Make the new dictionary iterators transparent with respect to length.

This gives another 30% speedup for operations such as
map(func, d.iteritems()) or list(d.iteritems()) which can both take
advantage of length information when provided.

diff --git a/Objects/dictobject.c b/Objects/dictobject.c
index 1be0f421502d14bfd8193220b5bc1be03777860e..7afc57600a659f6f5977e074acf7659dbdcdb3ab 100644 (file)
--- a/Objects/dictobject.c
+++ b/Objects/dictobject.c
@@ -2013,6 +2013,7 @@ typedef struct {
        int di_used;
        int di_pos;
        PyObject* di_result; /* reusable result tuple for iteritems */
+       long len;
 } dictiterobject;
 
 static PyObject *
@@ -2026,6 +2027,7 @@ dictiter_new(dictobject *dict, PyTypeObject *itertype)
        di->di_dict = dict;
        di->di_used = dict->ma_used;
        di->di_pos = 0;
+       di->len = dict->ma_used;
        if (itertype == &PyDictIterItem_Type) {
                di->di_result = PyTuple_Pack(2, Py_None, Py_None);
                if (di->di_result == NULL) {
@@ -2046,6 +2048,17 @@ dictiter_dealloc(dictiterobject *di)
        PyObject_Del(di);
 }
 
+static int
+dictiter_len(dictiterobject *di)
+{
+       return di->len;
+}
+
+static PySequenceMethods dictiter_as_sequence = {
+       (inquiry)dictiter_len,          /* sq_length */
+       0,                              /* sq_concat */
+};
+
 static PyObject *dictiter_iternextkey(dictiterobject *di)
 {
        PyObject *key;
@@ -2074,6 +2087,7 @@ static PyObject *dictiter_iternextkey(dictiterobject *di)
        di->di_pos = i+1;
        if (i > mask)
                goto fail;
+       di->len--;
        key = ep[i].me_key;
        Py_INCREF(key);
        return key;
@@ -2087,7 +2101,7 @@ fail:
 PyTypeObject PyDictIterKey_Type = {
        PyObject_HEAD_INIT(&PyType_Type)
        0,                                      /* ob_size */
-       "dictionary-keyiterator",                       /* tp_name */
+       "dictionary-keyiterator",               /* tp_name */
        sizeof(dictiterobject),                 /* tp_basicsize */
        0,                                      /* tp_itemsize */
        /* methods */
@@ -2098,7 +2112,7 @@ PyTypeObject PyDictIterKey_Type = {
        0,                                      /* tp_compare */
        0,                                      /* tp_repr */
        0,                                      /* tp_as_number */
-       0,                                      /* tp_as_sequence */
+       &dictiter_as_sequence,                  /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */
@@ -2144,6 +2158,7 @@ static PyObject *dictiter_iternextvalue(dictiterobject *di)
        di->di_pos = i+1;
        if (i > mask)
                goto fail;
+       di->len--;
        Py_INCREF(value);
        return value;
 
@@ -2167,7 +2182,7 @@ PyTypeObject PyDictIterValue_Type = {
        0,                                      /* tp_compare */
        0,                                      /* tp_repr */
        0,                                      /* tp_as_number */
-       0,                                      /* tp_as_sequence */
+       &dictiter_as_sequence,                  /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */
@@ -2223,6 +2238,7 @@ static PyObject *dictiter_iternextitem(dictiterobject *di)
                if (result == NULL) 
                        return NULL;
        }
+       di->len--;
        key = ep[i].me_key;
        value = ep[i].me_value;
        Py_INCREF(key);
@@ -2251,7 +2267,7 @@ PyTypeObject PyDictIterItem_Type = {
        0,                                      /* tp_compare */
        0,                                      /* tp_repr */
        0,                                      /* tp_as_number */
-       0,                                      /* tp_as_sequence */
+       &dictiter_as_sequence,                  /* tp_as_sequence */
        0,                                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */