Starts to implement sequence methods for RPNExpr

Starting with __len__
Next we have to implement token acces as a sequence in RPNExpr, but to do
this we have to implement a module allowing token access from python.

python_rpnexpr.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2020 Weber Yann
+ * Copyright (C) 2020,2023 Weber Yann
  * 
  * This file is part of pyrpn.
  * 
@@ -46,46 +46,25 @@ PyMemberDef RPNExpr_members[] = {
 	{NULL}
 };
 
+PySequenceMethods RPNExpr_seq_methods = {
+	.sq_length = rpnexpr_len,
+};
+
 PyTypeObject RPNExprType = {
 	PyVarObject_HEAD_INIT(NULL, 0)
-	"pyrpn.RPNExpr",                     /* tp_name */
-	sizeof(PyRPNExpr_t),                        /* tp_basicsize */
-	0,                                               /* tp_itemsize */
-	(destructor)rpnexpr_del, /* tp_dealloc */
-	0,                                               /* tp_print */
-	0,                                               /* tp_getattr */
-	0,                                               /* tp_setattr */
-	0,                                               /* tp_reserved */
-	rpnexpr_repr,                                    /* tp_repr */
-	0,                                               /* tp_as_number */
-	0,                                               /* tp_as_sequence */
-	0,                              /* tp_as_mapping */
-	0,                                               /* tp_hash  */
-	0,                                               /* tp_call */
-	rpnexpr_str,                                               /* tp_str */
-	0,                                               /* tp_getattro */
-	0,                                               /* tp_setattro */
-	0,                                               /* tp_as_buffer */
-	Py_TPFLAGS_DEFAULT |
-	Py_TPFLAGS_BASETYPE,   /* tp_flags */
-	"RPN expression evaluator",                /* tp_doc */
-	0,                                               /* tp_traverse */
-	0,                                               /* tp_clear */
-	0,                                               /* tp_richcompare */
-	0,                                               /* tp_weaklistoffset */
-	0,                                               /* tp_iter */
-	0,                                               /* tp_iternext */
-	RPNExpr_methods,                        /* tp_methods */
-	RPNExpr_members,                        /* tp_members */
-	0,                                               /* tp_getset */
-	0,                                               /* tp_base */
-	0,                                               /* tp_dict */
-	0,                                               /* tp_descr_get */
-	0,                                               /* tp_descr_set */
-	0,                                               /* tp_dictoffset */
-	rpnexpr_init,          /* tp_init */
-	0,                                               /* tp_alloc */
-	rpnexpr_new,                            /* tp_new */
+	.tp_name = "pyrpn.RPNExpr",
+	.tp_doc = "RPN expression evaluator",
+	.tp_basicsize = sizeof(PyRPNExpr_t),
+	.tp_itemsize = 0,
+	.tp_del = rpnexpr_del,
+	.tp_repr = rpnexpr_repr,
+	.tp_str = rpnexpr_str,
+	.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
+	.tp_methods = RPNExpr_methods,
+	.tp_as_sequence = &RPNExpr_seq_methods,
+	.tp_members = RPNExpr_members,
+	.tp_init = rpnexpr_init,
+	.tp_new = rpnexpr_new,
 };
 
 PyObject* rpnexpr_new(PyTypeObject *subtype, PyObject *args, PyObject* kwds)
@@ -529,6 +508,13 @@ err:
 }
 
 
+Py_ssize_t rpnexpr_len(PyObject *self)
+{
+	PyRPNExpr_t *expr_self = (PyRPNExpr_t*)self;
+	return (Py_ssize_t)expr_self->rpn->toks.tokens_sz;
+}
+
+
 PyObject* rpnexpr_eval(PyObject* self, PyObject** argv, Py_ssize_t argc)
 {
 	PyRPNExpr_t *expr_self;
@@ -844,6 +830,7 @@ int rpnexpr_pyobj_to_mutation_params(PyObject* py_params, rpn_mutation_params_t
 		PyErr_SetString(PyExc_ValueError, "Bad value for .weight_add_elt field");
 		return -1;
 	}
+	rpn_mutation_init_params(params);
 	return 0;
 }
 

python_rpnexpr.h

@@ -41,6 +41,9 @@
  * @ingroup python_type
  *
  * This file is the header of the RPNExpr Python class
+ *
+ * @todo implements tp_as_sequence in order to give access to tokens from
+ * expr. To do this we have to implement a python module representing tokens.
  */
 
 /**@brief RPNExpr Python class methods list
@@ -144,6 +147,11 @@ PyObject* rpnexpr_setstate(PyObject *cls, PyObject *state);
  */
 PyObject* rpnexpr_copy(PyObject *cls, PyObject *noargs);
 
+/**@brief RPNExpr.__len__() method
+ * @return A integer with the number of tokens in expression
+ */
+Py_ssize_t rpnexpr_len(PyObject *self);
+
 /**@brief Eval an RPN expression given arguments and return the
  * value
  * @param self RPNExpr instance