public class Iterative {

    public static BitList complement( BitList in ) {

        BitList result;
        result = new BitList();

        Iterator i = in.iterator();
        Iterator j = result.iterator();

        if ( ! i.hasNext() ) {

            j.add( BitList.ONE );

        } else {

            while ( i.hasNext() ) {
                int bit = i.next();

                if ( bit == BitList.ONE ) {
                    j.add( BitList.ZERO );
                } else {
                    j.add( BitList.ONE );
                }
            }

        }

        return result;
    }

    public static BitList or( BitList a, BitList b ) {

        BitList result;
        result = new BitList();

        Iterator i = a.iterator();
        Iterator j = b.iterator();

        Iterator k = result.iterator();

        if ( ! i.hasNext() ) {
             throw new IllegalArgumentException( "a is empty" );
        }
        if ( ! j.hasNext() ) {
             throw new IllegalArgumentException( "b is empty" );
        }
        while ( i.hasNext() ) {

            if ( ! j.hasNext() ) {
                throw new IllegalArgumentException( "b is shorter than a" );
            }
            int iBit = i.next();
            int jBit = j.next();
            
            if ( iBit == BitList.ONE || jBit == BitList.ONE ) {
                k.add( BitList.ONE );
            } else {
                k.add( BitList.ZERO );
            }
        }

        if ( j.hasNext() ) {
            throw new IllegalArgumentException( "b is longer than a" );
        }
        return result;
    }

    public static void main( String[] args ) {

        BitList a, b;

        for ( int i=0; i<args.length; i++ ) {

            a = new BitList( args[i] );
            System.out.println( "> " + a );
            System.out.println( "< " + complement( a ) );
            System.out.println();

        }

        a = new BitList( "10001" );
        b = new BitList( "00011" );

        System.out.println( "a = " + a );
        System.out.println( "b = " + b );
        System.out.println( "a or b = " + or( a, b ) );

    }
}

// > java Iterative 1011 "" 01 0000111
//
// > 1011
// < 0100
// 
// > 0
// < 1
// 
// > 01
// < 10
// 
// > 0000111
// < 1111000