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view libraries/json/json.c @ 432:b8477aeb1d9f
json.export(...): avoid exponential notation for integers fitting into lua_Integer represented as float
| author | jbe |
|---|---|
| date | Thu Jan 14 19:09:49 2016 +0100 (2016-01-14) |
| parents | 4a33becb6f59 |
| children | 0bbf7717ebfd |
line source
1 #include <lua.h>
2 #include <lauxlib.h>
3 #include <stdlib.h>
4 #include <string.h>
5 #include <math.h>
6 #include <stdint.h>
7 /* TODO: stdint.h only needed for Lua 5.2 compatibility */
9 // maximum number of nested JSON values (objects and arrays):
10 // NOTE: json_import can store 2^32 / 3 levels on stack swap (using
11 // also negative indicies after integer wraparound), and
12 // json_export can store even more levels, so 1024^3 =
13 // 1073741824 is a safe value and allows practically unlimited
14 // levels for JSON documents <= 2 GiB.
15 #define JSON_MAXDEPTH (1024*1024*1024)
17 // define type JSON_LIGHTUSERDATA and
18 // generate dummy memory addresses for lightuserdata values:
19 #define JSON_LIGHTUSERDATA char
20 static struct {
21 JSON_LIGHTUSERDATA nullmark; // lightuserdata value represents a NULL value
22 JSON_LIGHTUSERDATA shadowtbl; // lightuserdata key for shadow table
23 } json_lightuserdata;
25 // macros for special nullmark value:
26 #define json_isnullmark(L, i) (lua_touserdata((L), (i)) == &json_lightuserdata.nullmark)
27 #define json_pushnullmark(L) lua_pushlightuserdata((L), &json_lightuserdata.nullmark)
29 // macros for getting and setting shadow tables
30 #define json_setshadow(L, i) lua_rawsetp((L), (i), &json_lightuserdata.shadowtbl)
31 #define json_getshadow(L, i) lua_rawgetp((L), (i), &json_lightuserdata.shadowtbl)
32 #define json_createproxy(L) lua_createtable((L), 0, 1)
34 // generate additional dummy memory addresses that represent Lua objects
35 // via lightuserdata keys and LUA_REGISTRYINDEX:
36 static struct {
37 JSON_LIGHTUSERDATA objectmt; // metatable for JSON objects
38 JSON_LIGHTUSERDATA arraymt; // metatable for JSON arrays
39 } json_registry;
41 // macros for usage of Lua registry:
42 #define json_regpointer(x) (&json_registry.x)
43 #define json_regfetchpointer(L, x) lua_rawgetp((L), LUA_REGISTRYINDEX, (x))
44 #define json_regfetch(L, x) json_regfetchpointer(L, json_regpointer(x))
45 #define json_regstore(L, x) lua_rawsetp(L, LUA_REGISTRYINDEX, json_regpointer(x))
47 // returns the string "<JSON null marker>":
48 static int json_nullmark_tostring(lua_State *L) {
49 lua_pushliteral(L, "<JSON null marker>");
50 return 1;
51 }
53 #define json_object_source_idx 1
54 #define json_object_iterator_idx 2
55 #define json_object_output_idx 3
56 #define json_object_shadow_idx 4
57 #define json_object_iterfun_idx 5
58 #define json_object_itertbl_idx 6
60 // converts a Lua table (or any other iterable value) to a JSON object:
61 // (does never modify the argument, returns an empty object or array if argument is nil)
62 static int json_object(lua_State *L) {
63 // determine is argument is given:
64 if (lua_isnoneornil(L, json_object_source_idx)) {
65 // if no argument is given (or if argument is nil),
66 // create proxy table with shadow table, and leave proxy table on top of stack:
67 json_createproxy(L);
68 lua_newtable(L);
69 json_setshadow(L, -2);
70 } else {
71 // if an argument was given,
72 // stack shall contain only one function argument:
73 lua_settop(L, 1);
74 // check if there is an iterator function in its metatable:
75 if (luaL_getmetafield(L, json_object_source_idx, "__pairs")) {
76 // if there is an iterator function,
77 // leave it on stack position 2 and verify its type:
78 if (lua_type(L, json_object_iterator_idx) != LUA_TFUNCTION)
79 return luaL_error(L, "__pairs metamethod is not a function");
80 } else {
81 // if there is no iterator function,
82 // verify the type of the argument itself:
83 luaL_checktype(L, json_object_source_idx, LUA_TTABLE);
84 // push nil onto stack position 2:
85 lua_pushnil(L);
86 }
87 // create result table on stack position 3:
88 json_createproxy(L);
89 // create shadow table on stack position 4:
90 lua_newtable(L);
91 lua_pushvalue(L, -1);
92 json_setshadow(L, -3);
93 // check if iterator function exists:
94 if (lua_isnil(L, json_object_iterator_idx)) {
95 // if there is no iterator function,
96 // copy all string key value pairs to shadow table:
97 for (lua_pushnil(L); lua_next(L, json_object_source_idx); lua_pop(L, 1)) {
98 if (lua_type(L, -2) == LUA_TSTRING) {
99 lua_pushvalue(L, -2);
100 lua_pushvalue(L, -2);
101 lua_rawset(L, json_object_shadow_idx);
102 }
103 }
104 } else {
105 // if there is an iterator function,
106 // call iterator function with source value (first argument)
107 // and store 3 result values on stack positions 5 through 7:
108 lua_pushvalue(L, json_object_iterator_idx);
109 lua_pushvalue(L, 1);
110 lua_call(L, 1, 3);
111 // iterate through key value pairs and store some of them in shadow table
112 // while replacing nil values with null-marker:
113 while (1) {
114 // call iterfun function:
115 lua_pushvalue(L, json_object_iterfun_idx);
116 lua_pushvalue(L, json_object_itertbl_idx);
117 lua_pushvalue(L, -3);
118 lua_remove(L, -4);
119 lua_call(L, 2, 2);
120 // break iteration loop if key is nil:
121 if (lua_isnil(L, -2)) break;
122 // store key value pair only if key type is correct:
123 if (lua_type(L, -2) == LUA_TSTRING) {
124 // if key type is correct,
125 // push key onto stack:
126 lua_pushvalue(L, -2);
127 // if value is nil, push null-marker onto stack (as value):
128 if (lua_isnil(L, -2)) json_pushnullmark(L);
129 // else push value onto stack:
130 else lua_pushvalue(L, -2);
131 // set key value pair in shadow table:
132 lua_rawset(L, json_object_shadow_idx);
133 }
134 // pop value from stack, but leave key on stack:
135 lua_pop(L, 1);
136 }
137 }
138 // let result table be on top of stack:
139 lua_settop(L, json_object_output_idx);
140 }
141 // set metatable (for result table on top of stack):
142 json_regfetch(L, objectmt);
143 lua_setmetatable(L, -2);
144 // return table on top of stack:
145 return 1;
146 }
148 #define json_array_source_idx 1
149 #define json_array_output_idx 2
150 #define json_array_shadow_idx 3
152 // converts a Lua table (or any other iterable value) to a JSON array:
153 // (does never modify the argument, returns an empty object or array if argument is nil)
154 static int json_array(lua_State *L) {
155 // determine is argument is given:
156 if (lua_isnoneornil(L, json_array_source_idx)) {
157 // if no argument is given (or if argument is nil),
158 // create proxy table with shadow table, and leave proxy table on top of stack:
159 json_createproxy(L);
160 lua_newtable(L);
161 json_setshadow(L, -2);
162 } else {
163 lua_Integer arrayidx, arraylen;
164 // if an argument was given,
165 // stack shall contain only one function argument:
166 lua_settop(L, 1);
