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Library that provides facilities to allow project information to be manipulated in Java and .Net. Supports a range of data formats: Microsoft Project Exchange (MPX), Microsoft Project (MPP,MPT), Microsoft Project Data Interchange (MSPDI XML), Microsoft Project Database (MPD), Planner (XML), Primavera (PM XML, XER, and database), Asta Powerproject (PP, MDB), Asta Easyplan (PP), Phoenix Project Manager (PPX), FastTrack Schedule (FTS), and the Standard Data Exchange Format (SDEF).

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/*
 * Copyright 2013 Jon Iles
 *
 * 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 com.rtfparserkit.parser.standard;

import java.util.ArrayDeque;
import java.util.Deque;

import com.rtfparserkit.parser.IRtfListener;

/**
 * Default parser event handler. Passes events to the listener. In this implementation
 * the events are queued to allow later events to modify earlier events before they are
 * passed to the listener. For example, we coalesce consecutive string events together.
 */
class DefaultEventHandler implements IParserEventHandler
{
   /**
    * Constructor.
    */
   public DefaultEventHandler(IRtfListener listener)
   {
      this.listener = listener;
   }

   /**
    * If we've reached the end of the document, flush all queued events to 
    * the listener and pass on the document end event.
    * If we have received consecutive string events, coalesce them into
    * a single event in the buffer.
    * If the buffer has reached its maximum size, remove the event from the
    * front of the buffer and pass this to the listener. 
    */
   @Override
   public void handleEvent(IParserEvent event)
   {
      if (event.getType() == ParserEventType.DOCUMENT_END_EVENT)
      {
         flushEvents();
         event.fire(listener);
      }
      else
      {
         IParserEvent lastEvent = events.peekLast();
         if (lastEvent != null && lastEvent.getType() == ParserEventType.STRING_EVENT && event.getType() == ParserEventType.STRING_EVENT)
         {
            event = mergeStringEvents((StringEvent) event);
         }

         events.add(event);

         if (events.size() > MAX_EVENTS)
         {
            events.removeFirst().fire(listener);
         }
      }
   }

   /**
    * It's always valid for this handler to continue processing events,
    * so we always return false.
    */
   @Override
   public boolean isComplete()
   {
      return false;
   }

   /**
    * Allows the caller to see the event at the end of the buffer.
    */
   @Override
   public IParserEvent getLastEvent()
   {
      return events.getLast();
   }

   /**
    * Allows the caller to remove the last event from the buffer.
    */
   @Override
   public void removeLastEvent()
   {
      events.removeLast();
   }

   /**
    * Removes the string event from the end of the buffer, merges it with the string
    * event we've just received, and adds the new event to the end of the buffer.
    */
   private IParserEvent mergeStringEvents(StringEvent event)
   {
      StringEvent lastEvent = (StringEvent) events.removeLast();
      StringEvent newEvent = new StringEvent(lastEvent.getString() + event.getString());
      return newEvent;
   }

   /**
    * Passes any remaining events in the buffer to the listener and clears the event buffer,
    */
   private void flushEvents()
   {
      for (IParserEvent event : events)
      {
         event.fire(listener);
      }
      events.clear();
   }

   private static final int MAX_EVENTS = 5;

   private final IRtfListener listener;
   private final Deque events = new ArrayDeque<>();
}