Minifies Lua from the command line.

minify.lua

--[[
Lua Minify 1.0
Usage:
	lua minify.lua comments DIRECTORY
		strips comments from all .lua files in the directory, recursively, and puts them in DIRECTORY/minified
	
	lua minify.lua minify DIRECTORY
		strips comments and minifies code from all .lua files and places them like the prior command.
]]

local arg = {...}

if (#arg == 0) then
	print("Invalid usage")
	--return
end

local cmd = arg[1]
local lfs = require("lfs")
local root = arg[#arg]
local out_dir = "minified"
local file_pattern = "%.lua$"
local shortable = "%s*([" .. (("[]()=*+-^{}/;,#~"):gsub(".", "%%%0")) .. "])%s*"

local function escape(str)
	return str:gsub("([%-%+%?%*%.%$%[%]%(%)%%])", "%%%0")
end

local function rescape(str)
	str = str:gsub("%%", "%%%%")
	return str
end

local function strip_comments(source)
	source = source .. "\n"
	source = source:gsub("%s*%-%-NOMINI START.-%-%-NOMINI END", "")
	source = source:gsub("%s*%-%-%[(=*)%[.-%]%1%]", "")
	source = source:gsub("%s*%-%-.-\n", "\n")
	return source
end

local function strip_whitespace(source)
	local strings = {}

	for string in source:gmatch("[^-]?(%[(=*)%[.-%]%2%])") do
		local id = #strings + 1
		strings[id] = string
		source = source:gsub(escape(string), "$" .. id .. "$")
	end

	for string in source:gmatch("(([\"']).-[^\\]?%2)") do
		local id = #strings + 1
		strings[id] = string
		source = source:gsub(escape(string), "$" .. id .. "$")
	end

	source = source:gsub("^\n+", "")
	source = source:gsub("\n+$", "")
	source = source:gsub("\n\n+", "\n")
	source = source:gsub("\t", "")

	source = source:gsub(shortable, "%1")

	for index, string in next, strings do
		source = source:gsub("%$" .. index .. "%$", rescape(string))
	end

	return source
end

local function strip_dir(dir, all, ext)
	ext = ext or ""

	for item in lfs.dir(dir) do
		if (item ~= "." and item ~= ".." and item ~= out_dir and item ~= "ldoc") then
			local path = dir .. "/" .. item
			local mode = lfs.attributes(path, "mode")

			if (mode == "file" and item:match(file_pattern)) then
				local handle = io.open(path, "r")

				if (handle) then
					local body = handle:read("*all")
					handle:close()

					local ohandle, err = io.open(root .. "/" .. out_dir .. "/" .. ext .. "/" .. item, "w")
					if (ohandle) then
						body = strip_comments(body)

						if (all) then
							body = strip_whitespace(body)
						end

						local good, err = loadstring(body)

						if (not good) then
							print(item, "failed after minify:", err)
						end

						ohandle:write(body)
						ohandle:close()
					else
						print("I/O error writing " .. root .. "/" .. out_dir .. "/" .. ext .. "/" .. item, err)
					end
				else
					print("I/O error reading " .. path)
				end
			elseif (mode == "directory") then
				lfs.mkdir(root .. "/" .. out_dir .. "/" .. ext .. "/" .. item)
				strip_dir(path, all, ext .. "/" .. item)
			end
		end
	end
end

if (cmd == "comments") then
	lfs.mkdir(root .. "/" .. out_dir)
	strip_dir(root)
	print("Stripped comments to", out_dir)
elseif (cmd == "minify") then
	lfs.mkdir(root .. "/" .. out_dir)
	strip_dir(root, true)
	print("Minified to", out_dir)
else
	print("INVALID COMMAND", cmd)
end