Support pickling of Qt Enum objects

Pickling for types exists in most cases.

Pickling of Qt Enum objects works fine.

Pickling of Qt Enum types is supported, but does not work
because the builtin type pickling intercepts and then fails..

This problem is now solved because PySide supports
now __qualname__.

So pickling of nested types works now without any extra
code in Python 3. Python 2 is not supported since it would
require too strange patches to Python itself.

Fixes: PYSIDE-15
Task-number: PYSIDE-1286
Change-Id: I346bde07a63afcf2555a3324fcca04efe25e704a
Reviewed-by: Christian Tismer <tismer@stackless.com>

6 files changed, 183 insertions, 1 deletions

diff --git a/sources/pyside2/tests/QtCore/qenum_test.py b/sources/pyside2/tests/QtCore/qenum_test.py
index dd91d1581..ed58f4f20 100644
--- a/sources/pyside2/tests/QtCore/qenum_test.py
+++ b/sources/pyside2/tests/QtCore/qenum_test.py
@@ -32,13 +32,15 @@
 
 import os
 import sys
+import pickle
 import unittest
 
 sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 from init_paths import init_test_paths
 init_test_paths(False)
 
-from PySide2.QtCore import *
+from PySide2.QtCore import Qt, QIODevice
+
 
 class TestEnum(unittest.TestCase):
 
@@ -73,6 +75,7 @@ class TestEnum(unittest.TestCase):
         with self.assertRaises(TypeError):
             a = k*2.0
 
+
 class TestQFlags(unittest.TestCase):
     def testToItn(self):
         om = QIODevice.NotOpen
@@ -94,5 +97,33 @@ class TestQFlags(unittest.TestCase):
         except:
             pass
 
+
+# PYSIDE-15: Pickling of enums
+class TestEnumPickling(unittest.TestCase):
+    def testPickleEnum(self):
+
+        # Pickling of enums with different depth works.
+        ret = pickle.loads(pickle.dumps(QIODevice.Append))
+        self.assertEqual(ret, QIODevice.Append)
+
+        ret = pickle.loads(pickle.dumps(Qt.Key.Key_Asterisk))
+        self.assertEqual(ret, Qt.Key.Key_Asterisk)
+        self.assertEqual(ret, Qt.Key(42))
+
+        # We can also pickle the whole enum class (built in):
+        ret = pickle.loads(pickle.dumps(QIODevice))
+
+        # This works also with nested classes for Python 3, after we
+        # introduced the correct __qualname__ attribute.
+
+        # Note: For Python 2, we would need quite strange patches.
+        func = lambda: pickle.loads(pickle.dumps(Qt.Key))
+        if sys.version_info[0] < 3:
+            with self.assertRaises(pickle.PicklingError):
+                func()
+        else:
+            func()
+
+
 if __name__ == '__main__':
     unittest.main()
diff --git a/sources/shiboken2/libshiboken/pep384impl.cpp b/sources/shiboken2/libshiboken/pep384impl.cpp
index c04848eb3..6405d777a 100644
--- a/sources/shiboken2/libshiboken/pep384impl.cpp
+++ b/sources/shiboken2/libshiboken/pep384impl.cpp
@@ -638,6 +638,38 @@ PepType_GetNameStr(PyTypeObject *type)
 
