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[view.love.git] / json.lua
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1 --
2 -- https://github.com/rxi/json.lua
3 --
4 -- Copyright (c) 2020 rxi
5 --
6 -- Permission is hereby granted, free of charge, to any person obtaining a copy of
7 -- this software and associated documentation files (the "Software"), to deal in
8 -- the Software without restriction, including without limitation the rights to
9 -- use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
10 -- of the Software, and to permit persons to whom the Software is furnished to do
11 -- so, subject to the following conditions:
13 -- The above copyright notice and this permission notice shall be included in all
14 -- copies or substantial portions of the Software.
16 -- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17 -- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18 -- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
19 -- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20 -- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
21 -- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22 -- SOFTWARE.
25 local json = { _version = "0.1.2" }
27 -------------------------------------------------------------------------------
28 -- Encode
29 -------------------------------------------------------------------------------
31 local encode
33 local escape_char_map = {
34 [ "\\" ] = "\\",
35 [ "\"" ] = "\"",
36 [ "\b" ] = "b",
37 [ "\f" ] = "f",
38 [ "\n" ] = "n",
39 [ "\r" ] = "r",
40 [ "\t" ] = "t",
43 local escape_char_map_inv = { [ "/" ] = "/" }
44 for k, v in pairs(escape_char_map) do
45 escape_char_map_inv[v] = k
46 end
49 local function escape_char(c)
50 return "\\" .. (escape_char_map[c] or string.format("u%04x", c:byte()))
51 end
54 local function encode_nil(val)
55 return "null"
56 end
59 local function encode_table(val, stack)
60 local res = {}
61 stack = stack or {}
63 -- Circular reference?
64 if stack[val] then error("circular reference") end
66 stack[val] = true
68 if rawget(val, 1) ~= nil or next(val) == nil then
69 -- Treat as array -- check keys are valid and it is not sparse
70 local n = 0
71 for k in pairs(val) do
72 if type(k) ~= "number" then
73 error("invalid table: mixed or invalid key types")
74 end
75 n = n + 1
76 end
77 if n ~= #val then
78 error("invalid table: sparse array")
79 end
80 -- Encode
81 for i, v in ipairs(val) do
82 table.insert(res, encode(v, stack))
83 end
84 stack[val] = nil
85 return "[" .. table.concat(res, ",") .. "]"
87 else
88 -- Treat as an object
89 for k, v in pairs(val) do
90 if type(k) ~= "string" then
91 error("invalid table: mixed or invalid key types")
92 end
93 table.insert(res, encode(k, stack) .. ":" .. encode(v, stack))
94 end
95 stack[val] = nil
96 return "{" .. table.concat(res, ",") .. "}"
97 end
98 end
101 local function encode_string(val)
102 return '"' .. val:gsub('[%z\1-\31\\"]', escape_char) .. '"'
106 local function encode_number(val)
107 -- Check for NaN, -inf and inf
108 if val ~= val or val <= -math.huge or val >= math.huge then
109 error("unexpected number value '" .. tostring(val) .. "'")
111 return string.format("%.14g", val)
115 local type_func_map = {
116 [ "nil" ] = encode_nil,
117 [ "table" ] = encode_table,
118 [ "string" ] = encode_string,
119 [ "number" ] = encode_number,
120 [ "boolean" ] = tostring,
124 encode = function(val, stack)
125 local t = type(val)
126 local f = type_func_map[t]
127 if f then
128 return f(val, stack)
130 error("unexpected type '" .. t .. "'")
134 function json.encode(val)
135 return ( encode(val) )
139 -------------------------------------------------------------------------------
140 -- Decode
141 -------------------------------------------------------------------------------
143 local parse
145 local function create_set(...)
146 local res = {}
147 for i = 1, select("#", ...) do
148 res[ select(i, ...) ] = true
150 return res
153 local space_chars = create_set(" ", "\t", "\r", "\n")
154 local delim_chars = create_set(" ", "\t", "\r", "\n", "]", "}", ",")
155 local escape_chars = create_set("\\", "/", '"', "b", "f", "n", "r", "t", "u")
156 local literals = create_set("true", "false", "null")
158 local literal_map = {
159 [ "true" ] = true,
160 [ "false" ] = false,
161 [ "null" ] = nil,
165 local function next_char(str, idx, set, negate)
166 for i = idx, #str do
167 if set[str:sub(i, i)] ~= negate then
168 return i
171 return #str + 1
175 local function decode_error(str, idx, msg)
176 local line_count = 1
177 local col_count = 1
178 for i = 1, idx - 1 do
179 col_count = col_count + 1
180 if str:sub(i, i) == "\n" then
181 line_count = line_count + 1
182 col_count = 1
185 error( string.format("%s at line %d col %d", msg, line_count, col_count) )
189 local function codepoint_to_utf8(n)
190 -- http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&id=iws-appendixa
191 local f = math.floor
192 if n <= 0x7f then
193 return string.char(n)
194 elseif n <= 0x7ff then
195 return string.char(f(n / 64) + 192, n % 64 + 128)
196 elseif n <= 0xffff then
197 return string.char(f(n / 4096) + 224, f(n % 4096 / 64) + 128, n % 64 + 128)
198 elseif n <= 0x10ffff then
199 return string.char(f(n / 262144) + 240, f(n % 262144 / 4096) + 128,
200 f(n % 4096 / 64) + 128, n % 64 + 128)
202 error( string.format("invalid unicode codepoint '%x'", n) )
206 local function parse_unicode_escape(s)
207 local n1 = tonumber( s:sub(1, 4), 16 )
208 local n2 = tonumber( s:sub(7, 10), 16 )
209 -- Surrogate pair?
