Issue #7622: Improve the split(), rsplit(), splitlines() and replace()

methods of bytes, bytearray and unicode objects by using a common
implementation based on stringlib's fast search.  Patch by Florent Xicluna.

17 files changed, 717 insertions, 1442 deletions

diff --git a/Makefile.pre.in b/Makefile.pre.in
index 1491a9b..300a034 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -563,6 +563,7 @@ STRINGLIB_HEADERS= \
 		$(srcdir)/Objects/stringlib/find.h \
 		$(srcdir)/Objects/stringlib/formatter.h \
 		$(srcdir)/Objects/stringlib/partition.h \
+		$(srcdir)/Objects/stringlib/split.h \
 		$(srcdir)/Objects/stringlib/stringdefs.h \
 		$(srcdir)/Objects/stringlib/string_format.h \
 		$(srcdir)/Objects/stringlib/transmogrify.h \
diff --git a/Misc/NEWS b/Misc/NEWS
index d2b75b1..20cdf88 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -12,6 +12,10 @@ What's New in Python 2.7 alpha 3?
 Core and Builtins
 -----------------
 
+- Issue #7622: Improve the split(), rsplit(), splitlines() and replace()
+  methods of bytes, bytearray and unicode objects by using a common
+  implementation based on stringlib's fast search.  Patch by Florent Xicluna.
+
 - Issue #7632: Fix a crash in dtoa.c that occurred in debug builds
   when parsing certain long numeric strings corresponding to subnormal
   values.  Also fix a number of bugs in dtoa.c that could lead to
diff --git a/Objects/bytearrayobject.c b/Objects/bytearrayobject.c
index 6157c83..74cb1f1 100644
--- a/Objects/bytearrayobject.c
+++ b/Objects/bytearrayobject.c
@@ -1115,14 +1115,16 @@ bytearray_dealloc(PyByteArrayObject *self)
 #define STRINGLIB_STR PyByteArray_AS_STRING
 #define STRINGLIB_NEW PyByteArray_FromStringAndSize
 #define STRINGLIB_EMPTY nullbytes
+#define STRINGLIB_ISSPACE Py_ISSPACE
+#define STRINGLIB_ISLINEBREAK(x) ((x == '\n') || (x == '\r'))
 #define STRINGLIB_CHECK_EXACT PyByteArray_CheckExact
 #define STRINGLIB_MUTABLE 1
-#define FROM_BYTEARRAY 1
 
 #include "stringlib/fastsearch.h"
 #include "stringlib/count.h"
 #include "stringlib/find.h"
 #include "stringlib/partition.h"
+#include "stringlib/split.h"
 #include "stringlib/ctype.h"
 #include "stringlib/transmogrify.h"
 
@@ -1130,21 +1132,20 @@ bytearray_dealloc(PyByteArrayObject *self)
 /* The following Py_LOCAL_INLINE and Py_LOCAL functions
 were copied from the old char* style string object. */
 
-Py_LOCAL_INLINE(void)
-_adjust_indices(Py_ssize_t *start, Py_ssize_t *end, Py_ssize_t len)
-{
-    if (*end > len)
-        *end = len;
-    else if (*end < 0)
-        *end += len;
-    if (*end < 0)
-        *end = 0;
-    if (*start < 0)
-        *start += len;
-    if (*start < 0)
-        *start = 0;
-}
-
+/* helper macro to fixup start/end slice values */
+#define ADJUST_INDICES(start, end, len)         \
+    if (end > len)                              \
+        end = len;                              \
+    else if (end < 0) {                         \
+        end += len;                             \
+        if (end < 0)                            \
+            end = 0;                            \
+    }                                           \
+    if (start < 0) {                            \
+        start += len;                           \
+        if (start < 0)                          \
+            start = 0;                          \
+    }
 
 Py_LOCAL_INLINE(Py_ssize_t)
 bytearray_find_internal(PyByteArrayObject *self, PyObject *args, int dir)
@@ -1212,10 +1213,10 @@ bytearray_count(PyByteArrayObject *self, PyObject *args)
     if (_getbuffer(sub_obj, &vsub) < 0)
         return NULL;
 
-    _adjust_indices(&start, &end, PyByteArray_GET_SIZE(self));
+    ADJUST_INDICES(start, end, PyByteArray_GET_SIZE(self));
 
     count_obj = PyInt_FromSsize_t(
-        stringlib_count(str + start, end - start, vsub.buf, vsub.len)
+        stringlib_count(str + start, end - start, vsub.buf, vsub.len, PY_SSIZE_T_MAX)
         );
     PyBuffer_Release(&vsub);
     return count_obj;
@@ -1323,7 +1324,7 @@ _bytearray_tailmatch(PyByteArrayObject *self, PyObject *substr, Py_ssize_t start
     if (_getbuffer(substr, &vsubstr) < 0)
         return -1;
 
-    _adjust_indices(&start, &end, len);
+    ADJUST_INDICES(start, end, len);
 
     if (direction < 0) {
         /* startswith */
@@ -1528,20 +1529,11 @@ done:
 }
 
 
-#define FORWARD 1
-#define REVERSE -1
-
 /* find and count characters and substrings */
 
 #define findchar(target, target_len, c)                         \
   ((char *)memchr((const void *)(target), c, target_len))
 
-/* Don't call if length < 2 */
-#define Py_STRING_MATCH(target, offset, pattern, length)        \
-  (target[offset] == pattern[0] &&                              \
-   target[offset+length-1] == pattern[length-1] &&              \
-   !memcmp(target+offset+1, pattern+1, length-2) )
-
 
 /* Bytes ops must return a string, create a copy */
 Py_LOCAL(PyByteArrayObject *)
@@ -1568,93 +1560,6 @@ countchar(const char *target, Py_ssize_t target_len, char c, Py_ssize_t maxcount
     return count;
 }
 
-Py_LOCAL(Py_ssize_t)
-findstring(const char *target, Py_ssize_t target_len,
-           const char *pattern, Py_ssize_t pattern_len,
-           Py_ssize_t start,
-           Py_ssize_t end,
-           int direction)
-{
-    if (start < 0) {
-        start += target_len;
-        if (start < 0)
-            start = 0;
-    }
-    if (end > target_len) {
-        end = target_len;
-    } else if (end < 0) {
-        end += target_len;
-        if (end < 0)
-            end = 0;
-    }
-
-    /* zero-length substrings always match at the first attempt */
-    if (pattern_len == 0)
-        return (direction > 0) ? start : end;
-
-    end -= pattern_len;
-
-    if (direction < 0) {
-        for (; end >= start; end--)
-            if (Py_STRING_MATCH(target, end, pattern, pattern_len))
-                return end;
-    } else {
-        for (; start <= end; start++)
-            if (Py_STRING_MATCH(target, start, pattern, pattern_len))
-                return start;
-    }
-    return -1;
-}
-
-Py_LOCAL_INLINE(Py_ssize_t)
-countstring(const char *target, Py_ssize_t target_len,
-            const char *pattern, Py_ssize_t pattern_len,
-            Py_ssize_t start,
-            Py_ssize_t end,
-            int direction, Py_ssize_t maxcount)
-{
-    Py_ssize_t count=0;
-
-    if (start < 0) {
-        start += target_len;
-        if (start < 0)
-            start = 0;
-    }
-    if (end > target_len) {
-        end = target_len;
-    } else if (end < 0) {
-        end += target_len;
-        if (end < 0)
-            end = 0;
-    }
-
-    /* zero-length substrings match everywhere */
-    if (pattern_len == 0 || maxcount == 0) {
-        if (target_len+1 < maxcount)
-            return target_len+1;
-        return maxcount;
-    }
-
-    end -= pattern_len;
-    if (direction < 0) {
-        for (; (end >= start); end--)
-            if (Py_STRING_MATCH(target, end, pattern, pattern_len)) {
-                count++;
-                if (--maxcount <= 0) break;
-                end -= pattern_len-1;
-            }
-    } else {
-        for (; (start <= end); start++)
-            if (Py_STRING_MATCH(target, start, pattern, pattern_len)) {
-                count++;
-                if (--maxcount <= 0)
-                    break;
-                start += pattern_len-1;
-            }
-    }
-    return count;
-}
-
 
 /* Algorithms for different cases of string replacement */
 
@@ -1776,10 +1681,9 @@ replace_delete_substring(PyByteArrayObject *self,
     self_len = PyByteArray_GET_SIZE(self);
     self_s = PyByteArray_AS_STRING(self);
 
-    count = countstring(self_s, self_len,
-                        from_s, from_len,
-                        0, self_len, 1,
-                        maxcount);
+    count = stringlib_count(self_s, self_len,
+                            from_s, from_len,
+                            maxcount);
 
     if (count == 0) {
         /* no matches */
@@ -1798,9 +1702,9 @@ replace_delete_substring(PyByteArrayObject *self,
     start = self_s;
     end = self_s + self_len;
     while (count-- > 0) {
-        offset = findstring(start, end-start,
-                            from_s, from_len,
-                            0, end-start, FORWARD);
+        offset = stringlib_find(start, end-start,
+                                from_s, from_len,
+                                0);
         if (offset == -1)
             break;
         next = start + offset;
@@ -1876,9 +1780,9 @@ replace_substring_in_place(PyByteArrayObject *self,
     self_s = PyByteArray_AS_STRING(self);
     self_len = PyByteArray_GET_SIZE(self);
 
-    offset = findstring(self_s, self_len,
-                        from_s, from_len,
-                        0, self_len, FORWARD);
+    offset = stringlib_find(self_s, self_len,
+                            from_s, from_len,
+                            0);
     if (offset == -1) {
         /* No matches; return the original bytes */
         return return_self(self);
@@ -1898,9 +1802,9 @@ replace_substring_in_place(PyByteArrayObject *self,
     end = result_s + self_len;
 
     while ( --maxcount > 0) {
-        offset = findstring(start, end-start,
-                            from_s, from_len,
-                            0, end-start, FORWARD);
+        offset = stringlib_find(start, end-start,
+                                from_s, from_len,
+                                0);
         if (offset==-1)
             break;
         Py_MEMCPY(start+offset, to_s, from_len);
@@ -1993,9 +1897,10 @@ replace_substring(PyByteArrayObject *self,
     self_s = PyByteArray_AS_STRING(self);
     self_len = PyByteArray_GET_SIZE(self);
 
-    count = countstring(self_s, self_len,
-                        from_s, from_len,
-                        0, self_len, FORWARD, maxcount);
+    count = stringlib_count(self_s, self_len,
+                            from_s, from_len,
+                            maxcount);
+
     if (count == 0) {
         /* no matches, return unchanged */
         return return_self(self);
@@ -2022,9 +1927,9 @@ replace_substring(PyByteArrayObject *self,
     start = self_s;
     end = self_s + self_len;
     while (count-- > 0) {
-        offset = findstring(start, end-start,
-                            from_s, from_len,
-                            0, end-start, FORWARD);
+        offset = stringlib_find(start, end-start,
+                                from_s, from_len,
+                                0);
         if (offset == -1)
             break;
         next = start+offset;
@@ -2153,123 +2058,6 @@ bytearray_replace(PyByteArrayObject *self, PyObject *args)
     return res;
 }
 
