Tweak core.serialize
This adds proper support for nested tables and improves performance a bit.master
ShadowNinja
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9d69436052
commit
6afdb22ba7
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@ -1,223 +1,209 @@
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-- Minetest: builtin/serialize.lua
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-- https://github.com/fab13n/metalua/blob/no-dll/src/lib/serialize.lua
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-- Copyright (c) 2006-2997 Fabien Fleutot <metalua@gmail.com>
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--- Lua module to serialize values as Lua code.
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-- From: https://github.com/fab13n/metalua/blob/no-dll/src/lib/serialize.lua
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-- License: MIT
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--------------------------------------------------------------------------------
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-- Serialize an object into a source code string. This string, when passed as
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-- an argument to deserialize(), returns an object structurally identical
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-- to the original one. The following are currently supported:
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-- * strings, numbers, booleans, nil
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-- * tables thereof. Tables can have shared part, but can't be recursive yet.
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-- Caveat: metatables and environments aren't saved.
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-- @copyright 2006-2997 Fabien Fleutot <metalua@gmail.com>
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-- @author Fabien Fleutot <metalua@gmail.com>
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-- @author ShadowNinja <shadowninja@minetest.net>
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--------------------------------------------------------------------------------
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local no_identity = { number=1, boolean=1, string=1, ['nil']=1 }
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--- Serialize an object into a source code string. This string, when passed as
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-- an argument to deserialize(), returns an object structurally identical to
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-- the original one. The following are currently supported:
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-- * Booleans, numbers, strings, and nil.
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-- * Functions; uses interpreter-dependent (and sometimes platform-dependent) bytecode!
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-- * Tables; they can cantain multiple references and can be recursive, but metatables aren't saved.
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-- This works in two phases:
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-- 1. Recursively find and record multiple references and recursion.
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-- 2. Recursively dump the value into a string.
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-- @param x Value to serialize (nil is allowed).
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-- @return load()able string containing the value.
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function core.serialize(x)
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local local_index = 1 -- Top index of the "_" local table in the dump
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-- table->nil/1/2 set of tables seen.
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-- nil = not seen, 1 = seen once, 2 = seen multiple times.
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local seen = {}
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local gensym_max = 0 -- index of the gensym() symbol generator
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local seen_once = { } -- element->true set of elements seen exactly once in the table
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local multiple = { } -- element->varname set of elements seen more than once
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local nested = { } -- transient, set of elements currently being traversed
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local nest_points = { }
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local nest_patches = { }
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local function gensym()
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gensym_max = gensym_max + 1 ; return gensym_max
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end
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-----------------------------------------------------------------------------
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-- nest_points are places where a table appears within itself, directly or not.
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-- for instance, all of these chunks create nest points in table x:
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-- "x = { }; x[x] = 1", "x = { }; x[1] = x", "x = { }; x[1] = { y = { x } }".
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-- To handle those, two tables are created by mark_nest_point:
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-- * nest_points [parent] associates all keys and values in table parent which
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-- create a nest_point with boolean `true'
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-- * nest_patches contain a list of { parent, key, value } tuples creating
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-- a nest point. They're all dumped after all the other table operations
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-- have been performed.
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-- nest_points are places where a table appears within itself, directly
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-- or not. For instance, all of these chunks create nest points in
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-- table x: "x = {}; x[x] = 1", "x = {}; x[1] = x",
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-- "x = {}; x[1] = {y = {x}}".
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-- To handle those, two tables are used by mark_nest_point:
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-- * nested - Transient set of tables being currently traversed.
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-- Used for detecting nested tables.
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-- * nest_points - parent->{key=value, ...} table cantaining the nested
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-- keys and values in the parent. They're all dumped after all the
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-- other table operations have been performed.
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--
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-- mark_nest_point (p, k, v) fills tables nest_points and nest_patches with
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-- informations required to remember that key/value (k,v) create a nest point
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-- in table parent. It also marks `parent' as occuring multiple times, since
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-- several references to it will be required in order to patch the nest
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-- points.
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-----------------------------------------------------------------------------
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local function mark_nest_point (parent, k, v)
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-- mark_nest_point(p, k, v) fills nest_points with information required
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-- to remember that key/value (k, v) creates a nest point in table
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-- parent. It also marks "parent" and the nested item(s) as occuring
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-- multiple times, since several references to it will be required in
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-- order to patch the nest points.
