Use CPython's implementation of str_rsplit

The organization is kind of hacky since we have to copy str_rsplit
into stringobject.c so it can be use stringlib, but we want to reference
it from str.cpp.

from_cpython/Objects/stringobject.c

@@ -3,11 +3,17 @@
 #include "Python.h"
 
 #include "stringlib/stringdefs.h"
-#include "stringlib/string_format.h"
+#include "stringlib/fastsearch.h"
+
+#include "stringlib/count.h"
+#include "stringlib/find.h"
+#include "stringlib/split.h"
 
 #define _Py_InsertThousandsGrouping _PyString_InsertThousandsGrouping
 #include "stringlib/localeutil.h"
 
+#include "stringlib/string_format.h"
+
 // do_string_format needs to be declared as a static function, since it's used by both stringobject.c
 // and unicodeobject.c.  We want to access it from str.cpp, though, so just use this little forwarding
 // function.
@@ -16,3 +22,30 @@
 PyObject * _do_string_format(PyObject *self, PyObject *args, PyObject *kwargs) {
     return do_string_format(self, args, kwargs);
 }
+
+PyObject* string_rsplit(PyStringObject* self, PyObject* args) {
+    Py_ssize_t len = PyString_GET_SIZE(self), n;
+    Py_ssize_t maxsplit = -1;
+    const char* s = PyString_AS_STRING(self), *sub;
+    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 stringlib_rsplit_whitespace((PyObject*)self, s, len, maxsplit);
+    if (PyString_Check(subobj)) {
+        sub = PyString_AS_STRING(subobj);
+        n = PyString_GET_SIZE(subobj);
+    }
+#ifdef Py_USING_UNICODE
+    else if (PyUnicode_Check(subobj))
+        return PyUnicode_RSplit((PyObject*)self, subobj, maxsplit);
+#endif
+    else if (PyObject_AsCharBuffer(subobj, &sub, &n))
+        return NULL;
+
+    return stringlib_rsplit((PyObject*)self, s, len, sub, n, maxsplit);
+}
+

src/runtime/list.cpp

@@ -39,10 +39,6 @@ extern "C" int PyList_Append(PyObject* op, PyObject* newitem) noexcept {
     return 0;
 }
 
-extern "C" int PyList_Reverse(PyObject* v) noexcept {
-    Py_FatalError("unimplemented");
-}
-
 extern "C" PyObject** PyList_Items(PyObject* op) noexcept {
     RELEASE_ASSERT(PyList_Check(op), "");
 
@@ -469,6 +465,21 @@ Box* listReverse(BoxedList* self) {
     return None;
 }
 
+extern "C" int PyList_Reverse(PyObject* v) noexcept {
+    if (v == NULL || !PyList_Check(v)) {
+        PyErr_BadInternalCall();
+        return -1;
+    }
+
+    try {
+        listReverse(static_cast<BoxedList*>(v));
+    } catch (ExcInfo e) {
+        setCAPIException(e);
+        return -1;
+    }
+    return 0;
+}
+
 void listSort(BoxedList* self, Box* cmp, Box* key, Box* reverse) {
     LOCK_REGION(self->lock.asWrite());
     assert(self->cls == list_cls);

src/runtime/str.cpp

@@ -23,6 +23,7 @@
 
 #include "Python.h"
 
+#include "capi/types.h"
 #include "core/common.h"
 #include "core/types.h"
 #include "core/util.h"
@@ -33,6 +34,8 @@
 #include "runtime/types.h"
 #include "runtime/util.h"
 
+extern "C" PyObject* string_rsplit(PyStringObject* self, PyObject* args) noexcept;
+
 namespace pyston {
 
 BoxedString::BoxedString(const char* s, size_t n) : s(s, n) {
@@ -1636,14 +1639,6 @@ Box* strSplit(BoxedString* self, BoxedString* sep, BoxedInt* _max_split) {
     }
 }
 
-Box* strRsplit(BoxedString* self, BoxedString* sep, BoxedInt* _max_split) {
-    // TODO: implement this for real
-    // for now, just forward rsplit() to split() in the cases they have to return the same value
-    assert(isSubclass(_max_split->cls, int_cls));
-    RELEASE_ASSERT(_max_split->n <= 0, "");
-    return strSplit(self, sep, _max_split);
-}
-
 Box* strStrip(BoxedString* self, Box* chars) {
     assert(self->cls == str_cls);
 
@@ -2236,6 +2231,10 @@ void strDestructor(Box* b) {
     self->s.~basic_string();
 }
 
+static PyMethodDef string_methods[] = {
+    { "rsplit", (PyCFunction)string_rsplit, METH_VARARGS, NULL },
+};
+
 void setupStr() {
     str_cls->simple_destructor = strDestructor;
     str_cls->tp_flags |= Py_TPFLAGS_HAVE_NEWBUFFER;
@@ -2329,8 +2328,10 @@ void setupStr() {
 
     str_cls->giveAttr(
         "split", new BoxedFunction(boxRTFunction((void*)strSplit, LIST, 3, 2, false, false), { None, boxInt(-1) }));
-    str_cls->giveAttr(
-        "rsplit", new BoxedFunction(boxRTFunction((void*)strRsplit, LIST, 3, 2, false, false), { None, boxInt(-1) }));
+
+    for (auto& md : string_methods) {
+        str_cls->giveAttr(md.ml_name, new BoxedMethodDescriptor(&md, str_cls));
+    }
 
     CLFunction* count = boxRTFunction((void*)strCount2Unboxed, INT, 2);
     addRTFunction(count, (void*)strCount2, BOXED_INT);

test/tests/str_functions.py

@@ -15,6 +15,8 @@ print "  test  ".rsplit()
 print "  test  ".rsplit(' ')
 print "  test  ".rsplit(None)
 print "1<>2<>3".rsplit('<>')
+print "1<>2<>3".rsplit('<>', 1)
+print "1<>2<>3".split('<>', 1)
 
 print map(bool, ["hello", "", "world"])