IOrderedDictionary.GetEnumerator Méthode
Définition
Important
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Retourne un énumérateur qui itère au sein de la collection IOrderedDictionary.
public:
System::Collections::IDictionaryEnumerator ^ GetEnumerator();public System.Collections.IDictionaryEnumerator GetEnumerator ();abstract member GetEnumerator : unit -> System.Collections.IDictionaryEnumeratorPublic Function GetEnumerator () As IDictionaryEnumeratorRetours
IDictionaryEnumerator pour l’intégralité de la collection IOrderedDictionary.
Implémente
Exemples
L’exemple de code suivant illustre l’implémentation d’une IOrderedDictionary simple basée sur la ArrayList classe. L’implémentation IOrderedDictionary stocke les prénoms en tant que clés et noms comme valeurs, avec l’exigence ajoutée que chaque prénom est unique. Ce code fait partie d’un exemple de code plus volumineux fourni pour la IOrderedDictionary classe.
public ref class PeopleEnum : IDictionaryEnumerator
{
private:
// Enumerators are positioned before the first element
// until the first MoveNext() call.
int position;
ArrayList^ _people;
public:
PeopleEnum(ArrayList^ list)
{
this->Reset();
_people = list;
}
virtual bool MoveNext()
{
position++;
return (position < _people->Count);
}
virtual void Reset()
{
position = -1;
}
virtual property Object^ Current
{
Object^ get()
{
try
{
return _people[position];
}
catch (IndexOutOfRangeException^)
{
throw gcnew InvalidOperationException();
}
}
}
virtual property DictionaryEntry Entry
{
DictionaryEntry get()
{
return (DictionaryEntry)(Current);
}
}
virtual property Object^ Key
{
Object^ get()
{
try
{
return ((DictionaryEntry^)_people[position])->Key;
}
catch (IndexOutOfRangeException^)
{
throw gcnew InvalidOperationException();
}
}
}
virtual property Object^ Value
{
Object^ get()
{
try
{
return ((DictionaryEntry^)_people[position])->Value;
}
catch (IndexOutOfRangeException^)
{
throw gcnew InvalidOperationException();
}
}
}
};
public ref class People : IOrderedDictionary
{
private:
ArrayList^ _people;
public:
People(int numItems)
{
_people = gcnew ArrayList(numItems);
}
int IndexOfKey(Object^ key)
{
for (int i = 0; i < _people->Count; i++)
{
if (((DictionaryEntry^)_people[i])->Key == key)
return i;
}
// key not found, return -1.
return -1;
}
virtual property Object^ default[Object^]
{
Object^ get(Object^ key)
{
return ((DictionaryEntry^)_people[IndexOfKey(key)])->Value;
}
void set(Object^ key, Object^ value)
{
_people[IndexOfKey(key)] = gcnew DictionaryEntry(key, value);
}
}
// IOrderedDictionary Members
virtual IDictionaryEnumerator^ GetEnumerator()
{
return gcnew PeopleEnum(_people);
}
virtual void Insert(int index, Object^ key, Object^ value)
{
if (IndexOfKey(key) != -1)
{
throw gcnew ArgumentException("An element with the same key already exists in the collection.");
}
_people->Insert(index, gcnew DictionaryEntry(key, value));
}
virtual void RemoveAt(int index)
{
_people->RemoveAt(index);
}
virtual property Object^ default[int]
{
Object^ get(int index)
{
return ((DictionaryEntry^)_people[index])->Value;
}
void set(int index, Object^ value)
{
Object^ key = ((DictionaryEntry^)_people[index])->Key;
_people[index] = gcnew DictionaryEntry(key, value);
}
}
// IDictionary Members
virtual void Add(Object^ key, Object^ value)
{
if (IndexOfKey(key) != -1)
{
throw gcnew ArgumentException("An element with the same key already exists in the collection.");
}
_people->Add(gcnew DictionaryEntry(key, value));
}
virtual void Clear()
{
_people->Clear();
}
virtual bool Contains(Object^ key)
{
if (IndexOfKey(key) == -1)
{
return false;
}
else
{
return true;
}
}
virtual property bool IsFixedSize
{
bool get()
{
return false;
}
}
virtual property bool IsReadOnly
{
bool get()
{
return false;
}
}
virtual property ICollection^ Keys
{
ICollection^ get()
{
ArrayList^ KeyCollection = gcnew ArrayList(_people->Count);
for (int i = 0; i < _people->Count; i++)
{
KeyCollection->Add( ((DictionaryEntry^)_people[i])->Key );
}
return KeyCollection;
}
}
virtual void Remove(Object^ key)
{
_people->RemoveAt(IndexOfKey(key));
}
virtual property ICollection^ Values
{
ICollection ^get()
{
ArrayList^ ValueCollection = gcnew ArrayList(_people->Count);
for (int i = 0; i < _people->Count; i++)
{
ValueCollection->Add( ((DictionaryEntry^)_people[i])->Value );
}
return ValueCollection;
}
}
// ICollection Members
virtual void CopyTo(Array^ array, int index)
{
_people->CopyTo(array, index);
}
virtual property int Count
{
int get()
{
return _people->Count;
}
}
virtual property bool IsSynchronized
{
bool get()
{
return _people->IsSynchronized;
}
}
virtual property Object^ SyncRoot
{
Object^ get()
{
return _people->SyncRoot;
}
}
// IEnumerable Members
virtual IEnumerator^ IfcGetEnumerator() = IEnumerable::GetEnumerator
{
return (IEnumerator^) gcnew PeopleEnum(_people);
}
};
public class People : IOrderedDictionary
{
private ArrayList _people;
public People(int numItems)
{
_people = new ArrayList(numItems);
}
public int IndexOfKey(object key)
{
for (int i = 0; i < _people.Count; i++)
{
if (((DictionaryEntry)_people[i]).Key == key)
return i;
}
// key not found, return -1.
return -1;
}
public object this[object key]
{
get
{
return ((DictionaryEntry)_people[IndexOfKey(key)]).Value;
}
set
{
_people[IndexOfKey(key)] = new DictionaryEntry(key, value);
}
}
// IOrderedDictionary Members
public IDictionaryEnumerator GetEnumerator()
{
return new PeopleEnum(_people);
}
public void Insert(int index, object key, object value)
{
if (IndexOfKey(key) != -1)
{
throw new ArgumentException("An element with the same key already exists in the collection.");
}
_people.Insert(index, new DictionaryEntry(key, value));
}
public void RemoveAt(int index)
{
_people.RemoveAt(index);
}
public object this[int index]
{
get
{
return ((DictionaryEntry)_people[index]).Value;
}
set
{
object key = ((DictionaryEntry)_people[index]).Key;
_people[index] = new DictionaryEntry(key, value);
}
}
// IDictionary Members
public void Add(object key, object value)
{
if (IndexOfKey(key) != -1)
{
throw new ArgumentException("An element with the same key already exists in the collection.");
}
_people.Add(new DictionaryEntry(key, value));
}
public void Clear()
{
_people.Clear();
}
public bool Contains(object key)
{
if (IndexOfKey(key) == -1)
{
return false;
}
else
{
return true;
}
}
public bool IsFixedSize
{
get
{
return false;
}
}
public bool IsReadOnly
{
get
{
return false;
}
}
public ICollection Keys
{
get
{
ArrayList KeyCollection = new ArrayList(_people.Count);
for (int i = 0; i < _people.Count; i++)
{
KeyCollection.Add( ((DictionaryEntry)_people[i]).Key );
}
return KeyCollection;
}
}
public void Remove(object key)
{
_people.RemoveAt(IndexOfKey(key));
}
public ICollection Values
{
get
{
ArrayList ValueCollection = new ArrayList(_people.Count);
for (int i = 0; i < _people.Count; i++)
{
ValueCollection.Add( ((DictionaryEntry)_people[i]).Value );
}
return ValueCollection;
}
}
// ICollection Members
public void CopyTo(Array array, int index)
{
_people.CopyTo(array, index);
}
public int Count
{
get
{
return _people.Count;
}
}
public bool IsSynchronized
{
get
{
return _people.IsSynchronized;
}
}
public object SyncRoot
{
get
{
return _people.SyncRoot;
}
}
// IEnumerable Members
IEnumerator IEnumerable.GetEnumerator()
{
return new PeopleEnum(_people);
}
}
public class PeopleEnum : IDictionaryEnumerator
{
public ArrayList _people;
// Enumerators are positioned before the first element
// until the first MoveNext() call.
