Use "if constexpr" provided by C++17

src/CMakeLists.txt

@@ -31,7 +31,7 @@ set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wpedantic")
 set(CMAKE_CXX_FLAGS_DEBUG "-O0 -g")
 set(CMAKE_CXX_FLAGS_RELEASE "-O3 -D NDEBUG")
 
-target_compile_features(EntityComponentSystem INTERFACE cxx_std_14)
+target_compile_features(EntityComponentSystem INTERFACE cxx_std_17)
 
 if(NOT CMAKE_BUILD_TYPE AND NOT CMAKE_CONFIGURATION_TYPES)
     message(STATUS "Setting build type to 'Debug', none was specified.")
@@ -53,7 +53,7 @@ if(GTEST_FOUND)
     add_executable(UnitTests ${UnitTests_SOURCES})
     target_link_libraries(UnitTests EntityComponentSystem ${GTEST_LIBRARIES})
     target_include_directories(UnitTests PUBLIC ${GTEST_INCLUDE_DIR})
-    target_compile_features(UnitTests PUBLIC cxx_std_14)
+    target_compile_features(UnitTests PUBLIC cxx_std_17)
 
     enable_testing()
     add_test(NAME UnitTests COMMAND UnitTests)

src/EC/Bitset.hpp

@@ -66,7 +66,7 @@ namespace EC
             Bitset<ComponentsList, TagsList> bitset;
 
             EC::Meta::forEach<Contents>([&bitset] (auto t) {
-                if(EC::Meta::Contains<decltype(t), Combined>::value)
+                if constexpr (EC::Meta::Contains<decltype(t), Combined>::value)
                 {
                     bitset[EC::Meta::IndexOf<decltype(t), Combined>::value] =
                         true;

src/EC/Manager.hpp

@@ -32,7 +32,6 @@
 #include "Meta/Matching.hpp"
 #include "Meta/ForEachWithIndex.hpp"
 #include "Meta/ForEachDoubleTuple.hpp"
-#include "Meta/IndexOf.hpp"
 #include "Bitset.hpp"
 
 namespace EC
@@ -67,7 +66,7 @@ namespace EC
         template <typename... Types>
         struct Storage
         {
-            using type = std::tuple<std::vector<Types>..., std::vector<char> >;
+            using type = std::tuple<std::vector<Types>...>;
         };
         using ComponentsStorage =
             typename EC::Meta::Morph<ComponentsList, Storage<> >::type;
@@ -242,15 +241,10 @@ namespace EC
         template <typename Component>
         Component* getEntityData(const std::size_t& index)
         {
-            constexpr auto componentIndex = EC::Meta::IndexOf<
+            if constexpr (EC::Meta::Contains<Component, Components>::value)
-                Component, Components>::value;
-            if(componentIndex < Components::size)
             {
-                // Cast required due to compiler thinking that an invalid
+                return &std::get<std::vector<Component> >(componentsStorage)
-                // Component is needed even though the enclosing if statement
+                    .at(index);
-                // prevents this from ever happening.
-                return (Component*) &std::get<componentIndex>(
-                    componentsStorage).at(index);
             }
             else
             {
@@ -295,15 +289,10 @@ namespace EC
         template <typename Component>
         const Component* getEntityData(const std::size_t& index) const
         {
-            constexpr auto componentIndex = EC::Meta::IndexOf<
+            if constexpr (EC::Meta::Contains<Component, Components>::value)
-                Component, Components>::value;
-            if(componentIndex < Components::size)
             {
-                // Cast required due to compiler thinking that an invalid
+                return &std::get<std::vector<Component> >(componentsStorage)
-                // Component is needed even though the enclosing if statement
+                    .at(index);
-                // prevents this from ever happening.
-                return (Component*) &std::get<componentIndex>(
-                    componentsStorage).at(index);
             }
             else
             {
@@ -395,27 +384,25 @@ namespace EC
         template <typename Component, typename... Args>
         void addComponent(const std::size_t& entityID, Args&&... args)
         {
-            if(!EC::Meta::Contains<Component, Components>::value
+            if constexpr (!EC::Meta::Contains<Component, Components>::value)
-                || !isAlive(entityID))
             {
                 return;
             }
+            else
+            {
+                if(!isAlive(entityID))
+                {
+                    return;
+                }
+                Component component(std::forward<Args>(args)...);
 
-            Component component(std::forward<Args>(args)...);
+                std::get<BitsetType>(
+                    entities[entityID]
+                ).template getComponentBit<Component>() = true;
 
-            std::get<BitsetType>(
+                std::get<std::vector<Component> >(componentsStorage)[entityID]
-                entities[entityID]
+                    = std::move(component);
-            ).template getComponentBit<Component>() = true;
+            }
-
-            constexpr auto index =
-                EC::Meta::IndexOf<Component, Components>::value;
-
-            // Cast required due to compiler thinking that vector<char> at
-            // index = Components::size is being used, even if the previous
-            // if statement will prevent this from ever happening.
-            (*((std::vector<Component>*)(&std::get<index>(
-                componentsStorage
-            ))))[entityID] = std::move(component);
         }
 
         /*!
@@ -432,15 +419,20 @@ namespace EC
         template <typename Component>
         void removeComponent(const std::size_t& entityID)
         {
-            if(!EC::Meta::Contains<Component, Components>::value
+            if constexpr (!EC::Meta::Contains<Component, Components>::value)
-                || !isAlive(entityID))
             {
                 return;
             }
-
+            else
-            std::get<BitsetType>(
+            {
-                entities[entityID]
+                if(!isAlive(entityID))
-            ).template getComponentBit<Component>() = false;
+                {
+                    return;
+                }
+                std::get<BitsetType>(
+                    entities[entityID]
+                ).template getComponentBit<Component>() = false;
+            }
         }
 
         /*!
@@ -454,15 +446,20 @@ namespace EC
         template <typename Tag>
         void addTag(const std::size_t& entityID)
         {
-            if(!EC::Meta::Contains<Tag, Tags>::value
+            if constexpr (!EC::Meta::Contains<Tag, Tags>::value)
-                || !isAlive(entityID))
             {
                 return;
             }
-
+            else
-            std::get<BitsetType>(
+            {
-                entities[entityID]
+                if(!isAlive(entityID))
-            ).template getTagBit<Tag>() = true;
+                {
+                    return;
+                }
+                std::get<BitsetType>(
+                    entities[entityID]
+                ).template getTagBit<Tag>() = true;
+            }
         }
 
     /*!
@@ -478,15 +475,20 @@ namespace EC
         template <typename Tag>
         void removeTag(const std::size_t& entityID)
         {
-            if(!EC::Meta::Contains<Tag, Tags>::value
+            if constexpr (!EC::Meta::Contains<Tag, Tags>::value)
-                || !isAlive(entityID))
             {
                 return;
             }
-
+            else
-            std::get<BitsetType>(
+            {
-                entities[entityID]
+                if(!isAlive(entityID))
-            ).template getTagBit<Tag>() = false;
+                {
+                    return;
+                }
+                std::get<BitsetType>(
+                    entities[entityID]
+                ).template getTagBit<Tag>() = false;
+            }
         }
 
     private: