bpo-36144: OrderedDict Union (PEP 584) (#18967)

Author: brandtbucher

Doc/library/collections.rst

@@ -1123,6 +1123,10 @@ anywhere a regular dictionary is used.
    passed to the :class:`OrderedDict` constructor and its :meth:`update`
    method.
 
+.. versionchanged:: 3.9
+    Added merge (``|``) and update (``|=``) operators, specified in :pep:`584`.
+
+
 :class:`OrderedDict` Examples and Recipes
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 

Lib/collections/__init__.py

@@ -293,6 +293,24 @@ def __eq__(self, other):
             return dict.__eq__(self, other) and all(map(_eq, self, other))
         return dict.__eq__(self, other)
 
+    def __ior__(self, other):
+        self.update(other)
+        return self
+
+    def __or__(self, other):
+        if not isinstance(other, dict):
+            return NotImplemented
+        new = self.__class__(self)
+        new.update(other)
+        return new
+
+    def __ror__(self, other):
+        if not isinstance(other, dict):
+            return NotImplemented
+        new = self.__class__(other)
+        new.update(self)
+        return new
+
 
 try:
     from _collections import OrderedDict

Lib/test/test_ordered_dict.py

@@ -654,6 +654,49 @@ def test_free_after_iterating(self):
         support.check_free_after_iterating(self, lambda d: iter(d.values()), self.OrderedDict)
         support.check_free_after_iterating(self, lambda d: iter(d.items()), self.OrderedDict)
 
+    def test_merge_operator(self):
+        OrderedDict = self.OrderedDict
+
+        a = OrderedDict({0: 0, 1: 1, 2: 1})
+        b = OrderedDict({1: 1, 2: 2, 3: 3})
+
+        c = a.copy()
+        d = a.copy()
+        c |= b
+        d |= list(b.items())
+        expected = OrderedDict({0: 0, 1: 1, 2: 2, 3: 3})
+        self.assertEqual(a | dict(b), expected)
+        self.assertEqual(a | b, expected)
+        self.assertEqual(c, expected)
+        self.assertEqual(d, expected)
+
+        c = b.copy()
+        c |= a
+        expected = OrderedDict({1: 1, 2: 1, 3: 3, 0: 0})
+        self.assertEqual(dict(b) | a, expected)
+        self.assertEqual(b | a, expected)
+        self.assertEqual(c, expected)
+
+        self.assertIs(type(a | b), OrderedDict)
+        self.assertIs(type(dict(a) | b), OrderedDict)
+        self.assertIs(type(a | dict(b)), OrderedDict)
+
+        expected = a.copy()
+        a |= ()
+        a |= ""
+        self.assertEqual(a, expected)
+
+        with self.assertRaises(TypeError):
+            a | None
+        with self.assertRaises(TypeError):
+            a | ()
+        with self.assertRaises(TypeError):
+            a | "BAD"
+        with self.assertRaises(TypeError):
+            a | ""
+        with self.assertRaises(ValueError):
+            a |= "BAD"
+
 
 class PurePythonOrderedDictTests(OrderedDictTests, unittest.TestCase):
 

Misc/NEWS.d/next/Library/2020-03-12-11-55-16.bpo-36144.9bxGH_.rst

@@ -0,0 +1,2 @@
+:class:`collections.OrderedDict` now implements ``|`` and ``|=``
+(:pep:`584`).

Objects/odictobject.c

@@ -851,6 +851,57 @@ static PyMappingMethods odict_as_mapping = {
 };
 
 
+/* ----------------------------------------------
+ * OrderedDict number methods
+ */
+
+static int mutablemapping_update_arg(PyObject*, PyObject*);
+
+static PyObject *
+odict_or(PyObject *left, PyObject *right)
+{
+    PyTypeObject *type;
+    PyObject *other;
+    if (PyODict_Check(left)) {
+        type = Py_TYPE(left);
+        other = right;
+    }
+    else {
+        type = Py_TYPE(right);
+        other = left;
+    }
+    if (!PyDict_Check(other)) {
+        Py_RETURN_NOTIMPLEMENTED;
+    }
+    PyObject *new = PyObject_CallOneArg((PyObject*)type, left);
+    if (!new) {
+        return NULL;
+    }
+    if (mutablemapping_update_arg(new, right) < 0) {
+        Py_DECREF(new);
+        return NULL;
+    }
+    return new;
+}
+
+static PyObject *
+odict_inplace_or(PyObject *self, PyObject *other)
+{
+    if (mutablemapping_update_arg(self, other) < 0) {
+        return NULL;
+    }
+    Py_INCREF(self); 
+    return self;
+}
+
+/* tp_as_number */
+
+static PyNumberMethods odict_as_number = {
+    .nb_or = odict_or,
+    .nb_inplace_or = odict_inplace_or,
+};
+
+
 /* ----------------------------------------------
  * OrderedDict methods
  */
@@ -1555,7 +1606,7 @@ PyTypeObject PyODict_Type = {
     0,                                          /* tp_setattr */
     0,                                          /* tp_as_async */
     (reprfunc)odict_repr,                       /* tp_repr */
-    0,                                          /* tp_as_number */
+    &odict_as_number,                           /* tp_as_number */
     0,                                          /* tp_as_sequence */
     &odict_as_mapping,                          /* tp_as_mapping */
     0,                                          /* tp_hash */
@@ -2189,100 +2240,94 @@ mutablemapping_add_pairs(PyObject *self, PyObject *pairs)
         return 0;
 }
 
