:       Subtree.cs 
//-----------------------------------------------------------------------------
 
using System; 
using System.Diagnostics;
using System.Collections; 
using System.Collections.Generic;

using MS.Internal.PresentationCore;
 
namespace System.Windows.Media.Animation
{ 
    [FriendAccessAllowed] // Built into Core, also used by Framework. 
    [System.Flags]
    internal enum SubtreeFlag 
    {
        Reset                       = 1,
        ProcessRoot                 = 2,
        SkipSubtree                 = 4, 
    }
 
    ///  
    /// An object that enumerates the clocks of a subtree of Clock
    /// objects. 
    /// 
    internal struct PrefixSubtreeEnumerator
    {
        #region Constructor 

        ///  
        /// Creates an enumerator that iterates over a subtree of clocks 
        /// in prefix order.
        ///  
        /// 
        /// The clock that is the root of the subtree to enumerate.
        /// 
        ///  
        /// True to include the root in the enumeration, false otherwise.
        ///  
        internal PrefixSubtreeEnumerator(Clock root, bool processRoot) 
        {
            _rootClock = root; 
            _currentClock = null;
            _flags = processRoot ? (SubtreeFlag.Reset | SubtreeFlag.ProcessRoot) : SubtreeFlag.Reset;
        }
 
        #endregion // Constructor
 
        #region Methods 

        ///  
        /// Causes the enumerator to not enumerate the clocks in the subtree rooted
        /// at the current clock.
        /// 
        internal void SkipSubtree() 
        {
            _flags |= SubtreeFlag.SkipSubtree; 
        } 

        ///  
        /// Advances the enumerator to the next element of the collection.
        /// 
        /// 
        /// true if the enumerator was successfully advanced to the next element, 
        /// false if the enumerator has passed the end of the collection.
        ///  
        public bool MoveNext() 
        {
            // Get the iteration started in the right place, if we are just starting 
            if ((_flags & SubtreeFlag.Reset) != 0)
            {
                // We are just getting started. The first clock is either the root
                // or its first child 
                if ((_flags & SubtreeFlag.ProcessRoot) != 0)
                { 
                    // Start with the root 
                    _currentClock = _rootClock;
                } 
                else
                {
                    // Start with the root's first child
                    if (_rootClock != null) 
                    {
                        ClockGroup rootClockGroup = _rootClock as ClockGroup; 
                        if (rootClockGroup != null) 
                        {
                            _currentClock = rootClockGroup.FirstChild; 
                        }
                        else
                        {
                            _currentClock = null; 
                        }
                    } 
                } 

                // Next time we won't be getting started anymore 
                _flags &= ~SubtreeFlag.Reset;
            }
            else if (_currentClock != null)
            { 
                // The next clock is possibly the first child of the current clock
                ClockGroup currentClockGroup = _currentClock as ClockGroup; 
 
                Clock nextClock = (currentClockGroup == null) ? null : currentClockGroup.FirstChild;
 
                // Skip the children if explicitly asked to do so, or if there aren't any
                if (((_flags & SubtreeFlag.SkipSubtree) != 0) || (nextClock == null))
                {
                    // Pop back to the first ancestor that has siblings (current clock included). Don't 
                    // go back further than the root of the subtree. At the end of this loop, nextClock
                    // will point to the proper next clock. 
                    while ((_currentClock != _rootClock) && ((nextClock = _currentClock.NextSibling) == null)) 
                    {
                        _currentClock = _currentClock.InternalParent; 
                    }

                    // Don't process siblings of the root
                    if (_currentClock == _rootClock) 
                    {
                        nextClock = null; 
                    } 

                    _flags &= ~SubtreeFlag.SkipSubtree; 
                }

                _currentClock = nextClock;
            } 

            return _currentClock != null; 
        } 

        ///  
        /// Sets the enumerator to its initial position, which is before the
        /// first element in the collection.
        /// 
        public void Reset() 
        {
            _currentClock = null; 
            _flags = (_flags & SubtreeFlag.ProcessRoot) | SubtreeFlag.Reset; 
        }
 
        #endregion // Methods

        #region Properties
 
        /// 
        /// Gets the current element in the collection. 
        ///  
        internal Clock Current
        { 
            get
            {
                return _currentClock;
            } 
        }
 
        #endregion // Properties 

        #region Data 

        private Clock       _rootClock;
        private Clock       _currentClock;
        private SubtreeFlag         _flags; 

        #endregion // Data 
    } 

    ///  
    /// An object that enumerates the clocks of a subtree of Clock
    /// objects.
    /// 
    internal struct PostfixSubtreeEnumerator 
    {
        #region Constructor 
 
        internal PostfixSubtreeEnumerator(Clock root, bool processRoot)
        { 
            _rootClock = root;
            _currentClock = null;
            _flags = processRoot ? (SubtreeFlag.Reset | SubtreeFlag.ProcessRoot) : SubtreeFlag.Reset;
        } 

        #endregion // Constructor 
 
        #region Methods
 
        /// 
        /// Advances the enumerator to the next element of the collection.
        /// 
        ///  
        /// true if the enumerator was successfully advanced to the next element,
        /// false if the enumerator has passed the end of the collection. 
        ///  
        public bool MoveNext()
        { 
            // Get started in the right place
            if ((_flags & SubtreeFlag.Reset) != 0)
            {
                _currentClock = _rootClock; 
                _flags &= ~SubtreeFlag.Reset;
            } 
            else if (_currentClock == _rootClock) 
            {
                // We last saw the root clock, so we are done 
                _currentClock = null;
            }

            // Skip trying to iterate if we are already past the end 
            if (_currentClock != null)
            { 
                Clock nextClock = _currentClock; 

