//     Copyright 2018, Kay Hayen, mailto:kay.hayen@gmail.com
//
//     Part of "Nuitka", an optimizing Python compiler that is compatible and
//     integrates with CPython, but also works on its own.
//
//     Licensed under the Apache License, Version 2.0 (the "License");
//     you may not use this file except in compliance with the License.
//     You may obtain a copy of the License at
//
//        http://www.apache.org/licenses/LICENSE-2.0
//
//     Unless required by applicable law or agreed to in writing, software
//     distributed under the License is distributed on an "AS IS" BASIS,
//     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//     See the License for the specific language governing permissions and
//     limitations under the License.
//
/** Compiled Generators.
 *
 * Unlike in CPython, we have one type for just generators, this doesn't do coroutines
 * nor asyncgen.
 *
 * It strives to be full replacement for normal generators, while providing also an
 * interface for quick iteration from compiled code.
 *
 */

#include "nuitka/prelude.h"

#include "nuitka/freelists.h"

// In a separate file, code to interact with uncompiled generators, that does
// all the quirks necessary to get those working.
#include "CompiledGeneratorTypeUncompiledIntegration.c"

static PyObject *Nuitka_Generator_tp_repr(struct Nuitka_GeneratorObject *generator) {
#if PYTHON_VERSION < 300
    return PyString_FromFormat("<compiled_generator object %s at %p>", Nuitka_String_AsString(generator->m_name),
                               generator);
#else
    return PyUnicode_FromFormat("<compiled_generator object %s at %p>",
#if PYTHON_VERSION < 350
                                Nuitka_String_AsString(generator->m_name),
#else
                                Nuitka_String_AsString(generator->m_qualname),
#endif
                                generator);
#endif
}

static long Nuitka_Generator_tp_traverse(struct Nuitka_GeneratorObject *generator, visitproc visit, void *arg) {
    // Not needed.
    // Py_VISIT( (PyObject *)generator->m_frame );

    return 0;
}

static void Nuitka_Generator_release_closure(struct Nuitka_GeneratorObject *generator) {
    for (Py_ssize_t i = 0; i < generator->m_closure_given; i++) {
        CHECK_OBJECT(generator->m_closure[i]);
        Py_DECREF(generator->m_closure[i]);
    }

    generator->m_closure_given = 0;
}

#if PYTHON_VERSION >= 300

PyObject *ERROR_GET_STOP_ITERATION_VALUE() {
    assert(PyErr_ExceptionMatches(PyExc_StopIteration));

    PyObject *exception_type, *exception_value;
    PyTracebackObject *exception_tb;
    FETCH_ERROR_OCCURRED(&exception_type, &exception_value, &exception_tb);

    Py_DECREF(exception_type);
    Py_XDECREF(exception_tb);

    PyObject *value = NULL;

    if (exception_value) {
        if (EXCEPTION_MATCH_BOOL_SINGLE(exception_value, PyExc_StopIteration)) {
            value = ((PyStopIterationObject *)exception_value)->value;
            Py_XINCREF(value);
            Py_DECREF(exception_value);
        } else {
            value = exception_value;
        }
    }

    if (value == NULL) {
        Py_INCREF(Py_None);
        value = Py_None;
    }

    return value;
}

extern PyObject *const_str_plain_send, *const_str_plain_throw, *const_str_plain_close;

#if PYTHON_VERSION >= 350
extern PyObject *_Nuitka_Coroutine_throw2(struct Nuitka_CoroutineObject *coroutine, bool closing,
                                          PyObject *exception_type, PyObject *exception_value,
                                          PyTracebackObject *exception_tb);
#endif

#if PYTHON_VERSION < 350
static
#endif
    PyObject *
    _Nuitka_YieldFromPassExceptionTo(PyObject *value, PyObject *exception_type, PyObject *exception_value,
                                     PyTracebackObject *exception_tb) {
    // The yielding generator is being closed, but we also are tasked to
    // immediately close the currently running sub-generator.
    if (EXCEPTION_MATCH_BOOL_SINGLE(exception_type, PyExc_GeneratorExit)) {
        PyObject *close_method = PyObject_GetAttr(value, const_str_plain_close);

        if (close_method) {
            PyObject *close_value = PyObject_Call(close_method, const_tuple_empty, NULL);
            Py_DECREF(close_method);

            if (unlikely(close_value == NULL)) {
                Py_DECREF(exception_type);
                Py_XDECREF(exception_value);
                Py_XDECREF(exception_tb);

                return NULL;
            }

            Py_DECREF(close_value);
        } else {
            PyObject *error = GET_ERROR_OCCURRED();

            if (error != NULL && !EXCEPTION_MATCH_BOOL_SINGLE(error, PyExc_AttributeError)) {
                PyErr_WriteUnraisable((PyObject *)value);
            }
        }

