tvl-depot/third_party/abseil_cpp/absl/flags/usage.cc
Vincent Ambo fc8dc48020 Add 'third_party/abseil_cpp/' from commit '768eb2ca2857342673fcd462792ce04b8bac3fa3'
git-subtree-dir: third_party/abseil_cpp
git-subtree-mainline: ffb2ae54be
git-subtree-split: 768eb2ca28
2020-05-20 02:32:24 +01:00

65 lines
2.3 KiB
C++

//
// 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 <stdlib.h>
#include <string>
#include "absl/base/attributes.h"
#include "absl/base/config.h"
#include "absl/base/const_init.h"
#include "absl/base/thread_annotations.h"
#include "absl/flags/internal/usage.h"
#include "absl/strings/string_view.h"
#include "absl/synchronization/mutex.h"
namespace absl {
ABSL_NAMESPACE_BEGIN
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";
}
ABSL_NAMESPACE_END
} // namespace absl