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 * Copyright 2001 (C) Intalio, Inc. All Rights Reserved.
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 * $Id$
 */


package org.exolab.castor.xml.schema;

import java.util.Enumeration;
import java.util.Vector;

import org.exolab.castor.xml.ValidationException;
import org.exolab.castor.xml.validators.ValidationUtils;

/**
 * The base class for the XML Schema Identity Constraints (key, keyref, unique).
 *
 * @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 abstract class IdentityConstraint extends Annotated {


  /**
   * Identity Constraint id
   **/
  private String _id = null;

  /**
   * Identity Constraint name
   **/
  private String _name = null;

  /**
   * Identity Constraint Selector
   **/
  private IdentitySelector _selector = null;

  /**
   * The fields of this Identity Constraint
   **/
  private final Vector<IdentityField> _fields = new Vector<>(3);

  /**
   * Constructor used by sub-classes. Creates a new IdentityConstraint.
   *
   * @param name the name for the IdentityConstraint. Must not be null.
   **/
  protected IdentityConstraint(String name) throws SchemaException {
    setName(name);
  } // -- IdentityConstraint

  /**
   * Adds the given IdentityField to this IdentityConstraint
   *
   * @param field the IdentityField to add.
   **/
  public void addField(IdentityField field) {
    if (field != null)
      _fields.add(field);
  } // -- addField

  /**
   * Returns an Enumeration of the IdentityFields contained within this IdentityConstraint.
   *
   * @return an Enumeration of the IdentityField objects contain within this IdentityConstraint.
   **/
  public Enumeration<IdentityField> getFields() {
    return _fields.elements();
  } // -- getFields

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

  /**
   * Returns the name of this IdentityConstraint. This value will never be null.
   *
   * @return the name of this IdentityConstraint
   **/
  public String getName() {
    return _name;
  } // -- getName

  /**
   * Returns the selector of this IdentityConstraint.
   *
   * @return the IdentitySelector of this IdentityConstraint
   **/
  public IdentitySelector getSelector() {
    return _selector;
  } // -- getSelector

  /**
   * Removes the given IdentityField from this IdentityConstraint.
   *
   * @return true if the IdentityField was contained within this IdentityConstraint, otherwise
   *         false.
   **/
  public boolean removeField(IdentityField field) {
    return _fields.remove(field);
  } // -- removeField


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

  /**
   * Sets the name for this IdentityConstraint.
   *
   * @param name the name for this IdentityConstraint. Must not be null.
   * @exception SchemaException if name is null.
   **/
  public void setName(String name) throws SchemaException {
    if (name == null)
      throw new SchemaException("The name of an IdentityConstraint must not be null.");

    _name = name;
  } // -- setName

  /**
   * Sets the selector for this IdentityConstraint.
   *
   * @param selector the Selector for this IdentityConstraint. Must not be null.
   * @exception SchemaException if selector is null.
   **/
  public void setSelector(IdentitySelector selector) throws SchemaException {
    if (selector == null)
      throw new SchemaException("The selector of an IdentityConstraint must not be null.");
    _selector = selector;
  } // -- setSelector

  /**
   * Returns the type of this Schema Structure
   * 
   * @return the type of this Schema Structure
   **/
  public abstract short getStructureType();

  /**
   * Checks the validity of this Schema defintion.
   * 
   * @exception ValidationException when this Schema definition is invalid.
   **/
  public void validate() throws ValidationException {
    String err = null;

    // -- name must be a NCName
    if (!ValidationUtils.isNCName(_name)) {
      err = "The name of an IdentityConstraint must be an NCName.";
    }
    // -- selector must exist
    else if (_selector == null) {
      err = "Selector for IdentityConstraint cannot be null.";
    }
    // -- at least 1 (one) field must exist
    else if (_fields.size() < 1) {
      err = "There must be at least one 'field' in an " + "identity constraint.";
    }

    if (err != null)
      throw new ValidationException(err);

  } // -- validate

} // -- class IdentityConstraint
