base/location.h

   1 // Copyright (c) 2012 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 #ifndef BASE_LOCATION_H_
   6 #define BASE_LOCATION_H_
   7
   8 #include <string>
   9
  10 #include "base/base_export.h"
  11 #include "base/basictypes.h"
  12
  13 namespace tracked_objects {
  14
  15 // Location provides basic info where of an object was constructed, or was
  16 // significantly brought to life.
  17 class BASE_EXPORT Location {
  18  public:
  19   // Constructor should be called with a long-lived char*, such as __FILE__.
  20   // It assumes the provided value will persist as a global constant, and it
  21   // will not make a copy of it.
  22   Location(const char* function_name,
  23            const char* file_name,
  24            int line_number,
  25            const void* program_counter);
  26
  27   // Provide a default constructor for easy of debugging.
  28   Location();
  29
  30   // Comparison operator for insertion into a std::map<> hash tables.
  31   // All we need is *some* (any) hashing distinction.  Strings should already
  32   // be unique, so we don't bother with strcmp or such.
  33   // Use line number as the primary key (because it is fast, and usually gets us
  34   // a difference), and then pointers as secondary keys (just to get some
  35   // distinctions).
  36   bool operator < (const Location& other) const {
  37     if (line_number_ != other.line_number_)
  38       return line_number_ < other.line_number_;
  39     if (file_name_ != other.file_name_)
  40       return file_name_ < other.file_name_;
  41     return function_name_ < other.function_name_;
  42   }
  43
  44   const char* function_name()   const { return function_name_; }
  45   const char* file_name()       const { return file_name_; }
  46   int line_number()             const { return line_number_; }
  47   const void* program_counter() const { return program_counter_; }
  48
  49   std::string ToString() const;
  50
  51   // Translate the some of the state in this instance into a human readable
  52   // string with HTML characters in the function names escaped, and append that
  53   // string to |output|.  Inclusion of the file_name_ and function_name_ are
  54   // optional, and controlled by the boolean arguments.
  55   void Write(bool display_filename, bool display_function_name,
  56              std::string* output) const;
  57
  58   // Write function_name_ in HTML with '<' and '>' properly encoded.
  59   void WriteFunctionName(std::string* output) const;
  60
  61  private:
  62   const char* function_name_;
  63   const char* file_name_;
  64   int line_number_;
  65   const void* program_counter_;
  66 };
  67
  68 // A "snapshotted" representation of the Location class that can safely be
  69 // passed across process boundaries.
  70 struct BASE_EXPORT LocationSnapshot {
  71   // The default constructor is exposed to support the IPC serialization macros.
  72   LocationSnapshot();
  73   explicit LocationSnapshot(const tracked_objects::Location& location);
  74   ~LocationSnapshot();
  75
  76   std::string file_name;
  77   std::string function_name;
  78   int line_number;
  79 };
  80
  81 BASE_EXPORT const void* GetProgramCounter();
  82
  83 // Define a macro to record the current source location.
  84 #define FROM_HERE FROM_HERE_WITH_EXPLICIT_FUNCTION(__FUNCTION__)
  85
  86 #define FROM_HERE_WITH_EXPLICIT_FUNCTION(function_name)                        \
  87     ::tracked_objects::Location(function_name,                                 \
  88                                 __FILE__,                                      \
  89                                 __LINE__,                                      \
  90                                 ::tracked_objects::GetProgramCounter())
  91
  92 }  // namespace tracked_objects
  93
  94 #endif  // BASE_LOCATION_H_