amorfo77/json
1
0
Fork 0
mirror of https://github.com/nlohmann/json.git synced 2026-10-04 05:30:31 +00:00
Code Issues Packages Projects Releases Wiki Activity

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

Browse Source 
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>
This commit is contained in:
Niels Lohmann
2026-09-29 23:52:49 +02:00
parent 633de8e44b
commit b98aef8a07
5 changed files with 162 additions and 52 deletions
Download Patch File Download Diff File Expand all files Collapse all files
include/nlohmann/detail/output/binary_writer.hpp
+14 -2
View File
@@ -1991,9 +1991,21 @@ class binary_writer
case 'd':
{
const auto dval = el.template get<double>();
in_range = !std::isfinite(dval) ||
#ifdef __GNUC__
JSON_HEDLEY_DIAGNOSTIC_PUSH
JSON_HEDLEY_PRAGMA(GCC diagnostic ignored "-Wfloat-equal")
#endif
// a value that would be rounded (rather than exactly represented) by the
// narrowing to float is treated like an out-of-range integer element above;
// this is the same criterion write_compact_float() uses for CBOR/MessagePack
in_range = std::isnan(dval) ||
(dval >= static_cast<double>(std::numeric_limits<float>::lowest()) &&
dval <= static_cast<double>((std::numeric_limits<float>::max)()));
dval <= static_cast<double>((std::numeric_limits<float>::max)()) &&
static_cast<double>(static_cast<float>(dval)) == dval) ||
std::isinf(dval);
#ifdef __GNUC__
JSON_HEDLEY_DIAGNOSTIC_POP
#endif
break;
}
default: