XamlContextStack.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Shared / MS / Internal / Xaml / Context / XamlContextStack.cs / 1305600 / XamlContextStack.cs
                        
                        
                            using System; 
using System.Collections.Generic;
using System.Text;
using System.Diagnostics;
using System.Globalization; 

namespace MS.Internal.Xaml.Context 
{ 
    //This stack has the following features:
    //  1) it recycles frames 
    //  2) it is , and avoids activator.createinstance with the creationDelegate
    class XamlContextStack where T : XamlFrame
    {
        private int _depth = -1; 
        T _currentFrame = null;
        T _recycledFrame = null; 
        Func _creationDelegate; 

        public XamlContextStack(Func creationDelegate) 
        {
            _creationDelegate = creationDelegate;
            Grow();
            _depth = 0; 
            Debug.Assert(CurrentFrame != null);
            Debug.Assert(CurrentFrame.Depth == Depth); 
        } 

        public XamlContextStack(XamlContextStack source, bool copy) 
        {
            _creationDelegate = source._creationDelegate;
            _depth = source.Depth;
            if (!copy) 
            {
                _currentFrame = source.CurrentFrame; 
            } 
            else
            { 
                T iteratorFrame = source.CurrentFrame;
                T lastFrameInNewStack = null;
                while (iteratorFrame != null)
                { 
                    T newFrame = (T)iteratorFrame.Clone();
                    if (_currentFrame == null) 
                    { 
                        _currentFrame = newFrame;
                    } 
                    if (lastFrameInNewStack != null)
                    {
                        lastFrameInNewStack.Previous = newFrame;
                    } 
                    lastFrameInNewStack = newFrame;
                    iteratorFrame = (T)iteratorFrame.Previous; 
                } 
            }
        } 

        //allocate a new frame as the new currentFrame;
        private void Grow()
        { 
            T lastFrame = _currentFrame;
            _currentFrame = _creationDelegate(); 
            _currentFrame.Previous = lastFrame; 
        }
 
        public T CurrentFrame
        {
            get { return _currentFrame; }
        } 

        public T PreviousFrame 
        { 
            get { return (T)_currentFrame.Previous; }
        } 

        public T PreviousPreviousFrame
        {
            get { return (T)_currentFrame.Previous.Previous; } 
        }
 
        public T GetFrame(int depth) 
        {
            T iteratorFrame = _currentFrame; 
            Debug.Assert(iteratorFrame != null);
            while (iteratorFrame.Depth > depth)
            {
                iteratorFrame = (T)iteratorFrame.Previous; 
            }
            return iteratorFrame; 
        } 

        //Consumers of this stack call PushScope, and we'll either allocate a new frame 
        // or we'll grab one from our recycled linked list.
        public void PushScope()
        {
            if (_recycledFrame == null) 
            {
                Grow(); 
            } 
            else //use recycled frame
            { 
                T lastFrame = _currentFrame;
                _currentFrame = _recycledFrame;
                _recycledFrame = (T)_recycledFrame.Previous;
                _currentFrame.Previous = lastFrame; 
            }
            _depth++; 
            Debug.Assert(CurrentFrame.Depth == Depth); 
        }
 
        //Consumers of this stack call PopScope, and we'll move the currentFrame from the main
        // linked list to the recylced linked list and call .Reset
        public void PopScope()
        { 
            _depth--;
            T frameToRecycle = _currentFrame; 
            _currentFrame = (T)_currentFrame.Previous; 
            frameToRecycle.Previous = _recycledFrame;
            _recycledFrame = frameToRecycle; 
            frameToRecycle.Reset();
            Debug.Assert(CurrentFrame.Depth == Depth);
        }
 
        public int Depth
        { 
            get { return _depth; } 
            set { _depth = value; }
        } 

        //In case the stack needs to survive and you don't want to keep the recylced frames around.
        public void Trim()
        { 
            _recycledFrame = null;
        } 
 
        public string Frames
        { 
            get
            {
                StringBuilder sb = new StringBuilder();
                T iteratorFrame = _currentFrame; 
                sb.AppendLine("Stack: " + (_currentFrame == null ? -1 : _currentFrame.Depth + 1).ToString(CultureInfo.InvariantCulture) + " frames");
                ShowFrame(sb, _currentFrame); 
                return sb.ToString(); 
            }
        } 

        private void ShowFrame(StringBuilder sb, T iteratorFrame)
        {
            if (iteratorFrame == null) 
                return;
            if (iteratorFrame.Previous != null) 
                ShowFrame(sb, (T)iteratorFrame.Previous); 
            sb.AppendLine("  " + iteratorFrame.Depth + " " + iteratorFrame.ToString());
        } 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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XamlContextStack.cs source code in C# .NET

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