third-party/benchmark/src/log.h

   1 #ifndef BENCHMARK_LOG_H_
   2 #define BENCHMARK_LOG_H_
   3
   4 #include <iostream>
   5 #include <ostream>
   6
   7 // NOTE: this is also defined in benchmark.h but we're trying to avoid a
   8 // dependency.
   9 // The _MSVC_LANG check should detect Visual Studio 2015 Update 3 and newer.
  10 #if __cplusplus >= 201103L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201103L)
  11 #define BENCHMARK_HAS_CXX11
  12 #endif
  13
  14 namespace benchmark {
  15 namespace internal {
  16
  17 typedef std::basic_ostream<char>&(EndLType)(std::basic_ostream<char>&);
  18
  19 class LogType {
  20   friend LogType& GetNullLogInstance();
  21   friend LogType& GetErrorLogInstance();
  22
  23   // FIXME: Add locking to output.
  24   template <class Tp>
  25   friend LogType& operator<<(LogType&, Tp const&);
  26   friend LogType& operator<<(LogType&, EndLType*);
  27
  28  private:
  29   LogType(std::ostream* out) : out_(out) {}
  30   std::ostream* out_;
  31
  32   // NOTE: we could use BENCHMARK_DISALLOW_COPY_AND_ASSIGN but we shouldn't have
  33   // a dependency on benchmark.h from here.
  34 #ifndef BENCHMARK_HAS_CXX11
  35   LogType(const LogType&);
  36   LogType& operator=(const LogType&);
  37 #else
  38   LogType(const LogType&) = delete;
  39   LogType& operator=(const LogType&) = delete;
  40 #endif
  41 };
  42
  43 template <class Tp>
  44 LogType& operator<<(LogType& log, Tp const& value) {
  45   if (log.out_) {
  46     *log.out_ << value;
  47   }
  48   return log;
  49 }
  50
  51 inline LogType& operator<<(LogType& log, EndLType* m) {
  52   if (log.out_) {
  53     *log.out_ << m;
  54   }
  55   return log;
  56 }
  57
  58 inline int& LogLevel() {
  59   static int log_level = 0;
  60   return log_level;
  61 }
  62
  63 inline LogType& GetNullLogInstance() {
  64   static LogType null_log(static_cast<std::ostream*>(nullptr));
  65   return null_log;
  66 }
  67
  68 inline LogType& GetErrorLogInstance() {
  69   static LogType error_log(&std::clog);
  70   return error_log;
  71 }
  72
  73 inline LogType& GetLogInstanceForLevel(int level) {
  74   if (level <= LogLevel()) {
  75     return GetErrorLogInstance();
  76   }
  77   return GetNullLogInstance();
  78 }
  79
  80 }  // end namespace internal
  81 }  // end namespace benchmark
  82
  83 // clang-format off
  84 #define BM_VLOG(x)                                                               \
  85   (::benchmark::internal::GetLogInstanceForLevel(x) << "-- LOG(" << x << "):" \
  86                                                                          " ")
  87 // clang-format on
  88 #endif