 /*****************************************************************************
  *
+ * Newly introduced convenience functions
+ *
+ */
+#if PY_VERSION_HEX < 0x03070000
+
+PyObject *
+PyImport_GetModule(PyObject *name)
+{
+    PyObject *m;
+    PyObject *modules = PyImport_GetModuleDict();
+    if (modules == NULL) {
+        PyErr_SetString(PyExc_RuntimeError, "unable to get sys.modules");
+        return NULL;
+    }
+    Py_INCREF(modules);
+    if (PyDict_CheckExact(modules)) {
+        m = PyDict_GetItemWithError(modules, name);  /* borrowed */
+        Py_XINCREF(m);
+    }
+    else {
+        m = PyObject_GetItem(modules, name);
+        if (m == NULL && PyErr_ExceptionMatches(PyExc_KeyError)) {
+            PyErr_Clear();
+        }
+    }
+    Py_DECREF(modules);
+    return m;
+}
+
+#endif // PY_VERSION_HEX < 0x03070000
+/*****************************************************************************
+ *
  * Extra support for name mangling
  *
  */
diff --git a/sources/shiboken2/libshiboken/pep384impl.h b/sources/shiboken2/libshiboken/pep384impl.h
index e735095e8..c180a06c1 100644
--- a/sources/shiboken2/libshiboken/pep384impl.h
+++ b/sources/shiboken2/libshiboken/pep384impl.h
@@ -523,6 +523,15 @@ extern LIBSHIBOKEN_API PyTypeObject *PepMethodDescr_TypePtr;
 
 /*****************************************************************************
  *
+ * Newly introduced convenience functions
+ *
+ */
+#if PY_VERSION_HEX < 0x03070000
+LIBSHIBOKEN_API PyObject *PyImport_GetModule(PyObject *name);
+#endif // PY_VERSION_HEX < 0x03070000
+
+/*****************************************************************************
+ *
  * Runtime support for Python 3.8 incompatibilities
  *
  */
diff --git a/sources/shiboken2/libshiboken/sbkenum.cpp b/sources/shiboken2/libshiboken/sbkenum.cpp
index 2b80da112..5b9718738 100644
--- a/sources/shiboken2/libshiboken/sbkenum.cpp
+++ b/sources/shiboken2/libshiboken/sbkenum.cpp
@@ -361,6 +361,107 @@ PyObject *SbkEnumTypeTpNew(PyTypeObject *metatype, PyObject *args, PyObject *kwd
 
 } // extern "C"
 
+///////////////////////////////////////////////////////////////
+//
+// PYSIDE-15: Pickling Support for Qt Enum objects
+//            This works very well and fixes the issue.
+//
+extern "C" {
+
+static void init_enum();  // forward
+
+static PyObject *enum_unpickler = nullptr;
+
+// Pickling: reduce the Qt Enum object
+static PyObject *enum___reduce__(PyObject *obj)
+{
+    init_enum();
+    return Py_BuildValue("O(Ni)",
+                         enum_unpickler,
+                         Py_BuildValue("s", Py_TYPE(obj)->tp_name),
+                         PyInt_AS_LONG(obj));
+}
+
+} // extern "C"
+
+namespace Shiboken { namespace Enum {
+
+// Unpickling: rebuild the Qt Enum object
+PyObject *unpickleEnum(PyObject *enum_class_name, PyObject *value)
+{
+    Shiboken::AutoDecRef parts(PyObject_CallMethod(enum_class_name,
+        const_cast<char *>("split"), const_cast<char *>("s"), "."));
+    if (parts.isNull())
+        return nullptr;
+    PyObject *top_name = PyList_GetItem(parts, 0); // borrowed ref
+    if (top_name == nullptr)
+        return nullptr;
+    PyObject *module = PyImport_GetModule(top_name);
+    if (module == nullptr) {
+        PyErr_Format(PyExc_ImportError, "could not import module %.200s",
+            Shiboken::String::toCString(top_name));
+        return nullptr;
+    }
+    Shiboken::AutoDecRef cur_thing(module);
+    int len = PyList_Size(parts);
+    for (int idx = 1; idx < len; ++idx) {
+        PyObject *name = PyList_GetItem(parts, idx); // borrowed ref
+        PyObject *thing = PyObject_GetAttr(cur_thing, name);
+        if (thing == nullptr) {
+            PyErr_Format(PyExc_ImportError, "could not import Qt Enum type %.200s",
+                Shiboken::String::toCString(enum_class_name));
+            return nullptr;
+        }
+        cur_thing.reset(thing);
+    }
+    PyObject *klass = cur_thing;
+    return PyObject_CallFunctionObjArgs(klass, value, nullptr);
+}
+
+} // namespace Enum
+} // namespace Shiboken
+
+extern "C" {
+
+// Initialization
+static bool _init_enum()
+{
+    static PyObject *shiboken_name = Py_BuildValue("s", "shiboken2");
+    if (shiboken_name == nullptr)
+        return false;
+    Shiboken::AutoDecRef shibo(PyImport_GetModule(shiboken_name));
+    if (shibo.isNull())
+        return false;
+    Shiboken::AutoDecRef sub(PyObject_GetAttr(shibo, shiboken_name));
+    PyObject *mod = sub.object();
+    if (mod == nullptr) {
+        // We are in the build dir and already in shiboken.
+        PyErr_Clear();
+        mod = shibo.object();
+    }
+    enum_unpickler = PyObject_GetAttrString(mod, "_unpickle_enum");
+    if (enum_unpickler == nullptr)
+        return false;
+    return true;
+}
+
+static void init_enum()
+{
+    if (!(enum_unpickler || _init_enum()))
+        Py_FatalError("could not load enum helper functions");
+}
+
+static PyMethodDef SbkEnumObject_Methods[] = {
+    {const_cast<char *>("__reduce__"), reinterpret_cast<PyCFunction>(enum___reduce__),
+        METH_NOARGS, nullptr},
+    {nullptr, nullptr, 0, nullptr} // Sentinel
+};
+
+} // extern "C"
+
+//
+///////////////////////////////////////////////////////////////
+
 namespace Shiboken {
 