-
-/* Overallocate the initial list to reduce the number of reallocs for small
-   split sizes.  Eg, "A A A A A A A A A A".split() (10 elements) has three
-   resizes, to sizes 4, 8, then 16.  Most observed string splits are for human
-   text (roughly 11 words per line) and field delimited data (usually 1-10
-   fields).  For large strings the split algorithms are bandwidth limited
-   so increasing the preallocation likely will not improve things.*/
-
-#define MAX_PREALLOC 12
-
-/* 5 splits gives 6 elements */
-#define PREALLOC_SIZE(maxsplit) \
-    (maxsplit >= MAX_PREALLOC ? MAX_PREALLOC : maxsplit+1)
-
-#define SPLIT_APPEND(data, left, right)                         \
-    str = PyByteArray_FromStringAndSize((data) + (left),       \
-                                     (right) - (left));     \
-    if (str == NULL)                                        \
-        goto onError;                                   \
-    if (PyList_Append(list, str)) {                         \
-        Py_DECREF(str);                                 \
-        goto onError;                                   \
-    }                                                       \
-    else                                                    \
-        Py_DECREF(str);
-
-#define SPLIT_ADD(data, left, right) {                          \
-    str = PyByteArray_FromStringAndSize((data) + (left),       \
-                                     (right) - (left));     \
-    if (str == NULL)                                        \
-        goto onError;                                   \
-    if (count < MAX_PREALLOC) {                             \
-        PyList_SET_ITEM(list, count, str);              \
-    } else {                                                \
-        if (PyList_Append(list, str)) {                 \
-            Py_DECREF(str);                         \
-            goto onError;                           \
-        }                                               \
-        else                                            \
-            Py_DECREF(str);                         \
-    }                                                       \
-    count++; }
-
-/* Always force the list to the expected size. */
-#define FIX_PREALLOC_SIZE(list) Py_SIZE(list) = count
-
-
-Py_LOCAL_INLINE(PyObject *)
-split_char(const char *s, Py_ssize_t len, char ch, Py_ssize_t maxcount)
-{
-    register Py_ssize_t i, j, count = 0;
-    PyObject *str;
-    PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
-
-    if (list == NULL)
-        return NULL;
-
-    i = j = 0;
-    while ((j < len) && (maxcount-- > 0)) {
-        for(; j < len; j++) {
-            /* I found that using memchr makes no difference */
-            if (s[j] == ch) {
-                SPLIT_ADD(s, i, j);
-                i = j = j + 1;
-                break;
-            }
-        }
-    }
-    if (i <= len) {
-        SPLIT_ADD(s, i, len);
-    }
-    FIX_PREALLOC_SIZE(list);
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
-}
-
-
-Py_LOCAL_INLINE(PyObject *)
-split_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxcount)
-{
-    register Py_ssize_t i, j, count = 0;
-    PyObject *str;
-    PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
-
-    if (list == NULL)
-        return NULL;
-
-    for (i = j = 0; i < len; ) {
-        /* find a token */
-        while (i < len && Py_ISSPACE(s[i]))
-            i++;
-        j = i;
-        while (i < len && !Py_ISSPACE(s[i]))
-            i++;
-        if (j < i) {
-            if (maxcount-- <= 0)
-                break;
-            SPLIT_ADD(s, j, i);
-            while (i < len && Py_ISSPACE(s[i]))
-                i++;
-            j = i;
-        }
-    }
-    if (j < len) {
-        SPLIT_ADD(s, j, len);
-    }
-    FIX_PREALLOC_SIZE(list);
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
-}
-
 PyDoc_STRVAR(split__doc__,
 "B.split([sep[, maxsplit]]) -> list of bytearray\n\
 \n\
@@ -2281,10 +2069,10 @@ If maxsplit is given, at most maxsplit splits are done.");
 static PyObject *
 bytearray_split(PyByteArrayObject *self, PyObject *args)
 {
-    Py_ssize_t len = PyByteArray_GET_SIZE(self), n, i, j, pos;
-    Py_ssize_t maxsplit = -1, count = 0;
+    Py_ssize_t len = PyByteArray_GET_SIZE(self), n;
+    Py_ssize_t maxsplit = -1;
     const char *s = PyByteArray_AS_STRING(self), *sub;
-    PyObject *list, *str, *subobj = Py_None;
+    PyObject *list, *subobj = Py_None;
     Py_buffer vsub;
 
     if (!PyArg_ParseTuple(args, "|On:split", &subobj, &maxsplit))
@@ -2293,73 +2081,18 @@ bytearray_split(PyByteArrayObject *self, PyObject *args)
         maxsplit = PY_SSIZE_T_MAX;
 
     if (subobj == Py_None)
-        return split_whitespace(s, len, maxsplit);
+        return stringlib_split_whitespace((PyObject*) self, s, len, maxsplit);
 
     if (_getbuffer(subobj, &vsub) < 0)
         return NULL;
     sub = vsub.buf;
     n = vsub.len;
 
-    if (n == 0) {
-        PyErr_SetString(PyExc_ValueError, "empty separator");
-        PyBuffer_Release(&vsub);
-        return NULL;
-    }
-    if (n == 1) {
-        list = split_char(s, len, sub[0], maxsplit);
-        PyBuffer_Release(&vsub);
-        return list;
-    }
-
-    list = PyList_New(PREALLOC_SIZE(maxsplit));
-    if (list == NULL) {
-        PyBuffer_Release(&vsub);
-        return NULL;
-    }
-
-    i = j = 0;
-    while (maxsplit-- > 0) {
-        pos = fastsearch(s+i, len-i, sub, n, FAST_SEARCH);
-        if (pos < 0)
-                break;
-        j = i+pos;
-        SPLIT_ADD(s, i, j);
-        i = j + n;
-    }
-    SPLIT_ADD(s, i, len);
-    FIX_PREALLOC_SIZE(list);
+    list = stringlib_split(
+        (PyObject*) self, s, len, sub, n, maxsplit
+        );
     PyBuffer_Release(&vsub);
     return list;
-
-  onError:
-    Py_DECREF(list);
-    PyBuffer_Release(&vsub);
-    return NULL;
-}
-
-/* stringlib's partition shares nullbytes in some cases.
-   undo this, we don't want the nullbytes to be shared. */
-static PyObject *
-make_nullbytes_unique(PyObject *result)
-{
-    if (result != NULL) {
-        int i;
-        assert(PyTuple_Check(result));
-        assert(PyTuple_GET_SIZE(result) == 3);
-        for (i = 0; i < 3; i++) {
-            if (PyTuple_GET_ITEM(result, i) == (PyObject *)nullbytes) {
-                PyObject *new = PyByteArray_FromStringAndSize(NULL, 0);
-                if (new == NULL) {
-                    Py_DECREF(result);
-                    result = NULL;
-                    break;
-                }
-                Py_DECREF(nullbytes);
-                PyTuple_SET_ITEM(result, i, new);
-            }
-        }
-    }
-    return result;
 }
 
 PyDoc_STRVAR(partition__doc__,
@@ -2386,7 +2119,7 @@ bytearray_partition(PyByteArrayObject *self, PyObject *sep_obj)
             );
 
     Py_DECREF(bytesep);
-    return make_nullbytes_unique(result);
+    return result;
 }
 
 PyDoc_STRVAR(rpartition__doc__,
@@ -2414,81 +2147,7 @@ bytearray_rpartition(PyByteArrayObject *self, PyObject *sep_obj)
             );
 
     Py_DECREF(bytesep);
-    return make_nullbytes_unique(result);
-}
-
-Py_LOCAL_INLINE(PyObject *)
-rsplit_char(const char *s, Py_ssize_t len, char ch, Py_ssize_t maxcount)
-{
-    register Py_ssize_t i, j, count=0;
-    PyObject *str;
-    PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
-
-    if (list == NULL)
-        return NULL;
-
-    i = j = len - 1;
-    while ((i >= 0) && (maxcount-- > 0)) {
-        for (; i >= 0; i--) {
-            if (s[i] == ch) {
-                SPLIT_ADD(s, i + 1, j + 1);
-                j = i = i - 1;
-                break;
-            }
-        }
-    }
-    if (j >= -1) {
-        SPLIT_ADD(s, 0, j + 1);
-    }
-    FIX_PREALLOC_SIZE(list);
-    if (PyList_Reverse(list) < 0)
-        goto onError;
-
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
-}
-
-Py_LOCAL_INLINE(PyObject *)
-rsplit_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxcount)
-{
-    register Py_ssize_t i, j, count = 0;
-    PyObject *str;
-    PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
-
-    if (list == NULL)
-        return NULL;
-
-    for (i = j = len - 1; i >= 0; ) {
-        /* find a token */
-        while (i >= 0 && Py_ISSPACE(s[i]))
-            i--;
-        j = i;
-        while (i >= 0 && !Py_ISSPACE(s[i]))
-            i--;
-        if (j > i) {
-            if (maxcount-- <= 0)
-                break;
-            SPLIT_ADD(s, i + 1, j + 1);
-            while (i >= 0 && Py_ISSPACE(s[i]))
-                i--;
-            j = i;
-        }
-    }
-    if (j >= 0) {
-        SPLIT_ADD(s, 0, j + 1);
-    }
-    FIX_PREALLOC_SIZE(list);
-    if (PyList_Reverse(list) < 0)
-        goto onError;
-
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
+    return result;
 }
 
 PyDoc_STRVAR(rsplit__doc__,
@@ -2503,10 +2162,10 @@ If maxsplit is given, at most maxsplit splits are done.");
 static PyObject *
 bytearray_rsplit(PyByteArrayObject *self, PyObject *args)
 {
-    Py_ssize_t len = PyByteArray_GET_SIZE(self), n, j, pos;
-    Py_ssize_t maxsplit = -1, count = 0;
+    Py_ssize_t len = PyByteArray_GET_SIZE(self), n;
+    Py_ssize_t maxsplit = -1;
     const char *s = PyByteArray_AS_STRING(self), *sub;
-    PyObject *list, *str, *subobj = Py_None;
+    PyObject *list, *subobj = Py_None;
     Py_buffer vsub;
 
     if (!PyArg_ParseTuple(args, "|On:rsplit", &subobj, &maxsplit))
@@ -2515,50 +2174,18 @@ bytearray_rsplit(PyByteArrayObject *self, PyObject *args)
         maxsplit = PY_SSIZE_T_MAX;
 
     if (subobj == Py_None)
-        return rsplit_whitespace(s, len, maxsplit);
+        return stringlib_rsplit_whitespace((PyObject*) self, s, len, maxsplit);
 
     if (_getbuffer(subobj, &vsub) < 0)
         return NULL;
     sub = vsub.buf;
     n = vsub.len;
 
-    if (n == 0) {
-        PyErr_SetString(PyExc_ValueError, "empty separator");
-        PyBuffer_Release(&vsub);
-        return NULL;
-    }
-    else if (n == 1) {
-        list = rsplit_char(s, len, sub[0], maxsplit);
-        PyBuffer_Release(&vsub);
-        return list;
-    }
-
-    list = PyList_New(PREALLOC_SIZE(maxsplit));
-    if (list == NULL) {
-        PyBuffer_Release(&vsub);
-        return NULL;
-    }
-
-    j = len;
-
-    while (maxsplit-- > 0) {
-       pos = fastsearch(s, j, sub, n, FAST_RSEARCH);
-       if (pos < 0)
-           break;
-       SPLIT_ADD(s, pos + n, j);
-       j = pos;
-    }
-    SPLIT_ADD(s, 0, j);
-    FIX_PREALLOC_SIZE(list);
-    if (PyList_Reverse(list) < 0)
-        goto onError;
+    list = stringlib_rsplit(
+        (PyObject*) self, s, len, sub, n, maxsplit
+        );
     PyBuffer_Release(&vsub);
     return list;
-
-onError:
-    Py_DECREF(list);
-    PyBuffer_Release(&vsub);
-    return NULL;
 }
 
 PyDoc_STRVAR(reverse__doc__,
@@ -3026,6 +2653,27 @@ bytearray_join(PyByteArrayObject *self, PyObject *it)
     return NULL;
 }
 
+PyDoc_STRVAR(splitlines__doc__,
+"B.splitlines([keepends]) -> list of lines\n\
+\n\
+Return a list of the lines in B, breaking at line boundaries.\n\
+Line breaks are not included in the resulting list unless keepends\n\
+is given and true.");
+
+static PyObject*
+bytearray_splitlines(PyObject *self, PyObject *args)
+{
+    int keepends = 0;
+
+    if (!PyArg_ParseTuple(args, "|i:splitlines", &keepends))
+        return NULL;
+
+    return stringlib_splitlines(
+        (PyObject*) self, PyByteArray_AS_STRING(self),
+        PyByteArray_GET_SIZE(self), keepends
+        );
+}
+
 PyDoc_STRVAR(fromhex_doc,
 "bytearray.fromhex(string) -> bytearray\n\
 \n\
@@ -3209,7 +2857,7 @@ bytearray_methods[] = {
     {"rsplit", (PyCFunction)bytearray_rsplit, METH_VARARGS, rsplit__doc__},
     {"rstrip", (PyCFunction)bytearray_rstrip, METH_VARARGS, rstrip__doc__},
     {"split", (PyCFunction)bytearray_split, METH_VARARGS, split__doc__},
-    {"splitlines", (PyCFunction)stringlib_splitlines, METH_VARARGS,
+    {"splitlines", (PyCFunction)bytearray_splitlines, METH_VARARGS,
      splitlines__doc__},
     {"startswith", (PyCFunction)bytearray_startswith, METH_VARARGS ,
      startswith__doc__},
diff --git a/Objects/stringlib/README.txt b/Objects/stringlib/README.txt
index d948386..c884ec3 100644
--- a/Objects/stringlib/README.txt
+++ b/Objects/stringlib/README.txt
@@ -28,3 +28,12 @@ STRINGLIB_CHAR* STRINGLIB_STR(PyObject*)
 
     returns the pointer to the character data for the given string
     object (which must be of the right type)
+
+int STRINGLIB_CHECK_EXACT(PyObject *)
+
+    returns true if the object is an instance of our type, not a subclass.
+
+STRINGLIB_MUTABLE
+
+    Must be 0 or 1 to tell the cpp macros in stringlib code if the object
+    being operated on is mutable or not.
diff --git a/Objects/stringlib/count.h b/Objects/stringlib/count.h
index eba37e9..de34f96 100644
--- a/Objects/stringlib/count.h
+++ b/Objects/stringlib/count.h
@@ -9,28 +9,22 @@
 
