Code:
/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / CompMod / System / Collections / Specialized / HybridDictionary.cs / 1305376 / HybridDictionary.cs
//------------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
//-----------------------------------------------------------------------------
namespace System.Collections.Specialized {
using System.Collections;
using System.Globalization;
///
///
/// This data structure implements IDictionary first using a linked list
/// (ListDictionary) and then switching over to use Hashtable when large. This is recommended
/// for cases where the number of elements in a dictionary is unknown and might be small.
///
/// It also has a single boolean parameter to allow case-sensitivity that is not affected by
/// ambient culture and has been optimized for looking up case-insensitive symbols
///
///
[Serializable]
public class HybridDictionary: IDictionary {
// These numbers have been carefully tested to be optimal. Please don't change them
// without doing thorough performance testing.
private const int CutoverPoint = 9;
private const int InitialHashtableSize = 13;
private const int FixedSizeCutoverPoint = 6;
// Instance variables. This keeps the HybridDictionary very light-weight when empty
private ListDictionary list;
private Hashtable hashtable;
private bool caseInsensitive;
///
/// [To be supplied.]
///
public HybridDictionary() {
}
///
/// [To be supplied.]
///
public HybridDictionary(int initialSize) : this(initialSize, false) {
}
///
/// [To be supplied.]
///
public HybridDictionary(bool caseInsensitive) {
this.caseInsensitive = caseInsensitive;
}
///
/// [To be supplied.]
///
public HybridDictionary(int initialSize, bool caseInsensitive) {
this.caseInsensitive = caseInsensitive;
if (initialSize >= FixedSizeCutoverPoint) {
if (caseInsensitive) {
hashtable = new Hashtable(initialSize, StringComparer.OrdinalIgnoreCase);
} else {
hashtable = new Hashtable(initialSize);
}
}
}
///
/// [To be supplied.]
///
public object this[object key] {
get {
//
// Hashtable supports multiple read, one writer thread safety.
// Although we never made the same guarantee for HybridDictionary,
// it is still nice to do the same thing here since we have recommended
// HybridDictioary as replacement for Hashtable.
//
//
ListDictionary cachedList = list;
if (hashtable != null) {
return hashtable[key];
} else if (cachedList != null) {
return cachedList[key];
} else {
//
// cachedList can be null in too cases:
// (1) The dictionary is empty, we will return null in this case
// (2) There is writer which is doing ChangeOver. However in that case
// we should see the change to hashtable as well.
// So it should work just fine.
//
//
if (key == null) {
throw new ArgumentNullException("key", SR.GetString(SR.ArgumentNull_Key));
}
return null;
}
}
set {
if (hashtable != null) {
hashtable[key] = value;
}
else if (list != null) {
if (list.Count >= CutoverPoint - 1) {
ChangeOver();
hashtable[key] = value;
} else {
list[key] = value;
}
}
else {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
list[key] = value;
}
}
}
private ListDictionary List {
get {
if (list == null) {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
}
return list;
}
}
private void ChangeOver() {
IDictionaryEnumerator en = list.GetEnumerator();
Hashtable newTable;
if (caseInsensitive) {
newTable = new Hashtable(InitialHashtableSize, StringComparer.OrdinalIgnoreCase);
} else {
newTable = new Hashtable(InitialHashtableSize);
}
while (en.MoveNext()) {
newTable.Add(en.Key, en.Value);
}
//
// Keep the order of writing to hashtable and list.
// We assume we will see the change in hashtable if list is set to null in
// this method in another reader thread.
//
hashtable = newTable;
list = null;
}
///
/// [To be supplied.]
///
public int Count {
get {
ListDictionary cachedList = list;
if (hashtable != null) {
return hashtable.Count;
} else if (cachedList != null) {
return cachedList.Count;
} else {
return 0;
}
}
}
///
/// [To be supplied.]
///
public ICollection Keys {
get {
if (hashtable != null) {
return hashtable.Keys;
} else {
return List.Keys;
}
}
}
///
/// [To be supplied.]
///
public bool IsReadOnly {
get {
return false;
}
}
///
/// [To be supplied.]
///
public bool IsFixedSize {
get {
return false;
}
}
///
/// [To be supplied.]
///
public bool IsSynchronized {
get {
return false;
}
}
///
/// [To be supplied.]
///
public object SyncRoot {
get {
return this;
}
}
///
/// [To be supplied.]
