]> granicus.if.org Git - python/commitdiff
Somewhat-preliminary slice-object and extended slicing support for ctypes.
authorThomas Wouters <thomas@python.org>
Thu, 30 Aug 2007 21:01:17 +0000 (21:01 +0000)
committerThomas Wouters <thomas@python.org>
Thu, 30 Aug 2007 21:01:17 +0000 (21:01 +0000)
The exact behaviour of omitted and negative indices for the Pointer type may
need a closer look (especially as it's subtly different from simple slices)
but there's time yet before 2.6, and not enough before 3.0a1 :-)

Lib/ctypes/test/test_arrays.py
Lib/ctypes/test/test_buffers.py
Lib/ctypes/test/test_cast.py
Lib/ctypes/test/test_memfunctions.py
Lib/ctypes/test/test_slicing.py
Lib/ctypes/test/test_strings.py
Lib/ctypes/test/test_structures.py
Lib/ctypes/test/test_unicode.py
Modules/_ctypes/_ctypes.c

index c812ff627d11a88189285ab9a51ad3e972b2243b..a68ef614978972f9f559dfbcd5baaa3dd58e140c 100644 (file)
@@ -95,6 +95,10 @@ class ArrayTestCase(unittest.TestCase):
         p = create_string_buffer("foo")
         sz = (c_char * 3).from_address(addressof(p))
         self.failUnlessEqual(sz[:], "foo")
+        self.failUnlessEqual(sz[::], "foo")
+        self.failUnlessEqual(sz[::-1], "oof")
+        self.failUnlessEqual(sz[::3], "f")
+        self.failUnlessEqual(sz[1:4:2], "o")
         self.failUnlessEqual(sz.value, "foo")
 
     try:
@@ -106,6 +110,10 @@ class ArrayTestCase(unittest.TestCase):
             p = create_unicode_buffer("foo")
             sz = (c_wchar * 3).from_address(addressof(p))
             self.failUnlessEqual(sz[:], "foo")
+            self.failUnlessEqual(sz[::], "foo")
+            self.failUnlessEqual(sz[::-1], "oof")
+            self.failUnlessEqual(sz[::3], "f")
+            self.failUnlessEqual(sz[1:4:2], "o")
             self.failUnlessEqual(sz.value, "foo")
 
 if __name__ == '__main__':
index 07527a6dc5d27d5e31a113a4f9f30e2789964e50..5b96d127a3e5623f279e1a407d09fe828c895368 100644 (file)
@@ -15,6 +15,10 @@ class StringBufferTestCase(unittest.TestCase):
         self.failUnless(type(b[0]) is str)
         self.failUnlessEqual(b[0], "a")
         self.failUnlessEqual(b[:], "abc\0")
+        self.failUnlessEqual(b[::], "abc\0")
+        self.failUnlessEqual(b[::-1], "\0cba")
+        self.failUnlessEqual(b[::2], "ac")
+        self.failUnlessEqual(b[::5], "a")
 
     def test_string_conversion(self):
         b = create_string_buffer(u"abc")
@@ -23,6 +27,10 @@ class StringBufferTestCase(unittest.TestCase):
         self.failUnless(type(b[0]) is str)
         self.failUnlessEqual(b[0], "a")
         self.failUnlessEqual(b[:], "abc\0")
+        self.failUnlessEqual(b[::], "abc\0")
+        self.failUnlessEqual(b[::-1], "\0cba")
+        self.failUnlessEqual(b[::2], "ac")
+        self.failUnlessEqual(b[::5], "a")
 
     try:
         c_wchar
@@ -41,6 +49,10 @@ class StringBufferTestCase(unittest.TestCase):
             self.failUnless(type(b[0]) is unicode)
             self.failUnlessEqual(b[0], u"a")
             self.failUnlessEqual(b[:], "abc\0")
+            self.failUnlessEqual(b[::], "abc\0")
+            self.failUnlessEqual(b[::-1], "\0cba")
+            self.failUnlessEqual(b[::2], "ac")
+            self.failUnlessEqual(b[::5], "a")
 
