import java.util.*;

public class ArbreSyntaxiqueSynchronise extends ArbreSyntaxique {

    private boolean racine = false;

    public ArbreSyntaxiqueSynchronise(String [] lexemes) 
	throws ErreurSyntaxiqueException
    {
	super(lexemes);
	racine = true;
    }

    public synchronized int valeur() {
	return super.valeur();
    }

    public synchronized void miseAJour() {
	super.miseAJour();
	if (racine) {
	    System.out.println("resultat = " + valeur());
	}
    }

    public static void main(String[] args) {
	try {
	    new Operateur("+", 2) {
		    public int evaluer(int [] operandes) {
			return operandes[0] + operandes[1];
		    }
		};
	    new Operateur("-", 2) {
		    public int evaluer(int [] operandes) {
			return operandes[0] - operandes[1];
		    }
		};
	    VariableThread a = new VariableThread("a", 0, 1);
	    VariableThread b = new VariableThread("b", 2, 2);
	    VariableThread c = new VariableThread("c", 4, 3);
	    ArbreSyntaxique arbre = new ArbreSyntaxiqueSynchronise(args);

	    System.out.println("pour " + a + ", " + b + ", " + c + " resultat = " + arbre.valeur());
	    new Thread(a).start();
	    new Thread(b).start();
	    new Thread(c).start();
	} catch (ErreurSyntaxiqueException e) {
	    throw new Error(e.getMessage());
	} catch (OperateurExistantException e) {
	    throw new Error(e.getMessage());
	}
    }
}