README.md

Json5 parser for luajit

This crate provides json5 deserialization for luajit.

Inspired and adapted from json5-rs

NOTE: When compiling for macos, please add this to your $CARGO_HOME/config per this article (which also inspired this project):

[target.x86_64-apple-darwin]
rustflags = [
    "-C", "link-arg=-undefined",
    "-C", "link-arg=dynamic_lookup",
]

[target.aarch64-apple-darwin]
rustflags = [
    "-C", "link-arg=-undefined",
    "-C", "link-arg=dynamic_lookup",
]

Also, if you haven't already, add ';?.dylib' to your package.cpath so it will be recognized by the interpreter.

Usage

You can simply require the module in your scripts and parse a string using the parse method:

local parse = require'json5'.parse
local data = [[
{
    /* This is a comment */
    ecma_identifier: 'works like a charm',
    "string keys": [1,2,3], // trailing comma
}
]]
local parsed_data = parse(data)

Use with neovim

You must have cargo installed and in your $PATH

Using packer.nvim:

use {
    'Joakker/lua-json5',
    -- if you're on windows
    -- run = 'powershell ./install.ps1'
    run = './install.sh'
}

Performance

Tested on neovim using the following script:

local data = [[ {"hello":"world"} ]]
local json5 = require('json5').parse
local json_decode = vim.fn.json_decode

local time_json5, time_json_decode = 0, 0

local aux

for _ = 1, 1000 do
    aux = os.clock()
    json5(data)
    time_json5 = time_json5 + (os.clock() - aux)
end

for _ = 1, 1000 do
    aux = os.clock()
    json_decode(data)
    time_json_decode = time_json_decode + (os.clock() - aux)
end

print(('json5:        %.3fms'):format(time_json5))
print(('json_decode:  %.3fms'):format(time_json_decode))

On average:

json5:        0.023ms
json_decode:  0.010ms

So, why should I use this instead of the builtin json_decode?

If performance is your concern, I think you're better off using the builtin function json_decode. The advantage this package has over regular json, however, is that you get json5 features, such as comments, trailing commas and more flexible string literals.