/* vim:set noet ts=8 sw=8 : */
#include "greenlet.h"
#include "structmember.h"


/* XXX major open bugs:
   XXX - no GC.  Unfinished greenlets won't be deallocated if they
   XXX   contain a cycle to themselves from anywhere in their frame stack.
*/

/***********************************************************

A PyGreenlet is a range of C stack addresses that must be
saved and restored in such a way that the full range of the
stack contains valid data when we switch to it.

Stack layout for a greenlet:

               |     ^^^       |
               |  older data   |
               |               |
  stack_stop . |_______________|
        .      |               |
        .      | greenlet data |
        .      |   in stack    |
        .    * |_______________| . .  _____________  stack_copy + stack_saved
        .      |               |     |             |
        .      |     data      |     |greenlet data|
        .      |   unrelated   |     |    saved    |
        .      |      to       |     |   in heap   |
 stack_start . |     this      | . . |_____________| stack_copy
               |   greenlet    |
               |               |
               |  newer data   |
               |     vvv       |


Note that a greenlet's stack data is typically partly at its correct
place in the stack, and partly saved away in the heap, but always in
the above configuration: two blocks, the more recent one in the heap
and the older one still in the stack (either block may be empty).

Greenlets are chained: each points to the previous greenlet, which is
the one that owns the data currently in the C stack above my
stack_stop.  The currently running greenlet is the first element of
this chain.  The main (initial) greenlet is the last one.  Greenlets
whose stack is entirely in the heap can be skipped from the chain.

The chain is not related to execution order, but only to the order
in which bits of C stack happen to belong to greenlets at a particular
point in time.

The main greenlet doesn't have a stack_stop: it is responsible for the
complete rest of the C stack, and we don't know where it begins.  We
use (char*) -1, the largest possible address.

States:
  stack_stop == NULL && stack_start == NULL:  did not start yet
  stack_stop != NULL && stack_start == NULL:  already finished
  stack_stop != NULL && stack_start != NULL:  active

The running greenlet's stack_start is undefined but not NULL.

 ***********************************************************/

/*** global state ***/

/* In the presence of multithreading, this is a bit tricky:

   - ts_current always store a reference to a greenlet, but it is
     not really the current greenlet after a thread switch occurred.

   - each *running* greenlet uses its run_info field to know which
     thread it is attached to.  A greenlet can only run in the thread
     where it was created.  This run_info is a ref to tstate->dict.

   - the thread state dict is used to save and restore ts_current,
     using the dictionary key 'ts_curkey'.
*/

/* Python 2.3 support */
#ifndef Py_VISIT
#define Py_VISIT(o) if (o) {if ((err = visit((PyObject *)(o), arg))) return err;}
#endif /* !Py_VISIT */

#ifndef Py_CLEAR
#define Py_CLEAR(op) \
	do { \
		if (op) { \
			PyObject *tmp = (PyObject *)(op); \
			(op) = NULL; \
			Py_DECREF(tmp); \
		} \
	} while (0)
#endif /* !Py_CLEAR */

/* The current greenlet in this thread state (holds a reference) */
static PyGreenlet* ts_current;
/* Holds a reference to the switching-from stack during the slp switch */
static PyGreenlet* ts_origin;
/* Holds a reference to the switching-to stack during the slp switch */
static PyGreenlet* ts_target;
/* NULL if error, otherwise args tuple to pass around during slp switch */
static PyObject* ts_passaround;

/***********************************************************/
/* Thread-aware routines, switching global variables when needed */

#define STATE_OK    (ts_current->run_info == PyThreadState_GET()->dict \
			|| !green_updatecurrent())

static PyObject* ts_curkey;
static PyObject* ts_delkey;
static PyObject* PyExc_GreenletError;
static PyObject* PyExc_GreenletExit;

#undef GREENLET_USE_GC

#ifdef GREENLET_USE_GC
#define GREENLET_GC_FLAGS Py_TPFLAGS_HAVE_GC
#define GREENLET_tp_alloc PyType_GenericAlloc
#define GREENLET_tp_free PyObject_GC_Del
#define GREENLET_tp_traverse green_traverse
#define GREENLET_tp_clear green_clear
#define GREENLET_tp_is_gc green_is_gc
#else /* GREENLET_USE_GC */
#define GREENLET_GC_FLAGS 0
#define GREENLET_tp_alloc 0
#define GREENLET_tp_free 0
#define GREENLET_tp_traverse 0
#define GREENLET_tp_clear 0
#define GREENLET_tp_is_gc 0
#endif /* !GREENLET_USE_GC */

static PyGreenlet* green_create_main(void)
{
	PyGreenlet* gmain;
	PyObject* dict = PyThreadState_GetDict();
	if (dict == NULL) {
		if (!PyErr_Occurred())
			PyErr_NoMemory();
		return NULL;
	}

