new specialized branch for constructing ByteBigArrayBigList

[Jeff]

I recently wanted to write a function that used ByteBigArrayBigList if ByteArrayList became too small. I passed what I had so far to a constructor for ByteBigArrayBigList. I discovered that Java used the constructor that accepts a ByteCollection. That's fine, except it uses an iterator. I expected it to use something more efficient like getElements, or for there to be a constructor that accepts a ByteList and does something efficient with the array if it's a ByteArrayList.

Would this be a good change, or unnecessary? I expect similar changes would apply to other types.

Current

public ByteBigArrayBigList(final ByteCollection c) {
   this(Size64.sizeOf(c));
   if (c instanceof ByteBigList) {
     ((ByteBigList)c).getElements(0, a, 0, size = Size64.sizeOf(c));
   } else {
     for (ByteIterator i = c.iterator(); i.hasNext();) add(i.nextByte());
   }
}

expected

public ByteBigArrayBigList(final ByteCollection c) {
  this(Size64.sizeOf(c));
  if (c instanceof ByteBigList) {
    ((ByteBigList) c).getElements(0, a, 0, size = Size64.sizeOf(c));
  } else if (c instanceof ByteArrayList) {

    BigArrays.copy(new byte[][] {((ByteArrayList) c).a}, 0, this.a, 0, size = Size64.sizeOf(c));

  } else {
    for (ByteIterator i = c.iterator(); i.hasNext();) add(i.nextByte());
   }
}

and maybe add

public ByteBigArrayBigList(final ByteList l) {
  this(Size64.sizeOf(l));
  if (l instanceof ByteArrayList) {
    BigArrays.copy(new byte[][] {((ByteArrayList) l).a}, 0, this.a, 0, size = Size64.sizeOf(l));
  } else {
    for(ByteIterator i = l.iterator(); i.hasNext();) add(i.nextByte());
  }
}