167 // create result table on stack position 2:
168 json_createproxy(L);
169 // create shadow table on stack position 3:
170 lua_newtable(L);
171 lua_pushvalue(L, -1);
172 json_setshadow(L, -3);
173 // determine length of array:
174 arraylen = luaL_len(L, json_array_source_idx);
175 // for an array, copy consecutive integer value pairs to shadow table:
176 for (arrayidx=0; arrayidx<arraylen; ) {
177 // increment arrayidx at head of loop:
178 arrayidx++;
179 // get next array entry:
180 lua_pushinteger(L, arrayidx);
181 lua_gettable(L, json_array_source_idx);
182 // check if value is nil:
183 if (lua_isnil(L, -1)) {
184 // if yes, replace it with null-marker:
185 lua_pop(L, 1);
186 json_pushnullmark(L);
187 }
188 // store value in shadow table:
189 lua_rawseti(L, json_array_shadow_idx, arrayidx);
190 }
191 // let result table be on top of stack:
192 lua_settop(L, json_array_output_idx);
193 }
194 // set metatable (for result table on top of stack):
195 json_regfetch(L, arraymt);
196 lua_setmetatable(L, -2);
197 // return table on top of stack:
198 return 1;
199 }
201 // internal states of JSON parser:
202 #define JSON_STATE_VALUE 0
203 #define JSON_STATE_OBJECT_KEY 1
204 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
205 #define JSON_STATE_OBJECT_VALUE 3
206 #define JSON_STATE_OBJECT_SEPARATOR 4
207 #define JSON_STATE_ARRAY_VALUE 5
208 #define JSON_STATE_ARRAY_SEPARATOR 6
209 #define JSON_STATE_END 7
211 // special Lua stack indicies for json_import function:
212 #define json_import_objectmt_idx 2
213 #define json_import_arraymt_idx 3
214 #define json_import_stackswap_idx 4
216 // macros for hex decoding:
217 #define json_utf16_surrogate(x) ((x) >= 0xD800 && (x) <= 0xDFFF)
218 #define json_utf16_lead(x) ((x) >= 0xD800 && (x) <= 0xDBFF)
219 #define json_utf16_tail(x) ((x) >= 0xDC00 && (x) <= 0xDFFF)
220 #define json_import_readhex(x) \
221 do { \
222 x = 0; \
223 for (i=0; i<4; i++) { \
224 x <<= 4; \
225 c = str[pos++]; \
226 if (c >= '0' && c <= '9') x += c - '0'; \
227 else if (c >= 'A' && c <= 'F') x += c - 'A' + 10; \
228 else if (c >= 'a' && c <= 'f') x += c - 'a' + 10; \
229 else if (c == 0) goto json_import_unexpected_eof; \
230 else goto json_import_unexpected_escape; \
231 } \
232 } while (0)
234 // decodes a JSON document:
235 static int json_import(lua_State *L) {
236 int stackswapidx = 0; // elements in stack swap table
237 int i; // loop variable
238 const char *str; // string to parse
239 size_t total; // total length of string to parse
240 size_t pos = 0; // current position in string to parse
241 size_t level = 0; // nested levels of objects/arrays currently being processed
242 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
243 unsigned char c; // variable to store a single character to be processed (unsigned!)
244 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
245 char *cbuf; // C buffer to decode JSON string values
246 size_t outlen; // maximum length or write position of C buffer
247 long codepoint; // decoded UTF-16 character or higher codepoint
248 long utf16tail; // second decoded UTF-16 character (surrogate tail)
249 size_t arraylen; // variable to temporarily store the array length
250 // require string as argument and convert to C string with length information:
251 str = luaL_checklstring(L, 1, &total);
252 // if string contains a NULL byte, this is a syntax error
253 if (strlen(str) != total) goto json_import_syntax_error;
254 // stack shall contain one function argument:
255 lua_settop(L, 1);
256 // push objectmt onto stack position 2:
257 json_regfetch(L, objectmt);
258 // push arraymt onto stack position 3:
259 json_regfetch(L, arraymt);
260 // push table for stack swapping onto stack position 5:
261 // (needed to avoid Lua stack overflows)
262 lua_newtable(L);
263 // main loop of parser:
264 json_import_loop:
265 // skip whitespace and store next character in variable 'c':
266 while (c = str[pos],
267 c == ' ' ||
268 c == '\f' ||
269 c == '\n' ||
270 c == '\r' ||
271 c == '\t' ||
272 c == '\v'
273 ) pos++;
274 // NOTE: variable c needs to be unsigned in the following code
275 // switch statement to handle certain (single) characters:
276 switch (c) {
277 // handle end of JSON document:
278 case 0:
279 // if end of JSON document was expected, then return top element of stack as result:
280 if (mode == JSON_STATE_END) return 1;
281 // otherwise, the JSON document was malformed:
282 if (level == 0) {
283 lua_pushnil(L);
284 lua_pushliteral(L, "Empty string");
285 } else {
286 json_import_unexpected_eof:
287 lua_pushnil(L);
288 lua_pushliteral(L, "Unexpected end of JSON document");
289 }
290 return 2;
291 // new JSON object or JSON array:
292 case '{':
293 case '[':
294 // if an encountered JSON object is not expected here, then return an error:
295 if (
296 c == '{' &&
297 mode != JSON_STATE_VALUE &&
298 mode != JSON_STATE_OBJECT_VALUE &&
299 mode != JSON_STATE_ARRAY_VALUE
300 ) goto json_import_syntax_error;
301 // if an encountered JSON array is not expected here, then return an error:
302 if (
303 c == '[' &&
304 mode != JSON_STATE_VALUE &&
305 mode != JSON_STATE_OBJECT_VALUE &&
306 mode != JSON_STATE_ARRAY_VALUE
307 ) goto json_import_syntax_error;
308 // consume input character:
309 pos++;
310 // limit nested levels:
311 if (level >= JSON_MAXDEPTH) {
312 lua_pushnil(L);
313 lua_pushfstring(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
314 return 2;
315 }
316 // swap Lua stack entries for previous level to swap table:
317 // (avoids depth limitations due to Lua stack size)
318 if (level) {
319 lua_rawseti(L, json_import_stackswap_idx, ++stackswapidx);
320 lua_rawseti(L, json_import_stackswap_idx, ++stackswapidx);
321 lua_rawseti(L, json_import_stackswap_idx, ++stackswapidx);
322 }
323 // increment level:
324 level++;
325 // create JSON object or JSON array on stack:
326 lua_newtable(L);
327 // set metatable of JSON object or JSON array:
328 lua_pushvalue(L, c == '{' ? json_import_objectmt_idx : json_import_arraymt_idx);
329 lua_setmetatable(L, -2);
330 // create internal shadow table on stack:
331 lua_newtable(L);
332 // register internal shadow table:
333 lua_pushvalue(L, -1);
334 json_setshadow(L, -3);
335 // distinguish between JSON objects and JSON arrays:
336 if (c == '{') {
337 // if JSON object,
338 // expect object key (or end of object) to follow:
339 mode = JSON_STATE_OBJECT_KEY;
340 } else {
341 // if JSON array,
342 // expect array value (or end of array) to follow:
343 mode = JSON_STATE_ARRAY_VALUE;
344 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
345 if (c == '[') lua_pushnil(L);
346 }
347 goto json_import_loop;
348 // end of JSON object:
349 case '}':
350 // if end of JSON object is not expected here, then return an error:
351 if (
352 mode != JSON_STATE_OBJECT_KEY &&
353 mode != JSON_STATE_OBJECT_SEPARATOR
354 ) goto json_import_syntax_error;
