aboutsummaryrefslogtreecommitdiffstats
path: root/util/serialization.lua
blob: 8ef8048daff49ea16fc63d24b5a9d16256867939 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
-- Prosody IM
-- Copyright (C) 2008-2010 Matthew Wild
-- Copyright (C) 2008-2010 Waqas Hussain
-- Copyright (C) 2018 Kim Alvefur
--
-- This project is MIT/X11 licensed. Please see the
-- COPYING file in the source package for more information.
--

local getmetatable = getmetatable;
local next, type = next, type;
local s_format = string.format;
local s_gsub = string.gsub;
local s_rep = string.rep;
local s_char = string.char;
local s_match = string.match;
local t_concat = table.concat;

local pcall = pcall;
local envload = require"util.envload".envload;

local pos_inf, neg_inf = math.huge, -math.huge;
-- luacheck: ignore 143/math
local m_type = math.type or function (n)
	return n % 1 == 0 and n <= 9007199254740992 and n >= -9007199254740992 and "integer" or "float";
end;

local char_to_hex = {};
for i = 0,255 do
	char_to_hex[s_char(i)] = s_format("%02x", i);
end

local function to_hex(s)
	return (s_gsub(s, ".", char_to_hex));
end

local function fatal_error(obj, why)
	error("Can't serialize "..type(obj) .. (why and ": ".. why or ""));
end

local function nonfatal_fallback(x, why)
	return s_format("nil --[[%s: %s]]", type(x), why or "fail");
end

local string_escapes = {
	['\a'] = [[\a]]; ['\b'] = [[\b]];
	['\f'] = [[\f]]; ['\n'] = [[\n]];
	['\r'] = [[\r]]; ['\t'] = [[\t]];
	['\v'] = [[\v]]; ['\\'] = [[\\]];
	['\"'] = [[\"]]; ['\''] = [[\']];
}

for i = 0, 255 do
	local c = s_char(i);
	if not string_escapes[c] then
		string_escapes[c] = s_format("\\%03d", i);
	end
end

local default_keywords = {
	["do"] = true; ["and"] = true; ["else"] = true; ["break"] = true;
	["if"] = true; ["end"] = true; ["goto"] = true; ["false"] = true;
	["in"] = true; ["for"] = true; ["then"] = true; ["local"] = true;
	["or"] = true; ["nil"] = true; ["true"] = true; ["until"] = true;
	["elseif"] = true; ["function"] = true; ["not"] = true;
	["repeat"] = true; ["return"] = true; ["while"] = true;
};

local function new(opt)
	if type(opt) ~= "table" then
		opt = { preset = opt };
	end

	local types = {
		table = true;
		string = true;
		number = true;
		boolean = true;
		["nil"] = true;
	};

	-- presets
	if opt.preset == "debug" then
		opt.preset = "oneline";
		opt.freeze = true;
		opt.fatal = false;
		opt.fallback = nonfatal_fallback;
		opt.unquoted = true;
	end
	if opt.preset == "oneline" then
		opt.indentwith = opt.indentwith or "";
		opt.itemstart = opt.itemstart or " ";
		opt.itemlast = opt.itemlast or "";
		opt.tend = opt.tend or " }";
	elseif opt.preset == "compact" then
		opt.indentwith = opt.indentwith or "";
		opt.itemstart = opt.itemstart or "";
		opt.itemlast = opt.itemlast or "";
		opt.equals = opt.equals or "=";
		opt.unquoted = true;
	end

	local fallback = opt.fallback or opt.fatal == false and nonfatal_fallback or fatal_error;

	local function ser(v)
		return (types[type(v)] or fallback)(v);
	end

	local keywords = opt.keywords or default_keywords;

	-- indented
	local indentwith = opt.indentwith or "\t";
	local itemstart = opt.itemstart or "\n";
	local itemsep = opt.itemsep or ";";
	local itemlast = opt.itemlast or ";\n";
	local tstart = opt.tstart or "{";
	local tend = opt.tend or "}";
	local kstart = opt.kstart or "[";
	local kend = opt.kend or "]";
	local equals = opt.equals or " = ";
	local unquoted = opt.unquoted == true and "^[%a_][%w_]*$" or opt.unquoted;
	local hex = opt.hex;
	local freeze = opt.freeze;
	local maxdepth = opt.maxdepth or 127;
	local multirefs = opt.multiref;

