mirror of https://github.com/python/cpython
381 lines
9.4 KiB
C
381 lines
9.4 KiB
C
/* Generator object implementation */
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#include "Python.h"
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#include "frameobject.h"
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#include "genobject.h"
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#include "ceval.h"
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#include "structmember.h"
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#include "opcode.h"
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static int
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gen_traverse(PyGenObject *gen, visitproc visit, void *arg)
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{
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Py_VISIT(gen->gi_frame);
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return 0;
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}
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static void
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gen_dealloc(PyGenObject *gen)
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{
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PyObject *self = (PyObject *) gen;
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_PyObject_GC_UNTRACK(gen);
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if (gen->gi_weakreflist != NULL)
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PyObject_ClearWeakRefs((PyObject *) gen);
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_PyObject_GC_TRACK(self);
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if (gen->gi_frame!=NULL && gen->gi_frame->f_stacktop!=NULL) {
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/* Generator is paused, so we need to close */
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gen->ob_type->tp_del(self);
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if (self->ob_refcnt > 0)
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return; /* resurrected. :( */
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}
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_PyObject_GC_UNTRACK(self);
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Py_XDECREF(gen->gi_frame);
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PyObject_GC_Del(gen);
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}
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static PyObject *
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gen_send_ex(PyGenObject *gen, PyObject *arg, int exc)
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{
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PyThreadState *tstate = PyThreadState_GET();
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PyFrameObject *f = gen->gi_frame;
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PyObject *result;
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if (gen->gi_running) {
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PyErr_SetString(PyExc_ValueError,
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"generator already executing");
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return NULL;
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}
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if (f==NULL || f->f_stacktop == NULL) {
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/* Only set exception if called from send() */
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if (arg && !exc) PyErr_SetNone(PyExc_StopIteration);
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return NULL;
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}
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if (f->f_lasti == -1) {
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if (arg && arg != Py_None) {
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PyErr_SetString(PyExc_TypeError,
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"can't send non-None value to a just-started generator");
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return NULL;
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}
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} else {
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/* Push arg onto the frame's value stack */
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result = arg ? arg : Py_None;
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Py_INCREF(result);
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*(f->f_stacktop++) = result;
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}
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/* Generators always return to their most recent caller, not
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* necessarily their creator. */
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Py_XINCREF(tstate->frame);
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assert(f->f_back == NULL);
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f->f_back = tstate->frame;
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gen->gi_running = 1;
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result = PyEval_EvalFrameEx(f, exc);
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gen->gi_running = 0;
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/* Don't keep the reference to f_back any longer than necessary. It
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* may keep a chain of frames alive or it could create a reference
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* cycle. */
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assert(f->f_back == tstate->frame);
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Py_CLEAR(f->f_back);
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/* If the generator just returned (as opposed to yielding), signal
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* that the generator is exhausted. */
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if (result == Py_None && f->f_stacktop == NULL) {
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Py_DECREF(result);
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result = NULL;
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/* Set exception if not called by gen_iternext() */
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if (arg) PyErr_SetNone(PyExc_StopIteration);
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}
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if (!result || f->f_stacktop == NULL) {
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/* generator can't be rerun, so release the frame */
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Py_DECREF(f);
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gen->gi_frame = NULL;
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}
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return result;
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}
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PyDoc_STRVAR(send_doc,
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"send(arg) -> send 'arg' into generator,\n\
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return next yielded value or raise StopIteration.");
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static PyObject *
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gen_send(PyGenObject *gen, PyObject *arg)
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{
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return gen_send_ex(gen, arg, 0);
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}
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PyDoc_STRVAR(close_doc,
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"close(arg) -> raise GeneratorExit inside generator.");
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static PyObject *
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gen_close(PyGenObject *gen, PyObject *args)
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{
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PyObject *retval;
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PyErr_SetNone(PyExc_GeneratorExit);
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retval = gen_send_ex(gen, Py_None, 1);
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if (retval) {
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Py_DECREF(retval);
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PyErr_SetString(PyExc_RuntimeError,
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"generator ignored GeneratorExit");
