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/* PIReader.java                                                   NanoXML/Java
 *
 * $Revision: 1.3 $
 * $Date: 2002/01/04 21:03:28 $
 * $Name: RELEASE_2_2_1 $
 *
 * This file is part of NanoXML 2 for Java.
 * Copyright (C) 2000-2002 Marc De Scheemaecker, All Rights Reserved.
 *
 * This software is provided 'as-is', without any express or implied warranty.
 * In no event will the authors be held liable for any damages arising from the
 * use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 *  1. The origin of this software must not be misrepresented; you must not
 *     claim that you wrote the original software. If you use this software in
 *     a product, an acknowledgment in the product documentation would be
 *     appreciated but is not required.
 *
 *  2. Altered source versions must be plainly marked as such, and must not be
 *     misrepresented as being the original software.
 *
 *  3. This notice may not be removed or altered from any source distribution.
 */

package net.n3.nanoxml;


import java.io.Reader;
import java.io.IOException;


/**
 * This reader reads data from another reader until the end of a processing
 * instruction (?>) has been encountered.
 *
 * @author Marc De Scheemaecker
 * @version $Name: RELEASE_2_2_1 $, $Revision: 1.3 $
 */
class PIReader
   extends Reader
{

   /**
    * The encapsulated reader.
    */
   private IXMLReader reader;


   /**
    * True if the end of the stream has been reached.
    */
   private boolean atEndOfData;


   /**
    * Creates the reader.
    *
    * @param reader the encapsulated reader
    */
   PIReader(IXMLReader reader)
   {
      this.reader = reader;
      this.atEndOfData = false;
   }


   /**
    * Cleans up the object when it's destroyed.
    */
   protected void finalize()
      throws Throwable
   {
      this.reader = null;
      super.finalize();
   }


   /**
    * Reads a block of data.
    *
    * @param buffer where to put the read data
    * @param offset first position in buffer to put the data
    * @param size maximum number of chars to read
    *
    * @return the number of chars read, or -1 if at EOF
    *
    * @throws java.io.IOException
    *		if an error occurred reading the data
    */
   public int read(char[] buffer,
                   int    offset,
                   int    size)
      throws IOException
   {
      if (this.atEndOfData) {
         return -1;
      }

      int charsRead = 0;

      if ((offset + size) > buffer.length) {
         size = buffer.length - offset;
      }

      while (charsRead < size) {
         char ch = this.reader.read();

         if (ch == '?') {
            char ch2 = this.reader.read();

            if (ch2 == '>') {
               this.atEndOfData = true;
               break;
            }

            this.reader.unread(ch2);
         }

         buffer[charsRead] = ch;
         charsRead++;
      }

      if (charsRead == 0) {
         charsRead = -1;
      }

      return charsRead;
   }


   /**
    * Skips remaining data and closes the stream.
    *
    * @throws java.io.IOException
    *		if an error occurred reading the data
    */
   public void close()
      throws IOException
   {
      while (! this.atEndOfData) {
         char ch = this.reader.read();

         if (ch == '?') {
            char ch2 = this.reader.read();

            if (ch2 == '>') {
               this.atEndOfData = true;
            }
         }
      }
   }

}