Dictionary.cs source code in C# .NET

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Code:

/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / clr / src / BCL / System / Collections / Generic / Dictionary.cs / 1305376 / Dictionary.cs

                            // ==++== 
//
//   Copyright (c) Microsoft Corporation.  All rights reserved.
//
// ==--== 
/*============================================================
** 
** Class:  Dictionary 
**
** [....] 
**
** Purpose: Generic hash table implementation
**
** #DictionaryVersusHashtableThreadSafety 
** Hashtable has multiple reader/single writer (MR/SW) thread safety built into
** certain methods and properties, whereas Dictionary doesn't. If you're 
** converting framework code that formerly used Hashtable to Dictionary, it's 
** important to consider whether callers may have taken a dependence on MR/SW
** thread safety. If a reader writer lock is available, then that may be used 
** with a Dictionary to get the same thread safety guarantee.
**
** Reader writer locks don't exist in silverlight, so we do the following as a
** result of removing non-generic collections from silverlight: 
** 1. If the Hashtable was fully synchronized, then we replace it with a
**    Dictionary with full locks around reads/writes (same thread safety 
**    guarantee). 
** 2. Otherwise, the Hashtable has the default MR/SW thread safety behavior,
**    so we do one of the following on a case-by-case basis: 
**    a. If the ---- can be addressed by rearranging the code and using a temp
**       variable (for example, it's only populated immediately after created)
**       then we address the ---- this way and use Dictionary.
**    b. If there's concern about degrading performance with the increased 
**       locking, we ifdef with FEATURE_NONGENERIC_COLLECTIONS so we can at
**       least use Hashtable in the desktop build, but Dictionary with full 
**       locks in silverlight builds. Note that this is heavier locking than 
**       MR/SW, but this is the only option without rewriting (or adding back)
**       the reader writer lock. 
**    c. If there's no performance concern (e.g. debug-only code) we
**       consistently replace Hashtable with Dictionary plus full locks to
**       reduce complexity.
**    d. Most of serialization is dead code in silverlight. Instead of updating 
**       those Hashtable occurences in serialization, we carved out references
**       to serialization such that this code doesn't need to build in 
**       silverlight. 
===========================================================*/
namespace System.Collections.Generic { 

    using System;
    using System.Collections;
    using System.Diagnostics; 
    using System.Diagnostics.Contracts;
    using System.Runtime.Serialization; 
    using System.Security.Permissions; 

    [DebuggerTypeProxy(typeof(Mscorlib_DictionaryDebugView<,>))] 
    [DebuggerDisplay("Count = {Count}")]
    [Serializable]
    [System.Runtime.InteropServices.ComVisible(false)]
    public class Dictionary: IDictionary, IDictionary, ISerializable, IDeserializationCallback  { 

        private struct Entry { 
            public int hashCode;    // Lower 31 bits of hash code, -1 if unused 
            public int next;        // Index of next entry, -1 if last
            public TKey key;           // Key of entry 
            public TValue value;         // Value of entry
        }

        private int[] buckets; 
        private Entry[] entries;
        private int count; 
        private int version; 
        private int freeList;
        private int freeCount; 
        private IEqualityComparer comparer;
        private KeyCollection keys;
        private ValueCollection values;
        private Object _syncRoot; 

        private SerializationInfo m_siInfo; //A temporary variable which we need during deserialization. 
 
        // constants for serialization
        private const String VersionName = "Version"; 
        private const String HashSizeName = "HashSize";  // Must save buckets.Length
        private const String KeyValuePairsName = "KeyValuePairs";
        private const String ComparerName = "Comparer";
 
        public Dictionary(): this(0, null) {}
 
        public Dictionary(int capacity): this(capacity, null) {} 

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

        public Dictionary(int capacity, IEqualityComparer comparer) {
            if (capacity < 0) ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.capacity);
            if (capacity > 0) Initialize(capacity); 
            this.comparer = comparer ?? EqualityComparer.Default;
        } 
 
        public Dictionary(IDictionary dictionary): this(dictionary, null) {}
 
        public Dictionary(IDictionary dictionary, IEqualityComparer comparer):
            this(dictionary != null? dictionary.Count: 0, comparer) {

            if( dictionary == null) { 
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.dictionary);
            } 
 
            foreach (KeyValuePair pair in dictionary) {
                Add(pair.Key, pair.Value); 
            }
        }