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return NULL;
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}
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if ( PyErr_ExceptionMatches(PyExc_StopIteration)
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|| PyErr_ExceptionMatches(PyExc_GeneratorExit) )
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{
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PyErr_Clear(); /* ignore these errors */
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Py_INCREF(Py_None);
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return Py_None;
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}
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return NULL;
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}
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static void
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gen_del(PyObject *self)
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{
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PyObject *res;
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PyObject *error_type, *error_value, *error_traceback;
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PyGenObject *gen = (PyGenObject *)self;
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if (!gen->gi_frame || gen->gi_frame->f_stacktop==NULL)
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/* Generator isn't paused, so no need to close */
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return;
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/* Temporarily resurrect the object. */
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assert(self->ob_refcnt == 0);
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self->ob_refcnt = 1;
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/* Save the current exception, if any. */
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PyErr_Fetch(&error_type, &error_value, &error_traceback);
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res = gen_close((PyGenObject *)self, NULL);
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if (res == NULL)
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PyErr_WriteUnraisable((PyObject *)self);
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else
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Py_DECREF(res);
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/* Restore the saved exception. */
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PyErr_Restore(error_type, error_value, error_traceback);
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/* Undo the temporary resurrection; can't use DECREF here, it would
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* cause a recursive call.
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*/
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assert(self->ob_refcnt > 0);
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if (--self->ob_refcnt == 0)
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return; /* this is the normal path out */
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/* close() resurrected it! Make it look like the original Py_DECREF
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* never happened.
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*/
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{
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Py_ssize_t refcnt = self->ob_refcnt;
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_Py_NewReference(self);
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self->ob_refcnt = refcnt;
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}
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assert(!PyType_IS_GC(self->ob_type) ||
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_Py_AS_GC(self)->gc.gc_refs != _PyGC_REFS_UNTRACKED);
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/* If Py_REF_DEBUG, _Py_NewReference bumped _Py_RefTotal, so
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* we need to undo that. */
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_Py_DEC_REFTOTAL;
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/* If Py_TRACE_REFS, _Py_NewReference re-added self to the object
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* chain, so no more to do there.
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* If COUNT_ALLOCS, the original decref bumped tp_frees, and
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* _Py_NewReference bumped tp_allocs: both of those need to be
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* undone.
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*/
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#ifdef COUNT_ALLOCS
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--self->ob_type->tp_frees;
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--self->ob_type->tp_allocs;
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#endif
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}
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PyDoc_STRVAR(throw_doc,
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"throw(typ[,val[,tb]]) -> raise exception in generator,\n\
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return next yielded value or raise StopIteration.");
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static PyObject *
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gen_throw(PyGenObject *gen, PyObject *args)
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{
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PyObject *typ;
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PyObject *tb = NULL;
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PyObject *val = NULL;
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if (!PyArg_ParseTuple(args, "O|OO:throw", &typ, &val, &tb))
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return NULL;
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/* First, check the traceback argument, replacing None with
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NULL. */
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if (tb == Py_None)
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tb = NULL;
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else if (tb != NULL && !PyTraceBack_Check(tb)) {
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PyErr_SetString(PyExc_TypeError,
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"throw() third argument must be a traceback object");
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return NULL;
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}
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Py_INCREF(typ);
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Py_XINCREF(val);
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Py_XINCREF(tb);
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if (PyExceptionClass_Check(typ)) {
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PyErr_NormalizeException(&typ, &val, &tb);
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}
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else if (PyExceptionInstance_Check(typ)) {
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/* Raising an instance. The value should be a dummy. */
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if (val && val != Py_None) {
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PyErr_SetString(PyExc_TypeError,
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"instance exception may not have a separate value");
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goto failed_throw;
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}
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else {
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/* Normalize to raise <class>, <instance> */
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Py_XDECREF(val);
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val = typ;
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typ = PyExceptionInstance_Class(typ);
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Py_INCREF(typ);
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}
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}
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/* Allow raising builtin string exceptions */
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else if (!PyString_CheckExact(typ)) {
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/* Not something you can raise. throw() fails. */