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local nest_points = {}
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local nested = {}
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local function mark_nest_point(parent, k, v)
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local nk, nv = nested[k], nested[v]
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assert (not nk or seen_once[k] or multiple[k])
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assert (not nv or seen_once[v] or multiple[v])
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local mode = (nk and nv and "kv") or (nk and "k") or ("v")
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local parent_np = nest_points [parent]
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local pair = { k, v }
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if not parent_np then parent_np = { }; nest_points [parent] = parent_np end
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parent_np [k], parent_np [v] = nk, nv
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table.insert (nest_patches, { parent, k, v })
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seen_once [parent], multiple [parent] = nil, true
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local np = nest_points[parent]
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if not np then
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np = {}
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nest_points[parent] = np
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end
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np[k] = v
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seen[parent] = 2
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if nk then seen[k] = 2 end
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if nv then seen[v] = 2 end
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end
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-----------------------------------------------------------------------------
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-- First pass, list the tables and functions which appear more than once in x
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-----------------------------------------------------------------------------
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local function mark_multiple_occurences (x)
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if no_identity [type(x)] then return end
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if seen_once [x] then seen_once [x], multiple [x] = nil, true
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elseif multiple [x] then -- pass
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else seen_once [x] = true end
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if type (x) == 'table' then
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nested [x] = true
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for k, v in pairs (x) do
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if nested[k] or nested[v] then mark_nest_point (x, k, v) else
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mark_multiple_occurences (k)
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mark_multiple_occurences (v)
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-- First phase, list the tables and functions which appear more than
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-- once in x.
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local function mark_multiple_occurences(x)
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local tp = type(x)
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if tp ~= "table" and tp ~= "function" then
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-- No identity (comparison is done by value, not by instance)
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return
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end
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if seen[x] == 1 then
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seen[x] = 2
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elseif seen[x] ~= 2 then
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seen[x] = 1
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end
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if tp == "table" then
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nested[x] = true
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for k, v in pairs(x) do
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if nested[k] or nested[v] then
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mark_nest_point(x, k, v)
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else
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mark_multiple_occurences(k)
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mark_multiple_occurences(v)
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end
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end
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nested [x] = nil
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nested[x] = nil
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end
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end
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local dumped = { } -- multiply occuring values already dumped in localdefs
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local localdefs = { } -- already dumped local definitions as source code lines
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local dumped = {} -- object->varname set
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local local_defs = {} -- Dumped local definitions as source code lines
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-- mutually recursive functions:
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-- Mutually recursive local functions:
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local dump_val, dump_or_ref_val
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--------------------------------------------------------------------
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-- if x occurs multiple times, dump the local var rather than the
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-- value. If it's the first time it's dumped, also dump the content
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-- in localdefs.
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--------------------------------------------------------------------
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function dump_or_ref_val (x)
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if nested[x] then return 'false' end -- placeholder for recursive reference
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if not multiple[x] then return dump_val (x) end
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local var = dumped [x]
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if var then return "_[" .. var .. "]" end -- already referenced
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local val = dump_val(x) -- first occurence, create and register reference
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var = gensym()
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table.insert(localdefs, "_["..var.."]="..val)
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dumped [x] = var
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return "_[" .. var .. "]"
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-- If x occurs multiple times, dump the local variable rather than
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-- the value. If it's the first time it's dumped, also dump the
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-- content in local_defs.
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function dump_or_ref_val(x)
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if seen[x] ~= 2 then
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return dump_val(x)
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end
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local var = dumped[x]
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if var then -- Already referenced
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return var
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end
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-- First occurence, create and register reference
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local val = dump_val(x)
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local i = local_index
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local_index = local_index + 1
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var = "_["..i.."]"
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table.insert(local_defs, var.." = "..val)
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dumped[x] = var
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return var
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end
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-----------------------------------------------------------------------------
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-- Second pass, dump the object; subparts occuring multiple times are dumped
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-- in local variables which can be referenced multiple times;
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-- care is taken to dump locla vars in asensible order.
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-----------------------------------------------------------------------------
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-- Second phase. Dump the object; subparts occuring multiple times
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-- are dumped in local variables which can be referenced multiple
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-- times. Care is taken to dump local vars in a sensible order.
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function dump_val(x)
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local t = type(x)
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if x==nil then return 'nil'
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elseif t=="number" then return tostring(x)
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elseif t=="string" then return string.format("%q", x)
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elseif t=="boolean" then return x and "true" or "false"
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elseif t=="function" then
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local tp = type(x)
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if x == nil then return "nil"
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elseif tp == "number" then return tostring(x)
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elseif tp == "string" then return string.format("%q", x)
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elseif tp == "boolean" then return x and "true" or "false"
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elseif tp == "function" then
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return string.format("loadstring(%q)", string.dump(x))
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elseif t=="table" then
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local acc = { }
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local idx_dumped = { }
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local np = nest_points [x]
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elseif tp == "table" then
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local vals = {}
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local idx_dumped = {}
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local np = nest_points[x]
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for i, v in ipairs(x) do
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if np and np[v] then
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table.insert (acc, 'false') -- placeholder
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else
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table.insert (acc, dump_or_ref_val(v))
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if not np or not np[i] then
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table.insert(vals, dump_or_ref_val(v))
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end
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idx_dumped[i] = true
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end
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for k, v in pairs(x) do
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if np and (np[k] or np[v]) then
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--check_multiple(k); check_multiple(v) -- force dumps in localdefs
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elseif not idx_dumped[k] then
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table.insert (acc, "[" .. dump_or_ref_val(k) .. "] = " .. dump_or_ref_val(v))
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if (not np or not np[k]) and
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not idx_dumped[k] then
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table.insert(vals,
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"["..dump_or_ref_val(k).."] = "
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..dump_or_ref_val(v))
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end
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end
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return "{ "..table.concat(acc,", ").." }"
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return "{"..table.concat(vals, ", ").."}"
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else
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error ("Can't serialize data of type "..t)
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end
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end
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local function dump_nest_patches()
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for _, entry in ipairs(nest_patches) do
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local p, k, v = unpack (entry)
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assert (multiple[p])
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local set = dump_or_ref_val (p) .. "[" .. dump_or_ref_val (k) .. "] = " ..
