mojo/public/cpp/environment/logging.h

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // Logging macros, similar to Chromium's base/logging.h, except with |MOJO_|
   6 // prefixes and missing some features (notably |CHECK_EQ()|, etc.).
   7
   8 // TODO(vtl): It's weird that this is in the environment directory, since its
   9 // implementation (in environment/lib) is meant to be used by any implementation
  10 // of the environment.
  11
  12 #ifndef MOJO_PUBLIC_CPP_ENVIRONMENT_LOGGING_H_
  13 #define MOJO_PUBLIC_CPP_ENVIRONMENT_LOGGING_H_
  14
  15 #include <sstream>
  16
  17 #include "mojo/public/c/environment/logger.h"
  18 #include "mojo/public/cpp/environment/environment.h"
  19 #include "mojo/public/cpp/system/macros.h"
  20
  21 #define MOJO_LOG_STREAM(level)                                             \
  22   ::mojo::internal::LogMessage(__FILE__, __LINE__, MOJO_LOG_LEVEL_##level) \
  23       .stream()
  24
  25 #define MOJO_LAZY_LOG_STREAM(level, condition) \
  26   !(condition) ? (void)0                       \
  27                : ::mojo::internal::VoidifyOstream() & MOJO_LOG_STREAM(level)
  28
  29 #define MOJO_SHOULD_LOG(level) \
  30   (MOJO_LOG_LEVEL_##level >=   \
  31    ::mojo::Environment::GetDefaultLogger()->GetMinimumLogLevel())
  32
  33 #define MOJO_LOG(level) MOJO_LAZY_LOG_STREAM(level, MOJO_SHOULD_LOG(level))
  34
  35 #define MOJO_LOG_IF(level, condition) \
  36   MOJO_LAZY_LOG_STREAM(level, MOJO_SHOULD_LOG(level) && (condition))
  37
  38 #define MOJO_CHECK(condition)                                                  \
  39   MOJO_LAZY_LOG_STREAM(FATAL, !(condition)) << "Check failed: " #condition "." \
  40                                                                            " "
  41
  42 // Note: For non-debug builds, |MOJO_DLOG_IF()| *eliminates* (i.e., doesn't
  43 // compile) the condition, whereas |MOJO_DCHECK()| "neuters" the condition
  44 // (i.e., compiles, but doesn't evaluate).
  45 #ifdef NDEBUG
  46
  47 #define MOJO_DLOG(level) MOJO_LAZY_LOG_STREAM(level, false)
  48 #define MOJO_DLOG_IF(level, condition) MOJO_LAZY_LOG_STREAM(level, false)
  49 #define MOJO_DCHECK(condition) \
  50     MOJO_LAZY_LOG_STREAM(FATAL, false ? !(condition) : false)
  51
  52 #else
  53
  54 #define MOJO_DLOG(level) MOJO_LOG(level)
  55 #define MOJO_DLOG_IF(level, condition) MOJO_LOG_IF(level, condition)
  56 #define MOJO_DCHECK(condition) MOJO_CHECK(condition)
  57
  58 #endif  // NDEBUG
  59
  60 namespace mojo {
  61 namespace internal {
  62
  63 class LogMessage {
  64  public:
  65   LogMessage(const char* file, int line, MojoLogLevel log_level);
  66   ~LogMessage();
  67
  68   std::ostream& stream() { return stream_; }
  69
  70  private:
  71   const MojoLogLevel log_level_;
  72   std::ostringstream stream_;
  73
  74   MOJO_DISALLOW_COPY_AND_ASSIGN(LogMessage);
  75 };
  76
  77 // Used to ignore a stream.
  78 struct VoidifyOstream {
  79   // Use & since it has precedence lower than << but higher than ?:.
  80   void operator&(std::ostream&) {}
  81 };
  82
  83 }  // namespace internal
  84 }  // namespace mojo
  85
  86 #endif  // MOJO_PUBLIC_CPP_ENVIRONMENT_LOGGING_H_