// // Copyright 2019 The Abseil Authors. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // https://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #include "absl/flags/usage.h" #include <string> #include "absl/flags/internal/usage.h" #include "absl/synchronization/mutex.h" namespace absl { namespace flags_internal { namespace { ABSL_CONST_INIT absl::Mutex usage_message_guard(absl::kConstInit); ABSL_CONST_INIT std::string* program_usage_message ABSL_GUARDED_BY(usage_message_guard) = nullptr; } // namespace } // namespace flags_internal // -------------------------------------------------------------------- // Sets the "usage" message to be used by help reporting routines. void SetProgramUsageMessage(absl::string_view new_usage_message) { absl::MutexLock l(&flags_internal::usage_message_guard); if (flags_internal::program_usage_message != nullptr) { ABSL_INTERNAL_LOG(FATAL, "SetProgramUsageMessage() called twice."); std::exit(1); } flags_internal::program_usage_message = new std::string(new_usage_message); } // -------------------------------------------------------------------- // Returns the usage message set by SetProgramUsageMessage(). // Note: We able to return string_view here only because calling // SetProgramUsageMessage twice is prohibited. absl::string_view ProgramUsageMessage() { absl::MutexLock l(&flags_internal::usage_message_guard); return flags_internal::program_usage_message != nullptr ? absl::string_view(*flags_internal::program_usage_message) : "Warning: SetProgramUsageMessage() never called"; } } // namespace absl