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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%w*$') then
return str .. '.' .. name;
elseif type(name) == 'number' then
return str .. '[' .. string.format('%g', name) .. ']';
else
return nil;
end;
end;
new_cat = function(table, key)
local meta = getmetatable(table);
local mt = {
__newindex = newindex, __index = index,
_magic = cat_magic, _fullname = append_name(meta._fullname, key), _state = 0
};
meta[key] = setmetatable({}, mt);
return meta[key];
end;
local function register_resource(root, name, object)
local meta = getmetatable(root);
meta._state = 1;
local head, tail = string.match(name, '^(%a%w*)%.?(.*)');
local t = meta[head];
local mt = getmetatable(t);
if tail == '' then
if mt ~= nil and mt._magic == cat_magic then
t = mt;
end;
if getmetatable(object) == res_magic then
meta[head] = object;
write_resource(object, t);
else
meta[head] = nil;
root[head] = object;
end;
return t;
end;
if mt == nil or mt._magic ~= cat_magic then
t = new_cat(root, head);
end;
return register_resource(t, tail, object);
end;
local function dump_(key, value, fd)
if type(value) == 'table' then
fd:write(key, ' = {}\n');
for k, v in pairs(value) do
k = append_name(key, k);
local mt = getmetatable(v);
if mt ~= nil and mt._magic == cat_magic then
v = mt;
elseif mt == res_magic then
v = read_resource(v);
end;
if k ~= nil then
dump_(k, v, fd);
end;
end;
fd:write('\n');
else
if type(value) == 'string' then
value = string.format('%q', value);
elseif type(value) == 'number' then
value = string.format('%g', value);
elseif type(value) == 'boolean' then
if value then
value = "true";
else
value = "false";
end;
else
error('Unsupported value type for ' .. key .. ': ' .. type(value));
end;
fd:write(key, ' = ', value, '\n');
end;
end;
local function dump(root, file)
local fd = io.open(file, 'w');
local meta = getmetatable(root);
if not string.match(meta._fullname, "^[%a]+$") 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;
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