        protected Dictionary(SerializationInfo info, StreamingContext context) { 
            //We can't do anything with the keys and values until the entire graph has been deserialized
            //and we have a resonable estimate that GetHashCode is not going to fail.  For the time being, 
            //we'll just cache this.  The graph is not valid until OnDeserialization has been called. 
            m_siInfo = info;
        } 

        public IEqualityComparer Comparer {
            get {
                return comparer; 
            }
        } 
 
        public int Count {
            get { return count - freeCount; } 
        }

        public KeyCollection Keys {
            get { 
                Contract.Ensures(Contract.Result() != null);
                if (keys == null) keys = new KeyCollection(this); 
                return keys; 
            }
        } 

        ICollection IDictionary.Keys {
            get {
                if (keys == null) keys = new KeyCollection(this); 
                return keys;
            } 
        } 

        public ValueCollection Values { 
            get {
                Contract.Ensures(Contract.Result() != null);
                if (values == null) values = new ValueCollection(this);
                return values; 
            }
        } 
 
        ICollection IDictionary.Values {
            get { 
                if (values == null) values = new ValueCollection(this);
                return values;
            }
        } 

        public TValue this[TKey key] { 
            get { 
                int i = FindEntry(key);
                if (i >= 0) return entries[i].value; 
                ThrowHelper.ThrowKeyNotFoundException();
                return default(TValue);
            }
            set { 
                Insert(key, value, false);
            } 
        } 

        public void Add(TKey key, TValue value) { 
            Insert(key, value, true);
        }

        void ICollection>.Add(KeyValuePair keyValuePair) { 
            Add(keyValuePair.Key, keyValuePair.Value);
        } 
 
        bool ICollection>.Contains(KeyValuePair keyValuePair) {
            int i = FindEntry(keyValuePair.Key); 
            if( i >= 0 && EqualityComparer.Default.Equals(entries[i].value, keyValuePair.Value)) {
                return true;
            }
            return false; 
        }
 
        bool ICollection>.Remove(KeyValuePair keyValuePair) { 
            int i = FindEntry(keyValuePair.Key);
            if( i >= 0 && EqualityComparer.Default.Equals(entries[i].value, keyValuePair.Value)) { 
                Remove(keyValuePair.Key);
                return true;
            }
            return false; 
        }
 
        public void Clear() { 
            if (count > 0) {
                for (int i = 0; i < buckets.Length; i++) buckets[i] = -1; 
                Array.Clear(entries, 0, count);
                freeList = -1;
                count = 0;
                freeCount = 0; 
                version++;
            } 
        } 

        public bool ContainsKey(TKey key) { 
            return FindEntry(key) >= 0;
        }

        public bool ContainsValue(TValue value) { 
            if (value == null) {
                for (int i = 0; i < count; i++) { 
                    if (entries[i].hashCode >= 0 && entries[i].value == null) return true; 
                }
            } 
            else {
                EqualityComparer c = EqualityComparer.Default;
                for (int i = 0; i < count; i++) {
                    if (entries[i].hashCode >= 0 && c.Equals(entries[i].value, value)) return true; 
                }
            } 
            return false; 
        }
 
// This security annotation is present only because of tool issues. Annotations should be kept in the
// baseline xml files. Basically, don't copy this style of security annotation!
[System.Security.SecuritySafeCritical]
        private void CopyTo(KeyValuePair[] array, int index) { 
            if (array == null) {
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.array); 
            } 

            if (index < 0 || index > array.Length ) { 
                ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.index, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
            }

            if (array.Length - index < Count) { 
                ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_ArrayPlusOffTooSmall);
            } 
 
            int count = this.count;
            Entry[] entries = this.entries; 
            for (int i = 0; i < count; i++) {
                if (entries[i].hashCode >= 0) {
                    array[index++] = new KeyValuePair(entries[i].key, entries[i].value);
                } 
            }
        } 
 
        public Enumerator GetEnumerator() {
            return new Enumerator(this, Enumerator.KeyValuePair); 
        }

        IEnumerator> IEnumerable>.GetEnumerator() {
            return new Enumerator(this, Enumerator.KeyValuePair); 
        }
 