 Py_LOCAL_INLINE(Py_ssize_t)
 stringlib_count(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
-                const STRINGLIB_CHAR* sub, Py_ssize_t sub_len)
+                const STRINGLIB_CHAR* sub, Py_ssize_t sub_len,
+                Py_ssize_t maxcount)
 {
     Py_ssize_t count;
 
     if (str_len < 0)
         return 0; /* start > len(str) */
     if (sub_len == 0)
-        return str_len + 1;
+        return (str_len < maxcount) ? str_len + 1 : maxcount;
 
-    count = fastsearch(str, str_len, sub, sub_len, FAST_COUNT);
+    count = fastsearch(str, str_len, sub, sub_len, maxcount, FAST_COUNT);
 
     if (count < 0)
-        count = 0; /* no match */
+        return 0; /* no match */
 
     return count;
 }
 
 #endif
-
-/*
-Local variables:
-c-basic-offset: 4
-indent-tabs-mode: nil
-End:
-*/
diff --git a/Objects/stringlib/ctype.h b/Objects/stringlib/ctype.h
index 8951276..739cf3d 100644
--- a/Objects/stringlib/ctype.h
+++ b/Objects/stringlib/ctype.h
@@ -107,4 +107,3 @@ stringlib_swapcase(PyObject *self)
                     STRINGLIB_LEN(self));
     return newobj;
 }
-
diff --git a/Objects/stringlib/fastsearch.h b/Objects/stringlib/fastsearch.h
index 7b9dd47..21cf3a2 100644
--- a/Objects/stringlib/fastsearch.h
+++ b/Objects/stringlib/fastsearch.h
@@ -18,10 +18,13 @@
 #define FAST_SEARCH 1
 #define FAST_RSEARCH 2
 
+#define BLOOM_ADD(mask, ch) ((mask |= (1 << ((ch) & (LONG_BIT - 1)))))
+#define BLOOM(mask, ch)     ((mask &  (1 << ((ch) & (LONG_BIT - 1)))))
+
 Py_LOCAL_INLINE(Py_ssize_t)
 fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
            const STRINGLIB_CHAR* p, Py_ssize_t m,
-           int mode)
+           Py_ssize_t maxcount, int mode)
 {
     long mask;
     Py_ssize_t skip, count = 0;
@@ -29,7 +32,7 @@ fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
 
     w = n - m;
 
-    if (w < 0)
+    if (w < 0 || (mode == FAST_COUNT && maxcount == 0))
         return -1;
 
     /* look for special cases */
@@ -39,8 +42,11 @@ fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
         /* use special case for 1-character strings */
         if (mode == FAST_COUNT) {
             for (i = 0; i < n; i++)
-                if (s[i] == p[0])
+                if (s[i] == p[0]) {
                     count++;
+                    if (count == maxcount)
+                        return maxcount;
+                }
             return count;
         } else if (mode == FAST_SEARCH) {
             for (i = 0; i < n; i++)
@@ -56,19 +62,20 @@ fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
 
     mlast = m - 1;
     skip = mlast - 1;
+    mask = 0;
 
     if (mode != FAST_RSEARCH) {
 
         /* create compressed boyer-moore delta 1 table */
 
         /* process pattern[:-1] */
-        for (mask = i = 0; i < mlast; i++) {
-            mask |= (1 << (p[i] & 0x1F));
+        for (i = 0; i < mlast; i++) {
+            BLOOM_ADD(mask, p[i]);
             if (p[i] == p[mlast])
                 skip = mlast - i - 1;
         }
         /* process pattern[-1] outside the loop */
-        mask |= (1 << (p[mlast] & 0x1F));
+        BLOOM_ADD(mask, p[mlast]);
 
         for (i = 0; i <= w; i++) {
             /* note: using mlast in the skip path slows things down on x86 */
@@ -82,17 +89,19 @@ fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
                     if (mode != FAST_COUNT)
                         return i;
                     count++;
+                    if (count == maxcount)
+                        return maxcount;
                     i = i + mlast;
                     continue;
                 }
                 /* miss: check if next character is part of pattern */
-                if (!(mask & (1 << (s[i+m] & 0x1F))))
+                if (!BLOOM(mask, s[i+m]))
                     i = i + m;
                 else
                     i = i + skip;
             } else {
                 /* skip: check if next character is part of pattern */
-                if (!(mask & (1 << (s[i+m] & 0x1F))))
+                if (!BLOOM(mask, s[i+m]))
                     i = i + m;
             }
         }
@@ -101,10 +110,10 @@ fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
         /* create compressed boyer-moore delta 1 table */
 
         /* process pattern[0] outside the loop */
-        mask = (1 << (p[0] & 0x1F));
+        BLOOM_ADD(mask, p[0]);
         /* process pattern[:0:-1] */
         for (i = mlast; i > 0; i--) {
-            mask |= (1 << (p[i] & 0x1F));
+            BLOOM_ADD(mask, p[i]);
             if (p[i] == p[0])
                 skip = i - 1;
         }
@@ -119,13 +128,13 @@ fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
                     /* got a match! */
                     return i;
                 /* miss: check if previous character is part of pattern */
-                if (!(mask & (1 << (s[i-1] & 0x1F))))
+                if (!BLOOM(mask, s[i-1]))
                     i = i - m;
                 else
                     i = i - skip;
             } else {
                 /* skip: check if previous character is part of pattern */
-                if (!(mask & (1 << (s[i-1] & 0x1F))))
+                if (!BLOOM(mask, s[i-1]))
                     i = i - m;
             }
         }
@@ -137,10 +146,3 @@ fastsearch(const STRINGLIB_CHAR* s, Py_ssize_t n,
 }
 
 #endif
-
-/*
-Local variables:
-c-basic-offset: 4
-indent-tabs-mode: nil
-End:
-*/
diff --git a/Objects/stringlib/find.h b/Objects/stringlib/find.h
index b5bace7..f915296c 100644
--- a/Objects/stringlib/find.h
+++ b/Objects/stringlib/find.h
@@ -19,7 +19,7 @@ stringlib_find(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
     if (sub_len == 0)
         return offset;
 
-    pos = fastsearch(str, str_len, sub, sub_len, FAST_SEARCH);
+    pos = fastsearch(str, str_len, sub, sub_len, -1, FAST_SEARCH);
 
     if (pos >= 0)
         pos += offset;
@@ -39,7 +39,7 @@ stringlib_rfind(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
     if (sub_len == 0)
         return str_len + offset;
 
-    pos = fastsearch(str, str_len, sub, sub_len, FAST_RSEARCH);
+    pos = fastsearch(str, str_len, sub, sub_len, -1, FAST_RSEARCH);
 
     if (pos >= 0)
         pos += offset;
@@ -47,22 +47,27 @@ stringlib_rfind(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
     return pos;
 }
 
+/* helper macro to fixup start/end slice values */
+#define ADJUST_INDICES(start, end, len)         \
+    if (end > len)                              \
+        end = len;                              \
+    else if (end < 0) {                         \
+        end += len;                             \
+        if (end < 0)                            \
+            end = 0;                            \
+    }                                           \
+    if (start < 0) {                            \
+        start += len;                           \
+        if (start < 0)                          \
+            start = 0;                          \
+    }
+
 Py_LOCAL_INLINE(Py_ssize_t)
 stringlib_find_slice(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
                      const STRINGLIB_CHAR* sub, Py_ssize_t sub_len,
                      Py_ssize_t start, Py_ssize_t end)
 {
-    if (start < 0)
-        start += str_len;
-    if (start < 0)
-        start = 0;
-    if (end > str_len)
-        end = str_len;
-    if (end < 0)
-        end += str_len;
-    if (end < 0)
-        end = 0;
-
+    ADJUST_INDICES(start, end, str_len);
     return stringlib_find(str + start, end - start, sub, sub_len, start);
 }
 
@@ -71,21 +76,11 @@ stringlib_rfind_slice(const STRINGLIB_CHAR* str, Py_ssize_t str_len,
                       const STRINGLIB_CHAR* sub, Py_ssize_t sub_len,
                       Py_ssize_t start, Py_ssize_t end)
 {
-    if (start < 0)
-        start += str_len;
-    if (start < 0)
-        start = 0;
-    if (end > str_len)
-        end = str_len;
-    if (end < 0)
-        end += str_len;
-    if (end < 0)
-        end = 0;
-
+    ADJUST_INDICES(start, end, str_len);
     return stringlib_rfind(str + start, end - start, sub, sub_len, start);
 }
 
-#if defined(STRINGLIB_STR) && !defined(FROM_BYTEARRAY)
+#ifdef STRINGLIB_WANT_CONTAINS_OBJ
 
 Py_LOCAL_INLINE(int)
 stringlib_contains_obj(PyObject* str, PyObject* sub)
@@ -96,9 +91,9 @@ stringlib_contains_obj(PyObject* str, PyObject* sub)
         ) != -1;
 }
 
-#endif /* STRINGLIB_STR */
+#endif /* STRINGLIB_WANT_CONTAINS_OBJ */
 
-#ifdef FROM_UNICODE
+#if STRINGLIB_IS_UNICODE
 
 /*
 This function is a helper for the "find" family (find, rfind, index,
@@ -146,13 +141,6 @@ _ParseTupleFinds (PyObject *args, PyObject **substring,
     return 1;
 }
 
-#endif /* FROM_UNICODE */
+#endif /* STRINGLIB_IS_UNICODE */
 
 #endif /* STRINGLIB_FIND_H */
-
-/*
-Local variables:
-c-basic-offset: 4
-indent-tabs-mode: nil
-End:
-*/
diff --git a/Objects/stringlib/partition.h b/Objects/stringlib/partition.h
index 2f26212..0170bdd 100644
--- a/Objects/stringlib/partition.h
+++ b/Objects/stringlib/partition.h
@@ -8,33 +8,39 @@
 #endif
 
 Py_LOCAL_INLINE(PyObject*)
-stringlib_partition(
-    PyObject* str_obj, const STRINGLIB_CHAR* str, Py_ssize_t str_len,
-    PyObject* sep_obj, const STRINGLIB_CHAR* sep, Py_ssize_t sep_len
-    )
+stringlib_partition(PyObject* str_obj,
+                    const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                    PyObject* sep_obj,
+                    const STRINGLIB_CHAR* sep, Py_ssize_t sep_len)
 {
     PyObject* out;
     Py_ssize_t pos;
 
     if (sep_len == 0) {
         PyErr_SetString(PyExc_ValueError, "empty separator");
-	return NULL;
+        return NULL;
     }
 
     out = PyTuple_New(3);
     if (!out)
-	return NULL;
+        return NULL;
 
-    pos = fastsearch(str, str_len, sep, sep_len, FAST_SEARCH);
+    pos = fastsearch(str, str_len, sep, sep_len, -1, FAST_SEARCH);
 
     if (pos < 0) {
-	Py_INCREF(str_obj);
-	PyTuple_SET_ITEM(out, 0, (PyObject*) str_obj);
-	Py_INCREF(STRINGLIB_EMPTY);
-	PyTuple_SET_ITEM(out, 1, (PyObject*) STRINGLIB_EMPTY);
-	Py_INCREF(STRINGLIB_EMPTY);
-	PyTuple_SET_ITEM(out, 2, (PyObject*) STRINGLIB_EMPTY);
-	return out;
+#if STRINGLIB_MUTABLE
+        PyTuple_SET_ITEM(out, 0, STRINGLIB_NEW(str, str_len));
+        PyTuple_SET_ITEM(out, 1, STRINGLIB_NEW(NULL, 0));
+        PyTuple_SET_ITEM(out, 2, STRINGLIB_NEW(NULL, 0));
+#else
+        Py_INCREF(str_obj);
+        PyTuple_SET_ITEM(out, 0, (PyObject*) str_obj);
+        Py_INCREF(STRINGLIB_EMPTY);
+        PyTuple_SET_ITEM(out, 1, (PyObject*) STRINGLIB_EMPTY);
+        Py_INCREF(STRINGLIB_EMPTY);
+        PyTuple_SET_ITEM(out, 2, (PyObject*) STRINGLIB_EMPTY);
+#endif
+        return out;
     }
 
