A complete rewrite of the string escape function. It now provides codepoint-to-\uxxxx escaping. Invalid UTF-8 byte sequences are not escaped, but copied as-is. I haven’t spent much time optimizing the code - but the library now agrees with Python on every single Unicode character’s escaping (see file test/data/json_nlohmann_tests/all_unicode_ascii.json).
Other minor changes: replaced "size_t" by "std::size_t"
An optional parameter for dump() allows to set the character to use for
indentation (default: space). In case a JSON value is serialized to an
output stream, its fill character is used (and can be set with
std::setfill).
A lot of small changes to avoid memory allocations:
- The locale is only queried once rather than with every number
serialization.
- The indentation string is recycled between different calls.
- The string escape function avoids a copy if no escaping is necessary.
- The string escape and the space function use a complete switch case
instead of cascaded ifs.
Cachegrind measures some 15% performance improvement.
The class is currently just a wrapper for an std::ostream and collects
all functions related to serialization. The next step should be
recycling of variables to avoid repetitive initialization for each
recursive dump call.
