sclass DoubleBuffer is Iterable<Double>, IntSize {

  double[] data;

  int size;

  *() {}

  *(int size) { if (size != 0) data = new double[size]; }

  *(Iterable<Double> l) { addAll(l); }

  *(Cl<Double> l) { this(l(l)); addAll(l); }

  *(double... data) { this.data = data; size = l(data); }

  void add(double i) {

    if (size >= lDoubleArray(data)) {

      data = resizeDoubleArray(data, Math.max(1, toInt(Math.min(maximumSafeArraySize(), lDoubleArray(data)*2L))));

      if (size >= data.length) fail("DoubleBuffer too large: " + size);

    }

    data[size++] = i;

  }

  void addAll(Iterable<Double> l) {

    if (l != null) for (double i : l) add(i);

  }

  double[] toArray() {

    ret size == 0 ? null : resizeDoubleArray(data, size);

  }

  double[] toArrayNonNull() {

    ret unnull(toArray());

  }

  L<Double> toList() {

    ret doubleArrayToList(data, 0, size);

  }

  L<Double> asVirtualList() {

    ret new RandomAccessAbstractList<Double> {

      public int size() { ret size; }

      public Double get(int i) { ret DoubleBuffer.this.get(i); }

      public Double set(int i, Double val) {

        Double a = get(i);

        data[i] = val;

        ret a;

      }

    };

  }

  void reset { size = 0; }

  void clear { reset(); }

  public int size() { ret size; }

  double get(int idx) {

    if (idx >= size) fail("Index out of range: " + idx + "/" + size);

    ret data[idx];

  }

  void set(int idx, double value) {

    if (idx >= size) fail("Index out of range: " + idx + "/" + size);

    data[idx] = value;

  }

  double popLast() {

    if (size == 0) fail("empty buffer");

    ret data[--size];

  }

  double last() { ret data[size-1]; }

  double nextToLast() { ret data[size-2]; }

  toString { ret squareBracket(joinWithSpace(toList())); }

  public Iterator<Double> iterator() {

    ret new ItIt<Double> {

      int i = 0;

      public bool hasNext() { ret i < size; }

      public Double next() {

        //if (!hasNext()) fail("Index out of bounds: " + i);

        ret data[i++];

      }

    };

  }

  /*public DoubleIterator doubleIterator() {

    ret new DoubleIterator {

      int i = 0;

      public bool hasNext() { ret i < size; }

      public int next() {

        //if (!hasNext()) fail("Index out of bounds: " + i);

        ret data[i++];

      }

      toString { ret "Iterator@" + i + " over " + DoubleBuffer.this; }

    };

  }*/

  void trimToSize {

    data = resizeDoubleArray(data, size);

  }

  int indexOf(double b) {

    for i to size:

      if (data[i] == b)

        ret i;

    ret -1;

  }

  double[] subArray(int start, int end) {

    ret subDoubleArray(data, start, min(end, size));

  }

}