KeyedCollection.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Collections / ObjectModel / KeyedCollection.cs / 1305376 / KeyedCollection.cs
                        
                        
                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
// [....]
// 
 
namespace System.Collections.ObjectModel
{ 
    using System;
    using System.Collections.Generic;
    using System.Diagnostics;
    using System.Diagnostics.Contracts; 

    [Serializable] 
    [System.Runtime.InteropServices.ComVisible(false)] 
    [DebuggerTypeProxy(typeof(Mscorlib_KeyedCollectionDebugView<,>))]
    [DebuggerDisplay("Count = {Count}")] 
    public abstract class KeyedCollection: Collection
    {
        const int defaultThreshold = 0;
 
        IEqualityComparer comparer;
        Dictionary dict; 
        int keyCount; 
        int threshold;
 
        protected KeyedCollection(): this(null, defaultThreshold) {}

        protected KeyedCollection(IEqualityComparer comparer): this(comparer, defaultThreshold) {}
 

        protected KeyedCollection(IEqualityComparer comparer, int dictionaryCreationThreshold) { 
            if (comparer == null) { 
                comparer = EqualityComparer.Default;
            } 

            if (dictionaryCreationThreshold == -1) {
                dictionaryCreationThreshold = int.MaxValue;
            } 

            if( dictionaryCreationThreshold < -1) { 
                ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.dictionaryCreationThreshold, ExceptionResource.ArgumentOutOfRange_InvalidThreshold); 
            }
 
            this.comparer = comparer;
            this.threshold = dictionaryCreationThreshold;
        }
 
        public IEqualityComparer Comparer {
            get { 
                return comparer; 
            }
        } 

        public TItem this[TKey key] {
            get {
                if( key == null) { 
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key);
                } 
 
                if (dict != null) {
                    return dict[key]; 
                }

                foreach (TItem item in Items) {
                    if (comparer.Equals(GetKeyForItem(item), key)) return item; 
                }
 
                ThrowHelper.ThrowKeyNotFoundException(); 
                return default(TItem);
            } 
        }

        public bool Contains(TKey key) {
            if( key == null) { 
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key);
            } 
 
            if (dict != null) {
                return dict.ContainsKey(key); 
            }

            if (key != null) {
                foreach (TItem item in Items) { 
                    if (comparer.Equals(GetKeyForItem(item), key)) return true;
                } 
            } 
            return false;
        } 

        private bool ContainsItem(TItem item) {
            TKey key;
            if( (dict == null) || ((key = GetKeyForItem(item)) == null)) { 
                return Items.Contains(item);
            } 
 
            TItem itemInDict;
            bool exist = dict.TryGetValue(key, out itemInDict); 
            if( exist) {
                return EqualityComparer.Default.Equals(itemInDict, item);
            }
            return false; 
        }
 
        public bool Remove(TKey key) { 
            if( key == null) {
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key); 
            }

            if (dict != null) {
                if (dict.ContainsKey(key)) { 
                    return Remove(dict[key]);
                } 
 
                return false;
            } 

            if (key != null) {
                for (int i = 0; i < Items.Count; i++) {
                    if (comparer.Equals(GetKeyForItem(Items[i]), key)) { 
                        RemoveItem(i);
                        return true; 
                    } 
                }
            } 
            return false;
        }

        protected IDictionary Dictionary { 
            get { return dict; }
        } 
 
        protected void ChangeItemKey(TItem item, TKey newKey) {
            // check if the item exists in the collection 
            if( !ContainsItem(item)) {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_ItemNotExist);
            }
 
            TKey oldKey = GetKeyForItem(item);
            if (!comparer.Equals(oldKey, newKey)) { 
                if (newKey != null) { 
                    AddKey(newKey, item);
                } 

                if (oldKey != null) {
                    RemoveKey(oldKey);
                } 
            }
        } 
 
        protected override void ClearItems() {
            base.ClearItems(); 
            if (dict != null) {
                dict.Clear();
            }
 
            keyCount = 0;
        } 
 
        protected abstract TKey GetKeyForItem(TItem item);
 
        protected override void InsertItem(int index, TItem item) {
            TKey key = GetKeyForItem(item);
            if (key != null) {
                AddKey(key, item); 
            }
            base.InsertItem(index, item); 
        } 

        protected override void RemoveItem(int index) { 
            TKey key = GetKeyForItem(Items[index]);
            if (key != null) {
                RemoveKey(key);
            } 
            base.RemoveItem(index);
        } 
 
        protected override void SetItem(int index, TItem item) {
            TKey newKey = GetKeyForItem(item); 
            TKey oldKey = GetKeyForItem(Items[index]);

            if (comparer.Equals(oldKey, newKey)) {
                if (newKey != null && dict != null) { 
                    dict[newKey] = item;
                } 
            } 
            else {
                if (newKey != null) { 
                    AddKey(newKey, item);
                }

                if (oldKey != null) { 
                    RemoveKey(oldKey);
                } 
            } 
            base.SetItem(index, item);
        } 

        private void AddKey(TKey key, TItem item) {
            if (dict != null) {
                dict.Add(key, item); 
            }
            else if (keyCount == threshold) { 
                CreateDictionary(); 
                dict.Add(key, item);
            } 
            else {
                if (Contains(key)) {
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_AddingDuplicate);
                } 

                keyCount++; 
            } 
        }
 
        private void CreateDictionary() {
            dict = new Dictionary(comparer);
            foreach (TItem item in Items) {
                TKey key = GetKeyForItem(item); 
                if (key != null) {
                    dict.Add(key, item); 
                } 
            }
        } 

        private void RemoveKey(TKey key) {
            Contract.Assert(key != null, "key shouldn't be null!");
            if (dict != null) { 
                dict.Remove(key);
            } 
            else { 
                keyCount--;
            } 
        }
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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KeyedCollection.cs source code in C# .NET

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