OrderedDictionary.cs source code in C# .NET

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/ Dotnetfx_Vista_SP2 / Dotnetfx_Vista_SP2 / 8.0.50727.4016 / DEVDIV / depot / DevDiv / releases / whidbey / NetFxQFE / ndp / fx / src / CompMod / System / Collections / Specialized / OrderedDictionary.cs / 1 / OrderedDictionary.cs

                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

namespace System.Collections.Specialized { 
 
    using System;
    using System.Collections; 
    using System.Runtime.Serialization;
    using System.Security.Permissions;

    ///  
    /// 
    /// OrderedDictionary offers IDictionary syntax with ordering.  Objects 
    /// added or inserted in an IOrderedDictionary must have both a key and an index, and 
    /// can be retrieved by either.
    /// OrderedDictionary is used by the ParameterCollection because MSAccess relies on ordering of 
    /// parameters, while almost all other DBs do not.  DataKeyArray also uses it so
    /// DataKeys can be retrieved by either their name or their index.
    ///
    /// OrderedDictionary implements IDeserializationCallback because it needs to have the 
    /// contained ArrayList and Hashtable deserialized before it tries to get its count and objects.
    ///  
    ///  
    [Serializable]
    public class OrderedDictionary : IOrderedDictionary, ISerializable, IDeserializationCallback { 

        private ArrayList _objectsArray;
        private Hashtable _objectsTable;
        private int _initialCapacity; 
        private IEqualityComparer _comparer;
        private bool _readOnly; 
        private Object _syncRoot; 
        private SerializationInfo _siInfo; //A temporary variable which we need during deserialization.
 
        private const string KeyComparerName = "KeyComparer";
        private const string ArrayListName = "ArrayList";
        private const string ReadOnlyName = "ReadOnly";
        private const string InitCapacityName = "InitialCapacity"; 

        public OrderedDictionary() : this(0) { 
        } 

        public OrderedDictionary(int capacity) : this(capacity, null) { 
        }

        public OrderedDictionary(IEqualityComparer comparer) : this(0, comparer) {
        } 

        public OrderedDictionary(int capacity, IEqualityComparer comparer) { 
            _initialCapacity = capacity; 
            _comparer = comparer;
        } 

        private OrderedDictionary(OrderedDictionary dictionary) {
            if (dictionary == null) {
                throw new ArgumentNullException("dictionary"); 
            }
 
            _readOnly = true; 
            _objectsArray = dictionary._objectsArray;
            _objectsTable = dictionary._objectsTable; 
            _comparer = dictionary._comparer;
            _initialCapacity = dictionary._initialCapacity;
        }
 
        protected OrderedDictionary(SerializationInfo info, StreamingContext context) {
            // We can't do anything with the keys and values until the entire graph has been deserialized 
            // and getting Counts and objects won't fail.  For the time being, we'll just cache this. 
            // The graph is not valid until OnDeserialization has been called.
            _siInfo = info; 
        }

        /// 
        /// Gets the size of the table. 
        /// 
        public int Count { 
            get { 
                return objectsArray.Count;
            } 
        }

        /// 
        /// Indicates that the collection can grow. 
        /// 
        bool IDictionary.IsFixedSize { 
            get { 
                return _readOnly;
            } 
        }

        /// 
        /// Indicates that the collection is not read-only 
        /// 
        public bool IsReadOnly { 
            get { 
                return _readOnly;
            } 
        }

        /// 
        /// Indicates that this class is not synchronized 
        /// 
        bool ICollection.IsSynchronized { 
            get { 
                return false;
            } 
        }

        /// 
        /// Gets the collection of keys in the table in order. 
        /// 
        public ICollection Keys { 
            get { 
                return new OrderedDictionaryKeyValueCollection(objectsArray, true);
            } 
        }

        private ArrayList objectsArray {
            get { 
                if (_objectsArray == null) {
                    _objectsArray = new ArrayList(_initialCapacity); 
                } 
                return _objectsArray;
            } 
        }

        private Hashtable objectsTable {
            get { 
                if (_objectsTable == null) {
                    _objectsTable = new Hashtable(_initialCapacity, _comparer); 
                } 
                return _objectsTable;
            } 
        }