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PyErr_Format(PyExc_TypeError,
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"exceptions must be classes, or instances, not %s",
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typ->ob_type->tp_name);
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goto failed_throw;
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}
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PyErr_Restore(typ, val, tb);
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return gen_send_ex(gen, Py_None, 1);
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failed_throw:
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/* Didn't use our arguments, so restore their original refcounts */
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Py_DECREF(typ);
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Py_XDECREF(val);
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Py_XDECREF(tb);
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return NULL;
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}
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static PyObject *
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gen_iternext(PyGenObject *gen)
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{
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return gen_send_ex(gen, NULL, 0);
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}
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static PyMemberDef gen_memberlist[] = {
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{"gi_frame", T_OBJECT, offsetof(PyGenObject, gi_frame), RO},
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{"gi_running", T_INT, offsetof(PyGenObject, gi_running), RO},
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{NULL} /* Sentinel */
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};
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static PyMethodDef gen_methods[] = {
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{"send",(PyCFunction)gen_send, METH_O, send_doc},
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{"throw",(PyCFunction)gen_throw, METH_VARARGS, throw_doc},
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{"close",(PyCFunction)gen_close, METH_NOARGS, close_doc},
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{NULL, NULL} /* Sentinel */
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};
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PyTypeObject PyGen_Type = {
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PyObject_HEAD_INIT(&PyType_Type)
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0, /* ob_size */
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"generator", /* tp_name */
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sizeof(PyGenObject), /* tp_basicsize */
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0, /* tp_itemsize */
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/* methods */
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(destructor)gen_dealloc, /* tp_dealloc */
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0, /* tp_print */
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0, /* tp_getattr */
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0, /* tp_setattr */
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0, /* tp_compare */
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0, /* tp_repr */
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0, /* tp_as_number */
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0, /* tp_as_sequence */
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0, /* tp_as_mapping */
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0, /* tp_hash */
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0, /* tp_call */
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0, /* tp_str */
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PyObject_GenericGetAttr, /* tp_getattro */
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0, /* tp_setattro */
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0, /* tp_as_buffer */
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Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,/* tp_flags */
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0, /* tp_doc */
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(traverseproc)gen_traverse, /* tp_traverse */
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0, /* tp_clear */
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0, /* tp_richcompare */
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offsetof(PyGenObject, gi_weakreflist), /* tp_weaklistoffset */
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PyObject_SelfIter, /* tp_iter */
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(iternextfunc)gen_iternext, /* tp_iternext */
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gen_methods, /* tp_methods */
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gen_memberlist, /* tp_members */
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0, /* tp_getset */
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0, /* tp_base */
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0, /* tp_dict */
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0, /* tp_descr_get */
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0, /* tp_descr_set */
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0, /* tp_dictoffset */
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0, /* tp_init */
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0, /* tp_alloc */
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0, /* tp_new */
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0, /* tp_free */
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0, /* tp_is_gc */
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0, /* tp_bases */
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0, /* tp_mro */
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0, /* tp_cache */
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0, /* tp_subclasses */
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0, /* tp_weaklist */
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gen_del, /* tp_del */
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};
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PyObject *
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PyGen_New(PyFrameObject *f)
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{
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PyGenObject *gen = PyObject_GC_New(PyGenObject, &PyGen_Type);
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if (gen == NULL) {
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Py_DECREF(f);
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return NULL;
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}
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gen->gi_frame = f;
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gen->gi_running = 0;
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gen->gi_weakreflist = NULL;
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_PyObject_GC_TRACK(gen);
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return (PyObject *)gen;
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}
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int
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PyGen_NeedsFinalizing(PyGenObject *gen)
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{
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int i;
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PyFrameObject *f = gen->gi_frame;
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if (f == NULL || f->f_stacktop==NULL || f->f_iblock<=0)
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return 0; /* no frame or no blockstack == no finalization */
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for (i=f->f_iblock; i>=0; i--) {
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if (f->f_blockstack[i].b_type != SETUP_LOOP)
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/* any block type besides a loop requires cleanup */
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return 1;
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}
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/* No blocks except loops, it's safe to skip finalization */
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return 0;
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}
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