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json v3.1.0 Release Notes

Release Date: 2018-02-01 // about 6 years ago

  • 🚀 Release date: 2018-02-01
    SHA-256: d40f614d10a6e4e4e80dca9463da905285f20e93116c36d97d4dc1aa63d10ba4 (json.hpp), 2b7234fca394d1e27b7e017117ed80b7518fafbb4f4c13a7c069624f6f924673 (include.zip)

    Summary

    This release adds support for the UBJSON format and JSON Merge Patch. It also contains some minor changes and bug fixes. All changes are backward-compatible.

    🍱 ✨ New features

    • The library now supports UBJSON (Universal Binary JSON Specification) as binary format to read and write JSON values space-efficiently. See the documentation overview for a comparison of the different formats CBOR, MessagePack, and UBJSON.
    • 🔀 JSON Merge Patch (RFC 7386) offers an intuitive means to describe patches between JSON values (#876, #877). See the documentation of merge_patch for more information.

    🍱 ⚡️ Improvements

    • The library now uses the Grisu2 algorithm for printing floating-point numbers (based on the reference implementation by Florian Loitsch) which produces a short representation which is guaranteed to round-trip (#360, #935, #936).
    • The UTF-8 handling was further simplified by using the decoder of Björn Hoehrmann in more scenarios.

    🍱 🚚 Reorganization

    • Though the library is released as a single header, its development got more and more complicated. With this release, the header is split into several files and the single-header file json.hpp can be generated from these development sources. In the repository, folder include contains the development sources and single_include contains the single json.hpp header (#700, #906, #907, #910, #911, #915, #920, #924, #925, #928, #944).
    • The split further allowed for a forward declaration header include/nlohmann/json_fwd.hpp to speed up compilation times (#314).

    🍱 🔨 Further changes

    • 👀 Google Benchmark is now used for micro benchmarks (see benchmarks folder, #921).
    • ⚡️ The serialization (JSON and binary formats) now properly work with the libraries string template parameter, allowing for optimized string implementations to be used in constraint environments such as embedded software (#941, #950).
    • The exceptional behavior can now be overridden by defining macros JSON_THROW_USER, JSON_TRY_USER, and JSON_CATCH_USER, defining the behavior of throw, try and catch, respectively. This allows to switch off C++'s exception mechanism yet still execute user-defined code in case an error condition occurs (#938).
    • To facilitate the interplay with flex and Bison, the library does not use the variable name yytext any more as it could clash with macro definitions (#933).
    • The library now defines NLOHMANN_JSON_VERSION_MAJOR, NLOHMANN_JSON_VERSION_MINOR, and NLOHMANN_JSON_VERSION_PATCH to allow for conditional compilation based on the included library version (#943, #948).
    • 🛠 A compilation error with ICC has been fixed (#947).
    • 📚 Typos and links in the documentation have been fixed (#900, #930).
    • 🛠 A compiler error related to incomplete types has been fixed (#919).
    • ✅ The tests form the UTF-8 decoder stress test have been added to the test suite.

    🍱 🔥 Deprecated functions

    • Function iterator_wrapper has been deprecated (#874). Since its introduction, the name was up for discussion, as it was too technical. We now introduced the member function items() with the same semantics. iterator_wrapper will be removed in the next major version (i.e., 4.0.0).

    🚚 Furthermore, the following functions are deprecated since version 3.0.0 and will be removed in the next major version (i.e., 4.0.0):

    Please use friend std::istream& operator>>(std::istream&, basic_json&) and friend operator<<(std::ostream&, const basic_json&) instead.