        /// 
        /// The SyncRoot object.  Not used because IsSynchronized is false 
        /// 
        object ICollection.SyncRoot { 
            get { 
                if (_syncRoot == null) {
                    System.Threading.Interlocked.CompareExchange(ref _syncRoot, new Object(), null); 
                }
                return _syncRoot;
            }
        } 

        ///  
        /// Gets or sets the object at the specified index 
        /// 
        public object this[int index] { 
            get {
                return ((DictionaryEntry)objectsArray[index]).Value;
            }
            set { 
                if (_readOnly) {
                    throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly)); 
                } 
                if (index < 0 || index >= objectsArray.Count) {
                    throw new ArgumentOutOfRangeException("index"); 
                }
                object key = ((DictionaryEntry)objectsArray[index]).Key;
                objectsArray[index] = new DictionaryEntry(key, value);
                objectsTable[key] = value; 
            }
        } 
 
        /// 
        /// Gets or sets the object with the specified key 
        /// 
        public object this[object key] {
            get {
                return objectsTable[key]; 
            }
            set { 
                if (_readOnly) { 
                    throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly));
                } 
                if (objectsTable.Contains(key)) {
                    objectsTable[key] = value;
                    objectsArray[IndexOfKey(key)] = new DictionaryEntry(key, value);
                } 
                else {
                    Add(key, value); 
                } 
            }
        } 

        /// 
        /// Returns an arrayList of the values in the table
        ///  
        public ICollection Values {
            get { 
                return new OrderedDictionaryKeyValueCollection(objectsArray, false); 
            }
        } 

        /// 
        /// Adds a new entry to the table with the lowest-available index.
        ///  
        public void Add(object key, object value) {
            if (_readOnly) { 
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly)); 
            }
            objectsTable.Add(key, value); 
            objectsArray.Add(new DictionaryEntry(key, value));
        }

        ///  
        /// Clears all elements in the table.
        ///  
        public void Clear() { 
            if (_readOnly) {
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly)); 
            }
            objectsTable.Clear();
            objectsArray.Clear();
        } 

        ///  
        /// Returns a readonly OrderedDictionary for the given OrderedDictionary. 
        /// 
        public OrderedDictionary AsReadOnly() { 
            return new OrderedDictionary(this);
        }

        ///  
        /// Returns true if the key exists in the table, false otherwise.
        ///  
        public bool Contains(object key) { 
            return objectsTable.Contains(key);
        } 

        /// 
        /// Copies the table to an array.  This will not preserve order.
        ///  
        public void CopyTo(Array array, int index) {
            objectsTable.CopyTo(array, index); 
        } 

        private int IndexOfKey(object key) { 
            for (int i = 0; i < objectsArray.Count; i++) {
                object o = ((DictionaryEntry)objectsArray[i]).Key;
                if (_comparer != null) {
                    if (_comparer.Equals(o, key)) { 
                        return i;
                    } 
                } 
                else {
                    if (o.Equals(key)) { 
                        return i;
                    }
                }
            } 
            return -1;
        } 
 
        /// 
        /// Inserts a new object at the given index with the given key. 
        /// 
        public void Insert(int index, object key, object value) {
            if (_readOnly) {
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly)); 
            }
            if (index > Count || index < 0) { 
                throw new ArgumentOutOfRangeException("index"); 
            }
            objectsTable.Add(key, value); 
            objectsArray.Insert(index, new DictionaryEntry(key, value));
        }

        ///  
        /// Handles the deserization event.  This method can be overridden.
        ///  
        protected virtual void OnDeserialization(object sender) { 
            if (_siInfo == null) {
                throw new SerializationException(SR.GetString(SR.Serialization_InvalidOnDeser)); 
            }
            _comparer = (IEqualityComparer)_siInfo.GetValue(KeyComparerName, typeof(IEqualityComparer));
            _readOnly = _siInfo.GetBoolean(ReadOnlyName);
            _initialCapacity = _siInfo.GetInt32(InitCapacityName); 

            object[] serArray = (object[])_siInfo.GetValue(ArrayListName, typeof(object[])); 
 
            if (serArray != null) {
                foreach (object o in serArray) { 
                    DictionaryEntry entry;
                    try {
                        // DictionaryEntry is a value type, so it can only be casted.
                        entry = (DictionaryEntry)o; 
                    }
                    catch { 
                        throw new SerializationException(SR.GetString(SR.OrderedDictionary_SerializationMismatch)); 
                    }
                    objectsArray.Add(entry); 
                    objectsTable.Add(entry.Key, entry.Value);
                }
            }
        } 

