1 // Copyright 2020 The Pigweed Authors 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); you may not 4 // use this file except in compliance with the License. You may obtain a copy of 5 // the License at 6 // 7 // https://www.apache.org/licenses/LICENSE-2.0 8 // 9 // Unless required by applicable law or agreed to in writing, software 10 // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 11 // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 12 // License for the specific language governing permissions and limitations under 13 // the License. 14 #pragma once 15 16 #include "pw_rpc/internal/method.h" 17 18 namespace pw::rpc::internal { 19 20 // Gets a Method object from a generated RPC service class. Getter functions are 21 // provided for each supported method implementation. The 22 // 23 // To ensure the MethodUnion actually holds the requested method type, the 24 // method ID is accessed in a static_assert. It is invalid to access an unset 25 // union member in a constant expression, so this results in a compiler error. 26 class MethodLookup { 27 public: 28 MethodLookup() = delete; 29 30 template <typename Service, uint32_t kMethodId> GetRawMethod()31 static constexpr const auto& GetRawMethod() { 32 const auto& method = GetMethodUnion<Service, kMethodId>().raw_method(); 33 static_assert(method.id() == kMethodId, "Incorrect method implementation"); 34 return method; 35 } 36 37 template <typename Service, uint32_t kMethodId> GetNanopbMethod()38 static constexpr const auto& GetNanopbMethod() { 39 const auto& method = GetMethodUnion<Service, kMethodId>().nanopb_method(); 40 static_assert(method.id() == kMethodId, "Incorrect method implementation"); 41 return method; 42 } 43 44 private: 45 template <typename Service, uint32_t kMethodId> GetMethodUnion()46 static constexpr const auto& GetMethodUnion() { 47 constexpr auto method = GetMethodUnionPointer<Service>(kMethodId); 48 static_assert(method != nullptr, 49 "The selected function is not an RPC service method"); 50 return *method; 51 } 52 53 template <typename Service> decltype(Service::kPwRpcMethods)54 static constexpr typename decltype(Service::kPwRpcMethods)::const_pointer 55 GetMethodUnionPointer(uint32_t kMethodId) { 56 for (size_t i = 0; i < Service::kPwRpcMethodIds.size(); ++i) { 57 if (Service::kPwRpcMethodIds[i] == kMethodId) { 58 return &Service::kPwRpcMethods[i]; 59 } 60 } 61 return nullptr; 62 } 63 }; 64 65 } // namespace pw::rpc::internal 66