read_resource, write_resource, res_magic = ...; local cat_magic = {}; local function myerror(table, msg) error(getmetatable(table)._fullname .. ': ' .. msg); end; local function check_arg(table, key) if type(key) ~= 'string' and type(key) ~= 'number' then myerror(table, 'expecting strings as keys.'); end; if string.match(key, "^_") then myerror(table, 'resource names must not begin with "_".'); end; local t = getmetatable(table)[key]; return t, getmetatable(t); end; local new_cat; local function newindex(table, key, value) local meta = getmetatable(table); local t, mt = check_arg(table, key); if type(value) == 'table' then if mt == res_magic then myerror(table, '"' .. key .. '" is a resource.'); end; if mt == nil or mt._magic ~= cat_magic then t = new_cat(table, key); end; for k,v in pairs(value) do t[k] = v; end; else if mt ~= nil and mt._magic == cat_magic and mt._state == 1 then myerror(table, '"' .. key .. '" is a category.'); elseif mt == res_magic then write_resource(t, value); else meta[key] = value; end; end; end; local function index(table, key) local t, mt = check_arg(table, key); if mt == res_magic then return read_resource(t); end; return t; end; local function append_name(str, name) if type(name) == 'string' and string.match(name, '^%a+$') then return str .. '.' .. name; elseif type(name) == 'number' then return str .. '[' .. string.format('%g', name) .. ']'; else return nil; end; end; new_cat = function(table, key) local meta = getmetatable(table); local mt = { __newindex = newindex, __index = index, _magic = cat_magic, _fullname = append_name(meta._fullname, key), _state = 0 }; meta[key] = setmetatable({}, mt); return meta[key]; end; local function register_resource(root, name, object) local meta = getmetatable(root); meta._state = 1; local head, tail = string.match(name, '^(%a+)%.?(.*)'); local t = meta[head]; local mt = getmetatable(t); if mt ~= nil and mt._magic == cat_magic then t = mt; end; if tail == '' then if getmetatable(object) == res_magic then meta[head] = object; write_resource(object, t); else meta[head] = nil; root[head] = object; end; return t; end; if t == nil then t = new_cat(root, head); end; return register_resource(t, tail, object); end; local function dump_(key, value, fd) if type(value) == 'table' then fd:write(key, ' = {}\n'); for k, v in pairs(value) do k = append_name(key, k); local mt = getmetatable(v); if mt ~= nil and mt._magic == cat_magic then v = mt; elseif mt == res_magic then v = read_resource(v); end; if k ~= nil then dump_(k, v, fd); end; end; fd:write('\n'); else if type(value) == 'string' then value = string.format('%q', value); elseif type(value) == 'number' then value = string.format('%g', value); elseif type(value) == 'boolean' then if value then value = "true"; else value = "false"; end; else error('Unsupported value type for ' .. key .. ': ' .. type(value)); end; fd:write(key, ' = ', value, '\n'); end; end; local function dump(root, file) local fd = io.open(file, 'w'); local meta = getmetatable(root); if not string.match(meta._fullname, "^[%a]+$") then error("Someone has been messing with metatables."); end; dump_(meta._fullname, meta, fd); fd:close(); end; local function make_root(name) local t = { __newindex = newindex, __index = index, _magic = cat_magic, _fullname = name, _state = 0 }; getfenv()[name] = setmetatable({}, t); end; return make_root, register_resource, dump;