        ///  
        /// Removes the entry at the given index. 
        /// 
        public void RemoveAt(int index) { 
            if (_readOnly) {
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly));
            }
            if (index >= Count || index < 0) { 
                throw new ArgumentOutOfRangeException("index");
            } 
            object key = ((DictionaryEntry)objectsArray[index]).Key; 
            objectsArray.RemoveAt(index);
            objectsTable.Remove(key); 
        }

        /// 
        /// Removes the entry with the given key. 
        /// 
        public void Remove(object key) { 
            if (_readOnly) { 
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly));
            } 
            if (key == null) {
                throw new ArgumentNullException("key");
            }
 
            int index = IndexOfKey(key);
            if (index < 0) { 
                return; 
            }
 
            objectsTable.Remove(key);
            objectsArray.RemoveAt(index);
        }
 
        #region IDictionary implementation
        ///  
        public virtual IDictionaryEnumerator GetEnumerator() { 
            return new OrderedDictionaryEnumerator(objectsArray, OrderedDictionaryEnumerator.DictionaryEntry);
        } 
        #endregion

        #region IEnumerable implementation
        ///  
        IEnumerator IEnumerable.GetEnumerator() {
            return new OrderedDictionaryEnumerator(objectsArray, OrderedDictionaryEnumerator.DictionaryEntry); 
        } 
        #endregion
 
        #region ISerialization implementation
        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.SerializationFormatter)] 		
        public virtual void GetObjectData(SerializationInfo info, StreamingContext context) {
            if (info == null) { 
                throw new ArgumentNullException("info");
            } 
            info.AddValue(KeyComparerName, _comparer, typeof(IEqualityComparer)); 
            info.AddValue(ReadOnlyName, _readOnly);
            info.AddValue(InitCapacityName, _initialCapacity); 
            object[] serArray = new object[Count];
            _objectsArray.CopyTo(serArray);
            info.AddValue(ArrayListName, serArray);
        } 
        #endregion
 
        #region IDeserializationCallback implementation 
        void IDeserializationCallback.OnDeserialization(object sender) {
            OnDeserialization(sender); 
        }
        #endregion

        ///  
        /// OrderedDictionaryEnumerator works just like any other IDictionaryEnumerator, but it retrieves DictionaryEntries
        /// in the order by index. 
        ///  
        private class OrderedDictionaryEnumerator : IDictionaryEnumerator {
 
            private int _index = -1;
            private ArrayList _objects;
            private int _objectReturnType;
            internal const int Keys = 1; 
            internal const int Values = 2;
            internal const int DictionaryEntry = 3; 
 
            internal OrderedDictionaryEnumerator (ArrayList array, int objectReturnType) {
                _objects = array; 
                _objectReturnType = objectReturnType;
            }

            ///  
            /// Retrieves the current DictionaryEntry.  This is the same as Entry, but not strongly-typed.
            ///  
            public object Current { 
                get {
                    if (_objectReturnType == Keys) { 
                        return ((DictionaryEntry)_objects[_index]).Key;
                    }
                    if (_objectReturnType == Values) {
                        return ((DictionaryEntry)_objects[_index]).Value; 
                    }
                    return Entry; 
                } 
            }
 
            /// 
            /// Retrieves the current DictionaryEntry
            /// 
            public DictionaryEntry Entry { 
                get {
                    if (_index < 0 || _index >= _objects.Count) { 
                        throw new InvalidOperationException(); 
                    }
                    return new DictionaryEntry(((DictionaryEntry)_objects[_index]).Key, ((DictionaryEntry)_objects[_index]).Value); 
                }
            }

            ///  
            /// Retrieves the key of the current DictionaryEntry
            ///  
            public object Key { 
                get {
                    if (_index < 0 || _index >= _objects.Count) { 
                        throw new InvalidOperationException();
                    }
                    return ((DictionaryEntry)_objects[_index]).Key;
                } 
            }
 
