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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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package javax.xml.namespace;

import java.util.Iterator;

/**

 * <p>Interface for read only XML Namespace context processing.</p>

 *

 * <p>An XML Namespace has the properties:</p>

 * <ul>

 *   <li>Namespace URI:

 *       Namespace name expressed as a URI to which the prefix is bound</li>

 *   <li>prefix: syntactically, this is the part of the attribute name

 *       following the <code>XMLConstants.XMLNS_ATTRIBUTE</code>

 *       ("xmlns") in the Namespace declaration</li>

 * </ul>

 * <p>example:

 * <code>&lt;element xmlns:prefix="http://Namespace-name-URI"&gt;</code></p>

 *

 * <p>All <code>get*(*)</code> methods operate in the current scope

 * for Namespace URI and prefix resolution.</p>

 *

 * <p>Note that a Namespace URI can be bound to

 * <strong>multiple</strong> prefixes in the current scope.  This can

 * occur when multiple <code>XMLConstants.XMLNS_ATTRIBUTE</code>

 * ("xmlns") Namespace declarations occur in the same Start-Tag and

 * refer to the same Namespace URI. e.g.<br />

 * <pre>

 * <element xmlns:prefix1="http://Namespace-name-URI"

 *          xmlns:prefix2="http://Namespace-name-URI">

 * </pre>

 * This can also occur when the same Namespace URI is used in multiple

 * <code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns") Namespace

 * declarations in the logical parent element hierarchy.  e.g.<br />

 * <pre>

 * <parent xmlns:prefix1="http://Namespace-name-URI">

 *   <child xmlns:prefix2="http://Namespace-name-URI">

 *     ...

 *   </child>

 * </parent>

 * </pre></p>

 *

 * <p>A prefix can only be bound to a <strong>single</strong>

 * Namespace URI in the current scope.</p>

 *

 * @author <a href="mailto:Jeff.Suttor@Sun.com">Jeff Suttor</a>

 * @see javax.xml.XMLConstants

 *   javax.xml.XMLConstants for declarations of common XML values

 * @see <a href="http://www.w3.org/TR/xmlschema-2/#QName">

 *   XML Schema Part2: Datatypes</a>

 * @see <a href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">

 *   Namespaces in XML</a>

 * @see <a href="http://www.w3.org/XML/xml-names-19990114-errata">

 *   Namespaces in XML Errata</a>

 * @since 1.5

 */

public interface NamespaceContext {

    /**

     * <p>Get Namespace URI bound to a prefix in the current scope.</p>

     *

     * <p>When requesting a Namespace URI by prefix, the following

     * table describes the returned Namespace URI value for all

     * possible prefix values:</p>

     *

     * <table border="2" rules="all" cellpadding="4">

     *   <thead>

     *     <tr>

     *       <td align="center" colspan="2">

     *         <code>getNamespaceURI(prefix)</code>

     *         return value for specified prefixes

     *       </td>

     *     </tr>

     *     <tr>

     *       <td>prefix parameter</td>

     *       <td>Namespace URI return value</td>

     *     </tr>

     *   </thead>

     *   <tbody>

     *     <tr>

     *       <td><code>DEFAULT_NS_PREFIX</code> ("")</td>

     *       <td>default Namespace URI in the current scope or

     *         <code>{@link

     *         javax.xml.XMLConstants#NULL_NS_URI XMLConstants.NULL_NS_URI("")}

     *         </code>

     *         when there is no default Namespace URI in the current scope</td>

     *     </tr>

     *     <tr>

     *       <td>bound prefix</td>

     *       <td>Namespace URI bound to prefix in current scope</td>

     *     </tr>

     *     <tr>

     *       <td>unbound prefix</td>

     *       <td>

     *         <code>{@link

     *         javax.xml.XMLConstants#NULL_NS_URI XMLConstants.NULL_NS_URI("")}

     *         </code>

     *       </td>

     *     </tr>

     *     <tr>

     *       <td><code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>

     *       <td><code>XMLConstants.XML_NS_URI</code>

     *           ("http://www.w3.org/XML/1998/namespace")</td>

     *     </tr>

     *     <tr>

     *       <td><code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>

     *       <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>

     *         ("http://www.w3.org/2000/xmlns/")</td>

     *     </tr>

     *     <tr>

     *       <td><code>null</code></td>

     *       <td><code>IllegalArgumentException</code> is thrown</td>

     *     </tr>

     *    </tbody>

     * </table>

     *

     * @param prefix prefix to look up

     *

     * @return Namespace URI bound to prefix in the current scope

     *

     * @throws IllegalArgumentException When <code>prefix</code> is

     *   <code>null</code>

     */

    String getNamespaceURI(String prefix);