     PyTuple_SET_ITEM(out, 0, STRINGLIB_NEW(str, pos));
@@ -44,41 +50,47 @@ stringlib_partition(
     PyTuple_SET_ITEM(out, 2, STRINGLIB_NEW(str + pos, str_len - pos));
 
     if (PyErr_Occurred()) {
-	Py_DECREF(out);
-	return NULL;
+        Py_DECREF(out);
+        return NULL;
     }
 
     return out;
 }
 
 Py_LOCAL_INLINE(PyObject*)
-stringlib_rpartition(
-    PyObject* str_obj, const STRINGLIB_CHAR* str, Py_ssize_t str_len,
-    PyObject* sep_obj, const STRINGLIB_CHAR* sep, Py_ssize_t sep_len
-    )
+stringlib_rpartition(PyObject* str_obj,
+                     const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                     PyObject* sep_obj,
+                     const STRINGLIB_CHAR* sep, Py_ssize_t sep_len)
 {
     PyObject* out;
     Py_ssize_t pos;
 
     if (sep_len == 0) {
         PyErr_SetString(PyExc_ValueError, "empty separator");
-	return NULL;
+        return NULL;
     }
 
     out = PyTuple_New(3);
     if (!out)
-	return NULL;
+        return NULL;
 
-    pos = fastsearch(str, str_len, sep, sep_len, FAST_RSEARCH);
+    pos = fastsearch(str, str_len, sep, sep_len, -1, FAST_RSEARCH);
 
     if (pos < 0) {
-	Py_INCREF(STRINGLIB_EMPTY);
-	PyTuple_SET_ITEM(out, 0, (PyObject*) STRINGLIB_EMPTY);
-	Py_INCREF(STRINGLIB_EMPTY);
-	PyTuple_SET_ITEM(out, 1, (PyObject*) STRINGLIB_EMPTY);
-	Py_INCREF(str_obj);
-	PyTuple_SET_ITEM(out, 2, (PyObject*) str_obj);
-	return out;
+#if STRINGLIB_MUTABLE
+        PyTuple_SET_ITEM(out, 0, STRINGLIB_NEW(NULL, 0));
+        PyTuple_SET_ITEM(out, 1, STRINGLIB_NEW(NULL, 0));
+        PyTuple_SET_ITEM(out, 2, STRINGLIB_NEW(str, str_len));
+#else
+        Py_INCREF(STRINGLIB_EMPTY);
+        PyTuple_SET_ITEM(out, 0, (PyObject*) STRINGLIB_EMPTY);
+        Py_INCREF(STRINGLIB_EMPTY);
+        PyTuple_SET_ITEM(out, 1, (PyObject*) STRINGLIB_EMPTY);
+        Py_INCREF(str_obj);
+        PyTuple_SET_ITEM(out, 2, (PyObject*) str_obj);
+#endif
+        return out;
     }
 
     PyTuple_SET_ITEM(out, 0, STRINGLIB_NEW(str, pos));
@@ -88,18 +100,11 @@ stringlib_rpartition(
     PyTuple_SET_ITEM(out, 2, STRINGLIB_NEW(str + pos, str_len - pos));
 
     if (PyErr_Occurred()) {
-	Py_DECREF(out);
-	return NULL;
+        Py_DECREF(out);
+        return NULL;
     }
 
     return out;
 }
 
 #endif
-
-/*
-Local variables:
-c-basic-offset: 4
-indent-tabs-mode: nil
-End:
-*/
diff --git a/Objects/stringlib/split.h b/Objects/stringlib/split.h
new file mode 100644
index 0000000..60e7767
--- /dev/null
+++ b/Objects/stringlib/split.h
@@ -0,0 +1,394 @@
+/* stringlib: split implementation */
+
+#ifndef STRINGLIB_SPLIT_H
+#define STRINGLIB_SPLIT_H
+
+#ifndef STRINGLIB_FASTSEARCH_H
+#error must include "stringlib/fastsearch.h" before including this module
+#endif
+
+/* Overallocate the initial list to reduce the number of reallocs for small
+   split sizes.  Eg, "A A A A A A A A A A".split() (10 elements) has three
+   resizes, to sizes 4, 8, then 16.  Most observed string splits are for human
+   text (roughly 11 words per line) and field delimited data (usually 1-10
+   fields).  For large strings the split algorithms are bandwidth limited
+   so increasing the preallocation likely will not improve things.*/
+
+#define MAX_PREALLOC 12
+
+/* 5 splits gives 6 elements */
+#define PREALLOC_SIZE(maxsplit) \
+    (maxsplit >= MAX_PREALLOC ? MAX_PREALLOC : maxsplit+1)
+
+#define SPLIT_APPEND(data, left, right)         \
+    sub = STRINGLIB_NEW((data) + (left),        \
+                        (right) - (left));      \
+    if (sub == NULL)                            \
+        goto onError;                           \
+    if (PyList_Append(list, sub)) {             \
+        Py_DECREF(sub);                         \
+        goto onError;                           \
+    }                                           \
+    else                                        \
+        Py_DECREF(sub);
+
+#define SPLIT_ADD(data, left, right) {          \
+    sub = STRINGLIB_NEW((data) + (left),        \
+                        (right) - (left));      \
+    if (sub == NULL)                            \
+        goto onError;                           \
+    if (count < MAX_PREALLOC) {                 \
+        PyList_SET_ITEM(list, count, sub);      \
+    } else {                                    \
+        if (PyList_Append(list, sub)) {         \
+            Py_DECREF(sub);                     \
+            goto onError;                       \
+        }                                       \
+        else                                    \
+            Py_DECREF(sub);                     \
+    }                                           \
+    count++; }
+
+
+/* Always force the list to the expected size. */
+#define FIX_PREALLOC_SIZE(list) Py_SIZE(list) = count
+
+Py_LOCAL_INLINE(PyObject *)
+stringlib_split_whitespace(PyObject* str_obj,
+                           const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                           Py_ssize_t maxcount)
+{
+    Py_ssize_t i, j, count=0;
+    PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
+    PyObject *sub;
+
+    if (list == NULL)
+        return NULL;
+
+    i = j = 0;
+    while (maxcount-- > 0) {
+        while (i < str_len && STRINGLIB_ISSPACE(str[i]))
+            i++;
+        if (i == str_len) break;
+        j = i; i++;
+        while (i < str_len && !STRINGLIB_ISSPACE(str[i]))
+            i++;
+#ifndef STRINGLIB_MUTABLE
+        if (j == 0 && i == str_len && STRINGLIB_CHECK_EXACT(str_obj)) {
+            /* No whitespace in str_obj, so just use it as list[0] */
+            Py_INCREF(str_obj);
+            PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
+            count++;
+            break;
+        }
+#endif
+        SPLIT_ADD(str, j, i);
+    }
+
+    if (i < str_len) {
+        /* Only occurs when maxcount was reached */
+        /* Skip any remaining whitespace and copy to end of string */
+        while (i < str_len && STRINGLIB_ISSPACE(str[i]))
+            i++;
+        if (i != str_len)
+            SPLIT_ADD(str, i, str_len);
+    }
+    FIX_PREALLOC_SIZE(list);
+    return list;
+
+  onError:
+    Py_DECREF(list);
+    return NULL;
+}
+
+Py_LOCAL_INLINE(PyObject *)
+stringlib_split_char(PyObject* str_obj,
+                     const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                     const STRINGLIB_CHAR ch,
+                     Py_ssize_t maxcount)
+{
+    Py_ssize_t i, j, count=0;
+    PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
+    PyObject *sub;
+
+    if (list == NULL)
+        return NULL;
+
+    i = j = 0;
+    while ((j < str_len) && (maxcount-- > 0)) {
+        for(; j < str_len; j++) {
+            /* I found that using memchr makes no difference */
+            if (str[j] == ch) {
+                SPLIT_ADD(str, i, j);
+                i = j = j + 1;
+                break;
+            }
+        }
+    }
+#ifndef STRINGLIB_MUTABLE
+    if (count == 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
+        /* ch not in str_obj, so just use str_obj as list[0] */
+        Py_INCREF(str_obj);
+        PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
+        count++;
+    } else
+#endif
+    if (i <= str_len) {
+        SPLIT_ADD(str, i, str_len);
+    }
+    FIX_PREALLOC_SIZE(list);
+    return list;
+
+  onError:
+    Py_DECREF(list);
+    return NULL;
+}
+
+Py_LOCAL_INLINE(PyObject *)
+stringlib_split(PyObject* str_obj,
+                const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                const STRINGLIB_CHAR* sep, Py_ssize_t sep_len,
+                Py_ssize_t maxcount)
+{
+    Py_ssize_t i, j, pos, count=0;
+    PyObject *list, *sub;
+
+    if (sep_len == 0) {
+        PyErr_SetString(PyExc_ValueError, "empty separator");
+        return NULL;
+    }
+    else if (sep_len == 1)
+        return stringlib_split_char(str_obj, str, str_len, sep[0], maxcount);
+
+    list = PyList_New(PREALLOC_SIZE(maxcount));
+    if (list == NULL)
+        return NULL;
+
+    i = j = 0;
+    while (maxcount-- > 0) {
+        pos = fastsearch(str+i, str_len-i, sep, sep_len, -1, FAST_SEARCH);
+        if (pos < 0)
+            break;
+        j = i + pos;
+        SPLIT_ADD(str, i, j);
+        i = j + sep_len;
+    }
+#ifndef STRINGLIB_MUTABLE
+    if (count == 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
+        /* No match in str_obj, so just use it as list[0] */
+        Py_INCREF(str_obj);
+        PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
+        count++;
+    } else
+#endif
+    {
+        SPLIT_ADD(str, i, str_len);
+    }
+    FIX_PREALLOC_SIZE(list);
+    return list;
+
+  onError:
+    Py_DECREF(list);
+    return NULL;
+}
+
+Py_LOCAL_INLINE(PyObject *)
+stringlib_rsplit_whitespace(PyObject* str_obj,
+                            const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                            Py_ssize_t maxcount)
+{
+    Py_ssize_t i, j, count=0;
+    PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
+    PyObject *sub;
+
+    if (list == NULL)
+        return NULL;
+
+    i = j = str_len - 1;
+    while (maxcount-- > 0) {
+        while (i >= 0 && STRINGLIB_ISSPACE(str[i]))
+            i--;
+        if (i < 0) break;
+        j = i; i--;
+        while (i >= 0 && !STRINGLIB_ISSPACE(str[i]))
+            i--;
+#ifndef STRINGLIB_MUTABLE
+        if (j == str_len - 1 && i < 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
+            /* No whitespace in str_obj, so just use it as list[0] */
+            Py_INCREF(str_obj);
+            PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
+            count++;
+            break;
+        }
+#endif
+        SPLIT_ADD(str, i + 1, j + 1);
+    }
+
+    if (i >= 0) {
+        /* Only occurs when maxcount was reached */
+        /* Skip any remaining whitespace and copy to beginning of string */
+        while (i >= 0 && STRINGLIB_ISSPACE(str[i]))
+            i--;
+        if (i >= 0)
+            SPLIT_ADD(str, 0, i + 1);
+    }
+    FIX_PREALLOC_SIZE(list);
+    if (PyList_Reverse(list) < 0)
+        goto onError;
+    return list;
+
+  onError:
+    Py_DECREF(list);
+    return NULL;
+}
+
+Py_LOCAL_INLINE(PyObject *)
+stringlib_rsplit_char(PyObject* str_obj,
+                      const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                      const STRINGLIB_CHAR ch,
+                      Py_ssize_t maxcount)
+{
+    Py_ssize_t i, j, count=0;
+    PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
+    PyObject *sub;
+
+    if (list == NULL)
+        return NULL;
+
+    i = j = str_len - 1;
+    while ((i >= 0) && (maxcount-- > 0)) {
+        for(; i >= 0; i--) {
+            if (str[i] == ch) {
+                SPLIT_ADD(str, i + 1, j + 1);
+                j = i = i - 1;
+                break;
+            }
+        }
+    }
+#ifndef STRINGLIB_MUTABLE
+    if (count == 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
+        /* ch not in str_obj, so just use str_obj as list[0] */
+        Py_INCREF(str_obj);
+        PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
+        count++;
+    } else
+#endif
+    if (j >= -1) {
+        SPLIT_ADD(str, 0, j + 1);
+    }
+    FIX_PREALLOC_SIZE(list);
+    if (PyList_Reverse(list) < 0)
+        goto onError;
+    return list;
+
+  onError:
+    Py_DECREF(list);
+    return NULL;
+}
+
+Py_LOCAL_INLINE(PyObject *)
+stringlib_rsplit(PyObject* str_obj,
+                 const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                 const STRINGLIB_CHAR* sep, Py_ssize_t sep_len,
+                 Py_ssize_t maxcount)
+{
+    Py_ssize_t j, pos, count=0;
+    PyObject *list, *sub;
+
+    if (sep_len == 0) {
+        PyErr_SetString(PyExc_ValueError, "empty separator");
+        return NULL;
+    }
+    else if (sep_len == 1)
+        return stringlib_rsplit_char(str_obj, str, str_len, sep[0], maxcount);
+
+    list = PyList_New(PREALLOC_SIZE(maxcount));
+    if (list == NULL)
+        return NULL;
+
+    j = str_len;
+    while (maxcount-- > 0) {
+        pos = fastsearch(str, j, sep, sep_len, -1, FAST_RSEARCH);
+        if (pos < 0)
+            break;
+        SPLIT_ADD(str, pos + sep_len, j);
+        j = pos;
+    }
+#ifndef STRINGLIB_MUTABLE
+    if (count == 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
+        /* No match in str_obj, so just use it as list[0] */
+        Py_INCREF(str_obj);
+        PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
+        count++;
+    } else
+#endif
+    {
+        SPLIT_ADD(str, 0, j);
+    }
+    FIX_PREALLOC_SIZE(list);
+    if (PyList_Reverse(list) < 0)
+        goto onError;
+    return list;
+
+  onError:
+    Py_DECREF(list);
+    return NULL;
+}
+
+Py_LOCAL_INLINE(PyObject *)
+stringlib_splitlines(PyObject* str_obj,
+                     const STRINGLIB_CHAR* str, Py_ssize_t str_len,
+                     int keepends)
+{
+    /* This does not use the preallocated list because splitlines is
+       usually run with hundreds of newlines.  The overhead of
+       switching between PyList_SET_ITEM and append causes about a
+       2-3% slowdown for that common case.  A smarter implementation
+       could move the if check out, so the SET_ITEMs are done first
+       and the appends only done when the prealloc buffer is full.
+       That's too much work for little gain.*/
+
+    register Py_ssize_t i;
+    register Py_ssize_t j;
+    PyObject *list = PyList_New(0);
+    PyObject *sub;
+
+    if (list == NULL)
+        return NULL;
+
+    for (i = j = 0; i < str_len; ) {
+        Py_ssize_t eol;
+
+        /* Find a line and append it */
+        while (i < str_len && !STRINGLIB_ISLINEBREAK(str[i]))
+            i++;
+
+        /* Skip the line break reading CRLF as one line break */
+        eol = i;
+        if (i < str_len) {
+            if (str[i] == '\r' && i + 1 < str_len && str[i+1] == '\n')
+                i += 2;
+            else
+                i++;
+            if (keepends)
+                eol = i;
+        }
+#ifndef STRINGLIB_MUTABLE
+        if (j == 0 && eol == str_len && STRINGLIB_CHECK_EXACT(str_obj)) {
+            /* No linebreak in str_obj, so just use it as list[0] */
+            if (PyList_Append(list, str_obj))
+                goto onError;
+            break;
+        }
+#endif
+        SPLIT_APPEND(str, j, eol);
+        j = i;
+    }
+    return list;
+
+  onError:
+    Py_DECREF(list);
+    return NULL;
+}
+
+#endif
diff --git a/Objects/stringlib/stringdefs.h b/Objects/stringlib/stringdefs.h
index 4a95258..84e4616 100644
--- a/Objects/stringlib/stringdefs.h
+++ b/Objects/stringlib/stringdefs.h
@@ -11,6 +11,8 @@
 #define STRINGLIB_TYPE_NAME      "string"
 #define STRINGLIB_PARSE_CODE     "S"
 #define STRINGLIB_EMPTY          nullstring
+#define STRINGLIB_ISSPACE        Py_ISSPACE
+#define STRINGLIB_ISLINEBREAK(x) ((x == '\n') || (x == '\r'))
 #define STRINGLIB_ISDECIMAL(x)   ((x >= '0') && (x <= '9'))
 #define STRINGLIB_TODECIMAL(x)   (STRINGLIB_ISDECIMAL(x) ? (x - '0') : -1)
 #define STRINGLIB_TOUPPER        Py_TOUPPER
@@ -21,8 +23,11 @@
 #define STRINGLIB_NEW            PyString_FromStringAndSize
 #define STRINGLIB_RESIZE         _PyString_Resize
 #define STRINGLIB_CHECK          PyString_Check
+#define STRINGLIB_CHECK_EXACT    PyString_CheckExact
 #define STRINGLIB_TOSTR          PyObject_Str
 #define STRINGLIB_GROUPING       _PyString_InsertThousandsGrouping
 #define STRINGLIB_GROUPING_LOCALE _PyString_InsertThousandsGroupingLocale
 
