// THIS PROGRAM WILL ONLY COMPILE WITH JDK 1.8 OR LATER
/////////////////////////////////////////////////////////////////
// SAMPLE SUBCLASS OF FSM4: DFA to recognized regular expression a(a|b)*b
// 4 states, state 2 is accept state, state 3 is 'dead state'.  Should
// set keeprunning to true and skipbadinput to false.

import java.util.HashMap;
public class dfa4 extends FSM4<Character>  // will cast chars to strings
{
    String instring; // input string
    int ci; // current char position in instring
    HashMap<Character,Integer> Hash; // for implementing getindex
    public dfa4(String x)
	{
	    instring = x;
	    ci = 0; // current character in instring.
	    numstates = 4;  // state 0 is always start state
	    maxinputs = 2;  // input restricted to 'a', 'b'
	    setTable();
	}
    protected void setTable()
    {
	// set hash table mapping input to row index (for getindex)
	Hash = new HashMap<Character,Integer>();
	Hash.put('a',0);  Hash.put('b',1);
	// set action table (M declared in FSM4)
	M = new action[numstates][maxinputs];
	int a = 0, b = 1; // for convenience
	M[0][a] = () -> 1; 
	//M[0][a]=new action() { public int act() { return 1; } }; //before 1.8
	M[0][b] = () -> { return 3; };
	M[1][a] = () -> 1;  // same as { return 1; }
	M[1][b] = () -> 2; 
	M[2][a] = () -> 1;
	M[2][b] = () -> 2;
	for(int i=a;i<=b;i++) M[3][i] = () -> 3; // dead state
    }//setStateTable

    protected boolean acceptState(int s)  { return s==2; }
    protected int getindex(Character x)  { return Hash.get(x); }
    protected Character nextInput() // gets next available input, null if none
    {
	if (ci > instring.length()-1) return null;
	else return instring.charAt(ci++);
    }

    public static void main(String[] argv)
    {
	dfa4 automaton = new dfa4(argv[0]);  // take command line input
	automaton.trace = true; // prints current input and state
	automaton.keeprunning = true;  // process entire input
	automaton.skipbadinput = false; // terminates on invalid input
	boolean result = automaton.run();
	System.out.println(result);
    }

}//dfa4