/
SyntaxTriviaList.Reversed.cs
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/
SyntaxTriviaList.Reversed.cs
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// Copyright (c) Microsoft. All Rights Reserved. Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.InteropServices;
using Roslyn.Utilities;
namespace Microsoft.CodeAnalysis
{
public partial struct SyntaxTriviaList
{
/// <summary>
/// Reversed enumerable.
/// </summary>
public readonly struct Reversed : IEnumerable<SyntaxTrivia>, IEquatable<Reversed>
{
private readonly SyntaxTriviaList _list;
public Reversed(SyntaxTriviaList list)
{
_list = list;
}
public Enumerator GetEnumerator()
{
return new Enumerator(in _list);
}
IEnumerator<SyntaxTrivia> IEnumerable<SyntaxTrivia>.GetEnumerator()
{
if (_list.Count == 0)
{
return SpecializedCollections.EmptyEnumerator<SyntaxTrivia>();
}
return new ReversedEnumeratorImpl(in _list);
}
IEnumerator
IEnumerable.GetEnumerator()
{
if (_list.Count == 0)
{
return SpecializedCollections.EmptyEnumerator<SyntaxTrivia>();
}
return new ReversedEnumeratorImpl(in _list);
}
public override int GetHashCode()
{
return _list.GetHashCode();
}
public override bool Equals(object obj)
{
return obj is Reversed && Equals((Reversed)obj);
}
public bool Equals(Reversed other)
{
return _list.Equals(other._list);
}
[StructLayout(LayoutKind.Auto)]
public struct Enumerator
{
private readonly SyntaxToken _token;
private readonly GreenNode _singleNodeOrList;
private readonly int _baseIndex;
private readonly int _count;
private int _index;
private GreenNode _current;
private int _position;
internal Enumerator(in SyntaxTriviaList list)
: this()
{
if (list.Any())
{
_token = list.Token;
_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--;
_current = GetGreenNodeAt(_singleNodeOrList, _index);
_position -= _current.FullWidth;
return true;
}
public SyntaxTrivia Current
{
get
{
if (_current == null)
{
throw new InvalidOperationException();
}
return new SyntaxTrivia(_token, _current, _position, _baseIndex + _index);
}
}
}
private class ReversedEnumeratorImpl : IEnumerator<SyntaxTrivia>
{
private Enumerator _enumerator;
// SyntaxTriviaList is a relatively big struct so is passed as ref
internal ReversedEnumeratorImpl(in SyntaxTriviaList list)
{
_enumerator = new Enumerator(in list);
}
public SyntaxTrivia Current => _enumerator.Current;
object IEnumerator.Current => _enumerator.Current;
public bool MoveNext()
{
return _enumerator.MoveNext();
}
public void Reset()
{
throw new NotSupportedException();
}
public void Dispose()
{
}
}
}
}
}