    /**

     * <p>Get prefix bound to Namespace URI in the current scope.</p>

     *

     * <p>To get all prefixes bound to a Namespace URI in the current

     * scope, use {@link #getPrefixes(String namespaceURI)}.</p>

     *

     * <p>When requesting a prefix by Namespace URI, the following

     * table describes the returned prefix value for all Namespace URI

     * values:</p>

     *

     * <table border="2" rules="all" cellpadding="4">

     *   <thead>

     *     <tr>

     *       <th align="center" colspan="2">

     *         <code>getPrefix(namespaceURI)</code> return value for

     *         specified Namespace URIs

     *       </th>

     *     </tr>

     *     <tr>

     *       <th>Namespace URI parameter</th>

     *       <th>prefix value returned</th>

     *     </tr>

     *   </thead>

     *   <tbody>

     *     <tr>

     *       <td>&lt;default Namespace URI&gt;</td>

     *       <td><code>XMLConstants.DEFAULT_NS_PREFIX</code> ("")

     *       </td>

     *     </tr>

     *     <tr>

     *       <td>bound Namespace URI</td>

     *       <td>prefix bound to Namespace URI in the current scope,

     *           if multiple prefixes are bound to the Namespace URI in

     *           the current scope, a single arbitrary prefix, whose

     *           choice is implementation dependent, is returned</td>

     *     </tr>

     *     <tr>

     *       <td>unbound Namespace URI</td>

     *       <td><code>null</code></td>

     *     </tr>

     *     <tr>

     *       <td><code>XMLConstants.XML_NS_URI</code>

     *           ("http://www.w3.org/XML/1998/namespace")</td>

     *       <td><code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>

     *     </tr>

     *     <tr>

     *       <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>

     *           ("http://www.w3.org/2000/xmlns/")</td>

     *       <td><code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>

     *     </tr>

     *     <tr>

     *       <td><code>null</code></td>

     *       <td><code>IllegalArgumentException</code> is thrown</td>

     *     </tr>

     *   </tbody>

     * </table>

     *

     * @param namespaceURI URI of Namespace to lookup

     *

     * @return prefix bound to Namespace URI in current context

     *

     * @throws IllegalArgumentException When <code>namespaceURI</code> is

     *   <code>null</code>

     */

    String getPrefix(String namespaceURI);

    /**

     * <p>Get all prefixes bound to a Namespace URI in the current

     * scope.</p>

     *

     * <p>An Iterator over String elements is returned in an arbitrary,

     * <strong>implementation dependent</strong>, order.</p>

     *

     * <p><strong>The <code>Iterator</code> is

     * <em>not</em> modifiable.  e.g. the

     * <code>remove()</code> method will throw

     * <code>UnsupportedOperationException</code>.</strong></p>

     *

     * <p>When requesting prefixes by Namespace URI, the following

     * table describes the returned prefixes value for all Namespace

     * URI values:</p>

     *

     * <table border="2" rules="all" cellpadding="4">

     *   <thead>

     *     <tr>

     *       <th align="center" colspan="2"><code>

     *         getPrefixes(namespaceURI)</code> return value for

     *         specified Namespace URIs</th>

     *     </tr>

     *     <tr>

     *       <th>Namespace URI parameter</th>

     *       <th>prefixes value returned</th>

     *     </tr>

     *   </thead>

     *   <tbody>

     *     <tr>

     *       <td>bound Namespace URI,

     *         including the &lt;default Namespace URI&gt;</td>

     *       <td>

     *         <code>Iterator</code> over prefixes bound to Namespace URI in

     *         the current scope in an arbitrary,

     *         <strong>implementation dependent</strong>,

     *         order

     *       </td>

     *     </tr>

     *     <tr>

     *       <td>unbound Namespace URI</td>

     *       <td>empty <code>Iterator</code></td>

     *     </tr>

     *     <tr>

     *       <td><code>XMLConstants.XML_NS_URI</code>

     *           ("http://www.w3.org/XML/1998/namespace")</td>

     *       <td><code>Iterator</code> with one element set to

     *         <code>XMLConstants.XML_NS_PREFIX</code> ("xml")</td>

     *     </tr>

     *     <tr>

     *       <td><code>XMLConstants.XMLNS_ATTRIBUTE_NS_URI</code>

     *           ("http://www.w3.org/2000/xmlns/")</td>

     *       <td><code>Iterator</code> with one element set to

     *         <code>XMLConstants.XMLNS_ATTRIBUTE</code> ("xmlns")</td>

     *     </tr>

     *     <tr>

     *       <td><code>null</code></td>

     *       <td><code>IllegalArgumentException</code> is thrown</td>

     *     </tr>

     *   </tbody>

     * </table>

     *

     * @param namespaceURI URI of Namespace to lookup

     *

     * @return <code>Iterator</code> for all prefixes bound to the

     *   Namespace URI in the current scope

     *

     * @throws IllegalArgumentException When <code>namespaceURI</code> is

     *   <code>null</code>

     */

    Iterator getPrefixes(String namespaceURI);

}