            ///  
            /// Retrieves the value of the current DictionaryEntry
            ///  
            public object Value {
                get {
                    if (_index < 0 || _index >= _objects.Count) {
                        throw new InvalidOperationException(); 
                    }
                    return ((DictionaryEntry)_objects[_index]).Value; 
                } 
            }
 
            /// 
            /// Moves the enumerator pointer to the next member
            /// 
            public bool MoveNext() { 
                _index++;
                if (_index >= _objects.Count) { 
                    return false; 
                }
                return true; 
            }

            /// 
            /// Resets the enumerator pointer to the beginning. 
            /// 
            public void Reset() { 
                _index = -1; 
            }
        } 

        /// 
        /// OrderedDictionaryKeyValueCollection implements a collection for the Values and Keys properties
        /// that is "live"- it will reflect changes to the OrderedDictionary on the collection made after the getter 
        /// was called.
        ///  
        private class OrderedDictionaryKeyValueCollection : ICollection { 
            private ArrayList _objects;
            bool isKeys; 

            public OrderedDictionaryKeyValueCollection(ArrayList array, bool isKeys) {
                this._objects = array;
                this.isKeys = isKeys; 
            }
 
            void ICollection.CopyTo(Array array, int index)  { 
                if (array==null)
                    throw new ArgumentNullException("array"); 
                if (index < 0)
                    throw new ArgumentOutOfRangeException("index");
                foreach (object o in _objects) {
                    array.SetValue(isKeys ? ((DictionaryEntry)o).Key : ((DictionaryEntry)o).Value, index); 
                    index++;
                } 
            } 

            int ICollection.Count { 
                get {
                    return _objects.Count;
                }
            } 

            bool ICollection.IsSynchronized { 
                get { 
                    return false;
                } 
            }

            object ICollection.SyncRoot {
                get { 
                    return _objects.SyncRoot;
                } 
            } 

            IEnumerator IEnumerable.GetEnumerator() { 
                return new OrderedDictionaryEnumerator(_objects, isKeys == true ? OrderedDictionaryEnumerator.Keys : OrderedDictionaryEnumerator.Values);
            }
        }
    } 
}
 

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

namespace System.Collections.Specialized { 
 
    using System;
    using System.Collections; 
    using System.Runtime.Serialization;
    using System.Security.Permissions;

    ///  
    /// 
    /// OrderedDictionary offers IDictionary syntax with ordering.  Objects 
    /// added or inserted in an IOrderedDictionary must have both a key and an index, and 
    /// can be retrieved by either.
    /// OrderedDictionary is used by the ParameterCollection because MSAccess relies on ordering of 
    /// parameters, while almost all other DBs do not.  DataKeyArray also uses it so
    /// DataKeys can be retrieved by either their name or their index.
    ///
    /// OrderedDictionary implements IDeserializationCallback because it needs to have the 
    /// contained ArrayList and Hashtable deserialized before it tries to get its count and objects.
    ///  
    ///  
    [Serializable]
    public class OrderedDictionary : IOrderedDictionary, ISerializable, IDeserializationCallback { 

        private ArrayList _objectsArray;
        private Hashtable _objectsTable;
        private int _initialCapacity; 
        private IEqualityComparer _comparer;
        private bool _readOnly; 
        private Object _syncRoot; 
        private SerializationInfo _siInfo; //A temporary variable which we need during deserialization.
 
        private const string KeyComparerName = "KeyComparer";
        private const string ArrayListName = "ArrayList";
        private const string ReadOnlyName = "ReadOnly";
        private const string InitCapacityName = "InitialCapacity"; 

        public OrderedDictionary() : this(0) { 
        } 

        public OrderedDictionary(int capacity) : this(capacity, null) { 
        }

        public OrderedDictionary(IEqualityComparer comparer) : this(0, comparer) {
        } 

        public OrderedDictionary(int capacity, IEqualityComparer comparer) { 
            _initialCapacity = capacity; 
            _comparer = comparer;
        } 

        private OrderedDictionary(OrderedDictionary dictionary) {
            if (dictionary == null) {
                throw new ArgumentNullException("dictionary"); 
            }
 
