package adql.search;
import java.util.Stack;
/*
* This file is part of ADQLLibrary.
*
* ADQLLibrary is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* ADQLLibrary is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with ADQLLibrary. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2012,2016 - UDS/Centre de Données astronomiques de Strasbourg (CDS),
* Astronomisches Rechen Institut (ARI)
*/
import adql.query.ADQLIterator;
import adql.query.ADQLObject;
/**
* <p>Lets searching and replacing ADQL objects which match with the condition defined in the function {@link #match(ADQLObject)}.</p>
* <ul>
* <li>By default, this replace handler does not search recursively (that's to say, it does not search in sub-queries).</li>
* <li>By default, this replace handler does not stop to the first matching object.</li>
* <li>The matching objects are simply collected in an ArrayList.</li>
* <li>Matching objects are collected before their replacement.</li>
* </ul>
*
* @author Grégory Mantelet (CDS;ARI)
* @version 1.4 (05/2016)
*
* @see RemoveHandler
*/
public abstract class SimpleReplaceHandler extends SimpleSearchHandler implements IReplaceHandler {
/** Count matching objects which have been replaced successfully. */
protected int nbReplacement = 0;
/**
* <p>Builds a SimpleReplaceHandler:</p>
* <ul>
* <li>not recursive,</li>
* <li>and which does not stop at the first match.</li>
* </ul>
*/
public SimpleReplaceHandler(){
super();
}
/**
* Builds a SimpleReplaceHandler which does not stop at the first match.
*
* @param recursive <i>true</i> to search also in sub-queries, <i>false</i> otherwise.
*/
public SimpleReplaceHandler(boolean recursive){
super(recursive);
}
/**
* Builds a SimpleReplaceHandler.
*
* @param recursive <i>true</i> to search also in sub-queries, <i>false</i> otherwise.
* @param onlyFirstMatch <i>true</i> to stop at the first match, <i>false</i> otherwise.
*/
public SimpleReplaceHandler(boolean recursive, boolean onlyFirstMatch){
super(recursive, onlyFirstMatch);
}
@Override
public int getNbReplacement(){
return nbReplacement;
}
@Override
protected void reset(){
super.reset();
nbReplacement = 0;
}
/**
* <p>Adds the given ADQL object as one result of the research, and then replace its reference
* inside its parent.</p>
*
* <p>Thus, the matched item added in the list is no longer available in its former parent.</p>
*
* <p><b><u>Warning:</u> the second parameter (<i>it</i>) may be <i>null</i> if the given match is the root search object itself.</b></p>
*
* @param matchObj An ADQL object which has matched to the research criteria.
* @param it The iterator from which the matched ADQL object has been extracted.
*
* @return The match item after replacement if any replacement has occurred,
* or <code>null</code> if the item has been removed,
* or the object given in parameter if there was no replacement.
*/
protected ADQLObject addMatchAndReplace(ADQLObject matchObj, ADQLIterator it){
super.addMatch(matchObj, it);
if (it != null){
try{
ADQLObject replacer = getReplacer(matchObj);
if (replacer == null)
it.remove();
else
it.replace(replacer);
nbReplacement++;
return replacer;
}catch(IllegalStateException ise){
}catch(UnsupportedOperationException uoe){
}
}
return matchObj;
}
@Override
public void searchAndReplace(final ADQLObject startObj){
reset();
if (startObj == null)
return;
// Test the root search object:
if (match(startObj))
addMatch(startObj, null);
Stack<ADQLIterator> stackIt = new Stack<ADQLIterator>();
ADQLObject obj = null;
ADQLIterator it = startObj.adqlIterator();
while(!isFinished()){
// Fetch the next ADQL object to test:
do{
if (it != null && it.hasNext())
obj = it.next();
else if (!stackIt.isEmpty())
it = stackIt.pop();
else
return;
}while(obj == null);
// Add the current object if it is matching:
if (match(obj))
obj = addMatchAndReplace(obj, it);
// Continue the research inside the current object (or the new object if a replacement has been performed):
if (obj != null && goInto(obj)){
stackIt.push(it);
it = obj.adqlIterator();
}
obj = null;
}
}
/**
* <p>Gets (generate on the fly or not) an ADQLObject which must replace the given one (expected to be an ADQLObject that has matched).</p>
*
* <p><b><u>IMPORTANT:</u> It is the responsibility of the object which calls this method to apply the replacement !</b></p>
*
* <p><i><u>Note:</u> If the returned value is </i>null<i> it may be interpreted as a removal of the matched ADQL object. Note also that it is
* still the responsibility of the object which calls this method to apply the removal !</i></p>
*
* @param objToReplace The ADQL item to replace.
*
* @return The replacement ADQL item.
*
* @throws UnsupportedOperationException If the this method must not be used.
*/
protected abstract ADQLObject getReplacer(ADQLObject objToReplace) throws UnsupportedOperationException;
}