Niels Lohmann b98aef8a07 Round-trip BJData ND-array annotations exactly (single precision, key order) ...

to_bjdata() encoded a JData-annotated object as a BJData ND-array in two
cases where from_bjdata() then returned a different value, breaking the
documented round-trip guarantee:

1. A "single" element that is finite and in range but not exactly
   representable as float (e.g. 0.1) or that underflows to 0 (e.g. 1e-300)
   was silently narrowed instead of falling back to a plain object, unlike
   out-of-range integer elements. write_bjdata_ndarray() now only accepts a
   "single" element if it survives the narrowing to float and back, the
   same criterion write_compact_float() already uses for CBOR/MessagePack.

2. from_bjdata() emitted the annotation keys as _ArraySize_, _ArrayType_,
   _ArrayData_ instead of the documented _ArrayType_, _ArraySize_,
   _ArrayData_, because the size key is written while the dimension vector
   is read, before the type key. For ordered_json, whose comparison takes
   key order into account, this made a round trip of the documented example
   compare unequal. The element type marker is known before the dimension
   vector is read (it precedes '#'), so it is now passed down and the
   "_ArrayType_" key is emitted first.

Fixes #5661.

Signed-off-by: Niels Lohmann <mail@nlohmann.me>

2026-09-29 23:52:49 +02:00

..

nlohmann

Round-trip BJData ND-array annotations exactly (single precision, key order)

2026-09-29 23:52:49 +02:00