+#define STRINGLIB_WANT_CONTAINS_OBJ 1
+
 #endif /* !STRINGLIB_STRINGDEFS_H */
diff --git a/Objects/stringlib/transmogrify.h b/Objects/stringlib/transmogrify.h
index 7dc8177..1e132e5 100644
--- a/Objects/stringlib/transmogrify.h
+++ b/Objects/stringlib/transmogrify.h
@@ -1,13 +1,6 @@
 /* NOTE: this API is -ONLY- for use with single byte character strings. */
 /* Do not use it with Unicode. */
 
-#include "bytes_methods.h"
-
-#ifndef STRINGLIB_MUTABLE
-#warning "STRINGLIB_MUTABLE not defined before #include, assuming 0"
-#define STRINGLIB_MUTABLE 0
-#endif
-
 /* the more complicated methods.  parts of these should be pulled out into the
    shared code in bytes_methods.c to cut down on duplicate code bloat.  */
 
@@ -269,87 +262,3 @@ stringlib_zfill(PyObject *self, PyObject *args)
 
     return (PyObject*) s;
 }
-
-
-#define _STRINGLIB_SPLIT_APPEND(data, left, right)		\
-	str = STRINGLIB_NEW((data) + (left),	                \
-					 (right) - (left));	\
-	if (str == NULL)					\
-		goto onError;					\
-	if (PyList_Append(list, str)) {				\
-		Py_DECREF(str);					\
-		goto onError;					\
-	}							\
-	else							\
-		Py_DECREF(str);
-
-PyDoc_STRVAR(splitlines__doc__,
-"B.splitlines([keepends]) -> list of lines\n\
-\n\
-Return a list of the lines in B, breaking at line boundaries.\n\
-Line breaks are not included in the resulting list unless keepends\n\
-is given and true.");
-
-static PyObject*
-stringlib_splitlines(PyObject *self, PyObject *args)
-{
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len;
-    int keepends = 0;
-    PyObject *list;
-    PyObject *str;
-    char *data;
-
-    if (!PyArg_ParseTuple(args, "|i:splitlines", &keepends))
-        return NULL;
-
-    data = STRINGLIB_STR(self);
-    len = STRINGLIB_LEN(self);
-
-    /* This does not use the preallocated list because splitlines is
-       usually run with hundreds of newlines.  The overhead of
-       switching between PyList_SET_ITEM and append causes about a
-       2-3% slowdown for that common case.  A smarter implementation
-       could move the if check out, so the SET_ITEMs are done first
-       and the appends only done when the prealloc buffer is full.
-       That's too much work for little gain.*/
-
-    list = PyList_New(0);
-    if (!list)
-        goto onError;
-
-    for (i = j = 0; i < len; ) {
-	Py_ssize_t eol;
-
-	/* Find a line and append it */
-	while (i < len && data[i] != '\n' && data[i] != '\r')
-	    i++;
-
-	/* Skip the line break reading CRLF as one line break */
-	eol = i;
-	if (i < len) {
-	    if (data[i] == '\r' && i + 1 < len &&
-		data[i+1] == '\n')
-		i += 2;
-	    else
-		i++;
-	    if (keepends)
-		eol = i;
-	}
-	_STRINGLIB_SPLIT_APPEND(data, j, eol);
-	j = i;
-    }
-    if (j < len) {
-	_STRINGLIB_SPLIT_APPEND(data, j, len);
-    }
-
-    return list;
-
- onError:
-    Py_XDECREF(list);
-    return NULL;
-}
-
-#undef _STRINGLIB_SPLIT_APPEND
-
diff --git a/Objects/stringlib/unicodedefs.h b/Objects/stringlib/unicodedefs.h
index 524781f..dd814f6 100644
--- a/Objects/stringlib/unicodedefs.h
+++ b/Objects/stringlib/unicodedefs.h
@@ -11,6 +11,8 @@
 #define STRINGLIB_TYPE_NAME      "unicode"
 #define STRINGLIB_PARSE_CODE     "U"
 #define STRINGLIB_EMPTY          unicode_empty
+#define STRINGLIB_ISSPACE        Py_UNICODE_ISSPACE
+#define STRINGLIB_ISLINEBREAK    BLOOM_LINEBREAK
 #define STRINGLIB_ISDECIMAL      Py_UNICODE_ISDECIMAL
 #define STRINGLIB_TODECIMAL      Py_UNICODE_TODECIMAL
 #define STRINGLIB_TOUPPER        Py_UNICODE_TOUPPER
@@ -21,6 +23,7 @@
 #define STRINGLIB_NEW            PyUnicode_FromUnicode
 #define STRINGLIB_RESIZE         PyUnicode_Resize
 #define STRINGLIB_CHECK          PyUnicode_Check
+#define STRINGLIB_CHECK_EXACT    PyUnicode_CheckExact
 #define STRINGLIB_GROUPING       _PyUnicode_InsertThousandsGrouping
 
 #if PY_VERSION_HEX < 0x03000000
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 0f3874e..43ef3fa 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -841,6 +841,7 @@ PyString_AsStringAndSize(register PyObject *obj,
 #include "stringlib/count.h"
 #include "stringlib/find.h"
 #include "stringlib/partition.h"
+#include "stringlib/split.h"
 
 #define _Py_InsertThousandsGrouping _PyString_InsertThousandsGrouping
 #include "stringlib/localeutil.h"
@@ -1425,145 +1426,6 @@ static const char *stripformat[] = {"|O:lstrip", "|O:rstrip", "|O:strip"};
 
 #define STRIPNAME(i) (stripformat[i]+3)
 