355 // jump to common code for end of JSON object and JSON array:
356 goto json_import_close;
357 // end of JSON array:
358 case ']':
359 // if end of JSON array is not expected here, then return an error:
360 if (
361 mode != JSON_STATE_ARRAY_VALUE &&
362 mode != JSON_STATE_ARRAY_SEPARATOR
363 ) goto json_import_syntax_error;
364 // pop nil key/magic (that was needed to keep stack balance):
365 lua_pop(L, 1);
366 // continue with common code for end of JSON object and JSON array:
367 // common code for end of JSON object or JSON array:
368 json_import_close:
369 // consume input character:
370 pos++;
371 // pop shadow table:
372 lua_pop(L, 1);
373 // check if nested:
374 if (--level) {
375 // if nested,
376 // restore previous stack elements from stack swap:
377 lua_rawgeti(L, json_import_stackswap_idx, stackswapidx--);
378 lua_insert(L, -2);
379 lua_rawgeti(L, json_import_stackswap_idx, stackswapidx--);
380 lua_insert(L, -2);
381 lua_rawgeti(L, json_import_stackswap_idx, stackswapidx--);
382 lua_insert(L, -2);
383 // check if outer(!) structure is an array or object:
384 if (lua_isnil(L, -2)) {
385 // select array value processing:
386 mode = JSON_STATE_ARRAY_VALUE;
387 } else {
388 // select object value processing:
389 mode = JSON_STATE_OBJECT_VALUE;
390 }
391 // store value in outer structure:
392 goto json_import_process_value;
393 }
394 // if not nested, then expect end of JSON document and continue with loop:
395 mode = JSON_STATE_END;
396 goto json_import_loop;
397 // key terminator:
398 case ':':
399 // if key terminator is not expected here, then return an error:
400 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
401 goto json_import_syntax_error;
402 // consume input character:
403 pos++;
404 // expect object value to follow:
405 mode = JSON_STATE_OBJECT_VALUE;
406 // continue with loop:
407 goto json_import_loop;
408 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
409 case ',':
410 // branch according to parser state:
411 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
412 // expect an object key to follow:
413 mode = JSON_STATE_OBJECT_KEY;
414 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
415 // expect an array value to follow:
416 mode = JSON_STATE_ARRAY_VALUE;
417 } else {
418 // if value terminator is not expected here, then return an error:
419 goto json_import_syntax_error;
420 }
421 // consume input character:
422 pos++;
423 // continue with loop:
424 goto json_import_loop;
425 // string literal:
426 case '"':
427 // consume quote character:
428 pos++;
429 // find last character in input string:
430 outlen = pos;
431 while ((c = str[outlen]) != '"') {
432 // consume one character:
433 outlen++;
434 // handle unexpected end of JSON document:
435 if (c == 0) goto json_import_unexpected_eof;
436 // consume one extra character when encountering an escaped quote:
437 else if (c == '\\' && str[outlen] == '"') outlen++;
438 }
439 // determine buffer length:
440 outlen -= pos;
441 // check if string is non empty:
442 if (outlen) {
443 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
444 cbuf = luaL_buffinitsize(L, &luabuf, outlen);
445 outlen = 0;
446 // loop through the characters until encountering end quote:
447 while ((c = str[pos++]) != '"') {
448 // NOTE: unexpected end cannot happen anymore
449 if (c < 32 || c == 127) {
450 // do not allow ASCII control characters:
451 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
452 // by this parser to allow different encodings than Unicode
453 lua_pushnil(L);
454 lua_pushliteral(L, "Unexpected control character in JSON string");
455 return 2;
456 } else if (c == '\\') {
457 // read next char after backslash escape:
458 c = str[pos++];
459 switch (c) {
460 // unexpected end-of-string:
461 case 0:
462 goto json_import_unexpected_eof;
463 // unescaping of quotation mark, slash, and backslash:
464 case '"':
465 case '/':
466 case '\\':
467 cbuf[outlen++] = c;
468 break;
469 // unescaping of backspace:
470 case 'b': cbuf[outlen++] = '\b'; break;
471 // unescaping of form-feed:
472 case 'f': cbuf[outlen++] = '\f'; break;
473 // unescaping of new-line:
474 case 'n': cbuf[outlen++] = '\n'; break;
475 // unescaping of carriage-return:
476 case 'r': cbuf[outlen++] = '\r'; break;
477 // unescaping of tabulator:
478 case 't': cbuf[outlen++] = '\t'; break;
479 // unescaping of UTF-16 characters
480 case 'u':
481 // decode 4 hex nibbles:
482 json_import_readhex(codepoint);
483 // handle surrogate character:
484 if (json_utf16_surrogate(codepoint)) {
485 // check if first surrogate is in valid range:
486 if (json_utf16_lead(codepoint)) {
487 // require second surrogate:
488 if ((c = str[pos++]) != '\\' || (c = str[pos++]) != 'u') {
489 if (c == 0) goto json_import_unexpected_eof;
490 else goto json_import_wrong_surrogate;
491 }
492 // read 4 hex nibbles of second surrogate character:
493 json_import_readhex(utf16tail);
494 // check if second surrogate is in valid range:
495 if (!json_utf16_tail(utf16tail)) goto json_import_wrong_surrogate;
496 // calculate codepoint:
497 codepoint = 0x10000 + (utf16tail - 0xDC00) + (codepoint - 0xD800) * 0x400;
498 } else {
499 // throw error for wrong surrogates:
500 json_import_wrong_surrogate:
501 lua_pushnil(L);
502 lua_pushliteral(L, "Illegal UTF-16 surrogate in JSON string escape sequence");
503 return 2;
504 }
505 }
506 // encode as UTF-8:
507 if (codepoint < 0x80) {
508 cbuf[outlen++] = (char)codepoint;
509 } else if (codepoint < 0x800) {
510 cbuf[outlen++] = (char)(0xc0 | (codepoint >> 6));
511 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
512 } else if (codepoint < 0x10000) {
513 cbuf[outlen++] = (char)(0xe0 | (codepoint >> 12));
514 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 6) & 0x3f));
515 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
516 } else {
517 cbuf[outlen++] = (char)(0xf0 | (codepoint >> 18));
518 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 12) & 0x3f));
519 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 6) & 0x3f));
520 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
521 }
522 break;
523 // unexpected escape sequence:
524 default:
525 json_import_unexpected_escape:
526 lua_pushnil(L);
527 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
528 return 2;
529 }
530 } else {
531 // normal character:
532 cbuf[outlen++] = c;
533 }
534 }
535 // process buffer to Lua string:
536 luaL_pushresultsize(&luabuf, outlen);
537 } else {
538 // if JSON string is empty,
539 // push empty Lua string:
540 lua_pushliteral(L, "");
541 // consume closing quote:
542 pos++;
543 }
544 // continue with processing of decoded string:
545 goto json_import_process_value;
546 }
547 // process values whose type is is not deducible from a single character:
548 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
549 // try to parse number:
550 double numval;
551 char *endptr;
552 size_t endpos;
