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Categories / C# / Collections Data Structure

 

Scoped Dictionary

namespace Ngs.Collections {     // Copyright (c) Microsoft Corporation.  All rights reserved.     // This source code is made available under the terms of the Microsoft Public License (MS-PL)     using System;     using System.Collections;     using System.Collections.Generic;     public class ScopedDictionary<TKey, TValue>     {         ScopedDictionary<TKey, TValue> previous;         Dictionary<TKey, TValue> map;         public ScopedDictionary(ScopedDictionary<TKey, TValue> previous)         {             this.previous = previous;             this.map = new Dictionary<TKey, TValue>();         }         public ScopedDictionary(ScopedDictionary<TKey, TValue> previous, IEnumerable<KeyValuePair<TKey, TValue>> pairs)             : this(previous)         {             foreach (var p in pairs)             {                 this.map.Add(p.Key, p.Value);             }         }         public void Add(TKey key, TValue value)         {             this.map.Add(key, value);         }         public bool TryGetValue(TKey key, out TValue value)         {             for (ScopedDictionary<TKey, TValue> scope = this; scope != null; scope = scope.previous)             {                 if (scope.map.TryGetValue(key, out value))                     return true;             }             value = default(TValue);             return false;         }         public bool ContainsKey(TKey key)         {             for (ScopedDictionary<TKey, TValue> scope = this; scope != null; scope = scope.previous)             {                 if (scope.map.ContainsKey(key))                     return true;             }             return false;         }     } }