gt:             for(ResultIterator iter : iterators){
context: /*
   * WANDORA
   * Knowledge Extraction, Management, and Publishing Application
   * http://wandora.org
   *
   * Copyright (C) 2004-2016 Wandora Team
   *
   * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * This program 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 General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *
   *
   * Join.java
   *
   */
  package org.wandora.query2;
  import java.util.*;
  
  /**
   *
   * @author olli
   */
  public class Join extends Directive implements DirectiveUIHints.Provider {
      private ArrayList<Directive> directives;
  
      public Join(){}
      
      public Join(Directive[] directives){
          this.directives=new ArrayList<Directive>();
          for(int i=0;i<directives.length;i++){
              this.directives.add(directives[i]);
          }
      }
  
      public Join(Directive d1,Directive d2){
          this(new Directive[]{d1,d2});
      }
      public Join(Directive d1,Directive d2,Directive d3){
          this(new Directive[]{d1,d2,d3});
      }
      public Join(Directive d1,Directive d2,Directive d3,Directive d4){
          this(new Directive[]{d1,d2,d3,d4});
      }
  
      @Override
      public DirectiveUIHints getUIHints() {
          DirectiveUIHints ret=new DirectiveUIHints(Join.class,new DirectiveUIHints.Constructor[]{
                  new DirectiveUIHints.Constructor(new DirectiveUIHints.Parameter[]{
                          new DirectiveUIHints.Parameter(Directive.class, true, "directives"),
                  }, ""),
              },
              Directive.getStandardAddonHints(),
              "Join",
              "Framework");
          return ret;
      }       
      @Override
      public boolean startQuery(QueryContext context) throws QueryException {
          boolean r=true;
          for(Directive d : directives){
              r&=d.startQuery(context);
          }
          return r;
      }
      @Override
      public void endQuery(QueryContext context) throws QueryException {
          for(Directive d : directives){
              d.endQuery(context);
          }
      }
  
  
      @Override
      public Directive join(Directive directive){
          this.directives.add(directive);
          return this;
      }
  /*
      @Override
      public ArrayList<ResultRow> query(QueryContext context,ResultRow input,String as) throws QueryException {
          ArrayList<ArrayList<ResultRow>> res=new ArrayList<ArrayList<ResultRow>>();
  
          for(Directive d: directives){
              ArrayList<ResultRow> r=d.query(context,input,null);
              res.add(r);
          }
  
          ArrayList<ResultRow> ret=new ArrayList<ResultRow>();
  
          int[] pointers=new int[res.size()];
          for(int i=0;i<pointers.length;i++) pointers[i]=0;
          Outer: while(true){
              ResultRow row=null;
              for(int i=0;i<pointers.length;i++){
                  if(i==0) row=res.get(0).get(pointers[0]);
                  else{
                      row=row.join(res.get(i).get(pointers[i]));
                  }
              }
              ret.add(row);
  
              for(int i=pointers.length-1;i>=-1;i--){
                  if(i==-1){
                      break Outer;
                  }
  
                  pointers[i]++;
                  if(pointers[i]>=res.get(i).size()){
                      pointers[i]=0;
                      continue;
                  }
                  else break;
              }
          }
  
          return ret;
      }
  */
  
      @Override
      public ResultIterator queryIterator(QueryContext context,ResultRow input) throws QueryException {
          return new JoinIterator(context,input);
      }
  
      @Override
      public boolean isStatic(){
          for(Directive d : directives){
              if(!d.isStatic()) return false;
          }
          return true;
      }
  
      public String debugStringParams(String indent){
          return debugStringInner(directives,indent);
      }
  
  
      private class JoinIterator extends ResultIterator {
          public QueryContext context;
          public ResultRow input;
  
          public ArrayList<ResultIterator> iterators;
          public boolean allDone=false;
  
          public ResultRow nextRow;
          public ResultRow[] rows;
  
          public int counter=0;
  
          public long startTime=0;
  
          public JoinIterator(QueryContext context,ResultRow input) throws QueryException {
              this.context=context;
              this.input=input;
  
              iterators=new ArrayList<ResultIterator>();
              
              for(int i=0;i<directives.size();i++){
                  ResultIterator iter=directives.get(i).queryIterator(context,input);
                  if(i>0 && !(iter instanceof ResultIterator.EmptyIterator)
                         && !(iter instanceof ResultIterator.SingleIterator)
                         && !(iter instanceof ResultIterator.ListIterator)
                         && !(iter instanceof ResultIterator.CachedIterator) )
                      iter=new ResultIterator.CachedIterator(iter);
                  iterators.add(iter);
              }
              rows=new ResultRow[iterators.size()];
              for(int i=0;i<rows.length;i++){
                  if(!iterators.get(i).hasNext()){
                      allDone=true;
                      break;
                  }
                  else rows[i]=iterators.get(i).next();
              }
  
              nextRow=null;
          }
  
          public boolean hasNext() throws QueryException {
              if(nextRow!=null) return true;
              if(allDone) return false;
              if(context.checkInterrupt()) throw new QueryException("Execution interrupted");
  
  //            if(counter==0) startTime=System.currentTimeMillis();
  
              ResultRow row=null;
              for(int i=0;i<rows.length;i++){
                  if(row==null){
                      row=rows[i];
                  }
                  else if(rows[i]!=null) {
                      row=row.join(rows[i]);
                  }
              }
              if(row==null) return false;
              nextRow=row;
  //            counter++;
  //            if((counter%50000)==0){
  //                double speed=50000.0/(double)(System.currentTimeMillis()-startTime)*1000.0;
  //                System.out.println("Join counter "+counter+" "+speed);
  //                startTime=System.currentTimeMillis();
  //            }
  
              for(int i=iterators.size()-1;i>=0;i--){
                  ResultIterator iter=iterators.get(i);
                  if(iter.hasNext()){
                      rows[i]=iter.next();
                      break;
                  }
                  else{
                      if(i==0){
                          allDone=true;
                          break;
                      }
                      else{
                          iter.reset();
                          rows[i]=null;
                          if(iter.hasNext()) rows[i]=iter.next();
                          continue;
                      }
                  }
              }
              return true;
          }
  
          public ResultRow next() throws QueryException,NoSuchElementException {
              if(hasNext()){
                  ResultRow temp=nextRow;
                  nextRow=null;
                  return temp;
              }
              else throw new NoSuchElementException();
          }
  
          public void dispose() throws QueryException {
              for(ResultIterator iter : iterators){
                  iter.dispose();
              }
          }
  
          public void reset() throws QueryException {
  