t_not.java

中山大学编译原理课程的一个实验

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package symbols;

import exceptions.ExpressionException;
import exceptions.TypeMismatchedException;
import java.util.ArrayList;

/**
 *
 * @author Beeven
 */
public class T_NOT extends Terminal implements TerminalReduce{

    public Expr reduce(ArrayList<Expr> stack) throws ExpressionException {
        int post=stack.size()-1;
        Expr a=stack.get(post);
        if(!(a instanceof BoolExpr)) throw new TypeMismatchedException();
        BoolExpr be = new BoolExpr(!((BoolExpr)a).value);
        stack.remove(post);
        stack.remove(post-1);
        stack.add(be);
        return be;
    }

}