Element

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package org.exolab.castor.xml.dtd;

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

/**
 * 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 final 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 Set<String> 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 final Hashtable<String, Attribute> attributes = new Hashtable<>();

  /**
   * 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;
  } // -- 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<String> getMixedContentChildren() {
    if (isMixedContent())
      return mixedChildren.iterator();
    return null;
  } // -- getMixedContentChildren

  /**
   * Returns enumeration of the attributes of the element.
   */
  public Enumeration<Attribute> 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