CollectionViewGroupInternal.cs source code in C# .NET

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Code:

/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / MS / Internal / Data / CollectionViewGroupInternal.cs / 1458001 / CollectionViewGroupInternal.cs

                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) 2003 by Microsoft Corporation.  All rights reserved.
//  
//
// 
// Description: A CollectionViewGroupInternal, as created by a CollectionView according to a GroupDescription. 
//
// See spec at http://avalon/connecteddata/Specs/Grouping.mht 
//
//---------------------------------------------------------------------------

using System; 
using System.Collections;       // IEnumerator
using System.ComponentModel;    // PropertyChangedEventArgs, GroupDescription 
using System.Windows;           // DependencyProperty.UnsetValue 
using System.Windows.Data;      // CollectionViewGroup
 
namespace MS.Internal.Data
{
    internal class CollectionViewGroupInternal : CollectionViewGroup
    { 
        #region Constructors
 
        //----------------------------------------------------- 
        //
        //  Constructors 
        //
        //-----------------------------------------------------

        internal CollectionViewGroupInternal(object name, CollectionViewGroupInternal parent) : base(name) 
        {
            _parentGroup = parent; 
        } 

        #endregion Constructors 

        #region Public Properties

        //------------------------------------------------------ 
        //
        //  Public Properties 
        // 
        //-----------------------------------------------------
 
        /// 
        /// Is this group at the bottom level (not further subgrouped).
        /// 
        public override bool IsBottomLevel 
        {
            get { return (_groupBy == null); } 
        } 

        #endregion  Public Properties 

        #region Internal Properties

        //------------------------------------------------------ 
        //
        //  Internal Properties 
        // 
        //------------------------------------------------------
 
        // how this group divides into subgroups
        internal GroupDescription GroupBy
        {
            get { return _groupBy; } 
            set
            { 
                bool oldIsBottomLevel = IsBottomLevel; 

                if (_groupBy != null) 
                    ((INotifyPropertyChanged)_groupBy).PropertyChanged -= new PropertyChangedEventHandler(OnGroupByChanged);

                _groupBy = value;
 
                if (_groupBy != null)
                    ((INotifyPropertyChanged)_groupBy).PropertyChanged += new PropertyChangedEventHandler(OnGroupByChanged); 
 
                if (oldIsBottomLevel != IsBottomLevel)
                { 
                    OnPropertyChanged(new PropertyChangedEventArgs("IsBottomLevel"));
                }
            }
        } 

        // the number of items and groups in the subtree under this group 
        internal int FullCount 
        {
            get { return _fullCount; } 
            set { _fullCount = value; }
        }

        // the most recent index where actvity took place 
        internal int LastIndex
        { 
            get { return _lastIndex; } 
            set { _lastIndex = value; }
        } 

        // the first item (leaf) added to this group.  If this can't be determined,
        // DependencyProperty.UnsetValue.
        internal object SeedItem 
        {
            get 
            { 
                if (ItemCount > 0 && (GroupBy == null || GroupBy.GroupNames.Count == 0))
                { 
                    // look for first item, child by child
                    for (int k=0, n=Items.Count; k 0)
                        {
                            // child is a nonempty subgroup - ask it
                            return subgroup.SeedItem; 
                        }
                        // otherwise child is an empty subgroup - go to next child 
                    } 

                    // we shouldn't get here, but just in case... 
                    return DependencyProperty.UnsetValue;
                }
                else
                { 
                    // the group is empty, or it has explicit subgroups.
                    // In either case, we cannot determine the first item - 
                    // it could have gone into any of the subgroups. 
                    return DependencyProperty.UnsetValue;
                } 
            }
        }

        #endregion Properties 

        #region Internal methods 
 
        //-----------------------------------------------------
        // 
        //  Internal methods
        //
        //------------------------------------------------------
 
        internal void Add(object item)
        { 
            ChangeCounts(item, +1); 
            ProtectedItems.Add(item);
        } 

        internal int Remove(object item, bool returnLeafIndex)
        {
            int index = -1; 
            int localIndex = ProtectedItems.IndexOf(item);
 
            if (localIndex >= 0) 
            {
                if (returnLeafIndex) 
                {
                    index = LeafIndexFromItem(null, localIndex);
                }
 
                ChangeCounts(item, -1);
                ProtectedItems.RemoveAt(localIndex); 
            } 

            return index; 
        }

        internal void Clear()
        { 
            FullCount = 1;
            ProtectedItemCount = 0; 
            ProtectedItems.Clear(); 
        }
 
