automata.DA: allow incrementally adding states

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@12041 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/src/automata/DA.java

@@ -73,6 +73,14 @@ public class DA<Symbol, Acceptance extends AcceptanceOmega>
 		}
 	}
 
+	/**
+	 * Construct a DRA with zero states, use addState to add states.
+	 */
+	public DA()
+	{
+		this(0);
+	}
+
 	/**
 	 * Construct a DRA of fixed size (i.e. fixed number of states).
 	 */
@@ -109,6 +117,17 @@ public class DA<Symbol, Acceptance extends AcceptanceOmega>
 
 	// Mutators
 
+	/**
+	 * Add a state.
+	 * @return index of the fresh state
+	 */
+	public int addState()
+	{
+		edges.add(new ArrayList<Edge>());
+		size++;
+		return size-1;
+	}
+
 	/**
 	 * Set the start state (index)
 	 */