/*

 * 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.xml.internal.bind.v2.runtime;

import java.util.HashSet;

import java.util.IdentityHashMap;

import java.util.Map;

import java.util.Set;

/**

 * Bi-directional map between elements, inner peers,

 * and outer peers.

 *

 * <p>

 * TODO: this should be rewritten for efficiency.

 *

 * @since 2.0

 *

 * @author

 *     Kohsuke Kawaguchi (kohsuke.kawaguchi@sun.com)

 */

public final class AssociationMap<XmlNode> {

    final static class Entry<XmlNode> {

        /** XML element. */

        private XmlNode element;

        /** inner peer, or null. */

        private Object inner;

        /** outer peer, or null. */

        private Object outer;

        public XmlNode element() {

                return element;

        }

        public Object inner() {

                return inner;

        }

        public Object outer() {

                return outer;

        }

    }

    private final Map<XmlNode,Entry<XmlNode>> byElement = new IdentityHashMap<XmlNode,Entry<XmlNode>>();

    private final Map<Object,Entry<XmlNode>> byPeer = new IdentityHashMap<Object,Entry<XmlNode>>();

    private final Set<XmlNode> usedNodes = new HashSet<XmlNode>();

    public void addInner( XmlNode element, Object inner ) {

        Entry<XmlNode> e = byElement.get(element);

        if(e!=null) {

                if(e.inner!=null)

                byPeer.remove(e.inner);

            e.inner = inner;

        } else {

                e = new Entry<XmlNode>();

            e.element = element;

            e.inner = inner;

        }

        byElement.put(element,e);

        Entry<XmlNode> old = byPeer.put(inner,e);

        if(old!=null) {

            if(old.outer!=null)

                byPeer.remove(old.outer);

            if(old.element!=null)

                byElement.remove(old.element);

        }

    }

    public void addOuter( XmlNode element, Object outer ) {

        Entry<XmlNode> e = byElement.get(element);

        if(e!=null) {

            if(e.outer!=null)

                byPeer.remove(e.outer);

            e.outer = outer;

        } else {

            e = new Entry<XmlNode>();

            e.element = element;

            e.outer = outer;

        }

        byElement.put(element,e);

        Entry<XmlNode> old = byPeer.put(outer,e);

        if(old!=null) {

            old.outer=null;

            if(old.inner==null)

                // remove this entry

                byElement.remove(old.element);

        }

    }

    public void addUsed( XmlNode n ) {

        usedNodes.add(n);

    }

    public Entry<XmlNode> byElement( Object e ) {

        return byElement.get(e);

    }

    public Entry<XmlNode> byPeer( Object o ) {

        return byPeer.get(o);

    }

    public Object getInnerPeer( XmlNode element ) {

        Entry e = byElement(element);

        if(e==null)     return null;

        else            return e.inner;

    }

    public Object getOuterPeer( XmlNode element ) {

        Entry e = byElement(element);

        if(e==null)     return null;

        else            return e.outer;

    }

}