///
public ICollection Values {
get {
if (hashtable != null) {
return hashtable.Values;
} else {
return List.Values;
}
}
}
///
/// [To be supplied.]
///
public void Add(object key, object value) {
if (hashtable != null) {
hashtable.Add(key, value);
} else {
if (list == null) {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
list.Add(key, value);
}
else {
if (list.Count + 1 >= CutoverPoint) {
ChangeOver();
hashtable.Add(key, value);
} else {
list.Add(key, value);
}
}
}
}
///
/// [To be supplied.]
///
public void Clear() {
if(hashtable != null) {
Hashtable cachedHashtable = hashtable;
hashtable = null;
cachedHashtable.Clear();
}
if( list != null) {
ListDictionary cachedList = list;
list = null;
cachedList.Clear();
}
}
///
/// [To be supplied.]
///
public bool Contains(object key) {
ListDictionary cachedList = list;
if (hashtable != null) {
return hashtable.Contains(key);
} else if (cachedList != null) {
return cachedList.Contains(key);
} else {
if (key == null) {
throw new ArgumentNullException("key", SR.GetString(SR.ArgumentNull_Key));
}
return false;
}
}
///
/// [To be supplied.]
///
public void CopyTo(Array array, int index) {
if (hashtable != null) {
hashtable.CopyTo(array, index);
} else {
List.CopyTo(array, index);
}
}
///
/// [To be supplied.]
///
public IDictionaryEnumerator GetEnumerator() {
if (hashtable != null) {
return hashtable.GetEnumerator();
}
if (list == null) {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
}
return list.GetEnumerator();
}
///
/// [To be supplied.]
///
IEnumerator IEnumerable.GetEnumerator() {
if (hashtable != null) {
return hashtable.GetEnumerator();
}
if (list == null) {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
}
return list.GetEnumerator();
}
///
/// [To be supplied.]
///
public void Remove(object key) {
if (hashtable != null) {
hashtable.Remove(key);
}
else if (list != null){
list.Remove(key);
}
else {
if (key == null) {
throw new ArgumentNullException("key", SR.GetString(SR.ArgumentNull_Key));
}
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//------------------------------------------------------------------------------
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
//-----------------------------------------------------------------------------
namespace System.Collections.Specialized {
using System.Collections;
using System.Globalization;
///
///
/// This data structure implements IDictionary first using a linked list
/// (ListDictionary) and then switching over to use Hashtable when large. This is recommended
/// for cases where the number of elements in a dictionary is unknown and might be small.
///
/// It also has a single boolean parameter to allow case-sensitivity that is not affected by
/// ambient culture and has been optimized for looking up case-insensitive symbols
///
///
[Serializable]
public class HybridDictionary: IDictionary {
// These numbers have been carefully tested to be optimal. Please don't change them
// without doing thorough performance testing.
private const int CutoverPoint = 9;
private const int InitialHashtableSize = 13;
private const int FixedSizeCutoverPoint = 6;
// Instance variables. This keeps the HybridDictionary very light-weight when empty
private ListDictionary list;
private Hashtable hashtable;
private bool caseInsensitive;
///
/// [To be supplied.]
///
public HybridDictionary() {
}
///
/// [To be supplied.]
///
public HybridDictionary(int initialSize) : this(initialSize, false) {
}
///
/// [To be supplied.]
///
public HybridDictionary(bool caseInsensitive) {
this.caseInsensitive = caseInsensitive;
}
///
/// [To be supplied.]
///
public HybridDictionary(int initialSize, bool caseInsensitive) {
this.caseInsensitive = caseInsensitive;
if (initialSize >= FixedSizeCutoverPoint) {
if (caseInsensitive) {
hashtable = new Hashtable(initialSize, StringComparer.OrdinalIgnoreCase);
} else {
hashtable = new Hashtable(initialSize);
}
}
}
///
/// [To be supplied.]
///
public object this[object key] {
get {
//
// Hashtable supports multiple read, one writer thread safety.
// Although we never made the same guarantee for HybridDictionary,
// it is still nice to do the same thing here since we have recommended
// HybridDictioary as replacement for Hashtable.
//
//
ListDictionary cachedList = list;
if (hashtable != null) {
return hashtable[key];
} else if (cachedList != null) {
return cachedList[key];
} else {
//
// cachedList can be null in too cases:
// (1) The dictionary is empty, we will return null in this case
// (2) There is writer which is doing ChangeOver. However in that case
// we should see the change to hashtable as well.
