voidify.h (1735B)
1 // Copyright 2022 The Abseil Authors. 2 // 3 // Licensed under the Apache License, Version 2.0 (the "License"); 4 // you may not use this file except in compliance with the License. 5 // You may obtain a copy of 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, 11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 // See the License for the specific language governing permissions and 13 // limitations under the License. 14 // 15 // ----------------------------------------------------------------------------- 16 // File: log/internal/voidify.h 17 // ----------------------------------------------------------------------------- 18 // 19 // This class does the dispatching of the completed `absl::LogEntry` to 20 // applicable `absl::LogSink`s, and is used to explicitly ignore values in the 21 // conditional logging macros. This avoids compiler warnings like "value 22 // computed is not used" and "statement has no effect". 23 24 #ifndef ABSL_LOG_INTERNAL_VOIDIFY_H_ 25 #define ABSL_LOG_INTERNAL_VOIDIFY_H_ 26 27 #include "absl/base/attributes.h" 28 #include "absl/base/config.h" 29 30 namespace absl { 31 ABSL_NAMESPACE_BEGIN 32 namespace log_internal { 33 34 class Voidify final { 35 public: 36 // This has to be an operator with a precedence lower than << but higher than 37 // ?: 38 template <typename T> 39 ABSL_ATTRIBUTE_COLD void operator&&(T&& message) const&& { 40 // The dispatching of the completed `absl::LogEntry` to applicable 41 // `absl::LogSink`s happens here. 42 message.Flush(); 43 } 44 }; 45 46 } // namespace log_internal 47 ABSL_NAMESPACE_END 48 } // namespace absl 49 50 #endif // ABSL_LOG_INTERNAL_VOIDIFY_H_