// InputStream you can cut off at a certain byte
// (to test streaming input)
sclass SimulatedPartialInputStream extends InputStreamPlusReadFully {
  InputStream in;
  bool streamEnded;
  long position, cutOffPoint, mark;
  
  *(InputStream *in) {}
  
  public int read() throws IOException {
    if (streamEnded || streamPaused()) ret -1;
    int b = in.read();
    if (b >= 0) ++position;
    else set streamEnded;
    ret b;
  }
  
  public void setCutOffPoint(long point) {
    cutOffPoint = point;
  }
  
  public bool streamPaused() { ret position >= cutOffPoint; }
  public bool streamEnded() { ret streamEnded; }
  
  public void incCutOffPoint(long bytes) {
    cutOffPoint += bytes;
  }
  
  @Override public bool markSupported() { true; }
  
  @Override public void mark(int readLimit) {
    mark = position;
    in.mark(readLimit);
  }
  
  @Override public void reset() throws IOException {
    if (mark < 0) fail();
    position = mark;
    mark = -1;
    in.reset();
  }
  
  toString { ret renderVars SimulatedPartialInputStream(+streamEnded, +position, +cutOffPoint, +mark); }
}