Awesome
Introduction
A high performance JSON library written in ANSI C.
Features
- Fast: can read or write gigabytes per second JSON data on modern CPUs.
- Portable: complies with ANSI C (C89) for cross-platform compatibility.
- Strict: complies with RFC 8259 JSON standard, ensuring strict number format and UTF-8 validation.
- Extendable: offers options to allow comments, trailing commas, NaN/Inf, and custom memory allocator.
- Accuracy: can accurately read and write
int64
,uint64
, anddouble
numbers. - Flexible: supports unlimited JSON nesting levels,
\u0000
characters, and non null-terminated strings. - Manipulation: supports querying and modifying using JSON Pointer, JSON Patch and JSON Merge Patch.
- Developer-Friendly: easy integration with only one
h
and onec
file.
Limitations
- An array or object is stored as a data structure such as linked list, which makes accessing elements by index or key slower than using an iterator.
- Duplicate keys are allowed in an object, and the order of the keys is preserved.
- JSON parsing result is immutable, requiring a
mutable copy
for modification.
Performance
Benchmark project and dataset: yyjson_benchmark
The simdjson's new On Demand
API is faster if most JSON fields are known at compile-time.
This benchmark project only checks the DOM API, a new benchmark will be added later.
AWS EC2 (AMD EPYC 7R32, gcc 9.3)
twitter.json | parse (GB/s) | stringify (GB/s) |
---|---|---|
yyjson(insitu) | 1.80 | 1.51 |
yyjson | 1.72 | 1.42 |
simdjson | 1.52 | 0.61 |
sajson | 1.16 | |
rapidjson(insitu) | 0.77 | |
rapidjson(utf8) | 0.26 | 0.39 |
cjson | 0.32 | 0.17 |
jansson | 0.05 | 0.11 |
iPhone (Apple A14, clang 12)
twitter.json | parse (GB/s) | stringify (GB/s) |
---|---|---|
yyjson(insitu) | 3.51 | 2.41 |
yyjson | 2.39 | 2.01 |
simdjson | 2.19 | 0.80 |
sajson | 1.74 | |
rapidjson(insitu) | 0.75 | |
rapidjson(utf8) | 0.30 | 0.58 |
cjson | 0.48 | 0.33 |
jansson | 0.09 | 0.24 |
More benchmark reports with interactive charts (update 2020-12-12)
Platform | CPU | Compiler | OS | Report |
---|---|---|---|---|
Intel NUC 8i5 | Core i5-8259U | msvc 2019 | Windows 10 2004 | Charts |
Intel NUC 8i5 | Core i5-8259U | clang 10.0 | Ubuntu 20.04 | Charts |
Intel NUC 8i5 | Core i5-8259U | gcc 9.3 | Ubuntu 20.04 | Charts |
AWS EC2 c5a.large | AMD EPYC 7R32 | gcc 9.3 | Ubuntu 20.04 | Charts |
AWS EC2 t4g.medium | Graviton2 (ARM64) | gcc 9.3 | Ubuntu 20.04 | Charts |
Apple iPhone 12 Pro | A14 (ARM64) | clang 12.0 | iOS 14 | Charts |
For better performance, yyjson prefers:
- A modern processor with:
- high instruction level parallelism
- excellent branch predictor
- low penalty for misaligned memory access
- A modern compiler with good optimizer (e.g. clang)
Sample Code
Read JSON string
const char *json = "{\"name\":\"Mash\",\"star\":4,\"hits\":[2,2,1,3]}";
// Read JSON and get root
yyjson_doc *doc = yyjson_read(json, strlen(json), 0);
yyjson_val *root = yyjson_doc_get_root(doc);
// Get root["name"]
yyjson_val *name = yyjson_obj_get(root, "name");
printf("name: %s\n", yyjson_get_str(name));
printf("name length:%d\n", (int)yyjson_get_len(name));
// Get root["star"]
yyjson_val *star = yyjson_obj_get(root, "star");
printf("star: %d\n", (int)yyjson_get_int(star));
// Get root["hits"], iterate over the array
yyjson_val *hits = yyjson_obj_get(root, "hits");
size_t idx, max;
yyjson_val *hit;
yyjson_arr_foreach(hits, idx, max, hit) {
printf("hit%d: %d\n", (int)idx, (int)yyjson_get_int(hit));
}
// Free the doc
yyjson_doc_free(doc);
// All functions accept NULL input, and return NULL on error.
Write JSON string
// Create a mutable doc
yyjson_mut_doc *doc = yyjson_mut_doc_new(NULL);
yyjson_mut_val *root = yyjson_mut_obj(doc);
yyjson_mut_doc_set_root(doc, root);
// Set root["name"] and root["star"]
yyjson_mut_obj_add_str(doc, root, "name", "Mash");
yyjson_mut_obj_add_int(doc, root, "star", 4);
// Set root["hits"] with an array
int hits_arr[] = {2, 2, 1, 3};
yyjson_mut_val *hits = yyjson_mut_arr_with_sint32(doc, hits_arr, 4);
yyjson_mut_obj_add_val(doc, root, "hits", hits);
// To string, minified
const char *json = yyjson_mut_write(doc, 0, NULL);
if (json) {
printf("json: %s\n", json); // {"name":"Mash","star":4,"hits":[2,2,1,3]}
free((void *)json);
}
// Free the doc
yyjson_mut_doc_free(doc);
Read JSON file with options
// Read JSON file, allowing comments and trailing commas
yyjson_read_flag flg = YYJSON_READ_ALLOW_COMMENTS | YYJSON_READ_ALLOW_TRAILING_COMMAS;
yyjson_read_err err;
yyjson_doc *doc = yyjson_read_file("/tmp/config.json", flg, NULL, &err);
// Iterate over the root object
if (doc) {
yyjson_val *obj = yyjson_doc_get_root(doc);
yyjson_obj_iter iter;
yyjson_obj_iter_init(obj, &iter);
yyjson_val *key, *val;
while ((key = yyjson_obj_iter_next(&iter))) {
val = yyjson_obj_iter_get_val(key);
printf("%s: %s\n", yyjson_get_str(key), yyjson_get_type_desc(val));
}
} else {
printf("read error (%u): %s at position: %ld\n", err.code, err.msg, err.pos);
}
// Free the doc
yyjson_doc_free(doc);
Write JSON file with options
// Read the JSON file as a mutable doc
yyjson_doc *idoc = yyjson_read_file("/tmp/config.json", 0, NULL, NULL);
yyjson_mut_doc *doc = yyjson_doc_mut_copy(idoc, NULL);
yyjson_mut_val *obj = yyjson_mut_doc_get_root(doc);
// Remove null values in root object
yyjson_mut_obj_iter iter;
yyjson_mut_obj_iter_init(obj, &iter);
yyjson_mut_val *key, *val;
while ((key = yyjson_mut_obj_iter_next(&iter))) {
val = yyjson_mut_obj_iter_get_val(key);
if (yyjson_mut_is_null(val)) {
yyjson_mut_obj_iter_remove(&iter);
}
}
// Write the json pretty, escape unicode
yyjson_write_flag flg = YYJSON_WRITE_PRETTY | YYJSON_WRITE_ESCAPE_UNICODE;
yyjson_write_err err;
yyjson_mut_write_file("/tmp/config.json", doc, flg, NULL, &err);
if (err.code) {
printf("write error (%u): %s\n", err.code, err.msg);
}
// Free the doc
yyjson_doc_free(idoc);
yyjson_mut_doc_free(doc);
Documentation
The latest (unreleased) documentation can be accessed in the doc directory. The pre-generated Doxygen HTML for the release version can be viewed here:
Packaging status
Built With yyjson
A non-exhaustive list of projects that expose yyjson to other languages or use yyjson internally for a major feature. If you have a project that uses yyjson, feel free to open a PR to add it to this list.
Project | Language | Description |
---|---|---|
py_yyjson | Python | Python bindings for yyjson |
orjson | Python | JSON library for Python with an optional yyjson backend |
cpp-yyjson | C++ | C++ JSON library with a yyjson backend |
reflect-cpp | C++ | C++ library for serialization through automated field name retrieval from structs |
yyjsonr | R | R binding for yyjson |
Ananda | Swift | JSON model decoding based on yyjson |
duckdb | C++ | DuckDB is an in-process SQL OLAP Database Management System |
fastfetch | C | A neofetch-like tool for fetching system information and displaying them in a pretty way |
Zrythm | C | Digital Audio Workstation that uses yyjson to serialize JSON project files |
bemorehuman | C | Recommendation engine with a focus on uniqueness of the person receiving the rec |
mruby-yyjson | mruby | Efficient JSON parsing and serialization library for mruby using yyjson |
TODO for v1.0
- Add documentation page.
- Add GitHub workflow for CI and codecov.
- Add more tests: valgrind, sanitizer, fuzzing.
- Support JSON Pointer to query and modify JSON.
- Add
RAW
type for JSON reader and writer. - Add option to limit real number output precision.
- Add option to support JSON5 (if feasible).
- Add functions to diff two JSON documents.
- Add documentation on performance optimizations.
- Ensure ABI stability.
License
This project is released under the MIT license.