Backend refactoring: KjcEngine has been split up into separate classes for preprocessing, compiling, and running.

app/PdeMessageConsumer.java

@@ -0,0 +1,15 @@
+// -*- Mode: JDE; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+
+// Different instances of PdeMessageStream need to do different things with
+// messages.  In particular, a stream instance used for parsing output from
+// the compiler compiler has to interpret its messages differently than one
+// parsing output from the runtime.
+//
+// Classes which consume messages and do something with them should implement
+// this interface.
+//
+public interface PdeMessageConsumer {
+
+  public void message(String s);
+
+}