osu/osu.Game/Utils/OrderAttribute.cs

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// Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
// See the LICENCE file in the repository root for full licence text.
using System;
using System.Collections.Generic;
using System.Linq;
namespace osu.Game.Utils
{
public static class OrderAttributeUtils
{
/// <summary>
/// Get values of an enum in order. Supports custom ordering via <see cref="OrderAttribute"/>.
/// </summary>
public static IEnumerable<T> GetValuesInOrder<T>()
{
var type = typeof(T);
if (!type.IsEnum)
throw new InvalidOperationException("T must be an enum");
IEnumerable<T> items = (T[])Enum.GetValues(type);
if (Attribute.GetCustomAttribute(type, typeof(HasOrderedElementsAttribute)) == null)
return items;
return items.OrderBy(i =>
{
if (type.GetField(i.ToString()).GetCustomAttributes(typeof(OrderAttribute), false).FirstOrDefault() is OrderAttribute attr)
return attr.Order;
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throw new ArgumentException($"Not all values of {nameof(T)} have {nameof(OrderAttribute)} specified.");
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});
}
}
[AttributeUsage(AttributeTargets.Field)]
public class OrderAttribute : Attribute
{
public readonly int Order;
public OrderAttribute(int order)
{
Order = order;
}
}
[AttributeUsage(AttributeTargets.Enum)]
public class HasOrderedElementsAttribute : Attribute
{
}
}