README.md

This is a little experiment and my first Lua project aimed at performance in LuaJIT.

Most of the code is bootstrap, but at the bottom you'll find some tests followed by some benchmarking code.

I'm surprised to find that the benchmarking code runs 4x faster with the tests included than when they're removed. In fact, just removing the print() statement at the end of the tests makes the benchmark run a lot slower. Why is this?

(Unfortunately, I haven't been able to reduce the code sample and still maintain the same behaviour.)

test.lua

local bit = require 'bit'


-- Primatives

null = {}
undefined = {}




-- Abstract functions

-- http://www.ecma-international.org/ecma-262/5.1/#sec-9.12
function isSameValue(a, b)
	-- todo
	return a == b
end


-- Custom
function isPrimitive(val)
	if val == undefined or val == null then
		return true
	end
	local t = type(val)
	return t ~= 'table'
end




-- todo objects
TypeError = {}




-- Object

-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.6
Object = {}
Object.__index = Object


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.6.2
function Object:new ()
	local o = {
		prototype = nil,
		class = 'Object',
		extensible = true,
		_properties = {},
		_propertyFlags = {}
	}

	return setmetatable(o, self)
end

	
-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.1
function Object:getOwnProperty (propertyName) 
	local band = bit.band
	local flags = self._propertyFlags[propertyName]

	-- 1
	if flags == nil then
		return
	end

	-- 2
	local newFlags = 0

	-- 3
	local value = self._properties[propertyName]

	-- 4
	if band(flags, 1--[[TYPE]]) == 0--[[DATA]] then
		newFlags = 2--[[WRITABLE]]
	end

	-- 5 NOOP

	-- 6, 7
	newFlags = bit.bor(newFlags, band(flags, 12--[[ENUMERABLE + CONFIGURABLE]]))

	-- 8
	return value, flags
end


--http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.2
function Object:getProperty (propertyName)
	-- 1
	local value, flags = self:getOwnProperty(propertyName)	

	-- 2
	if flags ~= nil then
		return value, flags
	end

	-- 3
	local proto = self.prototype

	-- 4
	if proto == nil then
		return
	end

	-- 5
	return proto:getProperty(propertyName)
end


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.3
function Object:get (propertyName) 
	-- 1
	local value, flags = self:getProperty(propertyName)

	-- 2
	if flags == nil then
		return
	end

	-- 3
	if bit.band(flags, 1--[[TYPE]]) == 0--[[DATA]] then
		return value
	end

	-- 4
	local getter = value[1--[[GETTER]]]

	-- 5
	if getter == nil then
		return
	end 

	-- 6
	return getter(self)
end


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.4
function Object:canPut (propertyName) 
	local band = bit.band

	-- 1
	local value, flags = self:getOwnProperty(propertyName)

	-- 2
	if flags ~= nil then
		-- a
		if band(flags, 1--[[TYPE]]) == 1--[[ACCESSOR]] then
			return value[2--[[SETTER]]] ~= nil
		end
		
		-- b
		return band(flags, 2--[[WRITABLE]]) == 1
	end

	-- 3
	local proto = self.prototype

	-- 4
	if proto == nil then
		return self.extensible
	end

	-- 5
	local inheritedValue, inheritedFlags = proto:getProperty(propertyName)

	-- 6
	if inheritedFlags == nil then
		return self.extensible
	end

	-- 7
	if band(inheritedFlags, 1--[[TYPE]]) == 1--[[ACCESSOR]] then
		return inherited[2--[[SETTER]]] ~= nil
	end

	-- 8a
	if not self.extensible then
		return false
	end

	-- 8b
	return band(inheritedFlags, 2--[[WRITABLE]]) == 1
end


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.5
function Object:put (propertyName, newValue, throw)

	-- 1
	if not self:canPut(property) then
		-- a
		if throw then
			error(TypeError)
		end

		-- b
		return
	end

	local band = bit.band

	-- 2
	local currentValue, currentFlags = self:getOwnProperty(propertyName)

	-- 3
	if currentFlags ~= nil and band(currentFlags, 1--[[TYPE]]) == 0--[[DATA]] then
		-- a, b
		self:defineOwnProperty(propertyName, newValue, 0, 0, throw)