         def test_unicode_conversion(self):
             b = create_unicode_buffer("abc")
@@ -49,6 +61,10 @@ class StringBufferTestCase(unittest.TestCase):
             self.failUnless(type(b[0]) is unicode)
             self.failUnlessEqual(b[0], u"a")
             self.failUnlessEqual(b[:], "abc\0")
+            self.failUnlessEqual(b[::], "abc\0")
+            self.failUnlessEqual(b[::-1], "\0cba")
+            self.failUnlessEqual(b[::2], "ac")
+            self.failUnlessEqual(b[::5], "a")
 
 if __name__ == "__main__":
     unittest.main()
index 7371b0fe24b78a0837e418bbd52b057271812d62..22c647528a87ccb97131b55afedbec87b3221cd2 100644 (file)
@@ -50,12 +50,24 @@ class Test(unittest.TestCase):
     def test_other(self):
         p = cast((c_int * 4)(1, 2, 3, 4), POINTER(c_int))
         self.failUnlessEqual(p[:4], [1,2, 3, 4])
+        self.failUnlessEqual(p[:4:], [1, 2, 3, 4])
+        self.failUnlessEqual(p[3:-1:-1], [4, 3, 2, 1])
+        self.failUnlessEqual(p[:4:3], [1, 4])
         c_int()
         self.failUnlessEqual(p[:4], [1, 2, 3, 4])
+        self.failUnlessEqual(p[:4:], [1, 2, 3, 4])
+        self.failUnlessEqual(p[3:-1:-1], [4, 3, 2, 1])
+        self.failUnlessEqual(p[:4:3], [1, 4])
         p[2] = 96
         self.failUnlessEqual(p[:4], [1, 2, 96, 4])
+        self.failUnlessEqual(p[:4:], [1, 2, 96, 4])
+        self.failUnlessEqual(p[3:-1:-1], [4, 96, 2, 1])
+        self.failUnlessEqual(p[:4:3], [1, 4])
         c_int()
         self.failUnlessEqual(p[:4], [1, 2, 96, 4])
+        self.failUnlessEqual(p[:4:], [1, 2, 96, 4])
+        self.failUnlessEqual(p[3:-1:-1], [4, 96, 2, 1])
+        self.failUnlessEqual(p[:4:3], [1, 4])
 
     def test_char_p(self):
         # This didn't work: bad argument to internal function
index aef7a739fcf9a0fb54355c081ea1c5612540b393..390c8ef71e25ee864447f3dec9f466e867257eb7 100644 (file)
@@ -30,6 +30,14 @@ class MemFunctionsTest(unittest.TestCase):
         self.failUnlessEqual(cast(a, c_char_p).value, "abcdef")
         self.failUnlessEqual(cast(a, POINTER(c_byte))[:7],
                              [97, 98, 99, 100, 101, 102, 0])
+        self.failUnlessEqual(cast(a, POINTER(c_byte))[:7:],
+                             [97, 98, 99, 100, 101, 102, 0])
+        self.failUnlessEqual(cast(a, POINTER(c_byte))[6:-1:-1],
+                             [0, 102, 101, 100, 99, 98, 97])
+        self.failUnlessEqual(cast(a, POINTER(c_byte))[:7:2],
+                             [97, 99, 101, 0])
+        self.failUnlessEqual(cast(a, POINTER(c_byte))[:7:7],
+                             [97])
 
     def test_string_at(self):
         s = string_at("foo bar")
index 511c3d34a50ff090254604bacc4503f7960775d6..25bd801a6a6ff59dccf8ab09eca4736cf057d8d2 100644 (file)
@@ -8,13 +8,22 @@ class SlicesTestCase(unittest.TestCase):
         a = (c_int * 100)(*xrange(1100, 1200))
         b = range(1100, 1200)
         self.failUnlessEqual(a[0:2], b[0:2])
+        self.failUnlessEqual(a[0:2:], b[0:2:])
         self.failUnlessEqual(len(a), len(b))
         self.failUnlessEqual(a[5:7], b[5:7])
+        self.failUnlessEqual(a[5:7:], b[5:7:])
         self.failUnlessEqual(a[-1], b[-1])
         self.failUnlessEqual(a[:], b[:])
+        self.failUnlessEqual(a[::], b[::])
+        self.failUnlessEqual(a[10::-1], b[10::-1])
+        self.failUnlessEqual(a[30:20:-1], b[30:20:-1])
+        self.failUnlessEqual(a[:12:6], b[:12:6])
+        self.failUnlessEqual(a[2:6:4], b[2:6:4])
 
         a[0:5] = range(5, 10)
         self.failUnlessEqual(a[0:5], range(5, 10))
+        self.failUnlessEqual(a[0:5:], range(5, 10))
+        self.failUnlessEqual(a[4::-1], range(9, 4, -1))
 
     def test_setslice_cint(self):
         a = (c_int * 100)(*xrange(1100, 1200))
@@ -22,17 +31,36 @@ class SlicesTestCase(unittest.TestCase):
 
         a[32:47] = range(32, 47)
         self.failUnlessEqual(a[32:47], range(32, 47))
-
-        from operator import setslice
+        a[32:47] = range(132, 147)
+        self.failUnlessEqual(a[32:47:], range(132, 147))
+        a[46:31:-1] = range(232, 247)
+        self.failUnlessEqual(a[32:47:1], range(246, 231, -1))
+
+        a[32:47] = range(1132, 1147)
+        self.failUnlessEqual(a[:], b)
+        a[32:47:7] = range(3)
+        b[32:47:7] = range(3)
+        self.failUnlessEqual(a[:], b)
+        a[33::-3] = range(12)
+        b[33::-3] = range(12)
+        self.failUnlessEqual(a[:], b)
+
+        from operator import setslice, setitem
 
         # TypeError: int expected instead of str instance
         self.assertRaises(TypeError, setslice, a, 0, 5, "abcde")
+        self.assertRaises(TypeError, setitem, a, slice(0, 5), "abcde")
         # TypeError: int expected instead of str instance
         self.assertRaises(TypeError, setslice, a, 0, 5, ["a", "b", "c", "d", "e"])
+        self.assertRaises(TypeError, setitem, a, slice(0, 5),
+                          ["a", "b", "c", "d", "e"])
         # TypeError: int expected instead of float instance
         self.assertRaises(TypeError, setslice, a, 0, 5, [1, 2, 3, 4, 3.14])
+        self.assertRaises(TypeError, setitem, a, slice(0, 5),
+                          [1, 2, 3, 4, 3.14])
         # ValueError: Can only assign sequence of same size
         self.assertRaises(ValueError, setslice, a, 0, 5, range(32))
+        self.assertRaises(ValueError, setitem, a, slice(0, 5), range(32))
 
     def test_char_ptr(self):
         s = "abcdefghijklmnopqrstuvwxyz"
@@ -42,15 +70,32 @@ class SlicesTestCase(unittest.TestCase):
         dll.my_free.restype = None
         res = dll.my_strdup(s)
         self.failUnlessEqual(res[:len(s)], s)
+        self.failUnlessEqual(res[:3], s[:3])
+        self.failUnlessEqual(res[:len(s):], s)
+        self.failUnlessEqual(res[len(s)-1:-1:-1], s[::-1])
+        self.failUnlessEqual(res[len(s)-1:5:-7], s[:5:-7])
+        self.failUnlessEqual(res[0:-1:-1], s[0::-1])
 