            _readOnly = true; 
            _objectsArray = dictionary._objectsArray;
            _objectsTable = dictionary._objectsTable; 
            _comparer = dictionary._comparer;
            _initialCapacity = dictionary._initialCapacity;
        }
 
        protected OrderedDictionary(SerializationInfo info, StreamingContext context) {
            // We can't do anything with the keys and values until the entire graph has been deserialized 
            // and getting Counts and objects won't fail.  For the time being, we'll just cache this. 
            // The graph is not valid until OnDeserialization has been called.
            _siInfo = info; 
        }

        /// 
        /// Gets the size of the table. 
        /// 
        public int Count { 
            get { 
                return objectsArray.Count;
            } 
        }

        /// 
        /// Indicates that the collection can grow. 
        /// 
        bool IDictionary.IsFixedSize { 
            get { 
                return _readOnly;
            } 
        }

        /// 
        /// Indicates that the collection is not read-only 
        /// 
        public bool IsReadOnly { 
            get { 
                return _readOnly;
            } 
        }

        /// 
        /// Indicates that this class is not synchronized 
        /// 
        bool ICollection.IsSynchronized { 
            get { 
                return false;
            } 
        }

        /// 
        /// Gets the collection of keys in the table in order. 
        /// 
        public ICollection Keys { 
            get { 
                return new OrderedDictionaryKeyValueCollection(objectsArray, true);
            } 
        }

        private ArrayList objectsArray {
            get { 
                if (_objectsArray == null) {
                    _objectsArray = new ArrayList(_initialCapacity); 
                } 
                return _objectsArray;
            } 
        }

        private Hashtable objectsTable {
            get { 
                if (_objectsTable == null) {
                    _objectsTable = new Hashtable(_initialCapacity, _comparer); 
                } 
                return _objectsTable;
            } 
        }

        /// 
        /// The SyncRoot object.  Not used because IsSynchronized is false 
        /// 
        object ICollection.SyncRoot { 
            get { 
                if (_syncRoot == null) {
                    System.Threading.Interlocked.CompareExchange(ref _syncRoot, new Object(), null); 
                }
                return _syncRoot;
            }
        } 

        ///  
        /// Gets or sets the object at the specified index 
        /// 
        public object this[int index] { 
            get {
                return ((DictionaryEntry)objectsArray[index]).Value;
            }
            set { 
                if (_readOnly) {
                    throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly)); 
                } 
                if (index < 0 || index >= objectsArray.Count) {
                    throw new ArgumentOutOfRangeException("index"); 
                }
                object key = ((DictionaryEntry)objectsArray[index]).Key;
                objectsArray[index] = new DictionaryEntry(key, value);
                objectsTable[key] = value; 
            }
        } 
 
        /// 
        /// Gets or sets the object with the specified key 
        /// 
        public object this[object key] {
            get {
                return objectsTable[key]; 
            }
            set { 
                if (_readOnly) { 
                    throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly));
                } 
                if (objectsTable.Contains(key)) {
                    objectsTable[key] = value;
                    objectsArray[IndexOfKey(key)] = new DictionaryEntry(key, value);
                } 
                else {
                    Add(key, value); 
                } 
            }
        } 

        /// 
        /// Returns an arrayList of the values in the table
        ///  
        public ICollection Values {
            get { 
                return new OrderedDictionaryKeyValueCollection(objectsArray, false); 
            }
        } 

        /// 
        /// Adds a new entry to the table with the lowest-available index.
        ///  
        public void Add(object key, object value) {
            if (_readOnly) { 
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly)); 
            }
            objectsTable.Add(key, value); 
            objectsArray.Add(new DictionaryEntry(key, value));
        }

        ///  
        /// Clears all elements in the table.
        ///  
        public void Clear() { 
            if (_readOnly) {
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly)); 
            }
            objectsTable.Clear();
            objectsArray.Clear();
        } 

        ///  
        /// Returns a readonly OrderedDictionary for the given OrderedDictionary. 
        /// 
        public OrderedDictionary AsReadOnly() { 
            return new OrderedDictionary(this);
        }

        ///  
        /// Returns true if the key exists in the table, false otherwise.
        ///  
        public bool Contains(object key) { 
            return objectsTable.Contains(key);
        } 

