Binder

High level go to Lua binder. Write less, do more.

This is a fork of github.com/alexeyco/binder - it has some improvements, but also backwards-incompatible changes. If you need stability, please use the original library

Package binder allows to easily bind to Lua. Based on gopher-lua.

Write less, do more!

Changes from original
Killer-feature
Installation
Examples
License

Changes from original

Fixes crashes with newer versions of gopher-lua: Now binder must be explicitly closed after use
Call functionality to call global Lua functions from Go
DoString and DoFile now return a Results struct in addition to error, so that return values from evaluated scripts can be retrieved (and cleaned from the stack)

Killer-feature

You can display detailed information about the error and get something like this:

See _example/04-highlight-errors. And read more about it.

Installation

$ go get -u github.com/olpainless/binder

To run unit tests:

$ cd $GOPATH/src/github.com/olpainless/binder
$ go test -cover

To see why you need to bind go to lua (need few minutes):

$ cd $GOPATH/src/github.com/olpainless/binder
$ go test -bench=.

Examples

Functions

package main

import (
	"errors"
	"log"

	"github.com/olpainless/binder"
)

func main() {
	b := binder.New(binder.Options{
		SkipOpenLibs: true,
	})
	defer b.Close()

	b.Func("log", func(c *binder.Context) error {
		t := c.Top()
		if t == 0 {
			return errors.New("need arguments")
		}

		l := []interface{}{}

		for i := 1; i <= t; i++ {
			l = append(l, c.Arg(i).Any())
		}

		log.Println(l...)
		return nil
	})

	if _, err := b.DoString(`
		log('This', 'is', 'Lua')
	`); err != nil {
		log.Fatalln(err)
	}
}

Modules

package main

import (
	"errors"
	"log"

	"github.com/olpainless/binder"
)

func main() {
	b := binder.New()

	m := b.Module("reverse")
	m.Func("string", func(c *binder.Context) error {
		if c.Top() == 0 {
			return errors.New("need arguments")
		}

		s := c.Arg(1).String()

		runes := []rune(s)
		for i, j := 0, len(runes)-1; i < j; i, j = i+1, j-1 {
			runes[i], runes[j] = runes[j], runes[i]
		}

		c.Push().String(string(runes))
		return nil
	})

	if _, err := b.DoString(`
		local r = require('reverse')

		print(r.string('ABCDEFGHIJKLMNOPQRSTUFVWXYZ'))
	`); err != nil {
		log.Fatalln(err)
	}
}

Tables

package main

import (
	"errors"
	"log"

	"github.com/olpainless/binder"
)

type Person struct {
	Name string
}

func main() {
	b := binder.New()

	t := b.Table("person")
	t.Static("new", func(c *binder.Context) error {
		if c.Top() == 0 {
			return errors.New("need arguments")
		}
		n := c.Arg(1).String()

		c.Push().Data(&Person{n}, "person")
		return nil
	})

	t.Dynamic("name", func(c *binder.Context) error {
		p, ok := c.Arg(1).Data().(*Person)
		if !ok {
			return errors.New("person expected")
		}

		if c.Top() == 1 {
			c.Push().String(p.Name)
		} else {
			p.Name = c.Arg(2).String()
		}

		return nil
	})

	if _, err := b.DoString(`
		local p = person.new('Steeve')
		print(p:name())

		p:name('Alice')
		print(p:name())
	`); err != nil {
		log.Fatalln(err)
	}
}

Calling Lua functions from Go

package main

import (
	"errors"
	"log"

	"github.com/olpainless/binder"
)

func main() {
	b := binder.New()

	b.Func("hello", func(c *binder.Context) error {
		if c.Top() == 0 {
			return errors.New("need arguments")
		}
		arg := c.Arg(1).String()

		c.Push().String("Hello " + arg)
		return nil
	})

	caller := b.Call("hello")
	caller.Args().String("World")
	result, err := caller.Execute()
	if err != nil {
		log.Fatalln(err)
	}

	log.Println(result.Get(1).String())
	result.Close()
}

Options

// Options binder options object
type Options struct {
	// CallStackSize is call stack size
	CallStackSize int
	// RegistrySize is data stack size
	RegistrySize int
	// SkipOpenLibs controls whether or not libraries are opened by default
	SkipOpenLibs bool
	// IncludeGoStackTrace tells whether a Go stacktrace should be included in a Lua stacktrace when panics occur.
	IncludeGoStackTrace bool
}

Killer-featured errors

package main

import (
	"errors"
	"log"
	"os"

	"github.com/olpainless/binder"
)

type Person struct {
	Name string
}

func main() {
	b := binder.New()
	
	// ...

	if err := b.DoString(`-- some string`); err != nil {
		switch err.(type) {
		case *binder.Error:
			e := err.(*binder.Error)
			e.Print()

			os.Exit(0)
			break
		default:
			log.Fatalln(err)
		}
	}
}

Note: if SkipOpenLibs is true, not all open libs will be skipped in contrast to the basic logic of gopher-lua. If you set SkipOpenLibs to true, the following basic libraries will be loaded: all basic functions, table and package.

License

MIT License

Copyright (c) 2017 Alexey Popov

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

OlPainless / binder