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Java library to create Telegram Clients
There is a newer version: 66.2
/*
 * Created on 3 jul 2009
 */

package jawnae.pyronet;

import org.telegram.mtproto.transport.BuffersStorage;
import org.telegram.mtproto.transport.ByteBufferDesc;

import java.nio.ByteBuffer;
import java.util.ArrayList;
import java.util.List;

public class ByteStream {
   private final List queue;

   public ByteStream() {
      // the queue is expected to be relatively small, and iterated often.
      // hence removing the first element will be fast, even when using an ArrayList
      this.queue = new ArrayList<>();
   }

   /**
    * Appends the ByteBuffer instance to the ByteStream. The
    * bytes are not copied, so do not modify the contents of
    * the ByteBuffer.
    */

   public void append(ByteBufferDesc buf) {
      if (buf == null) {
         throw new NullPointerException();
      }
      this.queue.add(buf);
   }

   /**
    * Returns whether there are any bytes pending in this stream
    */

   public boolean hasData() {
      final int size = this.queue.size();
      for (ByteBufferDesc aQueue : this.queue) {
         if (aQueue.hasRemaining()) {
            return true;
         }
      }
      return false;
   }

   /**
    * Fills the specified buffer with as much bytes as
    * possible. When N bytes are read, the buffer position
    * will be increased by N
    */

   public void get(ByteBuffer dst) {
      if (dst == null) {
         throw new NullPointerException();
      }

      for (ByteBufferDesc bufferDesc : this.queue) {
         ByteBuffer data = bufferDesc.buffer.slice();

         if (data.remaining() > dst.remaining()) {
            data.limit(dst.remaining());
            dst.put(data);
            break;
         }

         dst.put(data);

         if (!dst.hasRemaining()) {
            break;
         }
      }
   }

   /**
    * Discards the specified amount of bytes from the stream.
    *
    * @throws PyroException if it failed to discard the
    *                       specified number of bytes
    */

   public void discard(int count) {
      int original = count;

      while (count > 0) {
         ByteBufferDesc data = this.queue.get(0);

         if (count < data.buffer.remaining()) {
            data.position(data.position() + count);
            count = 0;
            break;
         }

         this.queue.remove(0);
         BuffersStorage.getInstance().reuseFreeBuffer(data);
         count -= data.buffer.remaining();
      }

      if (count != 0) {
         throw new PyroException("discarded " + (original - count) + "/" + original + " bytes");
      }
   }
}