        /// 
        /// Copies the table to an array.  This will not preserve order.
        ///  
        public void CopyTo(Array array, int index) {
            objectsTable.CopyTo(array, index); 
        } 

        private int IndexOfKey(object key) { 
            for (int i = 0; i < objectsArray.Count; i++) {
                object o = ((DictionaryEntry)objectsArray[i]).Key;
                if (_comparer != null) {
                    if (_comparer.Equals(o, key)) { 
                        return i;
                    } 
                } 
                else {
                    if (o.Equals(key)) { 
                        return i;
                    }
                }
            } 
            return -1;
        } 
 
        /// 
        /// Inserts a new object at the given index with the given key. 
        /// 
        public void Insert(int index, object key, object value) {
            if (_readOnly) {
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly)); 
            }
            if (index > Count || index < 0) { 
                throw new ArgumentOutOfRangeException("index"); 
            }
            objectsTable.Add(key, value); 
            objectsArray.Insert(index, new DictionaryEntry(key, value));
        }

        ///  
        /// Handles the deserization event.  This method can be overridden.
        ///  
        protected virtual void OnDeserialization(object sender) { 
            if (_siInfo == null) {
                throw new SerializationException(SR.GetString(SR.Serialization_InvalidOnDeser)); 
            }
            _comparer = (IEqualityComparer)_siInfo.GetValue(KeyComparerName, typeof(IEqualityComparer));
            _readOnly = _siInfo.GetBoolean(ReadOnlyName);
            _initialCapacity = _siInfo.GetInt32(InitCapacityName); 

            object[] serArray = (object[])_siInfo.GetValue(ArrayListName, typeof(object[])); 
 
            if (serArray != null) {
                foreach (object o in serArray) { 
                    DictionaryEntry entry;
                    try {
                        // DictionaryEntry is a value type, so it can only be casted.
                        entry = (DictionaryEntry)o; 
                    }
                    catch { 
                        throw new SerializationException(SR.GetString(SR.OrderedDictionary_SerializationMismatch)); 
                    }
                    objectsArray.Add(entry); 
                    objectsTable.Add(entry.Key, entry.Value);
                }
            }
        } 

        ///  
        /// Removes the entry at the given index. 
        /// 
        public void RemoveAt(int index) { 
            if (_readOnly) {
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly));
            }
            if (index >= Count || index < 0) { 
                throw new ArgumentOutOfRangeException("index");
            } 
            object key = ((DictionaryEntry)objectsArray[index]).Key; 
            objectsArray.RemoveAt(index);
            objectsTable.Remove(key); 
        }

        /// 
        /// Removes the entry with the given key. 
        /// 
        public void Remove(object key) { 
            if (_readOnly) { 
                throw new NotSupportedException(SR.GetString(SR.OrderedDictionary_ReadOnly));
            } 
            if (key == null) {
                throw new ArgumentNullException("key");
            }
 
            int index = IndexOfKey(key);
            if (index < 0) { 
                return; 
            }
 
            objectsTable.Remove(key);
            objectsArray.RemoveAt(index);
        }
 
        #region IDictionary implementation
        ///  
        public virtual IDictionaryEnumerator GetEnumerator() { 
            return new OrderedDictionaryEnumerator(objectsArray, OrderedDictionaryEnumerator.DictionaryEntry);
        } 
        #endregion

        #region IEnumerable implementation
        ///  
        IEnumerator IEnumerable.GetEnumerator() {
            return new OrderedDictionaryEnumerator(objectsArray, OrderedDictionaryEnumerator.DictionaryEntry); 
        } 
        #endregion
 
        #region ISerialization implementation
        [SecurityPermissionAttribute(SecurityAction.LinkDemand, Flags=SecurityPermissionFlag.SerializationFormatter)] 		
        public virtual void GetObjectData(SerializationInfo info, StreamingContext context) {
            if (info == null) { 
                throw new ArgumentNullException("info");
            } 
            info.AddValue(KeyComparerName, _comparer, typeof(IEqualityComparer)); 
            info.AddValue(ReadOnlyName, _readOnly);
            info.AddValue(InitCapacityName, _initialCapacity); 
            object[] serArray = new object[Count];
            _objectsArray.CopyTo(serArray);
            info.AddValue(ArrayListName, serArray);
        } 
        #endregion
 
