Implement introspection with __signature__ package

The signature module was turned into a package under
'PySide2/support/signature'. The package is completely isolated
so that nothing is leaking into the normal import machinery.

The package is also not initialized unless a __signature__ attribute
is accessed. The only change to Python during a PySide run is
the existence of the __signature__ attribute.

As a side effect, all tests run at the same speed as before
this extension.

The module does not actively import PySide modules. Instead,
it inspects sys.modules and reloads its mapping.py if needed.

Example usage:

>>> PySide2.QtWidgets.QGraphicsAnchorLayout.addAnchors.__signature__
>>> PySide2.QtWidgets.QGraphicsAnchorLayout.__signature__

The module has been thoroughly tested on macOS.
I consider this ready.

Task-number: PYSIDE-510
Change-Id: Ibb231a7fbb4ccc1a7249df55e3881a4e21a19c0d
Reviewed-by: Christian Tismer <tismer@stackless.com>

2 files changed, 151 insertions, 0 deletions

diff --git a/sources/pyside2/tests/pysidetest/CMakeLists.txt b/sources/pyside2/tests/pysidetest/CMakeLists.txt
index b5fcb8d12..d46498f77 100644
--- a/sources/pyside2/tests/pysidetest/CMakeLists.txt
+++ b/sources/pyside2/tests/pysidetest/CMakeLists.txt
@@ -123,3 +123,4 @@ PYSIDE_TEST(utils_test.py)
 PYSIDE_TEST(mixin_signal_slots_test.py)
 PYSIDE_TEST(signal_slot_warning.py)
 PYSIDE_TEST(all_modules_load_test.py)
+PYSIDE_TEST(signature_test.py)
diff --git a/sources/pyside2/tests/pysidetest/signature_test.py b/sources/pyside2/tests/pysidetest/signature_test.py
new file mode 100644
index 000000000..7fa0ab6fc
--- /dev/null
+++ b/sources/pyside2/tests/pysidetest/signature_test.py
@@ -0,0 +1,150 @@
+#############################################################################
+##
+## Copyright (C) 2017 The Qt Company Ltd.
+## Contact: https://www.qt.io/licensing/
+##
+## This file is part of PySide2.
+##
+## $QT_BEGIN_LICENSE:LGPL$
+## Commercial License Usage
+## Licensees holding valid commercial Qt licenses may use this file in
+## accordance with the commercial license agreement provided with the
+## Software or, alternatively, in accordance with the terms contained in
+## a written agreement between you and The Qt Company. For licensing terms
+## and conditions see https://www.qt.io/terms-conditions. For further
+## information use the contact form at https://www.qt.io/contact-us.
+##
+## GNU Lesser General Public License Usage
+## Alternatively, this file may be used under the terms of the GNU Lesser
+## General Public License version 3 as published by the Free Software
+## Foundation and appearing in the file LICENSE.LGPL3 included in the
+## packaging of this file. Please review the following information to
+## ensure the GNU Lesser General Public License version 3 requirements
+## will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+##
+## GNU General Public License Usage
+## Alternatively, this file may be used under the terms of the GNU
+## General Public License version 2.0 or (at your option) the GNU General
+## Public license version 3 or any later version approved by the KDE Free
+## Qt Foundation. The licenses are as published by the Free Software
+## Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+## included in the packaging of this file. Please review the following
+## information to ensure the GNU General Public License requirements will
+## be met: https://www.gnu.org/licenses/gpl-2.0.html and
+## https://www.gnu.org/licenses/gpl-3.0.html.
+##
+## $QT_END_LICENSE$
+##
+#############################################################################
+
+from __future__ import print_function
+
+import sys
+import os
+import unittest
+from collections import OrderedDict
+from pprint import pprint
+import PySide2
+from PySide2 import *
+
+"""
+This test shows that we have over 14500 signatures,
+and that they all can be created.
+"""
+
+all_modules = list("PySide2." + x for x in PySide2.__all__)
+
+from PySide2.support.signature import parser, inspect
+parser._BREAK_ON_ERROR = True
+
+_do_print = True if os.isatty(sys.stdout.fileno()) else False
+
+def dprint(*args, **kw):
+    if _do_print:
+        print(*args, **kw)
+
+def enum_module(mod_name):
+    count = 0
+    module = sys.modules[mod_name]
+    dprint()
+    dprint("Module", mod_name)
+    members = inspect.getmembers(module, inspect.isclass)
+    for class_name, klass in members:
+        signature = getattr(klass, '__signature__', None)
+        dprint()
+        # class_members = inspect.getmembers(klass)
+        # gives us also the inherited things.
+        dprint("  class {}:".format(class_name))
+        if signature is None:
+            pass # initialization not called?
+        elif isinstance(signature, list):
+            dprint("    with overloading():")
+            for overload in signature:
+                dprint("      def __init__" + str(overload))
+        else:
+            dprint("    def __init__" + str(signature))
+        count += 1
+        class_members = list(klass.__dict__.items())
+        for func_name, func in class_members:
+            signature = getattr(func, '__signature__', None)
+            if signature is not None:
+                if isinstance(signature, list):
+                    dprint("    with overloading():")
+                    for overload in signature:
+                        dprint("      def", func_name + str(overload))
+                else:
+                    dprint("    def", func_name + str(signature))
+                count += 1
+    return count
+
+def enum_all():
+    result = OrderedDict()
+    total = 0
+    for mod_name in all_modules:
+        result[mod_name] = enum_module(mod_name)
+        total += result[mod_name]
+    pprint(result if sys.version_info >= (3,) else list(result.items()))
+    print("Total", total)
+    return result
+
+
+class PySideSignatureTest(unittest.TestCase):
+    def testAllSignaturesCanBuild(self):
+        # This test touches all attributes
+        result = enum_all()
+        # We omit the number of functions test. This is too vague.
+        for mod_name, count in result.items():
+            pass #self.assertGreaterEqual(count, ref_result[mod_name])
+
+    def testSignatureExist(self):
+        t1 = type(PySide2.QtCore.QObject.children.__signature__)
+        self.assertEqual(t1, inspect.Signature)
+        t2 = type(PySide2.QtCore.QObject.__dict__["children"].__signature__)
+        self.assertEqual(t2, t1)
+        obj = PySide2.QtWidgets.QApplication.palette
+        t3 = type(obj.__signature__)
+        self.assertEqual(t3, list)
+        self.assertEqual(len(obj.__signature__), 3)
+        for thing in obj.__signature__:
+            self.assertEqual(type(thing), inspect.Signature)
+        sm = PySide2.QtWidgets.QApplication.__dict__["palette"]
+        self.assertFalse(callable(sm))
+        self.assertEqual(sm.__func__, obj)
+        self.assertTrue(hasattr(sm, "__signature__") and
+                        sm.__signature__ is not None)
+
+    def testSignatureIsCached(self):
+        # see if we get the same object
+        ob1 = PySide2.QtCore.QObject.children.__signature__
+        ob2 = PySide2.QtCore.QObject.children.__signature__
+        self.assertTrue(ob1 is ob2)
+        # same with multi signature
+        ob1 = PySide2.QtWidgets.QApplication.palette.__signature__
+        ob2 = PySide2.QtWidgets.QApplication.palette.__signature__
+        self.assertTrue(ob1 is ob2)
+
+    def testModuleIsInitialized(self):
+        assert QtWidgets.QApplication.__signature__ is not None
+
+if __name__ == "__main__":
+    unittest.main()