yyjson 0.8.0
A high performance C JSON library.
Building and testing

There are several ways to integrate this library into your project: source code, package manager, and CMake.

Source code

This library aims to provide a cross-platform JSON library, so it is written in ANSI C (actually C99, but compatible with strict C89). You can copy yyjson.h and yyjson.c to your project and start using it without any configuration.

The library has been tested with gcc, clang, msvc, tcc compilers and x86, arm, ppc, riscv, s390x architectures in Github CI. Please report a bug if you encounter any compilation issues.

The library has all features enabled by default, but you can trim out some of them by adding compile-time options. For example, you can disable the JSON writer to reduce the binary size when you don't need serialization, or disable comments support to improve parsing performance. See Compile-time Options for details.

Package manager

You can use some popular package managers like vcpkg, conan, and xmake to download and install yyjson. The yyjson package in these package managers is kept up to date by community contributors. If the version is out of date, please create an issue or pull request on their repository.

Use vcpkg

You can build and install yyjson using vcpkg dependency manager:

git clone https://github.com/Microsoft/vcpkg.git
cd vcpkg
./bootstrap-vcpkg.sh # ./bootstrap-vcpkg.bat for Powershell
./vcpkg integrate install
./vcpkg install yyjson

If the version is out of date, please create an issue or pull request on the vcpkg repository.

CMake

Use CMake to build a library

Clone the repository and create build directory:

git clone https://github.com/ibireme/yyjson.git
mkdir build
cd build

Build static library:

cmake ..
cmake --build .

Build shared library:

cmake .. -DBUILD_SHARED_LIBS=ON
cmake --build .

Supported CMake options:

  • -DYYJSON_BUILD_TESTS=ON Build all tests.
  • -DYYJSON_BUILD_FUZZER=ON Build fuzzer with LibFuzzing.
  • -DYYJSON_BUILD_MISC=ON Build misc.
  • -DYYJSON_BUILD_DOC=ON Build documentation with doxygen.
  • -DYYJSON_ENABLE_COVERAGE=ON Enable code coverage for tests.
  • -DYYJSON_ENABLE_VALGRIND=ON Enable valgrind memory checker for tests.
  • -DYYJSON_ENABLE_SANITIZE=ON Enable sanitizer for tests.
  • -DYYJSON_ENABLE_FASTMATH=ON Enable fast-math for tests.
  • -DYYJSON_FORCE_32_BIT=ON Force 32-bit for tests (gcc/clang/icc).
  • -DYYJSON_DISABLE_READER=ON Disable JSON reader if you don't need it.
  • -DYYJSON_DISABLE_WRITER=ON Disable JSON writer if you don't need it.
  • -DYYJSON_DISABLE_UTILS=ON Disable JSON Pointer, JSON Patch and JSON Merge Patch.
  • -DYYJSON_DISABLE_FAST_FP_CONV=ON Disable builtin fast floating-pointer conversion.
  • -DYYJSON_DISABLE_NON_STANDARD=ON Disable non-standard JSON support at compile-time.
  • -DYYJSON_DISABLE_UTF8_VALIDATION=ON Disable UTF-8 validation at compile-time.
  • -DYYJSON_DISABLE_UNALIGNED_MEMORY_ACCESS=ON Disable unaligned memory access support at compile-time.

Use CMake as a dependency

You can download and unzip yyjson to your project directory and link it in your CMakeLists.txt file:

# Add some options (optional)
set(YYJSON_DISABLE_NON_STANDARD ON CACHE INTERNAL "")
# Add the `yyjson` subdirectory
add_subdirectory(vendor/yyjson)
# Link yyjson to your target
target_link_libraries(your_target PRIVATE yyjson)

If your CMake version is higher than 3.11, you can use the following code to let CMake automatically download it:

include(FetchContent)
# Let CMake download yyjson
FetchContent_Declare(
yyjson
GIT_REPOSITORY https://github.com/ibireme/yyjson.git
GIT_TAG master # master, or version number, e.g. 0.6.0
)
FetchContent_GetProperties(yyjson)
if(NOT yyjson_POPULATED)
FetchContent_Populate(yyjson)
add_subdirectory(${yyjson_SOURCE_DIR} ${yyjson_BINARY_DIR} EXCLUDE_FROM_ALL)
endif()
# Link yyjson to your target
target_link_libraries(your_target PRIVATE yyjson)

Use CMake to generate project

If you want to build or debug yyjson with another compiler or IDE, try these commands:

