/* ****************************************************************************
*
* 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.
*
*
* ***************************************************************************/
#if !CLR2
using System.Linq.Expressions;
#else
using Microsoft.Scripting.Ast;
#endif
using System;
using System.Collections;
using System.Collections.Generic;
namespace Microsoft.Scripting.Utils{
/// <summary>
/// Not all .NET enumerators throw exceptions if accessed in an invalid state. This type
/// can be used to throw exceptions from enumerators implemented in IronPython.
/// </summary>
abstract class CheckedDictionaryEnumerator : IDictionaryEnumerator, IEnumerator<KeyValuePair<object, object>> {
private EnumeratorState _enumeratorState = EnumeratorState.NotStarted;
private void CheckEnumeratorState() {
if (_enumeratorState == EnumeratorState.NotStarted)
throw Error.EnumerationNotStarted();
else if (_enumeratorState == EnumeratorState.Ended)
throw Error.EnumerationFinished();
}
#region IDictionaryEnumerator Members
public DictionaryEntry Entry {
get {
CheckEnumeratorState();
return new DictionaryEntry(Key, Value);
}
}
public object Key {
get {
CheckEnumeratorState();
return GetKey();
}
}
public object Value {
get {
CheckEnumeratorState();
return GetValue();
}
}
#endregion
#region IEnumerator Members
public bool MoveNext() {
if (_enumeratorState == EnumeratorState.Ended)
throw Error.EnumerationFinished();
bool result = DoMoveNext();
if (result)
_enumeratorState = EnumeratorState.Started;
else
_enumeratorState = EnumeratorState.Ended;
return result;
}
public object Current { get { return Entry; } }
public void Reset() {
DoReset();
_enumeratorState = EnumeratorState.NotStarted;
}
#endregion
#region IEnumerator<KeyValuePair<object,object>> Members
KeyValuePair<object, object> IEnumerator<KeyValuePair<object, object>>.Current {
get { return new KeyValuePair<object, object>(Key, Value); }
}
#endregion
#region IDisposable Members
public void Dispose() {
GC.SuppressFinalize(this);
}
#endregion
#region Methods that a sub-type needs to implement
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1024:UsePropertiesWhereAppropriate")] // TODO: fix
protected abstract object GetKey();
[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Design", "CA1024:UsePropertiesWhereAppropriate")] // TODO: fix
protected abstract object GetValue();
protected abstract bool DoMoveNext();
protected abstract void DoReset();
#endregion
private enum EnumeratorState {
NotStarted,
Started,
Ended
}
}
}
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