// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
#nullable disable
 
using System.Runtime.InteropServices;
using Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Interop;
using Microsoft.VisualStudio.LanguageServices.Implementation.Interop;
 
namespace Microsoft.VisualStudio.LanguageServices.Implementation.CodeModel.Collections;
 
[ComVisible(true)]
[ComDefaultInterface(typeof(ICodeElements))]
public sealed class EmptyCollection : AbstractCodeElementCollection
{
    private static readonly Snapshot s_snapshot = new CodeElementSnapshot([]);
 
    internal static EnvDTE.CodeElements Create(
        CodeModelState state,
        object parent)
    {
        var collection = new EmptyCollection(state, parent);
        return (EnvDTE.CodeElements)ComAggregate.CreateAggregatedObject(collection);
    }
 
    private EmptyCollection(
        CodeModelState state,
        object parent)
        : base(state, parent)
    {
    }
 
    internal override Snapshot CreateSnapshot()
        => s_snapshot;
 
    protected override bool TryGetItemByIndex(int index, out EnvDTE.CodeElement element)
    {
        element = null;
        return false;
    }
 
    protected override bool TryGetItemByName(string name, out EnvDTE.CodeElement element)
    {
        element = null;
        return false;
    }
 
    public override int Count
    {
        get { return 0; }
    }
}