        #region IDeserializationCallback implementation 
        void IDeserializationCallback.OnDeserialization(object sender) {
            OnDeserialization(sender); 
        }
        #endregion

        ///  
        /// OrderedDictionaryEnumerator works just like any other IDictionaryEnumerator, but it retrieves DictionaryEntries
        /// in the order by index. 
        ///  
        private class OrderedDictionaryEnumerator : IDictionaryEnumerator {
 
            private int _index = -1;
            private ArrayList _objects;
            private int _objectReturnType;
            internal const int Keys = 1; 
            internal const int Values = 2;
            internal const int DictionaryEntry = 3; 
 
            internal OrderedDictionaryEnumerator (ArrayList array, int objectReturnType) {
                _objects = array; 
                _objectReturnType = objectReturnType;
            }

            ///  
            /// Retrieves the current DictionaryEntry.  This is the same as Entry, but not strongly-typed.
            ///  
            public object Current { 
                get {
                    if (_objectReturnType == Keys) { 
                        return ((DictionaryEntry)_objects[_index]).Key;
                    }
                    if (_objectReturnType == Values) {
                        return ((DictionaryEntry)_objects[_index]).Value; 
                    }
                    return Entry; 
                } 
            }
 
            /// 
            /// Retrieves the current DictionaryEntry
            /// 
            public DictionaryEntry Entry { 
                get {
                    if (_index < 0 || _index >= _objects.Count) { 
                        throw new InvalidOperationException(); 
                    }
                    return new DictionaryEntry(((DictionaryEntry)_objects[_index]).Key, ((DictionaryEntry)_objects[_index]).Value); 
                }
            }

            ///  
            /// Retrieves the key of the current DictionaryEntry
            ///  
            public object Key { 
                get {
                    if (_index < 0 || _index >= _objects.Count) { 
                        throw new InvalidOperationException();
                    }
                    return ((DictionaryEntry)_objects[_index]).Key;
                } 
            }
 
            ///  
            /// Retrieves the value of the current DictionaryEntry
            ///  
            public object Value {
                get {
                    if (_index < 0 || _index >= _objects.Count) {
                        throw new InvalidOperationException(); 
                    }
                    return ((DictionaryEntry)_objects[_index]).Value; 
                } 
            }
 
            /// 
            /// Moves the enumerator pointer to the next member
            /// 
            public bool MoveNext() { 
                _index++;
                if (_index >= _objects.Count) { 
                    return false; 
                }
                return true; 
            }

            /// 
            /// Resets the enumerator pointer to the beginning. 
            /// 
            public void Reset() { 
                _index = -1; 
            }
        } 

        /// 
        /// OrderedDictionaryKeyValueCollection implements a collection for the Values and Keys properties
        /// that is "live"- it will reflect changes to the OrderedDictionary on the collection made after the getter 
        /// was called.
        ///  
        private class OrderedDictionaryKeyValueCollection : ICollection { 
            private ArrayList _objects;
            bool isKeys; 

            public OrderedDictionaryKeyValueCollection(ArrayList array, bool isKeys) {
                this._objects = array;
                this.isKeys = isKeys; 
            }
 
            void ICollection.CopyTo(Array array, int index)  { 
                if (array==null)
                    throw new ArgumentNullException("array"); 
                if (index < 0)
                    throw new ArgumentOutOfRangeException("index");
                foreach (object o in _objects) {
                    array.SetValue(isKeys ? ((DictionaryEntry)o).Key : ((DictionaryEntry)o).Value, index); 
                    index++;
                } 
            } 

            int ICollection.Count { 
                get {
                    return _objects.Count;
                }
            } 

            bool ICollection.IsSynchronized { 
                get { 
                    return false;
                } 
            }

            object ICollection.SyncRoot {
                get { 
                    return _objects.SyncRoot;
                } 
            } 

            IEnumerator IEnumerable.GetEnumerator() { 
                return new OrderedDictionaryEnumerator(_objects, isKeys == true ? OrderedDictionaryEnumerator.Keys : OrderedDictionaryEnumerator.Values);
            }
        }
    } 
}
 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

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