modlib/luon.lua

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local assert, next, pairs, pcall, error, type, table_insert, table_concat, string_format, string_match, setmetatable, select, setfenv, math_huge, loadfile, loadstring
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= assert, next, pairs, pcall, error, type, table.insert, table.concat, string.format, string.match, setmetatable, select, setfenv, math.huge, loadfile, loadstring
local count_objects = modlib.table.count_objects
local is_identifier = modlib.text.is_identifier
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-- Build a table with the succeeding character from A-Z
local succ = {}
for char = ("A"):byte(), ("Z"):byte() - 1 do
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succ[string.char(char)] = string.char(char + 1)
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end
local function quote(string)
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return string_format("%q", string)
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end
local _ENV = {}
setfenv(1, _ENV)
local metatable = {__index = _ENV}
_ENV.metatable = metatable
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function new(self)
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return setmetatable(self, metatable)
end
function aux_write(_self, _object)
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-- returns reader, arguments
return
end
aux_read = {}
function write(self, value, write)
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local reference = {"A"}
local function increment_reference(place)
if not reference[place] then
reference[place] = "B"
elseif reference[place] == "Z" then
reference[place] = "A"
return increment_reference(place + 1)
else
reference[place] = succ[reference[place]]
end
end
local references = {}
local to_fill = {}
-- TODO sort objects by count, give frequently referenced objects shorter references
for object, count in pairs(count_objects(value)) do
local type_ = type(object)
if count >= 2 and (type_ ~= "string" or #reference + 2 < #object) then
local ref = table_concat(reference)
write(ref)
write"="
write(type_ == "table" and "{}" or quote(object))
write";"
references[object] = ref
if type_ == "table" then
to_fill[object] = ref
end
increment_reference(1)
end
end
local function is_short_key(key)
return not references[key] and type(key) == "string" and is_identifier(key)
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end
local function dump(value)
-- Primitive types
if value == nil then
return write"nil"
end
if value == true then
return write"true"
end
if value == false then
return write"false"
end
local type_ = type(value)
if type_ == "number" then
return write(string_format("%.17g", value))
end
-- Reference types: table and string
local ref = references[value]
if ref then
-- Referenced
return write(ref)
elseif type_ == "string" then
return write(quote(value))
elseif type_ == "table" then
local first = true
write"{"
local len = #value
for i = 1, len do
if not first then write";" end
dump(value[i])
first = false
end
for k, v in next, value do
if type(k) ~= "number" or k % 1 ~= 0 or k < 1 or k > len then
if not first then write";" end
if is_short_key(k) then
write(k)
else
write"["
dump(k)
write"]"
end
write"="
dump(v)
first = false
end
end
write"}"
else
-- TODO move aux_write to start, to allow dealing with metatables etc.?
(function(func, ...)
-- functions are the only way to deal with varargs
if not func then
return error("unsupported type: " .. type_)
end
write(func)
write"("
local n = select("#", ...)
local args = {...}
for i = 1, n - 1 do
dump(args[i])
write","
end
if n > 0 then
write(args[n])
end
write")"
end)(self:aux_write(value))
end
end
for table, ref in pairs(to_fill) do
for k, v in pairs(table) do
write(ref)
if is_short_key(k) then
write"."
write(k)
else
write"["
dump(k)
write"]"
end
write"="
dump(v)
write";"
end
end
write"return "
dump(value)
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end
function write_file(self, value, file)
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return self:write(value, function(text)
file:write(text)
end)
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end
function write_string(self, value)
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local rope = {}
self:write(value, function(text)
table_insert(rope, text)
end)
return table_concat(rope)
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end
function read(self, ...)
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local read = assert(...)
-- math.huge is serialized to inf, 0/0 is serialized to -nan
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-- TODO verify this is actually the case, see https://en.wikipedia.org/wiki/Printf_format_string
setfenv(read, setmetatable({inf = math_huge, nan = 0/0}, {__index = self.aux_read}))
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local success, value_or_err = pcall(read)
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if success then
return value_or_err
end
return nil, value_or_err
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end
function read_file(self, path)
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return self:read(loadfile(path))
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end
function read_string(self, string)
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return self:read(loadstring(string))
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end
return _ENV