Eeked out another 3% or so performance in split whitespace by cleaning up the algorithm.

diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 70a2e7710a0c5103e138026f4c9415b3c13e6844..3f1e482857b2a7c073975eafb9a97f5c3b2d1ca3 100644 (file)
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -1460,7 +1460,7 @@ static const char *stripformat[] = {"|O:lstrip", "|O:rstrip", "|O:strip"};
        else                                                    \
                Py_DECREF(str);
 
-#define SPLIT_ADD(data, left, right)                           \
+#define SPLIT_ADD(data, left, right) {                         \
        str = PyString_FromStringAndSize((data) + (left),       \
                                         (right) - (left));     \
        if (str == NULL)                                        \
@@ -1475,11 +1475,16 @@ static const char *stripformat[] = {"|O:lstrip", "|O:rstrip", "|O:strip"};
                else                                            \
                        Py_DECREF(str);                         \
        }                                                       \
-       count++;
+       count++; }
 
 /* Always force the list to the expected size. */
 #define FIX_PREALLOC_SIZE(list) ((PyListObject *)list)->ob_size = count;               
 
+#define SKIP_SPACE(s, i, len)    { while (i<len &&  isspace(Py_CHARMASK(s[i]))) i++; }
+#define SKIP_NONSPACE(s, i, len) { while (i<len && !isspace(Py_CHARMASK(s[i]))) i++; }
+#define RSKIP_SPACE(s, i)        { while (i>=0  &&  isspace(Py_CHARMASK(s[i]))) i--; }
+#define RSKIP_NONSPACE(s, i)     { while (i>=0  && !isspace(Py_CHARMASK(s[i]))) i--; }
+
 static PyObject *
 split_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
 {
@@ -1490,23 +1495,22 @@ split_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
        if (list == NULL)
                return NULL;
 
-       for (i = j = 0; i < len; ) {
-               while (i < len && isspace(Py_CHARMASK(s[i])))
-                       i++;
-               j = i;
-               while (i < len && !isspace(Py_CHARMASK(s[i])))
-                       i++;
-               if (j < i) {
-                       if (maxsplit-- <= 0)
-                               break;
-                       SPLIT_ADD(s, j, i);
-                       while (i < len && isspace(Py_CHARMASK(s[i])))
-                               i++;
-                       j = i;
-               }
+       i = j = 0;
+
+       while (maxsplit-- > 0) {
+               SKIP_SPACE(s, i, len);
+               if (i==len) break;
+               j = i; i++;
+               SKIP_NONSPACE(s, i, len);
+               SPLIT_ADD(s, j, i);
        }
-       if (j < len) {
-               SPLIT_ADD(s, j, len);
+
+       if (i < len) {
+               /* Only occurs when maxsplit was reached */
+               /* Skip any remaining whitespace and copy to end of string */
+               SKIP_SPACE(s, i, len);
+               if (i != len)
+                       SPLIT_ADD(s, i, len);
        }
        FIX_PREALLOC_SIZE(list);
        return list;
@@ -1680,23 +1684,22 @@ rsplit_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
        if (list == NULL)
                return NULL;
 
-       for (i = j = len - 1; i >= 0; ) {
-               while (i >= 0 && isspace(Py_CHARMASK(s[i])))
-                       i--;
-               j = i;
-               while (i >= 0 && !isspace(Py_CHARMASK(s[i])))
-                       i--;
-               if (j > i) {
-                       if (maxsplit-- <= 0)
-                               break;
-                       SPLIT_ADD(s, i + 1, j + 1);
-                       while (i >= 0 && isspace(Py_CHARMASK(s[i])))
-                               i--;
-                       j = i;
-               }
-       }
-       if (j >= 0) {
-               SPLIT_ADD(s, 0, j + 1);
+       i = j = len-1;
+       
+       while (maxsplit-- > 0) {
+               RSKIP_SPACE(s, i);
+               if (i<0) break;
+               j = i; i--;
+               RSKIP_NONSPACE(s, i);
+               SPLIT_ADD(s, i + 1, j + 1);
+       }
+       if (i >= 0) {
+               /* Only occurs when maxsplit was reached */
+               /* Skip any remaining whitespace and copy to beginning of string */
+               RSKIP_SPACE(s, i);
+               if (i >= 0)
+                       SPLIT_ADD(s, 0, i + 1);
+
        }
        FIX_PREALLOC_SIZE(list);
        if (PyList_Reverse(list) < 0)