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 <stddef.h>
9
10#include <cassert>
11#include <string>
12
13#include "base/base_export.h"
14#include "base/hash.h"
15
16namespace tracked_objects {
17
18// Location provides basic info where of an object was constructed, or was
19// significantly brought to life.
20class BASE_EXPORT Location {
21 public:
22  // Constructor should be called with a long-lived char*, such as __FILE__.
23  // It assumes the provided value will persist as a global constant, and it
24  // will not make a copy of it.
25  Location(const char* function_name,
26           const char* file_name,
27           int line_number,
28           const void* program_counter);
29
30  // Provide a default constructor for easy of debugging.
31  Location();
32
33  // Copy constructor.
34  Location(const Location& other);
35
36  // Comparator for hash map insertion.
37  // No need to use |function_name_| since the other two fields uniquely
38  // identify this location.
39  bool operator==(const Location& other) const {
40    return line_number_ == other.line_number_ &&
41           file_name_ == other.file_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  // Hash operator for hash maps.
52  struct Hash {
53    size_t operator()(const Location& location) const {
54      // Compute the hash value using file name pointer and line number.
55      // No need to use |function_name_| since the other two fields uniquely
56      // identify this location.
57
58      // The file name will always be uniquely identified by its pointer since
59      // it comes from __FILE__, so no need to check the contents of the string.
60      // See the definition of FROM_HERE in location.h, and how it is used
61      // elsewhere.
62      return base::HashInts(reinterpret_cast<uintptr_t>(location.file_name()),
63                            location.line_number());
64    }
65  };
66
67  // Translate the some of the state in this instance into a human readable
68  // string with HTML characters in the function names escaped, and append that
69  // string to |output|.  Inclusion of the file_name_ and function_name_ are
70  // optional, and controlled by the boolean arguments.
71  void Write(bool display_filename, bool display_function_name,
72             std::string* output) const;
73
74  // Write function_name_ in HTML with '<' and '>' properly encoded.
75  void WriteFunctionName(std::string* output) const;
76
77 private:
78  const char* function_name_;
79  const char* file_name_;
80  int line_number_;
81  const void* program_counter_;
82};
83
84// A "snapshotted" representation of the Location class that can safely be
85// passed across process boundaries.
86struct BASE_EXPORT LocationSnapshot {
87  // The default constructor is exposed to support the IPC serialization macros.
88  LocationSnapshot();
89  explicit LocationSnapshot(const tracked_objects::Location& location);
90  ~LocationSnapshot();
91
92  std::string file_name;
93  std::string function_name;
94  int line_number;
95};
96
97BASE_EXPORT const void* GetProgramCounter();
98
99// Define a macro to record the current source location.
100#define FROM_HERE FROM_HERE_WITH_EXPLICIT_FUNCTION(__func__)
101
102#define FROM_HERE_WITH_EXPLICIT_FUNCTION(function_name)                        \
103    ::tracked_objects::Location(function_name,                                 \
104                                __FILE__,                                      \
105                                __LINE__,                                      \
106                                ::tracked_objects::GetProgramCounter())
107
108}  // namespace tracked_objects
109
110#endif  // BASE_LOCATION_H_
111