	/* create the main greenlet for this thread */
	gmain = (PyGreenlet*) PyType_GenericAlloc(&PyGreen_Type, 0);
	if (gmain == NULL)
		return NULL;
	gmain->stack_start = (char*) 1;
	gmain->stack_stop = (char*) -1;
	gmain->run_info = dict;
	Py_INCREF(dict);
#ifdef GREENLET_USE_GC
	printf("green_create_main %p\n", gmain);
#endif
	return gmain;
}

static int green_updatecurrent(void)
{
	PyThreadState* tstate;
	PyGreenlet* next;
	PyGreenlet* previous;
	PyObject* deleteme;

	/* save ts_current as the current greenlet of its own thread */
	previous = ts_current;
	if (PyDict_SetItem(previous->run_info, ts_curkey, (PyObject*) previous))
		return -1;

	/* get ts_current from the active tstate */
	tstate = PyThreadState_GET();
	if (tstate->dict && (next =
	    (PyGreenlet*) PyDict_GetItem(tstate->dict, ts_curkey))) {
		/* found -- remove it, to avoid keeping a ref */
		Py_INCREF(next);
		if (PyDict_SetItem(tstate->dict, ts_curkey, Py_None))
			PyErr_Clear();
	}
	else {
		/* first time we see this tstate */
		next = green_create_main();
		if (next == NULL)
			return -1;
	}
	ts_current = next;
	Py_DECREF(previous);
	/* green_dealloc() cannot delete greenlets from other threads, so
	   it stores them in the thread dict; delete them now. */
	deleteme = PyDict_GetItem(tstate->dict, ts_delkey);
	if (deleteme != NULL) {
		PyList_SetSlice(deleteme, 0, INT_MAX, NULL);
	}
	return 0;
}

static PyObject* green_statedict(PyGreenlet* g)
{
	while (!PyGreen_STARTED(g))
		g = g->parent;
	return g->run_info;
}

/***********************************************************/

static int g_save(PyGreenlet* g, char* stop)
{
	/* Save more of g's stack into the heap -- at least up to 'stop'

	   g->stack_stop |________|
	                 |        |
			 |    __ stop       . . . . .
	                 |        |    ==>  .       .
			 |________|          _______
			 |        |         |       |
			 |        |         |       |
	  g->stack_start |        |         |_______| g->stack_copy

	 */
	long sz1 = g->stack_saved;
	long sz2 = stop - g->stack_start;
	if (sz2 > sz1) {
		char* c = PyMem_Realloc(g->stack_copy, sz2);
		if (!c) {
			PyErr_NoMemory();
			return -1;
		}
		memcpy(c+sz1, g->stack_start+sz1, sz2-sz1);
		g->stack_copy = c;
		g->stack_saved = sz2;
	}
	return 0;
}

static void slp_restore_state(void)
{
	PyGreenlet* g = ts_target;
	
	/* Restore the heap copy back into the C stack */
	if (g->stack_saved != 0) {
		memcpy(g->stack_start, g->stack_copy, g->stack_saved);
		PyMem_Free(g->stack_copy);
		g->stack_copy = NULL;
		g->stack_saved = 0;
	}
	if (ts_current->stack_stop == g->stack_stop)
		g->stack_prev = ts_current->stack_prev;
	else
		g->stack_prev = ts_current;
}

static int slp_save_state(char* stackref)
{
	/* must free all the C stack up to target_stop */
	char* target_stop = ts_target->stack_stop;
	assert(ts_current->stack_saved == 0);
	if (ts_current->stack_start == NULL)
		ts_current = ts_current->stack_prev;  /* not saved if dying */
	else
		ts_current->stack_start = stackref;
	
	while (ts_current->stack_stop < target_stop) {
		/* ts_current is entierely within the area to free */
		if (g_save(ts_current, ts_current->stack_stop))
			return -1;  /* XXX */
		ts_current = ts_current->stack_prev;
	}
	if (ts_current != ts_target) {
		if (g_save(ts_current, target_stop))
			return -1;  /* XXX */
	}
	return 0;
}