 class DeclaredEnumTypes
@@ -521,6 +622,7 @@ static PyType_Slot SbkNewType_slots[] = {
     {Py_tp_repr, (void *)SbkEnumObject_repr},
     {Py_tp_str, (void *)SbkEnumObject_repr},
     {Py_tp_getset, (void *)SbkEnumGetSetList},
+    {Py_tp_methods, (void *)SbkEnumObject_Methods},
     {Py_tp_new, (void *)SbkEnum_tp_new},
     {Py_nb_add, (void *)enum_add},
     {Py_nb_subtract, (void *)enum_subtract},
diff --git a/sources/shiboken2/libshiboken/sbkenum.h b/sources/shiboken2/libshiboken/sbkenum.h
index 759d72636..c294c17d9 100644
--- a/sources/shiboken2/libshiboken/sbkenum.h
+++ b/sources/shiboken2/libshiboken/sbkenum.h
@@ -114,6 +114,8 @@ namespace Enum
     LIBSHIBOKEN_API void setTypeConverter(PyTypeObject *enumType, SbkConverter *converter);
     /// Returns the converter assigned to the enum \p type.
     LIBSHIBOKEN_API SbkConverter *getTypeConverter(PyTypeObject *enumType);
+
+    LIBSHIBOKEN_API PyObject *unpickleEnum(PyObject *, PyObject *);
 }
 
 } // namespace Shiboken
diff --git a/sources/shiboken2/shibokenmodule/typesystem_shiboken.xml b/sources/shiboken2/shibokenmodule/typesystem_shiboken.xml
index bdb0c9338..3eba557fb 100644
--- a/sources/shiboken2/shibokenmodule/typesystem_shiboken.xml
+++ b/sources/shiboken2/shibokenmodule/typesystem_shiboken.xml
@@ -103,6 +103,12 @@
         </inject-code>
     </add-function>
 
+    <add-function signature="_unpickle_enum(PyObject*, PyObject*)" return-type="PyObject*">
+        <inject-code>
+            %PYARG_0 = Shiboken::Enum::unpickleEnum(%1, %2);
+        </inject-code>
+    </add-function>
+
     <extra-includes>
         <include file-name="sbkversion.h" location="local"/>
         <include file-name="voidptr.h" location="local"/>