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 *
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 * must also contain a copy of this document.
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 * without prior written permission of Intalio, Inc. For written permission, please contact
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 * 4. Products derived from this Software may not be called "Exolab" nor may "Exolab" appear in
 * their names without prior written permission of Intalio, Inc. Exolab is a registered trademark of
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 *
 * 5. Due credit should be given to the Exolab Project (http://www.exolab.org/).
 *
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 *
 * Copyright 2001 (C) Intalio, Inc. All Rights Reserved.
 *
 * $Id$
 */


package org.exolab.castor.xml.schema;

import org.exolab.castor.xml.ValidationException;

/**
 * A class which represents the field selector for an IdentityConstraint
 *
 * @author <a href="mailto:kvisco@intalio.com">Keith Visco</a>
 * @version $Revision$ $Date: 2006-04-14 04:14:43 -0600 (Fri, 14 Apr 2006) $
 **/
public class IdentityField extends Annotated {
  /** SerialVersionUID */
  private static final long serialVersionUID = -1385357135959672473L;

  /**
   * Identity Field id (optional)
   **/
  private String _id = null;

  /**
   * XPath expression for field nodes (required)
   **/
  private String _xpath = null;

  /**
   * Creates a new IdentityField.
   *
   * @param xpath the xpath for the IdentityField. Must not be null.
   * @exception SchemaException if xpath is null.
   **/
  public IdentityField(String xpath) throws SchemaException {
    setXPath(xpath);
  } // -- IdentityField

  /**
   * Returns the Id of this IdentityField, or null if no Id has been set.
   *
   * @return the Id of this IdentityField, or null if no Id has been set.
   **/
  public String getId() {
    return _id;
  } // -- getId

  /**
   * Returns the XPath of this IdentityField. This value will never be null.
   *
   * @return the XPath of this IdentityField.
   **/
  public String getXPath() {
    return _xpath;
  } // -- getXPath


  /**
   * Sets the Id for this IdentityField.
   *
   * @param id the Id for this IdentityField.
   **/
  public void setId(String id) {
    _id = id;
  } // -- setId

  /**
   * Sets the XPath expression for this Field.
   *
   * @param xpath the XPath expression for this IdentityField. Must not be null.
   * @exception SchemaException if xpath is null.
   **/
  public void setXPath(String xpath) throws SchemaException {
    if (xpath == null)
      throw new SchemaException("The xpath of a 'field' must not be null.");

    _xpath = xpath;
  } // -- setXPath

  /**
   * Returns the type of this Schema Structure
   * 
   * @return the type of this Schema Structure
   **/
  public short getStructureType() {
    return Structure.IDENTITY_FIELD;
  } // -- getStructureType

  /**
   * Checks the validity of this Schema defintion.
   * 
   * @exception ValidationException when this Schema definition is invalid.
   **/
  public void validate() throws ValidationException {
    // -- do nothing, if it can be constructed, it's valid.
    // -- validate XPath expression in the future?
  } // -- validate

} // -- class: IdentityField