553 // use strtod() call to parse a (double precision) floating point number
554 // and to determine length of number:
555 numval = strtod(str+pos, &endptr);
556 // catch parsing errors:
557 if (endptr == str+pos) goto json_import_syntax_error;
558 // calculate end position of number:
559 endpos = endptr - str;
560 #if LUA_VERSION_NUM >= 503
561 // try alternative integer interpretation:
562 {
563 lua_Integer intval = 0;
564 size_t curpos;
565 if (c >= '0' && c <= '9') intval = c - '0';
566 for (curpos=pos+1; curpos<endpos; curpos++) {
567 lua_Integer d = str[curpos] - '0';
568 if (d < 0 || d > 9) break;
569 if (c == '-') {
570 // NOTE: rounding of negative integer division may be undefined
571 if (
572 intval == LUA_MININTEGER ||
573 -intval > (-(LUA_MININTEGER+10) - d) / 10 + 1
574 ) break;
575 intval = 10 * intval - d;
576 } else {
577 if (intval > (LUA_MAXINTEGER - d) / 10) break;
578 intval = 10 * intval + d;
579 }
580 }
581 if (curpos == endpos) lua_pushinteger(L, intval);
582 else lua_pushnumber(L, numval);
583 }
584 #endif
585 // consume characters that were parsed:
586 pos = endpos;
587 } else if (!strncmp(str+pos, "true", 4)) {
588 // consume 4 input characters for "true":
589 pos += 4;
590 // put Lua true value onto stack:
591 lua_pushboolean(L, 1);
592 } else if (!strncmp(str+pos, "false", 5)) {
593 // consume 5 input characters for "false":
594 pos += 5;
595 // put Lua false value onto stack:
596 lua_pushboolean(L, 0);
597 } else if (!strncmp(str+pos, "null", 4)) {
598 // consume 4 input characters for "null":
599 pos += 4;
600 // push special null-marker onto stack:
601 json_pushnullmark(L);
602 } else {
603 // all other cases are a syntax error:
604 goto json_import_syntax_error;
605 }
606 // process a decoded value or key value pair (expected on top of Lua stack):
607 json_import_process_value:
608 switch (mode) {
609 // an object key has been read:
610 case JSON_STATE_OBJECT_KEY:
611 // if an object key is not a string, then this is a syntax error:
612 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
613 // expect key terminator to follow:
614 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
615 // continue with loop:
616 goto json_import_loop;
617 // a key value pair has been read:
618 case JSON_STATE_OBJECT_VALUE:
619 // store key value pair in outer shadow table:
620 lua_rawset(L, -3);
621 // expect value terminator (or end of object) to follow:
622 mode = JSON_STATE_OBJECT_SEPARATOR;
623 // continue with loop:
624 goto json_import_loop;
625 // an array value has been read:
626 case JSON_STATE_ARRAY_VALUE:
627 // get current array length:
628 arraylen = lua_rawlen(L, -3);
629 // throw error if array would exceed INT_MAX-1 elements:
630 // NOTE: Lua 5.3 may support more elements, but C libraries may not
631 if (arraylen > INT_MAX-1) {
632 lua_pushnil(L);
633 lua_pushfstring(L, "Array exceeded length of %d elements", INT_MAX-1);
634 }
635 // store value in outer shadow table:
636 lua_rawseti(L, -3, arraylen + 1);
637 // expect value terminator (or end of object) to follow:
638 mode = JSON_STATE_ARRAY_SEPARATOR;
639 // continue with loop
640 goto json_import_loop;
641 // a single value has been read:
642 case JSON_STATE_VALUE:
643 // leave value on top of stack, expect end of JSON document, and continue with loop:
644 mode = JSON_STATE_END;
645 goto json_import_loop;
646 }
647 // syntax error handling (reachable by goto statement):
648 json_import_syntax_error:
649 lua_pushnil(L);
650 lua_pushliteral(L, "Syntax error in JSON document");
651 return 2;
652 }
654 // gets a value or its type from a JSON document (passed as first argument)
655 // using a path (passed as variable number of keys after the first argument):
656 static int json_path(lua_State *L, int type_mode) {
657 int stacktop; // number of arguments
658 int idx = 2; // stack index of current argument to process
659 // require at least one argument:
660 luaL_checkany(L, 1);
661 // store stack index of top of stack (number of arguments):
662 stacktop = lua_gettop(L);
663 // use first argument as "current value" (stored on top of stack):
664 lua_pushvalue(L, 1);
665 // process each "path key" (2nd argument and following arguments):
666 while (idx <= stacktop) {
667 // if "current value" (on top of stack) is nil, then the path cannot be walked and nil is returned:
668 if (lua_isnil(L, -1)) return 1;
669 // try to get shadow table of "current value":
670 json_getshadow(L, -1);
671 if (lua_isnil(L, -1)) {
672 // if no shadow table is found,
673 if (lua_type(L, -2) == LUA_TTABLE) {
674 // and if "current value" is a table,
675 // pop nil from stack:
676 lua_pop(L, 1);
677 // get "next value" using the "path key":
678 lua_pushvalue(L, idx++);
679 lua_gettable(L, -2);
680 } else {
681 // if "current value" is not a table,
682 // then the path cannot be walked and nil (already on top of stack) is returned:
683 return 1;
684 }
685 } else {
686 // if a shadow table is found,
687 // set "current value" to its shadow table:
688 lua_replace(L, -2);
689 // get "next value" using the "path key":
690 lua_pushvalue(L, idx++);
691 lua_rawget(L, -2);
692 }
693 // the "next value" replaces the "current value":
694 lua_replace(L, -2);
695 }
696 if (!type_mode) {
697 // if a value (and not its type) was requested,
698 // check if value is the null-marker, and store nil on top of Lua stack in that case:
699 if (json_isnullmark(L, -1)) lua_pushnil(L);
700 } else {
701 // if the type was requested,
702 // check if value is the null-marker:
703 if (json_isnullmark(L, -1)) {
704 // if yes, store string "null" on top of Lua stack:
705 lua_pushliteral(L, "null");
706 } else {
707 // otherwise,
708 // check if metatable indicates "object" or "array":
709 if (lua_getmetatable(L, -1)) {
710 json_regfetch(L, objectmt);
711 if (lua_rawequal(L, -2, -1)) {
712 // if value has metatable for JSON objects,
713 // return string "object":
714 lua_pushliteral(L, "object");
715 return 1;
716 }
717 json_regfetch(L, arraymt);
718 if (lua_rawequal(L, -3, -1)) {
719 // if value has metatable for JSON arrays,
720 // return string "object":
721 lua_pushliteral(L, "array");
722 return 1;
723 }
724 // remove 3 metatables (one of the value, two for comparison) from stack:
725 lua_pop(L, 3);
726 }
727 // otherwise, get the Lua type:
728 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
729 }
730 }
731 // return the top most value on the Lua stack:
732 return 1;
733 }
735 // gets a value from a JSON document (passed as first argument)
736 // using a path (passed as variable number of keys after the first argument):
737 static int json_get(lua_State *L) {
738 return json_path(L, 0);
739 }
741 // gets a value's type from a JSON document (passed as first argument)
742 // using a path (passed as variable number of keys after first the argument):
743 static int json_type(lua_State *L) {
744 return json_path(L, 1);
745 }
747 // special Lua stack indicies for json_set function:
748 #define json_set_objectmt_idx 1
749 #define json_set_arraymt_idx 2
751 // stack offset of arguments to json_set function:
752 #define json_set_idxshift 2
754 // sets a value (passed as second argument) in a JSON document (passed as first argument)
755 // using a path (passed as variable number of keys starting at third argument):
756 static int json_set(lua_State *L) {
757 int stacktop; // stack index of top of stack (after shifting)
758 int idx; // stack index of current argument to process
759 // require at least three arguments:
760 luaL_checkany(L, 1);
761 luaL_checkany(L, 2);
762 luaL_checkany(L, 3);
763 // insert objectmt into stack at position 1 (shifting the arguments):
764 json_regfetch(L, objectmt);
765 lua_insert(L, 1);
766 // insert arraymt into stack at position 2 (shifting the arguments):
767 json_regfetch(L, arraymt);
768 lua_insert(L, 2);
769 // store stack index of top of stack:
770 stacktop = lua_gettop(L);
771 // use nil as initial "parent value":
772 lua_pushnil(L);
773 // use first argument as "current value":
774 lua_pushvalue(L, 1 + json_set_idxshift);
775 // set all necessary values in path:
776 for (idx = 3 + json_set_idxshift; idx<=stacktop; idx++) {
777 // push metatable of "current value" onto stack:
778 if (!lua_getmetatable(L, -1)) lua_pushnil(L);
779 // distinguish according to type of path key:
780 switch (lua_type(L, idx)) {
781 case LUA_TSTRING:
782 // if path key is a string,
783 // check if "current value" is a JSON object (or table without metatable):
784 if (
785 lua_rawequal(L, -1, json_set_objectmt_idx) ||
786 (lua_isnil(L, -1) && lua_type(L, -2) == LUA_TTABLE)
787 ) {
788 // if "current value" is acceptable,
789 // pop metatable and leave "current value" on top of stack:
790 lua_pop(L, 1);
791 } else {
792 // if "current value" is not acceptable:
793 // pop metatable and "current value":
794 lua_pop(L, 2);
795 // throw error if parent element does not exist:
796 if (lua_isnil(L, -1)) return luaL_error(L, "Root element is not a JSON object");
797 // push new JSON object as "current value" onto stack:
798 json_createproxy(L);
799 // create and register shadow table:
800 lua_newtable(L);
801 json_setshadow(L, -2);
802 // set metatable of JSON object:
803 lua_pushvalue(L, json_set_objectmt_idx);
804 lua_setmetatable(L, -2);
805 // set entry in "parent value":
806 lua_pushvalue(L, idx-1);
807 lua_pushvalue(L, -2);
808 lua_settable(L, -4);
809 }
810 break;
811 case LUA_TNUMBER:
812 // if path key is a number,
813 // check if "current value" is a JSON array (or table without metatable):
814 if (
815 lua_rawequal(L, -1, json_set_arraymt_idx) ||
816 (lua_isnil(L, -1) && lua_type(L, -2) == LUA_TTABLE)
817 ) {
818 // if "current value" is acceptable,
819 // pop metatable and leave "current value" on top of stack:
820 lua_pop(L, 1);
821 } else {
822 // if "current value" is not acceptable:
823 // pop metatable and "current value":
824 lua_pop(L, 2);
825 // throw error if parent element does not exist:
826 if (lua_isnil(L, -1)) return luaL_error(L, "Root element is not a JSON array");
827 // push new JSON array as "current value" onto stack:
828 json_createproxy(L);
829 // create and register shadow table:
830 lua_newtable(L);
831 json_setshadow(L, -2);
832 // set metatable of JSON array:
833 lua_pushvalue(L, json_set_arraymt_idx);
834 lua_setmetatable(L, -2);
835 // set entry in "parent value":
836 lua_pushvalue(L, idx-1);
837 lua_pushvalue(L, -2);
838 lua_settable(L, -4);
839 }
840 break;
841 default:
842 return luaL_error(L, "Invalid path key of type %s", lua_typename(L, lua_type(L, idx)));
843 }
844 // check if last path element is being processed:
845 if (idx == stacktop) {
846 // if the last path element is being processed,
847 // set last path value in "current value" container:
848 lua_pushvalue(L, idx);
849 lua_pushvalue(L, 2 + json_set_idxshift);
850 lua_settable(L, -3);
851 } else {
852 // if the processed path element is not the last,
853 // use old "current value" as new "parent value"
854 lua_remove(L, -2);
855 // push new "current value" onto stack by performing a lookup:
856 lua_pushvalue(L, idx);
857 lua_gettable(L, -2);
858 }
859 }
860 // return first argument for convenience:
861 lua_settop(L, 1 + json_set_idxshift);
862 return 1;
863 }
865 // returns the length of a JSON array (or zero for a table without numeric keys):
866 static int json_len(lua_State *L) {
867 // require table as first argument:
868 luaL_checktype(L, 1, LUA_TTABLE);
869 // stack shall contain one function argument:
870 lua_settop(L, 1);
871 // push shadow table or nil onto stack:
872 json_getshadow(L, 1);
873 // pop nil from stack if no shadow table has been found:
874 if (lua_isnil(L, -1)) lua_pop(L, 1);
875 // return length of argument or shadow table:
876 lua_pushnumber(L, lua_rawlen(L, -1));
877 return 1;
878 }
880 // __index metamethod for JSON objects and JSON arrays:
881 static int json_index(lua_State *L) {
882 // require table as first argument:
883 luaL_checktype(L, 1, LUA_TTABLE);
884 // stack shall contain two function arguments:
885 lua_settop(L, 2);
886 // replace first argument with its shadow table
887 // or throw error if no shadow table is found:
888 json_getshadow(L, 1);
889 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
890 lua_replace(L, 1);
891 // use key passed as second argument to lookup value in shadow table:
892 lua_rawget(L, 1);
893 // if value is null-marker, then push nil onto stack:
894 if (json_isnullmark(L, 2)) lua_pushnil(L);
895 // return either looked up value, or nil
896 return 1;
897 }
899 // __newindex metamethod for JSON objects and JSON arrays:
900 static int json_newindex(lua_State *L) {
901 // require table as first argument
902 luaL_checktype(L, 1, LUA_TTABLE);
903 // stack shall contain three function arguments:
904 lua_settop(L, 3);
905 // replace first argument with its shadow table
906 // or throw error if no shadow table is found:
907 json_getshadow(L, 1);
908 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
909 lua_replace(L, 1);
910 // second and third argument to write to shadow table:
911 lua_rawset(L, 1);
912 // return nothing:
913 return 0;
914 }
916 // function returned as first value by json_pairs function:
917 static int json_pairs_iterfunc(lua_State *L) {
918 // require table as first argument
919 luaL_checktype(L, 1, LUA_TTABLE);
920 // stack shall contain two function arguments:
921 lua_settop(L, 2);
922 // get next key value pair from shadow table (argument 1) using previous key (argument 2)
923 // and return nothing if there is no next pair:
924 if (!lua_next(L, 1)) return 0;
925 // replace null-marker with nil:
926 if (json_isnullmark(L, -1)) {
927 lua_pop(L, 1);
928 lua_pushnil(L);
929 }
930 // return key and value (or key and nil, if null-marker was found):
931 return 2;
932 }
