Class: Rufus::Lua::State

Inherits:
Object
  • Object
show all
Includes:
StateMixin
Defined in:
lib/rufus/lua/state.rb

Overview

A Lua state, wraps a Lua runtime.

require 'rufus/lua'
s = Rufus::Lua::State.new
s.eval "a = 1 + 2"

p s['a'] # => 3.0

Constant Summary

Constants included from StateMixin

Rufus::Lua::StateMixin::LUA_ENVIRONINDEX, Rufus::Lua::StateMixin::LUA_GCCOLLECT, Rufus::Lua::StateMixin::LUA_GCCOUNT, Rufus::Lua::StateMixin::LUA_GCCOUNTB, Rufus::Lua::StateMixin::LUA_GCRESTART, Rufus::Lua::StateMixin::LUA_GCSETPAUSE, Rufus::Lua::StateMixin::LUA_GCSETSTEPMUL, Rufus::Lua::StateMixin::LUA_GCSTEP, Rufus::Lua::StateMixin::LUA_GCSTOP, Rufus::Lua::StateMixin::LUA_GLOBALSINDEX, Rufus::Lua::StateMixin::LUA_MULTRET, Rufus::Lua::StateMixin::LUA_NOREF, Rufus::Lua::StateMixin::LUA_REFNIL, Rufus::Lua::StateMixin::LUA_REGISTRYINDEX, Rufus::Lua::StateMixin::SIMPLE_TYPES, Rufus::Lua::StateMixin::TBOOLEAN, Rufus::Lua::StateMixin::TFUNCTION, Rufus::Lua::StateMixin::TLIGHTUSERDATA, Rufus::Lua::StateMixin::TNIL, Rufus::Lua::StateMixin::TNONE, Rufus::Lua::StateMixin::TNUMBER, Rufus::Lua::StateMixin::TSTRING, Rufus::Lua::StateMixin::TTABLE, Rufus::Lua::StateMixin::TTHREAD, Rufus::Lua::StateMixin::TUSERDATA

Instance Method Summary collapse

Constructor Details

#initialize(include_libs = true) ⇒ State

Instantiates a Lua state (runtime).

Accepts an 'include_libs' optional arg. When set to true (the default, all the base Lua libs are loaded in the runtime.

This optional arg can be set to false, when no libs should be present, or to an array of libs to load in order to prepare the state.

The list may include 'base', 'package', 'table', 'string', 'math', 'io', 'os' and 'debug'.


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# File 'lib/rufus/lua/state.rb', line 377

def initialize(include_libs=true)

  @pointer = Lib.luaL_newstate

  open_libraries(include_libs)

  #
  # preparing library methods cache

  class << @pointer
    attr_reader :__lib_method_cache
  end
  @pointer.instance_variable_set(:@__lib_method_cache, {})

  #
  # an array for preserving callback (Ruby functions) from Ruby
  # garbage collection (Scott).

  @callbacks = []

  @error_handler = 0
end

Instance Method Details

#[](k) ⇒ Object

Returns a value set at the 'global' level in the state.

state.eval('a = 1 + 2')
puts state['a'] # => "3.0"

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# File 'lib/rufus/lua/state.rb', line 441

def [](k)

  k.index('.') ?  self.eval("return #{k}") : get_global(k)
end

#[]=(k, v) ⇒ Object

Allows for setting a Lua varible immediately.

state['var'] = [ 1, 2, 3 ]
puts state['var'].to_a[0] # => 1

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# File 'lib/rufus/lua/state.rb', line 451

def []=(k, v)

  #puts; puts("#{k} = #{Rufus::Lua.to_lua_s(v)}")
  self.eval("#{k} = #{Rufus::Lua.to_lua_s(v)}")
end

#closeObject

Closes the state.

It's probably a good idea (mem leaks) to close a Lua state once you're done with it.


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# File 'lib/rufus/lua/state.rb', line 574

def close

  fail 'State already closed' unless @pointer
  Lib.lua_close(@pointer)
  @pointer = nil
end

#eval(s, bndng = nil, filename = nil, lineno = nil) ⇒ Object

Evaluates a piece (string) of Lua code within the state.


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# File 'lib/rufus/lua/state.rb', line 431

def eval(s, bndng=nil, filename=nil, lineno=nil)

  loadstring_and_call(s, bndng, filename, lineno)
end

#function(name, opts = {}, &block) ⇒ Object

Binds a Ruby function (callback) in the top environment of Lua

require 'rufus/lua'

s = Rufus::Lua::State.new

s.function 'key_up' do |table|
  table.inject({}) do |h, (k, v)|
    h[k.to_s.upcase] = v
  end
end

p s.eval(%{
  local table = {}
  table['CoW'] = 2
  table['pigs'] = 3
  table['DUCKS'] = 'none'
  return key_up(table)
}).to_h
  # => { 'COW' => 2.0, 'DUCKS => 'none', 'PIGS' => 3.0 }

s.close

:to_ruby => true

Without this option set to true, Lua tables passed to the wrapped Ruby code are instances of Rufus::Lua::Table. With this option set, rufus-lua will call #to_ruby on any parameter that responds to it (And Rufus::Lua::Table does).

