Line data    Source code

       1              : /*
       2              :  *    Copyright (c) 2021 Project CHIP Authors
       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              : #pragma once
      18              : 
      19              : #include <string.h>
      20              : #include <type_traits>
      21              : 
      22              : #include <lib/core/CHIPConfig.h>
      23              : 
      24              : namespace chip {
      25              : 
      26              : class LambdaBridge
      27              : {
      28              : public:
      29              :     // Use initialize instead of constructor because this class has to be trivial
      30              :     template <typename Lambda>
      31           61 :     void Initialize(const Lambda & lambda)
      32              :     {
      33              :         // memcpy is used to move the lambda into the event queue, so it must be trivially copyable
      34              :         static_assert(std::is_trivially_copyable<Lambda>::value, "lambda must be trivially copyable");
      35              :         static_assert(sizeof(Lambda) <= CHIP_CONFIG_LAMBDA_EVENT_SIZE, "lambda too large");
      36              :         static_assert(CHIP_CONFIG_LAMBDA_EVENT_ALIGN % alignof(Lambda) == 0, "lambda align too large");
      37              : 
      38              :         // Implicit cast a capture-less lambda into a raw function pointer.
      39           85 :         mLambdaProxy = [](const LambdaStorage & body) { (*reinterpret_cast<const Lambda *>(&body))(); };
      40           61 :         ::memcpy(&mLambdaBody, &lambda, sizeof(Lambda));
      41           61 :     }
      42              : 
      43           24 :     void operator()() const { mLambdaProxy(mLambdaBody); }
      44              : 
      45              : private:
      46              :     using LambdaStorage = std::aligned_storage_t<CHIP_CONFIG_LAMBDA_EVENT_SIZE, CHIP_CONFIG_LAMBDA_EVENT_ALIGN>;
      47              :     void (*mLambdaProxy)(const LambdaStorage & body);
      48              :     LambdaStorage mLambdaBody;
      49              : };
      50              : 
      51              : static_assert(std::is_trivial<LambdaBridge>::value, "LambdaBridge is not trivial");
      52              : 
      53              : } // namespace chip