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 // Copyright (c) 2012 The Chromium Authors. All rights reserved.

 // Use of this source code is governed by a BSD-style license that can be

 // found in the LICENSE file.

 #ifndef BASE_LOCATION_H_

 #define BASE_LOCATION_H_

 #include <string>

 #include "base/base_export.h"

 #include "base/basictypes.h"

 namespace tracked_objects {

 // Location provides basic info where of an object was constructed, or was

 // significantly brought to life.

 class BASE_EXPORT Location {

  public:

   // Constructor should be called with a long-lived char*, such as __FILE__.

   // It assumes the provided value will persist as a global constant, and it

   // will not make a copy of it.

   Location(const char* function_name,

            const char* file_name,

            int line_number,

            const void* program_counter);

   // Provide a default constructor for easy of debugging.

   Location();

   // Comparison operator for insertion into a std::map<> hash tables.

   // All we need is *some* (any) hashing distinction.  Strings should already

   // be unique, so we don't bother with strcmp or such.

   // Use line number as the primary key (because it is fast, and usually gets us

   // a difference), and then pointers as secondary keys (just to get some

   // distinctions).

   bool operator < (const Location& other) const {

     if (line_number_ != other.line_number_)

       return line_number_ < other.line_number_;

     if (file_name_ != other.file_name_)

       return file_name_ < other.file_name_;

     return function_name_ < other.function_name_;

   }

   const char* function_name()   const { return function_name_; }

   const char* file_name()       const { return file_name_; }

   int line_number()             const { return line_number_; }

   const void* program_counter() const { return program_counter_; }

   std::string ToString() const;

   // Translate the some of the state in this instance into a human readable

   // string with HTML characters in the function names escaped, and append that

   // string to |output|.  Inclusion of the file_name_ and function_name_ are

   // optional, and controlled by the boolean arguments.

   void Write(bool display_filename, bool display_function_name,

              std::string* output) const;

   // Write function_name_ in HTML with '<' and '>' properly encoded.

   void WriteFunctionName(std::string* output) const;

  private:

   const char* function_name_;

   const char* file_name_;

   int line_number_;

   const void* program_counter_;

 };

 // A "snapshotted" representation of the Location class that can safely be

 // passed across process boundaries.

 struct BASE_EXPORT LocationSnapshot {

   // The default constructor is exposed to support the IPC serialization macros.

   LocationSnapshot();

   explicit LocationSnapshot(const tracked_objects::Location& location);

   ~LocationSnapshot();

   std::string file_name;

   std::string function_name;

   int line_number;

 };

 BASE_EXPORT const void* GetProgramCounter();

 // Define a macro to record the current source location.

 #define FROM_HERE FROM_HERE_WITH_EXPLICIT_FUNCTION(__FUNCTION__)

 #define FROM_HERE_WITH_EXPLICIT_FUNCTION(function_name)                        \

     ::tracked_objects::Location(function_name,                                 \

                                 __FILE__,                                      \

                                 __LINE__,                                      \

                                 ::tracked_objects::GetProgramCounter())

 }  // namespace tracked_objects

 #endif  // BASE_LOCATION_H_