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AspClassic.Scripting/Utils/CheckedDictionaryEnumerator.cs

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+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace AspClassic.Scripting.Utils;
+
+internal abstract class CheckedDictionaryEnumerator : IDictionaryEnumerator, IEnumerator<KeyValuePair<object, object>>, IDisposable, IEnumerator
+{
+	private enum EnumeratorState
+	{
+		NotStarted,
+		Started,
+		Ended
+	}
+
+	private EnumeratorState _enumeratorState;
+
+	public DictionaryEntry Entry
+	{
+		get
+		{
+			CheckEnumeratorState();
+			return new DictionaryEntry(Key, Value);
+		}
+	}
+
+	public object Key
+	{
+		get
+		{
+			CheckEnumeratorState();
+			return GetKey();
+		}
+	}
+
+	public object Value
+	{
+		get
+		{
+			CheckEnumeratorState();
+			return GetValue();
+		}
+	}
+
+	public object Current => Entry;
+
+	KeyValuePair<object, object> IEnumerator<KeyValuePair<object, object>>.Current => new KeyValuePair<object, object>(Key, Value);
+
+	private void CheckEnumeratorState()
+	{
+		if (_enumeratorState == EnumeratorState.NotStarted)
+		{
+			throw Error.EnumerationNotStarted();
+		}
+		if (_enumeratorState == EnumeratorState.Ended)
+		{
+			throw Error.EnumerationFinished();
+		}
+	}
+
+	public bool MoveNext()
+	{
+		if (_enumeratorState == EnumeratorState.Ended)
+		{
+			throw Error.EnumerationFinished();
+		}
+		bool flag = DoMoveNext();
+		if (flag)
+		{
+			_enumeratorState = EnumeratorState.Started;
+		}
+		else
+		{
+			_enumeratorState = EnumeratorState.Ended;
+		}
+		return flag;
+	}
+
+	public void Reset()
+	{
+		DoReset();
+		_enumeratorState = EnumeratorState.NotStarted;
+	}
+
+	public void Dispose()
+	{
+		GC.SuppressFinalize(this);
+	}
+
+	protected abstract object GetKey();
+
+	protected abstract object GetValue();
+
+	protected abstract bool DoMoveNext();
+
+	protected abstract void DoReset();
+}