go-lua

A Lua 5.4 VM in pure Go — no CGo, no dependencies.

This is a fork of Shopify/go-lua, upgraded from Lua 5.3 to Lua 5.4.

What's new compared to Shopify/go-lua?

• Native 64-bit integers (int64) alongside floats (float64)
• Bitwise operators: &, |, ~, <<, >> and unary ~
• Integer division: //
• Coroutines: coroutine.create, resume, yield, wrap, status, running, close, isyieldable
• UTF-8 library: utf8.char, utf8.codes, utf8.codepoint, utf8.len, utf8.offset
• String packing: string.pack, string.unpack, string.packsize
• String dump: string.dump (with strip option)
• Math extensions: math.tointeger, math.type, math.ult, math.maxinteger, math.mininteger
• Table move: table.move(a1, f, e, t [,a2])
• Table metamethods: table.insert, table.remove, table.sort respect __index/__newindex
• Hex float format: string.format supports %a/%A
• To-be-closed variables: <close> attribute and __close metamethod
• Const variables: <const> attribute
• Generalized for with to-be-closed control variable
• warn() function
• Debug library: debug.getlocal, debug.setlocal, debug.getinfo, debug.sethook (including coroutine hooks)

Getting started

go get github.com/speedata/go-lua

A minimal example:

package main

import "github.com/speedata/go-lua"

func main() {
    l := lua.NewState()
    lua.OpenLibraries(l)
    if err := lua.DoFile(l, "hello.lua"); err != nil {
        panic(err)
    }
}

Calling Lua from Go

l := lua.NewState()
lua.OpenLibraries(l)

lua.DoString(l, `
    function greet(name)
        return "Hello, " .. name .. "!"
    end
`)

l.Global("greet")
l.PushString("World")
l.Call(1, 1)
result, _ := l.ToString(-1)
fmt.Println(result) // Hello, World!

Registering Go functions in Lua

l := lua.NewState()
lua.OpenLibraries(l)

l.Register("add", func(l *lua.State) int {
    a := lua.CheckNumber(l, 1)
    b := lua.CheckNumber(l, 2)
    l.PushNumber(a + b)
    return 1
})

lua.DoString(l, `print(add(2, 3))`) // 5

Test suite status

We run the official Lua 5.4 test suites. Currently 21 out of 25 pass:

Test	Status	Notes
bitwise	Pass
calls	Pass
closure	Pass
code	Pass
constructs	Pass
coroutine	Pass
db (debug)	Pass
errors	Pass
events	Pass
files	Pass
goto	Pass
literals	Pass
locals	Pass
math	Pass
nextvar	Pass
pm (pattern matching)	Pass
sort	Pass
strings	Pass
tpack (string.pack)	Pass
utf8	Pass
vararg	Pass
attrib	—	Needs weak references
gc	—	Go's GC, not controllable like Lua's
big	—	Tables with >$2^{18}$ elements
main	—	Requires standalone Lua binary

Known limitations

• No weak references — __mode on metatables is not supported (Go's GC doesn't offer that hook)
• No C API — pure Go, so C Lua libraries won't work (that's kind of the point though)

Development

git clone https://github.com/speedata/go-lua.git
go build ./...
go test ./...

Some tests optionally use luac 5.4 for compiling Lua source to bytecode. If it's not in your PATH, those tests get skipped automatically.

License

MIT — see LICENSE.md.

Originally forked from Shopify/go-lua.