aspect InsertOverrideMCUs {
	public void Program.insertOverrideMCUs() {
		//use a hashmap to weed out modules with duplicate names 
		HashMap<String, ModuleCompilationUnit> collectedMCUs = 
				new HashMap<String, ModuleCompilationUnit>();
		  
		for (Iterator<CompilationUnit> cuIterator = getCompilationUnitList().iterator();
				cuIterator.hasNext();) {
			CompilationUnit cu = cuIterator.next();
			if (!(cu instanceof ModuleCompilationUnit)) {
				continue;
			}
			ModuleCompilationUnit mcu = (ModuleCompilationUnit) cu; 
			Set<ModuleCompilationUnit> newMCUs = mcu.createOverrideMCUs();
			for (ModuleCompilationUnit currMCU : newMCUs) {
				collectedMCUs.put(currMCU.getModuleName(), currMCU);
			} 
		}
		for (ModuleCompilationUnit mcu : collectedMCUs.values()) {
			getCompilationUnitList().add(mcu);
		}
	}
	
	public Set<ModuleCompilationUnit> ModuleCompilationUnit.createOverrideMCUs() {
		Set<ModuleCompilationUnit> ret = new HashSet<ModuleCompilationUnit>();
		for (ModuleAccess access : getModuleDecl().getOverridesList()) {
			if (getHostProgram().lookupModuleCUNoTransform(access) != null) {
				continue;
			}
			ModuleCompilationUnit newMCU = new ModuleCompilationUnit(
					"", //packagedecl
					new List(), //imports
					new List(), //types
					new ModuleDecl(new ModuleAccess(access.getID()),
						new Opt(),
						new List(),
						new List()),
					new List(),
					new List()
					);
			newMCU.setFromSource(true);
			newMCU.setRelativeName("synthetic " + access.getID());
			newMCU.setPathName(".");
			newMCU.setBaseCU(newMCU);
					
			newMCU.setSynthetic(true);
			ret.add(newMCU);
		}
		return ret;
	}
}