-
-/* Don't call if length < 2 */
-#define Py_STRING_MATCH(target, offset, pattern, length)	\
-  (target[offset] == pattern[0] &&				\
-   target[offset+length-1] == pattern[length-1] &&		\
-   !memcmp(target+offset+1, pattern+1, length-2) )
-
-
-/* Overallocate the initial list to reduce the number of reallocs for small
-   split sizes.  Eg, "A A A A A A A A A A".split() (10 elements) has three
-   resizes, to sizes 4, 8, then 16.  Most observed string splits are for human
-   text (roughly 11 words per line) and field delimited data (usually 1-10
-   fields).  For large strings the split algorithms are bandwidth limited
-   so increasing the preallocation likely will not improve things.*/
-
-#define MAX_PREALLOC 12
-
-/* 5 splits gives 6 elements */
-#define PREALLOC_SIZE(maxsplit) \
-	(maxsplit >= MAX_PREALLOC ? MAX_PREALLOC : maxsplit+1)
-
-#define SPLIT_APPEND(data, left, right)				\
-	str = PyString_FromStringAndSize((data) + (left),	\
-					 (right) - (left));	\
-	if (str == NULL)					\
-		goto onError;					\
-	if (PyList_Append(list, str)) {				\
-		Py_DECREF(str);					\
-		goto onError;					\
-	}							\
-	else							\
-		Py_DECREF(str);
-
-#define SPLIT_ADD(data, left, right) {				\
-	str = PyString_FromStringAndSize((data) + (left),	\
-					 (right) - (left));	\
-	if (str == NULL)					\
-		goto onError;					\
-	if (count < MAX_PREALLOC) {				\
-		PyList_SET_ITEM(list, count, str);		\
-	} else {						\
-		if (PyList_Append(list, str)) {			\
-			Py_DECREF(str);				\
-			goto onError;				\
-		}						\
-		else						\
-			Py_DECREF(str);				\
-	}							\
-	count++; }
-
-/* Always force the list to the expected size. */
-#define FIX_PREALLOC_SIZE(list) Py_SIZE(list) = 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--; }
-
-Py_LOCAL_INLINE(PyObject *)
-split_whitespace(PyStringObject *self, Py_ssize_t len, Py_ssize_t maxsplit)
-{
-	const char *s = PyString_AS_STRING(self);
-	Py_ssize_t i, j, count=0;
-	PyObject *str;
-	PyObject *list = PyList_New(PREALLOC_SIZE(maxsplit));
-
-	if (list == NULL)
-		return NULL;
-
-	i = j = 0;
-
-	while (maxsplit-- > 0) {
-		SKIP_SPACE(s, i, len);
-		if (i==len) break;
-		j = i; i++;
-		SKIP_NONSPACE(s, i, len);
-		if (j == 0 && i == len && PyString_CheckExact(self)) {
-			/* No whitespace in self, so just use it as list[0] */
-			Py_INCREF(self);
-			PyList_SET_ITEM(list, 0, (PyObject *)self);
-			count++;
-			break;
-		}
-		SPLIT_ADD(s, j, i);
-	}
-
-	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;
-  onError:
-	Py_DECREF(list);
-	return NULL;
-}
-
-Py_LOCAL_INLINE(PyObject *)
-split_char(PyStringObject *self, Py_ssize_t len, char ch, Py_ssize_t maxcount)
-{
-	const char *s = PyString_AS_STRING(self);
-	register Py_ssize_t i, j, count=0;
-	PyObject *str;
-	PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
-
-	if (list == NULL)
-		return NULL;
-
-	i = j = 0;
-	while ((j < len) && (maxcount-- > 0)) {
-		for(; j<len; j++) {
-			/* I found that using memchr makes no difference */
-			if (s[j] == ch) {
-				SPLIT_ADD(s, i, j);
-				i = j = j + 1;
-				break;
-			}
-		}
-	}
-	if (i == 0 && count == 0 && PyString_CheckExact(self)) {
-		/* ch not in self, so just use self as list[0] */
-		Py_INCREF(self);
-		PyList_SET_ITEM(list, 0, (PyObject *)self);
-		count++;
-	}
-	else if (i <= len) {
-		SPLIT_ADD(s, i, len);
-	}
-	FIX_PREALLOC_SIZE(list);
-	return list;
-
-  onError:
-	Py_DECREF(list);
-	return NULL;
-}
-
 PyDoc_STRVAR(split__doc__,
 "S.split([sep [,maxsplit]]) -> list of strings\n\
 \n\
@@ -1576,17 +1438,17 @@ from the result.");
 static PyObject *
 string_split(PyStringObject *self, PyObject *args)
 {
-	Py_ssize_t len = PyString_GET_SIZE(self), n, i, j, pos;
-	Py_ssize_t maxsplit = -1, count=0;
+	Py_ssize_t len = PyString_GET_SIZE(self), n;
+	Py_ssize_t maxsplit = -1;
 	const char *s = PyString_AS_STRING(self), *sub;
-	PyObject *list, *str, *subobj = Py_None;
+	PyObject *subobj = Py_None;
 
 	if (!PyArg_ParseTuple(args, "|On:split", &subobj, &maxsplit))
 		return NULL;
 	if (maxsplit < 0)
 		maxsplit = PY_SSIZE_T_MAX;
 	if (subobj == Py_None)
-		return split_whitespace(self, len, maxsplit);
+		return stringlib_split_whitespace((PyObject*) self, s, len, maxsplit);
 	if (PyString_Check(subobj)) {
 		sub = PyString_AS_STRING(subobj);
 		n = PyString_GET_SIZE(subobj);
@@ -1598,33 +1460,7 @@ string_split(PyStringObject *self, PyObject *args)
 	else if (PyObject_AsCharBuffer(subobj, &sub, &n))
 		return NULL;
 
-	if (n == 0) {
-		PyErr_SetString(PyExc_ValueError, "empty separator");
-		return NULL;
-	}
-	else if (n == 1)
-		return split_char(self, len, sub[0], maxsplit);
-
-	list = PyList_New(PREALLOC_SIZE(maxsplit));
-	if (list == NULL)
-		return NULL;
-
-	i = j = 0;
-	while (maxsplit-- > 0) {
-		pos = fastsearch(s+i, len-i, sub, n, FAST_SEARCH);
-		if (pos < 0)
-			break;
-		j = i + pos;
-		SPLIT_ADD(s, i, j);
-		i = j + n;
-	}
-	SPLIT_ADD(s, i, len);
-	FIX_PREALLOC_SIZE(list);
-	return list;
-
- onError:
-	Py_DECREF(list);
-	return NULL;
+	return stringlib_split((PyObject*) self, s, len, sub, n, maxsplit);
 }
 
 PyDoc_STRVAR(partition__doc__,
@@ -1689,90 +1525,6 @@ string_rpartition(PyStringObject *self, PyObject *sep_obj)
 		);
 }
 
-Py_LOCAL_INLINE(PyObject *)
-rsplit_whitespace(PyStringObject *self, Py_ssize_t len, Py_ssize_t maxsplit)
-{
-	const char *s = PyString_AS_STRING(self);
-	Py_ssize_t i, j, count=0;
-	PyObject *str;
-	PyObject *list = PyList_New(PREALLOC_SIZE(maxsplit));
-
-	if (list == NULL)
-		return NULL;
-
-	i = j = len-1;
-
-	while (maxsplit-- > 0) {
-		RSKIP_SPACE(s, i);
-		if (i<0) break;
-		j = i; i--;
-		RSKIP_NONSPACE(s, i);
-		if (j == len-1 && i < 0 && PyString_CheckExact(self)) {
-			/* No whitespace in self, so just use it as list[0] */
-			Py_INCREF(self);
-			PyList_SET_ITEM(list, 0, (PyObject *)self);
-			count++;
-			break;
-		}
-		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)
-		goto onError;
-	return list;
-  onError:
-	Py_DECREF(list);
-	return NULL;
-}
-
-Py_LOCAL_INLINE(PyObject *)
-rsplit_char(PyStringObject *self, Py_ssize_t len, char ch, Py_ssize_t maxcount)
-{
-	const char *s = PyString_AS_STRING(self);
-	register Py_ssize_t i, j, count=0;
-	PyObject *str;
-	PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
-
-	if (list == NULL)
-		return NULL;
-
-	i = j = len - 1;
-	while ((i >= 0) && (maxcount-- > 0)) {
-		for (; i >= 0; i--) {
-			if (s[i] == ch) {
-				SPLIT_ADD(s, i + 1, j + 1);
-				j = i = i - 1;
-				break;
-			}
-		}
-	}
-	if (i < 0 && count == 0 && PyString_CheckExact(self)) {
-		/* ch not in self, so just use self as list[0] */
-		Py_INCREF(self);
-		PyList_SET_ITEM(list, 0, (PyObject *)self);
-		count++;
-	}
-	else if (j >= -1) {
-		SPLIT_ADD(s, 0, j + 1);
-	}
-	FIX_PREALLOC_SIZE(list);
-	if (PyList_Reverse(list) < 0)
-		goto onError;
-	return list;
-
- onError:
-	Py_DECREF(list);
-	return NULL;
-}
-
 PyDoc_STRVAR(rsplit__doc__,
 "S.rsplit([sep [,maxsplit]]) -> list of strings\n\
 \n\
@@ -1785,17 +1537,17 @@ is a separator.");
 static PyObject *
 string_rsplit(PyStringObject *self, PyObject *args)
 {
-	Py_ssize_t len = PyString_GET_SIZE(self), n, j, pos;
-	Py_ssize_t maxsplit = -1, count=0;
+	Py_ssize_t len = PyString_GET_SIZE(self), n;
+	Py_ssize_t maxsplit = -1;
 	const char *s = PyString_AS_STRING(self), *sub;
-	PyObject *list, *str, *subobj = Py_None;
+	PyObject *subobj = Py_None;
 
 	if (!PyArg_ParseTuple(args, "|On:rsplit", &subobj, &maxsplit))
 		return NULL;
 	if (maxsplit < 0)
 		maxsplit = PY_SSIZE_T_MAX;
 	if (subobj == Py_None)
-		return rsplit_whitespace(self, len, maxsplit);
+		return stringlib_rsplit_whitespace((PyObject*) self, s, len, maxsplit);
 	if (PyString_Check(subobj)) {
 		sub = PyString_AS_STRING(subobj);
 		n = PyString_GET_SIZE(subobj);
@@ -1807,35 +1559,7 @@ string_rsplit(PyStringObject *self, PyObject *args)
 	else if (PyObject_AsCharBuffer(subobj, &sub, &n))
 		return NULL;
 
-	if (n == 0) {
-		PyErr_SetString(PyExc_ValueError, "empty separator");
-		return NULL;
-	}
-	else if (n == 1)
-		return rsplit_char(self, len, sub[0], maxsplit);
-
-	list = PyList_New(PREALLOC_SIZE(maxsplit));
-	if (list == NULL)
-		return NULL;
-
-	j = len;
-
-	while (maxsplit-- > 0) {
-		pos = fastsearch(s, j, sub, n, FAST_RSEARCH);
-		if (pos < 0)
-			break;
-		SPLIT_ADD(s, pos + n, j);
-		j = pos;
-	}
-	SPLIT_ADD(s, 0, j);
-	FIX_PREALLOC_SIZE(list);
-	if (PyList_Reverse(list) < 0)
-		goto onError;
-	return list;
-
-onError:
-	Py_DECREF(list);
-	return NULL;
+	return stringlib_rsplit((PyObject*) self, s, len, sub, n, maxsplit);
 }
 
 
@@ -1950,20 +1674,20 @@ _PyString_Join(PyObject *sep, PyObject *x)
 	return string_join((PyStringObject *)sep, x);
 }
 
-Py_LOCAL_INLINE(void)
-string_adjust_indices(Py_ssize_t *start, Py_ssize_t *end, Py_ssize_t len)
-{
-	if (*end > len)
-		*end = len;
-	else if (*end < 0)
-		*end += len;
-	if (*end < 0)
-		*end = 0;
-	if (*start < 0)
-		*start += len;
-	if (*start < 0)
-		*start = 0;
-}
+/* helper macro to fixup start/end slice values */
+#define ADJUST_INDICES(start, end, len)         \
+	if (end > len)                          \
+	    end = len;                          \
+	else if (end < 0) {                     \
+	    end += len;                         \
+	    if (end < 0)                        \
+	        end = 0;                        \
+	}                                       \
+	if (start < 0) {                        \
+	    start += len;                       \
+	    if (start < 0)                      \
+	        start = 0;                      \
+	}
 
 Py_LOCAL_INLINE(Py_ssize_t)
 string_find_internal(PyStringObject *self, PyObject *args, int dir)
@@ -2417,10 +2141,10 @@ string_count(PyStringObject *self, PyObject *args)
 	else if (PyObject_AsCharBuffer(sub_obj, &sub, &sub_len))
 		return NULL;
 
-	string_adjust_indices(&start, &end, PyString_GET_SIZE(self));
+	ADJUST_INDICES(start, end, PyString_GET_SIZE(self));
 
 	return PyInt_FromSsize_t(
-		stringlib_count(str + start, end - start, sub, sub_len)
+		stringlib_count(str + start, end - start, sub, sub_len, PY_SSIZE_T_MAX)
 		);
 }
 
@@ -2583,9 +2307,6 @@ string_translate(PyStringObject *self, PyObject *args)
 }
 
 
-#define FORWARD 1
-#define REVERSE -1
-
 /* find and count characters and substrings */
 
 #define findchar(target, target_len, c)				\
@@ -2621,93 +2342,6 @@ countchar(const char *target, int target_len, char c, Py_ssize_t maxcount)
 	return count;
 }
 