         import operator
+        self.assertRaises(ValueError, operator.getitem,
+                          res, slice(None, None, None))
+        self.assertRaises(ValueError, operator.getitem,
+                          res, slice(0, None, None))
+        self.assertRaises(ValueError, operator.getitem,
+                          res, slice(None, 5, -1))
+        self.assertRaises(ValueError, operator.getitem,
+                          res, slice(-5, None, None))
+
         self.assertRaises(TypeError, operator.setslice,
                           res, 0, 5, u"abcde")
+        self.assertRaises(TypeError, operator.setitem,
+                          res, slice(0, 5), u"abcde")
         dll.my_free(res)
 
         dll.my_strdup.restype = POINTER(c_byte)
         res = dll.my_strdup(s)
         self.failUnlessEqual(res[:len(s)], range(ord("a"), ord("z")+1))
+        self.failUnlessEqual(res[:len(s):], range(ord("a"), ord("z")+1))
         dll.my_free(res)
 
     def test_char_ptr_with_free(self):
@@ -80,6 +125,10 @@ class SlicesTestCase(unittest.TestCase):
 
         p = (c_char * 27)(*s)
         self.failUnlessEqual(p[:], s)
+        self.failUnlessEqual(p[::], s)
+        self.failUnlessEqual(p[::-1], s[::-1])
+        self.failUnlessEqual(p[5::-2], s[5::-2])
+        self.failUnlessEqual(p[2:5:-3], s[2:5:-3])
 
 
     try:
@@ -96,10 +145,15 @@ class SlicesTestCase(unittest.TestCase):
             dll.my_free.restype = None
             res = dll.my_wcsdup(s)
             self.failUnlessEqual(res[:len(s)], s)
+            self.failUnlessEqual(res[:len(s):], s)
+            self.failUnlessEqual(res[len(s)-1:-1:-1], s[::-1])
+            self.failUnlessEqual(res[len(s)-1:5:-7], s[:5:-7])
 
             import operator
             self.assertRaises(TypeError, operator.setslice,
                               res, 0, 5, u"abcde")
+            self.assertRaises(TypeError, operator.setitem,
+                              res, slice(0, 5), u"abcde")
             dll.my_free(res)
 
             if sizeof(c_wchar) == sizeof(c_short):
@@ -111,7 +165,11 @@ class SlicesTestCase(unittest.TestCase):
             else:
                 return
             res = dll.my_wcsdup(s)
-            self.failUnlessEqual(res[:len(s)-1], range(ord("a"), ord("z")+1))
+            tmpl = range(ord("a"), ord("z")+1)
+            self.failUnlessEqual(res[:len(s)-1], tmpl)
+            self.failUnlessEqual(res[:len(s)-1:], tmpl)
+            self.failUnlessEqual(res[len(s)-2:-1:-1], tmpl[::-1])
+            self.failUnlessEqual(res[len(s)-2:5:-7], tmpl[:5:-7])
             dll.my_free(res)
 
 ################################################################
index b5072290c8c480d1a7e4e1f71dbb90f143ea0b12..72248e14b9748ec7e0abd06628d9596dfc0dc504 100644 (file)
@@ -121,6 +121,9 @@ class StringTestCase(unittest.TestCase):
     def XX_test_initialized_strings(self):
 
         self.failUnless(c_string("ab", 4).raw[:2] == "ab")
+        self.failUnless(c_string("ab", 4).raw[:2:] == "ab")
+        self.failUnless(c_string("ab", 4).raw[:2:-1] == "ba")
+        self.failUnless(c_string("ab", 4).raw[:2:2] == "a")
         self.failUnless(c_string("ab", 4).raw[-1] == "\000")
         self.failUnless(c_string("ab", 2).raw == "a\000")
 
index 613163d0ccae00fec2e8d290c631e7927216eb69..f9a11096938d58cc0cc9e20df7436bbe636dd33a 100644 (file)
@@ -236,7 +236,13 @@ class StructureTestCase(unittest.TestCase):
 