210 if n2 then
211 return codepoint_to_utf8((n1 - 0xd800) * 0x400 + (n2 - 0xdc00) + 0x10000)
212 else
213 return codepoint_to_utf8(n1)
218 local function parse_string(str, i)
219 local res = ""
220 local j = i + 1
221 local k = j
223 while j <= #str do
224 local x = str:byte(j)
226 if x < 32 then
227 decode_error(str, j, "control character in string")
229 elseif x == 92 then -- `\`: Escape
230 res = res .. str:sub(k, j - 1)
231 j = j + 1
232 local c = str:sub(j, j)
233 if c == "u" then
234 local hex = str:match("^[dD][89aAbB]%x%x\\u%x%x%x%x", j + 1)
235 or str:match("^%x%x%x%x", j + 1)
236 or decode_error(str, j - 1, "invalid unicode escape in string")
237 res = res .. parse_unicode_escape(hex)
238 j = j + #hex
239 else
240 if not escape_chars[c] then
241 decode_error(str, j - 1, "invalid escape char '" .. c .. "' in string")
243 res = res .. escape_char_map_inv[c]
245 k = j + 1
247 elseif x == 34 then -- `"`: End of string
248 res = res .. str:sub(k, j - 1)
249 return res, j + 1
252 j = j + 1
255 decode_error(str, i, "expected closing quote for string")
259 local function parse_number(str, i)
260 local x = next_char(str, i, delim_chars)
261 local s = str:sub(i, x - 1)
262 local n = tonumber(s)
263 if not n then
264 decode_error(str, i, "invalid number '" .. s .. "'")
266 return n, x
270 local function parse_literal(str, i)
271 local x = next_char(str, i, delim_chars)
272 local word = str:sub(i, x - 1)
273 if not literals[word] then
274 decode_error(str, i, "invalid literal '" .. word .. "'")
276 return literal_map[word], x
280 local function parse_array(str, i)
281 local res = {}
282 local n = 1
283 i = i + 1
284 while 1 do
285 local x
286 i = next_char(str, i, space_chars, true)
287 -- Empty / end of array?
288 if str:sub(i, i) == "]" then
289 i = i + 1
290 break
292 -- Read token
293 x, i = parse(str, i)
294 res[n] = x
295 n = n + 1
296 -- Next token
297 i = next_char(str, i, space_chars, true)
298 local chr = str:sub(i, i)
299 i = i + 1
300 if chr == "]" then break end
301 if chr ~= "," then decode_error(str, i, "expected ']' or ','") end
303 return res, i
307 local function parse_object(str, i)
308 local res = {}
309 i = i + 1
310 while 1 do
311 local key, val
312 i = next_char(str, i, space_chars, true)
313 -- Empty / end of object?
314 if str:sub(i, i) == "}" then
315 i = i + 1
316 break
318 -- Read key
319 if str:sub(i, i) ~= '"' then
320 decode_error(str, i, "expected string for key")
322 key, i = parse(str, i)
323 -- Read ':' delimiter
324 i = next_char(str, i, space_chars, true)
325 if str:sub(i, i) ~= ":" then
326 decode_error(str, i, "expected ':' after key")
328 i = next_char(str, i + 1, space_chars, true)
329 -- Read value
330 val, i = parse(str, i)
331 -- Set
332 res[key] = val
333 -- Next token
334 i = next_char(str, i, space_chars, true)
335 local chr = str:sub(i, i)
336 i = i + 1
337 if chr == "}" then break end
338 if chr ~= "," then decode_error(str, i, "expected '}' or ','") end
340 return res, i
344 local char_func_map = {
345 [ '"' ] = parse_string,
346 [ "0" ] = parse_number,
347 [ "1" ] = parse_number,
348 [ "2" ] = parse_number,
349 [ "3" ] = parse_number,
350 [ "4" ] = parse_number,
351 [ "5" ] = parse_number,
352 [ "6" ] = parse_number,
353 [ "7" ] = parse_number,
354 [ "8" ] = parse_number,
355 [ "9" ] = parse_number,
356 [ "-" ] = parse_number,
357 [ "t" ] = parse_literal,
358 [ "f" ] = parse_literal,
359 [ "n" ] = parse_literal,
360 [ "[" ] = parse_array,
361 [ "{" ] = parse_object,
365 parse = function(str, idx)
366 local chr = str:sub(idx, idx)
367 local f = char_func_map[chr]
368 if f then
369 return f(str, idx)
371 decode_error(str, idx, "unexpected character '" .. chr .. "'")
375 function json.decode(str)
376 if type(str) ~= "string" then
377 error("expected argument of type string, got " .. type(str))
379 local res, idx = parse(str, next_char(str, 1, space_chars, true))
380 idx = next_char(str, idx, space_chars, true)
381 if idx <= #str then
382 decode_error(str, idx, "trailing garbage")
384 return res
388 return json