Very preliminary work on dict views.

diff --git a/Lib/test/test_dictviews.py b/Lib/test/test_dictviews.py
new file mode 100644 (file)
index 0000000..15c933f
--- /dev/null
+++ b/Lib/test/test_dictviews.py
@@ -0,0 +1,25 @@
+import unittest
+from test import test_support
+
+class DictSetTest(unittest.TestCase):
+
+    def test_dict_keys(self):
+        d = {1: 10, "a": "ABC"}
+        keys = d.KEYS()
+        self.assertEqual(set(keys), {1, "a"})
+
+    def test_dict_items(self):
+        d = {1: 10, "a": "ABC"}
+        items = d.ITEMS()
+        self.assertEqual(set(items), {(1, 10), ("a", "ABC")})
+
+    def test_dict_values(self):
+        d = {1: 10, "a": "ABC"}
+        values = d.VALUES()
+        self.assertEqual(set(values), {10, "ABC"})
+
+def test_main():
+    test_support.run_unittest(DictSetTest)
+
+if __name__ == "__main__":
+    test_main()

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 09aba61c90289a2f29754d3281b019dbb7d7cbef..bb527ddc3f571078f267c63099f6e71854f6a884 100644 (file)
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -1808,8 +1808,8 @@ PyDoc_STRVAR(values__doc__,
 "D.values() -> list of D's values");
 
 PyDoc_STRVAR(update__doc__,
-"D.update(E, **F) -> None.  Update D from E and F: for k in E: D[k] = E[k]\n\
-(if E has keys else: for (k, v) in E: D[k] = v) then: for k in F: D[k] = F[k]");
+"D.update(E, **F) -> None.  Update D from E and F: for k in E: D[k] = E[k]\
+\n(if E has keys else: for (k, v) in E: D[k] = v) then: for k in F: D[k] = F[k]");
 
 PyDoc_STRVAR(fromkeys__doc__,
 "dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v.\n\
@@ -1830,6 +1830,15 @@ PyDoc_STRVAR(itervalues__doc__,
 PyDoc_STRVAR(iteritems__doc__,
 "D.iteritems() -> an iterator over the (key, value) items of D");
 
+/* Forward */
+static PyObject *dictkeys_new(PyObject *);
+static PyObject *dictitems_new(PyObject *);
+static PyObject *dictvalues_new(PyObject *);
+
+PyDoc_STRVAR(KEYS__doc__, "D.KEYS() -> a set-like object for D's keys");
+PyDoc_STRVAR(ITEMS__doc__, "D.ITEMS() -> a set-like object for D's items");
+PyDoc_STRVAR(VALUES__doc__, "D.VALUES() -> a set-like object for D's values");
+
 static PyMethodDef mapp_methods[] = {
        {"__contains__",(PyCFunction)dict_contains,     METH_O | METH_COEXIST,
         contains__doc__},
@@ -1845,6 +1854,12 @@ static PyMethodDef mapp_methods[] = {
         popitem__doc__},
        {"keys",        (PyCFunction)dict_keys,         METH_NOARGS,
        keys__doc__},
+       {"KEYS",        (PyCFunction)dictkeys_new,      METH_NOARGS,
+       KEYS__doc__},
+       {"ITEMS",       (PyCFunction)dictitems_new,     METH_NOARGS,
+       ITEMS__doc__},
+       {"VALUES",      (PyCFunction)dictvalues_new,    METH_NOARGS,
+       VALUES__doc__},
        {"items",       (PyCFunction)dict_items,        METH_NOARGS,
         items__doc__},
        {"values",      (PyCFunction)dict_values,       METH_NOARGS,
@@ -2078,10 +2093,12 @@ dictiter_len(dictiterobject *di)
        return PyInt_FromSize_t(len);
 }
 
-PyDoc_STRVAR(length_hint_doc, "Private method returning an estimate of len(list(it)).");
+PyDoc_STRVAR(length_hint_doc,
+             "Private method returning an estimate of len(list(it)).");
 
 static PyMethodDef dictiter_methods[] = {
-       {"__length_hint__", (PyCFunction)dictiter_len, METH_NOARGS, length_hint_doc},
+       {"__length_hint__", (PyCFunction)dictiter_len, METH_NOARGS,
+         length_hint_doc},
        {NULL,          NULL}           /* sentinel */
 };
 
