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 * this work for additional information regarding copyright ownership.
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 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
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package org.apache.xerces.xni.grammars;

 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.
The interaction works as follows:

When a validator considers a document, it is expected to request
grammars of the type it can handle from this object using the
retrieveInitialGrammarSet method. 
If it requires a grammar
not in this set, it will request it from this Object using the
retrieveGrammar method.  
 After successfully validating an
instance, the validator should make any new grammars it has compiled
available to this object using the cacheGrammars
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). 
 
 

Author:
Neil Graham, IBM
Version:
$Id: XMLGrammarPool.java 447245 2006-09-18 05:22:10Z mrglavas $/**
 * <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
 * @version $Id: XMLGrammarPool.java 447245 2006-09-18 05:22:10Z mrglavas $
 */

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>

    
 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. 
Params:
grammarType – the type of the grammar, from the
 org.apache.xerces.xni.grammars.Grammar interface.
Returns:
the set of grammars the validator may put in its "bucket"/**
     * <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>org.apache.xerces.xni.grammars.Grammar</code> interface.
     * @return the set of grammars the validator may put in its "bucket"
     */
    public Grammar[] retrieveInitialGrammarSet(String grammarType);

    
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. 
Params:
grammarType – the type of the grammars being returned;
grammars – an array containing the set of grammars being
 returned; order is not significant./** 
     * <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);

    
 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.  An application must not call its
EntityResolver itself from this method; this may result in infinite
recursions.
Params:
desc – The description of the Grammar being requested.
Returns:
the Grammar corresponding to this description or null if
 no such Grammar is known./** 
     * <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.
/**
     * 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.
/**
     * 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.
/**
     * Removes all grammars from the pool.
     */
    public void clear();
} // XMLGrammarPool