        [System.Security.SecurityCritical]  // auto-generated_required 
        public virtual void GetObjectData(SerializationInfo info, StreamingContext context) {
            if (info==null) { 
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.info);
            }
            info.AddValue(VersionName, version);
            info.AddValue(ComparerName, comparer, typeof(IEqualityComparer)); 
            info.AddValue(HashSizeName, buckets == null ? 0 : buckets.Length); //This is the length of the bucket array.
            if( buckets != null) { 
                KeyValuePair[] array = new KeyValuePair[Count]; 
                CopyTo(array, 0);
                info.AddValue(KeyValuePairsName, array, typeof(KeyValuePair[])); 
            }
        }

        private int FindEntry(TKey key) { 
            if( key == null) {
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key); 
            } 

            if (buckets != null) { 
                int hashCode = comparer.GetHashCode(key) & 0x7FFFFFFF;
                for (int i = buckets[hashCode % buckets.Length]; i >= 0; i = entries[i].next) {
                    if (entries[i].hashCode == hashCode && comparer.Equals(entries[i].key, key)) return i;
                } 
            }
            return -1; 
        } 

        private void Initialize(int capacity) { 
            int size = HashHelpers.GetPrime(capacity);
            buckets = new int[size];
            for (int i = 0; i < buckets.Length; i++) buckets[i] = -1;
            entries = new Entry[size]; 
            freeList = -1;
        } 
 
        private void Insert(TKey key, TValue value, bool add) {
 
            if( key == null ) {
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key);
            }
 
            if (buckets == null) Initialize(0);
            int hashCode = comparer.GetHashCode(key) & 0x7FFFFFFF; 
            int targetBucket = hashCode % buckets.Length; 
            for (int i = buckets[targetBucket]; i >= 0; i = entries[i].next) {
                if (entries[i].hashCode == hashCode && comparer.Equals(entries[i].key, key)) { 
                    if (add) {
                        ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_AddingDuplicate);
                    }
                    entries[i].value = value; 
                    version++;
                    return; 
                } 
            }
            int index; 
            if (freeCount > 0) {
                index = freeList;
                freeList = entries[index].next;
                freeCount--; 
            }
            else { 
                if (count == entries.Length) 
                {
                    Resize(); 
                    targetBucket = hashCode % buckets.Length;
                }
                index = count;
                count++; 
            }
 
            entries[index].hashCode = hashCode; 
            entries[index].next = buckets[targetBucket];
            entries[index].key = key; 
            entries[index].value = value;
            buckets[targetBucket] = index;
            version++;
        } 

        public virtual void OnDeserialization(Object sender) { 
            if (m_siInfo==null) { 
                // It might be necessary to call OnDeserialization from a container if the container object also implements
                // OnDeserialization. However, remoting will call OnDeserialization again. 
                // We can return immediately if this function is called twice.
                // Note we set m_siInfo to null at the end of this method.
                return;
            } 

            int realVersion = m_siInfo.GetInt32(VersionName); 
            int hashsize = m_siInfo.GetInt32(HashSizeName); 
            comparer   = (IEqualityComparer)m_siInfo.GetValue(ComparerName, typeof(IEqualityComparer));
 
            if( hashsize != 0) {
                buckets = new int[hashsize];
                for (int i = 0; i < buckets.Length; i++) buckets[i] = -1;
                entries = new Entry[hashsize]; 
                freeList = -1;
 
                KeyValuePair[] array = (KeyValuePair[]) 
                    m_siInfo.GetValue(KeyValuePairsName, typeof(KeyValuePair[]));
 
                if (array==null) {
                    ThrowHelper.ThrowSerializationException(ExceptionResource.Serialization_MissingKeys);
                }
 
                for (int i=0; i= 0; last = i, i = entries[i].next) {
                    if (entries[i].hashCode == hashCode && comparer.Equals(entries[i].key, key)) { 
                        if (last < 0) {
                            buckets[bucket] = entries[i].next;
                        }
                        else { 
                            entries[last].next = entries[i].next;
                        } 
                        entries[i].hashCode = -1; 
                        entries[i].next = freeList;
                        entries[i].key = default(TKey); 
                        entries[i].value = default(TValue);
                        freeList = i;
                        freeCount++;
                        version++; 
                        return true;
                    } 
                } 
            }
            return false; 
        }

        public bool TryGetValue(TKey key, out TValue value) {
            int i = FindEntry(key); 
            if (i >= 0) {
                value = entries[i].value; 
                return true; 
            }
            value = default(TValue); 
            return false;
        }