/*
 * the following macros are spliced into the OS/compiler
 * specific code, in order to simplify maintenance.
 */

#define SLP_SAVE_STATE(stackref, stsizediff)		\
  stackref += STACK_MAGIC;				\
  if (slp_save_state((char*)stackref)) return -1;	\
  if (!PyGreen_ACTIVE(ts_target)) return 1;		\
  stsizediff = ts_target->stack_start - (char*)stackref

#define SLP_RESTORE_STATE()			\
  slp_restore_state()


#define SLP_EVAL
#include "slp_platformselect.h"

#ifndef STACK_MAGIC
#error "greenlet needs to be ported to this platform,\
 or teached how to detect your compiler properly."
#endif /* !STACK_MAGIC */


/* This is a trick to prevent the compiler from inlining or
   removing the frames */
int (*_PyGreen_slp_switch) (void);
int (*_PyGreen_switchstack) (void);
void (*_PyGreen_initialstub) (void*);

static int g_switchstack(void)
{
	/* perform a stack switch according to some global variables
	   that must be set before:
	   - ts_current: current greenlet (holds a reference)
	   - ts_target: greenlet to switch to
	   - ts_passaround: NULL if PyErr_Occurred(),
	             else a tuple of args sent to ts_target (holds a reference)
	*/
	int err;
	{   /* save state */
		PyThreadState* tstate = PyThreadState_GET();
		ts_current->recursion_depth = tstate->recursion_depth;
		ts_current->top_frame = tstate->frame;
	}
	ts_origin = ts_current;
	err = _PyGreen_slp_switch();
	if (err < 0) {   /* error */
		Py_XDECREF(ts_passaround);
		ts_passaround = NULL;
	}
	else {
		PyThreadState* tstate = PyThreadState_GET();
		tstate->recursion_depth = ts_target->recursion_depth;
		tstate->frame = ts_target->top_frame;
		ts_target->top_frame = NULL;
		ts_current = ts_target;
		Py_INCREF(ts_target);
		Py_DECREF(ts_origin);
	}
	return err;
}

static PyObject* g_switch(PyGreenlet* target, PyObject* args)
{
	/* _consumes_ a reference to the args tuple,
	   and return a new tuple reference */

	/* check ts_current */
	if (!STATE_OK) {
		Py_DECREF(args);
		return NULL;
	}
	if (green_statedict(target) != ts_current->run_info) {
		PyErr_SetString(PyExc_GreenletError,
				"cannot switch to a different thread");
		Py_DECREF(args);
		return NULL;
	}
	ts_passaround = args;

	/* find the real target by ignoring dead greenlets,
	   and if necessary starting a greenlet. */
	while (1) {
		if (PyGreen_ACTIVE(target)) {
			ts_target = target;
			_PyGreen_switchstack();
			return ts_passaround;
		}
		if (!PyGreen_STARTED(target)) {
			void* dummymarker;
			ts_target = target;
			_PyGreen_initialstub(&dummymarker);
			return ts_passaround;
		}
		target = target->parent;
	}
}

static void g_initialstub(void* mark)
{
	int err;
	PyObject* o;

	/* ts_target.run is the object to call in the new greenlet */
	PyObject* run = PyObject_GetAttrString((PyObject*) ts_target, "run");
	if (run == NULL) {
		Py_XDECREF(ts_passaround);
		ts_passaround = NULL;
		return;
	}
	/* now use run_info to store the statedict */
	o = ts_target->run_info;
	ts_target->run_info = green_statedict(ts_target->parent);
	Py_INCREF(ts_target->run_info);
	Py_XDECREF(o);

	/* start the greenlet */
	ts_target->stack_start = NULL;
	ts_target->stack_stop = (char*) mark;
	ts_target->stack_prev = ts_current;
	ts_target->top_frame = NULL;
	ts_target->recursion_depth = PyThreadState_GET()->recursion_depth;
	err = _PyGreen_switchstack();
	/* returns twice!
	   The 1st time with err=1: we are in the new greenlet
	   The 2nd time with err=0: back in the caller's greenlet
	*/
	if (err == 1) {
		/* in the new greenlet */
		PyObject* args;
		PyObject* result;
		ts_current->stack_start = (char*) 1;  /* running */

