From 4ad411e320b109c8d955f7779c0f7af034b6d642 Mon Sep 17 00:00:00 2001
From: Michele Caini <michele.caini@gmail.com>
Date: Wed, 28 Oct 2020 22:58:26 +0100
Subject: [PATCH] traits: is_eto_eligible[_v] -> is_empty[_v], internal version

---
 src/entt/core/type_traits.hpp |  4 ++--
 src/entt/entity/group.hpp     | 22 +++++++++++-----------
 src/entt/entity/pool.hpp      |  4 ++--
 src/entt/entity/storage.hpp   |  2 +-
 src/entt/entity/view.hpp      | 16 +++++++---------
 5 files changed, 23 insertions(+), 25 deletions(-)

diff --git a/src/entt/core/type_traits.hpp b/src/entt/core/type_traits.hpp
index 7c3012637..f1e92806e 100644
--- a/src/entt/core/type_traits.hpp
+++ b/src/entt/core/type_traits.hpp
@@ -309,7 +309,7 @@ inline constexpr auto is_applicable_r_v = is_applicable_r<Ret, Func, Args>::valu
  * @tparam Type Potential empty type.
  */
 template<typename Type, typename = void>
-struct is_eto_eligible
+struct is_empty
     : ENTT_IS_EMPTY(Type)
 {};
 
@@ -319,7 +319,7 @@ struct is_eto_eligible
  * @tparam Type Potential empty type.
  */
 template<typename Type>
-inline constexpr auto is_eto_eligible_v = is_eto_eligible<Type>::value;
+inline constexpr auto is_empty_v = is_empty<Type>::value;
 
 
 /**
diff --git a/src/entt/entity/group.hpp b/src/entt/entity/group.hpp
index 1e68f9435..f21f5a526 100644
--- a/src/entt/entity/group.hpp
+++ b/src/entt/entity/group.hpp
@@ -129,11 +129,11 @@ class basic_group<Entity, exclude_t<Exclude...>, get_t<Get...>> final {
     public:
         using iterator = iterable_group_iterator<
             typename basic_sparse_set<Entity>::iterator,
-            type_list_cat_t<std::conditional_t<is_eto_eligible_v<Get>, type_list<>, type_list<Get>>...>
+            type_list_cat_t<std::conditional_t<is_empty_v<Get>, type_list<>, type_list<Get>>...>
         >;
         using reverse_iterator = iterable_group_iterator<
             typename basic_sparse_set<Entity>::reverse_iterator,
-            type_list_cat_t<std::conditional_t<is_eto_eligible_v<Get>, type_list<>, type_list<Get>>...>
+            type_list_cat_t<std::conditional_t<is_empty_v<Get>, type_list<>, type_list<Get>>...>
         >;
 
         [[nodiscard]] iterator begin() const ENTT_NOEXCEPT {
@@ -408,7 +408,7 @@ public:
 
         if constexpr(sizeof...(Component) == 0) {
             return std::tuple_cat([entt](auto *cpool) {
-                if constexpr(is_eto_eligible_v<typename std::remove_reference_t<decltype(*cpool)>::value_type>) {
+                if constexpr(is_empty_v<typename std::remove_reference_t<decltype(*cpool)>::value_type>) {
                     return std::tuple{};
                 } else {
                     return std::forward_as_tuple(cpool->get(entt));
@@ -445,7 +445,7 @@ public:
      */
     template<typename Func>
     void each(Func func) const {
-        traverse(std::move(func), (std::conditional_t<is_eto_eligible_v<Get>, type_list<>, type_list<Get>>{} + ...));
+        traverse(std::move(func), (std::conditional_t<is_empty_v<Get>, type_list<>, type_list<Get>>{} + ...));
     }
 
