00001 /* 00002 * Copyright 2018 The Cartographer Authors 00003 * 00004 * Licensed under the Apache License, Version 2.0 (the "License"); 00005 * you may not use this file except in compliance with the License. 00006 * You may obtain a copy of the License at 00007 * 00008 * http://www.apache.org/licenses/LICENSE-2.0 00009 * 00010 * Unless required by applicable law or agreed to in writing, software 00011 * distributed under the License is distributed on an "AS IS" BASIS, 00012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 00013 * See the License for the specific language governing permissions and 00014 * limitations under the License. 00015 */ 00016 00017 #include "cartographer/metrics/counter.h" 00018 00019 namespace cartographer { 00020 namespace metrics { 00021 00022 namespace { 00023 00024 // Implementation of counter that does nothing. 00025 class NullCounter : public Counter { 00026 public: 00027 void Increment() override{}; 00028 void Increment(double) override{}; 00029 }; 00030 00031 } // namespace 00032 00033 Counter* Counter::Null() { 00034 static NullCounter null_counter; 00035 return &null_counter; 00036 } 00037 00038 } // namespace metrics 00039 } // namespace cartographer