LuaFFIJson

LuaFFIJson is a Fast JSON parser library written in LUA FFI. It uses LUA FFI to make JSON decoding very fast.

It requires LUA JIT and it's also tested with OpenResty.

JSON decode function is very fast compared to existing LUA/C based JSON decoders.

JSON encode function is comparatively slow because it is written in pure LUA.

It has no other external dependencies.

It is single file library(JsonParser.lua).

It supports UTF-8 and Unicode.

Sample code:

local json = require("JsonParser")
local json_decode = json.decode
local body = [[{
  "en":"I can eat glass and it doesn't hurt me.",
  "zh-Hant":"我能吞下玻璃而不傷身體。",
  "zh-Hans":"我能吞下玻璃而不伤身体。",
  "ja":"私はガラスを食べられます。それは私を傷つけません。",
  "ko":"나는 유리를 먹을 수 있어요. 그래도 아프지 않아요"
}]]
local j = json_decode(body)
print(j)

Output:

{
  en = "I can eat glass and it doesn't hurt me.",
  ja = "私はガラスを食べられます。それは私を傷つけません。",
  ko = "나는 유리를 먹을 수 있어요. 그래도 아프지 않아요",
  ["zh-Hans"] = "我能吞下玻璃而不伤身体。",
  ["zh-Hant"] = "我能吞下玻璃而不傷身體。"
}

Code:

print(j["ko"])

Output:

나는 유리를 먹을 수 있어요. 그래도 아프지 않아요

Code:

local json_encode = json.encode
local s = json.encode(j)
print(s)

Output:

{"en":"I can eat glass and it doesn't hurt me.","zh-Hans":"我能吞下玻璃而不伤身体。","ko":"나는 유리를 먹을 수 있어요. 그래도 아프지 않아요","zh-Hant":"我能吞下玻璃而不傷身體。","ja":"私はガラスを食べられます。それは私を傷つけません。"}

Benchmark (decode):

	JsonParser	cjson	rapidjson
int test	50ms	91ms	55ms
float test	64ms	212ms	59ms
bool test	38ms	69ms	30ms
utf8 test	22ms	14ms	15ms
mixed small test	48ms	60ms	47ms
mixed medium test	133ms	143ms	134ms
large para test	1260ms	823ms	206ms

Test condition:

10000 iteration for each input type with code warmup on my VM machine (2 core) on Mac OS with openresty/1.13.6.1