int position = -1;
public PeopleEnum(ArrayList list)
{
_people = list;
}
public bool MoveNext()
{
position++;
return (position < _people.Count);
}
public void Reset()
{
position = -1;
}
public object Current
{
get
{
try
{
return _people[position];
}
catch (IndexOutOfRangeException)
{
throw new InvalidOperationException();
}
}
}
public DictionaryEntry Entry
{
get
{
return (DictionaryEntry)Current;
}
}
public object Key
{
get
{
try
{
return ((DictionaryEntry)_people[position]).Key;
}
catch (IndexOutOfRangeException)
{
throw new InvalidOperationException();
}
}
}
public object Value
{
get
{
try
{
return ((DictionaryEntry)_people[position]).Value;
}
catch (IndexOutOfRangeException)
{
throw new InvalidOperationException();
}
}
}
}
Public Class People
Implements IOrderedDictionary
Private _people As ArrayList
Public Sub New(ByVal numItems As Integer)
_people = New ArrayList(numItems)
End Sub
Public Function IndexOfKey(ByVal key As Object) As Integer
Dim i As Integer
For i = 0 To _people.Count - 1
If CType(_people(i), DictionaryEntry).Key = key Then
Return i
End If
Next i
' key not found, return -1.
Return -1
End Function
' IOrderedDictionary Members
Public Function GetEnumerator() As IDictionaryEnumerator _
Implements IOrderedDictionary.GetEnumerator
Return New PeopleEnum(_people)
End Function
Public Sub Insert(ByVal index As Integer, ByVal key As Object, _
ByVal value As Object) Implements IOrderedDictionary.Insert
If Not IndexOfKey(key) = -1 Then
Throw New ArgumentException("An element with the same key already exists in the collection.")
End If
_people.Insert(index, New DictionaryEntry(key, value))
End Sub
Public Sub RemoveAt(ByVal index As Integer) _
Implements IOrderedDictionary.RemoveAt
_people.RemoveAt(index)
End Sub
Public Property Item(ByVal index As Integer) As Object _
Implements IOrderedDictionary.Item
Get
Return CType(_people(index), DictionaryEntry).Value
End Get
Set(ByVal value As Object)
Dim key As Object = CType(_people(index), DictionaryEntry).Key
_people(index) = New DictionaryEntry(key, value)
End Set
End Property
' IDictionary Members
Public Function IDictionaryGetEnumerator() As IDictionaryEnumerator _
Implements IDictionary.GetEnumerator
Return New PeopleEnum(_people)
End Function
Public Property Item(ByVal key As Object) As Object _
Implements IDictionary.Item
Get
Return CType(_people(IndexOfKey(key)), DictionaryEntry).Value
End Get
Set(ByVal value)
_people(IndexOfKey(key)) = New DictionaryEntry(key, value)
End Set
End Property
Public Sub Add(ByVal key As Object, ByVal value As Object) _
Implements IDictionary.Add
If Not IndexOfKey(key) = -1 Then
Throw New ArgumentException("An element with the same key already exists in the collection.")
End If
_people.Add(New DictionaryEntry(key, value))
End Sub
Public Sub Clear() Implements IDictionary.Clear
_people.Clear()
End Sub
Public Function Contains(ByVal key As Object) As Boolean _
Implements IDictionary.Contains
If IndexOfKey(key) = -1 Then
Return False
Else
Return True
End If
End Function
Public ReadOnly Property IsFixedSize() As Boolean _
Implements IDictionary.IsFixedSize
Get
Return False
End Get
End Property
Public ReadOnly Property IsReadOnly() As Boolean _
Implements IDictionary.IsReadOnly
Get
Return False
End Get
End Property
Public ReadOnly Property Keys() As ICollection _
Implements IDictionary.Keys
Get
Dim KeyCollection As ArrayList = New ArrayList(_people.Count)
Dim i As Integer
For i = 0 To _people.Count - 1
KeyCollection.Add( CType(_people(i), DictionaryEntry).Key )
Next i
Return KeyCollection
End Get
End Property
Public Sub Remove(ByVal key As Object) _
Implements IDictionary.Remove
_people.RemoveAt(IndexOfKey(key))
End Sub
Public ReadOnly Property Values() As ICollection _
Implements IDictionary.Values
Get
Dim ValueCollection As ArrayList = New ArrayList(_people.Count)
Dim i As Integer
For i = 0 To _people.Count - 1
ValueCollection.Add( CType(_people(i), DictionaryEntry).Value )
Next i
Return ValueCollection
End Get
End Property
' ICollection Members
Public Sub CopyTo(ByVal array As Array, ByVal index As Integer) _
Implements ICollection.CopyTo
_people.CopyTo(Array, index)
End Sub
Public ReadOnly Property Count() As Integer _
Implements ICollection.Count
Get
Return _people.Count
End Get
End Property
Public ReadOnly Property IsSynchronized() As Boolean _
Implements ICollection.IsSynchronized
Get
Return _people.IsSynchronized
End Get
End Property
Public ReadOnly Property SyncRoot() As Object _
Implements ICollection.SyncRoot
Get
Return _people.SyncRoot
End Get
End Property
' IEnumerable Members
Public Function IEnumerableGetEnumerator() As IEnumerator _
Implements IEnumerable.GetEnumerator
Return New PeopleEnum(_people)
End Function
End Class
Public Class PeopleEnum
Implements IDictionaryEnumerator
Public _people As ArrayList
' Enumerators are positioned before the first element
' until the first MoveNext() call.
