[Cbor] Dealing with -0.0, NaN, and Infinity

[Anders Rundgren <[e-mail]>]

When trying to define a subset of CBOR CDE suitable as a JSON replacement
https://github.com/wintercg/admin/issues/69
I ran into a few issues with floating point numbers.

Although -0.0, NaN, and Infinity probably have very limited relevance in the intended target market, they must still be dealt with in some way.  The easy way is of course to just ban them during decoding.  FWIW, these are my current suggestions:

Following IEEE 754 rules it seems that -0.0 does not interfere with normal operations including comparisons; it is still treated as 0.0. So it is currently supported "as is".

However, since mathematical operations using NaN and Infinity are somewhat less nice, and typically indicate that something is fundamentally wrong, their support is currently made optional: https://cyberphone.github.io/CBOR.js/doc/#decoder.cbor.initextended

NaN with payloads are always rejected.  It is still a "strict subset" :)

Related: since the JavaScript "JSON" object never became compatible with Open API number requirements, this became a core priority for "CBOR": https://cyberphone.github.io/CBOR.js/doc/#cbor.int.getint64


WDYT?

Anders