From eb3d592d1898b2f59887cf00780e24e2ff7810e8 Mon Sep 17 00:00:00 2001
From: Mathias Agopian <mathias@google.com>
Date: Tue, 14 Apr 2026 23:51:24 -0700
Subject: [PATCH] expose EntityManager::getIndex() publicly

This can be needed for interactions with an outside entity system.
Use with caution.
---
 libs/utils/include/utils/EntityManager.h | 25 +++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/libs/utils/include/utils/EntityManager.h b/libs/utils/include/utils/EntityManager.h
index 5e2eaa1b00..ccefa06bbb 100644
--- a/libs/utils/include/utils/EntityManager.h
+++ b/libs/utils/include/utils/EntityManager.h
@@ -78,7 +78,7 @@ public:
 
     // Return whether the given Entity has been destroyed (false) or not (true).
     // Thread safe.
-    bool isAlive(Entity e) const noexcept {
+    bool isAlive(Entity const e) const noexcept {
         assert(getIndex(e) < RAW_INDEX_COUNT);
         return (!e.isNull()) && (getGeneration(e) == mGens[getIndex(e)]);
     }
@@ -94,7 +94,7 @@ public:
     /* no user serviceable parts below */
 
     // current generation of the given index. Use for debugging and testing.
-    uint8_t getGenerationForIndex(size_t index) const noexcept {
+    uint8_t getGenerationForIndex(size_t const index) const noexcept {
         return mGens[index];
     }
 
@@ -107,6 +107,11 @@ public:
     void dumpActiveEntities(utils::io::ostream& out) const;
 #endif
 
+    // use carefully, several entities can have the same index.
+    static Entity::Type getIndex(Entity const e) noexcept  {
+        return e.getId() & INDEX_MASK;
+    }
+
 private:
     friend class EntityManagerImpl;
     EntityManager();
@@ -114,22 +119,20 @@ private:
 
     // GENERATION_SHIFT determines how many simultaneous Entities are available, the
     // minimum memory requirement is 2^GENERATION_SHIFT bytes.
-    static constexpr const int GENERATION_SHIFT = 17;
-    static constexpr const size_t RAW_INDEX_COUNT = (1 << GENERATION_SHIFT);
-    static constexpr const Entity::Type INDEX_MASK = (1 << GENERATION_SHIFT) - 1u;
+    static constexpr int GENERATION_SHIFT = 17;
+    static constexpr size_t RAW_INDEX_COUNT = (1 << GENERATION_SHIFT);
+    static constexpr Entity::Type INDEX_MASK = (1 << GENERATION_SHIFT) - 1u;
 
-    static inline Entity::Type getGeneration(Entity e) noexcept {
+    static Entity::Type getGeneration(Entity const e) noexcept {
         return e.getId() >> GENERATION_SHIFT;
     }
-    static inline Entity::Type getIndex(Entity e) noexcept  {
-        return e.getId() & INDEX_MASK;
-    }
-    static inline Entity::Type makeIdentity(Entity::Type g, Entity::Type i) noexcept {
+
+    static Entity::Type makeIdentity(Entity::Type const g, Entity::Type const i) noexcept {
         return (g << GENERATION_SHIFT) | (i & INDEX_MASK);
     }
 
     // stores the generation of each index.
-    uint8_t * const mGens;
+    uint8_t* const mGens;
 };
 
 } // namespace utils