added moon loader

moon

@@ -0,0 +1,96 @@
+#!/usr/bin/lua
+
+module("moonscript", package.seeall)
+
+require "moonscript.parse"
+require "moonscript.compile2"
+require "moonscript.util"
+
+require "alt_getopt"
+
+-- moonloader and repl
+local opts, ind = alt_getopt.get_opts(arg, "ch", { help = "h" })
+
+local help = [=[Usage: %s [options] [script [args]]
+
+    -c          Compile in memory, don't write .lua files
+    -h          Print this message
+]=]
+
+local function print_help(err)
+	if err then print("Error: "..err) end
+	print(help:format(arg[0]))
+	os.exit()
+end
+
+if opts.h then print_help() end
+
+local script = arg[ind]
+if not script then
+	print_help("repl not yet supported")
+	return
+end
+
+local dirsep = "/"
+local function create_moonpath(package_path)
+	local paths = util.split(package_path, ";")
+	for i=1,#paths do
+		local p = paths[i]:match("^(.-)%.lua$")
+		if p then
+			paths[i] = p..".moon"
+		end
+	end
+	return table.concat(paths, ";")
+end
+
+local function moon_chunk(file, file_path)
+	-- print("loading", file_path)
+	local tree, err = parse.string(file:read"*a")
+	if not tree then error("Parse error: "..err) end
+	local code = compile.tree(tree)
+
+	return load(function()
+		local out = code
+		code = nil
+		return out
+	end, file_path)
+end
+
+local function moon_loader(name)
+	name_path = name:gsub("%.", dirsep)
+	paths = util.split(package.moonpath, ";")
+
+	local file, file_path
+	for i=1,#paths do
+		file_path = paths[i]:gsub("?", name_path)
+		file = io.open(file_path)
+		if file then break end
+	end
+
+	if not file then 
+		return nil, "Could not find moon file"
+	end
+
+	return moon_chunk(file, file_path)
+end
+
+
+if not package.moonpath then
+	package.moonpath = create_moonpath(package.path)
+end
+
+table.insert(package.loaders, 2, moon_loader)
+
+local file, err = io.open(script)
+if not file then error(err) end
+
+local new_arg = { [-1] = arg[0] }
+local j = 0
+for i=ind,#arg do
+	new_arg[j] = arg[i]
+	j = j + 1
+end
+
+local chunk = moon_chunk(file, script)
+getfenv(chunk).arg = new_arg
+chunk(unpack(new_arg))