/*
 * Copyright (C) 2004-2011
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package org.kohsuke.rngom.digested;

import java.util.Iterator;


/**
 * A pattern that can contain other patterns.
 *
 * @author Kohsuke Kawaguchi (kk@kohsuke.org)
 */
public abstract class DContainerPattern extends DPattern implements Iterable<DPattern> {
    private DPattern head;
    private DPattern tail;

    public DPattern firstChild() {
        return head;
    }

    public DPattern lastChild() {
        return tail;
    }

    public int countChildren() {
        int i=0;
        for( DPattern p=firstChild(); p!=null; p=p.next)
            i++;
        return i;
    }

    public Iterator<DPattern> iterator() {
        return new Iterator<DPattern>() {
            DPattern next = head;
            public boolean hasNext() {
                return next!=null;
            }

            public DPattern next() {
                DPattern r = next;
                next = next.next;
                return r;
            }

            public void remove() {
                throw new UnsupportedOperationException();
            }
        };
    }

    void add( DPattern child ) {
        if(tail==null) {
            child.prev = child.next = null;
            head = tail = child;
        } else {
            child.prev = tail;
            tail.next = child;
            child.next = null;
            tail = child;
        }
    }
}