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-- 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
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