001    /*
002     * JBoss, Home of Professional Open Source.
003     * Copyright 2008, Red Hat Middleware LLC, and individual contributors
004     * as indicated by the @author tags. See the copyright.txt file in the
005     * distribution for a full listing of individual contributors.
006     *
007     * This is free software; you can redistribute it and/or modify it
008     * under the terms of the GNU Lesser General Public License as
009     * published by the Free Software Foundation; either version 2.1 of
010     * the License, or (at your option) any later version.
011     *
012     * This software is distributed in the hope that it will be useful,
013     * but WITHOUT ANY WARRANTY; without even the implied warranty of
014     * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
015     * Lesser General Public License for more details.
016     *
017     * You should have received a copy of the GNU Lesser General Public
018     * License along with this software; if not, write to the Free
019     * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
020     * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
021     */
022    package org.jboss.dna.graph.properties;
023    
024    import java.util.Set;
025    import net.jcip.annotations.ThreadSafe;
026    
027    /**
028     * Registry of namespaces, which are used to provide isolated and independent domains for {@link Name names}.
029     *
030     * @author Randall Hauch
031     */
032    @ThreadSafe
033    public interface NamespaceRegistry {
034    
035        /**
036         * Return the namespace URI that is currently mapped to the empty prefix, or null if there is no current default namespace.
037         *
038         * @return the namespace URI that represents the default namespace, or null if there is no default namespace
039         */
040        String getDefaultNamespaceUri();
041    
042        /**
043         * Get the namespace URI for the supplied prefix.
044         *
045         * @param prefix the namespace prefix
046         * @return the namespace URI for the supplied prefix, or null if there is no namespace currently registered to use that prefix
047         * @throws IllegalArgumentException if the prefix is null
048         */
049        String getNamespaceForPrefix( String prefix );
050    
051        /**
052         * Return the prefix used for the supplied namespace URI.
053         *
054         * @param namespaceUri the namespace URI
055         * @param generateIfMissing true if the namespace URI has not already been registered and the method should auto-register the
056         *        namespace with a generated prefix, or false if the method should never auto-register the namespace
057         * @return the prefix currently being used for the namespace, or <code>null</code> if the namespace has not been registered
058         *         and <code>generateIfMissing</code> is <code>false</code>
059         * @throws IllegalArgumentException if the namespace URI is null
060         * @see #isRegisteredNamespaceUri(String)
061         */
062        String getPrefixForNamespaceUri( String namespaceUri,
063                                         boolean generateIfMissing );
064    
065        /**
066         * Return whether there is a registered prefix for the supplied namespace URI.
067         *
068         * @param namespaceUri the namespace URI
069         * @return true if the supplied namespace has been registered with a prefix, or false otherwise
070         * @throws IllegalArgumentException if the namespace URI is null
071         */
072        boolean isRegisteredNamespaceUri( String namespaceUri );
073    
074        /**
075         * Register a new namespace using the supplied prefix, returning the namespace URI previously registered under that prefix.
076         *
077         * @param prefix the prefix for the namespace, or null if a namesapce prefix should be generated automatically
078         * @param namespaceUri the namespace URI
079         * @return the namespace URI that was previously registered with the supplied prefix, or null if the prefix was not previously
080         *         bound to a namespace URI
081         * @throws IllegalArgumentException if the namespace URI is null
082         */
083        String register( String prefix,
084                         String namespaceUri );
085    
086        /**
087         * Obtain the set of namespaces that are registered.
088         *
089         * @return the set of
090         */
091        Set<String> getRegisteredNamespaceUris();
092    
093    }