1 /* 2 * Copyright 2014 Google Inc. All rights reserved. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #ifndef FRUIT_COMPONENT_FUNCTION_H 18 #define FRUIT_COMPONENT_FUNCTION_H 19 20 #include <fruit/impl/fruit_internal_forward_decls.h> 21 22 namespace fruit { 23 24 /** 25 * See fruit::componentFunction() helper for how to construct a ComponentFunction, and see 26 * PartialComponent::installComponentFunctions() for more information on using ComponentFunction objects. 27 */ 28 template <typename ComponentType, typename... ComponentFunctionArgs> 29 class ComponentFunction { 30 private: 31 ComponentType (*getComponent)(ComponentFunctionArgs...); 32 std::tuple<ComponentFunctionArgs...> args_tuple; 33 34 /** 35 * This is (intentionally) private, use fruit::componentFunction() to construct ComponentFunction objects. 36 */ 37 explicit ComponentFunction(ComponentType (*getComponent)(ComponentFunctionArgs...), ComponentFunctionArgs... args); 38 39 friend struct fruit::impl::ComponentStorageEntry; 40 41 public: 42 // Prefer using the simpler componentFunction() below instead of this. 43 template <typename... ActualArgs> 44 static ComponentFunction<ComponentType, ComponentFunctionArgs...> create( 45 ComponentType (*getComponent)(ComponentFunctionArgs...), ActualArgs&&... args); 46 47 ComponentFunction(const ComponentFunction&) = default; 48 ComponentFunction(ComponentFunction&&) noexcept = default; 49 50 ComponentFunction& operator=(const ComponentFunction&) = default; 51 ComponentFunction& operator=(ComponentFunction&& other) noexcept { 52 args_tuple = std::move(other.args_tuple); 53 return *this; 54 } 55 56 ComponentType operator()(); 57 }; 58 59 60 /** 61 * This function allows to easily construct a ComponentFunction without explicitly mentioning its type. 62 * See PartialComponent::installComponentFunctions() for more information on using ComponentFunction. 63 */ 64 template <typename... ComponentParams, typename... FormalArgs, typename... ActualArgs> 65 ComponentFunction<fruit::Component<ComponentParams...>, FormalArgs...> componentFunction( 66 fruit::Component<ComponentParams...> (*getComponent)(FormalArgs...), 67 ActualArgs&&... args); 68 69 } 70 71 #include <fruit/impl/component_function.defn.h> 72 73 #endif // FRUIT_COMPONENT_FUNCTION_H 74