934 // returns a triple such that 'for key, value in pairs(obj) do ... end'
935 // iterates through all key value pairs (including JSON null values represented as Lua nil):
936 static int json_pairs(lua_State *L) {
937 // require table as first argument
938 luaL_checktype(L, 1, LUA_TTABLE);
939 // return triple of function json_pairs_iterfunc, shadow table of first argument, and nil:
940 lua_pushcfunction(L, json_pairs_iterfunc);
941 json_getshadow(L, 1);
942 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
943 lua_pushnil(L);
944 return 3;
945 }
947 // function returned as first value by json_ipairs function:
948 static int json_ipairs_iterfunc(lua_State *L) {
949 lua_Integer idx;
950 // require table as first argument
951 luaL_checktype(L, 1, LUA_TTABLE);
952 // stack shall contain two function arguments:
953 lua_settop(L, 2);
954 // calculate new index by incrementing second argument:
955 idx = lua_tointeger(L, 2) + 1;
956 // do integer lookup in shadow table and store result on stack position 3:
957 lua_rawgeti(L, 1, idx);
958 // return nothing if there was no value:
959 if (lua_isnil(L, 3)) return 0;
960 // return new index and
961 // either the looked up value if it is not equal to the null-marker
962 // or nil instead of null-marker:
963 lua_pushinteger(L, idx);
964 if (json_isnullmark(L, 3)) lua_pushnil(L);
965 else lua_pushvalue(L, 3);
966 return 2;
967 }
969 // returns a triple such that 'for idx, value in ipairs(ary) do ... end'
970 // iterates through all values (including JSON null values represented as Lua nil):
971 static int json_ipairs(lua_State *L) {
972 // require table as first argument
973 luaL_checktype(L, 1, LUA_TTABLE);
974 // return triple of function json_ipairs_iterfunc, shadow table of first argument, and zero:
975 lua_pushcfunction(L, json_ipairs_iterfunc);
976 json_getshadow(L, 1);
977 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
978 lua_pushinteger(L, 0);
979 return 3;
980 }
982 // datatype representing a table key:
983 // (used for sorting)
984 typedef struct {
985 size_t length;
986 const char *data;
987 } json_key_t;
989 // comparation function for table keys to be passed to qsort function:
990 static int json_key_cmp(json_key_t *key1, json_key_t *key2) {
991 size_t pos = 0;
992 unsigned char c1, c2;
993 while (1) {
994 if (key1->length > pos) {
995 if (key2->length > pos) {
996 c1 = key1->data[pos];
997 c2 = key2->data[pos];
998 if (c1 < c2) return -1;
999 else if (c1 > c2) return 1;
1000 } else {
1001 return 1;
1002 }
1003 } else {
1004 if (key2->length > pos) {
1005 return -1;
1006 } else {
1007 return 0;
1008 }
1009 }
1010 pos++;
1011 }
1012 }
1014 // constants for type detection of ambiguous tables:
1015 #define JSON_TABLETYPE_UNKNOWN 0
1016 #define JSON_TABLETYPE_OBJECT 1
1017 #define JSON_TABLETYPE_ARRAY 2
1019 typedef struct {
1020 int type;
1021 int pos;
1022 int count;
1023 json_key_t keys[1]; // or more
1024 } json_container_t;
1026 // special Lua stack indicies for json_export function:
1027 #define json_export_value_idx 1
1028 #define json_export_indentstring_idx 2
1029 #define json_export_objectmt_idx 3
1030 #define json_export_arraymt_idx 4
1031 #define json_export_stackswap_idx 5
1032 #define json_export_luacontainer_idx 6
1033 #define json_export_ccontainer_idx 7
1034 #define json_export_buffer_idx 8
1036 // encodes a JSON document (passed as first argument)
1037 // optionally using indentation (indentation string or true passed as second argument)
1038 static int json_export(lua_State *L) {
1039 int pretty; // pretty printing on? (i.e. printing with indentation)
1040 luaL_Buffer buf; // Lua buffer containing result string
1041 lua_Number num; // number to encode
1042 char numstr[80]; // encoded number
1043 // (21 chars needed for sign, zero, point, 17 significant digits, and NULL byte)
1044 // (21 chars needed for sign, 19 digits INT64, and NULL byte)
1045 // (80 chars needed for sign, 78 digits INT256, and NULL byte)
1046 // (NOTE: we don't know the size of intmax_t and thus use 80)
1047 const char *str; // string to encode
1048 size_t strlen; // length of string to encode
1049 size_t strpos ; // position in string or position of current key
1050 unsigned char c; // character to encode (unsigned!)
1051 char hexcode[7]; // store for unicode hex escape sequence
1052 // NOTE: 7 bytes due to backslash, character 'u', 4 hex digits, and terminating NULL byte
1053 int tabletype; // table type: unknown, JSON object, or JSON array
1054 size_t keycount = 0; // number of string keys in object
1055 json_key_t *key; // pointer to C structure containing a string key
1056 int level = 0; // current depth level
1057 int i; // iteration variable for level dependent repetitions
1058 int stackswapidx = 0; // elements in stack swap table
1059 int containerkey = 0; // temporarily set to 1, if a container key is being encoded
1060 json_container_t *container = NULL; // pointer to current C struct for container information
1061 // stack shall contain two function arguments:
1062 lua_settop(L, 2);
1063 // check if pretty printing (with indentation) is desired:
1064 if (lua_toboolean(L, json_export_indentstring_idx)) {
1065 // if yes,
1066 // set pretty variable to 1:
1067 pretty = 1;
1068 // check if second argument is a boolean (true):
1069 if (lua_isboolean(L, json_export_indentstring_idx)) {
1070 // if yes,
1071 // use default indentation if indentation argument is boolean true:
1072 lua_pushliteral(L, " ");
1073 lua_replace(L, json_export_indentstring_idx);
1074 } else {
1075 // if no,
1076 // require second argument to be a string:
1077 luaL_checktype(L, json_export_indentstring_idx, LUA_TSTRING);
1078 }
1079 } else {
1080 // if no,
1081 // set pretty variable to 0:
1082 pretty = 0;
1083 }
1084 // push objectmt onto stack position 3:
1085 json_regfetch(L, objectmt);
1086 // push arraymt onto stack position 4:
1087 json_regfetch(L, arraymt);
1088 // push table for stack swapping onto stack position 5:
1089 lua_newtable(L);
1090 // create placeholders on stack positions 6 through 7:
1091 lua_settop(L, json_export_buffer_idx);
1092 // create Lua string buffer:
1093 luaL_buffinit(L, &buf);
1094 // loop:
1095 while (1) {
1096 // if value to encode is the null-marker, then treat it the same as nil:
1097 if (json_isnullmark(L, json_export_value_idx)) {
1098 lua_pushnil(L);
1099 lua_replace(L, json_export_value_idx);
1100 }
1101 // distinguish between different Lua types:
1102 switch (lua_type(L, json_export_value_idx)) {
1103 // value to encode is nil:
1104 case LUA_TNIL:
1105 // add string "null" to output buffer:
1106 luaL_addstring(&buf, "null");
1107 break;
1108 // value to encode is of type number:
1109 case LUA_TNUMBER:
1110 #if LUA_VERSION_NUM >= 503
1111 // handle integers:
1112 if (lua_isinteger(L, json_export_value_idx)) {
1113 sprintf(numstr, "%ji", (intmax_t)lua_tointeger(L, json_export_value_idx));
1114 luaL_addstring(&buf, numstr);
