Element

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 * $Id$
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package org.exolab.castor.xml.dtd;

import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Enumeration;

/**
 * Implementation of DTD Element declaration specification.
 * @author <a href="mailto:totok@intalio.com">Alexander Totok</a>
 * @version $Revision$ $Date: 2006-04-25 15:08:23 -0600 (Tue, 25 Apr 2006) $
 */
public class Element {

   private static final short ANY = 0;
   private static final short EMPTY = 1;
   private static final short MIXED = 2;
   private static final short ELEMENTS_ONLY = 3;

   /**
    * Name of the element.
    */
   private String name;

   /**
    * DTD document owning this element
    */
   private DTDdocument document;

   /**
    * Content type of the element. Value may be {@link #ANY ANY}, {@link #EMPTY EMPTY},
    * {@link #MIXED MIXED}, {@link #ELEMENTS_ONLY ELEMENTS_ONLY} or
    * -1, if unspecified.
    */
   private short contentType = -1;

   /**
    * Set of names of children of the element,
    * if the element has <tt>MIXED</tt> content.
    */
   private HashSet mixedChildren = null;

   /**
    * Content Particle representing content of the element, if the element has
    * <tt>ELEMENTS_ONLY</tt> content.
    */
   private ContentParticle content = null;

   /**
    * Attributes of the element.
    */
   private Hashtable attributes;

   /**
    * Constructor, setting the name of the element and owning DTD document.
    * @param document must not be null.
    */
   public Element(DTDdocument document, String name) {

      if (document == null) {
         String err = "Element constructor: document must not be null.";
         throw new IllegalArgumentException(err);
      }

      this.name = name;
      this.document = document;
      attributes = new Hashtable();
   } //-- Element

   /**
    * Constructor, setting owning DTD document of the element.
    * @param document must not be null.
    */
   public Element(DTDdocument document) {
      this(document, null);
   } //-- Element

   /**
    * Returns the name of the element.
    */
   public String getName() {
      return name;
   } //-- getName

   /**
    * Returns DTD document owning this element.
    */
   public DTDdocument getDocument() {
      return document;
   } //-- getDocument

   /**
    * Returns {@link java.util.Iterator iterator} of the set of mixed children,
    * if of <tt>MIXED</tt> content, <tt>null</tt> otherwise.
    */
   public Iterator getMixedContentChildren() {
      if (isMixedContent()) return mixedChildren.iterator();
      return null;
   } //-- getMixedContentChildren

   /**
    * Returns enumeration of the attributes of the element.
    */
   public Enumeration getAttributes() {
      return attributes.elements();
   } //-- getAttributes

   /**
    * Returns {@link org.exolab.castor.xml.dtd.ContentParticle Content Particle},
    * representing the content of the element, if has <tt>ELEMENTS_ONLY</tt>
    * content, <tt>null</tt> otherwise.
    */
   public ContentParticle getContent() {
      if (isElemOnlyContent()) return content;
      return null;
   } //-- getContent

   /**
    * Sets the name of the element.
    */
   public void setName(String name) {
      this.name = name;
   } //-- setName

   /**
    * Sets the content type of the element to <tt>ANY</tt>.
    */
   public void setAnyContent() {
      contentType = ANY;
   } //-- setAnyContent

   /**
    * <b>True</b> if the element is of <tt>ANY</tt> content type,
    * <b>false</b> otherwise.
    */
   public boolean isAnyContent() {
      return contentType == ANY;
   } //-- isAnyContent

   /**
    * Sets the content type of the element to <tt>EMPTY</tt>.
    */
   public void setEmptyContent() {
      contentType = EMPTY;
   } //-- setEmptyContent

   /**
    * <b>True</b> if the element is of <tt>EMPTY</tt> content type, <b>false</b> otherwise.
    */
   public boolean isEmptyContent() {
      return contentType == EMPTY;
   } //-- isEmptyContent

   /**
    * Sets the content type of the element to <tt>MIXED</tt>.
    */
   public void setMixedContent() {
      contentType = MIXED;
      mixedChildren = new HashSet();
   } //-- setMixedContent

   /**
    * <b>True</b> if the element is of <tt>MIXED</tt> content type, <b>false</b> otherwise.
    */
   public boolean isMixedContent() {
      return contentType == MIXED;
   } //-- isMixedContent

   /**
    * Sets the content type of the element to <tt>ELEMENTS_ONLY</tt>.
    * @param cp Content Particle representing content of the element.
    */
   public void setElemOnlyContent(ContentParticle cp) {
      contentType = ELEMENTS_ONLY;
      content = cp;
   } //-- setChildrenContent

   /**
    * <b>True</b> if the element is of <tt>ELEMENTS_ONLY</tt> content type,
    * <b>false</b> otherwise.
    */
   public boolean isElemOnlyContent() {
      return contentType == ELEMENTS_ONLY;
   } //-- isChildrenContent

   /**
    * Adds name of a <tt>child</tt> to the set of children's names.
    * @throws DTDException if there already exists the child with the same name.
    */
   public synchronized void addMixedContentChild(String child) throws DTDException {
      if (mixedChildren.contains(child)) {
         String err = "Element \"" + name + "\" already contains child element ";
         err += "\"" + child + "\".";
         throw new DTDException(err);
      }
      mixedChildren.add(child);
   } //-- addChild

   /**
    * Adds attribute to the element. If the element already has the attribute
    * with the same name, does nothing.
    */
   public synchronized void addAttribute(Attribute attribute) {
      String name = attribute.getName();
      if (!attributes.containsKey(name)) attributes.put(name,attribute);
   } //-- addAttribute

} //-- Element