        RESTORE_ERROR_OCCURRED(exception_type, exception_value, exception_tb);

        return NULL;
    }

#if NUITKA_UNCOMPILED_THROW_INTEGRATION
    if (PyGen_CheckExact(value)
#if PYTHON_VERSION >= 350
        || PyCoro_CheckExact(value)
#endif
    ) {
        PyGenObject *gen = (PyGenObject *)value;

        PyObject *result = Nuitka_UncompiledGenerator_throw(gen,
                                                            0, // ??
                                                            exception_type, exception_value, (PyObject *)exception_tb);

        Py_DECREF(exception_type);
        Py_XDECREF(exception_value);
        Py_XDECREF(exception_tb);

        return result;
    } else
#endif
#if PYTHON_VERSION >= 350
        if (Nuitka_Coroutine_Check(value)) {
        struct Nuitka_CoroutineObject *coro = ((struct Nuitka_CoroutineObject *)value);

        return _Nuitka_Coroutine_throw2(coro, false, exception_type, exception_value, exception_tb);
    } else if (Nuitka_CoroutineWrapper_Check(value)) {
        struct Nuitka_CoroutineObject *coro = ((struct Nuitka_CoroutineWrapperObject *)value)->m_coroutine;

        return _Nuitka_Coroutine_throw2(coro, false, exception_type, exception_value, exception_tb);
    } else
#endif
    {
        PyObject *throw_method = PyObject_GetAttr(value, const_str_plain_throw);

        if (throw_method) {
            PyObject *result =
                PyObject_CallFunctionObjArgs(throw_method, exception_type, exception_value, exception_tb, NULL);
            Py_DECREF(throw_method);

            Py_DECREF(exception_type);
            Py_XDECREF(exception_value);
            Py_XDECREF(exception_tb);

            return result;
        } else if (EXCEPTION_MATCH_BOOL_SINGLE(GET_ERROR_OCCURRED(), PyExc_AttributeError)) {
            RESTORE_ERROR_OCCURRED(exception_type, exception_value, exception_tb);

            return NULL;
        } else {
            assert(ERROR_OCCURRED());

            Py_DECREF(exception_type);
            Py_XDECREF(exception_value);
            Py_XDECREF(exception_tb);

            return NULL;
        }
    }
}

static PyObject *_Nuitka_YieldFromGeneratorCore(struct Nuitka_GeneratorObject *generator, PyObject *yieldfrom,
                                                PyObject *send_value) {
    // Send iteration value to the sub-generator, which may be a CPython
    // generator object, something with an iterator next, or a send method,
    // where the later is only required if values other than "None" need to
    // be passed in.
    CHECK_OBJECT(yieldfrom);
    assert(send_value != NULL || ERROR_OCCURRED());

    PyObject *retval;

#if 0
    PRINT_STRING("YIELD CORE:");
    PRINT_ITEM( value );
    PRINT_ITEM( send_value );

    PRINT_NEW_LINE();
#endif

    assert(send_value != NULL || ERROR_OCCURRED());

    PyObject *exception_type, *exception_value;
    PyTracebackObject *exception_tb;
    FETCH_ERROR_OCCURRED(&exception_type, &exception_value, &exception_tb);

    // Exception, was thrown into us, need to send that to sub-generator.
    if (exception_type != NULL) {
        retval = _Nuitka_YieldFromPassExceptionTo(yieldfrom, exception_type, exception_value, exception_tb);

        if (unlikely(send_value == NULL)) {
            PyObject *error = GET_ERROR_OCCURRED();

            if (error != NULL && EXCEPTION_MATCH_BOOL_SINGLE(error, PyExc_StopIteration)) {
                generator->m_returned = ERROR_GET_STOP_ITERATION_VALUE();

                assert(!ERROR_OCCURRED());
                return NULL;
            }
        }
    } else if (PyGen_CheckExact(yieldfrom)) {
        retval = PyGen_Send((PyGenObject *)yieldfrom, Py_None);
    }
#if PYTHON_VERSION >= 350
    else if (PyCoro_CheckExact(yieldfrom)) {
        retval = PyGen_Send((PyGenObject *)yieldfrom, Py_None);
    }
#endif
    else if (send_value == Py_None && Py_TYPE(yieldfrom)->tp_iternext != NULL) {
        retval = Py_TYPE(yieldfrom)->tp_iternext(yieldfrom);
    } else {
        // Bug compatibility here, before 3.3 tuples were unrolled in calls, which is what
        // PyObject_CallMethod does.
#if PYTHON_VERSION >= 340
        retval = PyObject_CallMethodObjArgs(yieldfrom, const_str_plain_send, send_value, NULL);
#else
        retval = PyObject_CallMethod(yieldfrom, (char *)"send", (char *)"O", send_value);
#endif
    }

