Throw an IndexError when given an extended slice;

Jonathan Brandmeyer · Jonathan Brandmeyer · commit 7187c6132a99 · 2004-03-17T03:15:35.000Z
Clip bounds of slices in a mannar consistant with builtin containers;
Prevent undefined behavior within the STL when given certain kinds of
empty slices.


[SVN r22507]
diff --git a/include/boost/python/suite/indexing/detail/indexing_suite_detail.hpp b/include/boost/python/suite/indexing/detail/indexing_suite_detail.hpp
@@ -13,6 +13,7 @@
 # include <boost/detail/binary_search.hpp>
 # include <vector>
 # include <map>
+#include <iostream>
 
 namespace boost { namespace python { namespace detail {
 
@@ -507,9 +508,9 @@ namespace boost { namespace python { namespace detail {
         static object
         base_get_item_(back_reference<Container&> const& container, PyObject* i)
         { 
-            // Proxy  
+            // Proxy
             Index idx = DerivedPolicies::convert_index(container.get(), i);
-            
+
             if (PyObject* shared = 
                 ContainerElement::get_links().find(container.get(), idx))
             {
@@ -570,15 +571,42 @@ namespace boost { namespace python { namespace detail {
         base_get_slice_data(
             Container& container, PySliceObject* slice, Index& from, Index& to)
         {
-            if (Py_None == slice->start)
-                from = DerivedPolicies::get_min_index(container);
-            else 
-                from = DerivedPolicies::convert_index(container, slice->start);
+            if (Py_None != slice->step) {
+                PyErr_SetString( PyExc_IndexError, "slice step size not supported.");
+                throw_error_already_set();
+            }
 
-            if (Py_None == slice->stop)
+            Index min_index = DerivedPolicies::get_min_index(container);
+            Index max_index = DerivedPolicies::get_max_index(container);
+            
+            
+            if (Py_None == slice->start) {
+                from = min_index;
+            }
+            else {
+                from = extract<long>( slice->start);
+                if (from < 0) // Negative slice index
+                    from += max_index;
+                if (from < 0) // Clip lower bounds to zero
+                    from = 0;
+                if (from > max_index) // Clip upper bounds to max_index.
+                    from = max_index;
+                
+            }
+
+            if (Py_None == slice->stop) {
                 to = DerivedPolicies::get_max_index(container);
-            else 
-                to = DerivedPolicies::convert_index(container, slice->stop);
+            }
+            else {
+                to = extract<long>( slice->stop);
+                if (to < 0)
+                    to += max_index;
+                if (to < 0)
+                    to = 0;
+                if (to > max_index)
+                    to = max_index;
+            }
+		
         }        
    
         static void 
diff --git a/include/boost/python/suite/indexing/vector_indexing_suite.hpp b/include/boost/python/suite/indexing/vector_indexing_suite.hpp
@@ -81,6 +81,8 @@ namespace boost { namespace python {
         static object 
         get_slice(Container& container, index_type from, index_type to)
         { 
+            if (from > to)
+	            return object(Container());
             return object(Container(container.begin()+from, container.begin()+to));
         }
 
@@ -94,17 +96,27 @@ namespace boost { namespace python {
         set_slice(Container& container, index_type from, 
             index_type to, data_type const& v)
         { 
-            container.erase(container.begin()+from, container.begin()+to);
-            container.insert(container.begin()+from, v);
+            if (from > to) {
+                return;
+            }
+            else {
+                container.erase(container.begin()+from, container.begin()+to);
+                container.insert(container.begin()+from, v);
+            }
         }
 
         template <class Iter>
         static void 
         set_slice(Container& container, index_type from, 
             index_type to, Iter first, Iter last)
         { 
-            container.erase(container.begin()+from, container.begin()+to);
-            container.insert(container.begin()+from, first, last);
+            if (from > to) {
+                container.insert(container.begin()+from, first, last);
+            }
+            else {
+                container.erase(container.begin()+from, container.begin()+to);
+                container.insert(container.begin()+from, first, last);
+            }
         }
 
         static void 
@@ -116,6 +128,10 @@ namespace boost { namespace python {
         static void 
         delete_slice(Container& container, index_type from, index_type to)
         { 
+            if (from > to) {
+                // A null-op.
+                return;
+            }
             container.erase(container.begin()+from, container.begin()+to);
         }
         
