Implement dict copy primitive

Author: vsakkas

mypyc/lib-rt/CPy.h

@@ -349,6 +349,7 @@ PyObject *CPyDict_Keys(PyObject *dict);
 PyObject *CPyDict_Values(PyObject *dict);
 PyObject *CPyDict_Items(PyObject *dict);
 char CPyDict_Clear(PyObject *dict);
+PyObject *CPyDict_Copy(PyObject *dict);
 PyObject *CPyDict_GetKeysIter(PyObject *dict);
 PyObject *CPyDict_GetItemsIter(PyObject *dict);
 PyObject *CPyDict_GetValuesIter(PyObject *dict);

mypyc/lib-rt/dict_ops.c

@@ -238,6 +238,13 @@ char CPyDict_Clear(PyObject *dict) {
     return 1;
 }
 
+PyObject *CPyDict_Copy(PyObject *dict) {
+    if (PyDict_CheckExact(dict)) {
+        return PyDict_Copy(dict);
+    }
+    return PyObject_CallMethod(dict, "copy", NULL);
+}
+
 PyObject *CPyDict_GetKeysIter(PyObject *dict) {
     if (PyDict_CheckExact(dict)) {
         // Return dict itself to indicate we can use fast path instead.

mypyc/primitives/dict_ops.py

@@ -150,6 +150,14 @@
     c_function_name='CPyDict_Clear',
     error_kind=ERR_FALSE)
 
+# dict.copy()
+method_op(
+    name='copy',
+    arg_types=[dict_rprimitive],
+    return_type=dict_rprimitive,
+    c_function_name='CPyDict_Copy',
+    error_kind=ERR_MAGIC)
+
 # list(dict.keys())
 dict_keys_op = custom_op(
     arg_types=[dict_rprimitive],

mypyc/test-data/fixtures/ir.py

@@ -173,6 +173,7 @@ def keys(self) -> Iterable[K]: pass
     def values(self) -> Iterable[V]: pass
     def items(self) -> Iterable[Tuple[K, V]]: pass
     def clear(self) -> None: pass
+    def copy(self) -> Dict[K, V]: pass
 
 class set(Generic[T]):
     def __init__(self, i: Optional[Iterable[T]] = None) -> None: pass

mypyc/test-data/irbuild-dict.test

@@ -324,3 +324,14 @@ def f(d):
 L0:
     r0 = CPyDict_Clear(d)
     return 1
+
+[case testDictCopy]
+from typing import Dict
+def f(d: Dict[int, int]) -> Dict[int, int]:
+    return d.copy()
+[out]
+def f(d):
+    d, r0 :: dict
+L0:
+    r0 = CPyDict_Copy(d)
+    return r0

mypyc/test-data/run-dicts.test

@@ -206,3 +206,14 @@ def test_dict_clear() -> None:
     dd['a'] = 1
     dd.clear()
     assert dd == {}
+
+def test_dict_copy() -> None:
+    d: Dict[str, int] = {}
+    assert d.copy() == d
+    d = {'a': 1, 'b': 2}
+    assert d.copy() == d
+    assert d.copy() is not d
+    dd: Dict[str, int] = defaultdict(int)
+    dd['a'] = 1
+    assert dd.copy() == dd
+    assert isinstance(dd.copy(), defaultdict)