Fix the bug described in

http://mail.python.org/pipermail/python-dev/2002-June/025461.html

with test cases.

Also includes extended slice support for arrays, which I thought I'd
already checked in but obviously not.

Lib/test/test_array.py

@@ -3,7 +3,8 @@
    Roger E. Masse
 """
 import array
-from test_support import verbose, TESTFN, unlink, TestFailed, have_unicode
+from test_support import verbose, TESTFN, unlink, TestFailed,\
+     have_unicode, vereq
 
 def main():
     testtype('c', 'c')
@@ -312,6 +313,46 @@ def testtype(type, example):
         a.reverse()
         if a != array.array(type, [4, 3, 1]):
             raise TestFailed, "array(%s) reverse-test" % `type`
+        # extended slicing
+        # subscription
+        a = array.array(type, [0,1,2,3,4])
+        vereq(a[::], a)
+        vereq(a[::2], array.array(type, [0,2,4]))
+        vereq(a[1::2], array.array(type, [1,3]))
+        vereq(a[::-1], array.array(type, [4,3,2,1,0]))
+        vereq(a[::-2], array.array(type, [4,2,0]))
+        vereq(a[3::-2], array.array(type, [3,1]))
+        vereq(a[-100:100:], a)
+        vereq(a[100:-100:-1], a[::-1])
+        vereq(a[-100L:100L:2L], array.array(type, [0,2,4]))
+        vereq(a[1000:2000:2], array.array(type, []))
+        vereq(a[-1000:-2000:-2], array.array(type, []))
+        #  deletion
+        del a[::2]
+        vereq(a, array.array(type, [1,3]))
+        a = array.array(type, range(5))
+        del a[1::2]
+        vereq(a, array.array(type, [0,2,4]))
+        a = array.array(type, range(5))
+        del a[1::-2]
+        vereq(a, array.array(type, [0,2,3,4]))
+        #  assignment
+        a = array.array(type, range(10))
+        a[::2] = array.array(type, [-1]*5)
+        vereq(a, array.array(type, [-1, 1, -1, 3, -1, 5, -1, 7, -1, 9]))
+        a = array.array(type, range(10))
+        a[::-4] = array.array(type, [10]*3)
+        vereq(a, array.array(type, [0, 10, 2, 3, 4, 10, 6, 7, 8 ,10]))
+        a = array.array(type, range(4))
+        a[::-1] = a
+        vereq(a, array.array(type, [3, 2, 1, 0]))
+        a = array.array(type, range(10))
+        b = a[:]
+        c = a[:]
+        ins = array.array(type, range(2))
+        a[2:3] = ins
+        b[slice(2,3)] = ins
+        c[2:3:] = ins
 
     # test that overflow exceptions are raised as expected for assignment
     # to array of specific integral types

Lib/test/test_types.py

@@ -410,6 +410,14 @@ vereq(a, [0, 10, 2, 3, 4, 10, 6, 7, 8 ,10])
 a = range(4)
 a[::-1] = a
 vereq(a, [3, 2, 1, 0])
+a = range(10)
+b = a[:]
+c = a[:]
+a[2:3] = ["two", "elements"]
+b[slice(2,3)] = ["two", "elements"]
+c[2:3:] = ["two", "elements"]
+vereq(a, b)
+vereq(a, c)
 
