Niels Lohmann 5f2d976129 Flatten into a std::map by inserting next to the previous entry ...

flatten() added every path with operator[], so each insertion into the
std::map of the result searched the tree from the root and compared long
shared path prefixes, which took half the time on canada.json. Paths come
out in nearly sorted order, so they are now inserted with emplace_hint
next to the entry added last, for object types that have it. ordered_map
keeps its append without lookup, and other object types keep
operator[].

Path segments are also appended in place, without a temporary string
for each escaped key or array index.

flatten() of canada.json, citm_catalog.json and twitter.json is 1.4x to
1.9x as fast; ordered_json is unchanged (1.05x). The output is
unchanged.

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

2026-10-16 19:37:46 +02:00

..

nlohmann

Flatten into a std::map by inserting next to the previous entry

2026-10-16 19:37:46 +02:00