sclass ByteArraysPartialInputStream extends InputStream {
  sclass State {
    int ofs;
    MinimalChain<byte[]> chain;
    
    *(int *ofs, MinimalChain<byte[]> *chain) {}
  }
  
  bool eof;
  MinimalChain<byte[]> last = new MinimalChain(null);
  State state = new(0, last);
  long absolutePosition;
  State mark;
  long markPosition;

  public synchronized int read() throws IOException {
    while ping (true) {
      if (state.ofs < l(state.chain)) {
        ++absolutePosition;
        ret state.chain![state.ofs++];
      }
    
      if (state.chain.next == null)
        ret -1;
      
      state = new State(0, state.chain.next);
    }
  }
  
  public synchronized void add(byte[] buffer) {
    last.setNext(new MinimalChain(null));
    last.setElement(buffer);
    last = last.next;
  }
  
  public void addEOF() {
    eof = true;
  }
  
  public bool isEOF() {
    ret state.chain == last && eof;
  }
  
  @Override public bool markSupported() { true; }
  
  @Override public void mark(int readLimit) {
    mark = new State(state.ofs, state.chain);
    markPosition = absolutePosition;
  }
  
  @Override public void reset() throws IOException {
    if (mark != null) fail();
    state = mark;
    absolutePosition = markPosition;
    mark = null;
    markPosition = 0;
  }
}