Implementation of JavaScript array.concat() in Lua. Also, adds the function to Lua's table library

table_copy.lua

-- table.copy( array, ... ) returns a shallow copy of array. 
-- A variable number of additional arrays can be passed in as 
-- optional arguments. If an array has a hole (a nil entry), 
-- copying in a given source array stops at the last consecutive
-- item prior to the hole.
-- 
-- Note: In Lua, the function table.concat() is equivalent 
-- to JavaScript's array.join(). Hence, the following function
-- is called copy().
table.copy = function( t, ... )
	local copyShallow = function( src, dst, dstStart )
		local result = dst or {}
		local resultStart = 0
		if dst and dstStart then
			resultStart = dstStart
		end
		local resultLen = 0
		if "table" == type( src ) then
			resultLen = #src
			for i=1,resultLen do
				local value = src[i]
				if nil ~= value then
					result[i + resultStart] = value
				else
					resultLen = i - 1
					break;
				end
			end
		end
		return result,resultLen
	end

	local result, resultStart = copyShallow( t )

	local srcs = { ... }
	for i=1,#srcs do
		local _,len = copyShallow( srcs[i], result, resultStart )
		resultStart = resultStart + len
	end

	return result
end

-- Example Usage:
local t1 = {1,3,5,7,9}
local t2 = {2,4,6,333}
t2[6] = 555 -- create hole
local t3 = {11,13,17,19}

local c = table.copy( t1, t2, t3 )
print( table.concat( c, ", " ) ) -- output: 1, 3, 5, 7, 9, 2, 4, 6, 333, 11, 13, 17, 19