Add PyDict_Merge(a, b, override):
PyDict_Merge(a, b, 1) is the same as PyDict_Update(a, b).
PyDict_Merge(a, b, 0) does something similar but leaves existing items
unchanged.
diff --git a/Include/dictobject.h b/Include/dictobject.h
index abc8ed5..1132021 100644
--- a/Include/dictobject.h
+++ b/Include/dictobject.h
@@ -98,6 +98,7 @@
extern DL_IMPORT(int) PyDict_Size(PyObject *mp);
extern DL_IMPORT(PyObject *) PyDict_Copy(PyObject *mp);
extern DL_IMPORT(int) PyDict_Update(PyObject *mp, PyObject *other);
+extern DL_IMPORT(int) PyDict_Merge(PyObject *mp, PyObject *other, int override);
extern DL_IMPORT(PyObject *) PyDict_GetItemString(PyObject *dp, char *key);
diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index ce4c578..73c459f 100644
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -999,9 +999,19 @@
return Py_None;
}
+/* Update unconditionally replaces existing items.
+ Merge has a 3rd argument 'override'; if set, it acts like Update,
+ otherwise it leaves existing items unchanged. */
+
int
PyDict_Update(PyObject *a, PyObject *b)
{
+ return PyDict_Merge(a, b, 1);
+}
+
+int
+PyDict_Merge(PyObject *a, PyObject *b, int override)
+{
register PyDictObject *mp, *other;
register int i;
dictentry *entry;
@@ -1031,7 +1041,9 @@
}
for (i = 0; i <= other->ma_mask; i++) {
entry = &other->ma_table[i];
- if (entry->me_value != NULL) {
+ if (entry->me_value != NULL &&
+ (override ||
+ PyDict_GetItem(a, entry->me_key) == NULL)) {
Py_INCREF(entry->me_key);
Py_INCREF(entry->me_value);
insertdict(mp, entry->me_key, entry->me_hash,
@@ -1060,13 +1072,17 @@
return -1;
for (key = PyIter_Next(iter); key; key = PyIter_Next(iter)) {
+ if (!override && PyDict_GetItem(a, key) != NULL) {
+ Py_DECREF(key);
+ continue;
+ }
value = PyObject_GetItem(b, key);
if (value == NULL) {
Py_DECREF(iter);
Py_DECREF(key);
return -1;
}
- status = PyDict_SetItem((PyObject*)mp, key, value);
+ status = PyDict_SetItem(a, key, value);
Py_DECREF(key);
Py_DECREF(value);
if (status < 0) {