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// 
// Copyright 2020 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. 
// 
// ----------------------------------------------------------------------------- 
// File: reflection.h 
// ----------------------------------------------------------------------------- 
// 
// This file defines the routines to access and operate on an Abseil Flag's 
// reflection handle. 
 
#ifndef ABSL_FLAGS_REFLECTION_H_ 
#define ABSL_FLAGS_REFLECTION_H_ 
 
#include <string> 
 
#include "absl/base/config.h" 
#include "absl/container/flat_hash_map.h" 
#include "absl/flags/commandlineflag.h" 
#include "absl/flags/internal/commandlineflag.h" 
 
namespace absl { 
ABSL_NAMESPACE_BEGIN 
namespace flags_internal { 
class FlagSaverImpl; 
}  // namespace flags_internal 
 
// FindCommandLineFlag() 
// 
// Returns the reflection handle of an Abseil flag of the specified name, or 
// `nullptr` if not found. This function will emit a warning if the name of a 
// 'retired' flag is specified. 
absl::CommandLineFlag* FindCommandLineFlag(absl::string_view name); 
 
// Returns current state of the Flags registry in a form of mapping from flag 
// name to a flag reflection handle. 
absl::flat_hash_map<absl::string_view, absl::CommandLineFlag*> GetAllFlags(); 
 
//------------------------------------------------------------------------------ 
// FlagSaver 
//------------------------------------------------------------------------------ 
// 
// A FlagSaver object stores the state of flags in the scope where the FlagSaver 
// is defined, allowing modification of those flags within that scope and 
// automatic restoration of the flags to their previous state upon leaving the 
// scope. 
// 
// A FlagSaver can be used within tests to temporarily change the test 
// environment and restore the test case to its previous state. 
// 
// Example: 
// 
//   void MyFunc() { 
//    absl::FlagSaver fs; 
//    ... 
//    absl::SetFlag(&FLAGS_myFlag, otherValue);
//    ... 
//  } // scope of FlagSaver left, flags return to previous state 
// 
// This class is thread-safe. 
 
class FlagSaver { 
 public: 
  FlagSaver(); 
  ~FlagSaver(); 
 
  FlagSaver(const FlagSaver&) = delete; 
  void operator=(const FlagSaver&) = delete; 
 
 private: 
  flags_internal::FlagSaverImpl* impl_; 
}; 
 
//----------------------------------------------------------------------------- 
 
ABSL_NAMESPACE_END 
}  // namespace absl 
 
#endif  // ABSL_FLAGS_REFLECTION_H_