Add rsplit method for str and unicode builtin types.
SF feature request #801847.
Original patch is written by Sean Reifschneider.
diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex
index 7feda60..4ce6ec5 100644
--- a/Doc/lib/libstdtypes.tex
+++ b/Doc/lib/libstdtypes.tex
@@ -694,6 +694,24 @@
\versionchanged[Support for the \var{fillchar} argument]{2.4}
\end{methoddesc}
+\begin{methoddesc}[string]{rsplit}{\optional{, sep\optional{, maxsplit}}}
+Return a list of the words of the string, scanning the string from
+the end working forward. The resulting list of words is in the
+same order as \function{split()}. If the optional second argument
+\var{sep} is absent or \code{None}, the words are separated by
+arbitrary strings of whitespace characters (space, tab, newline,
+return, formfeed). If the second argument \var{sep} is present and
+not \code{None}, it specifies a string to be used as the word
+separator. The returned list will then have one more item than the
+number of non-overlapping occurrences of the separator in the string.
+The optional third argument \var{maxsplit} defaults to 0. If it
+is nonzero, at most \var{maxsplit} number of splits occur, and the
+remainder of the string is returned as the first element of the
+list (thus, the list will have at most \code{\var{maxsplit}+1}
+elements).
+\versionadded{2.4}
+\end{methoddesc}
+
\begin{methoddesc}[string]{rstrip}{\optional{chars}}
Return a copy of the string with trailing characters removed. If
\var{chars} is omitted or \code{None}, whitespace characters are
diff --git a/Doc/lib/libstring.tex b/Doc/lib/libstring.tex
index 3f902cf..11054e2 100644
--- a/Doc/lib/libstring.tex
+++ b/Doc/lib/libstring.tex
@@ -215,6 +215,23 @@
elements).
\end{funcdesc}
+\begin{funcdesc}{rsplit}{s\optional{, sep\optional{, maxsplit}}}
+ Return a list of the words of the string \var{s}, scanning \var{s} from
+ the end working forward. The resulting list of words is in the same
+ order as \function{split()}. If the optional second argument \var{sep}
+ is absent or \code{None}, the words are separated by arbitrary strings
+ of whitespace characters (space, tab, newline, return, formfeed).
+ If the second argument \var{sep} is present and not \code{None}, it
+ specifies a string to be used as the word separator. The returned
+ list will then have one more item than the number of non-overlapping
+ occurrences of the separator in the string. The optional third argument
+ \var{maxsplit} defaults to 0. If it is nonzero, at most \var{maxsplit}
+ number of splits occur, and the remainder of the string is returned
+ as the first element of the list (thus, the list will have at most
+ \code{\var{maxsplit}+1} elements).
+ \versionadded{2.4}
+\end{funcdesc}
+
\begin{funcdesc}{splitfields}{s\optional{, sep\optional{, maxsplit}}}
This function behaves identically to \function{split()}. (In the
past, \function{split()} was only used with one argument, while
diff --git a/Include/unicodeobject.h b/Include/unicodeobject.h
index 24e59de..1690f8a 100644
--- a/Include/unicodeobject.h
+++ b/Include/unicodeobject.h
@@ -185,6 +185,7 @@
# define PyUnicode_Resize PyUnicodeUCS2_Resize
# define PyUnicode_SetDefaultEncoding PyUnicodeUCS2_SetDefaultEncoding
# define PyUnicode_Split PyUnicodeUCS2_Split
+# define PyUnicode_RSplit PyUnicodeUCS2_RSplit
# define PyUnicode_Splitlines PyUnicodeUCS2_Splitlines
# define PyUnicode_Tailmatch PyUnicodeUCS2_Tailmatch
# define PyUnicode_Translate PyUnicodeUCS2_Translate
@@ -959,6 +960,25 @@
int keepends /* If true, line end markers are included */
);
+/* Split a string giving a list of Unicode strings.
+
+ If sep is NULL, splitting will be done at all whitespace
+ substrings. Otherwise, splits occur at the given separator.
+
+ At most maxsplit splits will be done. But unlike PyUnicode_Split
+ PyUnicode_RSplit splits from the end of the string. If negative,
+ no limit is set.
+
+ Separators are not included in the resulting list.
+
+*/
+
+PyAPI_FUNC(PyObject*) PyUnicode_RSplit(
+ PyObject *s, /* String to split */
+ PyObject *sep, /* String separator */
+ int maxsplit /* Maxsplit count */
+ );
+
/* Translate a string by applying a character mapping table to it and
return the resulting Unicode object.
diff --git a/Lib/string.py b/Lib/string.py
index 0a77f46..bc10c20 100644
--- a/Lib/string.py
+++ b/Lib/string.py
@@ -121,6 +121,18 @@
return s.split(sep, maxsplit)
splitfields = split
+# Split a string into a list of space/tab-separated words
+def rsplit(s, sep=None, maxsplit=-1):
+ """rsplit(s [,sep [,maxsplit]]) -> list of strings
+
+ Return a list of the words in the string s, using sep as the
+ delimiter string, starting at the end of the string and working
+ to the front. If maxsplit is given, at most maxsplit splits are
+ done. If sep is not specified or is None, any whitespace string
+ is a separator.