        // return the index of the given item within the list of leaves governed
        // by this group
        internal int LeafIndexOf(object item)
        { 
            int leaves = 0;         // number of leaves we've passed over so far
            for (int k=0, n=Items.Count;  k y
                    } 
                }
 
                // if we don't see either x or y, declare x > y. 
                // This has the effect of putting x at the end of the list.
                return + 1; 
            }

            int _index;
            IList _list; 
        }
 
        #endregion Internal Types 

        #region Private Properties 

        //-----------------------------------------------------
        //
        //  Private Properties 
        //
        //----------------------------------------------------- 
 
        private CollectionViewGroupInternal Parent
        { 
            get { return _parentGroup; }
        }

        #endregion Private Properties 

        #region Private methods 
 
        //-----------------------------------------------------
        // 
        //  Private methods
        //
        //------------------------------------------------------
 
        protected void ChangeCounts(object item, int delta)
        { 
            bool changeLeafCount = !(item is CollectionViewGroup); 

            for (   CollectionViewGroupInternal group = this; 
                    group != null;
                    group = group._parentGroup )
            {
                group.FullCount += delta; 
                if (changeLeafCount)
                { 
                    group.ProtectedItemCount += delta; 

                    if (group.ProtectedItemCount == 0) 
                    {
                        RemoveEmptyGroup(group);
                    }
                } 
            }
 
            unchecked {++_version;}     // this invalidates enumerators 
        }
 
        void RemoveEmptyGroup(CollectionViewGroupInternal group)
        {
            CollectionViewGroupInternal parent = group.Parent;
 
            if (parent != null)
            { 
                GroupDescription groupBy = parent.GroupBy; 
                int index = parent.ProtectedItems.IndexOf(group);
 
                // remove the subgroup unless it is one of the explicit groups
                if (index >= groupBy.GroupNames.Count)
                {
                    parent.Remove(group, false); 
                }
            } 
        } 

        void OnGroupByChanged(object sender, System.ComponentModel.PropertyChangedEventArgs e) 
        {
            OnGroupByChanged();
        }
 
        #endregion Private methods
 
        #region Private fields 

        //----------------------------------------------------- 
        //
        //  Private fields
        //
        //------------------------------------------------------ 

        GroupDescription    _groupBy; 
        CollectionViewGroupInternal _parentGroup; 
        int                 _fullCount = 1;
        int                 _lastIndex; 
        int                 _version;       // for detecting stale enumerators

        #endregion Private fields
 
        #region Private classes
 
        //------------------------------------------------------ 
        //
        //  Private classes 
        //
        //-----------------------------------------------------

        private class LeafEnumerator : IEnumerator 
        {
            public LeafEnumerator(CollectionViewGroupInternal group) 
            { 
                _group = group;
                DoReset();  // don't call virtual Reset in ctor 
            }

            void IEnumerator.Reset()
            { 
                DoReset();
            } 
 
            void DoReset()
            { 
                _version = _group._version;
                _index = -1;
                _subEnum = null;
            } 

            bool IEnumerator.MoveNext() 
            { 
                // check for invalidated enumerator
                if (_group._version != _version) 
                    throw new InvalidOperationException();

                // move forward to the next leaf
                while (_subEnum == null || !_subEnum.MoveNext()) 
                {
                    // done with the current top-level item.  Move to the next one. 
                    ++ _index; 
                    if (_index >= _group.Items.Count)
                        return false; 

                    CollectionViewGroupInternal subgroup = _group.Items[_index] as CollectionViewGroupInternal;
                    if (subgroup == null)
                    { 
                        // current item is a leaf - it's the new Current
                        _current = _group.Items[_index]; 
                        _subEnum = null; 
                        return true;
                    } 
                    else
                    {
                        // current item is a subgroup - get its enumerator
                        _subEnum = subgroup.GetLeafEnumerator(); 
                    }
                } 
 
                // the loop terminates only when we have a subgroup enumerator
                // positioned at the new Current item 
                _current = _subEnum.Current;
                return true;
            }
 
            object IEnumerator.Current
            { 
                get 
                {
                    if (_index < 0  ||  _index >= _group.Items.Count) 
                        throw new InvalidOperationException();
                    return _current;
                }
            } 

            CollectionViewGroupInternal _group; // parent group 
            int                 _version;   // parent group's version at ctor 
            int                 _index;     // current index into Items
            IEnumerator         _subEnum;   // enumerator over current subgroup 
            object              _current;   // current item
        }

        #endregion Private classes 
    }
 
} 

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

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