@@ -2317,3 +2334,225 @@ PyTypeObject PyDictIterItem_Type = {
        dictiter_methods,                       /* tp_methods */
        0,
 };
+
+
+/* View objects for keys(), items(), values(). */
+/* While this is incomplete, we use KEYS(), ITEMS(), VALUES(). */
+
+/* The instance lay-out is the same for all three; but the type differs. */
+
+typedef struct {
+       PyObject_HEAD
+       dictobject *ds_dict;
+} dictviewobject;
+
+
+static void
+dictview_dealloc(dictviewobject *ds)
+{
+       Py_XDECREF(ds->ds_dict);
+       PyObject_Del(ds);
+}
+
+static PyObject *
+dictview_length_hint(dictviewobject *ds)
+{
+       Py_ssize_t len = 0;
+       if (ds->ds_dict != NULL)
+               len = ds->ds_dict->ma_used;
+       return PyInt_FromSize_t(len);
+}
+
+static PyObject *
+dictview_new(PyObject *dict, PyTypeObject *type)
+{
+       dictviewobject *ds;
+       if (dict == NULL) {
+               PyErr_BadInternalCall();
+               return NULL;
+       }
+       if (!PyDict_Check(dict)) {
+               /* XXX Get rid of this restriction later */
+               PyErr_Format(PyExc_TypeError,
+                            "%s() requires a dict argument, not '%s'",
+                            type->tp_name, dict->ob_type->tp_name);
+               return NULL;
+       }
+       ds = PyObject_New(dictviewobject, type);
+       if (ds == NULL)
+               return NULL;
+       Py_INCREF(dict);
+       ds->ds_dict = (dictobject *)dict;
+       return (PyObject *)ds;
+}
+
+/* dict_keys */
+
+static PyObject *
+dictkeys_iter(dictviewobject *ds)
+{
+       if (ds->ds_dict == NULL) {
+               Py_RETURN_NONE;
+       }
+       return dictiter_new(ds->ds_dict, &PyDictIterKey_Type);
+}
+
+static PyMethodDef dictkeys_methods[] = {
+       {"__length_hint__", (PyCFunction)dictview_length_hint, METH_NOARGS,
+         length_hint_doc},
+       {NULL,          NULL}           /* sentinel */
+};
+
+PyTypeObject PyDictKeys_Type = {
+       PyObject_HEAD_INIT(&PyType_Type)
+       0,                                      /* ob_size */
+       "dict_keys",                            /* tp_name */
+       sizeof(dictviewobject),                 /* tp_basicsize */
+       0,                                      /* tp_itemsize */
+       /* methods */
+       (destructor)dictview_dealloc,           /* tp_dealloc */
+       0,                                      /* tp_print */
+       0,                                      /* tp_getattr */
+       0,                                      /* tp_setattr */
+       0,                                      /* tp_compare */
+       0,                                      /* tp_repr */
+       0,                                      /* tp_as_number */
+       0,                                      /* tp_as_sequence */
+       0,                                      /* tp_as_mapping */
+       0,                                      /* tp_hash */
+       0,                                      /* tp_call */
+       0,                                      /* tp_str */
+       PyObject_GenericGetAttr,                /* tp_getattro */
+       0,                                      /* tp_setattro */
+       0,                                      /* tp_as_buffer */
+       Py_TPFLAGS_DEFAULT,                     /* tp_flags */
+       0,                                      /* tp_doc */
+       0,                                      /* tp_traverse */
+       0,                                      /* tp_clear */
+       0,                                      /* tp_richcompare */
+       0,                                      /* tp_weaklistoffset */
+       (getiterfunc)dictkeys_iter,             /* tp_iter */
+       0,                                      /* tp_iternext */
+       dictkeys_methods,                       /* tp_methods */
+       0,
+};
+
+static PyObject *
+dictkeys_new(PyObject *dict)
+{
+       return dictview_new(dict, &PyDictKeys_Type);
+}
+
+/* dict_items */
+
+static PyObject *
+dictitems_iter(dictviewobject *ds)
+{
+       if (ds->ds_dict == NULL) {
+               Py_RETURN_NONE;
+       }
+       return dictiter_new(ds->ds_dict, &PyDictIterItem_Type);
+}
+
+static PyMethodDef dictitems_methods[] = {
+       {"__length_hint__", (PyCFunction)dictview_length_hint, METH_NOARGS,
+         length_hint_doc},
+       {NULL,          NULL}           /* sentinel */
+};
+
+PyTypeObject PyDictItems_Type = {
+       PyObject_HEAD_INIT(&PyType_Type)
