120 lines
4.1 KiB
C#
120 lines
4.1 KiB
C#
// Copyright (c) Wojciech Figat. All rights reserved.
|
|
|
|
using System;
|
|
using System.Collections.Generic;
|
|
|
|
namespace Flax.Build
|
|
{
|
|
/// <summary>
|
|
/// The two-way enumerator interface that can move forward or backwards.
|
|
/// </summary>
|
|
/// <typeparam name="T">The element type.</typeparam>
|
|
/// <seealso cref="System.Collections.Generic.IEnumerator{T}" />
|
|
public interface ITwoWayEnumerator<T> : IEnumerator<T>
|
|
{
|
|
/// <summary>
|
|
/// Advances the enumerator to the previous element of the collection.
|
|
/// </summary>
|
|
/// <returns>
|
|
/// <see langword="true" /> if the enumerator was successfully advanced to the previous element; <see langword="false" /> if the enumerator has passed the beginning of the collection.</returns>
|
|
/// <exception cref="T:System.InvalidOperationException">The collection was modified after the enumerator was created. </exception>
|
|
bool MovePrevious();
|
|
}
|
|
|
|
/// <summary>
|
|
/// The implementation of the <see cref="ITwoWayEnumerator{T}"/> that uses a list.
|
|
/// </summary>
|
|
/// <typeparam name="T">The element type.</typeparam>
|
|
/// <seealso cref="Flax.Build.ITwoWayEnumerator{T}" />
|
|
public class TwoWayEnumerator<T> : ITwoWayEnumerator<T>
|
|
{
|
|
private IEnumerator<T> _enumerator;
|
|
private List<T> _buffer;
|
|
private int _index;
|
|
|
|
/// <summary>
|
|
/// Initializes a new instance of the <see cref="TwoWayEnumerator{T}"/> class.
|
|
/// </summary>
|
|
/// <param name="enumerator">The enumerator.</param>
|
|
public TwoWayEnumerator(IEnumerator<T> enumerator)
|
|
{
|
|
_enumerator = enumerator ?? throw new ArgumentNullException("enumerator");
|
|
_buffer = new List<T>();
|
|
_index = -1;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Advances the enumerator to the previous element of the collection.
|
|
/// </summary>
|
|
/// <returns><see langword="true" /> if the enumerator was successfully advanced to the previous element; <see langword="false" /> if the enumerator has passed the beginning of the collection.</returns>
|
|
public bool MovePrevious()
|
|
{
|
|
if (_index <= 0)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
--_index;
|
|
return true;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Advances the enumerator to the next element of the collection.
|
|
/// </summary>
|
|
/// <returns><see langword="true" /> if the enumerator was successfully advanced to the next element; <see langword="false" /> if the enumerator has passed the end of the collection.</returns>
|
|
public bool MoveNext()
|
|
{
|
|
if (_index < _buffer.Count - 1)
|
|
{
|
|
++_index;
|
|
return true;
|
|
}
|
|
|
|
if (_enumerator.MoveNext())
|
|
{
|
|
_buffer.Add(_enumerator.Current);
|
|
++_index;
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the element in the collection at the current position of the enumerator.
|
|
/// </summary>
|
|
public T Current
|
|
{
|
|
get
|
|
{
|
|
if (_index < 0 || _index >= _buffer.Count)
|
|
throw new InvalidOperationException();
|
|
return _buffer[_index];
|
|
}
|
|
}
|
|
|
|
/// <summary>
|
|
/// Sets the enumerator to its initial position, which is before the first element in the collection.
|
|
/// </summary>
|
|
public void Reset()
|
|
{
|
|
_enumerator.Reset();
|
|
_buffer.Clear();
|
|
_index = -1;
|
|
}
|
|
|
|
/// <summary>
|
|
/// Performs application-defined tasks associated with freeing, releasing, or resetting unmanaged resources.
|
|
/// </summary>
|
|
public void Dispose()
|
|
{
|
|
_enumerator.Dispose();
|
|
}
|
|
|
|
/// <summary>
|
|
/// Gets the element in the collection at the current position of the enumerator.
|
|
/// </summary>
|
|
object System.Collections.IEnumerator.Current => Current;
|
|
}
|
|
}
|