1115 break;
1116 }
1117 #endif
1118 // convert value to double precision number:
1119 num = lua_tonumber(L, json_export_value_idx);
1120 // throw error if number is not-a-number:
1121 if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
1122 // throw error if number is positive or negative infinity:
1123 if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
1124 // check if float is integral:
1125 if ((double)trunc((double)num) == (double)num) {
1126 // avoid exponential notation for integers fitting into lua_Integer represented as float:
1127 #if LUA_VERSION_NUM >= 503
1128 if (num >= LUA_MININTEGER && num <= LUA_MAXINTEGER) {
1129 #else
1130 if (num >= INT64_MIN && num <= INT64_MAX) {
1131 #endif
1132 // use decimal notation:
1133 sprintf(numstr, "%.0f", num);
1134 } else {
1135 // use maximum precision:
1136 sprintf(numstr, "%.17g", num); // NOTE: e.g. 12345678901234560
1137 }
1138 } else {
1139 // determine necessary precision to represent double precision floating point number:
1140 sprintf(numstr, "%.15g", num); // NOTE: e.g. 0.009 should not be 0.008999999999999999
1141 if (strtod(numstr, NULL) != num) sprintf(numstr, "%.16g", num);
1142 if (strtod(numstr, NULL) != num) sprintf(numstr, "%.17g", num);
1143 }
1144 // add string encoding of the number to the output buffer:
1145 luaL_addstring(&buf, numstr);
1146 #if LUA_VERSION_NUM >= 503
1147 // enforce trailing ".0" for floats unless exponential notation was chosen:
1148 {
1149 char *p;
1150 if (numstr[0] == '-' || numstr[0] == '+') p = numstr+1;
1151 else p = numstr;
1152 for (; *p; p++) if (*p < '0' || *p > '9') break;
1153 if (!*p) luaL_addstring(&buf, ".0");
1154 }
1155 #endif
1156 break;
1157 // value to encode is of type boolean:
1158 case LUA_TBOOLEAN:
1159 // add string "true" or "false" according to boolean value:
1160 luaL_addstring(&buf, lua_toboolean(L, json_export_value_idx) ? "true" : "false");
1161 break;
1162 // value to encode is of type string:
1163 case LUA_TSTRING:
1164 // add quoted and escaped string to output buffer:
1165 str = lua_tolstring(L, json_export_value_idx, &strlen);
1166 luaL_addchar(&buf, '"');
1167 strpos = 0;
1168 while (strpos < strlen) {
1169 c = str[strpos++];
1170 if (c == '"') luaL_addstring(&buf, "\\\"");
1171 else if (c == '\\') luaL_addstring(&buf, "\\\\");
1172 else if (c == 127) luaL_addstring(&buf, "\\u007F");
1173 else if (c >= 32) luaL_addchar(&buf, c);
1174 else if (c == '\b') luaL_addstring(&buf, "\\b");
1175 else if (c == '\f') luaL_addstring(&buf, "\\f");
1176 else if (c == '\n') luaL_addstring(&buf, "\\n");
1177 else if (c == '\r') luaL_addstring(&buf, "\\r");
1178 else if (c == '\t') luaL_addstring(&buf, "\\t");
1179 else if (c == '\v') luaL_addstring(&buf, "\\v");
1180 else {
1181 sprintf(hexcode, "\\u%04X", c);
1182 luaL_addstring(&buf, hexcode);
1183 }
1184 }
1185 luaL_addchar(&buf, '"');
1186 break;
1187 // value to encode is of type table (this includes JSON objects and JSON arrays):
1188 case LUA_TTABLE:
1189 // use table's metatable to try to determine type of table:
1190 tabletype = JSON_TABLETYPE_UNKNOWN;
1191 if (lua_getmetatable(L, json_export_value_idx)) {
1192 if (lua_rawequal(L, -1, json_export_objectmt_idx)) {
1193 tabletype = JSON_TABLETYPE_OBJECT;
1194 } else {
1195 if (lua_rawequal(L, -1, json_export_arraymt_idx)) {
1196 tabletype = JSON_TABLETYPE_ARRAY;
1197 } else {
1198 return luaL_error(L, "JSON export not possible for tables with nonsupported metatable");
1199 }
1200 }
1201 // reset stack (pop metatable from stack):
1202 lua_pop(L, 1);
1203 }
1204 // replace table with its shadow table if existent:
1205 json_getshadow(L, json_export_value_idx);
1206 if (lua_isnil(L, -1)) lua_pop(L, 1);
1207 else lua_replace(L, json_export_value_idx);
1208 // check if type of table is still undetermined
1209 // and optionally calculate number of string keys (keycount)
1210 // or set keycount to zero:
1211 keycount = 0;
1212 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
1213 // if type of table is undetermined,
1214 // iterate over all keys:
1215 for (lua_pushnil(L); lua_next(L, json_export_value_idx); lua_pop(L, 1)) {
1216 switch (lua_type(L, -2)) {
1217 case LUA_TSTRING:
1218 // for string keys,
1219 // increase keycount (may avoid another iteration):
1220 keycount++;
1221 // if type of table was unknown, then type of table is a JSON object now:
1222 if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_OBJECT;
1223 // if type of table was a JSON array, then the type of table is ambiguous now
1224 // and an error is thrown:
1225 else if (tabletype == JSON_TABLETYPE_ARRAY) goto json_export_tabletype_error;
1226 break;
1227 case LUA_TNUMBER:
1228 // for numeric keys,
1229 // if type of table was unknown, then type of table is a JSON array now:
1230 if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_ARRAY;
1231 // if type of table was a JSON object, then the type of table is ambiguous now
1232 // and an error is thrown:
1233 else if (tabletype == JSON_TABLETYPE_OBJECT) goto json_export_tabletype_error;
1234 break;
1235 }
1236 }
1237 }
1238 // raise error if too many nested levels:
1239 if (level >= JSON_MAXDEPTH) {
1240 return luaL_error(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
1241 }
1242 // store previous container information (if existent) on stack swap
1243 // and increase level variable:
1244 if (level++) {
1245 lua_pushvalue(L, json_export_luacontainer_idx);
1246 lua_rawseti(L, json_export_stackswap_idx, ++stackswapidx);
1247 lua_pushvalue(L, json_export_ccontainer_idx);
1248 lua_rawseti(L, json_export_stackswap_idx, ++stackswapidx);
1249 }
1250 // use value as current container:
1251 lua_pushvalue(L, json_export_value_idx);
1252 lua_replace(L, json_export_luacontainer_idx);
1253 // distinguish between JSON objects and JSON arrays:
1254 switch (tabletype) {
1255 // JSON object:
1256 case JSON_TABLETYPE_OBJECT:
1257 // calculate count of string keys unless it has been calculated before:
1258 if (!keycount) {
1259 for (lua_pushnil(L); lua_next(L, json_export_luacontainer_idx); lua_pop(L, 1)) {
1260 if (lua_type(L, -2) == LUA_TSTRING) keycount++;
1261 }
1262 }
1263 // allocate memory for C structure containing string keys and container iteration state:
1264 container = lua_newuserdata(L, sizeof(json_container_t) + (keycount-1) * sizeof(json_key_t));
1265 // store reference to C structure on designated stack position:
1266 lua_replace(L, json_export_ccontainer_idx);
1267 // initialize C structure for container state:
1268 container->type = JSON_TABLETYPE_OBJECT;
1269 container->count = keycount;
1270 container->pos = 0;
1271 // check if object contains any keys:
1272 if (keycount) {
1273 // if yes,
1274 // copy all string keys to the C structure (and reset container->pos again):
1275 for (lua_pushnil(L); lua_next(L, json_export_luacontainer_idx); lua_pop(L, 1)) {