    // Check the sub-generator result
    if (retval == NULL) {
        PyObject *error = GET_ERROR_OCCURRED();

        if (error == NULL) {
            Py_INCREF(Py_None);
            generator->m_returned = Py_None;
        } else if (likely(EXCEPTION_MATCH_BOOL_SINGLE(error, PyExc_StopIteration))) {
            // The sub-generator has given an exception. In case of
            // StopIteration, we need to check the value, as it is going to be
            // the expression value of this "yield from", and we are done. All
            // other errors, we need to raise.
            generator->m_returned = ERROR_GET_STOP_ITERATION_VALUE();
            assert(!ERROR_OCCURRED());
        }

        return NULL;
    } else {
        return retval;
    }
}

static PyObject *Nuitka_YieldFromGeneratorCore(struct Nuitka_GeneratorObject *generator, PyObject *send_value) {
    PyObject *yieldfrom = generator->m_yieldfrom;
    assert(yieldfrom);

    // Need to make it unaccessible while using it.
    generator->m_yieldfrom = NULL;
    PyObject *yielded = _Nuitka_YieldFromGeneratorCore(generator, yieldfrom, send_value);

    if (yielded == NULL) {
        Py_DECREF(yieldfrom);

        if (generator->m_returned != NULL) {
            PyObject *yield_from_result = generator->m_returned;
            generator->m_returned = NULL;

            yielded = ((generator_code)generator->m_code)(generator, yield_from_result);
        } else {
            assert(ERROR_OCCURRED());
            yielded = ((generator_code)generator->m_code)(generator, NULL);
        }

#if 0
        if ( ERROR_OCCURRED() )
        {
            yielded = ((generator_code)generator->m_code)( generator, NULL );
        }
        else
        {
            PyObject *yield_from_result = generator->m_returned;
            generator->m_returned = NULL;

            yielded = ((generator_code)generator->m_code)( generator, yield_from_result );
        }
#endif
    } else {
        generator->m_yieldfrom = yieldfrom;
    }

    return yielded;
}

static PyObject *Nuitka_YieldFromGeneratorInitial(struct Nuitka_GeneratorObject *generator) {
    // Coroutines are already perfect for yielding from.
#if PYTHON_VERSION >= 350
    if (PyCoro_CheckExact(generator->m_yieldfrom) || Nuitka_Coroutine_Check(generator->m_yieldfrom)) {
        if (unlikely((generator->m_code_object->co_flags & CO_ITERABLE_COROUTINE) == 0)) {
            Py_DECREF(generator->m_yieldfrom);
            generator->m_yieldfrom = NULL;

            PyErr_Format(PyExc_TypeError, "cannot 'yield from' a coroutine object in a non-coroutine generator");
            return NULL;
        }
    } else
#endif
    {
        PyObject *old = generator->m_yieldfrom;
        generator->m_yieldfrom = MAKE_ITERATOR(generator->m_yieldfrom);
        Py_DECREF(old);

        if (unlikely(generator->m_yieldfrom == NULL)) {
            return NULL;
        }
    }

    return Nuitka_YieldFromGeneratorCore(generator, Py_None);
}

static PyObject *Nuitka_YieldFromGeneratorNext(struct Nuitka_GeneratorObject *generator, PyObject *send_value) {
    PyObject *result = Nuitka_YieldFromGeneratorCore(generator, send_value);

#if 0
    PRINT_STRING("RES:");
    PRINT_ITEM( result );
    PRINT_NEW_LINE();
#endif

    return result;
}

#endif

static PyObject *Nuitka_Generator_send2(struct Nuitka_GeneratorObject *generator, PyObject *value,
                                        PyObject *exception_type, PyObject *exception_value,
                                        PyTracebackObject *exception_tb) {
    CHECK_OBJECT(generator);

    if (generator->m_status != status_Finished) {
        PyThreadState *thread_state = PyThreadState_GET();

#if PYTHON_VERSION < 300
        PyObject *saved_exception_type = thread_state->exc_type;
        PyObject *saved_exception_value = NULL;
        PyTracebackObject *saved_exception_traceback = NULL;

        if (saved_exception_type != Py_None && saved_exception_type != NULL) {
            saved_exception_value = thread_state->exc_value;
            Py_INCREF(saved_exception_type);
            Py_XINCREF(saved_exception_value);
            saved_exception_traceback = (PyTracebackObject *)thread_state->exc_traceback;
            Py_XINCREF(saved_exception_traceback);
        }
#endif

        if (generator->m_running) {
            PyErr_Format(PyExc_ValueError, "generator already executing");
            return NULL;
        }

        if (generator->m_status == status_Unused) {
            generator->m_status = status_Running;
        }

        // Put the generator back on the frame stack.
        PyFrameObject *return_frame = thread_state->frame;
#ifndef __NUITKA_NO_ASSERT__
        if (return_frame) {
            assertFrameObject((struct Nuitka_FrameObject *)return_frame);
        }
#endif

        if (generator->m_frame) {
            // It would be nice if our frame were still alive. Nobody had the
            // right to release it.
            assertFrameObject(generator->m_frame);

            // It's not supposed to be on the top right now.
            assert(return_frame != &generator->m_frame->m_frame);

            Py_XINCREF(return_frame);
            generator->m_frame->m_frame.f_back = return_frame;

            thread_state->frame = &generator->m_frame->m_frame;
        }

        // Continue the yielder function while preventing recursion.
        generator->m_running = true;

        // Check for thrown exception. TODO: Pass these the the entry point
        // maybe.
        if (unlikely(exception_type)) {
            assert(value == NULL);

            RESTORE_ERROR_OCCURRED(exception_type, exception_value, exception_tb);
        }

        if (generator->m_frame) {
            Nuitka_Frame_MarkAsExecuting(generator->m_frame);
        }

#if PYTHON_VERSION >= 300
        PyObject *yielded;

        if (generator->m_yieldfrom == NULL) {
            yielded = ((generator_code)generator->m_code)(generator, value);
        } else {
            yielded = Nuitka_YieldFromGeneratorNext(generator, value);
        }
#else
        PyObject *yielded = ((generator_code)generator->m_code)(generator, value);
#endif

#if PYTHON_VERSION >= 300
        // If the generator returns with m_yieldfrom set, it wants us to yield
        // from that value from now on.
        while (yielded == NULL && generator->m_yieldfrom != NULL) {
            yielded = Nuitka_YieldFromGeneratorInitial(generator);
        }
#endif
        if (generator->m_frame) {
            Nuitka_Frame_MarkAsNotExecuting(generator->m_frame);
        }

        generator->m_running = false;

        thread_state = PyThreadState_GET();

        // Remove the generator from the frame stack.
        if (generator->m_frame) {
            assert(thread_state->frame == &generator->m_frame->m_frame);
            assertFrameObject(generator->m_frame);

            Py_CLEAR(generator->m_frame->m_frame.f_back);
        }

        thread_state->frame = return_frame;

        if (yielded == NULL) {
            generator->m_status = status_Finished;

            if (generator->m_frame != NULL) {
#if PYTHON_VERSION >= 340
                generator->m_frame->m_frame.f_gen = NULL;
#endif
                Py_DECREF(generator->m_frame);
                generator->m_frame = NULL;
            }

            Nuitka_Generator_release_closure(generator);

#if PYTHON_VERSION < 300
            if (saved_exception_type != NULL && saved_exception_type != Py_None) {
                Py_DECREF(saved_exception_type);
                Py_XDECREF(saved_exception_value);
                Py_XDECREF(saved_exception_traceback);
            }
#endif

#if PYTHON_VERSION >= 350
            if (
#if PYTHON_VERSION < 370
                generator->m_code_object->co_flags & CO_FUTURE_GENERATOR_STOP &&
#endif
                GET_ERROR_OCCURRED() == PyExc_StopIteration) {
                PyObject *saved_exception_type, *saved_exception_value;
                PyTracebackObject *saved_exception_tb;

                FETCH_ERROR_OCCURRED(&saved_exception_type, &saved_exception_value, &saved_exception_tb);
                NORMALIZE_EXCEPTION(&saved_exception_type, &saved_exception_value, &saved_exception_tb);

                PyErr_Format(PyExc_RuntimeError, "generator raised StopIteration");

                FETCH_ERROR_OCCURRED(&exception_type, &exception_value, &exception_tb);

                RAISE_EXCEPTION_WITH_CAUSE(&exception_type, &exception_value, &exception_tb, saved_exception_value);

                CHECK_OBJECT(exception_value);
                CHECK_OBJECT(saved_exception_value);

                Py_INCREF(saved_exception_value);
                PyException_SetContext(exception_value, saved_exception_value);

                Py_DECREF(saved_exception_type);
                Py_XDECREF(saved_exception_tb);

                RESTORE_ERROR_OCCURRED(exception_type, exception_value, exception_tb);

                return NULL;
            }
#endif

            // Create StopIteration if necessary, i.e. return value that is not "None" was
            // given. TODO: Push this further down the user line, we might be able to avoid
            // it for some uses, e.g. quick iteration entirely.
#if PYTHON_VERSION >= 300
            if (generator->m_returned) {
                if (generator->m_returned != Py_None) {
                    Nuitka_SetStopIterationValue(generator->m_returned);
                }

                Py_DECREF(generator->m_returned);
                generator->m_returned = NULL;
            }
#endif

            return NULL;
        } else {
#if PYTHON_VERSION < 300
            PyObject *old_type = thread_state->exc_type;
            PyObject *old_value = thread_state->exc_value;
            PyTracebackObject *old_tb = (PyTracebackObject *)thread_state->exc_traceback;

            // Set sys attributes in the fastest possible way.
            PyObject *sys_dict = thread_state->interp->sysdict;
            CHECK_OBJECT(sys_dict);

            if (saved_exception_type != NULL && saved_exception_type != Py_None) {
                thread_state->exc_type = saved_exception_type;
                thread_state->exc_value = saved_exception_value;
                thread_state->exc_traceback = (PyObject *)saved_exception_traceback;

                Py_XDECREF(old_type);
                Py_XDECREF(old_value);
                Py_XDECREF(old_tb);

                if (old_type != saved_exception_type) {
                    PyDict_SetItem(sys_dict, const_str_plain_exc_type, saved_exception_type);
                }
                if (saved_exception_value != old_value) {
                    PyDict_SetItem(sys_dict, const_str_plain_exc_value,
                                   saved_exception_value ? saved_exception_value : Py_None);
                }
                if (saved_exception_traceback != old_tb) {
                    PyDict_SetItem(sys_dict, const_str_plain_exc_traceback,
                                   saved_exception_traceback ? (PyObject *)saved_exception_traceback : Py_None);
                }
            } else {
                thread_state->exc_type = Py_None;
                thread_state->exc_value = Py_None;
                thread_state->exc_traceback = (PyObject *)Py_None;

                Py_INCREF(Py_None);
                Py_INCREF(Py_None);
                Py_INCREF(Py_None);

                Py_XDECREF(old_type);
                Py_XDECREF(old_value);
                Py_XDECREF(old_tb);

                if (old_type != Py_None) {
                    PyDict_SetItem(sys_dict, const_str_plain_exc_type, Py_None);
                }
                if (old_value != Py_None) {
                    PyDict_SetItem(sys_dict, const_str_plain_exc_value, Py_None);
                }
                if (old_tb != (PyTracebackObject *)Py_None) {
                    PyDict_SetItem(sys_dict, const_str_plain_exc_traceback, Py_None);
                }
            }
#endif

            return yielded;
        }
    } else {
        return NULL;
    }
}

static PyObject *Nuitka_Generator_send(struct Nuitka_GeneratorObject *generator, PyObject *value) {
    if (generator->m_status == status_Unused && value != NULL && value != Py_None) {
        PyErr_Format(PyExc_TypeError, "can't send non-None value to a just-started generator");
        return NULL;
    }

    PyObject *result = Nuitka_Generator_send2(generator, value, NULL, NULL, NULL);

    if (result == NULL) {
        if (GET_ERROR_OCCURRED() == NULL) {
            RESTORE_ERROR_OCCURRED(PyExc_StopIteration, NULL, NULL);
            Py_INCREF(PyExc_StopIteration);
        }
    }

    return result;
}

static PyObject *Nuitka_Generator_tp_iternext(struct Nuitka_GeneratorObject *generator) {
    return Nuitka_Generator_send2(generator, Py_None, NULL, NULL, NULL);
}

/* Our own qiter interface, which is for quicker simple loop style iteration,
   that does not send anything in. */
PyObject *Nuitka_Generator_qiter(struct Nuitka_GeneratorObject *generator, bool *finished) {
    PyObject *result = Nuitka_Generator_send2(generator, Py_None, NULL, NULL, NULL);

    if (result == NULL) {
        if (unlikely(!CHECK_AND_CLEAR_STOP_ITERATION_OCCURRED())) {
            *finished = false;
            return NULL;
        }

        *finished = true;
        return NULL;
    }

    *finished = false;
    return result;
}

#if PYTHON_VERSION < 340
static
#endif
    PyObject *
    Nuitka_Generator_close(struct Nuitka_GeneratorObject *generator, PyObject *args) {
    if (generator->m_status == status_Running) {
        Py_INCREF(PyExc_GeneratorExit);

        PyObject *result = Nuitka_Generator_send2(generator, NULL, PyExc_GeneratorExit, NULL, NULL);

        if (unlikely(result)) {
            Py_DECREF(result);

            PyErr_Format(PyExc_RuntimeError, "generator ignored GeneratorExit");
            return NULL;
        } else {
            PyObject *error = GET_ERROR_OCCURRED();

            // StopIteration as exception.
            if (error == NULL) {
                Py_INCREF(Py_None);
                return Py_None;
            }

            // Maybe another acceptable exception for generator exit.
            if (EXCEPTION_MATCH_GENERATOR(error)) {
                CLEAR_ERROR_OCCURRED();

                Py_INCREF(Py_None);
                return Py_None;
            }

            return NULL;
        }
    }

    Py_INCREF(Py_None);
    return Py_None;
}

static PyObject *Nuitka_Generator_throw(struct Nuitka_GeneratorObject *generator, PyObject *args) {
    PyObject *exception_type;
    PyObject *exception_value = NULL;
    PyTracebackObject *exception_tb = NULL;

    // This takes no references, that is for us to do.
    int res = PyArg_UnpackTuple(args, "throw", 1, 3, &exception_type, &exception_value, &exception_tb);

    if (unlikely(res == 0)) {
        return NULL;
    }

    // Check traceback limitations.
    if ((PyObject *)exception_tb == Py_None) {
        exception_tb = NULL;
    } else if (exception_tb != NULL && !PyTraceBack_Check(exception_tb)) {
        PyErr_Format(PyExc_TypeError, "throw() third argument must be a traceback object");

        return NULL;
    }

    if (PyExceptionClass_Check(exception_type)) {
        Py_INCREF(exception_type);
        Py_XINCREF(exception_value);
        Py_XINCREF(exception_tb);

