MoonTools.ECS/src/Rev2/ArchetypeSignature.cs

using System;
using System.Collections.Generic;

namespace MoonTools.ECS.Rev2;

internal class ArchetypeSignature : IEquatable<ArchetypeSignature>
{
	public static ArchetypeSignature Empty = new ArchetypeSignature(0);

	List<uint> Ids;

	public int Count => Ids.Count;

	public TypeId this[int i] => new TypeId(Ids[i]);

	public ArchetypeSignature()
	{
		Ids = new List<uint>();
	}

	public ArchetypeSignature(int capacity)
	{
		Ids = new List<uint>(capacity);
	}

	// Maintains sorted order
	public void Insert(TypeId componentId)
	{
		var index = Ids.BinarySearch(componentId.Value);

		if (index < 0)
		{
			Ids.Insert(~index, componentId.Value);
		}
	}

	public void Remove(TypeId componentId)
	{
		var index = Ids.BinarySearch(componentId.Value);

		if (index >= 0)
		{
			Ids.RemoveAt(index);
		}
	}

	public void CopyTo(ArchetypeSignature other)
	{
		other.Ids.AddRange(Ids);
	}

	public override bool Equals(object? obj)
	{
		return obj is ArchetypeSignature signature && Equals(signature);
	}

	public bool Equals(ArchetypeSignature? other)
	{
		if (other == null)
		{
			return false;
		}

		if (Ids.Count != other.Ids.Count)
		{
			return false;
		}

		for (int i = 0; i < Ids.Count; i += 1)
		{
			if (Ids[i] != other.Ids[i])
			{
				return false;
			}
		}

		return true;
	}

	public override int GetHashCode()
	{
		var hashcode = 1;

		foreach (var id in Ids)
		{
			hashcode = HashCode.Combine(hashcode, id);
		}

		return hashcode;
	}
}