s = Rufus::Lua::State.new

s.function 'is_array', :to_ruby => true do |table|
  table.is_a?(Array)
end

s.eval(return is_array({ 1, 2 }))
  # => true
s.eval(return is_array({ 'a' = 'b' }))
  # => false

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# File 'lib/rufus/lua/state.rb', line 498

def function(name, opts={}, &block)

  fail 'please pass a block for the body of the function' unless block

  to_ruby = opts[:to_ruby]

  callback =
    Proc.new do |state|

      s = CallbackState.new(state)
      args = []

      loop do

        break if s.stack_top == 0 # never touch stack[0] !!

        arg = s.stack_fetch

        args.unshift(arg)

        s.stack_unstack unless args.first.is_a?(Rufus::Lua::Ref)
      end

      while args.size < block.arity
        args << nil
      end

      args = args.collect { |a| a.respond_to?(:to_ruby) ? a.to_ruby : a } \
        if to_ruby

      s.stack_push(block.call(*args))

      1
    end

  @callbacks << callback
    # preserving the callback from garbage collection

  name = name.to_s

  name, index =
    if ri = name.rindex('.')
      #
      # bind in the given table

      table_name = name[0..ri-1]

      t = self.eval("return #{table_name}") rescue nil

      raise ArgumentError.new(
        "won't create automatically nested tables"
      ) if (not t) and table_name.index('.')

      t = self.eval("#{table_name} = {}; return #{table_name}") \
        unless t

      t.send(:load_onto_stack)

      [ name[ri+1..-1], -2 ]

    else
      #
      # bind function at the global level

      [ name, LUA_GLOBALSINDEX ]
    end

  Lib.lua_pushcclosure(@pointer, callback, 0)
  Lib.lua_setfield(@pointer, index, name)
end

#gc_collect!Object

Runs garbage collection


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# File 'lib/rufus/lua/state.rb', line 591

def gc_collect!

  fail 'State got closed, cannot proceed' unless @pointer
  Lib.lua_gc(@pointer, LUA_GCCOLLECT, 0)
end

#gc_countObject

Returns current amount of memory in KB in use by Lua


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# File 'lib/rufus/lua/state.rb', line 583

def gc_count

  fail 'State got closed, cannot proceed' unless @pointer
  Lib.lua_gc(@pointer, LUA_GCCOUNT, 0)
end

#gc_resumeObject

Restart garbage collection for this state


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# File 'lib/rufus/lua/state.rb', line 607

def gc_resume

  fail 'State got closed, cannot proceed' unless @pointer
  Lib.lua_gc(@pointer, LUA_GCRESTART, 0)
end

#gc_stopObject

Stop garbage collection for this state


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# File 'lib/rufus/lua/state.rb', line 599

def gc_stop

  fail 'State got closed, cannot proceed' unless @pointer
  Lib.lua_gc(@pointer, LUA_GCSTOP, 0)
end

#open_libraries(libs) ⇒ Object


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# File 'lib/rufus/lua/state.rb', line 637

def open_libraries(libs)

  if libs == true
    Lib.luaL_openlibs(@pointer)
  elsif libs.is_a?(Array)
    libs.each { |l| open_library(l) }
  end
end

#open_library(libname) ⇒ Object

#open_library(libname) - load a lua library via lua_call().

This is needed because is the Lua 5.1 Reference Manual Section 5 (www.lua.org/manual/5.1/manual.html#5) it says:

β€œThe luaopen_* functions (to open libraries) cannot be called directly, like a regular C function. They must be called through Lua, like a Lua function.”

β€œ..you must call them like any other Lua C function, e.g., by using lua_call.”

(by Matthew Nielsen - github.com/xunker)


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# File 'lib/rufus/lua/state.rb', line 627

def open_library(libname)

  Lib.lua_pushcclosure(
    @pointer, lambda { |ptr| Lib.send("luaopen_#{libname}", @pointer) }, 0)
  Lib.lua_pushstring(
    @pointer, (libname.to_s == "base" ? "" : libname.to_s))
  Lib.lua_call(
    @pointer, 1, 0)
end

#set_error_handler(lua_code = nil, &block) ⇒ Object


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# File 'lib/rufus/lua/state.rb', line 400

def set_error_handler(lua_code=nil, &block)

  if lua_code == nil && block

    function('_ruby_error_handler', &block)
    stack_load_path('_ruby_error_handler')
    @error_handler = stack_top

  elsif lua_code == nil

    Lib.lua_remove(@pointer, @error_handler) if @error_handler > 0
    @error_handler = 0

  elsif lua_code == :traceback

    stack_load_path('debug.traceback')
    @error_handler = stack_top

  else

    lua_code = lua_code.strip
    lua_code = 'return ' + lua_code unless lua_code.match(/^return\s+/)

    r = self.eval(lua_code)
    r.send(:load_onto_stack)
    @error_handler = stack_top
  end
end