From 323fb0e209d375ea964a7f5ec372863533ae4990 Mon Sep 17 00:00:00 2001
From: cosmonaut <evan@moonside.games>
Date: Thu, 31 Mar 2022 16:15:30 -0700
Subject: [PATCH] add Exists API call to check if entity exists

---
 src/EntityComponentReader.cs | 5 +++++
 src/EntityStorage.cs         | 5 +++++
 src/IDStorage.cs             | 5 +++++
 3 files changed, 15 insertions(+)

diff --git a/src/EntityComponentReader.cs b/src/EntityComponentReader.cs
index f547518..82884ab 100644
--- a/src/EntityComponentReader.cs
+++ b/src/EntityComponentReader.cs
@@ -51,4 +51,9 @@ public abstract class EntityComponentReader
 	{
 		return ref ComponentDepot.GetEntity<TComponent>();
 	}
+
+	protected bool Exists(in Entity entity)
+	{
+		return EntityStorage.Exists(entity);
+	}
 }
diff --git a/src/EntityStorage.cs b/src/EntityStorage.cs
index ebbed67..ccadb1a 100644
--- a/src/EntityStorage.cs
+++ b/src/EntityStorage.cs
@@ -9,6 +9,11 @@ internal class EntityStorage
 		return new Entity(idStorage.NextID());
 	}
 
+	public bool Exists(in Entity entity)
+	{
+		return idStorage.Taken(entity.ID);
+	}
+
 	public void Destroy(in Entity entity)
 	{
 		idStorage.Release(entity.ID);
diff --git a/src/IDStorage.cs b/src/IDStorage.cs
index 011c274..c46e238 100644
--- a/src/IDStorage.cs
+++ b/src/IDStorage.cs
@@ -20,6 +20,11 @@ internal class IDStorage
 		}
 	}
 
+	public bool Taken(int id)
+	{
+		return !availableIDs.Contains(id) && id < nextID;
+	}
+
 	public void Release(int id)
 	{
 		availableIDs.Push(id);