/* An arena-like memory interface for the compiler. */ #ifndef Py_PYARENA_H#define Py_PYARENA_H #ifdef __cplusplusextern "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  Does it     XXX mean that pointers previously obtained via PyArena_Malloc() are     XXX no longer valid?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 */