        // This is a convenience method for the internal callers that were converted from using Hashtable. 
        // Many were combining key doesn't exist and key exists but null value (for non-value types) checks.
        // This allows them to continue getting that behavior with minimal code delta. This is basically 
        // TryGetValue without the out param 
        internal TValue GetValueOrDefault(TKey key) {
            int i = FindEntry(key); 
            if (i >= 0) {
                return entries[i].value;
            }
            return default(TValue); 
        }
 
        bool ICollection>.IsReadOnly { 
            get { return false; }
        } 

        void ICollection>.CopyTo(KeyValuePair[] array, int index) {
            CopyTo(array, index);
        } 

        void ICollection.CopyTo(Array array, int index) { 
            if (array == null) { 
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.array);
            } 

            if (array.Rank != 1) {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_RankMultiDimNotSupported);
            } 

            if( array.GetLowerBound(0) != 0 ) { 
                ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_NonZeroLowerBound); 
            }
 
            if (index < 0 || index > array.Length) {
                ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.index, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
            }
 
            if (array.Length - index < Count) {
                ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_ArrayPlusOffTooSmall); 
            } 

            KeyValuePair[] pairs = array as KeyValuePair[]; 
            if (pairs != null) {
                CopyTo(pairs, index);
            }
            else if( array is DictionaryEntry[]) { 
                DictionaryEntry[] dictEntryArray = array as DictionaryEntry[];
                Entry[] entries = this.entries; 
                for (int i = 0; i < count; i++) { 
                    if (entries[i].hashCode >= 0) {
                        dictEntryArray[index++] = new DictionaryEntry(entries[i].key, entries[i].value); 
                    }
                }
            }
            else { 
                object[] objects = array as object[];
                if (objects == null) { 
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType); 
                }
 
                try {
                    int count = this.count;
                    Entry[] entries = this.entries;
                    for (int i = 0; i < count; i++) { 
                        if (entries[i].hashCode >= 0) {
                            objects[index++] = new KeyValuePair(entries[i].key, entries[i].value); 
                        } 
                    }
                } 
                catch(ArrayTypeMismatchException) {
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType);
                }
            } 
        }
 
        IEnumerator IEnumerable.GetEnumerator() { 
            return new Enumerator(this, Enumerator.KeyValuePair);
        } 

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

        object ICollection.SyncRoot { 
            get { 
                if( _syncRoot == null) {
                    System.Threading.Interlocked.CompareExchange(ref _syncRoot, new Object(), null); 
                }
                return _syncRoot;
            }
        } 

        bool IDictionary.IsFixedSize { 
            get { return false; } 
        }
 
        bool IDictionary.IsReadOnly {
            get { return false; }
        }
 
        ICollection IDictionary.Keys {
            get { return (ICollection)Keys; } 
        } 

        ICollection IDictionary.Values { 
            get { return (ICollection)Values; }
        }

        object IDictionary.this[object key] { 
            get {
                if( IsCompatibleKey(key)) { 
                    int i = FindEntry((TKey)key); 
                    if (i >= 0) {
                        return entries[i].value; 
                    }
                }
                return null;
            } 
            set {
                if (key == null) 
                { 
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key);
                } 
                ThrowHelper.IfNullAndNullsAreIllegalThenThrow(value, ExceptionArgument.value);

                try {
                    TKey tempKey = (TKey)key; 
                    try {
                        this[tempKey] = (TValue)value; 
                    } 
                    catch (InvalidCastException) {
                        ThrowHelper.ThrowWrongValueTypeArgumentException(value, typeof(TValue)); 
                    }
                }
                catch (InvalidCastException) {
                    ThrowHelper.ThrowWrongKeyTypeArgumentException(key, typeof(TKey)); 
                }
            } 
        } 

        private static bool IsCompatibleKey(object key) { 
            if( key == null) {
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key);
                }
            return (key is TKey); 
        }
 
        void IDictionary.Add(object key, object value) { 
            if (key == null)
            { 
                ThrowHelper.ThrowArgumentNullException(ExceptionArgument.key);
            }
            ThrowHelper.IfNullAndNullsAreIllegalThenThrow(value, ExceptionArgument.value);
 
            try {
                TKey tempKey = (TKey)key; 
 
