text: /*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:4;tab-width:8;coding:utf-8 -*-│
  │vi: set net ft=c ts=4 sts=4 sw=4 fenc=utf-8                                :vi│
  ╞══════════════════════════════════════════════════════════════════════════════╡
  │ Python 3                                                                     │
  │ https://docs.python.org/3/license.html                                       │
  ╚─────────────────────────────────────────────────────────────────────────────*/
  #include "third_party/python/Include/dictobject.h"
  #include "third_party/python/Include/longobject.h"
  #include "third_party/python/Include/methodobject.h"
  #include "third_party/python/Include/modsupport.h"
  #include "third_party/python/Include/object.h"
  #include "third_party/python/Include/objimpl.h"
  #include "third_party/python/Include/typeslots.h"
  #include "third_party/python/Include/unicodeobject.h"
  #include "third_party/python/Include/yoink.h"
  /* clang-format off */
  
  PYTHON_PROVIDE("xxlimited");
  PYTHON_PROVIDE("xxlimited.Null");
  PYTHON_PROVIDE("xxlimited.Str");
  PYTHON_PROVIDE("xxlimited.Xxo");
  PYTHON_PROVIDE("xxlimited.error");
  PYTHON_PROVIDE("xxlimited.foo");
  PYTHON_PROVIDE("xxlimited.new");
  PYTHON_PROVIDE("xxlimited.roj");
  
  /* Use this file as a template to start implementing a module that
     also declares object types. All occurrences of 'Xxo' should be changed
     to something reasonable for your objects. After that, all other
     occurrences of 'xx' should be changed to something reasonable for your
     module. If your module is named foo your sourcefile should be named
     foomodule.c.
  
     You will probably want to delete all references to 'x_attr' and add
     your own types of attributes instead.  Maybe you want to name your
     local variables other than 'self'.  If your object type is needed in
     other files, you'll have to create a file "foobarobject.h"; see
     floatobject.h for an example. */
  
  /* Xxo objects */
  
  static PyObject *ErrorObject;
  
  typedef struct {
      PyObject_HEAD
      PyObject            *x_attr;        /* Attributes dictionary */
  } XxoObject;
  
  static PyObject *Xxo_Type;
  
  #define XxoObject_Check(v)      (Py_TYPE(v) == Xxo_Type)
  
  static XxoObject *
  newXxoObject(PyObject *arg)
  {
      XxoObject *self;
      self = PyObject_GC_New(XxoObject, (PyTypeObject*)Xxo_Type);
      if (self == NULL)
          return NULL;
      self->x_attr = NULL;
      return self;
  }
  
  /* Xxo methods */
  
  static int
  Xxo_traverse(XxoObject *self, visitproc visit, void *arg)
  {
      Py_VISIT(self->x_attr);
      return 0;
  }
  
  static void
  Xxo_finalize(XxoObject *self)
  {
      Py_CLEAR(self->x_attr);
  }
  
  static PyObject *
  Xxo_demo(XxoObject *self, PyObject *args)
  {
      PyObject *o = NULL;
      if (!PyArg_ParseTuple(args, "|O:demo", &o))
          return NULL;
      /* Test availability of fast type checks */
      if (o != NULL && PyUnicode_Check(o)) {
          Py_INCREF(o);
          return o;
      }
      Py_INCREF(Py_None);
      return Py_None;
  }
  
  static PyMethodDef Xxo_methods[] = {
      {"demo",            (PyCFunction)Xxo_demo,  METH_VARARGS,
          PyDoc_STR("demo() -> None")},
      {NULL,              NULL}           /* sentinel */
  };
  
  static PyObject *
  Xxo_getattro(XxoObject *self, PyObject *name)
  {
      if (self->x_attr != NULL) {
          PyObject *v = PyDict_GetItem(self->x_attr, name);
          if (v != NULL) {
              Py_INCREF(v);
              return v;
          }
      }
      return PyObject_GenericGetAttr((PyObject *)self, name);
  }
  
  static int
  Xxo_setattr(XxoObject *self, const char *name, PyObject *v)
  {
      if (self->x_attr == NULL) {
          self->x_attr = PyDict_New();
          if (self->x_attr == NULL)
              return -1;
      }
      if (v == NULL) {
          int rv = PyDict_DelItemString(self->x_attr, name);
          if (rv < 0)
              PyErr_SetString(PyExc_AttributeError,
                  "delete non-existing Xxo attribute");
          return rv;
      }
      else
          return PyDict_SetItemString(self->x_attr, name, v);
  }
  
  static PyType_Slot Xxo_Type_slots[] = {
      {Py_tp_doc, "The Xxo type"},
      {Py_tp_traverse, Xxo_traverse},
      {Py_tp_finalize, Xxo_finalize},
      {Py_tp_getattro, Xxo_getattro},
      {Py_tp_setattr, Xxo_setattr},
      {Py_tp_methods, Xxo_methods},
      {0, 0},
  };
  
  static PyType_Spec Xxo_Type_spec = {
      "xxlimited.Xxo",
      sizeof(XxoObject),
      0,
      Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC | Py_TPFLAGS_HAVE_FINALIZE,
      Xxo_Type_slots
  };
  