		args = ts_passaround;
		if (args == NULL)    /* pending exception */
			result = NULL;
		else {
			/* call g.run(*args) */
			result = PyEval_CallObject(run, args);
			Py_DECREF(args);
		}
		Py_DECREF(run);
		if (result == NULL &&
		    PyErr_ExceptionMatches(PyExc_GreenletExit)) {
			/* catch and ignore GreenletExit */
			PyObject *exc, *val, *tb;
			PyErr_Fetch(&exc, &val, &tb);
			if (val == NULL) {
				Py_INCREF(Py_None);
				val = Py_None;
			}
			result = val;
			Py_DECREF(exc);
			Py_XDECREF(tb);
		}
		if (result != NULL) {
			/* package the result into a 1-tuple */
			PyObject* r = result;
			result = PyTuple_New(1);
			if (result)
				PyTuple_SET_ITEM(result, 0, r);
			else
				Py_DECREF(r);
		}
		/* jump back to parent */
		ts_current->stack_start = NULL;  /* dead */
		g_switch(ts_current->parent, result);
		/* must not return from here! */
		Py_FatalError("XXX memory exhausted at a very bad moment");
	}
	/* back in the parent */
}


/***********************************************************/


static PyObject* green_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	PyObject* o;
	if (!STATE_OK)
		return NULL;
	
	o = type->tp_alloc(type, 0);
	if (o != NULL) {
		Py_INCREF(ts_current);
		((PyGreenlet*) o)->parent = ts_current;
	}
#ifdef GREENLET_USE_GC
	printf("green_new %p\n", o);
#endif
	return o;
}

static int green_setrun(PyGreenlet* self, PyObject* nparent, void* c);
static int green_setparent(PyGreenlet* self, PyObject* nparent, void* c);

static int green_init(PyGreenlet *self, PyObject *args, PyObject *kwds)
{
	PyObject *run = NULL;
	PyObject* nparent = NULL;
	static char *kwlist[] = {"run", "parent", 0};
	if (!PyArg_ParseTupleAndKeywords(args, kwds, "|OO:green", kwlist,
					 &run, &nparent))
		return -1;

	if (run != NULL) {
		if (green_setrun(self, run, NULL))
			return -1;
	}
	if (nparent != NULL)
		return green_setparent(self, nparent, NULL);
	return 0;
}

static int kill_greenlet(PyGreenlet* self)
{
	/* Cannot raise an exception to kill the greenlet if
	   it is not running in the same thread! */
#ifdef GREENLET_USE_GC
	printf("kill_greenlet %p\n", self);
#endif
	if (self->run_info == PyThreadState_GET()->dict) {
		/* The dying greenlet cannot be a parent of ts_current
		   because the 'parent' field chain would hold a
		   reference */
		PyObject* result;
		Py_INCREF(ts_current);
		self->parent = ts_current;
		/* Send the greenlet a GreenletExit exception. */
		PyErr_SetNone(PyExc_GreenletExit);
		result = g_switch(self, NULL);
		if (result == NULL)
			return -1;
		Py_DECREF(result);
		return 0;
	}
	else {
		/* Not the same thread! Temporarily save the greenlet
		   into its thread's ts_delkey list. */
		PyObject* lst;
		lst = PyDict_GetItem(self->run_info, ts_delkey);
		if (lst == NULL) {
			lst = PyList_New(0);
			if (lst == NULL || PyDict_SetItem(self->run_info,
							  ts_delkey, lst) < 0)
				return -1;
		}
		if (PyList_Append(lst, (PyObject*) self) < 0)
			return -1;
		if (!STATE_OK)  /* to force ts_delkey to be reconsidered */
			return -1;
		return 0;
	}
}

#ifdef GREENLET_USE_GC
static int
green_traverse(PyGreenlet *so, visitproc visit, void *arg)
{
	printf("green_traverse %p\n", so);
	Py_VISIT((PyObject*)so->run_info);
	Py_VISIT((PyObject*)so->parent);
	Py_VISIT((PyObject*)so->top_frame);
	Py_VISIT((PyObject*)so->stack_prev);
	Py_VISIT((PyObject*)so->parent);
	return 0;
}

static int green_is_gc(PyGreenlet* self)
{
	int rval;
	rval = (self->stack_stop == ((char *)-1)) ? 0 : 1;
	printf("green_is_gc %p = %d\n", self, rval);
	return rval;
}

static int green_clear(PyGreenlet* self)
{
	printf("green_clear %p run_info %p\n", self, self->run_info);
	if (PyGreen_ACTIVE(self))
		return kill_greenlet(self);
	return 0;
}
#endif

static void green_dealloc(PyGreenlet* self)
{
	PyObject *error_type, *error_value, *error_traceback;

