/* An arena-like memory interface for the compiler.
 */

#ifndef Py_LIMITED_API
#ifndef Py_PYARENA_H
#define Py_PYARENA_H

#ifdef __cplusplus
extern "C" {
#endif

 typedef struct _arena PyArena;

 /* PyArena_New() and PyArena_Free() create a new arena and free it,
 respectively. Once an arena has been created, it can be used
 to allocate memory via PyArena_Malloc(). Pointers to PyObject can
 also be registered with the arena via PyArena_AddPyObject(), and the
 arena will ensure that the PyObjects stay alive at least until
 PyArena_Free() is called. When an arena is freed, all the memory it
 allocated is freed, the arena releases internal references to registered
 PyObject*, and none of its pointers are valid.
 XXX (tim) What does "none of its pointers are valid" mean? Does it
 XXX mean that pointers previously obtained via PyArena_Malloc() are
 XXX no longer valid? (That's clearly true, but not sure that's what
 XXX the text is trying to say.)

 PyArena_New() returns an arena pointer. On error, it
 returns a negative number and sets an exception.
 XXX (tim): Not true. On error, PyArena_New() actually returns NULL,
 XXX and looks like it may or may not set an exception (e.g., if the
 XXX internal PyList_New(0) returns NULL, PyArena_New() passes that on
 XXX and an exception is set; OTOH, if the internal
 XXX block_new(DEFAULT_BLOCK_SIZE) returns NULL, that's passed on but
 XXX an exception is not set in that case).
 */
 PyAPI_FUNC(PyArena *) PyArena_New(void);
 PyAPI_FUNC(void) PyArena_Free(PyArena *);

 /* Mostly like malloc(), return the address of a block of memory spanning
 * `size` bytes, or return NULL (without setting an exception) if enough
 * new memory can't be obtained. Unlike malloc(0), PyArena_Malloc() with
 * size=0 does not guarantee to return a unique pointer (the pointer
 * returned may equal one or more other pointers obtained from
 * PyArena_Malloc()).
 * Note that pointers obtained via PyArena_Malloc() must never be passed to
 * the system free() or realloc(), or to any of Python's similar memory-
 * management functions. PyArena_Malloc()-obtained pointers remain valid
 * until PyArena_Free(ar) is called, at which point all pointers obtained
 * from the arena `ar` become invalid simultaneously.
 */
 PyAPI_FUNC(void *) PyArena_Malloc(PyArena *, size_t size);

 /* This routine isn't a proper arena allocation routine. It takes
 * a PyObject* and records it so that it can be DECREFed when the
 * arena is freed.
 */
 PyAPI_FUNC(int) PyArena_AddPyObject(PyArena *, PyObject *);

#ifdef __cplusplus
}
#endif

#endif /* !Py_PYARENA_H */
#endif /* Py_LIMITED_API */