         # can use tuple to initialize array (but not list!)
         self.failUnlessEqual(SomeInts((1, 2)).a[:], [1, 2, 0, 0])
+        self.failUnlessEqual(SomeInts((1, 2)).a[::], [1, 2, 0, 0])
+        self.failUnlessEqual(SomeInts((1, 2)).a[::-1], [0, 0, 2, 1])
+        self.failUnlessEqual(SomeInts((1, 2)).a[::2], [1, 0])
+        self.failUnlessEqual(SomeInts((1, 2)).a[1:5:6], [2])
+        self.failUnlessEqual(SomeInts((1, 2)).a[6:4:-1], [])
         self.failUnlessEqual(SomeInts((1, 2, 3, 4)).a[:], [1, 2, 3, 4])
+        self.failUnlessEqual(SomeInts((1, 2, 3, 4)).a[::], [1, 2, 3, 4])
         # too long
         # XXX Should raise ValueError?, not RuntimeError
         self.assertRaises(RuntimeError, SomeInts, (1, 2, 3, 4, 5))
index 78c5cf87c86caeb20f8833eb31904bd10088cc87..88d077394f36da39a7f7a122995d805e3cf69563 100644 (file)
@@ -59,11 +59,19 @@ else:
             ctypes.set_conversion_mode("ascii", "replace")
             buf = ctypes.create_unicode_buffer("abäöü")
             self.failUnlessEqual(buf[:], u"ab\uFFFD\uFFFD\uFFFD\0")
+            self.failUnlessEqual(buf[::], u"ab\uFFFD\uFFFD\uFFFD\0")
+            self.failUnlessEqual(buf[::-1], u"\0\uFFFD\uFFFD\uFFFDba")
+            self.failUnlessEqual(buf[::2], u"a\uFFFD\uFFFD")
+            self.failUnlessEqual(buf[6:5:-1], u"")
 
             ctypes.set_conversion_mode("ascii", "ignore")
             buf = ctypes.create_unicode_buffer("abäöü")
             # is that correct? not sure.  But with 'ignore', you get what you pay for..
             self.failUnlessEqual(buf[:], u"ab\0\0\0\0")
+            self.failUnlessEqual(buf[::], u"ab\0\0\0\0")
+            self.failUnlessEqual(buf[::-1], u"\0\0\0\0ba")
+            self.failUnlessEqual(buf[::2], u"a\0\0")
+            self.failUnlessEqual(buf[6:5:-1], u"")
 
     import _ctypes_test
     func = ctypes.CDLL(_ctypes_test.__file__)._testfunc_p_p
@@ -105,11 +113,17 @@ else:
             ctypes.set_conversion_mode("ascii", "replace")
             buf = ctypes.create_string_buffer(u"abäöü")
             self.failUnlessEqual(buf[:], "ab???\0")
+            self.failUnlessEqual(buf[::], "ab???\0")
+            self.failUnlessEqual(buf[::-1], "\0???ba")
+            self.failUnlessEqual(buf[::2], "a??")
+            self.failUnlessEqual(buf[6:5:-1], "")
 
             ctypes.set_conversion_mode("ascii", "ignore")
             buf = ctypes.create_string_buffer(u"abäöü")
             # is that correct? not sure.  But with 'ignore', you get what you pay for..
             self.failUnlessEqual(buf[:], "ab\0\0\0\0")
+            self.failUnlessEqual(buf[::], "ab\0\0\0\0")
+            self.failUnlessEqual(buf[::-1], "\0\0\0\0ba")
 
 if __name__ == '__main__':
     unittest.main()
index 020f4734a3bf00d6f42c0ba80aa7d5ec2cac828c..4c7c8968c7058e2378c6ca366603182c1aafeb02 100644 (file)
@@ -3768,6 +3768,108 @@ Array_slice(PyObject *_self, Py_ssize_t ilow, Py_ssize_t ihigh)
        return (PyObject *)np;
 }
 