     /**
@@ -661,13 +661,13 @@ class basic_group<Entity, exclude_t<Exclude...>, get_t<Get...>, Owned...> final
     public:
         using iterator = iterable_group_iterator<
             typename basic_sparse_set<Entity>::iterator,
-            type_list_cat_t<std::conditional_t<is_eto_eligible_v<Owned>, type_list<>, type_list<decltype(std::declval<pool_type<Owned>>().end())>>...>,
-            type_list_cat_t<std::conditional_t<is_eto_eligible_v<Get>, type_list<>, type_list<Get>>...>
+            type_list_cat_t<std::conditional_t<is_empty_v<Owned>, type_list<>, type_list<decltype(std::declval<pool_type<Owned>>().end())>>...>,
+            type_list_cat_t<std::conditional_t<is_empty_v<Get>, type_list<>, type_list<Get>>...>
         >;
         using reverse_iterator = iterable_group_iterator<
             typename basic_sparse_set<Entity>::reverse_iterator,
-            type_list_cat_t<std::conditional_t<is_eto_eligible_v<Owned>, type_list<>, type_list<decltype(std::declval<pool_type<Owned>>().rbegin())>>...>,
-            type_list_cat_t<std::conditional_t<is_eto_eligible_v<Get>, type_list<>, type_list<Get>>...>
+            type_list_cat_t<std::conditional_t<is_empty_v<Owned>, type_list<>, type_list<decltype(std::declval<pool_type<Owned>>().rbegin())>>...>,
+            type_list_cat_t<std::conditional_t<is_empty_v<Get>, type_list<>, type_list<Get>>...>
         >;
 
         [[nodiscard]] iterator begin() const ENTT_NOEXCEPT {
@@ -957,7 +957,7 @@ public:
             auto filter = [entt, index = std::get<0>(pools)->index(entt)](auto *cpool) {
                 using value_type = typename std::remove_reference_t<decltype(*cpool)>::value_type;
 
-                if constexpr(is_eto_eligible_v<value_type>) {
+                if constexpr(is_empty_v<value_type>) {
                     return std::tuple{};
                 } else if constexpr((std::is_same_v<value_type, std::remove_const_t<Owned>> || ...)) {
                     return std::forward_as_tuple(cpool->raw()[index]);
@@ -999,8 +999,8 @@ public:
     template<typename Func>
     void each(Func func) const {
         traverse(std::move(func),
-            (std::conditional_t<is_eto_eligible_v<Owned>, type_list<>, type_list<Owned>>{} + ...),
-            (type_list<>{} + ... + std::conditional_t<is_eto_eligible_v<Get>, type_list<>, type_list<Get>>{}));
+            (std::conditional_t<is_empty_v<Owned>, type_list<>, type_list<Owned>>{} + ...),
+            (type_list<>{} + ... + std::conditional_t<is_empty_v<Get>, type_list<>, type_list<Get>>{}));
     }
 
     /**
diff --git a/src/entt/entity/pool.hpp b/src/entt/entity/pool.hpp
index 03af45732..380dd4bf7 100644
--- a/src/entt/entity/pool.hpp
+++ b/src/entt/entity/pool.hpp
@@ -179,7 +179,7 @@ struct sigh_pool_mixin: Pool {
         Pool::emplace(owner, entity, std::forward<Args>(args)...);
         construction.publish(owner, entity);
 
-        if constexpr(!is_eto_eligible_v<value_type>) {
+        if constexpr(!is_empty_v<value_type>) {
             return this->get(entity);
         }
     }
@@ -244,7 +244,7 @@ struct sigh_pool_mixin: Pool {
      */
     template<typename... Func>
     decltype(auto) patch(basic_registry<entity_type> &owner, const entity_type entity, [[maybe_unused]] Func &&... func) {
-        if constexpr(is_eto_eligible_v<value_type>) {
+        if constexpr(is_empty_v<value_type>) {
             update.publish(owner, entity);
         } else {
             Pool::patch(owner, entity, std::forward<Func>(func)...);
diff --git a/src/entt/entity/storage.hpp b/src/entt/entity/storage.hpp
index 4ab903fcb..e5dfec304 100644
--- a/src/entt/entity/storage.hpp
+++ b/src/entt/entity/storage.hpp
@@ -535,7 +535,7 @@ private:
 
