ADD JSON_PARSE

[GillesDuvert]

json_serialize.pro is already written, in src/pro
We need json_parse, ideally with both the /toarray and /tostruct options implemented.
This can be done in IDL language for a start, for a first issue.
But of course a more expert c++ approach using one of the C++ JSON libraries would be a must!

[alaingdl]

What is the status of that ?

[GillesDuvert]

In retrospect, pure IDL/GDL may be uneffective. The demand we had was on huge (>100Mo) JSONs files, so using a c++ json parser is mandatory.

https://json.nlohmann.me/ is the thing we need. I've made some tests. We can exchange externally if you wish.