Dim position As Integer = -1
Public Sub New(ByVal list As ArrayList)
_people = list
End Sub
Public Function MoveNext() As Boolean _
Implements IEnumerator.MoveNext
position = position + 1
Return (position < _people.Count)
End Function
Public Sub Reset() _
Implements IEnumerator.Reset
position = -1
End Sub
Public ReadOnly Property Current() As Object _
Implements IEnumerator.Current
Get
Try
Return _people(position)
Catch e As IndexOutOfRangeException
Throw New InvalidOperationException()
End Try
End Get
End Property
Public ReadOnly Property Entry() As DictionaryEntry _
Implements IDictionaryEnumerator.Entry
Get
Return CType(Current, DictionaryEntry)
End Get
End Property
Public ReadOnly Property Key() As Object _
Implements IDictionaryEnumerator.Key
Get
Try
Return CType(_people(position), DictionaryEntry).Key
Catch e As IndexOutOfRangeException
Throw New InvalidOperationException()
End Try
End Get
End Property
Public ReadOnly Property Value() As Object _
Implements IDictionaryEnumerator.Value
Get
Try
Return CType(_people(position), DictionaryEntry).Value
Catch e As IndexOutOfRangeException
Throw New InvalidOperationException()
End Try
End Get
End Property
End Class
Remarques
L'instruction foreach du langage C# (for each en Visual Basic) se charge de la complexité des énumérateurs. Par conséquent, l’utilisation foreach est recommandée au lieu de manipuler directement l’énumérateur.
Les énumérateurs peuvent être utilisés pour lire les données de la collection, mais ils ne permettent pas de modifier la collection sous-jacente.
Au départ, l'énumérateur est positionné avant le premier élément de la collection. Reset replace également l'énumérateur à cette position. À cette position, la Current propriété n’est pas définie. Par conséquent, vous devez appeler MoveNext pour avancer l'énumérateur jusqu'au premier élément de la collection avant de lire la valeur de Current.
Current retourne le même objet tant que MoveNext ou Reset n'est pas appelé. MoveNext affecte l'élément suivant à Current.
Si MoveNext elle passe la fin de la collection, l’énumérateur est positionné après le dernier élément de la collection et MoveNext retourne false. Lorsque l’énumérateur se trouve à cette position, les appels suivants retournent MoveNext falseégalement . Si le dernier appel à MoveNext retourner false, Current n’est pas défini. Pour attribuer une nouvelle fois Current au premier élément de la collection, vous pouvez appeler Reset suivi de MoveNext.
Un énumérateur reste valide aussi longtemps que la collection demeure inchangée. Si des modifications sont apportées à la collection, telles que l’ajout, la modification ou la suppression d’éléments, l’énumérateur est définitivement invalidé et son comportement n’est pas défini.
Comme l’énumérateur ne dispose pas d’un accès exclusif à la collection, l’énumération d’une collection n’est pas intrinsèquement une procédure thread-safe. Pour garantir la sécurité des threads pendant l'énumération, vous pouvez verrouiller la collection tout au long de cette opération. Pour permettre à plusieurs threads d’accéder en lecture et en écriture à la collection, vous devez implémenter votre propre synchronisation.