	-- serialize one table, recursively
	-- t - table being serialized
	-- o - array where tokens are added, concatenate to get final result
	--   - also used to detect cycles
	-- l - position in o of where to insert next token
	-- d - depth, used for indentation
	local function serialize_table(t, o, l, d)
		if o[t] then
			o[l], l = fallback(t, "table has multiple references"), l + 1;
			return l;
		elseif d > maxdepth then
			o[l], l = fallback(t, "max table depth reached"), l + 1;
			return l;
		end

		-- Keep track of table loops
		local ot = t; -- reference pre-freeze
		o[t] = true;
		o[ot] = true;

		if freeze == true then
			-- opportunity to do pre-serialization
			local mt = getmetatable(t);
			if type(mt) == "table" then
				local tag = mt.__name;
				local fr = mt.__freeze;

				if type(fr) == "function" then
					t = fr(t);
					if type(tag) == "string" then
						o[l], l = tag, l + 1;
					end
				end
			end
		end

		o[l], l = tstart, l + 1;
		local indent = s_rep(indentwith, d);
		local numkey = 1;
		local ktyp, vtyp;
		for k,v in next,t do
			o[l], l = itemstart, l + 1;
			o[l], l = indent, l + 1;
			ktyp, vtyp = type(k), type(v);
			if k == numkey then
				-- next index in array part
				-- assuming that these are found in order
				numkey = numkey + 1;
			elseif unquoted and ktyp == "string" and
				not keywords[k] and s_match(k, unquoted) then
				-- unquoted keys
				o[l], l = k, l + 1;
				o[l], l = equals, l + 1;
			else
				-- quoted keys
				o[l], l = kstart, l + 1;
				if ktyp == "table" then
					l = serialize_table(k, o, l, d+1);
				else
					o[l], l = ser(k), l + 1;
				end
				-- =
				o[l], o[l+1], l = kend, equals, l + 2;
			end

			-- the value
			if vtyp == "table" then
				l = serialize_table(v, o, l, d+1);
			else
				o[l], l = ser(v), l + 1;
			end
			-- last item?
			if next(t, k) ~= nil then
				o[l], l = itemsep, l + 1;
			else
				o[l], l = itemlast, l + 1;
			end
		end
		if next(t) ~= nil then
			o[l], l = s_rep(indentwith, d-1), l + 1;
		end
		o[l], l = tend, l +1;

		if multirefs then
			o[t] = nil;
			o[ot] = nil;
		end

		return l;
	end

	function types.table(t)
		local o = {};
		serialize_table(t, o, 1, 1);
		return t_concat(o);
	end

	local function serialize_string(s)
		return '"' .. s_gsub(s, "[%z\1-\31\"\'\\\127-\255]", string_escapes) .. '"';
	end

	if type(hex) == "string" then
		function types.string(s)
			local esc = serialize_string(s);
			if #esc > (#s*2+2+#hex) then
				return hex .. '"' .. to_hex(s) .. '"';
			end
			return esc;
		end
	else
		types.string = serialize_string;
	end

	function types.number(t)
		if m_type(t) == "integer" then
			return s_format("%d", t);
		elseif t == pos_inf then
			return "(1/0)";
		elseif t == neg_inf then
			return "(-1/0)";
		elseif t ~= t then
			return "(0/0)";
		end
		return s_format("%.18g", t);
	end

	-- Are these faster than tostring?
	types["nil"] = function()
		return "nil";
	end

	function types.boolean(t)
		return t and "true" or "false";
	end

	return ser;
end

local function deserialize(str)
	if type(str) ~= "string" then return nil; end
	str = "return "..str;
	local f, err = envload(str, "=serialized data", {});
	if not f then return nil, err; end
	local success, ret = pcall(f);
	if not success then return nil, ret; end
	return ret;
end

return {
	new = new;
	serialize = function (x, opt)
		return new(opt)(x);
	end;
	deserialize = deserialize;
};