- Write interface for History and ConcreteHistory

- Write interface for HistoryObserver
- Remove obsolete interfaces


git-svn-id: svn://svn.gna.org/svn/sgpemv2/trunk@690 3ecf2c5c-341e-0410-92b4-d18e462d057c

src/backend/ready_queue.cc

@@ -29,15 +29,15 @@ void
 ReadyQueue::swap(position a, position b)
 	throw (std::out_of_range)
 {
-	size_t size = _scheds.size();
-	if(a > size || b > size) 
-		throw std::out_of_range(_("Trying to access a Schedulable "
-															"with an index outside of the "
-															"queue limits."));
 	if(a == b) return;
-
-	Schedulable* temp = _scheds[a];
-	_scheds[a] = _scheds[b];
+	
+	// Usage of "at()" isn't casual: 
+	// at() checks indexes, "[]" doesn't.
+	// Once we've done the check once, we
+	// can assume it's safe to use "[]";
+	// this for performance reasons.
+	Schedulable* temp = _scheds.at(a);
+	_scheds[a] = _scheds.at(b);
 	_scheds[b] = temp;
 }
 
@@ -53,11 +53,8 @@ sgpem::Schedulable&
 ReadyQueue::get_item_at(position index)
 	throw (std::out_of_range)
 {
-	if(index > size())
-		throw std::out_of_range(_("Trying to access a Schedulable "
-															"with an index outside of the "
-															"queue limits."));
-	return *(_scheds[index]);
+	// Checks index access
+	return *_scheds.at(index);
 }