encompass-cs/encompass-cs/EntitySetQueryBuilder.cs

using System;
using System.Collections.Generic;
using Encompass.Collections;

namespace Encompass
{
    /// <summary>
    /// EntitySetQuery is used to efficiently obtain a set of Entities that have all required Components and do not have any forbidden Components.
    /// </summary>
    public class EntitySetQueryBuilder
    {
        internal EntitySetQueryBuilder(EntityManager entityManager, ComponentUpdateManager componentUpdateManager, IEnumerable<Type> pendingTypes, IEnumerable<Type> existingTypes)
        {
            EntityManager = entityManager;
            ComponentUpdateManager = componentUpdateManager;
            WithMask = BitSet1024Builder.Zeroes();
            WithoutMask = BitSet1024Builder.Zeroes();
            
            PendingMask = BitSet1024Builder.Zeroes();
            foreach (var type in pendingTypes)
            {
                PendingMask = PendingMask.Set(componentUpdateManager.TypeToIndex[type]);
            }

            ExistingMask = BitSet1024Builder.Zeroes();
            foreach (var type in existingTypes)
            {
                ExistingMask = ExistingMask.Set(componentUpdateManager.TypeToIndex[type]);
            }
        }

        private EntityManager EntityManager { get; }
        private ComponentUpdateManager ComponentUpdateManager { get; }
        private BitSet1024 WithMask { get; set; }
        private BitSet1024 WithoutMask { get; set; }
        private BitSet1024 PendingMask { get; set; }
        private BitSet1024 ExistingMask { get; set; }

        /// <summary>
        /// Designates that the given component type is required.
        /// </summary>
        public EntitySetQueryBuilder With<TComponent>() where TComponent : struct, IComponent
        {
            WithMask = WithMask.Set(ComponentUpdateManager.TypeToIndex[typeof(TComponent)]);
            return this;
        }

        /// <summary>
        /// Designates that the given component type is forbidden.
        /// </summary>
        public EntitySetQueryBuilder Without<TComponent>() where TComponent : struct, IComponent
        {
            WithoutMask = WithoutMask.Set(ComponentUpdateManager.TypeToIndex[typeof(TComponent)]);
            return this;
        }

        public EntitySetQuery Build()
        {
            return new EntitySetQuery(
                EntityManager,
                ComponentUpdateManager,
                WithMask.And(PendingMask),
                WithMask.And(ExistingMask),
                WithoutMask.And(PendingMask),
                WithoutMask.And(ExistingMask),
                WithMask.Not()
            );
        }
    }
}