Add PyDict_GetItemRef()

Author: vstinner

docs/api.rst

@@ -27,13 +27,17 @@ Latest version of the header file:
 Python 3.13
 -----------
 
-.. c:function:: PyObject* PyImport_AddModuleRef(const char *name)
+.. c:function:: int PyDict_GetItemRef(PyObject *p, PyObject *key, PyObject **result)
 
-   See `PyImport_AddModuleRef() documentation <https://docs.python.org/dev/c-api/import.html#c.PyImport_AddModuleRef>`__.
+   See `PyDict_GetItemRef() documentation <https://docs.python.org/dev/c-api/dict.html#c.PyDict_GetItemRef>`__.
 
-.. c:function:: int PyWeakref_GetRef(PyObject *ref, PyObject **pobj)
+.. c:function:: int PyDict_GetItemStringRef(PyObject *p, const char *key, PyObject **result)
 
-   See `PyWeakref_GetRef() documentation <https://docs.python.org/dev/c-api/weakref.html#c.PyWeakref_GetRef>`__.
+   See `PyDict_GetItemStringRef() documentation <https://docs.python.org/dev/c-api/dict.html#c.PyDict_GetItemStringRef>`__.
+
+.. c:function:: PyObject* PyImport_AddModuleRef(const char *name)
+
+   See `PyImport_AddModuleRef() documentation <https://docs.python.org/dev/c-api/import.html#c.PyImport_AddModuleRef>`__.
 
 .. c:function:: int PyObject_GetOptionalAttr(PyObject *obj, PyObject *attr_name, PyObject **result)
 
@@ -55,6 +59,10 @@ Python 3.13
 
    See `PyModule_Add() documentation <https://docs.python.org/dev/c-api/module.html#c.PyModule_Add>`__.
 
+.. c:function:: int PyWeakref_GetRef(PyObject *ref, PyObject **pobj)
+
+   See `PyWeakref_GetRef() documentation <https://docs.python.org/dev/c-api/weakref.html#c.PyWeakref_GetRef>`__.
+
 
 Python 3.12
 -----------

docs/changelog.rst

@@ -1,6 +1,7 @@
 Changelog
 =========
 
+* 2023-07-21: Add ``PyDict_GetItemRef()`` function.
 * 2023-07-18: Add ``PyModule_Add()`` function.
 * 2023-07-12: Add ``PyObject_GetOptionalAttr()``,
   ``PyObject_GetOptionalAttrString()``,

docs/users.rst

@@ -38,11 +38,10 @@ Examples of projects using pythoncapi_compat.h
   (`commit <https://github.com/sergey-dryabzhinsky/python-zstd/commit/8aa6d7a4b250e1f0a4e27b4107c39dc516c87f96>`__)
 * `hollerith <https://github.com/pyansys/hollerith/>`_
   ``src/writer.c`` uses ``PyObject_CallOneArg() and other Python 3.9 apis``
-   (`pythoncapi_compat.h copy
+  (`pythoncapi_compat.h copy
   <https://github.com/pyansys/hollerith/blob/main/src/pythoncapi_compat.h>`__)
 
 
-
 Projects not using pythoncapi_compat.h
 ======================================
 

pythoncapi_compat.h

@@ -258,7 +258,7 @@ PyFrame_GetVar(PyFrameObject *frame, PyObject *name)
 #if PY_VERSION_HEX >= 0x03000000
     value = PyDict_GetItemWithError(locals, name);
 #else
-    value = PyDict_GetItem(locals, name);
+    value = _PyDict_GetItemWithError(locals, name);
 #endif
     Py_DECREF(locals);
 
@@ -791,6 +791,49 @@ PyMapping_GetOptionalItemString(PyObject *obj, const char *key, PyObject **resul
 #endif
 
 
+// gh-106004 added PyDict_GetItemRef() and PyDict_GetItemStringRef()
+// to Python 3.13.0a1
+#if PY_VERSION_HEX < 0x030D00A1
+PYCAPI_COMPAT_STATIC_INLINE(int)
+PyDict_GetItemRef(PyObject *mp, PyObject *key, PyObject **result)
+{
+#if PY_VERSION_HEX >= 0x03000000
+    PyObject *item = PyDict_GetItemWithError(mp, key);
+#else
+    PyObject *item = _PyDict_GetItemWithError(mp, key);
+#endif
+    if (item != NULL) {
+        *result = Py_NewRef(item);
+        return 1;  // found
+    }
+    if (!PyErr_Occurred()) {
+        *result = NULL;
+        return 0;  // not found
+    }
+    *result = NULL;
+    return -1;
+}
+
+PYCAPI_COMPAT_STATIC_INLINE(int)
+PyDict_GetItemStringRef(PyObject *mp, const char *key, PyObject **result)
+{
+    int res;
+#if PY_VERSION_HEX >= 0x03000000
+    PyObject *key_obj = PyUnicode_FromString(key);
+#else
+    PyObject *key_obj = PyString_FromString(key);
+#endif
+    if (key_obj == NULL) {
+        *result = NULL;
+        return -1;
+    }
+    res = PyDict_GetItemRef(mp, key_obj, result);
+    Py_DECREF(key_obj);
+    return res;
+}
+#endif
+
+
 // gh-106307 added PyModule_Add() to Python 3.13.0a1
 #if PY_VERSION_HEX < 0x030D00A1
 PYCAPI_COMPAT_STATIC_INLINE(int)

tests/test_pythoncapi_compat_cext.c

@@ -1086,6 +1086,113 @@ test_getitem(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
 }
 