#ifdef GREENLET_USE_GC
	printf("green_dealloc %p\n", self);
	PyObject_GC_UnTrack((PyObject *)self);
	Py_TRASHCAN_SAFE_BEGIN(self);
#endif /* GREENLET_USE_GC */
	Py_CLEAR(self->parent);
	if (PyGreen_ACTIVE(self)) {
		/* Hacks hacks hacks copied from instance_dealloc() */
		/* Temporarily resurrect the greenlet. */
		assert(self->ob_refcnt == 0);
		self->ob_refcnt = 1;
		/* Save the current exception, if any. */
		PyErr_Fetch(&error_type, &error_value, &error_traceback);
		if (kill_greenlet(self) < 0) {
			PyErr_WriteUnraisable((PyObject*) self);
			/* XXX what else should we do? */
		}
		/* Restore the saved exception. */
		PyErr_Restore(error_type, error_value, error_traceback);
		/* Undo the temporary resurrection; can't use DECREF here,
		 * it would cause a recursive call.
		 */
		assert(self->ob_refcnt > 0);
		--self->ob_refcnt;
		if (self->ob_refcnt == 0 && PyGreen_ACTIVE(self)) {
			/* Not resurrected, but still not dead!
			   XXX what else should we do? we complain. */
			PyObject* f = PySys_GetObject("stderr");
			if (f != NULL) {
				PyFile_WriteString("GreenletExit did not kill ",
						   f);
				PyFile_WriteObject((PyObject*) self, f, 0);
				PyFile_WriteString("\n", f);
			}
			Py_INCREF(self);   /* leak! */
		}
		if (self->ob_refcnt != 0) {
			/* Resurrected! */
			int refcnt = self->ob_refcnt;
			_Py_NewReference((PyObject*) self);
#ifdef GREENLET_USE_GC
			PyObject_GC_Track((PyObject *)self);
#endif
			self->ob_refcnt = refcnt;
#ifdef COUNT_ALLOCS
			--self->ob_type->tp_frees;
			--self->ob_type->tp_allocs;
#endif /* COUNT_ALLOCS */
			goto green_dealloc_end;
		}
	}
	if (self->weakreflist != NULL)
		PyObject_ClearWeakRefs((PyObject *) self);
	Py_CLEAR(self->run_info);
	self->ob_type->tp_free((PyObject*) self);
green_dealloc_end:
#ifdef GREENLET_USE_GC
	Py_TRASHCAN_SAFE_END(self);
#endif /* GREENLET_USE_GC */
	return;
}

static PyObject* single_result(PyObject* results)
{
	if (results != NULL && PyTuple_Check(results) &&
	    PyTuple_GET_SIZE(results) == 1) {
		PyObject *result = PyTuple_GET_ITEM(results, 0);
		Py_INCREF(result);
		Py_DECREF(results);
		return result;
	}
	else
		return results;
}

PyDoc_STRVAR(green_switch_doc,
"switch(*args)\n\
\n\
Switch execution to this greenlet.\n\
\n\
If this greenlet has never been run, then this greenlet\n\
will be switched to using the body of self.run(*args).\n\
\n\
If the greenlet is active (has been run, but was switch()'ed\n\
out before leaving its run function), then this greenlet will\n\
be resumed and the return value to its switch call will be\n\
None if no arguments are given, the given argument if one\n\
argument is given, or the args tuple if multiple arguments\n\
are given\n\
\n\
If the greenlet is dead, or is the current greenlet then this\n\
function will simply return the args using the same rules as\n\
above.");

static PyObject* green_switch(PyGreenlet* self, PyObject* args)
{
	Py_INCREF(args);
	return single_result(g_switch(self, args));
}

static int green_nonzero(PyGreenlet* self)
{
	return PyGreen_ACTIVE(self);
}

static PyObject* green_getdead(PyGreenlet* self, void* c)
{
	PyObject* res;
	if (PyGreen_ACTIVE(self) || !PyGreen_STARTED(self))
		res = Py_False;
	else
		res = Py_True;
	Py_INCREF(res);
	return res;
}

static PyObject* green_getrun(PyGreenlet* self, void* c)
{
	if (PyGreen_STARTED(self) || self->run_info == NULL) {
		PyErr_SetString(PyExc_AttributeError, "run");
		return NULL;
	}
	Py_INCREF(self->run_info);
	return self->run_info;
}