1276 if (lua_type(L, -2) == LUA_TSTRING) {
1277 json_key_t *key = &container->keys[container->pos++];
1278 key->data = lua_tolstring(L, -2, &key->length);
1279 }
1280 }
1281 container->pos = 0;
1282 // sort C array using quicksort:
1283 qsort(container->keys, keycount, sizeof(json_key_t), (void *)json_key_cmp);
1284 }
1285 // add opening bracket to output buffer:
1286 luaL_addchar(&buf, '{');
1287 break;
1288 // JSON array:
1289 case JSON_TABLETYPE_ARRAY:
1290 // allocate memory for C structure for container iteration state:
1291 container = lua_newuserdata(L, sizeof(json_container_t) - sizeof(json_key_t));
1292 // store reference to C structure on designated stack position:
1293 lua_replace(L, json_export_ccontainer_idx);
1294 // initialize C structure for container state:
1295 container->type = JSON_TABLETYPE_ARRAY;
1296 container->pos = 0;
1297 // add opening bracket to output buffer:
1298 luaL_addchar(&buf, '[');
1299 break;
1300 default:
1301 // throw error if table type is unknown:
1302 json_export_tabletype_error:
1303 return luaL_error(L, "JSON export not possible for ambiguous table (cannot decide whether it is an object or array)");
1304 }
1305 break;
1306 default:
1307 // all other datatypes are considered an error:
1308 return luaL_error(L, "JSON export not possible for values of type \"%s\"", lua_typename(L, lua_type(L, json_export_value_idx)));
1309 }
1310 // check if a container is being processed:
1311 if (container) {
1312 // if yes,
1313 // execute code for container iteration:
1314 json_export_container:
1315 // distinguish between JSON objects and JSON arrays:
1316 switch (container->type) {
1317 // JSON object:
1318 case JSON_TABLETYPE_OBJECT:
1319 // finish iteration if all string keys have been processed:
1320 if (container->pos == container->count) goto json_export_close;
1321 // push current string key on top of stack:
1322 key = &container->keys[container->pos];
1323 lua_pushlstring(L, key->data, key->length);
1324 // check if the key has already been exported:
1325 if (!containerkey) {
1326 // if no,
1327 // add a comma to the output buffer if necessary:
1328 if (container->pos) luaL_addchar(&buf, ',');
1329 // set containerkey variable to true:
1330 containerkey = 1;
1331 } else {
1332 // if a key has already been exported,
1333 // add a colon to the output buffer:
1334 luaL_addchar(&buf, ':');
1335 // add a space to the output buffer for pretty results:
1336 if (pretty) luaL_addchar(&buf, ' ');
1337 // replace string key on top of stack with corresponding value:
1338 lua_rawget(L, json_export_luacontainer_idx);
1339 // reset containerkey variable
1340 containerkey = 0;
1341 // increase number of processed key value pairs:
1342 container->pos++;
1343 }
1344 // store key or value on top of stack in designated stack position:
1345 lua_replace(L, json_export_value_idx);
1346 break;
1347 // JSON array:
1348 case JSON_TABLETYPE_ARRAY:
1349 // store next value in designated stack position:
1350 lua_rawgeti(L, json_export_luacontainer_idx, container->pos+1);
1351 lua_replace(L, json_export_value_idx);
1352 // finish iteration if value is nil:
1353 if (lua_isnil(L, json_export_value_idx)) goto json_export_close;
1354 // add a comma to the output buffer if necessary:
1355 if (container->pos) luaL_addchar(&buf, ',');
1356 // increase number of processed values:
1357 container->pos++;
1358 break;
1359 // common code for closing JSON objects or JSON arrays:
1360 json_export_close:
1361 // decrement level variable:
1362 level--;
1363 // handle indentation for pretty results:
1364 if (pretty && container->pos) {
1365 luaL_addchar(&buf, '\n');
1366 for (i=0; i<level; i++) {
1367 lua_pushvalue(L, json_export_indentstring_idx);
1368 luaL_addvalue(&buf);
1369 }
1370 }
1371 // add closing bracket to output buffer:
1372 luaL_addchar(&buf, container->type == JSON_TABLETYPE_OBJECT ? '}' : ']');
1373 // finish export if last level has been closed:
1374 if (!level) goto json_export_finish;
1375 // otherwise,
1376 // recall previous container information from stack swap
1377 // and set C pointer to corresponding C struct:
1378 lua_rawgeti(L, json_export_stackswap_idx, stackswapidx--);
1379 lua_replace(L, json_export_ccontainer_idx);
1380 container = lua_touserdata(L, json_export_ccontainer_idx);
1381 lua_rawgeti(L, json_export_stackswap_idx, stackswapidx--);
1382 lua_replace(L, json_export_luacontainer_idx);
1383 // repeat code for container iteration:
1384 goto json_export_container;
1385 }
1386 // handle indentation for pretty results:
1387 if (pretty && (containerkey || container->type == JSON_TABLETYPE_ARRAY)) {
1388 luaL_addchar(&buf, '\n');
1389 for (i=0; i<level; i++) {
1390 lua_pushvalue(L, json_export_indentstring_idx);
1391 luaL_addvalue(&buf);
1392 }
1393 }
1394 } else {
1395 // if no container is being processed,
1396 // finish export:
1397 json_export_finish:
1398 // for pretty results, add final newline character if outermost container is processed:
1399 if (pretty) luaL_addchar(&buf, '\n');
1400 // create and return Lua string from buffer contents
1401 luaL_pushresult(&buf);
1402 return 1;
1403 }
1404 }
1405 }
1407 // functions in library module:
1408 static const struct luaL_Reg json_module_functions[] = {
1409 {"object", json_object},
1410 {"array", json_array},
1411 {"import", json_import},
1412 {"export", json_export},
1413 {"get", json_get},
1414 {"type", json_type},
1415 {"set", json_set},
1416 {NULL, NULL}
1417 };
1419 // metamethods for JSON objects, JSON arrays, and unknown JSON collections (object or array):
1420 static const struct luaL_Reg json_metatable_functions[] = {
1421 {"__len", json_len},
1422 {"__index", json_index},
1423 {"__newindex", json_newindex},
1424 {"__pairs", json_pairs},
1425 {"__ipairs", json_ipairs},
1426 {"__tostring", json_export},
1427 {NULL, NULL}
1428 };
1430 // metamethods for JSON null marker:
1431 static const struct luaL_Reg json_nullmark_metamethods[] = {
1432 {"__tostring", json_nullmark_tostring},
1433 {NULL, NULL}
1434 };
1436 // initializes json library:
1437 int luaopen_json(lua_State *L) {
1438 // empty stack:
1439 lua_settop(L, 0);
1440 // push library module onto stack position 1:
1441 lua_newtable(L);
1442 // register library functions:
1443 luaL_setfuncs(L, json_module_functions, 0);
1444 // create and store objectmt:
1445 lua_newtable(L);
1446 luaL_setfuncs(L, json_metatable_functions, 0);
1447 json_regstore(L, objectmt);
1448 // create and store arraymt:
1449 lua_newtable(L);
1450 luaL_setfuncs(L, json_metatable_functions, 0);
1451 json_regstore(L, arraymt);
1452 // set metatable of null marker and make it available through library module:
1453 json_pushnullmark(L);
1454 lua_newtable(L);
1455 luaL_setfuncs(L, json_nullmark_metamethods, 0);
1456 lua_setmetatable(L, -2);
1457 lua_setfield(L, 1, "null");
1458 // return library module (that's expected on top of stack):
1459 return 1;
1460 }