Niels Lohmann 209348c151 Escape runs of multi-byte characters straight into the write buffer ...

With ensure_ascii, every non-ASCII character went through the UTF-8
state machine one byte at a time and its \uXXXX escape was assembled in
string_buffer and copied to the write buffer afterwards.

A run of well-formed multi-byte characters is now decoded and escaped
directly into the write buffer. The first byte that is ASCII or starts an
ill-formed or truncated sequence ends the run and is left to the
unchanged byte-at-a-time path, so error handling and its messages
(positions, replacement, ignore, keep) are as before.

Apple M1, Apple clang, retired instructions per dump(-1, ' ', true):
  cjk text      15.9M -> 6.94M (-56 %)   twitter 9.10M -> 6.16M (-32 %)
  emoji text    8.89M -> 6.08M (-32 %)   latin text 10.3M -> 9.23M (-10 %)
Pure ASCII documents with escapes (logs, JSON in JSON) and all modes
without ensure_ascii are unchanged.

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

2026-10-22 09:28:16 +02:00

..

json_fwd.hpp

Scan strings with SSE2, SSSE3, or NEON (#5853)

2026-10-21 20:00:50 +02:00

json_literals.hpp

Move the user-defined string literals to <nlohmann/json_literals.hpp> and add JSON_NO_AUTOMATIC_UDLS (#5610)

2026-09-30 20:08:17 +02:00

json_view.hpp

Use standard library helpers where available, with C++11 fallbacks (#5876)

2026-10-21 20:14:59 +02:00

json.hpp

Escape runs of multi-byte characters straight into the write buffer

2026-10-22 09:28:16 +02:00