+static PyObject *
+Array_subscript(PyObject *_self, PyObject *item)
+{
+       CDataObject *self = (CDataObject *)_self;
+
+       if (PyIndex_Check(item)) {
+               Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
+               
+               if (i == -1 && PyErr_Occurred())
+                       return NULL;
+               if (i < 0)
+                       i += self->b_length;
+               return Array_item(_self, i);
+       }
+       else if PySlice_Check(item) {
+               StgDictObject *stgdict, *itemdict;
+               PyObject *proto;
+               PyObject *np;
+               Py_ssize_t start, stop, step, slicelen, cur, i;
+               
+               if (PySlice_GetIndicesEx((PySliceObject *)item,
+                                        self->b_length, &start, &stop,
+                                        &step, &slicelen) < 0) {
+                       return NULL;
+               }
+               
+               stgdict = PyObject_stgdict((PyObject *)self);
+               assert(stgdict); /* Cannot be NULL for array object instances */
+               proto = stgdict->proto;
+               itemdict = PyType_stgdict(proto);
+               assert(itemdict); /* proto is the item type of the array, a
+                                    ctypes type, so this cannot be NULL */
+
+               if (itemdict->getfunc == getentry("c")->getfunc) {
+                       char *ptr = (char *)self->b_ptr;
+                       char *dest;
+
+                       if (slicelen <= 0)
+                               return PyString_FromString("");
+                       if (step == 1) {
+                               return PyString_FromStringAndSize(ptr + start,
+                                                                 slicelen);
+                       }
+                       dest = (char *)PyMem_Malloc(slicelen);
+
+                       if (dest == NULL)
+                               return PyErr_NoMemory();
+
+                       for (cur = start, i = 0; i < slicelen;
+                            cur += step, i++) {
+                               dest[i] = ptr[cur];
+                       }
+
+                       np = PyString_FromStringAndSize(dest, slicelen);
+                       PyMem_Free(dest);
+                       return np;
+               }
+#ifdef CTYPES_UNICODE
+               if (itemdict->getfunc == getentry("u")->getfunc) {
+                       wchar_t *ptr = (wchar_t *)self->b_ptr;
+                       wchar_t *dest;
+                       
+                       if (slicelen <= 0)
+                               return PyUnicode_FromUnicode(NULL, 0);
+                       if (step == 1) {
+                               return PyUnicode_FromWideChar(ptr + start,
+                                                             slicelen);
+                       }
+
+                       dest = (wchar_t *)PyMem_Malloc(
+                                               slicelen * sizeof(wchar_t));
+                       
+                       for (cur = start, i = 0; i < slicelen;
+                            cur += step, i++) {
+                               dest[i] = ptr[cur];
+                       }
+                       
+                       np = PyUnicode_FromWideChar(dest, slicelen);
+                       PyMem_Free(dest);
+                       return np;
+               }
+#endif
+
+               np = PyList_New(slicelen);
+               if (np == NULL)
+                       return NULL;
+
+               for (cur = start, i = 0; i < slicelen;
+                    cur += step, i++) {
+                       PyObject *v = Array_item(_self, cur);
+                       PyList_SET_ITEM(np, i, v);
+               }
+               return np;
+       }
+       else {
+               PyErr_SetString(PyExc_TypeError, 
+                               "indices must be integers");
+               return NULL;
+       }
+
+}
+
 static int
 Array_ass_item(PyObject *_self, Py_ssize_t index, PyObject *value)
 {
@@ -3839,6 +3941,63 @@ Array_ass_slice(PyObject *_self, Py_ssize_t ilow, Py_ssize_t ihigh, PyObject *va
        return 0;
 }
 
