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