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//
// 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
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