+ """
+ return s.rsplit(sep, maxsplit)
+
# Join fields with optional separator
def join(words, sep = ' '):
"""join(list [,sep]) -> string
diff --git a/Lib/test/string_tests.py b/Lib/test/string_tests.py
index 236c577..c3e53ad 100644
--- a/Lib/test/string_tests.py
+++ b/Lib/test/string_tests.py
@@ -189,6 +189,26 @@
self.checkraises(TypeError, 'hello', 'split', 42, 42, 42)
+ def test_rsplit(self):
+ self.checkequal(['this', 'is', 'the', 'rsplit', 'function'],
+ 'this is the rsplit function', 'rsplit')
+ self.checkequal(['a', 'b', 'c', 'd'], 'a|b|c|d', 'rsplit', '|')
+ self.checkequal(['a|b', 'c', 'd'], 'a|b|c|d', 'rsplit', '|', 2)
+ self.checkequal(['a b c', 'd'], 'a b c d', 'rsplit', None, 1)
+ self.checkequal(['a b', 'c', 'd'], 'a b c d', 'rsplit', None, 2)
+ self.checkequal(['a', 'b', 'c', 'd'], 'a b c d', 'rsplit', None, 3)
+ self.checkequal(['a', 'b', 'c', 'd'], 'a b c d', 'rsplit', None, 4)
+ self.checkequal(['a b c d'], 'a b c d', 'rsplit', None, 0)
+ self.checkequal(['a, b, c', 'd'], 'a, b, c, d', 'rsplit', ', ', 1)
+ self.checkequal(['a, b', 'c', 'd'], 'a, b, c, d', 'rsplit', ', ', 2)
+ self.checkequal(['a', 'b', 'c', 'd'], 'a, b, c, d', 'rsplit', ', ', 3)
+ self.checkequal(['a', 'b', 'c', 'd'], 'a, b, c, d', 'rsplit', ', ', 4)
+ self.checkequal(['a, b, c, d'], 'a, b, c, d', 'rsplit', ', ', 0)
+ self.checkequal(['a b', 'c', 'd'], 'a b c d', 'rsplit', None, 2)
+ self.checkequal(['a\x00b', 'c'], 'a\x00b\x00c', 'rsplit', '\x00', 1)
+ self.checkequal(['', ''], 'abcd', 'rsplit', 'abcd')
+ self.checkequal([u'a b', u'c', u'd'], 'a b c d', 'rsplit', u' ', 2)
+
def test_strip(self):
self.checkequal('hello', ' hello ', 'strip')
self.checkequal('hello ', ' hello ', 'lstrip')
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
index d3351df..9512059 100644
--- a/Objects/stringobject.c
+++ b/Objects/stringobject.c
@@ -1407,6 +1407,129 @@
return NULL;
}
+static PyObject *
+rsplit_whitespace(const char *s, int len, int maxsplit)
+{
+ int i, j, err;
+ PyObject* item;
+ PyObject *list = PyList_New(0);
+
+ if (list == NULL)
+ return NULL;
+
+ for (i = j = len - 1; i >= 0; ) {
+ while (i >= 0 && isspace(Py_CHARMASK(s[i])))
+ i--;
+ j = i;
+ while (i >= 0 && !isspace(Py_CHARMASK(s[i])))
+ i--;
+ if (j > i) {
+ if (maxsplit-- <= 0)
+ break;
+ item = PyString_FromStringAndSize(s+i+1, (int)(j-i));
+ if (item == NULL)
+ goto finally;
+ err = PyList_Insert(list, 0, item);
+ Py_DECREF(item);
+ if (err < 0)
+ goto finally;
+ while (i >= 0 && isspace(Py_CHARMASK(s[i])))
+ i--;
+ j = i;
+ }
+ }
+ if (j >= 0) {
+ item = PyString_FromStringAndSize(s, (int)(j + 1));
+ if (item == NULL)
+ goto finally;
+ err = PyList_Insert(list, 0, item);
+ Py_DECREF(item);
+ if (err < 0)
+ goto finally;
+ }
+ return list;
+ finally:
+ Py_DECREF(list);
+ return NULL;
+}
+
+
+PyDoc_STRVAR(rsplit__doc__,
+"S.rsplit([sep [,maxsplit]]) -> list of strings\n\
+\n\
+Return a list of the words in the string S, using sep as the\n\
+delimiter string, starting at the end of the string and working\n\
+to the front. If maxsplit is given, at most maxsplit splits are\n\
+done. If sep is not specified or is None, any whitespace string\n\
+is a separator.");
+
+static PyObject *
+string_rsplit(PyStringObject *self, PyObject *args)
+{
+ int len = PyString_GET_SIZE(self), n, i, j, err;
