// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

namespace System.Collections
{
    // Base interface for all enumerators, providing a simple approach
    // to iterating over a collection.
    public interface IEnumerator
    {
        // Advances the enumerator to the next element of the enumeration and
        // returns a boolean indicating whether an element is available. Upon
        // creation, an enumerator is conceptually positioned before the first
        // element of the enumeration, and the first call to MoveNext
        // brings the first element of the enumeration into view.
        //
        bool MoveNext();

        // Returns the current element of the enumeration. The returned value is
        // undefined before the first call to MoveNext and following a
        // call to MoveNext that returned false. Multiple calls to
        // GetCurrent with no intervening calls to MoveNext
        // will return the same object.
        //

#nullable disable // explicitly leaving Current as "oblivious" to avoid spurious warnings in foreach over non-generic enumerables
        object Current
#nullable restore
        {
            get;
        }

        // Resets the enumerator to the beginning of the enumeration, starting over.
        // The preferred behavior for Reset is to return the exact same enumeration.
        // This means if you modify the underlying collection then call Reset, your
        // IEnumerator will be invalid, just as it would have been if you had called
        // MoveNext or Current.
        //
        void Reset();
    }
}