luajit.cr

LuaJIT bindings for Crystal

Installation

1. Install LuaJIT

   • Linux
   • Mac
     • brew install luajit
   • Windows
     • .\scripts\build.ps1
     • See below

2. Add the dependency to your shard.yml:

dependencies:
  luajit:
    github: mdwagner/luajit.cr
    version: ~> 0.4.0

3. Run shards install

Windows

Simple

1. Run .\scripts\build.ps1 to install to ext\luajit directory

Example (powershell):

.\scripts\build.ps1
# ...build output...
crystal run src\example.cr

Advanced

If you would rather Bring-Your-Own-LuaJIT, the following changes must be made:

• Add LuaJIT directory to environment variable CRYSTAL_LIBRARY_PATH
  • NOTE: make sure to still include Crystal's compiler directory as well (can be found by running crystal env CRYSTAL_LIBRARY_PATH)
• Add LuaJIT directory to PATH
  • This isn't completely necessary, but if you plan to leverage -Dpreview_dll it's required

Usage

require "luajit"

# Basic Hello World
Luajit.run do |state|
  state.execute! <<-'LUA'
  print("Hello World!")
  LUA
end

# Crystal type to Lua object
class Account < Luajit::LuaObject
  def_class_method "new" do |state|
    _self = new
    Luajit.setup_userdata(state, _self, self)
    1
  end

  def_instance_method "deposit" do |state|
    _self = Luajit.userdata_value(state, self, 1)
    value = state.to_i(2)
    _self.deposit(value)
    0
  end

  def_instance_method "withdraw" do |state|
    _self = Luajit.userdata_value(state, self, 1)
    value = state.to_i(2)
    _self.withdraw(value)
    0
  end

  def_instance_method "get_balance" do |state|
    _self = Luajit.userdata_value(state, self, 1)
    state.push(_self.balance)
    1
  end

  property balance : Int32 = 0

  def deposit(value : Int32)
    self.balance += value
  end

  def withdraw(value : Int32)
    self.balance -= value
  end
end

Luajit.run do |state|
  Luajit.create_lua_object(state, Account)

  state.execute! <<-'LUA'
  local account = Account.new()
  account:deposit(2000)
  account:withdraw(100)
  assert(account:get_balance() == 1900)
  LUA
end

Development

• LuaJIT bindings
• Works on Windows (+build script)
• Safe wrappers
• Better tests
• Better docs + readme
• Crystal to Lua object wrapper

If you encounter any bugs, feel free to open an issue!

Contributing

1. Fork it (https://github.com/mdwagner/luajit.cr/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

Contributors

• Michael Wagner - creator and maintainer