// So it should work just fine.
//
//
if (key == null) {
throw new ArgumentNullException("key", SR.GetString(SR.ArgumentNull_Key));
}
return null;
}
}
set {
if (hashtable != null) {
hashtable[key] = value;
}
else if (list != null) {
if (list.Count >= CutoverPoint - 1) {
ChangeOver();
hashtable[key] = value;
} else {
list[key] = value;
}
}
else {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
list[key] = value;
}
}
}
private ListDictionary List {
get {
if (list == null) {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
}
return list;
}
}
private void ChangeOver() {
IDictionaryEnumerator en = list.GetEnumerator();
Hashtable newTable;
if (caseInsensitive) {
newTable = new Hashtable(InitialHashtableSize, StringComparer.OrdinalIgnoreCase);
} else {
newTable = new Hashtable(InitialHashtableSize);
}
while (en.MoveNext()) {
newTable.Add(en.Key, en.Value);
}
//
// Keep the order of writing to hashtable and list.
// We assume we will see the change in hashtable if list is set to null in
// this method in another reader thread.
//
hashtable = newTable;
list = null;
}
///
/// [To be supplied.]
///
public int Count {
get {
ListDictionary cachedList = list;
if (hashtable != null) {
return hashtable.Count;
} else if (cachedList != null) {
return cachedList.Count;
} else {
return 0;
}
}
}
///
/// [To be supplied.]
///
public ICollection Keys {
get {
if (hashtable != null) {
return hashtable.Keys;
} else {
return List.Keys;
}
}
}
///
/// [To be supplied.]
///
public bool IsReadOnly {
get {
return false;
}
}
///
/// [To be supplied.]
///
public bool IsFixedSize {
get {
return false;
}
}
///
/// [To be supplied.]
///
public bool IsSynchronized {
get {
return false;
}
}
///
/// [To be supplied.]
///
public object SyncRoot {
get {
return this;
}
}
///
/// [To be supplied.]
///
public ICollection Values {
get {
if (hashtable != null) {
return hashtable.Values;
} else {
return List.Values;
}
}
}
///
/// [To be supplied.]
///
public void Add(object key, object value) {
if (hashtable != null) {
hashtable.Add(key, value);
} else {
if (list == null) {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
list.Add(key, value);
}
else {
if (list.Count + 1 >= CutoverPoint) {
ChangeOver();
hashtable.Add(key, value);
} else {
list.Add(key, value);
}
}
}
}
///
/// [To be supplied.]
///
public void Clear() {
if(hashtable != null) {
Hashtable cachedHashtable = hashtable;
hashtable = null;
cachedHashtable.Clear();
}
if( list != null) {
ListDictionary cachedList = list;
list = null;
cachedList.Clear();
}
}
///
/// [To be supplied.]
///
public bool Contains(object key) {
ListDictionary cachedList = list;
if (hashtable != null) {
return hashtable.Contains(key);
} else if (cachedList != null) {
return cachedList.Contains(key);
} else {
if (key == null) {
throw new ArgumentNullException("key", SR.GetString(SR.ArgumentNull_Key));
}
return false;
}
}
///
/// [To be supplied.]
///
public void CopyTo(Array array, int index) {
if (hashtable != null) {
hashtable.CopyTo(array, index);
} else {
List.CopyTo(array, index);
}
}
///
/// [To be supplied.]
///
public IDictionaryEnumerator GetEnumerator() {
if (hashtable != null) {
return hashtable.GetEnumerator();
}
if (list == null) {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
}
return list.GetEnumerator();
}
///
/// [To be supplied.]
///
IEnumerator IEnumerable.GetEnumerator() {
if (hashtable != null) {
return hashtable.GetEnumerator();
}
if (list == null) {
list = new ListDictionary(caseInsensitive ? StringComparer.OrdinalIgnoreCase : null);
}
return list.GetEnumerator();
}
///
/// [To be supplied.]
///
public void Remove(object key) {
if (hashtable != null) {
hashtable.Remove(key);
}
else if (list != null){
list.Remove(key);
}
else {
if (key == null) {
throw new ArgumentNullException("key", SR.GetString(SR.ArgumentNull_Key));
}
}
}
}
}
// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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