QualifiedName.java

/*
 * Copyright (C) 2010 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.web.controller;

/**
 * <p>
 * A qualified name that is a qualifier and a name. It can be seen as a simplified version of an XML QName that retains only the
 * prefix (qualifier) and the local name (name) and leaves out the namespace.
 * </p>
 *
 * <p>
 * Qualified names have a string representation that is equals to the concatenation of the qualifier and name separated by a
 * colon (:) character. When the
 * </p>
 *
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 */
public class QualifiedName implements Comparable<QualifiedName> {

    /**
     * Parse the string representation of a qname and returns a qualified name.
     *
     * @param qname the qname to parse
     * @return the corresponding qualified name
     * @throws java.lang.NullPointerException if the qname argument is null
     * @throws IllegalArgumentException if the qname argument contains more than one colon character
     */
    public static QualifiedName parse(String qname) throws IllegalArgumentException {
        if (qname == null) {
            throw new NullPointerException("No null argument accepted");
        }
        if (qname.length() > 0) {
            int index = qname.indexOf(':');
            if (index > -1) {
                return create(qname.substring(0, index), qname.substring(index + 1));
            }
        }
        return create(qname);
    }

    /**
     * Creates a qualified name.
     *
     * @param qualifier the qualifier
     * @param name the name
     * @return the qualified name
     * @throws NullPointerException if any argument is null
     * @throws IllegalArgumentException if any argument contains a colon character
     */
    public static QualifiedName create(String qualifier, String name) throws NullPointerException, IllegalArgumentException {
        return new QualifiedName(qualifier, name);
    }

    /**
     * Creates a qualified name with an empty string qualifier.
     *
     * @param name the name
     * @return the qualified name
     * @throws NullPointerException if any argument is null
     * @throws IllegalArgumentException if any argument contains a colon character
     */
    public static QualifiedName create(String name) throws NullPointerException, IllegalArgumentException {
        return new QualifiedName(name);
    }

    /** The qualifier. */
    private final String qualifier;

    /** The name. */
    private final String name;

    /** The cached hash code. */
    private int hashCode;

    private QualifiedName(String name) throws NullPointerException, IllegalArgumentException {
        this("", name);
    }

    private QualifiedName(String qualifier, String name) throws NullPointerException, IllegalArgumentException {
        if (qualifier == null) {
            throw new NullPointerException("No null prefix accepted");
        }
        if (qualifier.indexOf(':') != -1) {
            throw new IllegalArgumentException("The name '" + qualifier + "' must not contain a colon character");
        }
        if (name == null) {
            throw new NullPointerException("No null prefix accepted");
        }
        if (name.indexOf(':') != -1) {
            throw new IllegalArgumentException("The name '" + name + "' must not contain a colon character");
        }

        //
        this.qualifier = qualifier;
        this.name = name;
        this.hashCode = qualifier.hashCode() ^ name.hashCode();
    }

    /**
     * Returns the qualifier.
     *
     * @return the qualifier
     */
    public String getQualifier() {
        return qualifier;
    }

    /**
     * Returns the name.
     *
     * @return the name
     */
    public String getName() {
        return name;
    }

    /**
     * Returns the string representation.
     *
     * @return the string representation
     */
    public String getValue() {
        if (qualifier.isEmpty()) {
            return name;
        } else {
            return qualifier + ":" + name;
        }
    }

    @Override
    public int hashCode() {
        return hashCode;
    }

    @Override
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (obj instanceof QualifiedName) {
            QualifiedName that = (QualifiedName) obj;
            return qualifier.equals(that.qualifier) && name.equals(that.name);
        }
        return false;
    }

    public int compareTo(QualifiedName o) {
        if (o == null) {
            throw new NullPointerException("No null argument accepted");
        } else if (o == this) {
            return 0;
        } else {
            int qualifierComparison = qualifier.compareTo(o.qualifier);
            if (qualifierComparison == 0) {
                return name.compareTo(o.name);
            } else {
                return qualifierComparison;
            }
        }
    }

    @Override
    public String toString() {
        return "QualifiedName[prefix=" + qualifier + ",name=" + name + "]";
    }
}