// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System;
using System.Collections;
using System.Collections.Generic;
 
namespace Microsoft.AspNetCore.Razor.Language.Syntax;
 
internal readonly partial struct SyntaxList<TNode>
    where TNode : SyntaxNode
{
    public struct Enumerator
    {
        private readonly SyntaxList<TNode> _list;
        private int _index;
 
        internal Enumerator(in SyntaxList<TNode> list)
        {
            _list = list;
            _index = -1;
        }
 
        public bool MoveNext()
        {
            var newIndex = _index + 1;
            if (newIndex < _list.Count)
            {
                _index = newIndex;
                return true;
            }
 
            return false;
        }
 
        public readonly TNode Current
            => (TNode)_list.ItemInternal(_index)!;
 
        public void Reset()
        {
            _index = -1;
        }
 
        public override readonly bool Equals(object? obj)
            => throw new NotSupportedException();
 
        public override readonly int GetHashCode()
            => throw new NotSupportedException();
    }
 
    private sealed class EnumeratorImpl : IEnumerator<TNode>
    {
        private Enumerator _enumerator;
 
        internal EnumeratorImpl(in SyntaxList<TNode> list)
        {
            _enumerator = new Enumerator(in list);
        }
 
        public bool MoveNext()
            => _enumerator.MoveNext();
 
        public TNode Current
            => _enumerator.Current;
 
        void IDisposable.Dispose()
        {
        }
 
        object IEnumerator.Current
            => _enumerator.Current;
 
        void IEnumerator.Reset()
            => _enumerator.Reset();
    }
}