silverlight-简单ObservableDictionary

忽然觉得ObservableDictionary好像很有用，只是sl里好像没有，算了，自己写一个吧，bug未知，性能未知。

    public class ObservableDictionary<TKey, TValue> : Dictionary<TKey, TValue>, INotifyCollectionChanged

    {

        public event NotifyCollectionChangedEventHandler CollectionChanged;



        private int _index;



        public new TValue this[TKey key]

        {

            get { return this.GetValue(key); }

            set { this.SetValue(key, value); }

        }



        public new void Add(TKey key, TValue value)

        {

            base.Add(key, value);

            this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Add, this.FindPair(key), _index));

        }



        public new void Clear()

        {

            base.Clear();

            this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Reset));

        }



        public new bool Remove(TKey key)

        {

            var pair = this.FindPair(key);

            if (base.Remove(key))

            {

                this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Remove, pair, _index));

                return true;

            }

            return false;

        }



        private TValue GetValue(TKey key)

        {

            if (ContainsKey(key))

                return base[key];

            else

                return default(TValue);

        }



        private void SetValue(TKey key, TValue value)

        {

            if (ContainsKey(key))

            {

                base[key] = value;

                var pair = this.FindPair(key);

                var index = _index;

                this.OnCollectionChanged(new NotifyCollectionChangedEventArgs(NotifyCollectionChangedAction.Replace, pair, pair, index));

            }

            else

            {

                this.Add(key, value);

            }

        }



        private KeyValuePair<TKey, TValue> FindPair(TKey key)

        {

            _index = 0;

            foreach (var pair in this)

            {

                if (pair.Key.Equals(key))

                    return pair;



                _index++;

            }

            return default(KeyValuePair<TKey, TValue>);

        }



        private void OnCollectionChanged(NotifyCollectionChangedEventArgs e)

        {

            if (this.CollectionChanged != null)

            {

                this.CollectionChanged(this, e);

            }

        }

    }