		-- c
		return
	end

	-- No need to lookup property a second time if it was found the first.
	if currentFlags == nil then
		-- 4
		currentValue, currentFlags = self:getProperty(propertyName)
	end

	-- 5
	if currentFlags ~= nil and band(currentFlags, 1--[[TYPE]]) == 1--[[ACCESSOR]] then
		-- a, b
		value[2--[[SETTER]]](self, newValue)

		-- 7
		return
	end

	-- 6
	self:defineOwnProperty(propertyName, newValue, 14, 14, throw)	-- 2--[[WRITABLE]] + 4--[[ENUMERABLE]] + 8--[[CONFIGURABLE]]

	-- 7
	return
end

	
-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.6
function Object:hasProperty (propertyName)
	-- 1
	local _, flags = self:getProperty(propertyName)

	-- 2, 3
	return flags ~= nil
end


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.7
function Object:delete (propertyName, throw)
	-- 1
	local _, flags = self:getOwnProperty(propertyName)

	-- 2
	if flags == nil then
		return true
	end

	-- 3
	if bit.bind(flags, 8--[[CONFIGURABLE]]) == 1 then
		-- a
		self._properties[propertyName] = nil
		self._propertyFlags[propertyName] = nil

		-- b
		return true
	end

	-- 4
	if throw then
		error(TypeError)
	end

	-- 5
	return false

end


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.8
function Object:defaultValue (hint)
	if hint == 'string' then
		return self:_defaultValueString()

	elseif hint == 'number' then
		return self:_defaultValueNumber()

	elseif self.class == 'Date' then
		return self:_defaultValueString()
	end	

	return self:_defaultValueNumber()
end


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.8
function Object:_defaultValueString ()
	-- 1
	local toString = self:get 'toString'

	-- 2
	if type(toString) == 'function' then
		-- a
		local str = toString(self)

		-- b
		if isPrimative(str) then
			return str
		end
	end

	-- 3
	local valueOf = self:get 'valueOf'

	-- 4
	if type(valueOf) == 'function' then
		-- a
		local val = valueOf(self)

		-- b
		if isPrimative(val) then
			return val
		end
	end

	-- 5
	error(TypeError)
end


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.8
function Object:_defaultValueNumber ()
	-- 1
	local valueOf = self:get 'valueOf'

	-- 2
	if type(valueOf) == 'function' then
		-- a
		local val = valueOf(self)

		-- b
		if isPrimative(val) then
			return val
		end
	end

	-- 3
	local toString = self:get 'toString'

	-- 4
	if type(toString) == 'function' then
		-- a
		local str = toString(self)

		-- b
		if isPrimative(str) then
			return str
		end
	end

	-- 5
	error(TypeError)
end


-- http://www.ecma-international.org/ecma-262/5.1/#sec-8.12.9
function Object:defineOwnProperty (propertyName, newValue, newFlags, newFlagMask, throw)
	local band = bit.band

	-- 1
	local currentValue, currentFlags = self:getOwnProperty(propertyName)

	-- 2 NOOP

	-- 3
	if currentFlags == nil then
		if not self.extensible then
			if throw then
				error(TypeError)
			else
				return false
			end

		elseif band(newFlags, 1--[[TYPE]]) == 0--[[DATA]] or band(newFlagMask, 1--[[TYPE]]) == 0--[[NOT_SET]] then
			-- 4a
			self._properties[propertyName] = newValue
			self._propertyFlags[propertyName] = band(newFlags, 14--[[WRITABLE + ENUMBERABLE + CONFIGURABLE]])

		else
			-- 4b
			self._properties[propertyName] = newValue
			self._propertyFlags[propertyName] = band(newFlags, 12--[[ENUMBERABLE + CONFIGURABLE]])
		end

		-- 4c
		return true
	end

	-- 5
	if newValue == nil and newFlagMask == 0 then
		return true
	end

	-- 6
	-- mask may need to be used in the first condition
	if currentFlags == newFlags and isSameValue(currentValue, newValue) then
		return true
	end


	local currentConfigurable = band(currentFlags, 8--[[CONFIGURABLE]])

