/DICK.B1/IronPython/Runtime/CustomDictionaryStorage.cs

/* ****************************************************************************

 *

 * Copyright (c) Microsoft Corporation. 

 *

 * This source code is subject to terms and conditions of the Microsoft Public License. A 

 * copy of the license can be found in the License.html file at the root of this distribution. If 

 * you cannot locate the  Microsoft Public License, please send an email to 

 * dlr@microsoft.com. By using this source code in any fashion, you are agreeing to be bound 

 * by the terms of the Microsoft Public License.

 *

 * You must not remove this notice, or any other, from this software.

 *

 *

 * ***************************************************************************/



using System;

using System.Collections.Generic;



using Microsoft.Scripting;

using Microsoft.Scripting.Runtime;



namespace IronPython.Runtime {

    abstract class CustomDictionaryStorage : DictionaryStorage {

        private readonly CommonDictionaryStorage/*!*/ _storage = new CommonDictionaryStorage();



        public override void Add(object key, object value) {

            if (key is string && TrySetExtraValue((string)key, value)) {

                return;

            }

            _storage.Add(key, value);

        }



        public override bool Contains(object key) {

            object dummy;

            if (key is string && TryGetExtraValue((string)key, out dummy)) {

                return dummy != Uninitialized.Instance;

            }



            return _storage.Contains(key);

        }



        public override bool Remove(object key) {

            if (key is string) {

                return TryRemoveExtraValue((string)key) ?? _storage.Remove(key);



            }

            return _storage.Remove(key);

        }



        public override bool TryGetValue(object key, out object value) {

            if (key is string && TryGetExtraValue((string)key, out value)) {

                return value != Uninitialized.Instance;

            }



            return _storage.TryGetValue(key, out value);

        }



        public override int Count {

            get { return GetItems().Count; }

        }



        public override void Clear() {

            _storage.Clear();

            foreach (var item in GetExtraItems()) {

                TryRemoveExtraValue(item.Key);

            }

        }



        public override List<KeyValuePair<object, object>> GetItems() {

            List<KeyValuePair<object, object>> res = _storage.GetItems();



            foreach (var item in GetExtraItems()) {

                res.Add(new KeyValuePair<object, object>(item.Key, item.Value));

            }



            return res;

        }



        /// <summary>

        /// Gets all of the extra names and values stored in the dictionary.

        /// </summary>

        protected abstract IEnumerable<KeyValuePair<string, object>> GetExtraItems();



        /// <summary>

        /// Attemps to sets a value in the extra keys.  Returns true if the value is set, false if 

        /// the value is not an extra key.

        /// </summary>

        protected abstract bool TrySetExtraValue(string key, object value);



        /// <summary>

        /// Attempts to get a value from the extra keys.  Returns true if the value is an extra

        /// key and has a value.  False if it is not an extra key or doesn't have a value.

        /// </summary>

        protected abstract bool TryGetExtraValue(string key, out object value);



        /// <summary>

        /// Attempts to remove the key.  Returns true if the key is removed, false

        /// if the key was not removed, or null if the key is not an extra key.

        /// </summary>

        protected abstract bool? TryRemoveExtraValue(string key);

    }

}