-Py_LOCAL(Py_ssize_t)
-findstring(const char *target, Py_ssize_t target_len,
-	   const char *pattern, Py_ssize_t pattern_len,
-	   Py_ssize_t start,
-	   Py_ssize_t end,
-	   int direction)
-{
-	if (start < 0) {
-		start += target_len;
-		if (start < 0)
-			start = 0;
-	}
-	if (end > target_len) {
-		end = target_len;
-	} else if (end < 0) {
-		end += target_len;
-		if (end < 0)
-			end = 0;
-	}
-
-	/* zero-length substrings always match at the first attempt */
-	if (pattern_len == 0)
-		return (direction > 0) ? start : end;
-
-	end -= pattern_len;
-
-	if (direction < 0) {
-		for (; end >= start; end--)
-			if (Py_STRING_MATCH(target, end, pattern, pattern_len))
-				return end;
-	} else {
-		for (; start <= end; start++)
-			if (Py_STRING_MATCH(target, start, pattern, pattern_len))
-				return start;
-	}
-	return -1;
-}
-
-Py_LOCAL_INLINE(Py_ssize_t)
-countstring(const char *target, Py_ssize_t target_len,
-	    const char *pattern, Py_ssize_t pattern_len,
-	    Py_ssize_t start,
-	    Py_ssize_t end,
-	    int direction, Py_ssize_t maxcount)
-{
-	Py_ssize_t count=0;
-
-	if (start < 0) {
-		start += target_len;
-		if (start < 0)
-			start = 0;
-	}
-	if (end > target_len) {
-		end = target_len;
-	} else if (end < 0) {
-		end += target_len;
-		if (end < 0)
-			end = 0;
-	}
-
-	/* zero-length substrings match everywhere */
-	if (pattern_len == 0 || maxcount == 0) {
-		if (target_len+1 < maxcount)
-			return target_len+1;
-		return maxcount;
-	}
-
-	end -= pattern_len;
-	if (direction < 0) {
-		for (; (end >= start); end--)
-			if (Py_STRING_MATCH(target, end, pattern, pattern_len)) {
-				count++;
-				if (--maxcount <= 0) break;
-				end -= pattern_len-1;
-			}
-	} else {
-		for (; (start <= end); start++)
-			if (Py_STRING_MATCH(target, start, pattern, pattern_len)) {
-				count++;
-				if (--maxcount <= 0)
-					break;
-				start += pattern_len-1;
-			}
-	}
-	return count;
-}
-
 
 /* Algorithms for different cases of string replacement */
 
@@ -2828,10 +2462,9 @@ replace_delete_substring(PyStringObject *self,
 	self_len = PyString_GET_SIZE(self);
 	self_s = PyString_AS_STRING(self);
 
-	count = countstring(self_s, self_len,
-			    from_s, from_len,
-			    0, self_len, 1,
-			    maxcount);
+	count = stringlib_count(self_s, self_len,
+	                        from_s, from_len,
+	                        maxcount);
 
 	if (count == 0) {
 		/* no matches */
@@ -2850,9 +2483,9 @@ replace_delete_substring(PyStringObject *self,
 	start = self_s;
 	end = self_s + self_len;
 	while (count-- > 0) {
-		offset = findstring(start, end-start,
-				    from_s, from_len,
-				    0, end-start, FORWARD);
+		offset = stringlib_find(start, end-start,
+		                        from_s, from_len,
+		                        0);
 		if (offset == -1)
 			break;
 		next = start + offset;
@@ -2928,9 +2561,9 @@ replace_substring_in_place(PyStringObject *self,
 	self_s = PyString_AS_STRING(self);
 	self_len = PyString_GET_SIZE(self);
 
-	offset = findstring(self_s, self_len,
-			    from_s, from_len,
-			    0, self_len, FORWARD);
+	offset = stringlib_find(self_s, self_len,
+	                        from_s, from_len,
+	                        0);
 	if (offset == -1) {
 		/* No matches; return the original string */
 		return return_self(self);
@@ -2950,9 +2583,9 @@ replace_substring_in_place(PyStringObject *self,
 	end = result_s + self_len;
 
 	while ( --maxcount > 0) {
-		offset = findstring(start, end-start,
-				    from_s, from_len,
-				    0, end-start, FORWARD);
+		offset = stringlib_find(start, end-start,
+		                        from_s, from_len,
+		                        0);
 		if (offset==-1)
 			break;
 		Py_MEMCPY(start+offset, to_s, from_len);
@@ -3044,9 +2677,10 @@ replace_substring(PyStringObject *self,
 	self_s = PyString_AS_STRING(self);
 	self_len = PyString_GET_SIZE(self);
 
-	count = countstring(self_s, self_len,
-			    from_s, from_len,
-			    0, self_len, FORWARD, maxcount);
+	count = stringlib_count(self_s, self_len,
+	                        from_s, from_len,
+	                        maxcount);
+
 	if (count == 0) {
 		/* no matches, return unchanged */
 		return return_self(self);
@@ -3073,9 +2707,9 @@ replace_substring(PyStringObject *self,
 	start = self_s;
 	end = self_s + self_len;
 	while (count-- > 0) {
-		offset = findstring(start, end-start,
-				    from_s, from_len,
-				    0, end-start, FORWARD);
+		offset = stringlib_find(start, end-start,
+		                        from_s, from_len,
+		                        0);
 		if (offset == -1)
 			break;
 		next = start+offset;
@@ -3245,7 +2879,7 @@ _string_tailmatch(PyStringObject *self, PyObject *substr, Py_ssize_t start,
 		return -1;
 	str = PyString_AS_STRING(self);
 
-	string_adjust_indices(&start, &end, len);
+	ADJUST_INDICES(start, end, len);
 
 	if (direction < 0) {
 		/* startswith */
@@ -3913,62 +3547,15 @@ is given and true.");
 static PyObject*
 string_splitlines(PyStringObject *self, PyObject *args)
 {
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len;
     int keepends = 0;
-    PyObject *list;
-    PyObject *str;
-    char *data;
 
     if (!PyArg_ParseTuple(args, "|i:splitlines", &keepends))
         return NULL;
 
-    data = PyString_AS_STRING(self);
-    len = PyString_GET_SIZE(self);
-
-    /* This does not use the preallocated list because splitlines is
-       usually run with hundreds of newlines.  The overhead of
-       switching between PyList_SET_ITEM and append causes about a
-       2-3% slowdown for that common case.  A smarter implementation
-       could move the if check out, so the SET_ITEMs are done first
-       and the appends only done when the prealloc buffer is full.
-       That's too much work for little gain.*/
-
-    list = PyList_New(0);
-    if (!list)
-        goto onError;
-
-    for (i = j = 0; i < len; ) {
-	Py_ssize_t eol;
-
-	/* Find a line and append it */
-	while (i < len && data[i] != '\n' && data[i] != '\r')
-	    i++;
-
-	/* Skip the line break reading CRLF as one line break */
-	eol = i;
-	if (i < len) {
-	    if (data[i] == '\r' && i + 1 < len &&
-		data[i+1] == '\n')
-		i += 2;
-	    else
-		i++;
-	    if (keepends)
-		eol = i;
-	}
-	SPLIT_APPEND(data, j, eol);
-	j = i;
-    }
-    if (j < len) {
-	SPLIT_APPEND(data, j, len);
-    }
-
-    return list;
-
- onError:
-    Py_XDECREF(list);
-    return NULL;
+    return stringlib_splitlines(
+        (PyObject*) self, PyString_AS_STRING(self), PyString_GET_SIZE(self),
+        keepends
+        );
 }
 
 PyDoc_STRVAR(sizeof__doc__,
@@ -3982,11 +3569,6 @@ string_sizeof(PyStringObject *v)
 	return PyInt_FromSsize_t(res);
 }
 
-#undef SPLIT_APPEND
-#undef SPLIT_ADD
-#undef MAX_PREALLOC
-#undef PREALLOC_SIZE
-
 static PyObject *
 string_getnewargs(PyStringObject *v)
 {
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index 79e824e..b7874f1 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -194,7 +194,8 @@ PyUnicode_GetMax(void)
 
 static BLOOM_MASK bloom_linebreak;
 
-#define BLOOM(mask, ch) ((mask & (1 << ((ch) & 0x1F))))
+#define BLOOM_ADD(mask, ch) ((mask |= (1 << ((ch) & (LONG_BIT - 1)))))
+#define BLOOM(mask, ch)     ((mask &  (1 << ((ch) & (LONG_BIT - 1)))))
 
 #define BLOOM_LINEBREAK(ch)                                             \
     ((ch) < 128U ? ascii_linebreak[(ch)] :                              \
@@ -209,7 +210,7 @@ Py_LOCAL_INLINE(BLOOM_MASK) make_bloom_mask(Py_UNICODE* ptr, Py_ssize_t len)
 
     mask = 0;
     for (i = 0; i < len; i++)
-        mask |= (1 << (ptr[i] & 0x1F));
+        BLOOM_ADD(mask, ptr[i]);
 
     return mask;
 }
@@ -5245,27 +5246,27 @@ int PyUnicode_EncodeDecimal(Py_UNICODE *s,
 /* --- Helpers ------------------------------------------------------------ */
 
 #include "stringlib/unicodedefs.h"
-
-#define FROM_UNICODE
-
 #include "stringlib/fastsearch.h"
 
 #include "stringlib/count.h"
 #include "stringlib/find.h"
 #include "stringlib/partition.h"
+#include "stringlib/split.h"
 
 /* helper macro to fixup start/end slice values */
-#define FIX_START_END(obj)                      \
-    if (start < 0)                              \
-        start += (obj)->length;                 \
-    if (start < 0)                              \
-        start = 0;                              \
-    if (end > (obj)->length)                    \
-        end = (obj)->length;                    \
-    if (end < 0)                                \
-        end += (obj)->length;                   \
-    if (end < 0)                                \
-        end = 0;
+#define ADJUST_INDICES(start, end, len)         \
+    if (end > len)                              \
+        end = len;                              \
+    else if (end < 0) {                         \
+        end += len;                             \
+        if (end < 0)                            \
+            end = 0;                            \
+    }                                           \
+    if (start < 0) {                            \
+        start += len;                           \
+        if (start < 0)                          \
+            start = 0;                          \
+    }
 
 Py_ssize_t PyUnicode_Count(PyObject *str,
                            PyObject *substr,
@@ -5285,10 +5286,10 @@ Py_ssize_t PyUnicode_Count(PyObject *str,
         return -1;
     }
 
-    FIX_START_END(str_obj);
-
+    ADJUST_INDICES(start, end, str_obj->length);
     result = stringlib_count(
-        str_obj->str + start, end - start, sub_obj->str, sub_obj->length
+        str_obj->str + start, end - start, sub_obj->str, sub_obj->length,
+        PY_SSIZE_T_MAX
         );
 
     Py_DECREF(sub_obj);
@@ -5343,8 +5344,7 @@ int tailmatch(PyUnicodeObject *self,
     if (substring->length == 0)
         return 1;
 
-    FIX_START_END(self);
-
+    ADJUST_INDICES(start, end, self->length);
     end -= substring->length;
     if (end < start)
         return 0;
@@ -5721,305 +5721,40 @@ PyUnicodeObject *pad(PyUnicodeObject *self,
     return u;
 }
 
-#define SPLIT_APPEND(data, left, right)                                 \
-    str = PyUnicode_FromUnicode((data) + (left), (right) - (left));     \
-    if (!str)                                                           \
-        goto onError;                                                   \
-    if (PyList_Append(list, str)) {                                     \
-        Py_DECREF(str);                                                 \
-        goto onError;                                                   \
-    }                                                                   \
-    else                                                                \
-        Py_DECREF(str);
-
-static
-PyObject *split_whitespace(PyUnicodeObject *self,
-                           PyObject *list,
-                           Py_ssize_t maxcount)
-{
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len = self->length;
-    PyObject *str;
-    register const Py_UNICODE *buf = self->str;
-
-    for (i = j = 0; i < len; ) {
-        /* find a token */
-        while (i < len && Py_UNICODE_ISSPACE(buf[i]))
-            i++;
-        j = i;
-        while (i < len && !Py_UNICODE_ISSPACE(buf[i]))
-            i++;
-        if (j < i) {
-            if (maxcount-- <= 0)
-                break;
-            SPLIT_APPEND(buf, j, i);
-            while (i < len && Py_UNICODE_ISSPACE(buf[i]))
-                i++;
-            j = i;
-        }
-    }
-    if (j < len) {
-        SPLIT_APPEND(buf, j, len);
-    }
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
-}
-
-PyObject *PyUnicode_Splitlines(PyObject *string,
-                               int keepends)
+PyObject *PyUnicode_Splitlines(PyObject *string, int keepends)
 {
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len;
     PyObject *list;
-    PyObject *str;
-    Py_UNICODE *data;
 
     string = PyUnicode_FromObject(string);
     if (string == NULL)
         return NULL;
-    data = PyUnicode_AS_UNICODE(string);
-    len = PyUnicode_GET_SIZE(string);
-
-    list = PyList_New(0);
-    if (!list)
-        goto onError;
 
