Factor out base update in a separate helper

ilevkivskyi · ilevkivskyi · commit 41fa7e9ce186 · 2017-11-11T10:01:19.000+01:00
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
@@ -46,39 +46,15 @@ _Py_IDENTIFIER(stderr);
 
 #include "clinic/bltinmodule.c.h"
 
-/* AC: cannot convert yet, waiting for *args support */
-static PyObject *
-builtin___build_class__(PyObject *self, PyObject **args, Py_ssize_t nargs,
-                        PyObject *kwnames)
+static PyObject*
+update_bases(PyObject* bases, PyObject** args, int nargs, int* modified_bases)
 {
-    PyObject *func, *name, *bases, *mkw, *meta, *winner, *prep, *ns, *new_bases;
-    PyObject *cls = NULL, *cell = NULL;
-    PyObject *base_types;
-    int isclass = 0;   /* initialize to prevent gcc warning */
-    int i, modified_bases = 0;
-
-    if (nargs < 2) {
-        PyErr_SetString(PyExc_TypeError,
-                        "__build_class__: not enough arguments");
-        return NULL;
-    }
-    func = args[0];   /* Better be callable */
-    if (!PyFunction_Check(func)) {
-        PyErr_SetString(PyExc_TypeError,
-                        "__build_class__: func must be a function");
-        return NULL;
-    }
-    name = args[1];
-    if (!PyUnicode_Check(name)) {
-        PyErr_SetString(PyExc_TypeError,
-                        "__build_class__: name is not a string");
-        return NULL;
-    }
-
-    bases = _PyStack_AsTupleSlice(args, nargs, 2, nargs);
-    if (bases == NULL)
-        return NULL;
+    int i, ind, tot_nones;
+    PyObject *new_bases;
+    assert(PyTuple_Check(bases));
 
+    /* We have a separate cycle to calculate replacements with the idea that
+       most cases we just scroll quickly though it and return original bases */
     for (i = 2; i < nargs; i++){
         PyObject *base, *new_base, *new_base_meth;
         PyObject* stack[1];
@@ -92,7 +68,6 @@ builtin___build_class__(PyObject *self, PyObject **args, Py_ssize_t nargs,
                 PyErr_Clear();
             }
             else {
-                Py_DECREF(bases);
                 return NULL;
             }
         }
@@ -101,32 +76,31 @@ builtin___build_class__(PyObject *self, PyObject **args, Py_ssize_t nargs,
                 PyErr_Format(PyExc_TypeError,
                              "attribute of type '%.200s' is not callable",
                              Py_TYPE(new_base_meth)->tp_name);
-                Py_DECREF(bases);
                 return NULL;
             }
             stack[0] = bases;
             new_base = _PyObject_FastCall(new_base_meth, stack, 1);
             if (new_base == NULL){
-                Py_DECREF(bases);
                 return NULL;
             }
             Py_INCREF(new_base);
             args[i] = new_base;
-            modified_bases = 1;
+            *modified_bases = 1;
         }
     }
 
-    if (modified_bases){
-        int ind, tot_nones = 0;
+    if (*modified_bases){
+        /* Find out have many bases wants to be removed to pre-allocate
+           the tuple for new bases */
+        tot_nones = 0;
         for (i = 2; i < nargs; i++){
             if (args[i] == Py_None){
                 tot_nones++;
             }
         }
-
-        ind = 0;
-        /* Remove all None's from base classes */
         new_bases = PyTuple_New(nargs - 2 - tot_nones);
+        /* Remove all None's from base classes */
+        ind = 0;
         for (i = 2; i < nargs; i++){
             PyObject* base;
             base = args[i];
@@ -136,7 +110,54 @@ builtin___build_class__(PyObject *self, PyObject **args, Py_ssize_t nargs,
                 ind++;
             }
         }
+        return new_bases;
+    }
+    else{
+        return bases;
+    }
+}
+
+
+/* AC: cannot convert yet, waiting for *args support */
+static PyObject *
+builtin___build_class__(PyObject *self, PyObject **args, Py_ssize_t nargs,
+                        PyObject *kwnames)
+{
+    PyObject *func, *name, *bases, *mkw, *meta, *winner, *prep, *ns;
+    PyObject *new_bases, *old_bases = NULL;
+    PyObject *cls = NULL, *cell = NULL;
+    int isclass = 0;   /* initialize to prevent gcc warning */
+    int modified_bases = 0;
+
+    if (nargs < 2) {
+        PyErr_SetString(PyExc_TypeError,
+                        "__build_class__: not enough arguments");
+        return NULL;
+    }
+    func = args[0];   /* Better be callable */
+    if (!PyFunction_Check(func)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "__build_class__: func must be a function");
+        return NULL;
+    }
+    name = args[1];
+    if (!PyUnicode_Check(name)) {
+        PyErr_SetString(PyExc_TypeError,
+                        "__build_class__: name is not a string");
+        return NULL;
+    }
+
+    bases = _PyStack_AsTupleSlice(args, nargs, 2, nargs);
+    if (bases == NULL)
+        return NULL;
+
+    new_bases = update_bases(bases, args, nargs, &modified_bases);
+    if (new_bases == NULL){
         Py_DECREF(bases);
+        return NULL;
+    }
+    else{
+        old_bases = bases;
         bases = new_bases;
     }
 
@@ -233,8 +254,7 @@ builtin___build_class__(PyObject *self, PyObject **args, Py_ssize_t nargs,
                              PyFunction_GET_CLOSURE(func));
     if (cell != NULL) {
         if (modified_bases){
-            base_types = _PyStack_AsTupleSlice(args, nargs, 2, nargs);
-            PyMapping_SetItemString(ns, "__orig_bases__", base_types);
+            PyMapping_SetItemString(ns, "__orig_bases__", old_bases);
         }
         PyObject *margs[3] = {name, bases, ns};
         cls = _PyObject_FastCallDict(meta, margs, 3, mkw);