+ int maxsplit = -1;
+ const char *s = PyString_AS_STRING(self), *sub;
+ PyObject *list, *item, *subobj = Py_None;
+
+ if (!PyArg_ParseTuple(args, "|Oi:rsplit", &subobj, &maxsplit))
+ return NULL;
+ if (maxsplit < 0)
+ maxsplit = INT_MAX;
+ if (subobj == Py_None)
+ return rsplit_whitespace(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;
+ if (n == 0) {
+ PyErr_SetString(PyExc_ValueError, "empty separator");
+ return NULL;
+ }
+
+ list = PyList_New(0);
+ if (list == NULL)
+ return NULL;
+
+ j = len;
+ i = j - n;
+ while (i >= 0) {
+ if (s[i] == sub[0] && memcmp(s+i, sub, n) == 0) {
+ if (maxsplit-- <= 0)
+ break;
+ item = PyString_FromStringAndSize(s+i+n, (int)(j-i-n));
+ if (item == NULL)
+ goto fail;
+ err = PyList_Insert(list, 0, item);
+ Py_DECREF(item);
+ if (err < 0)
+ goto fail;
+ j = i;
+ i -= n;
+ }
+ else
+ i--;
+ }
+ item = PyString_FromStringAndSize(s, j);
+ if (item == NULL)
+ goto fail;
+ err = PyList_Insert(list, 0, item);
+ Py_DECREF(item);
+ if (err < 0)
+ goto fail;
+
+ return list;
+
+ fail:
+ Py_DECREF(list);
+ return NULL;
+}
+
PyDoc_STRVAR(join__doc__,
"S.join(sequence) -> string\n\
@@ -3064,6 +3187,7 @@
string.maketrans(). */
{"join", (PyCFunction)string_join, METH_O, join__doc__},
{"split", (PyCFunction)string_split, METH_VARARGS, split__doc__},
+ {"rsplit", (PyCFunction)string_rsplit, METH_VARARGS, rsplit__doc__},
{"lower", (PyCFunction)string_lower, METH_NOARGS, lower__doc__},
{"upper", (PyCFunction)string_upper, METH_NOARGS, upper__doc__},
{"islower", (PyCFunction)string_islower, METH_NOARGS, islower__doc__},
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
index f87d749..19d0353 100644
--- a/Objects/unicodeobject.c
+++ b/Objects/unicodeobject.c
@@ -4053,7 +4053,7 @@
}
#define SPLIT_APPEND(data, left, right) \
- str = PyUnicode_FromUnicode(data + left, right - left); \
+ str = PyUnicode_FromUnicode((data) + (left), (right) - (left)); \
if (!str) \
goto onError; \
if (PyList_Append(list, str)) { \
@@ -4063,6 +4063,17 @@
else \
Py_DECREF(str);
+#define SPLIT_INSERT(data, left, right) \
+ str = PyUnicode_FromUnicode((data) + (left), (right) - (left)); \
+ if (!str) \
+ goto onError; \
+ if (PyList_Insert(list, 0, str)) { \
+ Py_DECREF(str); \
+ goto onError; \
+ } \
+ else \
+ Py_DECREF(str);
+
static
PyObject *split_whitespace(PyUnicodeObject *self,
PyObject *list,
@@ -4214,7 +4225,106 @@
return NULL;
}
+static
+PyObject *rsplit_whitespace(PyUnicodeObject *self,
+ PyObject *list,
+ int maxcount)
+{
+ register int i;
+ register int j;
+ int len = self->length;
+ PyObject *str;
+
+ for (i = j = len - 1; i >= 0; ) {
+ /* find a token */
+ while (i >= 0 && Py_UNICODE_ISSPACE(self->str[i]))
+ i--;
+ j = i;
+ while (i >= 0 && !Py_UNICODE_ISSPACE(self->str[i]))
+ i--;
+ if (j > i) {
+ if (maxcount-- <= 0)
+ break;
+ SPLIT_INSERT(self->str, i + 1, j + 1);
+ while (i >= 0 && Py_UNICODE_ISSPACE(self->str[i]))
+ i--;
+ j = i;
+ }
+ }
+ if (j >= 0) {
+ SPLIT_INSERT(self->str, 0, j + 1);
+ }
+ return list;
+
+ onError:
+ Py_DECREF(list);
+ return NULL;
+}
+
+static
+PyObject *rsplit_char(PyUnicodeObject *self,
+ PyObject *list,
+ Py_UNICODE ch,
+ int maxcount)
+{
+ register int i;
+ register int j;
+ int len = self->length;
+ PyObject *str;
+
+ for (i = j = len - 1; i >= 0; ) {