-    for (i = j = 0; i < len; ) {
-        Py_ssize_t eol;
+    list = stringlib_splitlines(
+        (PyObject*) string, PyUnicode_AS_UNICODE(string),
+        PyUnicode_GET_SIZE(string), keepends);
 
-        /* Find a line and append it */
-        while (i < len && !BLOOM_LINEBREAK(data[i]))
-            i++;
-
-        /* Skip the line break reading CRLF as one line break */
-        eol = i;
-        if (i < len) {
-            if (data[i] == '\r' && i + 1 < len &&
-                data[i+1] == '\n')
-                i += 2;
-            else
-                i++;
-            if (keepends)
-                eol = i;
-        }
-        SPLIT_APPEND(data, j, eol);
-        j = i;
-    }
-    if (j < len) {
-        SPLIT_APPEND(data, j, len);
-    }
-
-    Py_DECREF(string);
-    return list;
-
-  onError:
-    Py_XDECREF(list);
     Py_DECREF(string);
-    return NULL;
-}
-
-static
-PyObject *split_char(PyUnicodeObject *self,
-                     PyObject *list,
-                     Py_UNICODE ch,
-                     Py_ssize_t maxcount)
-{
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len = self->length;
-    PyObject *str;
-    register const Py_UNICODE *buf = self->str;
-
-    for (i = j = 0; i < len; ) {
-        if (buf[i] == ch) {
-            if (maxcount-- <= 0)
-                break;
-            SPLIT_APPEND(buf, j, i);
-            i = j = i + 1;
-        } else
-            i++;
-    }
-    if (j <= len) {
-        SPLIT_APPEND(buf, j, len);
-    }
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
-}
-
-static
-PyObject *split_substring(PyUnicodeObject *self,
-                          PyObject *list,
-                          PyUnicodeObject *substring,
-                          Py_ssize_t maxcount)
-{
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len = self->length;
-    Py_ssize_t sublen = substring->length;
-    PyObject *str;
-
-    for (i = j = 0; i <= len - sublen; ) {
-        if (Py_UNICODE_MATCH(self, i, substring)) {
-            if (maxcount-- <= 0)
-                break;
-            SPLIT_APPEND(self->str, j, i);
-            i = j = i + sublen;
-        } else
-            i++;
-    }
-    if (j <= len) {
-        SPLIT_APPEND(self->str, j, len);
-    }
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
-}
-
-static
-PyObject *rsplit_whitespace(PyUnicodeObject *self,
-                            PyObject *list,
-                            Py_ssize_t maxcount)
-{
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len = self->length;
-    PyObject *str;
-    register const Py_UNICODE *buf = self->str;
-
-    for (i = j = len - 1; i >= 0; ) {
-        /* find a token */
-        while (i >= 0 && Py_UNICODE_ISSPACE(buf[i]))
-            i--;
-        j = i;
-        while (i >= 0 && !Py_UNICODE_ISSPACE(buf[i]))
-            i--;
-        if (j > i) {
-            if (maxcount-- <= 0)
-                break;
-            SPLIT_APPEND(buf, i + 1, j + 1);
-            while (i >= 0 && Py_UNICODE_ISSPACE(buf[i]))
-                i--;
-            j = i;
-        }
-    }
-    if (j >= 0) {
-        SPLIT_APPEND(buf, 0, j + 1);
-    }
-    if (PyList_Reverse(list) < 0)
-        goto onError;
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
-}
-
-static
-PyObject *rsplit_char(PyUnicodeObject *self,
-                      PyObject *list,
-                      Py_UNICODE ch,
-                      Py_ssize_t maxcount)
-{
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len = self->length;
-    PyObject *str;
-    register const Py_UNICODE *buf = self->str;
-
-    for (i = j = len - 1; i >= 0; ) {
-        if (buf[i] == ch) {
-            if (maxcount-- <= 0)
-                break;
-            SPLIT_APPEND(buf, i + 1, j + 1);
-            j = i = i - 1;
-        } else
-            i--;
-    }
-    if (j >= -1) {
-        SPLIT_APPEND(buf, 0, j + 1);
-    }
-    if (PyList_Reverse(list) < 0)
-        goto onError;
     return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
 }
 
 static
-PyObject *rsplit_substring(PyUnicodeObject *self,
-                           PyObject *list,
-                           PyUnicodeObject *substring,
-                           Py_ssize_t maxcount)
-{
-    register Py_ssize_t i;
-    register Py_ssize_t j;
-    Py_ssize_t len = self->length;
-    Py_ssize_t sublen = substring->length;
-    PyObject *str;
-
-    for (i = len - sublen, j = len; i >= 0; ) {
-        if (Py_UNICODE_MATCH(self, i, substring)) {
-            if (maxcount-- <= 0)
-                break;
-            SPLIT_APPEND(self->str, i + sublen, j);
-            j = i;
-            i -= sublen;
-        } else
-            i--;
-    }
-    if (j >= 0) {
-        SPLIT_APPEND(self->str, 0, j);
-    }
-    if (PyList_Reverse(list) < 0)
-        goto onError;
-    return list;
-
-  onError:
-    Py_DECREF(list);
-    return NULL;
-}
-
-#undef SPLIT_APPEND
-
-static
 PyObject *split(PyUnicodeObject *self,
                 PyUnicodeObject *substring,
                 Py_ssize_t maxcount)
 {
-    PyObject *list;
-
     if (maxcount < 0)
         maxcount = PY_SSIZE_T_MAX;
 
-    list = PyList_New(0);
-    if (!list)
-        return NULL;
-
     if (substring == NULL)
-        return split_whitespace(self,list,maxcount);
-
-    else if (substring->length == 1)
-        return split_char(self,list,substring->str[0],maxcount);
+        return stringlib_split_whitespace(
+            (PyObject*) self,  self->str, self->length, maxcount
+            );
 
-    else if (substring->length == 0) {
-        Py_DECREF(list);
-        PyErr_SetString(PyExc_ValueError, "empty separator");
-        return NULL;
-    }
-    else
-        return split_substring(self,list,substring,maxcount);
+    return stringlib_split(
+        (PyObject*) self,  self->str, self->length,
+        substring->str, substring->length,
+        maxcount
+        );
 }
 
 static
@@ -6027,28 +5762,19 @@ PyObject *rsplit(PyUnicodeObject *self,
                  PyUnicodeObject *substring,
                  Py_ssize_t maxcount)
 {
-    PyObject *list;
-
     if (maxcount < 0)
         maxcount = PY_SSIZE_T_MAX;
 
-    list = PyList_New(0);
-    if (!list)
-        return NULL;
-
     if (substring == NULL)
-        return rsplit_whitespace(self,list,maxcount);
-
-    else if (substring->length == 1)
-        return rsplit_char(self,list,substring->str[0],maxcount);
+        return stringlib_rsplit_whitespace(
+            (PyObject*) self,  self->str, self->length, maxcount
+            );
 
-    else if (substring->length == 0) {
-        Py_DECREF(list);
-        PyErr_SetString(PyExc_ValueError, "empty separator");
-        return NULL;
-    }
-    else
-        return rsplit_substring(self,list,substring,maxcount);
+    return stringlib_rsplit(
+        (PyObject*) self,  self->str, self->length,
+        substring->str, substring->length,
+        maxcount
+        );
 }
 
 static
@@ -6061,9 +5787,13 @@ PyObject *replace(PyUnicodeObject *self,
 
     if (maxcount < 0)
         maxcount = PY_SSIZE_T_MAX;
+    else if (maxcount == 0 || self->length == 0)
+        goto nothing;
 
     if (str1->length == str2->length) {
         /* same length */
+        if (str1->length == 0)
+            goto nothing;
         Py_ssize_t i;
         if (str1->length == 1) {
             /* replace characters */
@@ -6083,8 +5813,8 @@ PyObject *replace(PyUnicodeObject *self,
                     u->str[i] = u2;
                 }
         } else {
-            i = fastsearch(
-                self->str, self->length, str1->str, str1->length, FAST_SEARCH
+            i = stringlib_find(
+                self->str, self->length, str1->str, str1->length, 0
                 );
             if (i < 0)
                 goto nothing;
@@ -6092,14 +5822,20 @@ PyObject *replace(PyUnicodeObject *self,
             if (!u)
                 return NULL;
             Py_UNICODE_COPY(u->str, self->str, self->length);
-            while (i <= self->length - str1->length)
-                if (Py_UNICODE_MATCH(self, i, str1)) {
-                    if (--maxcount < 0)
-                        break;
-                    Py_UNICODE_COPY(u->str+i, str2->str, str2->length);
-                    i += str1->length;
-                } else
-                    i++;
+
+            /* change everything in-place, starting with this one */
+            Py_UNICODE_COPY(u->str+i, str2->str, str2->length);
+            i += str1->length;
+
+            while ( --maxcount > 0) {
+                i = stringlib_find(self->str+i, self->length-i,
+                                   str1->str, str1->length,
+                                   i);
+                if (i == -1)
+                    break;
+                Py_UNICODE_COPY(u->str+i, str2->str, str2->length);
+                i += str1->length;
+            }
         }
     } else {
 
@@ -6108,9 +5844,8 @@ PyObject *replace(PyUnicodeObject *self,
         Py_UNICODE *p;
 
         /* replace strings */
-        n = stringlib_count(self->str, self->length, str1->str, str1->length);
-        if (n > maxcount)
-            n = maxcount;
+        n = stringlib_count(self->str, self->length, str1->str, str1->length,
+                            maxcount);
         if (n == 0)
             goto nothing;
         /* new_size = self->length + n * (str2->length - str1->length)); */
@@ -6140,15 +5875,12 @@ PyObject *replace(PyUnicodeObject *self,
         if (str1->length > 0) {
             while (n-- > 0) {
                 /* look for next match */
-                j = i;
-                while (j <= e) {
-                    if (Py_UNICODE_MATCH(self, j, str1))
-                        break;
-                    j++;
-                }
-                if (j > i) {
-                    if (j > e)
-                        break;
+                j = stringlib_find(self->str+i, self->length-i,
+                                   str1->str, str1->length,
+                                   i);
+                if (j == -1)
+                    break;
+                else if (j > i) {
                     /* copy unchanged part [i:j] */
                     Py_UNICODE_COPY(p, self->str+i, j-i);
                     p += j - i;
@@ -6585,11 +6317,11 @@ unicode_count(PyUnicodeObject *self, PyObject *args)
     if (substring == NULL)
         return NULL;
 
-    FIX_START_END(self);
-
+    ADJUST_INDICES(start, end, self->length);
     result = PyInt_FromSsize_t(
         stringlib_count(self->str + start, end - start,
-                        substring->str, substring->length)
+                        substring->str, substring->length,
+                        PY_SSIZE_T_MAX)
         );
 
     Py_DECREF(substring);
@@ -9132,11 +8864,3 @@ _PyUnicode_Fini(void)
 #ifdef __cplusplus
 }
 #endif
-
-
-/*
-  Local variables:
-  c-basic-offset: 4
-  indent-tabs-mode: nil
-  End:
-*/
diff --git a/PC/VS8.0/pythoncore.vcproj b/PC/VS8.0/pythoncore.vcproj
index ad48cee..31c7992 100644
--- a/PC/VS8.0/pythoncore.vcproj
+++ b/PC/VS8.0/pythoncore.vcproj
@@ -1539,6 +1539,10 @@
 				>
 			</File>
 			<File
+				RelativePath="..\..\Objects\stringlib\split.h"
+				>
+			</File>
+			<File
 				RelativePath="..\..\Objects\structseq.c"
 				>
 			</File>
diff --git a/PCbuild/pythoncore.vcproj b/PCbuild/pythoncore.vcproj
index 47521f01..6078c86 100644
--- a/PCbuild/pythoncore.vcproj
+++ b/PCbuild/pythoncore.vcproj
@@ -1539,6 +1539,10 @@
 				>
 			</File>
 			<File
+				RelativePath="..\Objects\stringlib\split.h"
+				>
+			</File>
+			<File
 				RelativePath="..\Objects\structseq.c"
 				>
 			</File>