| // Licensed to the Apache Software Foundation (ASF) under one |
| // or more contributor license agreements. See the NOTICE file |
| // distributed with this work for additional information |
| // regarding copyright ownership. The ASF licenses this file |
| // to you 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 |
| // |
| // http://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. |
| |
| #ifndef IMPALA_TESTUTIL_SCOPED_FLAG_SETTER_H |
| #define IMPALA_TESTUTIL_SCOPED_FLAG_SETTER_H |
| |
| namespace impala { |
| |
| /// Temporarily sets a flag for the duration of its scope, then resets the flag to its |
| /// original value upon destruction. |
| // |
| /// Example (pre-condition: FLAGS_my_string_flag == "world"): |
| /// { |
| /// auto s = ScopedFlagSetter<string>::Make(&FLAGS_my_string_flag, "hello"); |
| /// // ... FLAGS_my_string_flag == "hello" for entire scope |
| /// } |
| /// // After destruction of 's', FLAGS_my_string_flag == "world" again. |
| template <typename T> |
| struct ScopedFlagSetter { |
| static ScopedFlagSetter<T> Make(T* f, const T& new_val) { |
| return ScopedFlagSetter(f, new_val); |
| } |
| |
| ~ScopedFlagSetter() { *flag = old_val; } |
| |
| private: |
| ScopedFlagSetter(T* f, T new_val) { |
| flag = f; |
| old_val = *f; |
| *f = new_val; |
| } |
| |
| T* flag; |
| T old_val; |
| }; |
| } |
| |
| #endif |