mirror of
https://github.com/minetest/minetest.git
synced 2024-12-23 22:52:25 +01:00
208 lines
7.7 KiB
Lua
208 lines
7.7 KiB
Lua
-- Minetest: builtin/serialize.lua
|
|
|
|
-- https://github.com/fab13n/metalua/blob/no-dll/src/lib/serialize.lua
|
|
-- Copyright (c) 2006-2997 Fabien Fleutot <metalua@gmail.com>
|
|
-- License: MIT
|
|
--------------------------------------------------------------------------------
|
|
-- Serialize an object into a source code string. This string, when passed as
|
|
-- an argument to deserialize(), returns an object structurally identical
|
|
-- to the original one. The following are currently supported:
|
|
-- * strings, numbers, booleans, nil
|
|
-- * tables thereof. Tables can have shared part, but can't be recursive yet.
|
|
-- Caveat: metatables and environments aren't saved.
|
|
--------------------------------------------------------------------------------
|
|
|
|
local no_identity = { number=1, boolean=1, string=1, ['nil']=1 }
|
|
|
|
function minetest.serialize(x)
|
|
|
|
local gensym_max = 0 -- index of the gensym() symbol generator
|
|
local seen_once = { } -- element->true set of elements seen exactly once in the table
|
|
local multiple = { } -- element->varname set of elements seen more than once
|
|
local nested = { } -- transient, set of elements currently being traversed
|
|
local nest_points = { }
|
|
local nest_patches = { }
|
|
|
|
local function gensym()
|
|
gensym_max = gensym_max + 1 ; return gensym_max
|
|
end
|
|
|
|
-----------------------------------------------------------------------------
|
|
-- nest_points are places where a table appears within itself, directly or not.
|
|
-- for instance, all of these chunks create nest points in table x:
|
|
-- "x = { }; x[x] = 1", "x = { }; x[1] = x", "x = { }; x[1] = { y = { x } }".
|
|
-- To handle those, two tables are created by mark_nest_point:
|
|
-- * nest_points [parent] associates all keys and values in table parent which
|
|
-- create a nest_point with boolean `true'
|
|
-- * nest_patches contain a list of { parent, key, value } tuples creating
|
|
-- a nest point. They're all dumped after all the other table operations
|
|
-- have been performed.
|
|
--
|
|
-- mark_nest_point (p, k, v) fills tables nest_points and nest_patches with
|
|
-- informations required to remember that key/value (k,v) create a nest point
|
|
-- in table parent. It also marks `parent' as occuring multiple times, since
|
|
-- several references to it will be required in order to patch the nest
|
|
-- points.
|
|
-----------------------------------------------------------------------------
|
|
local function mark_nest_point (parent, k, v)
|
|
local nk, nv = nested[k], nested[v]
|
|
assert (not nk or seen_once[k] or multiple[k])
|
|
assert (not nv or seen_once[v] or multiple[v])
|
|
local mode = (nk and nv and "kv") or (nk and "k") or ("v")
|
|
local parent_np = nest_points [parent]
|
|
local pair = { k, v }
|
|
if not parent_np then parent_np = { }; nest_points [parent] = parent_np end
|
|
parent_np [k], parent_np [v] = nk, nv
|
|
table.insert (nest_patches, { parent, k, v })
|
|
seen_once [parent], multiple [parent] = nil, true
|
|
end
|
|
|
|
-----------------------------------------------------------------------------
|
|
-- First pass, list the tables and functions which appear more than once in x
|
|
-----------------------------------------------------------------------------
|
|
local function mark_multiple_occurences (x)
|
|
if no_identity [type(x)] then return end
|
|
if seen_once [x] then seen_once [x], multiple [x] = nil, true
|
|
elseif multiple [x] then -- pass
|
|
else seen_once [x] = true end
|
|
|
|
if type (x) == 'table' then
|
|
nested [x] = true
|
|
for k, v in pairs (x) do
|
|
if nested[k] or nested[v] then mark_nest_point (x, k, v) else
|
|
mark_multiple_occurences (k)
|
|
mark_multiple_occurences (v)
|
|
end
|
|
end
|
|
nested [x] = nil
|
|
end
|
|
end
|
|
|
|
local dumped = { } -- multiply occuring values already dumped in localdefs
|
|
local localdefs = { } -- already dumped local definitions as source code lines
|
|
|
|
-- mutually recursive functions:
|
|
local dump_val, dump_or_ref_val
|
|
|
|
--------------------------------------------------------------------
|
|
-- if x occurs multiple times, dump the local var rather than the
|
|
-- value. If it's the first time it's dumped, also dump the content
|
|
-- in localdefs.