+ if (self->str[i] == ch) {
+ if (maxcount-- <= 0)
+ break;
+ SPLIT_INSERT(self->str, i + 1, j + 1);
+ j = i = i - 1;
+ } else
+ i--;
+ }
+ if (j >= 0) {
+ SPLIT_INSERT(self->str, 0, j + 1);
+ }
+ return list;
+
+ onError:
+ Py_DECREF(list);
+ return NULL;
+}
+
+static
+PyObject *rsplit_substring(PyUnicodeObject *self,
+ PyObject *list,
+ PyUnicodeObject *substring,
+ int maxcount)
+{
+ register int i;
+ register int j;
+ int len = self->length;
+ int 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_INSERT(self->str, i + sublen, j);
+ j = i;
+ i -= sublen;
+ } else
+ i--;
+ }
+ if (j >= 0) {
+ SPLIT_INSERT(self->str, 0, j);
+ }
+ return list;
+
+ onError:
+ Py_DECREF(list);
+ return NULL;
+}
+
#undef SPLIT_APPEND
+#undef SPLIT_INSERT
static
PyObject *split(PyUnicodeObject *self,
@@ -4246,6 +4356,35 @@
}
static
+PyObject *rsplit(PyUnicodeObject *self,
+ PyUnicodeObject *substring,
+ int maxcount)
+{
+ PyObject *list;
+
+ if (maxcount < 0)
+ maxcount = INT_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);
+
+ else if (substring->length == 0) {
+ Py_DECREF(list);
+ PyErr_SetString(PyExc_ValueError, "empty separator");
+ return NULL;
+ }
+ else
+ return rsplit_substring(self,list,substring,maxcount);
+}
+
+static
PyObject *replace(PyUnicodeObject *self,
PyUnicodeObject *str1,
PyUnicodeObject *str2,
@@ -5675,6 +5814,56 @@
return PyUnicode_Split((PyObject *)self, substring, maxcount);
}
+PyObject *PyUnicode_RSplit(PyObject *s,
+ PyObject *sep,
+ int maxsplit)
+{
+ PyObject *result;
+
+ s = PyUnicode_FromObject(s);
+ if (s == NULL)
+ return NULL;
+ if (sep != NULL) {
+ sep = PyUnicode_FromObject(sep);
+ if (sep == NULL) {
+ Py_DECREF(s);
+ return NULL;
+ }
+ }
+
+ result = rsplit((PyUnicodeObject *)s, (PyUnicodeObject *)sep, maxsplit);
+
+ Py_DECREF(s);
+ Py_XDECREF(sep);
+ return result;
+}
+
+PyDoc_STRVAR(rsplit__doc__,
+"S.rsplit([sep [,maxsplit]]) -> list of strings\n\
+\n\
+Return a list of the words in S, using sep as the\n\
+delimiter string, starting at the end of the string and\n\
+working to the front. If maxsplit is given, at most maxsplit\n\
+splits are done. If sep is not specified, any whitespace string\n\
+is a separator.");
+
+static PyObject*
+unicode_rsplit(PyUnicodeObject *self, PyObject *args)
+{
+ PyObject *substring = Py_None;
+ int maxcount = -1;
+
+ if (!PyArg_ParseTuple(args, "|Oi:rsplit", &substring, &maxcount))
+ return NULL;
+
+ if (substring == Py_None)
+ return rsplit(self, NULL, maxcount);
+ else if (PyUnicode_Check(substring))
+ return rsplit(self, (PyUnicodeObject *)substring, maxcount);
+ else
+ return PyUnicode_RSplit((PyObject *)self, substring, maxcount);
+}
+
PyDoc_STRVAR(splitlines__doc__,
"S.splitlines([keepends]]) -> list of strings\n\
\n\
@@ -5870,6 +6059,7 @@
{"encode", (PyCFunction) unicode_encode, METH_VARARGS, encode__doc__},
{"replace", (PyCFunction) unicode_replace, METH_VARARGS, replace__doc__},
{"split", (PyCFunction) unicode_split, METH_VARARGS, split__doc__},
+ {"rsplit", (PyCFunction) unicode_rsplit, METH_VARARGS, rsplit__doc__},
{"join", (PyCFunction) unicode_join, METH_O, join__doc__},
{"capitalize", (PyCFunction) unicode_capitalize, METH_NOARGS, capitalize__doc__},
{"title", (PyCFunction) unicode_title, METH_NOARGS, title__doc__},