	-- 7
	if currentConfigurable == 0 then
		-- a, b
		if band(newFlags, 8--[[CONFIGURABLE]]) == 1 or band(currentFlags, 4--[[ENUMERABLE]]) ~= band(newFlags, 4--[[ENUMERABLE]]) then
			if throw then
				error(TypeError)
			else
				return false
			end
		end
	end

	-- 8
	if band(newFlagMask, 1--[[TYPE]]) == 0--[[NOT_SET]] then
		-- NOOP

	else
		local currentType = band(currentFlags, 1--[[TYPE]])

		-- 9
		if currentType ~= band(newFlags, 1--[[TYPE]]) then
			local currentWritable = band(currentFlags, 2--[[WRITABLE]])

			-- a
			if currentConfigurable == 0 then
				if throw then
					error(TypeError)
				else
					return false
				end
			end

			if currentType == 0--[[DATA]] then
				-- b
				self._propertyFlags[propertyName] = band(newFlags, 12) + 1 -- current(8--[[CONFIGURABLE]] + 4--[[ENUMERABLE]]) + 1--[[ACCESSOR]]
			else
				-- c
				self._propertyFlags[propertyName] = band(newFlags, 12)	-- current(8--[[CONFIGURABLE]] + 4--[[ENUMERABLE]]) + 0--[[DATA]]
			end

		elseif currentType == 0--[[DATA]] and band(newFlags, 1--[[TYPE]]) == 0--[[DATA]] then
			-- 10

			-- a
			if currentConfigurable == 0 then
				-- i
				if currentWritable == 0 then
					if band(newFlags, 2--[[WRITABLE]]) == 1 then
						if throw then
							error(TypeError)
						else
							return false
						end
					end

					-- ii
					if newValue ~= nil and not isSameValue(newValue, currentValue) then
						if throw then
							error(TypeError)
						else
							return false
						end
					end
				end
			end

			-- b NOOP

		elseif currentType == 1--[[ACCESSOR]] and band(newFlags, 1--[[TYPE]]) == 1--[[ACCESSOR]] then
			-- 11

			-- a
			if currentConfigurable == 0 then
				local newSetter = newValue[2--[[SETTER]]]
				local newGetter = newValue[1--[[GETTER]]]

				if (
					-- i
					newSetter ~= nil and not isSameValue(newSetter, currentValue[2--[[SETTER]]])
				) or (
					-- ii
					newGetter ~= nil and not isSameValue(newGetter, currentValue[1--[[GETTER]]])
				) then
					if throw then
						error(TypeError)
					else
						return false
					end
				end
			end
		end			
	end

	-- 12
	self._properties[propertyName] = newValue

	-- 13
	return true

end





-- Tests
local x = Object:new()
assert(x ~= nil, 'Object:new should create a new Object')
assert(x:get('moo') == nil, 'Object properties should be initialised nil')

x:put('moo', 'hello')
assert(x:get('moo') == 'hello', 'Object properties should return given data value [1]')

x:put('hello', 'moo')
assert(x:get('hello') == 'moo', 'Object properties should return given data value [2]')
assert(x:get('moo') == 'hello', 'Setting Object properties should not affect existing properties')

x:put('moo', 2)
assert(x:get('moo') == 2, 'Object properties with data values should be able to be overitten')

print 'ok'






-- Env
Date = Object:new()

Date:put('now', function ()
	return os.clock() * 1000
end)

console = Object:new()
console:put('log', print)




-- Translated (auto-generated) code:
local _objget=Object.get
local _objput=Object.put
local _objnew=Object.new
local xtotal=0
local ytotal=0

local start=_objget(Date,"now")()
local f=0
while (f<1000) do
local x=_objnew(Object)
_objput(x,"moo",1)
xtotal=xtotal+_objget(x,"moo")
local y=_objnew(Object)
_objput(y,"moo",1)
_objput(x,"moo",y)
local z=_objget(x,"moo")
ytotal=ytotal+_objget(z,"moo")
f=f+1
end
_objget(console,"log")(xtotal,ytotal,_objget(Date,"now")()-start)