chris@1: /*
chris@1:  *   SONEWS News Server
chris@1:  *   see AUTHORS for the list of contributors
chris@1:  *
chris@1:  *   This program is free software: you can redistribute it and/or modify
chris@1:  *   it under the terms of the GNU General Public License as published by
chris@1:  *   the Free Software Foundation, either version 3 of the License, or
chris@1:  *   (at your option) any later version.
chris@1:  *
chris@1:  *   This program is distributed in the hope that it will be useful,
chris@1:  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
chris@1:  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
chris@1:  *   GNU General Public License for more details.
chris@1:  *
chris@1:  *   You should have received a copy of the GNU General Public License
chris@1:  *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
chris@1:  */
chris@1: 
chris@1: package org.sonews.util.io;
chris@1: 
chris@1: import java.io.IOException;
chris@1: import java.io.InputStream;
chris@1: import java.nio.ByteBuffer;
chris@1: import java.nio.charset.Charset;
chris@1: 
chris@1: /**
chris@1:  * InputStream that can change its decoding charset while reading from the
chris@1:  * underlying byte based stream.
chris@1:  * @author Christian Lins
chris@1:  * @since sonews/0.5.0
chris@1:  */
chris@1: public class VarCharsetReader
chris@1: {
chris@1: 
chris@1:   private final ByteBuffer buf = ByteBuffer.allocate(4096);
chris@1:   private InputStream in;
chris@1:   
chris@1:   public VarCharsetReader(final InputStream in)
chris@1:   {
chris@1:     if(in == null)
chris@1:     {
chris@1:       throw new IllegalArgumentException("null InputStream");
chris@1:     }
chris@1:     this.in = in;
chris@1:   }
chris@1:   
chris@1:   /**
chris@1:    * Reads up to the next newline character and returns the line as String.
chris@1:    * The String is decoded using the given charset.
chris@1:    */
chris@1:   public String readLine(Charset charset)
chris@1:     throws IOException
chris@1:   {    
chris@1:     byte[] byteBuf = new byte[1];
chris@1:     String bufStr;
chris@1:     
chris@1:     for(;;)
chris@1:     {
chris@1:       int read = this.in.read(byteBuf);
chris@1:       if(read == 0)
chris@1:       {
chris@1:         continue;
chris@1:       }
chris@1:       else if(read == -1)
chris@1:       {
chris@1:         this.in = null;
chris@1:         bufStr  = new String(this.buf.array(), 0, this.buf.position(), charset);
chris@1:         break;
chris@1:       }
chris@1:       else if(byteBuf[0] == 10) // Is this safe? \n
chris@1:       {
chris@1:         bufStr  = new String(this.buf.array(), 0, this.buf.position(), charset);
chris@1:         break;
chris@1:       }
chris@1:       else if(byteBuf[0] == 13) // \r
chris@1:       { // Skip
chris@1:         continue;
chris@1:       }
chris@1:       else
chris@1:       {
chris@1:         this.buf.put(byteBuf[0]);
chris@1:       }
chris@1:     }
chris@1:     
chris@1:     this.buf.clear();
chris@1:     
chris@1:     return bufStr;
chris@1:   }
chris@1:   
chris@1: }