Enable support for pattern matching

immutables/_map.c

@@ -3414,7 +3414,11 @@ PyTypeObject _Map_Type = {
     .tp_iter = (getiterfunc)map_tp_iter,
     .tp_dealloc = (destructor)map_tp_dealloc,
     .tp_getattro = PyObject_GenericGetAttr,
-    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,
+    .tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC
+    #ifdef Py_TPFLAGS_MAPPING
+        | Py_TPFLAGS_MAPPING
+    #endif
+    ,
     .tp_richcompare = map_tp_richcompare,
     .tp_traverse = (traverseproc)map_tp_traverse,
     .tp_clear = (inquiry)map_tp_clear,

tests/conftest.py

@@ -1,3 +1,4 @@
+import sys
 # We need the mypy pytest plugin to do the test collection for our
 # typing tests.
 
@@ -11,3 +12,6 @@
 pytest_plugins = [
     'mypy.test.data',
 ]
+
+if sys.version_info < (3, 10):
+    collect_ignore = ["test_pattern_matching.py"]

tests/test_pattern_matching.py

@@ -0,0 +1,38 @@
+import unittest
+
+from immutables.map import Map as PyMap
+
+
+class BaseMapTest:
+
+    Map = None
+
+    def test_map_can_be_matched(self):
+        match self.Map(a=1, b=2):  # noqa: E999
+            case {"a": 1 as matched}:
+                matched = matched
+            case _:
+                assert False
+
+        assert matched == 1
+
+
+class PyMapTest(BaseMapTest, unittest.TestCase):
+
+    Map = PyMap
+
+
+try:
+    from immutables._map import Map as CMap
+except ImportError:
+    CMap = None
+
+
+@unittest.skipIf(CMap is None, 'C Map is not available')
+class CMapTest(BaseMapTest, unittest.TestCase):
+
+    Map = CMap
+
+
+if __name__ == "__main__":
+    unittest.main()