static int green_setrun(PyGreenlet* self, PyObject* nrun, void* c)
{
	PyObject* o;
	if (PyGreen_STARTED(self)) {
		PyErr_SetString(PyExc_AttributeError,
				"run cannot be set "
				"after the start of the greenlet");
		return -1;
	}
	o = self->run_info;
	self->run_info = nrun;
	Py_XINCREF(nrun);
	Py_XDECREF(o);
	return 0;
}

static PyObject* green_getparent(PyGreenlet* self, void* c)
{
	PyObject* result = self->parent ? (PyObject*) self->parent : Py_None;
	Py_INCREF(result);
	return result;
}

static int green_setparent(PyGreenlet* self, PyObject* nparent, void* c)
{
	PyGreenlet* p;
	if (nparent == NULL) {
		PyErr_SetString(PyExc_AttributeError, "can't delete attribute");
		return -1;
	}
	if (!PyGreen_Check(nparent)) {
		PyErr_SetString(PyExc_TypeError, "parent must be a greenlet");
		return -1;
	}
	for (p=(PyGreenlet*) nparent; p; p=p->parent) {
		if (p == self) {
			PyErr_SetString(PyExc_ValueError, "cyclic parent chain");
			return -1;
		}
	}
	p = self->parent;
	self->parent = (PyGreenlet*) nparent;
	Py_INCREF(nparent);
	Py_DECREF(p);
	return 0;
}

static PyObject* green_getframe(PyGreenlet* self, void* c)
{
	PyObject* result = self->top_frame ? (PyObject*) self->top_frame : Py_None;
	Py_INCREF(result);
	return result;
}


/***********************************************************/
/* C interface */

PyObject* PyGreen_New(PyObject* run, PyObject* parent)
{
	PyGreenlet* o;
	if (!PyGreen_Check(parent)) {
		PyErr_SetString(PyExc_TypeError, "parent must be a greenlet");
		return NULL;
	}
	o = (PyGreenlet*) PyType_GenericAlloc(&PyGreen_Type, 0);
	if (o == NULL)
		return NULL;
	Py_INCREF(run);
	o->run_info = run;
	Py_INCREF(parent);
	o->parent = (PyGreenlet*) parent;
	return (PyObject*) o;
}

PyObject* PyGreen_Current(void)
{
	if (!STATE_OK)
		return NULL;
	return (PyObject*) ts_current;
}

PyObject* PyGreen_Switch(PyObject* g, PyObject* value)
{
	if (!PyGreen_Check(g)) {
		PyErr_BadInternalCall();
		return NULL;
	}
	Py_XINCREF(value);
	return single_result(g_switch((PyGreenlet*) g, value));
}

int PyGreen_SetParent(PyObject* g, PyObject* nparent)
{
	if (!PyGreen_Check(g)) {
		PyErr_BadInternalCall();
		return -1;
	}
	return green_setparent((PyGreenlet*) g, nparent, NULL);
}

/***********************************************************/


static PyMethodDef green_methods[] = {
    {"switch", (PyCFunction)green_switch, METH_VARARGS, green_switch_doc},
    {NULL,     NULL}		/* sentinel */
};

static PyGetSetDef green_getsets[] = {
	{"run",    (getter)green_getrun,
		   (setter)green_setrun, /*XXX*/ NULL},
	{"parent", (getter)green_getparent,
		   (setter)green_setparent, /*XXX*/ NULL},
	{"gr_frame", (getter)green_getframe,
	             NULL, /*XXX*/ NULL},
	{"dead",   (getter)green_getdead,
	             NULL, /*XXX*/ NULL},
	{NULL}
};

static PyNumberMethods green_as_number = {
	NULL,		/* nb_add */
	NULL,		/* nb_subtract */
	NULL,		/* nb_multiply */
	NULL,		/* nb_divide */
	NULL,		/* nb_remainder */
	NULL,		/* nb_divmod */
	NULL,		/* nb_power */
	NULL,		/* nb_negative */
	NULL,		/* nb_positive */
	NULL,		/* nb_absolute */
	(inquiry)green_nonzero,	/* nb_nonzero */
};

