add function to remove all components of the same type #30

headers/ecs.hpp/ecs.hpp

@@ -679,6 +679,12 @@ namespace ecs_hpp
                 return components_.unordered_erase(id);
             }
 
+            std::size_t remove_all() noexcept {
+                const std::size_t count = components_.size();
+                components_.clear();
+                return count;
+            }
+
             T* find(entity_id id) noexcept {
                 return components_.find(id);
             }
@@ -744,6 +750,12 @@ namespace ecs_hpp
                 return components_.unordered_erase(id);
             }
 
+            std::size_t remove_all() noexcept {
+                const std::size_t count = components_.size();
+                components_.clear();
+                return count;
+            }
+
             T* find(entity_id id) noexcept {
                 return components_.has(id)
                     ? &empty_value_
@@ -1260,6 +1272,9 @@ namespace ecs_hpp
 
         std::size_t remove_all_components(const uentity& ent) noexcept;
 
+        template < typename T >
+        std::size_t remove_all_components() noexcept;
+
         template < typename T >
         T& get_component(const uentity& ent);
         template < typename T >
@@ -2190,6 +2205,14 @@ namespace ecs_hpp
         return removed_count;
     }
 
+    template < typename T >
+    std::size_t registry::remove_all_components() noexcept {
+        detail::component_storage<T>* storage = find_storage_<T>();
+        return storage
+            ? storage->remove_all()
+            : 0u;
+    }
+
     template < typename T >
     T& registry::get_component(const uentity& ent) {
         assert(valid_entity(ent));

untests/ecs_tests.cpp

@@ -565,6 +565,33 @@ TEST_CASE("registry") {
             REQUIRE_FALSE(c2);
             REQUIRE_FALSE(as_const(c2));
         }
+        {
+            ecs::registry w;
+
+            ecs::entity e1 = w.create_entity();
+            e1.assign_component<position_c>();
+
+            ecs::entity e2 = w.create_entity();
+            e2.assign_component<position_c>();
+            e2.assign_component<velocity_c>();
+
+            ecs::entity e3 = w.create_entity();
+            e3.assign_component<position_c>();
+            e3.assign_component<velocity_c>();
+
+            REQUIRE(w.component_count<position_c>() == 3u);
+            REQUIRE(w.component_count<velocity_c>() == 2u);
+
+            REQUIRE(w.remove_all_components<position_c>() == 3u);
+            REQUIRE(w.component_count<position_c>() == 0u);
+            REQUIRE(w.component_count<velocity_c>() == 2u);
+
+            REQUIRE(w.remove_all_components<velocity_c>() == 2u);
+            REQUIRE(w.component_count<position_c>() == 0u);
+            REQUIRE(w.component_count<velocity_c>() == 0u);
+
+            REQUIRE(w.remove_all_components<movable_c>() == 0u);
+        }
     }
     SECTION("prototypes") {
         {