  /* --------------------------------------------------------------------- */
  
  /* Function of two integers returning integer */
  
  PyDoc_STRVAR(xx_foo_doc,
  "foo(i,j)\n\
  \n\
  Return the sum of i and j.");
  
  static PyObject *
  xx_foo(PyObject *self, PyObject *args)
  {
      long i, j;
      long res;
      if (!PyArg_ParseTuple(args, "ll:foo", &i, &j))
          return NULL;
      res = i+j; /* XXX Do something here */
      return PyLong_FromLong(res);
  }
  
  
  /* Function of no arguments returning new Xxo object */
  
  static PyObject *
  xx_new(PyObject *self, PyObject *args)
  {
      XxoObject *rv;
  
      if (!PyArg_ParseTuple(args, ":new"))
          return NULL;
      rv = newXxoObject(args);
      if (rv == NULL)
          return NULL;
      return (PyObject *)rv;
  }
  
  /* Test bad format character */
  
  static PyObject *
  xx_roj(PyObject *self, PyObject *args)
  {
      PyObject *a;
      long b;
      if (!PyArg_ParseTuple(args, "O#:roj", &a, &b))
          return NULL;
      Py_INCREF(Py_None);
      return Py_None;
  }
  
  
  /* ---------- */
  
  static PyType_Slot Str_Type_slots[] = {
      {Py_tp_base, NULL}, /* filled out in module init function */
      {0, 0},
  };
  
  static PyType_Spec Str_Type_spec = {
      "xxlimited.Str",
      0,
      0,
      Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
      Str_Type_slots
  };
  
  /* ---------- */
  
  static PyObject *
  null_richcompare(PyObject *self, PyObject *other, int op)
  {
      Py_RETURN_NOTIMPLEMENTED;
  }
  
  static PyType_Slot Null_Type_slots[] = {
      {Py_tp_base, NULL}, /* filled out in module init */
      {Py_tp_new, NULL},
      {Py_tp_richcompare, null_richcompare},
      {0, 0}
  };
  
  static PyType_Spec Null_Type_spec = {
      "xxlimited.Null",
      0,               /* basicsize */
      0,               /* itemsize */
      Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
      Null_Type_slots
  };
  
  /* ---------- */
  
  /* List of functions defined in the module */
  
  static PyMethodDef xx_methods[] = {
      {"roj",             xx_roj,         METH_VARARGS,
          PyDoc_STR("roj(a,b) -> None")},
      {"foo",             xx_foo,         METH_VARARGS,
          xx_foo_doc},
      {"new",             xx_new,         METH_VARARGS,
          PyDoc_STR("new() -> new Xx object")},
      {NULL,              NULL}           /* sentinel */
  };
  
  PyDoc_STRVAR(module_doc,
  "This is a template module just for instruction.");
  
  static int
  xx_modexec(PyObject *m)
  {
      PyObject *o;
  
      /* Due to cross platform compiler issues the slots must be filled
       * here. It's required for portability to Windows without requiring
       * C++. */
      Null_Type_slots[0].pfunc = &PyBaseObject_Type;
      Null_Type_slots[1].pfunc = PyType_GenericNew;
      Str_Type_slots[0].pfunc = &PyUnicode_Type;
  
      Xxo_Type = PyType_FromSpec(&Xxo_Type_spec);
      if (Xxo_Type == NULL)
          goto fail;
  
      /* Add some symbolic constants to the module */
      if (ErrorObject == NULL) {
          ErrorObject = PyErr_NewException("xxlimited.error", NULL, NULL);
          if (ErrorObject == NULL)
              goto fail;
      }
      Py_INCREF(ErrorObject);
      PyModule_AddObject(m, "error", ErrorObject);
  
      /* Add Xxo */
      o = PyType_FromSpec(&Xxo_Type_spec);
      if (o == NULL)
          goto fail;
      PyModule_AddObject(m, "Xxo", o);
  
      /* Add Str */
      o = PyType_FromSpec(&Str_Type_spec);
      if (o == NULL)
          goto fail;
      PyModule_AddObject(m, "Str", o);
  
      /* Add Null */
      o = PyType_FromSpec(&Null_Type_spec);
      if (o == NULL)
          goto fail;
      PyModule_AddObject(m, "Null", o);
      return 0;
   fail:
      Py_XDECREF(m);
      return -1;
  }
  
  
  static PyModuleDef_Slot xx_slots[] = {
      {Py_mod_exec, xx_modexec},
      {0, NULL}
  };
  
  static struct PyModuleDef xxmodule = {
      PyModuleDef_HEAD_INIT,
      "xxlimited",
      module_doc,
      0,
      xx_methods,
      xx_slots,
      NULL,
      NULL,
      NULL
  };
  
  /* Export function for the module (*must* be called PyInit_xx) */
  
  PyMODINIT_FUNC
  PyInit_xxlimited(void)
  {
      return PyModuleDef_Init(&xxmodule);
  }
  