[Python-checkins] cpython: More logicial order. Move space saving step to just before it is used.

[raymond.hettinger]

https://hg.python.org/cpython/rev/c1c8d2e27267
changeset:   100413:c1c8d2e27267
user:        Raymond Hettinger <python at rcn.com>
date:        Fri Mar 04 09:55:07 2016 -0800
summary:
  More logicial order.  Move space saving step to just before it is used.

files:
  Modules/_collectionsmodule.c |  28 ++++++++++++------------
  1 files changed, 14 insertions(+), 14 deletions(-)


diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -386,6 +386,13 @@
         return result;
     }
 
+    it = PyObject_GetIter(iterable);
+    if (it == NULL)
+        return NULL;
+
+    if (maxlen == 0)
+        return consume_iterator(it);
+
     /* Space saving heuristic.  Start filling from the left */
     if (Py_SIZE(deque) == 0) {
         assert(deque->leftblock == deque->rightblock);
@@ -394,13 +401,6 @@
         deque->rightindex = 0;
     }
 
-    it = PyObject_GetIter(iterable);
-    if (it == NULL)
-        return NULL;
-
-    if (maxlen == 0)
-        return consume_iterator(it);
-
     iternext = *Py_TYPE(it)->tp_iternext;
     while ((item = iternext(it)) != NULL) {
         if (deque_append_internal(deque, item, maxlen) < 0) {
@@ -433,6 +433,13 @@
         return result;
     }
 
+    it = PyObject_GetIter(iterable);
+    if (it == NULL)
+        return NULL;
+
+    if (maxlen == 0)
+        return consume_iterator(it);
+
     /* Space saving heuristic.  Start filling from the right */
     if (Py_SIZE(deque) == 0) {
         assert(deque->leftblock == deque->rightblock);
@@ -441,13 +448,6 @@
         deque->rightindex = BLOCKLEN - 2;
     }
 
-    it = PyObject_GetIter(iterable);
-    if (it == NULL)
-        return NULL;
-
-    if (maxlen == 0)
-        return consume_iterator(it);
-
     iternext = *Py_TYPE(it)->tp_iternext;
     while ((item = iternext(it)) != NULL) {
         if (deque_appendleft_internal(deque, item, maxlen) < 0) {

-- 
Repository URL: https://hg.python.org/cpython