+       0,                                      /* ob_size */
+       "dict_items",                           /* tp_name */
+       sizeof(dictviewobject),                 /* tp_basicsize */
+       0,                                      /* tp_itemsize */
+       /* methods */
+       (destructor)dictview_dealloc,           /* tp_dealloc */
+       0,                                      /* tp_print */
+       0,                                      /* tp_getattr */
+       0,                                      /* tp_setattr */
+       0,                                      /* tp_compare */
+       0,                                      /* tp_repr */
+       0,                                      /* tp_as_number */
+       0,                                      /* tp_as_sequence */
+       0,                                      /* tp_as_mapping */
+       0,                                      /* tp_hash */
+       0,                                      /* tp_call */
+       0,                                      /* tp_str */
+       PyObject_GenericGetAttr,                /* tp_getattro */
+       0,                                      /* tp_setattro */
+       0,                                      /* tp_as_buffer */
+       Py_TPFLAGS_DEFAULT,                     /* tp_flags */
+       0,                                      /* tp_doc */
+       0,                                      /* tp_traverse */
+       0,                                      /* tp_clear */
+       0,                                      /* tp_richcompare */
+       0,                                      /* tp_weaklistoffset */
+       (getiterfunc)dictitems_iter,            /* tp_iter */
+       0,                                      /* tp_iternext */
+       dictitems_methods,                      /* tp_methods */
+       0,
+};
+
+static PyObject *
+dictitems_new(PyObject *dict)
+{
+       return dictview_new(dict, &PyDictItems_Type);
+}
+
+/* dict_values */
+
+static PyObject *
+dictvalues_iter(dictviewobject *ds)
+{
+       if (ds->ds_dict == NULL) {
+               Py_RETURN_NONE;
+       }
+       return dictiter_new(ds->ds_dict, &PyDictIterValue_Type);
+}
+
+static PyMethodDef dictvalues_methods[] = {
+       {"__length_hint__", (PyCFunction)dictview_length_hint, METH_NOARGS,
+         length_hint_doc},
+       {NULL,          NULL}           /* sentinel */
+};
+
+PyTypeObject PyDictValues_Type = {
+       PyObject_HEAD_INIT(&PyType_Type)
+       0,                                      /* ob_size */
+       "dict_values",                          /* tp_name */
+       sizeof(dictviewobject),                 /* tp_basicsize */
+       0,                                      /* tp_itemsize */
+       /* methods */
+       (destructor)dictview_dealloc,           /* tp_dealloc */
+       0,                                      /* tp_print */
+       0,                                      /* tp_getattr */
+       0,                                      /* tp_setattr */
+       0,                                      /* tp_compare */
+       0,                                      /* tp_repr */
+       0,                                      /* tp_as_number */
+       0,                                      /* tp_as_sequence */
+       0,                                      /* tp_as_mapping */
+       0,                                      /* tp_hash */
+       0,                                      /* tp_call */
+       0,                                      /* tp_str */
+       PyObject_GenericGetAttr,                /* tp_getattro */
+       0,                                      /* tp_setattro */
+       0,                                      /* tp_as_buffer */
+       Py_TPFLAGS_DEFAULT,                     /* tp_flags */
+       0,                                      /* tp_doc */
+       0,                                      /* tp_traverse */
+       0,                                      /* tp_clear */
+       0,                                      /* tp_richcompare */
+       0,                                      /* tp_weaklistoffset */
+       (getiterfunc)dictvalues_iter,           /* tp_iter */
+       0,                                      /* tp_iternext */
+       dictvalues_methods,                     /* tp_methods */
+       0,
+};
+
+static PyObject *
+dictvalues_new(PyObject *dict)
+{
+       return dictview_new(dict, &PyDictValues_Type);
+}