|
|
--------------------------------------------------------------------
|
|
function dump_or_ref_val (x)
|
|
if nested[x] then return 'false' end -- placeholder for recursive reference
|
|
if not multiple[x] then return dump_val (x) end
|
|
local var = dumped [x]
|
|
if var then return "_[" .. var .. "]" end -- already referenced
|
|
local val = dump_val(x) -- first occurence, create and register reference
|
|
var = gensym()
|
|
table.insert(localdefs, "_["..var.."]="..val)
|
|
dumped [x] = var
|
|
return "_[" .. var .. "]"
|
|
end
|
|
|
|
-----------------------------------------------------------------------------
|
|
-- Second pass, dump the object; subparts occuring multiple times are dumped
|
|
-- in local variables which can be referenced multiple times;
|
|
-- care is taken to dump locla vars in asensible order.
|
|
-----------------------------------------------------------------------------
|
|
function dump_val(x)
|
|
local t = type(x)
|
|
if x==nil then return 'nil'
|
|
elseif t=="number" then return tostring(x)
|
|
elseif t=="string" then return string.format("%q", x)
|
|
elseif t=="boolean" then return x and "true" or "false"
|
|
elseif t=="table" then
|
|
local acc = { }
|
|
local idx_dumped = { }
|
|
local np = nest_points [x]
|
|
for i, v in ipairs(x) do
|
|
if np and np[v] then
|
|
table.insert (acc, 'false') -- placeholder
|
|
else
|
|
table.insert (acc, dump_or_ref_val(v))
|
|
end
|
|
idx_dumped[i] = true
|
|
end
|
|
for k, v in pairs(x) do
|
|
if np and (np[k] or np[v]) then
|
|
--check_multiple(k); check_multiple(v) -- force dumps in localdefs
|
|
elseif not idx_dumped[k] then
|
|
table.insert (acc, "[" .. dump_or_ref_val(k) .. "] = " .. dump_or_ref_val(v))
|
|
end
|
|
end
|
|
return "{ "..table.concat(acc,", ").." }"
|
|
else
|
|
error ("Can't serialize data of type "..t)
|
|
end
|
|
end
|
|
|
|
local function dump_nest_patches()
|
|
for _, entry in ipairs(nest_patches) do
|
|
local p, k, v = unpack (entry)
|
|
assert (multiple[p])
|
|
local set = dump_or_ref_val (p) .. "[" .. dump_or_ref_val (k) .. "] = " ..
|
|
dump_or_ref_val (v) .. " -- rec "
|
|
table.insert (localdefs, set)
|
|
end
|
|
end
|
|
|
|
mark_multiple_occurences (x)
|
|
local toplevel = dump_or_ref_val (x)
|
|
dump_nest_patches()
|
|
|
|
if next (localdefs) then
|
|
return "local _={ }\n" ..
|
|
table.concat (localdefs, "\n") ..
|
|
"\nreturn " .. toplevel
|
|
else
|
|
return "return " .. toplevel
|
|
end
|
|
end
|
|
|
|
-- Deserialization.
|
|
-- http://stackoverflow.com/questions/5958818/loading-serialized-data-into-a-table
|
|
--
|
|
|
|
local function stringtotable(sdata)
|
|
if sdata:byte(1) == 27 then return nil, "binary bytecode prohibited" end
|
|
local f, message = assert(loadstring(sdata))
|
|
if not f then return nil, message end
|
|
setfenv(f, table)
|
|
return f()
|
|
end
|
|
|
|
function minetest.deserialize(sdata)
|
|
local table = {}
|
|
local okay,results = pcall(stringtotable, sdata)
|
|
if okay then
|
|
return results
|
|
end
|
|
minetest.log('error', 'minetest.deserialize(): '.. results)
|
|
return nil
|
|
end
|
|
|
|
-- Run some unit tests
|
|
local function unit_test()
|
|
function unitTest(name, success)
|
|
if not success then
|
|
error(name .. ': failed')
|
|
end
|
|
end
|
|
|
|
unittest_input = {cat={sound="nyan", speed=400}, dog={sound="woof"}}
|
|
unittest_output = minetest.deserialize(minetest.serialize(unittest_input))
|
|
|
|
unitTest("test 1a", unittest_input.cat.sound == unittest_output.cat.sound)
|
|
unitTest("test 1b", unittest_input.cat.speed == unittest_output.cat.speed)
|
|
unitTest("test 1c", unittest_input.dog.sound == unittest_output.dog.sound)
|
|
|
|
unittest_input = {escapechars="\n\r\t\v\\\"\'", noneuropean="θשׁ٩∂"}
|
|
unittest_output = minetest.deserialize(minetest.serialize(unittest_input))
|
|
unitTest("test 3a", unittest_input.escapechars == unittest_output.escapechars)
|
|
unitTest("test 3b", unittest_input.noneuropean == unittest_output.noneuropean)
|
|
end
|
|
unit_test() -- Run it
|
|
unit_test = nil -- Hide it
|
|
|