Partially implement SF feature request 444708.

Add optional arg to string methods strip(), lstrip(), rstrip().
The optional arg specifies characters to delete.

Also for UserString.

Still to do:

- Misc/NEWS
- LaTeX docs (I did the docstrings though)
- Unicode methods, and Unicode support in the string methods.

Lib/UserString.py

@@ -108,7 +108,7 @@ class UserString:
     def join(self, seq): return self.data.join(seq)
     def ljust(self, width): return self.__class__(self.data.ljust(width))
     def lower(self): return self.__class__(self.data.lower())
-    def lstrip(self): return self.__class__(self.data.lstrip())
+    def lstrip(self, sep=None): return self.__class__(self.data.lstrip(sep))
     def replace(self, old, new, maxsplit=-1):
         return self.__class__(self.data.replace(old, new, maxsplit))
     def rfind(self, sub, start=0, end=sys.maxint):
@@ -116,13 +116,13 @@ class UserString:
     def rindex(self, sub, start=0, end=sys.maxint):
         return self.data.rindex(sub, start, end)
     def rjust(self, width): return self.__class__(self.data.rjust(width))
-    def rstrip(self): return self.__class__(self.data.rstrip())
+    def rstrip(self, sep=None): return self.__class__(self.data.rstrip(sep))
     def split(self, sep=None, maxsplit=-1):
         return self.data.split(sep, maxsplit)
     def splitlines(self, keepends=0): return self.data.splitlines(keepends)
     def startswith(self, prefix, start=0, end=sys.maxint):
         return self.data.startswith(prefix, start, end)
-    def strip(self): return self.__class__(self.data.strip())
+    def strip(self, sep=None): return self.__class__(self.data.strip(sep))
     def swapcase(self): return self.__class__(self.data.swapcase())
     def title(self): return self.__class__(self.data.title())
     def translate(self, *args):

Lib/test/string_tests.py

@@ -163,6 +163,18 @@ def run_method_tests(test):
     test('rstrip', '   hello   ', '   hello')
     test('strip', 'hello', 'hello')
 
+    # strip/lstrip/rstrip with None arg
+    test('strip', '   hello   ', 'hello', None)
+    test('lstrip', '   hello   ', 'hello   ', None)
+    test('rstrip', '   hello   ', '   hello', None)
+    test('strip', 'hello', 'hello', None)
+
+    # strip/lstrip/rstrip with real arg
+    test('strip', 'xyzzyhelloxyzzy', 'hello', 'xyz')
+    test('lstrip', 'xyzzyhelloxyzzy', 'helloxyzzy', 'xyz')
+    test('rstrip', 'xyzzyhelloxyzzy', 'xyzzyhello', 'xyz')
+    test('strip', 'hello', 'hello', 'xyz')
+
     test('swapcase', 'HeLLo cOmpUteRs', 'hEllO CoMPuTErS')
     test('translate', 'xyzabcdef', 'xyzxyz', transtable, 'def')
 

Objects/stringobject.c

@@ -1002,6 +1002,9 @@ static PyBufferProcs string_as_buffer = {
 #define RIGHTSTRIP 1
 #define BOTHSTRIP 2
 
+/* Arrays indexed by above */
+static const char *stripname[] = {"lstrip", "rstrip", "strip"};
+
 
 static PyObject *
 split_whitespace(const char *s, int len, int maxsplit)
@@ -1376,6 +1379,39 @@ string_rindex(PyStringObject *self, PyObject *args)
 }
 
 
+static PyObject *
+do_xstrip(PyStringObject *self, int striptype, PyObject *sepobj)
+{
+	char *s = PyString_AS_STRING(self);
+	int len = PyString_GET_SIZE(self);
+	char *sep = PyString_AS_STRING(sepobj);
+	int seplen = PyString_GET_SIZE(sepobj);
+	int i, j;
+
+	i = 0;
+	if (striptype != RIGHTSTRIP) {
+		while (i < len && memchr(sep, Py_CHARMASK(s[i]), seplen)) {
+			i++;
+		}
+	}
+
+	j = len;
+	if (striptype != LEFTSTRIP) {
+		do {
+			j--;
+		} while (j >= i && memchr(sep, Py_CHARMASK(s[j]), seplen));
+		j++;
+	}
+
+	if (i == 0 && j == len && PyString_CheckExact(self)) {
+		Py_INCREF(self);
+		return (PyObject*)self;
+	}
+	else
+		return PyString_FromStringAndSize(s+i, j-i);
+}
+
+
 static PyObject *
 do_strip(PyStringObject *self, int striptype)
 {
@@ -1406,40 +1442,75 @@ do_strip(PyStringObject *self, int striptype)
 }
 