 
+static PyObject *
+test_dict_getitemref(PyObject *Py_UNUSED(module), PyObject *Py_UNUSED(args))
+{
+    assert(!PyErr_Occurred());
+
+    PyObject *dict = NULL, *key = NULL, *missing_key = NULL, *value = NULL;
+    PyObject *invalid_key = NULL;
+    PyObject *invalid_dict = NULL;
+    PyObject *get_value = NULL;
+    int res;
+
+    // test PyDict_New()
+    dict = PyDict_New();
+    if (dict == NULL) {
+        goto error;
+    }
+
+    key = PyUnicode_FromString("key");
+    if (key == NULL) {
+        goto error;
+    }
+
+    missing_key = PyUnicode_FromString("missing_key");
+    if (missing_key == NULL) {
+        goto error;
+    }
+
+    value = PyUnicode_FromString("value");
+    if (value == NULL) {
+        goto error;
+    }
+
+    res = PyDict_SetItemString(dict, "key", value);
+    if (res < 0) {
+        goto error;
+    }
+    assert(res == 0);
+
+    // test PyDict_GetItemRef(), key is present
+    get_value = Py_Ellipsis;  // marker value
+    assert(PyDict_GetItemRef(dict, key, &get_value) == 1);
+    assert(get_value == value);
+    Py_DECREF(get_value);
+
+    // test PyDict_GetItemStringRef(), key is present
+    get_value = Py_Ellipsis;  // marker value
+    assert(PyDict_GetItemStringRef(dict, "key", &get_value) == 1);
+    assert(get_value == value);
+    Py_DECREF(get_value);
+
+    // test PyDict_GetItemRef(), missing key
+    get_value = Py_Ellipsis;  // marker value
+    assert(PyDict_GetItemRef(dict, missing_key, &get_value) == 0);
+    assert(!PyErr_Occurred());
+    assert(get_value == NULL);
+
+    // test PyDict_GetItemStringRef(), missing key
+    get_value = Py_Ellipsis;  // marker value
+    assert(PyDict_GetItemStringRef(dict, "missing_key", &get_value) == 0);
+    assert(!PyErr_Occurred());
+    assert(get_value == NULL);
+
+    // test PyDict_GetItemRef(), invalid dict
+    invalid_dict = key;  // borrowed reference
+    get_value = Py_Ellipsis;  // marker value
+    assert(PyDict_GetItemRef(invalid_dict, key, &get_value) == -1);
+    assert(PyErr_ExceptionMatches(PyExc_SystemError));
+    PyErr_Clear();
+    assert(get_value == NULL);
+
+    // test PyDict_GetItemStringRef(), invalid dict
+    get_value = Py_Ellipsis;  // marker value
+    assert(PyDict_GetItemStringRef(invalid_dict, "key", &get_value) == -1);
+    assert(PyErr_ExceptionMatches(PyExc_SystemError));
+    PyErr_Clear();
+    assert(get_value == NULL);
+
+    invalid_key = PyList_New(0);  // not hashable key
+    if (invalid_key == NULL) {
+        goto error;
+    }
+
+    // test PyDict_GetItemRef(), invalid key
+    get_value = Py_Ellipsis;  // marker value
+    assert(PyDict_GetItemRef(dict, invalid_key, &get_value) == -1);
+    assert(PyErr_ExceptionMatches(PyExc_TypeError));
+    PyErr_Clear();
+    assert(get_value == NULL);
+
+    Py_DECREF(dict);
+    Py_DECREF(key);
+    Py_DECREF(missing_key);
+    Py_DECREF(value);
+    Py_DECREF(invalid_key);
+
+    Py_RETURN_NONE;
+
+error:
+    Py_XDECREF(dict);
+    Py_XDECREF(key);
+    Py_XDECREF(missing_key);
+    Py_XDECREF(value);
+    Py_XDECREF(invalid_key);
+    return NULL;
+}
+
+
 static struct PyMethodDef methods[] = {
     {"test_object", test_object, METH_NOARGS, _Py_NULL},
     {"test_py_is", test_py_is, METH_NOARGS, _Py_NULL},
@@ -1110,6 +1217,7 @@ static struct PyMethodDef methods[] = {
     {"test_vectorcall", test_vectorcall, METH_NOARGS, _Py_NULL},
     {"test_getattr", test_getattr, METH_NOARGS, _Py_NULL},
     {"test_getitem", test_getitem, METH_NOARGS, _Py_NULL},
+    {"test_dict_getitemref", test_dict_getitemref, METH_NOARGS, _Py_NULL},
     {_Py_NULL, _Py_NULL, 0, _Py_NULL}
 };