Rust native JSON deserializer

This repository contains a performant Rust implementation to parse JSON by reference.

Why not serde-json?

serde-json is both a JSON parser and data model based on serde's model (Value). Value is an owning data structure.

In many use cases, JSON can be parsed into references. In particular, ownership of strings is only required when the JSON string contains non-ascii characters.

There is a performance oportunity if JSON is parsed by reference instead of by value when possible.

This crate fills this gap. When parsing e.g. a list of strings, this crate is ~2x faster than serde-json (see below).

Safety

This crate is #![forbid(unsafe_code)] and only panics on failed allocations.

Benches

Run

python3 write_bench_files.py && cargo bench --bench parse

for a comparison with serde_json. Broadly speaking, this crate is either faster or equally fast. Some examples:

Array of bools

bool json_deserializer 2^20   time:   [26.067 ms 26.114 ms 26.172 ms]
bool serde_json 2^20    time:   [29.350 ms 29.405 ms 29.459 ms]

Array of strings:

string json_deserializer 2^18 time:   [10.106 ms 10.138 ms 10.173 ms]
string serde_json 2^18  time:   [24.352 ms 24.470 ms 24.616 ms]

Array of an object with a string

object_string json_deserializer 2^14
                        time:   [3.1260 ms 3.1408 ms 3.1588 ms]
object_string serde_json 2^14
                        time:   [4.3516 ms 4.3628 ms 4.3754 ms]

Array of an object with a bool

object_bool json_deserializer 2^10
                        time:   [165.67 us 166.27 us 166.99 us]
object_bool serde_json 2^10
                        time:   [199.96 us 200.71 us 201.56 us]