 
+static PyObject *
+do_argstrip(PyStringObject *self, int striptype, PyObject *args)
+{
+	PyObject *sep = NULL;
+
+	if (!PyArg_ParseTuple(args, "|O:[lr]strip", &sep))
+		return NULL;
+
+	if (sep != NULL && sep != Py_None) {
+		/* XXX What about Unicode? */
+		if (!PyString_Check(sep)) {
+			PyErr_Format(PyExc_TypeError,
+				     "%s arg must be None or string",
+				     stripname[striptype]);
+			return NULL;
+		}
+		return do_xstrip(self, striptype, sep);
+	}
+
+	return do_strip(self, striptype);
+}
+
+
 static char strip__doc__[] =
-"S.strip() -> string\n\
+"S.strip([sep]) -> string\n\
 \n\
 Return a copy of the string S with leading and trailing\n\
-whitespace removed.";
+whitespace removed.\n\
+If sep is given and not None, remove characters in sep instead.";
 
 static PyObject *
-string_strip(PyStringObject *self)
+string_strip(PyStringObject *self, PyObject *args)
 {
-	return do_strip(self, BOTHSTRIP);
+	if (PyTuple_GET_SIZE(args) == 0)
+		return do_strip(self, BOTHSTRIP); /* Common case */
+	else
+		return do_argstrip(self, BOTHSTRIP, args);
 }
 
 
 static char lstrip__doc__[] =
-"S.lstrip() -> string\n\
+"S.lstrip([sep]) -> string\n\
 \n\
-Return a copy of the string S with leading whitespace removed.";
+Return a copy of the string S with leading whitespace removed.\n\
+If sep is given and not None, remove characters in sep instead.";
 
 static PyObject *
-string_lstrip(PyStringObject *self)
+string_lstrip(PyStringObject *self, PyObject *args)
 {
-	return do_strip(self, LEFTSTRIP);
+	if (PyTuple_GET_SIZE(args) == 0)
+		return do_strip(self, LEFTSTRIP); /* Common case */
+	else
+		return do_argstrip(self, LEFTSTRIP, args);
 }
 
 
 static char rstrip__doc__[] =
-"S.rstrip() -> string\n\
+"S.rstrip([sep]) -> string\n\
 \n\
-Return a copy of the string S with trailing whitespace removed.";
+Return a copy of the string S with trailing whitespace removed.\n\
+If sep is given and not None, remove characters in sep instead.";
 
 static PyObject *
-string_rstrip(PyStringObject *self)
+string_rstrip(PyStringObject *self, PyObject *args)
 {
-	return do_strip(self, RIGHTSTRIP);
+	if (PyTuple_GET_SIZE(args) == 0)
+		return do_strip(self, RIGHTSTRIP); /* Common case */
+	else
+		return do_argstrip(self, RIGHTSTRIP, args);
 }
 
 
@@ -2644,13 +2715,13 @@ string_methods[] = {
 	{"endswith",   (PyCFunction)string_endswith,    METH_VARARGS, endswith__doc__},
 	{"find",       (PyCFunction)string_find,        METH_VARARGS, find__doc__},
 	{"index",      (PyCFunction)string_index,       METH_VARARGS, index__doc__},
-	{"lstrip",     (PyCFunction)string_lstrip,      METH_NOARGS, lstrip__doc__},
+	{"lstrip",     (PyCFunction)string_lstrip,      METH_VARARGS, lstrip__doc__},
 	{"replace",     (PyCFunction)string_replace,    METH_VARARGS, replace__doc__},
 	{"rfind",       (PyCFunction)string_rfind,      METH_VARARGS, rfind__doc__},
 	{"rindex",      (PyCFunction)string_rindex,     METH_VARARGS, rindex__doc__},
-	{"rstrip",      (PyCFunction)string_rstrip,     METH_NOARGS, rstrip__doc__},
+	{"rstrip",      (PyCFunction)string_rstrip,     METH_VARARGS, rstrip__doc__},
 	{"startswith",  (PyCFunction)string_startswith, METH_VARARGS, startswith__doc__},
-	{"strip",       (PyCFunction)string_strip,      METH_NOARGS, strip__doc__},
+	{"strip",       (PyCFunction)string_strip,      METH_VARARGS, strip__doc__},
 	{"swapcase",    (PyCFunction)string_swapcase,   METH_NOARGS, swapcase__doc__},
 	{"translate",   (PyCFunction)string_translate,  METH_VARARGS, translate__doc__},
 	{"title",       (PyCFunction)string_title,      METH_NOARGS, title__doc__},