AbstractSeq.java

/*
 * Vitry, copyright (C) Hans Hoglund 2011
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * See COPYING.txt for details.
 */
package vitry.runtime.struct;

import java.util.Iterator;

import vitry.Build;
import vitry.runtime.Function;


abstract public class AbstractSeq<T> implements Seq<T>
{
    public boolean isNil()
    {
        return false;
    }

    public boolean hasTail()
    {
        return !Seqs.isNil(this.tail());
    }

    public Seq<T> prepend(T head)
    {
        return new PairSeq<T>(head, this);
    }

    public <U> Seq<U> map(Function fn)
    {
        if (Build.MEMOIZE_SEQUENCES)
        {
            return new MemoizedSeq<U>(new MappedSeq<T, U>(fn, this));
        }
        else
        {
            return new MappedSeq<T, U>(fn, this);
        }
    }

    public Iterator<T> iterator()
    {
        return new SeqIterator<T>(this);
    }

    public SeqIterator<T> seqIterator()
    {
        return new SeqIterator<T>(this);
    }

    public String toString()
    {
        return Seqs.printable(this).toString();
    }
}