#if PYTHON_VERSION >= 300
        // During a "yield from", the normalize is not done.
        if (generator->m_yieldfrom == NULL) {
#endif
            NORMALIZE_EXCEPTION(&exception_type, &exception_value, &exception_tb);
#if PYTHON_VERSION >= 300
        }
#endif
    } else if (PyExceptionInstance_Check(exception_type)) {
        if (exception_value != NULL && exception_value != Py_None) {
            PyErr_Format(PyExc_TypeError, "instance exception may not have a separate value");
            return NULL;
        }

        exception_value = exception_type;
        Py_INCREF(exception_value);
        exception_type = PyExceptionInstance_Class(exception_type);
        Py_INCREF(exception_type);
        Py_XINCREF(exception_tb);
    } else {
        PyErr_Format(PyExc_TypeError,
#if PYTHON_VERSION < 300
                     "exceptions must be classes, or instances, not %s",
#else
                     "exceptions must be classes or instances deriving from BaseException, not %s",
#endif
                     Py_TYPE(exception_type)->tp_name);

        return NULL;
    }

    if (generator->m_status == status_Running) {
        PyObject *result = Nuitka_Generator_send2(generator, NULL, exception_type, exception_value, exception_tb);

        if (result == NULL) {
            if (GET_ERROR_OCCURRED() == NULL) {
                RESTORE_ERROR_OCCURRED(PyExc_StopIteration, NULL, NULL);
                Py_INCREF(PyExc_StopIteration);
            }
        }

        return result;
    } else if (generator->m_status == status_Finished) {
        RESTORE_ERROR_OCCURRED(exception_type, exception_value, exception_tb);

        return NULL;
    } else {
        if (exception_tb == NULL) {
            // TODO: Our compiled objects really need a way to store common
            // stuff in a "shared" part across all instances, and outside of
            // run time, so we could reuse this.
            struct Nuitka_FrameObject *frame = MAKE_FUNCTION_FRAME(generator->m_code_object, generator->m_module, 0);

            exception_tb = MAKE_TRACEBACK(frame, generator->m_code_object->co_firstlineno);

            Py_DECREF(frame);
        }

        RESTORE_ERROR_OCCURRED(exception_type, exception_value, exception_tb);

        generator->m_status = status_Finished;

        return NULL;
    }
}

#if PYTHON_VERSION >= 340
static void Nuitka_Generator_tp_finalizer(struct Nuitka_GeneratorObject *generator) {
    if (generator->m_status != status_Running) {
        return;
    }

    PyObject *error_type, *error_value;
    PyTracebackObject *error_traceback;

    FETCH_ERROR_OCCURRED(&error_type, &error_value, &error_traceback);

    PyObject *close_result = Nuitka_Generator_close(generator, NULL);

    if (unlikely(close_result == NULL)) {
        PyErr_WriteUnraisable((PyObject *)generator);
    } else {
        Py_DECREF(close_result);
    }

#if PYTHON_VERSION >= 370
    Py_XDECREF(generator->m_exc_state.exc_type);
    Py_XDECREF(generator->m_exc_state.exc_value);
    Py_XDECREF(generator->m_exc_state.exc_traceback);
#endif

    /* Restore the saved exception if any. */
    RESTORE_ERROR_OCCURRED(error_type, error_value, error_traceback);
}

#endif

#define MAX_GENERATOR_FREE_LIST_COUNT 100
static struct Nuitka_GeneratorObject *free_list_generators = NULL;
static int free_list_generators_count = 0;

static void Nuitka_Generator_tp_dealloc(struct Nuitka_GeneratorObject *generator) {
    // Revive temporarily.
    assert(Py_REFCNT(generator) == 0);
    Py_REFCNT(generator) = 1;

    // Save the current exception, if any, we must preserve it.
    PyObject *save_exception_type, *save_exception_value;
    PyTracebackObject *save_exception_tb;
    FETCH_ERROR_OCCURRED(&save_exception_type, &save_exception_value, &save_exception_tb);

    if (generator->m_status == status_Running) {
        PyObject *close_result = Nuitka_Generator_close(generator, NULL);

        if (unlikely(close_result == NULL)) {
            PyErr_WriteUnraisable((PyObject *)generator);
        } else {
            Py_DECREF(close_result);
        }
    }

    Nuitka_Generator_release_closure(generator);

    if (generator->m_frame != NULL) {
#if PYTHON_VERSION >= 340
        generator->m_frame->m_frame.f_gen = NULL;
#endif
        Py_DECREF(generator->m_frame);
        generator->m_frame = NULL;
    }

    assert(Py_REFCNT(generator) == 1);
    Py_REFCNT(generator) = 0;

    // Now it is safe to release references and memory for it.
    Nuitka_GC_UnTrack(generator);

    if (generator->m_weakrefs != NULL) {
        PyObject_ClearWeakRefs((PyObject *)generator);
        assert(!ERROR_OCCURRED());
    }

