gdbsupport/refcounted-object.h

   1 /* Base class of intrusively reference-counted objects.
   2    Copyright (C) 2017-2024 Free Software Foundation, Inc.
   3
   4    This file is part of GDB.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 3 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  18
  19 #ifndef COMMON_REFCOUNTED_OBJECT_H
  20 #define COMMON_REFCOUNTED_OBJECT_H
  21
  22 /* Base class of intrusively reference-countable objects.
  23    Incrementing and decrementing the reference count is an external
  24    responsibility.  */
  25
  26 class refcounted_object
  27 {
  28 public:
  29   refcounted_object () = default;
  30
  31   /* Increase the refcount.  */
  32   void incref ()
  33   {
  34     gdb_assert (m_refcount >= 0);
  35     m_refcount++;
  36   }
  37
  38   /* Decrease the refcount.  */
  39   void decref ()
  40   {
  41     m_refcount--;
  42     gdb_assert (m_refcount >= 0);
  43   }
  44
  45   int refcount () const { return m_refcount; }
  46
  47 private:
  48   DISABLE_COPY_AND_ASSIGN (refcounted_object);
  49
  50   /* The reference count.  */
  51   int m_refcount = 0;
  52 };
  53
  54 /* A policy class to interface gdb::ref_ptr with a
  55    refcounted_object.  */
  56
  57 struct refcounted_object_ref_policy
  58 {
  59   static void incref (refcounted_object *ptr)
  60   {
  61     ptr->incref ();
  62   }
  63
  64   static void decref (refcounted_object *ptr)
  65   {
  66     ptr->decref ();
  67   }
  68 };
  69
  70 /* A policy class to interface gdb::ref_ptr with a refcounted_object, that
  71    deletes the object once the refcount reaches 0..  */
  72
  73 template<typename T>
  74 struct refcounted_object_delete_ref_policy
  75 {
  76   static void incref (T *obj)
  77   { obj->incref (); }
  78
  79   static void decref (T *obj)
  80   {
  81     obj->decref ();
  82     if (obj->refcount () == 0)
  83       delete obj;
  84   }
  85 };
  86
  87 #endif /* COMMON_REFCOUNTED_OBJECT_H */