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/* Python reference-holding class
Copyright (C) 2016 Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef GDB_PYTHON_REF_H
#define GDB_PYTHON_REF_H
/* An instance of this class either holds a reference to a PyObject,
or is "NULL". If it holds a reference, then when the object is
destroyed, the PyObject is decref'd.
Normally an instance is constructed using a PyObject*. This sort
of initialization lets this class manage the lifetime of that
reference.
Assignment and copy construction will make a new reference as
appropriate. Assignment from a plain PyObject* is disallowed to
avoid confusion about whether this acquires a new reference;
instead use the "reset" method -- which, like the PyObject*
constructor, transfers ownership.
*/
class gdbpy_ref
{
public:
/* Create a new NULL instance. */
gdbpy_ref ()
: m_obj (NULL)
{
}
/* Create a new instance. OBJ is a reference, management of which
is now transferred to this class. */
explicit gdbpy_ref (PyObject *obj)
: m_obj (obj)
{
}
/* Copy another instance. */
gdbpy_ref (const gdbpy_ref &other)
: m_obj (other.m_obj)
{
Py_XINCREF (m_obj);
}
/* Transfer ownership from OTHER. */
gdbpy_ref (gdbpy_ref &&other)
: m_obj (other.m_obj)
{
other.m_obj = NULL;
}
/* Destroy this instance. */
~gdbpy_ref ()
{
Py_XDECREF (m_obj);
}
/* Copy another instance. */
gdbpy_ref &operator= (const gdbpy_ref &other)
{
/* Do nothing on self-assignment. */
if (this != &other)
{
reset (other.m_obj);
Py_XINCREF (m_obj);
}
return *this;
}
/* Transfer ownership from OTHER. */
gdbpy_ref &operator= (gdbpy_ref &&other)
{
/* Do nothing on self-assignment. */
if (this != &other)
{
reset (other.m_obj);
other.m_obj = NULL;
}
return *this;
}
/* Change this instance's referent. OBJ is a reference, management
of which is now transferred to this class. */
void reset (PyObject *obj)
{
Py_XDECREF (m_obj);
m_obj = obj;
}
/* Return this instance's referent. In Python terms this is a
borrowed pointer. */
PyObject *get () const
{
return m_obj;
}
/* Return this instance's referent, and stop managing this
reference. The caller is now responsible for the ownership of
the reference. */
PyObject *release ()
{
PyObject *result = m_obj;
m_obj = NULL;
return result;
}
private:
PyObject *m_obj;
};
inline bool operator== (const gdbpy_ref &self, const gdbpy_ref &other)
{
return self.get () == other.get ();
}
inline bool operator== (const gdbpy_ref &self, const PyObject *other)
{
return self.get () == other;
}
inline bool operator== (const PyObject *self, const gdbpy_ref &other)
{
return self == other.get ();
}
inline bool operator!= (const gdbpy_ref &self, const gdbpy_ref &other)
{
return self.get () != other.get ();
}
inline bool operator!= (const gdbpy_ref &self, const PyObject *other)
{
return self.get () != other;
}
inline bool operator!= (const PyObject *self, const gdbpy_ref &other)
{
return self != other.get ();
}
#endif /* GDB_PYTHON_REF_H */
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