chore: import upstream snapshot with attribution

src/butil/location.h

@@ -0,0 +1,94 @@
+// 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 BUTIL_LOCATION_H_
+#define BUTIL_LOCATION_H_
+
+#include <string>
+
+#include "butil/base_export.h"
+#include "butil/basictypes.h"
+
+namespace tracked_objects {
+
+// Location provides basic info where of an object was constructed, or was
+// significantly brought to life.
+class BUTIL_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 BUTIL_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;
+};
+
+BUTIL_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  // BUTIL_LOCATION_H_