/*

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

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package com.sun.tools.internal.xjc.reader.gbind;

import java.util.ArrayList;

import java.util.Iterator;

import java.util.List;

/**

 * Represents one strongly-connected component

 * of the {@link Element} graph.

 *

 * @author Kohsuke Kawaguchi

 */

public final class ConnectedComponent implements Iterable<Element> {

    /**

     * {@link Element}s that belong to this component.

     */

    private final List<Element> elements = new ArrayList<Element>();

    /*package*/ boolean isRequired;

    /**

     * Returns true iff this {@link ConnectedComponent}

     * can match a substring whose length is greater than 1.

     *

     * <p>

     * That means this property will become a collection property.

     */

    public final boolean isCollection() {

        assert !elements.isEmpty();

        // a strongly connected component by definition has a cycle,

        // so if its size is bigger than 1 there must be a cycle.

        if(elements.size()>1)

            return true;

        // if size is 1, it might be still forming a self-cycle

        Element n = elements.get(0);

        return n.hasSelfLoop();

    }

    /**

     * Returns true iff this {@link ConnectedComponent}

     * forms a cut set of a graph.

     *

     * <p>

     * That means any valid element sequence must have at least

     * one value for this property.

     */

    public final boolean isRequired() {

        return isRequired;

    }

    /*package*/void add(Element e) {

        assert !elements.contains(e);

        elements.add(e);

    }

    public Iterator<Element> iterator() {

        return elements.iterator();

    }

    /**

     * Just produces debug representation

     */

    public String toString() {

        String s = elements.toString();

        if(isRequired())

            s += '!';

        if(isCollection())

            s += '*';

        return s;

    }

}