Copyright (c) 2004-2011 QOS.ch
All rights reserved.
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.
/**
 * Copyright (c) 2004-2011 QOS.ch
 * All rights reserved.
 *
 * 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.slf4j.helpers;

import java.util.Iterator;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

import org.slf4j.Marker;

A simple implementation of the Marker interface. 
Author:
Ceki Gülcü, Joern Huxhorn/**
 * A simple implementation of the {@link Marker} interface.
 * 
 * @author Ceki Gülcü
 * @author Joern Huxhorn
 */
public class BasicMarker implements Marker {

    private static final long serialVersionUID = -2849567615646933777L;
    private final String name;
    private List<Marker> referenceList = new CopyOnWriteArrayList<Marker>();

    BasicMarker(String name) {
        if (name == null) {
            throw new IllegalArgumentException("A marker name cannot be null");
        }
        this.name = name;
    }

    public String getName() {
        return name;
    }

    public void add(Marker reference) {
        if (reference == null) {
            throw new IllegalArgumentException("A null value cannot be added to a Marker as reference.");
        }

        // no point in adding the reference multiple times
        if (this.contains(reference)) {
            return;

        } else if (reference.contains(this)) { // avoid recursion
            // a potential reference should not hold its future "parent" as a reference
            return;
        } else {
            referenceList.add(reference);
        }
    }

    public boolean hasReferences() {
        return (referenceList.size() > 0);
    }

    public boolean hasChildren() {
        return hasReferences();
    }

    public Iterator<Marker> iterator() {
      return referenceList.iterator();
    }

    public boolean remove(Marker referenceToRemove) {
        return referenceList.remove(referenceToRemove);
    }

    public boolean contains(Marker other) {
        if (other == null) {
            throw new IllegalArgumentException("Other cannot be null");
        }

        if (this.equals(other)) {
            return true;
        }

        if (hasReferences()) {
            for (Marker ref : referenceList) {
                if (ref.contains(other)) {
                    return true;
                }
            }
        }
        return false;
    }

    
This method is mainly used with Expression Evaluators.
/**
     * This method is mainly used with Expression Evaluators.
     */
    public boolean contains(String name) {
        if (name == null) {
            throw new IllegalArgumentException("Other cannot be null");
        }

        if (this.name.equals(name)) {
            return true;
        }

        if (hasReferences()) {
            for (Marker ref : referenceList) {
                if (ref.contains(name)) {
                    return true;
                }
            }
        }
        return false;
    }

    private static String OPEN = "[ ";
    private static String CLOSE = " ]";
    private static String SEP = ", ";

    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (!(obj instanceof Marker))
            return false;

        final Marker other = (Marker) obj;
        return name.equals(other.getName());
    }

    public int hashCode() {
        return name.hashCode();
    }

    public String toString() {
        if (!this.hasReferences()) {
            return this.getName();
        }
        Iterator<Marker> it = this.iterator();
        Marker reference;
        StringBuilder sb = new StringBuilder(this.getName());
        sb.append(' ').append(OPEN);
        while (it.hasNext()) {
            reference = it.next();
            sb.append(reference.getName());
            if (it.hasNext()) {
                sb.append(SEP);
            }
        }
        sb.append(CLOSE);

        return sb.toString();
    }
}