-static PyObject *
-mutablemapping_update(PyObject *self, PyObject *args, PyObject *kwargs)
+static int
+mutablemapping_update_arg(PyObject *self, PyObject *arg)
 {
     int res = 0;
-    Py_ssize_t len;
+    if (PyDict_CheckExact(arg)) {
+        PyObject *items = PyDict_Items(arg);
+        if (items == NULL) {
+            return -1;
+        }
+        res = mutablemapping_add_pairs(self, items);
+        Py_DECREF(items);
+        return res;
+    }
     _Py_IDENTIFIER(keys);
+    PyObject *func;
+    if (_PyObject_LookupAttrId(arg, &PyId_keys, &func) < 0) {
+        return -1;
+    }
+    if (func != NULL) {
+        PyObject *keys = _PyObject_CallNoArg(func);
+        Py_DECREF(func);
+        if (keys == NULL) {
+            return -1;
+        }
+        PyObject *iterator = PyObject_GetIter(keys);
+        Py_DECREF(keys);
+        if (iterator == NULL) {
+            return -1;
+        }
+        PyObject *key;
+        while (res == 0 && (key = PyIter_Next(iterator))) {
+            PyObject *value = PyObject_GetItem(arg, key);
+            if (value != NULL) {
+                res = PyObject_SetItem(self, key, value);
+                Py_DECREF(value);
+            }
+            else {
+                res = -1;
+            }
+            Py_DECREF(key);
+        }
+        Py_DECREF(iterator);
+        if (res != 0 || PyErr_Occurred()) {
+            return -1;
+        }
+        return 0;
+    }
+    if (_PyObject_LookupAttrId(arg, &PyId_items, &func) < 0) {
+        return -1;
+    }
+    if (func != NULL) {
+        PyObject *items = _PyObject_CallNoArg(func);
+        Py_DECREF(func);
+        if (items == NULL) {
+            return -1;
+        }
+        res = mutablemapping_add_pairs(self, items);
+        Py_DECREF(items);
+        return res;
+    }
+    res = mutablemapping_add_pairs(self, arg);
+    return res;
+}
 
+static PyObject *
+mutablemapping_update(PyObject *self, PyObject *args, PyObject *kwargs)
+{
+    int res;
     /* first handle args, if any */
     assert(args == NULL || PyTuple_Check(args));
-    len = (args != NULL) ? PyTuple_GET_SIZE(args) : 0;
+    Py_ssize_t len = (args != NULL) ? PyTuple_GET_SIZE(args) : 0;
     if (len > 1) {
         const char *msg = "update() takes at most 1 positional argument (%zd given)";
         PyErr_Format(PyExc_TypeError, msg, len);
         return NULL;
     }
 
     if (len) {
-        PyObject *func;
         PyObject *other = PyTuple_GET_ITEM(args, 0);  /* borrowed reference */
         assert(other != NULL);
         Py_INCREF(other);
-        if (PyDict_CheckExact(other)) {
-            PyObject *items = PyDict_Items(other);
-            Py_DECREF(other);
-            if (items == NULL)
-                return NULL;
-            res = mutablemapping_add_pairs(self, items);
-            Py_DECREF(items);
-            if (res == -1)
-                return NULL;
-            goto handle_kwargs;
-        }
-
-        if (_PyObject_LookupAttrId(other, &PyId_keys, &func) < 0) {
-            Py_DECREF(other);
-            return NULL;
-        }
-        if (func != NULL) {
-            PyObject *keys, *iterator, *key;
-            keys = _PyObject_CallNoArg(func);
-            Py_DECREF(func);
-            if (keys == NULL) {
-                Py_DECREF(other);
-                return NULL;
-            }
-            iterator = PyObject_GetIter(keys);
-            Py_DECREF(keys);
-            if (iterator == NULL) {
-                Py_DECREF(other);
-                return NULL;
-            }
-            while (res == 0 && (key = PyIter_Next(iterator))) {
-                PyObject *value = PyObject_GetItem(other, key);
-                if (value != NULL) {
-                    res = PyObject_SetItem(self, key, value);
-                    Py_DECREF(value);
-                }
-                else {
-                    res = -1;
-                }
-                Py_DECREF(key);
-            }
-            Py_DECREF(other);
-            Py_DECREF(iterator);
-            if (res != 0 || PyErr_Occurred())
-                return NULL;
-            goto handle_kwargs;
-        }
-
-        if (_PyObject_LookupAttrId(other, &PyId_items, &func) < 0) {
-            Py_DECREF(other);
-            return NULL;
-        }
-        if (func != NULL) {
-            PyObject *items;
-            Py_DECREF(other);
-            items = _PyObject_CallNoArg(func);
-            Py_DECREF(func);
-            if (items == NULL)
-                return NULL;
-            res = mutablemapping_add_pairs(self, items);
-            Py_DECREF(items);
-            if (res == -1)
-                return NULL;
-            goto handle_kwargs;
-        }
-
-        res = mutablemapping_add_pairs(self, other);
+        res = mutablemapping_update_arg(self, other);
         Py_DECREF(other);
-        if (res != 0)
+        if (res < 0) {
             return NULL;
+        }
     }
 
-  handle_kwargs:
     /* now handle kwargs */
     assert(kwargs == NULL || PyDict_Check(kwargs));
     if (kwargs != NULL && PyDict_GET_SIZE(kwargs)) {