PyTypeObject PyGreen_Type = {
	PyObject_HEAD_INIT(NULL)
	0,					/* ob_size */
	"greenlet.greenlet",			/* tp_name */
	sizeof(PyGreenlet),			/* tp_basicsize */
	0,					/* tp_itemsize */
	/* methods */
	(destructor)green_dealloc,		/* tp_dealloc */
	0,					/* tp_print */
	0,					/* tp_getattr */
	0,					/* tp_setattr */
	0,					/* tp_compare */
	0,					/* tp_repr */
	&green_as_number,			/* tp_as _number*/
	0,					/* tp_as _sequence*/
	0,					/* tp_as _mapping*/
	0, 					/* tp_hash */
	0,					/* tp_call */
	0,					/* tp_str */
	0,					/* tp_getattro */
	0,					/* tp_setattro */
	0,					/* tp_as_buffer*/
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | GREENLET_GC_FLAGS,	/* tp_flags */
	0,					/* tp_doc */
	(traverseproc)GREENLET_tp_traverse,	/* tp_traverse */
	(inquiry)GREENLET_tp_clear,		/* tp_clear */
	0,					/* tp_richcompare */
	offsetof(PyGreenlet, weakreflist),	/* tp_weaklistoffset */
	0,					/* tp_iter */
	0,					/* tp_iternext */
	green_methods,				/* tp_methods */
	0,					/* tp_members */
	green_getsets,				/* tp_getset */
	0,					/* tp_base */
	0,					/* tp_dict */
	0,					/* tp_descr_get */
	0,					/* tp_descr_set */
	0,					/* tp_dictoffset */
	(initproc)green_init,			/* tp_init */
	GREENLET_tp_alloc,			/* tp_alloc */
	green_new,				/* tp_new */
	GREENLET_tp_free,			/* tp_free */        
	(inquiry)GREENLET_tp_is_gc,		/* tp_is_gc */
};
/* XXX need GC support */


static PyObject* mod_getcurrent(PyObject* self)
{
	if (!STATE_OK)
		return NULL;
	Py_INCREF(ts_current);
	return (PyObject*) ts_current;
}

static PyMethodDef GreenMethods[] = {
	{"getcurrent", (PyCFunction)mod_getcurrent, METH_NOARGS, /*XXX*/ NULL},
	{NULL,     NULL}        /* Sentinel */
};

static char* copy_on_greentype[] = {
	"getcurrent", "error", "GreenletExit", NULL
};

void initgreenlet(void)
{
	PyObject* m;
	char** p;
	_PyGreen_switchstack = g_switchstack;
	_PyGreen_slp_switch = slp_switch;
	_PyGreen_initialstub = g_initialstub;
	m = Py_InitModule("greenlet", GreenMethods);
	if (m == NULL)
		return;
	
	if (PyModule_AddStringConstant(m, "__version__", "0.2") < 0)
		return;

	ts_curkey = PyString_InternFromString("__greenlet_ts_curkey");
	ts_delkey = PyString_InternFromString("__greenlet_ts_delkey");
	if (ts_curkey == NULL || ts_delkey == NULL)
		return;
	if (PyType_Ready(&PyGreen_Type) < 0)
		return;
	PyExc_GreenletError = PyErr_NewException("greenlet.error", NULL, NULL);
	if (PyExc_GreenletError == NULL)
		return;
	PyExc_GreenletExit = PyErr_NewException("greenlet.GreenletExit",
						NULL, NULL);
	if (PyExc_GreenletExit == NULL)
		return;

	ts_current = green_create_main();
	if (ts_current == NULL)
		return;

	Py_INCREF(&PyGreen_Type);
	PyModule_AddObject(m, "greenlet", (PyObject*) &PyGreen_Type);
	Py_INCREF(PyExc_GreenletError);
	PyModule_AddObject(m, "error", PyExc_GreenletError);
	Py_INCREF(PyExc_GreenletExit);
	PyModule_AddObject(m, "GreenletExit", PyExc_GreenletExit);
#ifdef GREENLET_USE_GC
	PyModule_AddObject(m, "GREENLET_USE_GC", PyBool_FromLong(1));
#else
	PyModule_AddObject(m, "GREENLET_USE_GC", PyBool_FromLong(0));
#endif


        /* also publish module-level data as attributes of the greentype. */
	for (p=copy_on_greentype; *p; p++) {
		PyObject* o = PyObject_GetAttrString(m, *p);
		if (!o) continue;
		PyDict_SetItemString(PyGreen_Type.tp_dict, *p, o);
		Py_DECREF(o);
	}
}