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dump_or_ref_val (v) .. " -- rec "
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table.insert (localdefs, set)
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error("Can't serialize data of type "..t)
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end
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end
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mark_multiple_occurences (x)
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local toplevel = dump_or_ref_val (x)
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dump_nest_patches()
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local function dump_nest_points()
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for parent, vals in pairs(nest_points) do
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for k, v in pairs(vals) do
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table.insert(local_defs, dump_or_ref_val(parent)
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.."["..dump_or_ref_val(k).."] = "
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..dump_or_ref_val(v))
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end
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end
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end
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if next (localdefs) then
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return "local _={ }\n" ..
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table.concat (localdefs, "\n") ..
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"\nreturn " .. toplevel
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mark_multiple_occurences(x)
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local top_level = dump_or_ref_val(x)
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dump_nest_points()
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if next(local_defs) then
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return "local _ = {}\n"
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..table.concat(local_defs, "\n")
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.."\nreturn "..top_level
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else
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return "return " .. toplevel
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return "return "..top_level
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end
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end
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-- Deserialization.
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-- http://stackoverflow.com/questions/5958818/loading-serialized-data-into-a-table
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--
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-- Deserialization
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local env = {
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loadstring = loadstring,
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}
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local function noop() end
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local safe_env = {
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loadstring = noop,
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loadstring = function() end,
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}
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local function stringtotable(sdata, safe)
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if sdata:byte(1) == 27 then return nil, "binary bytecode prohibited" end
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local f, message = assert(loadstring(sdata))
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if not f then return nil, message end
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if safe then
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setfenv(f, safe_env)
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function core.deserialize(str, safe)
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if str:byte(1) == 0x1B then
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return nil, "Bytecode prohibited"
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end
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local f, err = loadstring(str)
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if not f then return nil, err end
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setfenv(f, safe and safe_env or env)
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local good, data = pcall(f)
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if good then
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return data
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else
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setfenv(f, env)
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return nil, data
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end
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return f()
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end
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function core.deserialize(sdata, safe)
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local table = {}
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local okay, results = pcall(stringtotable, sdata, safe)
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if okay then
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return results
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end
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core.log('error', 'core.deserialize(): '.. results)
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return nil
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end
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-- Run some unit tests
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local function unit_test()
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function unitTest(name, success)
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if not success then
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error(name .. ': failed')
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end
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end
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-- Unit tests
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local test_in = {cat={sound="nyan", speed=400}, dog={sound="woof"}}
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local test_out = core.deserialize(core.serialize(test_in))
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unittest_input = {cat={sound="nyan", speed=400}, dog={sound="woof"}}
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unittest_output = core.deserialize(core.serialize(unittest_input))
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assert(test_in.cat.sound == test_out.cat.sound)
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assert(test_in.cat.speed == test_out.cat.speed)
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assert(test_in.dog.sound == test_out.dog.sound)
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unitTest("test 1a", unittest_input.cat.sound == unittest_output.cat.sound)
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unitTest("test 1b", unittest_input.cat.speed == unittest_output.cat.speed)
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unitTest("test 1c", unittest_input.dog.sound == unittest_output.dog.sound)
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unittest_input = {escapechars="\n\r\t\v\\\"\'", noneuropean="θשׁ٩∂"}
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unittest_output = core.deserialize(core.serialize(unittest_input))
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unitTest("test 3a", unittest_input.escapechars == unittest_output.escapechars)
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unitTest("test 3b", unittest_input.noneuropean == unittest_output.noneuropean)
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end
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unit_test() -- Run it
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unit_test = nil -- Hide it
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test_in = {escape_chars="\n\r\t\v\\\"\'", non_european="θשׁ٩∂"}
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test_out = core.deserialize(core.serialize(test_in))
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assert(test_in.escape_chars == test_out.escape_chars)
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assert(test_in.non_european == test_out.non_european)
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