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/*
 * Copyright 2002-2007 the original author or authors.
 *
 * Licensed 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 net.sf.json;

import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.io.Writer;
import java.io.IOException;

import net.sf.json.util.JsonEventListener;
import net.sf.json.util.JSONUtils;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * Base class for JSONObject and JSONArray.
 *
 * @author Andres Almiray 
 */
abstract class AbstractJSON implements JSON {
   // private static Set cycleSet = new HashSet();

   private static ThreadLocal cycleSet = new ThreadLocal(){
      protected synchronized Object initialValue() {
         return new HashSet();
      }
   };

   private static final Log log = LogFactory.getLog( AbstractJSON.class );

   /**
    * Adds a reference for cycle detection check.
    *
    * @param instance the reference to add
    * @return true if the instance has not been added previously, false
    *        otherwise.
    */
   protected static boolean addInstance( Object instance ) {
      return getCycleSet().add( instance );
   }

   /**
    * Fires an end of array event.
    */
   protected static void fireArrayEndEvent( JsonConfig jsonConfig ) {
      if( jsonConfig.isEventTriggeringEnabled() ){
         for( Iterator listeners = jsonConfig.getJsonEventListeners()
               .iterator(); listeners.hasNext(); ){
            JsonEventListener listener = (JsonEventListener) listeners.next();
            try{
               listener.onArrayEnd();
            }catch( RuntimeException e ){
               log.warn( e );
            }
         }
      }
   }

   /**
    * Fires a start of array event.
    */
   protected static void fireArrayStartEvent( JsonConfig jsonConfig ) {
      if( jsonConfig.isEventTriggeringEnabled() ){
         for( Iterator listeners = jsonConfig.getJsonEventListeners()
               .iterator(); listeners.hasNext(); ){
            JsonEventListener listener = (JsonEventListener) listeners.next();
            try{
               listener.onArrayStart();
            }catch( RuntimeException e ){
               log.warn( e );
            }
         }
      }
   }

   /**
    * Fires an element added event.
    *
    * @param index the index where the element was added
    * @param element the added element
    */
   protected static void fireElementAddedEvent( int index, Object element, JsonConfig jsonConfig ) {
      if( jsonConfig.isEventTriggeringEnabled() ){
         for( Iterator listeners = jsonConfig.getJsonEventListeners()
               .iterator(); listeners.hasNext(); ){
            JsonEventListener listener = (JsonEventListener) listeners.next();
            try{
               listener.onElementAdded( index, element );
            }catch( RuntimeException e ){
               log.warn( e );
            }
         }
      }
   }

   /**
    * Fires an error event.
    *
    * @param jsone the thrown exception
    */
   protected static void fireErrorEvent( JSONException jsone, JsonConfig jsonConfig ) {
      if( jsonConfig.isEventTriggeringEnabled() ){
         for( Iterator listeners = jsonConfig.getJsonEventListeners()
               .iterator(); listeners.hasNext(); ){
            JsonEventListener listener = (JsonEventListener) listeners.next();
            try{
               listener.onError( jsone );
            }catch( RuntimeException e ){
               log.warn( e );
            }
         }
      }
   }

   /**
    * Fires an end of object event.
    */
   protected static void fireObjectEndEvent( JsonConfig jsonConfig ) {
      if( jsonConfig.isEventTriggeringEnabled() ){
         for( Iterator listeners = jsonConfig.getJsonEventListeners()
               .iterator(); listeners.hasNext(); ){
            JsonEventListener listener = (JsonEventListener) listeners.next();
            try{
               listener.onObjectEnd();
            }catch( RuntimeException e ){
               log.warn( e );
            }
         }
      }
   }

   /**
    * Fires a start of object event.
    */
   protected static void fireObjectStartEvent( JsonConfig jsonConfig ) {
      if( jsonConfig.isEventTriggeringEnabled() ){
         for( Iterator listeners = jsonConfig.getJsonEventListeners()
               .iterator(); listeners.hasNext(); ){
            JsonEventListener listener = (JsonEventListener) listeners.next();
            try{
               listener.onObjectStart();
            }catch( RuntimeException e ){
               log.warn( e );
            }
         }
      }
   }

   /**
    * Fires a property set event.
    *
    * @param key the name of the property
    * @param value the value of the property
    * @param accumulated if the value has been accumulated over 'key'
    */
   protected static void firePropertySetEvent( String key, Object value, boolean accumulated,
         JsonConfig jsonConfig ) {
      if( jsonConfig.isEventTriggeringEnabled() ){
         for( Iterator listeners = jsonConfig.getJsonEventListeners()
               .iterator(); listeners.hasNext(); ){
            JsonEventListener listener = (JsonEventListener) listeners.next();
            try{
               listener.onPropertySet( key, value, accumulated );
            }catch( RuntimeException e ){
               log.warn( e );
            }
         }
      }
   }

   /**
    * Fires a warning event.
    *
    * @param warning the warning message
    */
   protected static void fireWarnEvent( String warning, JsonConfig jsonConfig ) {
      if( jsonConfig.isEventTriggeringEnabled() ){
         for( Iterator listeners = jsonConfig.getJsonEventListeners()
               .iterator(); listeners.hasNext(); ){
            JsonEventListener listener = (JsonEventListener) listeners.next();
            try{
               listener.onWarning( warning );
            }catch( RuntimeException e ){
               log.warn( e );
            }
         }
      }
   }

   /**
    * Removes a reference for cycle detection check.
    */
   protected static void removeInstance( Object instance ) {
      getCycleSet().remove( instance );
   }

   private static Set getCycleSet() {
      return (Set) cycleSet.get();
   }

    public final Writer write(Writer writer) throws IOException {
        write(writer,NORMAL);
        return writer;
    }

    public final Writer writeCanonical(Writer writer) throws IOException {
        write(writer,CANONICAL);
        return writer;
    }

    protected abstract void write(Writer w, WritingVisitor v) throws IOException;

    interface WritingVisitor {
        void on(JSON o, Writer w) throws IOException;
        void on(Object value, Writer w) throws IOException;
    }

    private static final WritingVisitor NORMAL = new WritingVisitor() {
        public void on(JSON o, Writer w) throws IOException {
            o.write(w);
        }

        public void on(Object value, Writer w) throws IOException {
            w.write(JSONUtils.valueToString(value));
        }
    };

    private static final WritingVisitor CANONICAL = new WritingVisitor() {
        public void on(JSON o, Writer w) throws IOException {
            o.writeCanonical(w);
        }

        public void on(Object value, Writer w) throws IOException {
            w.write(JSONUtils.valueToCanonicalString(value));
        }
    };
}