# Clang for Linux/Unix:
cmake .. -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
# Intel ICC for Linux/Unix:
cmake .. -DCMAKE_C_COMPILER=icc -DCMAKE_CXX_COMPILER=icpc
# Other version of GCC:
cmake .. -DCMAKE_C_COMPILER=/usr/local/gcc-8.2/bin/gcc -DCMAKE_CXX_COMPILER=/usr/local/gcc-8.2/bin/g++
# Microsoft Visual Studio for Windows:
cmake .. -G "Visual Studio 16 2019" -A x64
cmake .. -G "Visual Studio 16 2019" -A Win32
cmake .. -G "Visual Studio 15 2017 Win64"
# Xcode for macOS:
cmake .. -G Xcode
# Xcode for iOS:
cmake .. -G Xcode -DCMAKE_SYSTEM_NAME=iOS
# Xcode with XCTest
cmake .. -G Xcode -DYYJSON_BUILD_TESTS=ON

Use CMake to generate documentation

This library uses doxygen to generate the documentation, (make sure you have doxygen installed before proceeding):

cmake .. -DYYJSON_BUILD_DOC=ON
cmake --build .

After executing this script, doxygen will generate HTML files, which can be found in build/doxygen/html. You can also access the pre-generated document online at: https://ibireme.github.io/yyjson/doc/doxygen/html/

Testing With CMake and CTest

Build and run all tests:

cmake .. -DYYJSON_BUILD_TESTS=ON
cmake --build .
ctest --output-on-failure

Build and run tests with valgrind memory checker, (make sure you have valgrind installed before proceeding):

cmake .. -DYYJSON_BUILD_TESTS=ON -DYYJSON_ENABLE_VALGRIND=ON
cmake --build .
ctest --output-on-failure

Build and run tests with sanitizer (compiler should be gcc or clang):

cmake .. -DYYJSON_BUILD_TESTS=ON -DYYJSON_ENABLE_SANITIZE=ON
cmake --build .
ctest --output-on-failure

Build and run code coverage with gcc:

cmake .. -DCMAKE_BUILD_TYPE=Debug -DYYJSON_BUILD_TESTS=ON -DYYJSON_ENABLE_COVERAGE=ON
cmake --build . --config Debug
ctest --output-on-failure
lcov -c -d ./CMakeFiles --include "*/yyjson.*" -o cov.info
genhtml cov.info -o ./cov_report

Build and run code coverage with clang:

cmake .. -DCMAKE_BUILD_TYPE=Debug -DYYJSON_BUILD_TESTS=ON -DYYJSON_ENABLE_COVERAGE=ON -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
cmake --build . --config Debug
export LLVM_PROFILE_FILE=cov/profile-%p.profraw
ctest --output-on-failure
ctest_files=$(grep -o "test_\w\+ " CTestTestfile.cmake | uniq | tr '\n' ' ')
ctest_files=$(echo $ctest_files | sed 's/ $//' | sed "s/ / -object /g")
llvm-profdata merge -sparse cov/profile-*.profraw -o coverage.profdata
llvm-cov show $ctest_files -instr-profile=coverage.profdata -format=html > coverage.html

Build and run fuzz test with LibFuzzer (compiler should be LLVM Clang, while Apple Clang or gcc are not supported):

cmake .. -DYYJSON_BUILD_FUZZER=ON -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++
cmake --build .
./fuzzer -dict=fuzzer.dict ./corpus

Compile-time Options

This library provides various compile-time options that can be defined as 1 to disable specific features during compilation.

YYJSON_DISABLE_READER
Define this as 1 to disable the JSON reader.
This will disable these functions at compile-time:

yyjson_api yyjson_doc * yyjson_read_file(const char *path, yyjson_read_flag flg, const yyjson_alc *alc, yyjson_read_err *err)
yyjson_api yyjson_doc * yyjson_read_opts(char *dat, size_t len, yyjson_read_flag flg, const yyjson_alc *alc, yyjson_read_err *err)
yyjson_api_inline yyjson_doc * yyjson_read(const char *dat, size_t len, yyjson_read_flag flg)
Definition: yyjson.h:936

This will reduce the binary size by about 60%.
It is recommended when JSON parsing is not required.

YYJSON_DISABLE_WRITER
Define this as 1 to disable JSON writer.
This will disable these functions at compile-time:

yyjson_api_inline char * yyjson_val_write(const yyjson_val *val, yyjson_write_flag flg, size_t *len)
Definition: yyjson.h:1444
yyjson_api bool yyjson_write_file(const char *path, const yyjson_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api char * yyjson_write_opts(const yyjson_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, size_t *len, yyjson_write_err *err)
yyjson_api_inline char * yyjson_mut_val_write(const yyjson_mut_val *val, yyjson_write_flag flg, size_t *len)
Definition: yyjson.h:1546
yyjson_api bool yyjson_val_write_file(const char *path, const yyjson_val *val, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api char * yyjson_val_write_opts(const yyjson_val *val, yyjson_write_flag flg, const yyjson_alc *alc, size_t *len, yyjson_write_err *err)
yyjson_api char * yyjson_mut_write_opts(const yyjson_mut_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, size_t *len, yyjson_write_err *err)
yyjson_api_inline char * yyjson_mut_write(const yyjson_mut_doc *doc, yyjson_write_flag flg, size_t *len)
Definition: yyjson.h:1339
yyjson_api char * yyjson_mut_val_write_opts(const yyjson_mut_val *val, yyjson_write_flag flg, const yyjson_alc *alc, size_t *len, yyjson_write_err *err)
yyjson_api_inline char * yyjson_write(const yyjson_doc *doc, yyjson_write_flag flg, size_t *len)
Definition: yyjson.h:1235
yyjson_api bool yyjson_mut_write_file(const char *path, const yyjson_mut_doc *doc, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)
yyjson_api bool yyjson_mut_val_write_file(const char *path, const yyjson_mut_val *val, yyjson_write_flag flg, const yyjson_alc *alc, yyjson_write_err *err)

This will reduce the binary size by about 30%.
It is recommended when JSON serialization is not required.

YYJSON_DISABLE_UTILS
Define this as 1 to disable JSON Pointer, JSON Patch and JSON Merge Patch supports.

This will disable these functions at compile-time:

yyjson_ptr_xxx()
yyjson_mut_ptr_xxx()
yyjson_doc_ptr_xxx()
yyjson_mut_doc_ptr_xxx()
yyjson_api yyjson_mut_val * yyjson_patch(yyjson_mut_doc *doc, yyjson_val *orig, yyjson_val *patch, yyjson_patch_err *err)
yyjson_api yyjson_mut_val * yyjson_merge_patch(yyjson_mut_doc *doc, yyjson_val *orig, yyjson_val *patch)
yyjson_api yyjson_mut_val * yyjson_mut_merge_patch(yyjson_mut_doc *doc, yyjson_mut_val *orig, yyjson_mut_val *patch)
yyjson_api yyjson_mut_val * yyjson_mut_patch(yyjson_mut_doc *doc, yyjson_mut_val *orig, yyjson_mut_val *patch, yyjson_patch_err *err)

It is recommended when these functions are not required.

YYJSON_DISABLE_FAST_FP_CONV
Define this as 1 to disable the fast floating-point number conversion in yyjson, and use libc's strtod/snprintf instead.
This will reduce binary size by about 30%, but significantly slows down the floating-point read/write speed.
It is recommended when dealing with JSON that contains a minimal number of floating-point numbers.

YYJSON_DISABLE_NON_STANDARD
Define this as 1 to disable non-standard JSON support at compile-time:

  • Reading and writing inf/nan literal, such as NaN, -Infinity.
  • Single line and multiple line comments.
  • Single trailing comma at the end of an object or array.
  • Invalid unicode in string value.

This will also invalidate these run-time options:

static const yyjson_read_flag YYJSON_READ_ALLOW_TRAILING_COMMAS
Definition: yyjson.h:758
static const yyjson_write_flag YYJSON_WRITE_ALLOW_INF_AND_NAN
Definition: yyjson.h:1082
static const yyjson_read_flag YYJSON_READ_ALLOW_INF_AND_NAN
Definition: yyjson.h:765
static const yyjson_read_flag YYJSON_READ_ALLOW_INVALID_UNICODE
Definition: yyjson.h:779
static const yyjson_write_flag YYJSON_WRITE_ALLOW_INVALID_UNICODE
Definition: yyjson.h:1093
static const yyjson_read_flag YYJSON_READ_ALLOW_COMMENTS
Definition: yyjson.h:761

This will reduce binary size by about 10%, and slightly improves performance.
It is recommended when not dealing with non-standard JSON.

YYJSON_DISABLE_UTF8_VALIDATION
Define as 1 to disable UTF-8 validation at compile time.

If all input strings are guaranteed to be valid UTF-8 encoding (for example, some language's String object has already validated the encoding), using this flag can avoid redundant UTF-8 validation in yyjson.

This flag can speed up the reading and writing speed of non-ASCII encoded strings by about 3% to 7%.

Note: If this flag is used while passing in illegal UTF-8 strings, the following errors may occur:

  • Escaped characters are ignored when parsing JSON strings.
  • Ending quotes are ignored when parsing JSON strings, causing the string to be concatenated to the next value.
  • When accessing yyjson_mut_val for serialization, the string ending is accessed out of bounds, causing a segmentation fault.

YYJSON_EXPORTS
Define this as 1 to export symbols when building the library as a Windows DLL.

YYJSON_IMPORTS
Define this as 1 to import symbols when using the library as a Windows DLL.