 print '6.6 Mappings == Dictionaries'
 d = {}

Modules/arraymodule.c

@@ -1478,6 +1478,179 @@ array_repr(arrayobject *a)
 	return s;
 }
 
+static PyObject*
+array_subscr(arrayobject* self, PyObject* item)
+{
+	if (PyInt_Check(item)) {
+		long i = PyInt_AS_LONG(item);
+		if (i < 0)
+			i += self->ob_size;
+		return array_item(self, i);
+	}
+	else if (PyLong_Check(item)) {
+		long i = PyLong_AsLong(item);
+		if (i == -1 && PyErr_Occurred())
+			return NULL;
+		if (i < 0)
+			i += self->ob_size;
+		return array_item(self, i);
+	}
+	else if (PySlice_Check(item)) {
+		int start, stop, step, slicelength, cur, i;
+		PyObject* result;
+		arrayobject* ar;
+		int itemsize = self->ob_descr->itemsize;
+
+		if (PySlice_GetIndicesEx((PySliceObject*)item, self->ob_size,
+				 &start, &stop, &step, &slicelength) < 0) {
+			return NULL;
+		}
+
+		if (slicelength <= 0) {
+			return newarrayobject(&Arraytype, 0, self->ob_descr);
+		}
+		else {
+			result = newarrayobject(&Arraytype, slicelength, self->ob_descr);
+			if (!result) return NULL;
+
+			ar = (arrayobject*)result;
+
+			for (cur = start, i = 0; i < slicelength; 
+			     cur += step, i++) {
+				memcpy(ar->ob_item + i*itemsize,
+				       self->ob_item + cur*itemsize,
+				       itemsize);
+			}
+			
+			return result;
+		}		
+	}
+	else {
+		PyErr_SetString(PyExc_TypeError, 
+				"list indices must be integers");
+		return NULL;
+	}
+}
+
+static int
+array_ass_subscr(arrayobject* self, PyObject* item, PyObject* value)
+{
+	if (PyInt_Check(item)) {
+		long i = PyInt_AS_LONG(item);
+		if (i < 0)
+			i += self->ob_size;
+		return array_ass_item(self, i, value);
+	}
+	else if (PyLong_Check(item)) {
+		long i = PyLong_AsLong(item);
+		if (i == -1 && PyErr_Occurred())
+			return -1;
+		if (i < 0)
+			i += self->ob_size;
+		return array_ass_item(self, i, value);
+	}
+	else if (PySlice_Check(item)) {
+		int start, stop, step, slicelength;
+		int itemsize = self->ob_descr->itemsize;
+
+		if (PySlice_GetIndicesEx((PySliceObject*)item, self->ob_size,
+				 &start, &stop, &step, &slicelength) < 0) {
+			return -1;
+		}
+
+		/* treat A[slice(a,b)] = v _exactly_ like A[a:b] = v */
+		if (step == 1 && ((PySliceObject*)item)->step == Py_None)
+			return array_ass_slice(self, start, stop, value);
+
+		if (value == NULL) {
+			/* delete slice */
+			int cur, i;
+			
+			if (slicelength <= 0)
+				return 0;
+
+			if (step < 0) {
+				stop = start + 1;
+				start = stop + step*(slicelength - 1) - 1;
+				step = -step;
+			}
+
+			for (cur = start, i = 0; cur < stop; 
+			     cur += step, i++) {
+				memmove(self->ob_item + (cur - i)*itemsize,
+					self->ob_item + (cur + 1)*itemsize,
+					(step - 1) * itemsize);
+			}
+			if (self->ob_size > (start + slicelength*step)) {
+				memmove(self->ob_item + (start + slicelength*(step - 1))*itemsize,
+					self->ob_item + (start + slicelength*step)*itemsize,
+					(self->ob_size - (start + slicelength*step))*itemsize);
+			}
+
+			self->ob_size -= slicelength;
+			self->ob_item = PyMem_REALLOC(self->ob_item, itemsize*self->ob_size);
+
+
+			return 0;
+		}
+		else {
+			/* assign slice */
+			int cur, i;
+			arrayobject* av;
+
+			if (!array_Check(value)) {
+				PyErr_Format(PyExc_TypeError,
+			     "must assign array (not \"%.200s\") to slice",
+					     value->ob_type->tp_name);
+				return -1;
+			}
+
+			av = (arrayobject*)value;
+
+			if (av->ob_size != slicelength) {
+				PyErr_Format(PyExc_ValueError,
+            "attempt to assign array of size %d to extended slice of size %d",
+					     av->ob_size, slicelength);
+				return -1;
+			}
+
+			if (!slicelength)
+				return 0;
+
+			/* protect against a[::-1] = a */
+			if (self == av) { 
+				value = array_slice(av, 0, av->ob_size);
+				av = (arrayobject*)value;
+			} 
+			else {
+				Py_INCREF(value);
+			}
+
+			for (cur = start, i = 0; i < slicelength; 
+			     cur += step, i++) {
+				memcpy(self->ob_item + cur*itemsize,
+				       av->ob_item + i*itemsize,
+				       itemsize);
+			}
+
+			Py_DECREF(value);
+			
+			return 0;
+		}
+	} 
+	else {
+		PyErr_SetString(PyExc_TypeError, 
+				"list indices must be integers");
+		return -1;
+	}
+}
+
+static PyMappingMethods array_as_mapping = {
+	(inquiry)array_length,
+	(binaryfunc)array_subscr,
+	(objobjargproc)array_ass_subscr
+};
+
 static int
 array_buffer_getreadbuf(arrayobject *self, int index, const void **ptr)
 {
@@ -1699,7 +1872,7 @@ statichere PyTypeObject Arraytype = {
 	(reprfunc)array_repr,			/* 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 */

Objects/listobject.c

@@ -1757,9 +1757,13 @@ list_ass_subscript(PyListObject* self, PyObject* item, PyObject* value)
 			return -1;
 		}
 
+		/* treat L[slice(a,b)] = v _exactly_ like L[a:b] = v */
+		if (step == 1 && ((PySliceObject*)item)->step == Py_None)
+			return list_ass_slice(self, start, stop, value);
+
 		if (value == NULL) {
 			/* delete slice */
-			PyObject **garbage, **item;
+			PyObject **garbage, **it;
 			int cur, i, j;
 			
 			if (slicelength <= 0)
@@ -1788,15 +1792,15 @@ list_ass_subscript(PyListObject* self, PyObject* item, PyObject* value)
 								cur + j + 1));
 				}
 			}
-			for (cur = start + slicelength*step + 1; 
+			for (cur = start + slicelength*step + 1;
 			     cur < self->ob_size; cur++) {
 				PyList_SET_ITEM(self, cur - slicelength,
 						PyList_GET_ITEM(self, cur));
 			}
 			self->ob_size -= slicelength;
-			item = self->ob_item;
-			NRESIZE(item, PyObject*, self->ob_size);
-			self->ob_item = item;
+			it = self->ob_item;
+			NRESIZE(it, PyObject*, self->ob_size);
+			self->ob_item = it;
 
 			for (i = 0; i < slicelength; i++) {
 				Py_DECREF(garbage[i]);