Change the SBValue.linked_list_iter() to treat the value object as a homogeneous linked list data structure

where an empty linked list is represented as a value object with a NULL value, instead of a special value
object which 'points' to NULL.

Also modifies the test case to comply.

rdar://problem/9933692

llvm-svn: 137289

lldb/scripts/Python/modify-python-lldb.py

@@ -95,7 +95,7 @@ linked_list_iter_def = '''
         Return True if val is invalid or it corresponds to a null pointer.
         Otherwise, return False.
         """
-        if not val or int(val.GetValue(), 0) == 0:
+        if not val or val.GetValueAsUnsigned() == 0:
             return True
         else:
             return False
@@ -127,8 +127,10 @@ linked_list_iter_def = '''
         for t in task_head.linked_list_iter('next'):
             print t
         """
+        if end_of_list_test(self):
+            return
+        item = self
         try:
-            item = self.GetChildMemberWithName(next_item_name)
             while not end_of_list_test(item):
                 yield item
                 # Prepare for the next iteration.

lldb/test/python_api/value/linked_list/main.cpp

@@ -21,14 +21,14 @@ public:
 
 int main (int argc, char const *argv[])
 {
-    Task *task_head = new Task(-1, NULL);
+    Task *task_head = NULL;
     Task *task1 = new Task(1, NULL);
     Task *task2 = new Task(2, NULL);
     Task *task3 = new Task(3, NULL); // Orphaned.
     Task *task4 = new Task(4, NULL);
     Task *task5 = new Task(5, NULL);
 
-    task_head->next = task1;
+    task_head = task1;
     task1->next = task2;
     task2->next = task4;
     task4->next = task5;
@@ -43,7 +43,7 @@ int main (int argc, char const *argv[])
     printf("We have a total number of %d tasks\n", total);
 
     // This corresponds to an empty task list.
-    Task *empty_task_head = new Task(-1, NULL);
+    Task *empty_task_head = NULL;
 
     return 0; // Break at this line
 }