    Py_DECREF(generator->m_name);

#if PYTHON_VERSION >= 350
    Py_DECREF(generator->m_qualname);
#endif

    /* Put the object into freelist or release to GC */
    releaseToFreeList(free_list_generators, generator, MAX_GENERATOR_FREE_LIST_COUNT);

    RESTORE_ERROR_OCCURRED(save_exception_type, save_exception_value, save_exception_tb);
}

static PyObject *Nuitka_Generator_get_name(struct Nuitka_GeneratorObject *generator) {
    PyObject *result = generator->m_name;
    Py_INCREF(result);
    return result;
}

#if PYTHON_VERSION >= 350
static int Nuitka_Generator_set_name(struct Nuitka_GeneratorObject *generator, PyObject *value) {
    // Cannot be deleted, not be non-unicode value.
    if (unlikely((value == NULL) || !PyUnicode_Check(value))) {
        PyErr_Format(PyExc_TypeError, "__name__ must be set to a string object");

        return -1;
    }

    PyObject *tmp = generator->m_name;
    Py_INCREF(value);
    generator->m_name = value;
    Py_DECREF(tmp);

    return 0;
}

static PyObject *Nuitka_Generator_get_qualname(struct Nuitka_GeneratorObject *generator) {
    PyObject *result = generator->m_qualname;
    Py_INCREF(result);
    return result;
}

static int Nuitka_Generator_set_qualname(struct Nuitka_GeneratorObject *generator, PyObject *value) {
    // Cannot be deleted, not be non-unicode value.
    if (unlikely((value == NULL) || !PyUnicode_Check(value))) {
        PyErr_Format(PyExc_TypeError, "__qualname__ must be set to a string object");

        return -1;
    }

    PyObject *tmp = generator->m_qualname;
    Py_INCREF(value);
    generator->m_qualname = value;
    Py_DECREF(tmp);

    return 0;
}

static PyObject *Nuitka_Generator_get_yieldfrom(struct Nuitka_GeneratorObject *generator) {
    if (generator->m_yieldfrom) {
        Py_INCREF(generator->m_yieldfrom);
        return generator->m_yieldfrom;
    } else {
        Py_INCREF(Py_None);
        return Py_None;
    }
}

#endif

static PyObject *Nuitka_Generator_get_code(struct Nuitka_GeneratorObject *generator) {
    PyObject *result = (PyObject *)generator->m_code_object;
    Py_INCREF(result);
    return result;
}

static int Nuitka_Generator_set_code(struct Nuitka_GeneratorObject *generator, PyObject *value) {
    PyErr_Format(PyExc_RuntimeError, "gi_code is not writable in Nuitka");
    return -1;
}

static PyObject *Nuitka_Generator_get_frame(struct Nuitka_GeneratorObject *generator) {
    PyObject *result;

    if (generator->m_frame) {
        result = (PyObject *)generator->m_frame;
    } else {
        result = Py_None;
    }

    Py_INCREF(result);
    return result;
}

static int Nuitka_Generator_set_frame(struct Nuitka_GeneratorObject *generator, PyObject *value) {
    PyErr_Format(PyExc_RuntimeError, "gi_frame is not writable in Nuitka");
    return -1;
}

static PyGetSetDef Nuitka_Generator_getsetlist[] = {
#if PYTHON_VERSION < 350
    {(char *)"__name__", (getter)Nuitka_Generator_get_name, NULL, NULL},
#else
    {(char *)"__name__", (getter)Nuitka_Generator_get_name, (setter)Nuitka_Generator_set_name, NULL},
    {(char *)"__qualname__", (getter)Nuitka_Generator_get_qualname, (setter)Nuitka_Generator_set_qualname, NULL},
    {(char *)"gi_yieldfrom", (getter)Nuitka_Generator_get_yieldfrom, NULL, NULL},
#endif
    {(char *)"gi_code", (getter)Nuitka_Generator_get_code, (setter)Nuitka_Generator_set_code, NULL},
    {(char *)"gi_frame", (getter)Nuitka_Generator_get_frame, (setter)Nuitka_Generator_set_frame, NULL},

    {NULL}};

static PyMethodDef Nuitka_Generator_methods[] = {{"send", (PyCFunction)Nuitka_Generator_send, METH_O, NULL},
                                                 {"throw", (PyCFunction)Nuitka_Generator_throw, METH_VARARGS, NULL},
                                                 {"close", (PyCFunction)Nuitka_Generator_close, METH_NOARGS, NULL},
                                                 {NULL}};

#include <structmember.h>

static PyMemberDef Nuitka_Generator_members[] = {
/* The type of "gi_running" changed in Python3. */
#if PYTHON_VERSION < 300
    {(char *)"gi_running", T_INT, offsetof(struct Nuitka_GeneratorObject, m_running), READONLY},
#else
    {(char *)"gi_running", T_BOOL, offsetof(struct Nuitka_GeneratorObject, m_running), READONLY},
#endif
    {NULL}};