+static int
+Array_ass_subscript(PyObject *_self, PyObject *item, PyObject *value)
+{
+       CDataObject *self = (CDataObject *)_self;
+       
+       if (value == NULL) {
+               PyErr_SetString(PyExc_TypeError,
+                               "Array does not support item deletion");
+               return -1;
+       }
+
+       if (PyIndex_Check(item)) {
+               Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
+               
+               if (i == -1 && PyErr_Occurred())
+                       return -1;
+               if (i < 0)
+                       i += self->b_length;
+               return Array_ass_item(_self, i, value);
+       }
+       else if (PySlice_Check(item)) {
+               Py_ssize_t start, stop, step, slicelen, otherlen, i, cur;
+               
+               if (PySlice_GetIndicesEx((PySliceObject *)item,
+                                        self->b_length, &start, &stop,
+                                        &step, &slicelen) < 0) {
+                       return -1;
+               }
+               if ((step < 0 && start < stop) ||
+                   (step > 0 && start > stop))
+                       stop = start;
+
+               otherlen = PySequence_Length(value);
+               if (otherlen != slicelen) {
+                       PyErr_SetString(PyExc_ValueError,
+                               "Can only assign sequence of same size");
+                       return -1;
+               }
+               for (cur = start, i = 0; i < otherlen; cur += step, i++) {
+                       PyObject *item = PySequence_GetItem(value, i);
+                       int result;
+                       if (item == NULL)
+                               return -1;
+                       result = Array_ass_item(_self, cur, item);
+                       Py_DECREF(item);
+                       if (result == -1)
+                               return -1;
+               }
+               return 0;
+       }
+       else {
+               PyErr_SetString(PyExc_TypeError,
+                               "indices must be integer");
+               return -1;
+       }
+}
+
 static Py_ssize_t
 Array_length(PyObject *_self)
 {
@@ -3860,6 +4019,12 @@ static PySequenceMethods Array_as_sequence = {
        0,                                      /* sq_inplace_repeat; */
 };
 
+static PyMappingMethods Array_as_mapping = {
+       Array_length,
+       Array_subscript,
+       Array_ass_subscript,
+};
+
 PyTypeObject Array_Type = {
        PyVarObject_HEAD_INIT(NULL, 0)
        "_ctypes.Array",
@@ -3873,7 +4038,7 @@ PyTypeObject Array_Type = {
        0,                                      /* tp_repr */
        0,                                      /* tp_as_number */
        &Array_as_sequence,                     /* tp_as_sequence */
-       0,                                      /* tp_as_mapping */
+       &Array_as_mapping,                      /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */
        0,                                      /* tp_str */
@@ -4359,6 +4524,139 @@ Pointer_slice(PyObject *_self, Py_ssize_t ilow, Py_ssize_t ihigh)
        return (PyObject *)np;
 }
 