                try {
                    Add(tempKey, (TValue)value); 
                }
                catch (InvalidCastException) {
                    ThrowHelper.ThrowWrongValueTypeArgumentException(value, typeof(TValue));
                } 
            }
            catch (InvalidCastException) { 
                ThrowHelper.ThrowWrongKeyTypeArgumentException(key, typeof(TKey)); 
            }
        } 

        bool IDictionary.Contains(object key) {
            if(IsCompatibleKey(key)) {
                return ContainsKey((TKey)key); 
            }
 
            return false; 
        }
 
        IDictionaryEnumerator IDictionary.GetEnumerator() {
            return new Enumerator(this, Enumerator.DictEntry);
        }
 
        void IDictionary.Remove(object key) {
            if(IsCompatibleKey(key)) { 
                Remove((TKey)key); 
            }
        } 

        [Serializable]
        public struct Enumerator: IEnumerator>,
            IDictionaryEnumerator 
        {
            private Dictionary dictionary; 
            private int version; 
            private int index;
            private KeyValuePair current; 
            private int getEnumeratorRetType;  // What should Enumerator.Current return?

            internal const int DictEntry = 1;
            internal const int KeyValuePair = 2; 

            internal Enumerator(Dictionary dictionary, int getEnumeratorRetType) { 
                this.dictionary = dictionary; 
                version = dictionary.version;
                index = 0; 
                this.getEnumeratorRetType = getEnumeratorRetType;
                current = new KeyValuePair();
            }
 
            public bool MoveNext() {
                if (version != dictionary.version) { 
                    ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion); 
                }
 
                // Use unsigned comparison since we set index to dictionary.count+1 when the enumeration ends.
                // dictionary.count+1 could be negative if dictionary.count is Int32.MaxValue
                while ((uint)index < (uint)dictionary.count) {
                    if (dictionary.entries[index].hashCode >= 0) { 
                        current = new KeyValuePair(dictionary.entries[index].key, dictionary.entries[index].value);
                        index++; 
                        return true; 
                    }
                    index++; 
                }

                index = dictionary.count + 1;
                current = new KeyValuePair(); 
                return false;
            } 
 
            public KeyValuePair Current {
                get { return current; } 
            }

            public void Dispose() {
            } 

            object IEnumerator.Current { 
                get { 
                    if( index == 0 || (index == dictionary.count + 1)) {
                        ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumOpCantHappen); 
                    }

                    if (getEnumeratorRetType == DictEntry) {
                        return new System.Collections.DictionaryEntry(current.Key, current.Value); 
                    } else {
                        return new KeyValuePair(current.Key, current.Value); 
                    } 
                }
            } 

            void IEnumerator.Reset() {
                if (version != dictionary.version) {
                    ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion); 
                }
 
                index = 0; 
                current = new KeyValuePair();
            } 

            DictionaryEntry IDictionaryEnumerator.Entry {
                get {
                    if( index == 0 || (index == dictionary.count + 1)) { 
                         ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumOpCantHappen);
                    } 
 
                    return new DictionaryEntry(current.Key, current.Value);
                } 
            }

            object IDictionaryEnumerator.Key {
                get { 
                    if( index == 0 || (index == dictionary.count + 1)) {
                         ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumOpCantHappen); 
                    } 

                    return current.Key; 
                }
            }

            object IDictionaryEnumerator.Value { 
                get {
                    if( index == 0 || (index == dictionary.count + 1)) { 
                         ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumOpCantHappen); 
                    }
 
                    return current.Value;
                }
            }
        } 

        [DebuggerTypeProxy(typeof(Mscorlib_DictionaryKeyCollectionDebugView<,>))] 
        [DebuggerDisplay("Count = {Count}")] 
        [Serializable]
        public sealed class KeyCollection: ICollection, ICollection 
        {
            private Dictionary dictionary;

            public KeyCollection(Dictionary dictionary) { 
                if (dictionary == null) {
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.dictionary); 
                } 
                this.dictionary = dictionary;
            } 

            public Enumerator GetEnumerator() {
                return new Enumerator(dictionary);
            } 

            public void CopyTo(TKey[] array, int index) { 
                if (array == null) { 
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.array);
                } 

                if (index < 0 || index > array.Length) {
                    ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.index, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
                } 

                if (array.Length - index < dictionary.Count) { 
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_ArrayPlusOffTooSmall); 
                }
 
