In debug mode generated classes must implement special debug interfaces

[Mingun]

Currently to obtain debug maps with positions you must use reflection. That looks ugly, because you need to catch checked exceptions, that never will be thrown.

I suggest to add to runtime special interfaces, that will be implemented by generated classes when debug mode is activated.

[GreyCat]

I don't quite understand the idea yet — maybe you can go on with some proof of concept code to illustrate how we can avoid reflection?

[Mingun]

public interface PositionInfo {
  Map<String, Integer> attrStart();
  Map<String, Integer> attrEnd();
  Map<String, ? extends List<Integer>> arrStart();
  Map<String, ? extends List<Integer>> arrEnd();
}

final KaitaiStruct struct = …;
// Generator generates classes, that implements this interface,
// if debug mode/positions-info is enabled
if (struct instanceof PositionInfo) {
  final PositionInfo info = (PositionInfo)struct;
  //...
}

[GreyCat]

Sure, this makes sense. Let's do it!

[Mingun]

I'll prepare PR in next couple days, where I also plan to change the way information is stored to solve issue #26. I plan to store both positions -- relative to current IO object and relative to root IO object. This will solve problems with showing incorrect regions in https://github.com/kaitai-io/kaitai_struct_gui (see #26).