PyTypeObject Nuitka_Generator_Type = {
    PyVarObject_HEAD_INIT(NULL, 0) "compiled_generator", /* tp_name */
    sizeof(struct Nuitka_GeneratorObject),               /* tp_basicsize */
    sizeof(struct Nuitka_CellObject *),                  /* tp_itemsize */
    (destructor)Nuitka_Generator_tp_dealloc,             /* tp_dealloc */
    0,                                                   /* tp_print */
    0,                                                   /* tp_getattr */
    0,                                                   /* tp_setattr */
    0,                                                   /* tp_compare */
    (reprfunc)Nuitka_Generator_tp_repr,                  /* tp_repr */
    0,                                                   /* tp_as_number */
    0,                                                   /* tp_as_sequence */
    0,                                                   /* tp_as_mapping */
    0,                                                   /* tp_hash */
    0,                                                   /* tp_call */
    0,                                                   /* tp_str */
    PyObject_GenericGetAttr,                             /* tp_getattro */
    0,                                                   /* tp_setattro */
    0,                                                   /* tp_as_buffer */
#if PYTHON_VERSION < 340
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
#else
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,
#endif
    /* tp_flags */
    0,                                                   /* tp_doc */
    (traverseproc)Nuitka_Generator_tp_traverse,          /* tp_traverse */
    0,                                                   /* tp_clear */
    0,                                                   /* tp_richcompare */
    offsetof(struct Nuitka_GeneratorObject, m_weakrefs), /* tp_weaklistoffset */
    PyObject_SelfIter,                                   /* tp_iter */
    (iternextfunc)Nuitka_Generator_tp_iternext,          /* tp_iternext */
    Nuitka_Generator_methods,                            /* tp_methods */
    Nuitka_Generator_members,                            /* tp_members */
    Nuitka_Generator_getsetlist,                         /* tp_getset */
    0,                                                   /* tp_base */
    0,                                                   /* tp_dict */
    0,                                                   /* tp_descr_get */
    0,                                                   /* tp_descr_set */
    0,                                                   /* tp_dictoffset */
    0,                                                   /* tp_init */
    0,                                                   /* tp_alloc */
    0,                                                   /* tp_new */
    0,                                                   /* tp_free */
    0,                                                   /* tp_is_gc */
    0,                                                   /* tp_bases */
    0,                                                   /* tp_mro */
    0,                                                   /* tp_cache */
    0,                                                   /* tp_subclasses */
    0,                                                   /* tp_weaklist */
    0,                                                   /* tp_del */
    0                                                    /* tp_version_tag */
#if PYTHON_VERSION >= 340
    ,
    (destructor)Nuitka_Generator_tp_finalizer /* tp_finalizer */
#endif
};

void _initCompiledGeneratorType(void) { PyType_Ready(&Nuitka_Generator_Type); }

PyObject *Nuitka_Generator_New(generator_code code, PyObject *module, PyObject *name,
#if PYTHON_VERSION >= 350
                               PyObject *qualname,
#endif
                               PyCodeObject *code_object, Py_ssize_t closure_given, Py_ssize_t heap_storage_size) {
    struct Nuitka_GeneratorObject *result;

    // TODO: Change the var part of the type to 1 maybe
    Py_ssize_t full_size = closure_given + (heap_storage_size + sizeof(void *) - 1) / sizeof(void *);

    // Macro to assign result memory from GC or free list.
    allocateFromFreeList(free_list_generators, struct Nuitka_GeneratorObject, Nuitka_Generator_Type, full_size);

    // For quicker access of generator heap.
    result->m_heap_storage = &result->m_closure[closure_given];

    assert(result != NULL);
    CHECK_OBJECT(result);

    assert(Py_SIZE(result) >= closure_given);

    result->m_code = (void *)code;

    CHECK_OBJECT(module);
    result->m_module = module;

    CHECK_OBJECT(name);
    result->m_name = name;
    Py_INCREF(name);

#if PYTHON_VERSION >= 350
    // The "qualname" defaults to NULL for most compact C code.
    if (qualname == NULL) {
        qualname = name;
    }
    CHECK_OBJECT(qualname);

    result->m_qualname = qualname;
    Py_INCREF(qualname);
#endif

#if PYTHON_VERSION >= 300
    result->m_yieldfrom = NULL;
#endif

    /* Note: The closure is set externally. */
    result->m_closure_given = closure_given;

    result->m_weakrefs = NULL;

    result->m_status = status_Unused;
    result->m_running = false;

    result->m_exception_type = NULL;
    result->m_exception_value = NULL;
    result->m_exception_tb = NULL;

    result->m_yield_return_index = 0;

#if PYTHON_VERSION >= 300
    result->m_returned = NULL;
#endif

    result->m_frame = NULL;
    result->m_code_object = code_object;

    Nuitka_GC_Track(result);
    return (PyObject *)result;
}
