/
SyntaxTokenList.Reversed.cs
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/
SyntaxTokenList.Reversed.cs
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// 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 enable
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
using System.Runtime.InteropServices;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis
{
public partial struct SyntaxTokenList
{
/// <summary>
/// Reversed enumerable.
/// </summary>
public readonly struct Reversed : IEnumerable<SyntaxToken>, IEquatable<Reversed>
{
private readonly SyntaxTokenList _list;
public Reversed(SyntaxTokenList list)
{
_list = list;
}
public Enumerator GetEnumerator()
{
return new Enumerator(in _list);
}
IEnumerator<SyntaxToken> IEnumerable<SyntaxToken>.GetEnumerator()
{
if (_list.Count == 0)
{
return SpecializedCollections.EmptyEnumerator<SyntaxToken>();
}
return new EnumeratorImpl(in _list);
}
IEnumerator IEnumerable.GetEnumerator()
{
if (_list.Count == 0)
{
return SpecializedCollections.EmptyEnumerator<SyntaxToken>();
}
return new EnumeratorImpl(in _list);
}
public override bool Equals(object? obj)
{
return obj is Reversed r && Equals(r);
}
public bool Equals(Reversed other)
{
return _list.Equals(other._list);
}
public override int GetHashCode()
{
return _list.GetHashCode();
}
[SuppressMessage("Performance", "CA1067", Justification = "Equality not actually implemented")]
[StructLayout(LayoutKind.Auto)]
public struct Enumerator
{
private readonly SyntaxNode? _parent;
private readonly GreenNode? _singleNodeOrList;
private readonly int _baseIndex;
private readonly int _count;
private int _index;
private GreenNode? _current;
private int _position;
internal Enumerator(in SyntaxTokenList list)
: this()
{
if (list.Any())
{
_parent = list._parent;
_singleNodeOrList = list.Node;
_baseIndex = list._index;
_count = list.Count;
_index = _count;
_current = null;
var last = list.Last();
_position = last.Position + last.FullWidth;
}
}
public bool MoveNext()
{
if (_count == 0 || _index <= 0)
{
_current = null;
return false;
}
_index--;
Debug.Assert(_singleNodeOrList is object);
_current = GetGreenNodeAt(_singleNodeOrList, _index);
Debug.Assert(_current is object);
_position -= _current.FullWidth;
return true;
}
public SyntaxToken Current
{
get
{
if (_current == null)
{
throw new InvalidOperationException();
}
return new SyntaxToken(_parent, _current, _position, _baseIndex + _index);
}
}
public override bool Equals(object? obj)
{
throw new NotSupportedException();
}
public override int GetHashCode()
{
throw new NotSupportedException();
}
}
private class EnumeratorImpl : IEnumerator<SyntaxToken>
{
private Enumerator _enumerator;
// SyntaxTriviaList is a relatively big struct so is passed as ref
internal EnumeratorImpl(in SyntaxTokenList list)
{
_enumerator = new Enumerator(in list);
}
public SyntaxToken Current => _enumerator.Current;
object IEnumerator.Current => _enumerator.Current;
public bool MoveNext()
{
return _enumerator.MoveNext();
}
public void Reset()
{
throw new NotSupportedException();
}
public void Dispose()
{
}
}
}
}
}