                int count = dictionary.count;
                Entry[] entries = dictionary.entries;
                for (int i = 0; i < count; i++) {
                    if (entries[i].hashCode >= 0) array[index++] = entries[i].key; 
                }
            } 
 
            public int Count {
                get { return dictionary.Count; } 
            }

            bool ICollection.IsReadOnly {
                get { return true; } 
            }
 
            void ICollection.Add(TKey item){ 
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_KeyCollectionSet);
            } 

            void ICollection.Clear(){
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_KeyCollectionSet);
            } 

            bool ICollection.Contains(TKey item){ 
                return dictionary.ContainsKey(item); 
            }
 
            bool ICollection.Remove(TKey item){
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_KeyCollectionSet);
                return false;
            } 

            IEnumerator IEnumerable.GetEnumerator() { 
                return new Enumerator(dictionary); 
            }
 
            IEnumerator IEnumerable.GetEnumerator() {
                return new Enumerator(dictionary);
            }
 
            void ICollection.CopyTo(Array array, int index) {
                if (array==null) { 
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.array); 
                }
 
                if (array.Rank != 1) {
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_RankMultiDimNotSupported);
                }
 
                if( array.GetLowerBound(0) != 0 ) {
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_NonZeroLowerBound); 
                } 

                if (index < 0 || index > array.Length) { 
                    ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.index, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
                }

                if (array.Length - index < dictionary.Count) { 
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_ArrayPlusOffTooSmall);
                } 
 
                TKey[] keys = array as TKey[];
                if (keys != null) { 
                    CopyTo(keys, index);
                }
                else {
                    object[] objects = array as object[]; 
                    if (objects == null) {
                        ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType); 
                    } 

                    int count = dictionary.count; 
                    Entry[] entries = dictionary.entries;
                    try {
                        for (int i = 0; i < count; i++) {
                            if (entries[i].hashCode >= 0) objects[index++] = entries[i].key; 
                        }
                    } 
                    catch(ArrayTypeMismatchException) { 
                        ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType);
                    } 
                }
            }

            bool ICollection.IsSynchronized { 
                get { return false; }
            } 
 
            Object ICollection.SyncRoot {
                get { return ((ICollection)dictionary).SyncRoot; } 
            }

            [Serializable]
            public struct Enumerator : IEnumerator, System.Collections.IEnumerator 
            {
                private Dictionary dictionary; 
                private int index; 
                private int version;
                private TKey currentKey; 

                internal Enumerator(Dictionary dictionary) {
                    this.dictionary = dictionary;
                    version = dictionary.version; 
                    index = 0;
                    currentKey = default(TKey); 
                } 

                public void Dispose() { 
                }

                public bool MoveNext() {
                    if (version != dictionary.version) { 
                        ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion);
                    } 
 
                    while ((uint)index < (uint)dictionary.count) {
                        if (dictionary.entries[index].hashCode >= 0) { 
                            currentKey = dictionary.entries[index].key;
                            index++;
                            return true;
                        } 
                        index++;
                    } 
 
                    index = dictionary.count + 1;
                    currentKey = default(TKey); 
                    return false;
                }

                public TKey Current { 
                    get {
                        return currentKey; 
                    } 
                }
 
                Object System.Collections.IEnumerator.Current {
                    get {
                        if( index == 0 || (index == dictionary.count + 1)) {
                             ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumOpCantHappen); 
                        }
 
                        return currentKey; 
                    }
                } 

                void System.Collections.IEnumerator.Reset() {
                    if (version != dictionary.version) {
                        ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion); 
                    }
 
                    index = 0; 
                    currentKey = default(TKey);
                } 
            }
        }

        [DebuggerTypeProxy(typeof(Mscorlib_DictionaryValueCollectionDebugView<,>))] 
        [DebuggerDisplay("Count = {Count}")]
        [Serializable] 
        public sealed class ValueCollection: ICollection, ICollection 
        {
            private Dictionary dictionary; 

            public ValueCollection(Dictionary dictionary) {
                if (dictionary == null) {
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.dictionary); 
                }
                this.dictionary = dictionary; 
            } 

            public Enumerator GetEnumerator() { 
                return new Enumerator(dictionary);
            }

            public void CopyTo(TValue[] array, int index) { 
                if (array == null) {
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.array); 
                } 

                if (index < 0 || index > array.Length) { 
                    ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.index, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
                }

