/*

 * reserved comment block

 * DO NOT REMOVE OR ALTER!

 */

/*

 * Licensed to the Apache Software Foundation (ASF) under one or more

 * contributor license agreements.  See the NOTICE file distributed with

 * this work for additional information regarding copyright ownership.

 * The ASF licenses this file to You under the Apache License, Version 2.0

 * (the "License"); you may not use this file except in compliance with

 * the License.  You may obtain a copy of the License at

 *

 *      http://www.apache.org/licenses/LICENSE-2.0

 *

 * 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.sun.org.apache.xerces.internal.xni.grammars;

/**

 * <p> This interface specifies how the parser and the application

 * interact with respect to Grammar objects that the application

 * possesses--either by having precompiled them or by having stored them

 * from a previous validation of an instance document.  It makes no

 * assumptions about the kind of Grammar involved, or about how the

 * application's storage mechanism works.</p>

 *

 * <p>The interaction works as follows:

 * <ul>

 * <li>When a validator considers a document, it is expected to request

 * grammars of the type it can handle from this object using the

 * <code>retrieveInitialGrammarSet</code> method. </li>

 * <li>If it requires a grammar

 * not in this set, it will request it from this Object using the

 * <code>retrieveGrammar</code> method.  </li>

 * <li> After successfully validating an

 * instance, the validator should make any new grammars it has compiled

 * available to this object using the <code>cacheGrammars</code>

 * method; for ease of implementation it may make other Grammars it holds references to as well (i.e.,

 * it may return some grammars that were retrieved from the GrammarPool in earlier operations). </li> </ul> </p>

 *

 * @author Neil Graham, IBM

 */

public interface XMLGrammarPool {

    // <p>we are trying to make this XMLGrammarPool work for all kinds of

    // grammars, so we have a parameter "grammarType" for each of the

    // methods. </p>

    /**

     * <p> retrieve the initial known set of grammars. this method is

     * called by a validator before the validation starts. the application

     * can provide an initial set of grammars available to the current

     * validation attempt. </p>

     * @param grammarType the type of the grammar, from the

     *  <code>com.sun.org.apache.xerces.internal.xni.grammars.Grammar</code> interface.

     * @return the set of grammars the validator may put in its "bucket"

     */

    public Grammar[] retrieveInitialGrammarSet(String grammarType);

    /**

     * <p>return the final set of grammars that the validator ended up

     * with.

     * This method is called after the

     * validation finishes. The application may then choose to cache some

     * of the returned grammars. </p>

     * @param grammarType the type of the grammars being returned;

     * @param grammars an array containing the set of grammars being

     *  returned; order is not significant.

     */

    public void cacheGrammars(String grammarType, Grammar[] grammars);

    /**

     * <p> This method requests that the application retrieve a grammar

     * corresponding to the given GrammarIdentifier from its cache.

     * If it cannot do so it must return null; the parser will then

     * call the EntityResolver.  <strong>An application must not call its

     * EntityResolver itself from this method; this may result in infinite

     * recursions.</strong>

     * @param desc The description of the Grammar being requested.

     * @return the Grammar corresponding to this description or null if

     *  no such Grammar is known.

     */

    public Grammar retrieveGrammar(XMLGrammarDescription desc);

    /**

     * Causes the XMLGrammarPool not to store any grammars when

     * the cacheGrammars(String, Grammar[[]) method is called.

     */

    public void lockPool();

    /**

     * Allows the XMLGrammarPool to store grammars when its cacheGrammars(String, Grammar[])

     * method is called.  This is the default state of the object.

     */

    public void unlockPool();

    /**

     * Removes all grammars from the pool.

     */

    public void clear();

} // XMLGrammarPool