On Mon, Feb 18, 2013 at 5:03 PM, Christian Henning <chhenning@gmail.com>wrote:
So...doing 2 operator++'s in a row isn't logically equivalent?
Right now, operator++ only sets the _read_scanline flag. So, doing 2 operator++ wont do anything different.
Do have something in mind?
Here is a link to the current version.
http://svn.boost.org/svn/boost/trunk/boost/gil/extension/io/detail/scanline_...
My first reaction is, it doesn't look like the copy constructor will do the right thing (or is it okay to do _reader->clean_up() multiple times?). Secondly, the behavior of operator* and operator++ doesn't read right, but I'm not intimately familiar with what the implementation is suppose to do. Here they are (simplified and reformatted): reference operator*() { if( _read_scanline ) { _reader->read( _buffer, _pos ); } else { _reader->skip( _buffer, _pos ); } ++_pos; _read_scanline = false; return _buffer; } /// Pre-Increment Operator scanline_read_iterator& operator++() { _read_scanline = true; return *this; } So, operator* effectively advances the iterator, while operator++...doesn't? Huh? (Do I have that transcribed correctly?) What I *think* you want is for operator++ to conditionally call _reader->skip (if the previous operator++ had not been followed by a operator*), while operator* should conditionally call _reader->read (depending on if there had been an intervening operator++ after the previous operator*). So, I think you'd need 2 boolean flags. Does that make sense? (I might objectively not be making sense, I'm not sure.) - Jeff