+static PyObject *
+Pointer_subscript(PyObject *_self, PyObject *item)
+{
+       CDataObject *self = (CDataObject *)_self;
+       if (PyIndex_Check(item)) {
+               Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
+               if (i == -1 && PyErr_Occurred())
+                       return NULL;
+               return Pointer_item(_self, i);
+       }
+       else if (PySlice_Check(item)) {
+               PySliceObject *slice = (PySliceObject *)item;
+               Py_ssize_t start, stop, step;
+               PyObject *np;
+               StgDictObject *stgdict, *itemdict;
+               PyObject *proto;
+               Py_ssize_t i, len, cur;
+
+               /* Since pointers have no length, and we want to apply
+                  different semantics to negative indices than normal
+                  slicing, we have to dissect the slice object ourselves.*/
+               if (slice->step == Py_None) {
+                       step = 1;
+               }
+               else {
+                       step = PyNumber_AsSsize_t(slice->step,
+                                                 PyExc_ValueError);
+                       if (step == -1 && PyErr_Occurred())
+                               return NULL;
+                       if (step == 0) {
+                               PyErr_SetString(PyExc_ValueError,
+                                               "slice step cannot be zero");
+                               return NULL;
+                       }
+               }
+               if (slice->start == Py_None) {
+                       if (step < 0) {
+                               PyErr_SetString(PyExc_ValueError,
+                                               "slice start is required "
+                                               "for step < 0");
+                               return NULL;
+                       }
+                       start = 0;
+               }
+               else {
+                       start = PyNumber_AsSsize_t(slice->start,
+                                                  PyExc_ValueError);
+                       if (start == -1 && PyErr_Occurred())
+                               return NULL;
+               }
+               if (slice->stop == Py_None) {
+                       PyErr_SetString(PyExc_ValueError,
+                                       "slice stop is required");
+                       return NULL;
+               }
+               stop = PyNumber_AsSsize_t(slice->stop,
+                                         PyExc_ValueError);
+               if (stop == -1 && PyErr_Occurred())
+                       return NULL;
+               if ((step > 0 && start > stop) ||
+                   (step < 0 && start < stop))
+                       len = 0;
+               else if (step > 0)
+                       len = (stop - start - 1) / step + 1;
+               else
+                       len = (stop - start + 1) / step + 1;
+
+               stgdict = PyObject_stgdict((PyObject *)self);
+               assert(stgdict); /* Cannot be NULL for pointer instances */
+               proto = stgdict->proto;
+               assert(proto);
+               itemdict = PyType_stgdict(proto);
+               assert(itemdict);
+               if (itemdict->getfunc == getentry("c")->getfunc) {
+                       char *ptr = *(char **)self->b_ptr;
+                       char *dest;
+                       
+                       if (len <= 0)
+                               return PyString_FromString("");
+                       if (step == 1) {
+                               return PyString_FromStringAndSize(ptr + start,
+                                                                 len);
+                       }
+                       dest = (char *)PyMem_Malloc(len);
+                       if (dest == NULL)
+                               return PyErr_NoMemory();
+                       for (cur = start, i = 0; i < len; cur += step, i++) {
+                               dest[i] = ptr[cur];
+                       }
+                       np = PyString_FromStringAndSize(dest, len);
+                       PyMem_Free(dest);
+                       return np;
+               }
+#ifdef CTYPES_UNICODE
+               if (itemdict->getfunc == getentry("u")->getfunc) {
+                       wchar_t *ptr = *(wchar_t **)self->b_ptr;
+                       wchar_t *dest;
+                       
+                       if (len <= 0)
+                               return PyUnicode_FromUnicode(NULL, 0);
+                       if (step == 1) {
+                               return PyUnicode_FromWideChar(ptr + start,
+                                                             len);
+                       }
+                       dest = (wchar_t *)PyMem_Malloc(len * sizeof(wchar_t));
+                       if (dest == NULL)
+                               return PyErr_NoMemory();
+                       for (cur = start, i = 0; i < len; cur += step, i++) {
+                               dest[i] = ptr[cur];
+                       }
+                       np = PyUnicode_FromWideChar(dest, len);
+                       PyMem_Free(dest);
+                       return np;
+               }
+#endif
+
+               np = PyList_New(len);
+               if (np == NULL)
+                       return NULL;
+
+               for (cur = start, i = 0; i < len; cur += step, i++) {
+                       PyObject *v = Pointer_item(_self, cur);
+                       PyList_SET_ITEM(np, i, v);
+               }
+               return np;
+       }
+       else {
+               PyErr_SetString(PyExc_TypeError,
+                               "Pointer indices must be integer");
+               return NULL;
+       }
+}
+
 static PySequenceMethods Pointer_as_sequence = {
        0,                                      /* inquiry sq_length; */
        0,                                      /* binaryfunc sq_concat; */
@@ -4373,6 +4671,11 @@ static PySequenceMethods Pointer_as_sequence = {
        0,                                      /* intargfunc sq_inplace_repeat; */
 };
 
+static PyMappingMethods Pointer_as_mapping = {
+       0,
+       Pointer_subscript,
+};
+
 static int
 Pointer_nonzero(CDataObject *self)
 {
@@ -4406,7 +4709,7 @@ PyTypeObject Pointer_Type = {
        0,                                      /* tp_repr */
        &Pointer_as_number,                     /* tp_as_number */
        &Pointer_as_sequence,                   /* tp_as_sequence */
-       0,                                      /* tp_as_mapping */
+       &Pointer_as_mapping,                    /* tp_as_mapping */
        0,                                      /* tp_hash */
        0,                                      /* tp_call */
        0,                                      /* tp_str */