/* Woodstox XML processor
 *
 * Copyright (c) 2004 Tatu Saloranta, tatu.saloranta@iki.fi
 *
 * Licensed under the License specified in the file LICENSE which is
 * included with the source code.
 * You may not use this file except in compliance with the License.
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.ctc.wstx.dtd;

import com.ctc.wstx.util.PrefixedName;

Base class for validator Objects used to validate tree structure of an
XML-document against DTD.
/**
 * Base class for validator Objects used to validate tree structure of an
 * XML-document against DTD.
 */
public abstract class StructValidator
{
    
Method that should be called to get the actual usable validator
instance, from the 'template' validator.
/**
     * Method that should be called to get the actual usable validator
     * instance, from the 'template' validator.
     */
    public abstract StructValidator newInstance();

    
Method called when a new (start) element is encountered within the
scope of parent element this validator monitors.
Returns:
Null if element is valid in its current position; error
   message if not./**
     * Method called when a new (start) element is encountered within the
     * scope of parent element this validator monitors.
     *
     * @return Null if element is valid in its current position; error
     *    message if not.
     */
    public abstract String tryToValidate(PrefixedName elemName);

    
Method called when the end element of the scope this validator
validates is encountered. It should make sure that the content
model is valid, and if not, to construct an error message.
Returns:
Null if the content model for the element is valid; error
   message if not./**
     * Method called when the end element of the scope this validator
     * validates is encountered. It should make sure that the content
     * model is valid, and if not, to construct an error message.
     *
     * @return Null if the content model for the element is valid; error
     *    message if not.
     */
    public abstract String fullyValid();
}