Code by Inyeol Lee, submitted to SF bug 595350, to implement
the string/unicode method .replace() with a zero-lengt first argument.
Inyeol contributed tests for this too.
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index 9f41317..0b79a06 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -2215,11 +2215,11 @@
char *new_s;
int nfound, offset, new_len;
- if (len == 0 || pat_len > len)
+ if (len == 0 || (pat_len == 0 && sub_len == 0) || pat_len > len)
goto return_same;
/* find length of output string */
- nfound = mymemcnt(str, len, pat, pat_len);
+ nfound = (pat_len > 0) ? mymemcnt(str, len, pat, pat_len) : len + 1;
if (count < 0)
count = INT_MAX;
else if (nfound > count)
@@ -2242,25 +2242,38 @@
return NULL;
out_s = new_s;
- for (; count > 0 && len > 0; --count) {
- /* find index of next instance of pattern */
- offset = mymemfind(str, len, pat, pat_len);
- if (offset == -1)
- break;
+ if (pat_len > 0) {
+ for (; nfound > 0; --nfound) {
+ /* find index of next instance of pattern */
+ offset = mymemfind(str, len, pat, pat_len);
+ if (offset == -1)
+ break;
- /* copy non matching part of input string */
- memcpy(new_s, str, offset);
- str += offset + pat_len;
- len -= offset + pat_len;
+ /* copy non matching part of input string */
+ memcpy(new_s, str, offset);
+ str += offset + pat_len;
+ len -= offset + pat_len;
- /* copy substitute into the output string */
- new_s += offset;
- memcpy(new_s, sub, sub_len);
- new_s += sub_len;
+ /* copy substitute into the output string */
+ new_s += offset;
+ memcpy(new_s, sub, sub_len);
+ new_s += sub_len;
+ }
+ /* copy any remaining values into output string */
+ if (len > 0)
+ memcpy(new_s, str, len);
}
- /* copy any remaining values into output string */
- if (len > 0)
- memcpy(new_s, str, len);
+ else {
+ for (;;++str, --len) {
+ memcpy(new_s, sub, sub_len);
+ new_s += sub_len;
+ if (--nfound <= 0) {
+ memcpy(new_s, str, len);
+ break;
+ }
+ *new_s++ = *str;
+ }
+ }
}
*out_len = new_len;
return out_s;
@@ -2317,10 +2330,6 @@
else if (PyObject_AsCharBuffer(replobj, &repl, &repl_len))
return NULL;
- if (sub_len <= 0) {
- PyErr_SetString(PyExc_ValueError, "empty pattern string");
- return NULL;
- }
new_s = mymemreplace(str,len,sub,sub_len,repl,repl_len,count,&out_len);
if (new_s == NULL) {
PyErr_NoMemory();