Namespace.java :  » Ajax » zk » org » zkoss » idom » Java Open Source

/* Namespace.java


  Purpose: Namespace
  Description:
  History:
    2001/10/21 16:06:46, Create, Tom M. Yeh

Copyright (C) 2001 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
  This program is distributed under LGPL Version 3.0 in the hope that
  it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.idom;

import java.util.HashMap;
import java.util.Map;
import java.io.Serializable;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;

/**
 * Represents the namespace.
 * A namespace is immutable, so you have to get a new one
 *
 * @author tomyeh
 * @see Item
 */
public final class Namespace implements Serializable, Cloneable {
    private static final long serialVersionUID = 20060622L;

  /** The <code>Namespace</code> for when <i>not</i> in a namespace
   */
  public static final Namespace NO_NAMESPACE = newSpecialNamespace("", "");
  /** The xml namespace.
   */
  public static final Namespace XML_NAMESPACE = newSpecialNamespace(
      "xml", "http://www.w3.org/XML/1998/namespace");
  /** The xmlns namespace.
   */
  public static final Namespace XMLNS_NAMESPACE = newSpecialNamespace(
      "xmlns", "http://www.w3.org/XML/1998/namespace");

  /** The prefix mapped to this namespace */
  private String _prefix;
  /** The URI for this namespace */
  private String _uri;

  /** Returns the special namespace if prefix is special, or null if not.
   */
  public static Namespace getSpecial(String prefix) {
    if (prefix.equals("xml"))
      return Namespace.XML_NAMESPACE;
    if (prefix.equals("xmlns"))
      return Namespace.XMLNS_NAMESPACE;
    return null;
  }
    
  /** Assigns a spacial namespace whose name starts with xml.
   * We need it because the verifier will reject it.
   */
  private static final Namespace
  newSpecialNamespace(String prefix, String uri) {
    Namespace ns = new Namespace("", uri);
    ns._prefix = prefix; //assign directly to avoid checkNam...
    return ns;
  }

  /**
   * Contructor.
   *
   * @param prefix String prefix to map to this namespace.
   * @param uri String URI for namespace.
   * @exception DOMException with NAMESPACE_ERR if the given prefix and uri
   * is invalid
   */
  public Namespace(String prefix, String uri) {
    Verifier.checkNamespacePrefix(prefix, null);
    Verifier.checkNamespaceURI(uri, null);

    if (prefix.length() != 0 && uri.length() == 0)
      throw new DOMException(DOMException.NAMESPACE_ERR,
        "Non-empty prefix, "+prefix+", requires a URI");
    _prefix = prefix;
    _uri = uri;
  }

  /**
   * Gets the tag name of the giving local name.
   */
  public final String tagNameOf(String name) {
    assert(name.indexOf(':') < 0);

    int len = _prefix.length();
    return len == 0 ? name: _prefix + ':' + name;
  }

  /**
   * Gets the prefix mapped to this Namespace.
   */
  public final String getPrefix() {
    return _prefix;
  }
  /**
   * Gets the namespace URI for this Namespace.
   */
  public final String getURI() {
    return _uri;
  }

  /** Tests whether two namespace are the same in both prefix
   * and namespace URI.
   * On the other hand, equals check only the namespace URI.
   *
   * <p>Note: unlike equals, it throws DOMException if prefix
   * is the same but URI is different.
   *
   * @exception DOMException if they have the same prefix
   * but with different namespace URI
   */
  public final boolean equalsAll(Namespace ns) {
    if (_prefix.equals(ns._prefix))
      if (_uri.equals(ns._uri))
        return true;
      else
        throw new DOMException(DOMException.NAMESPACE_ERR,
          "The same prefix, " + _prefix + ", cannot have different URI: "+_uri+" vs "+ns._uri);
    return false;
  }

  //-- cloneable --//
  public Object clone() {
    try {
      return super.clone();
    } catch (CloneNotSupportedException e) {
      throw new InternalError();
    }
  }

  //-- Object --//
  /** Note: equals() is based on URI only. */
  public boolean equals(Object o) {
    return this == o
      || ((o instanceof Namespace) && _uri.equals(((Namespace)o)._uri));
  }
  /** Note: hashCode() is based on URI only. */
  public int hashCode() {
    return _uri.hashCode();
  }
  public String toString() {
    return "[Namespace: \"" + _prefix + "\", \"" + _uri + "\"]";
  }
}