Custom input adapter

[asraa]

Hi!

The open source project I work on is working on migrating away from RapidJSON to this nlohmann/json. To get function parity, I need to be a custom input adapter to track line numbers by counting newline characters. (In case there is an error in parsing, we can print out "error at line number blah" on the JSON string, and the custom object build on SAX parsing has references to line numbers).

However, I'm struggling to see how I can implement a custom input adapter to pass into sax_parse, without running into a failure that there is no matching constructor for input_adapter here

json/include/nlohmann/json.hpp

Line 6813 in d8d8cbf

auto ia = detail::input_adapter(std::forward<InputType>(i));

.

Ideally, I would like to subclass iterator_input_adapter, override get_character() to also track how many newline characters are seen, and pass this custom input adapter to sax_parse.

I have read through #834, and don't see a resolution here. Maybe there is a better way to achieve what I need?

Thank you!