                if (array.Length - index < dictionary.Count) { 
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_ArrayPlusOffTooSmall);
                } 
 
                int count = dictionary.count;
                Entry[] entries = dictionary.entries; 
                for (int i = 0; i < count; i++) {
                    if (entries[i].hashCode >= 0) array[index++] = entries[i].value;
                }
            } 

            public int Count { 
                get { return dictionary.Count; } 
            }
 
            bool ICollection.IsReadOnly {
                get { return true; }
            }
 
            void ICollection.Add(TValue item){
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ValueCollectionSet); 
            } 

            bool ICollection.Remove(TValue item){ 
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ValueCollectionSet);
                return false;
            }
 
            void ICollection.Clear(){
                ThrowHelper.ThrowNotSupportedException(ExceptionResource.NotSupported_ValueCollectionSet); 
            } 

            bool ICollection.Contains(TValue item){ 
                return dictionary.ContainsValue(item);
            }

            IEnumerator IEnumerable.GetEnumerator() { 
                return new Enumerator(dictionary);
            } 
 
            IEnumerator IEnumerable.GetEnumerator() {
                return new Enumerator(dictionary); 
            }

            void ICollection.CopyTo(Array array, int index) {
                if (array == null) { 
                    ThrowHelper.ThrowArgumentNullException(ExceptionArgument.array);
                } 
 
                if (array.Rank != 1) {
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_RankMultiDimNotSupported); 
                }

                if( array.GetLowerBound(0) != 0 ) {
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_NonZeroLowerBound); 
                }
 
                if (index < 0 || index > array.Length) { 
                    ThrowHelper.ThrowArgumentOutOfRangeException(ExceptionArgument.index, ExceptionResource.ArgumentOutOfRange_NeedNonNegNum);
                } 

                if (array.Length - index < dictionary.Count)
                    ThrowHelper.ThrowArgumentException(ExceptionResource.Arg_ArrayPlusOffTooSmall);
 
                TValue[] values = array as TValue[];
                if (values != null) { 
                    CopyTo(values, index); 
                }
                else { 
                    object[] objects = array as object[];
                    if (objects == null) {
                        ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType);
                    } 

                    int count = dictionary.count; 
                    Entry[] entries = dictionary.entries; 
                    try {
                        for (int i = 0; i < count; i++) { 
                            if (entries[i].hashCode >= 0) objects[index++] = entries[i].value;
                        }
                    }
                    catch(ArrayTypeMismatchException) { 
                        ThrowHelper.ThrowArgumentException(ExceptionResource.Argument_InvalidArrayType);
                    } 
                } 
            }
 
            bool ICollection.IsSynchronized {
                get { return false; }
            }
 
            Object ICollection.SyncRoot {
                get { return ((ICollection)dictionary).SyncRoot; } 
            } 

            [Serializable] 
            public struct Enumerator : IEnumerator, System.Collections.IEnumerator
            {
                private Dictionary dictionary;
                private int index; 
                private int version;
                private TValue currentValue; 
 
                internal Enumerator(Dictionary dictionary) {
                    this.dictionary = dictionary; 
                    version = dictionary.version;
                    index = 0;
                    currentValue = default(TValue);
                } 

                public void Dispose() { 
                } 

                public bool MoveNext() { 
                    if (version != dictionary.version) {
                        ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion);
                    }
 
                    while ((uint)index < (uint)dictionary.count) {
                        if (dictionary.entries[index].hashCode >= 0) { 
                            currentValue = dictionary.entries[index].value; 
                            index++;
                            return true; 
                        }
                        index++;
                    }
                    index = dictionary.count + 1; 
                    currentValue = default(TValue);
                    return false; 
                } 

                public TValue Current { 
                    get {
                        return currentValue;
                    }
                } 

                Object System.Collections.IEnumerator.Current { 
                    get { 
                        if( index == 0 || (index == dictionary.count + 1)) {
                             ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumOpCantHappen); 
                        }

                        return currentValue;
                    } 
                }
 
                void System.Collections.IEnumerator.Reset() { 
                    if (version != dictionary.version) {
                        ThrowHelper.ThrowInvalidOperationException(ExceptionResource.InvalidOperation_EnumFailedVersion); 
                    }
                    index = 0;
                    currentValue = default(TValue);
                } 
            }
        } 
    } 
}

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

                        

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