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Boost.JSON
Overview
Boost.JSON is a portable C++ library which provides containers and algorithms that implement JavaScript Object Notation, or simply "JSON", a lightweight data-interchange format. This format is easy for humans to read and write, and easy for machines to parse and generate. It is based on a subset of the JavaScript Programming Language (Standard ECMA-262), and is currently standardised in RFC 8259. JSON is a text format that is language-independent but uses conventions that are familiar to programmers of the C-family of languages, including C, C++, C#, Java, JavaScript, Perl, Python, and many others. These properties make JSON an ideal data-interchange language.
This library focuses on a common and popular use-case: parsing
and serializing to and from a container called value which
holds JSON types. Any value which you build can be serialized
and then deserialized, guaranteeing that the result will be equal
to the original value. Whatever JSON output you produce with this
library will be readable by most common JSON implementations
in any language.
The value container is designed to be well suited as a
vocabulary type appropriate for use in public interfaces and
libraries, allowing them to be composed. The library restricts
the representable data types to the ranges which are almost
universally accepted by most JSON implementations, especially
JavaScript. The parser and serializer are both highly performant,
meeting or exceeding the benchmark performance of the best comparable
libraries. Allocators are very well supported. Code which uses these
types will be easy to understand, flexible, and performant.
Boost.JSON offers these features:
- Fast compilation
- Require only C++11
- Fast streaming parser and serializer
- Constant-time key lookup for objects
- Options to allow non-standard JSON
- Easy and safe modern API with allocator support
- Optional header-only, without linking to a library
Visit https://boost.org/libs/json for complete documentation.
Requirements
- Requires only C++11
- Link to a built static or dynamic Boost library, or use header-only (see below)
- Supports -fno-exceptions, detected automatically
The library relies heavily on these well known C++ types in its interfaces (henceforth termed standard types):
string_viewmemory_resource,polymorphic_allocatorerror_category,error_code,error_condition,system_error
Header-Only
To use as header-only; that is, to eliminate the requirement to link a program to a static or dynamic Boost.JSON library, simply place the following line in exactly one new or existing source file in your project.
#include <boost/json/src.hpp>
MSVC users must also define the macro BOOST_JSON_NO_LIB to disable
auto-linking. Note, that if you also want to avoid linking to Boost.Container,
which is a dependency of Boost.JSON, you have to define
BOOST_CONTAINER_NO_LIB. In order to disable auto-linking to Boost libraries
completely you can define BOOST_ALL_NO_LIB instead.
Embedded
Boost.JSON works great on embedded devices. The library uses local stack buffers to increase the performance of some operations. On Intel platforms these buffers are large (4KB), while on non-Intel platforms they are small (256 bytes). To adjust the size of the stack buffers for embedded applications define this macro when building the library or including the function definitions:
#define BOOST_JSON_STACK_BUFFER_SIZE 1024
#include <boost/json/src.hpp>
Endianness
Boost.JSON uses Boost.Endian in order to support both little endian and big endian platforms.
Supported Compilers
Boost.JSON has been tested with the following compilers:
- clang: 3.5, 3.6, 3.7, 3.8, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14
- gcc: 4.8, 4.9, 5, 6, 7, 8, 9, 10, 11, 12
- msvc: 14.0, 14.1, 14.2, 14.3
Note: support for GCC 4.8 and 4.9 is deprecated and will stop in Boost 1.88.0.
Supported JSON Text
The library expects input text to be encoded using UTF-8, which is a requirement put on all JSON exchanged between systems by the RFC. Similarly, the text generated by the library is valid UTF-8.
The RFC does not allow byte order marks (BOM) to appear in JSON text, so the library considers BOM syntax errors.
The library supports several popular JSON extensions. These have to be explicitly enabled.
Visual Studio Solution
cmake -G "Visual Studio 16 2019" -A Win32 -B bin -DCMAKE_TOOLCHAIN_FILE=cmake/toolchains/msvc.cmake
cmake -G "Visual Studio 16 2019" -A x64 -B bin64 -DCMAKE_TOOLCHAIN_FILE=cmake/toolchains/msvc.cmake
Quality Assurance
The development infrastructure for the library includes these per-commit analyses:
- Coverage reports
- Benchmark performance comparisons
- Compilation and tests on Drone.io, Azure Pipelines, Appveyor
- Fuzzing using clang-llvm and machine learning
License
Distributed under the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at https://www.boost.org/LICENSE_1_0.txt)