                // The next clock is either our next sibling's first leaf 
                // or, if we don't have a sibling, our parent. If the current
                // clock is null, however, we are just starting, so skip this
                // move and go straight to the descent part
                if ((_currentClock != _rootClock) && (nextClock = _currentClock.NextSibling) == null) 
                {
                    // We have no siblings, so the next clock is our parent 
                    _currentClock = _currentClock.InternalParent; 
                }
                else 
                {
                    // We have a next sibling or we are the root. In either case, find the
                    // first leaf clock under this subtree
                    ClockGroup currentClockGroup; 
                    do
                    { 
                        _currentClock = nextClock; 
                        currentClockGroup = _currentClock as ClockGroup;
 
                    }
                    while ((nextClock = _currentClock.FirstChild) != null);
                }
 
                // Don't process the root, unless specifically requested
                if ((_currentClock == _rootClock) && ((_flags & SubtreeFlag.ProcessRoot) == 0)) 
                { 
                    _currentClock = null;
                } 
            }

            return _currentClock != null;
        } 

        #endregion // Methods 
 
        #region Properties
 
        /// 
        /// Gets the current element in the collection.
        /// 
        internal Clock Current 
        {
            get 
            { 
                return _currentClock;
            } 
        }

        #endregion // Properties
 
        #region Data
 
        private Clock       _rootClock; 
        private Clock       _currentClock;
        private SubtreeFlag _flags; 

        #endregion // Data
    }
 
    /// 
    /// An object that enumerates the timelines of a tree of Timeline 
    /// objects. 
    /// 
    [FriendAccessAllowed] // Built into Core, also used by Framework. 
    internal struct TimelineTreeEnumerator
    {
        #region Constructor
        ///  
        /// Creates an enumerator that iterates over a subtree of timelines
        /// in prefix order. 
        ///  
        /// 
        /// The timeline that is the root of the subtree to enumerate. 
        /// 
        /// 
        /// True to include the root in the enumeration, false otherwise.
        ///  
        internal TimelineTreeEnumerator(Timeline root, bool processRoot)
        { 
            _rootTimeline = root; 
            _flags = processRoot ? (SubtreeFlag.Reset | SubtreeFlag.ProcessRoot) : SubtreeFlag.Reset;
 
            // Start with stacks of capacity 10. That's relatively small, yet
            // it covers very large trees without reallocation of stack data.
            // Note that given the way we use the stacks we need one less entry
            // for indices than for timelines, as we don't care what the index 
            // of the root timeline is.
            _indexStack = new Stack(9); 
            _timelineStack = new Stack(10); 
        }
        #endregion // Constructor 

        #region Methods

        ///  
        /// Causes the enumerator to not enumerate the timelines in the subtree rooted
        /// at the current timeline. 
        ///  
        internal void SkipSubtree()
        { 
            _flags |= SubtreeFlag.SkipSubtree;
        }

        ///  
        /// Advances the enumerator to the next element of the collection.
        ///  
        ///  
        /// true if the enumerator was successfully advanced to the next element,
        /// false if the enumerator has passed the end of the collection. 
        /// 
        public bool MoveNext()
        {
            TimelineCollection  children; 

            // Get the iteration started in the right place, if we are just starting 
            if ((_flags & SubtreeFlag.Reset) != 0) 
            {
                // The reset flag takes effect only once 
                _flags &= ~SubtreeFlag.Reset;

                // We are just getting started. The first timeline is the root
                _timelineStack.Push(_rootTimeline); 

                // If we are not supposed to return the root, simply skip it 
                if ((_flags & SubtreeFlag.ProcessRoot) == 0) 
                {
                    MoveNext(); 
                }
            }
            else if (_timelineStack.Count > 0)
            { 
                // Only TimelineGroup can have children
                TimelineGroup timelineGroup = _timelineStack.Peek() as TimelineGroup; 
 
                // The next timeline is possibly the first child of the current timeline
                // If we have children move to the first one, unless we were 
                // asked to skip the subtree
                if (  ((_flags & SubtreeFlag.SkipSubtree) == 0)
                    && timelineGroup != null
                    && (children = timelineGroup.Children) != null 
                    && children.Count > 0
                    ) 
                { 
                    _timelineStack.Push(children[0]);
                    _indexStack.Push((int)0); 
                }
                else
                {
                    // The skip subtree flag takes effect only once 
                    _flags &= ~SubtreeFlag.SkipSubtree;
 
                    // Move to the first ancestor that has unvisited children, 
                    // then move to the first unvisited child. If we get to
                    // the root it means we are done. 
                    _timelineStack.Pop();
                    while (_timelineStack.Count > 0)
                    {
                        timelineGroup = _timelineStack.Peek() as TimelineGroup; 

                        // This has to be non-null since we already went down the tree 
                        children = timelineGroup.Children; 

                        int index = (int)_indexStack.Pop() + 1; 

                        if (index < children.Count)
                        {
                            // Move to the next child, and we are done 
                            _timelineStack.Push(children[index]);
                            _indexStack.Push(index); 
                            break; 
                        }
 
                        _timelineStack.Pop();
                    }
                }
            } 

            return _timelineStack.Count > 0; 
        } 

        #endregion // Methods 

        #region Properties

        ///  
        /// Gets the current element in the collection.
        ///  
        internal Timeline Current 
        {
            get 
            {
                return _timelineStack.Peek();
            }
        } 

        #endregion // Properties 
 
        #region Data
 
        private Timeline            _rootTimeline;
        private SubtreeFlag         _flags;
        private Stack               _indexStack;
        private Stack     _timelineStack; 

        #endregion // Data 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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