 /*! @copydoc basic_storage */
 template<typename Entity, typename Type>
-class basic_storage<Entity, Type, std::enable_if_t<is_eto_eligible_v<Type>>>: public basic_sparse_set<Entity> {
+class basic_storage<Entity, Type, std::enable_if_t<is_empty_v<Type>>>: public basic_sparse_set<Entity> {
     using underlying_type = basic_sparse_set<Entity>;
 
 public:
diff --git a/src/entt/entity/view.hpp b/src/entt/entity/view.hpp
index 0091e2ad5..bf1f41788 100644
--- a/src/entt/entity/view.hpp
+++ b/src/entt/entity/view.hpp
@@ -71,7 +71,7 @@ class basic_view<Entity, exclude_t<Exclude...>, Component...> final {
     template<typename Comp>
     using pool_type = pool_t<Entity, Comp>;
 
-    using return_type = type_list_cat_t<std::conditional_t<is_eto_eligible_v<Component>, type_list<>, type_list<Component>>...>;
+    using return_type = type_list_cat_t<std::conditional_t<is_empty_v<Component>, type_list<>, type_list<Component>>...>;
     using unchecked_type = std::array<const basic_sparse_set<Entity> *, (sizeof...(Component) - 1)>;
 
     template<typename It>
@@ -290,9 +290,7 @@ class basic_view<Entity, exclude_t<Exclude...>, Component...> final {
         auto first = view->data();
 
         while(first != last) {
-            if((std::get<pool_type<Component> *>(pools)->contains(*first) && ...)
-                && !(std::get<const pool_type<Exclude> *>(filter)->contains(*first) || ...))
-            {
+            if((std::get<pool_type<Component> *>(pools)->contains(*first) && ...) && !(std::get<const pool_type<Exclude> *>(filter)->contains(*first) || ...)) {
                 const auto base = *(first++);
                 const auto chunk = (std::min)({ (std::get<pool_type<Component> *>(pools)->size() - std::get<pool_type<Component> *>(pools)->index(base))... });
                 size_type length{};
@@ -443,7 +441,7 @@ public:
 
         if constexpr(sizeof...(Comp) == 0) {
             return std::tuple_cat([entt](auto *cpool) {
-                if constexpr(is_eto_eligible_v<typename std::remove_reference_t<decltype(*cpool)>::value_type>) {
+                if constexpr(is_empty_v<typename std::remove_reference_t<decltype(*cpool)>::value_type>) {
                     return std::tuple{};
                 } else {
                     return std::forward_as_tuple(cpool->get(entt));
@@ -674,12 +672,12 @@ class basic_view<Entity, exclude_t<>, Component> final {
 
     public:
         using iterator = std::conditional_t<
-            is_eto_eligible_v<Component>,
+            is_empty_v<Component>,
             iterable_view_iterator<typename basic_sparse_set<Entity>::iterator>,
             iterable_view_iterator<typename basic_sparse_set<Entity>::iterator, decltype(std::declval<pool_type>().begin())>
         >;
         using reverse_iterator = std::conditional_t<
-            is_eto_eligible_v<Component>,
+            is_empty_v<Component>,
             iterable_view_iterator<typename basic_sparse_set<Entity>::reverse_iterator>,
             iterable_view_iterator<typename basic_sparse_set<Entity>::reverse_iterator, decltype(std::declval<pool_type>().rbegin())>
         >;
@@ -889,7 +887,7 @@ public:
     template<typename... Comp>
     [[nodiscard]] decltype(auto) get(const entity_type entt) const {
         if constexpr(sizeof...(Comp) == 0) {
-            if constexpr(is_eto_eligible_v<Component>) {
+            if constexpr(is_empty_v<Component>) {
                 return std::tuple{};
             } else {
                 return std::forward_as_tuple(pool->get(entt));
@@ -924,7 +922,7 @@ public:
      */
     template<typename Func>
     void each(Func func) const {
-        if constexpr(is_eto_eligible_v<Component>) {
+        if constexpr(is_empty_v<Component>) {
             if constexpr(std::is_invocable_v<Func, entity_type>) {
                 for(const auto entt: *this) {
                     func(entt);