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view libraries/json/json.c @ 174:070edea2a92f
Bugfix in json.object and json.array functions: use null-marker for nil values
| author | jbe |
|---|---|
| date | Fri Aug 01 20:29:30 2014 +0200 (2014-08-01) |
| parents | f417c4b607ed |
| children | 20e393d2e6e1 |
line source
1 #include <lua.h>
2 #include <lauxlib.h>
3 #include <stdlib.h>
4 #include <string.h>
5 #include <math.h>
7 // maximum number of nested JSON values (objects and arrays):
8 // NOTE: The Lua reference states that the stack may typically contain at least
9 // "a few thousand elements". Since every nested level consumes
10 // 3 elements on the Lua stack (the object/array, its shadow table,
11 // a string key or a placeholder), we limit the number of nested levels
12 // to 500. If a stack overflow would still happen in the import function,
13 // this is detected nevertheless and an error is thrown (instead of
14 // returning nil and an error string).
15 #define JSON_MAXDEPTH 500
17 // generate dummy memory addresses that represents null values:
18 char json_nullmark;
19 #define json_isnullmark(L, i) (lua_touserdata((L), (i)) == &json_nullmark)
20 #define json_pushnullmark(L) lua_pushlightuserdata((L), &json_nullmark)
22 // macros for usage of Lua registry:
23 #define JSON_REGENT char
24 #define JSON_REGPOINTER void *
25 #define json_regpointer(x) (&json_registry.x)
26 #define json_regfetchpointer(L, x) lua_rawgetp((L), LUA_REGISTRYINDEX, (x))
27 #define json_regfetch(L, x) json_regfetchpointer(L, json_regpointer(x))
28 #define json_regstore(L, x) lua_rawsetp(L, LUA_REGISTRYINDEX, json_regpointer(x))
30 // generate dummy memory addresses that represent Lua objects
31 // via lightuserdata keys and LUA_REGISTRYINDEX:
32 static struct {
33 JSON_REGENT shadowtbl; // ephemeron table that maps tables to their corresponding shadow table
34 JSON_REGENT objectmt; // metatable for JSON objects
35 JSON_REGENT arraymt; // metatable for JSON arrays
36 } json_registry;
38 // returns the string "<JSON null marker>":
39 static int json_nullmark_tostring(lua_State *L) {
40 lua_pushliteral(L, "<JSON null marker>");
41 return 1;
42 }
44 #define json_convert_source_idx 1
45 #define json_convert_iterator_idx 2
46 #define json_convert_output_idx 3
47 #define json_convert_shadow_idx 4
48 #define json_convert_iterfun_idx 5
49 #define json_convert_itertbl_idx 6
51 // converts a Lua table to a JSON object or JSON array:
52 // (does never modify the argument, returns an empty object or array if argument is nil)
53 static int json_convert(lua_State *L, int array) {
54 int arrayidx = 0;
55 // determine is argument is given:
56 if (lua_isnoneornil(L, json_convert_source_idx)) {
57 // if no argument is given (or if argument is nil),
58 // create table with shadow table, and leave first table on top of stack:
59 json_regfetch(L, shadowtbl);
60 lua_newtable(L);
61 lua_pushvalue(L, -1);
62 lua_newtable(L);
63 lua_rawset(L, -4);
64 } else {
65 // if an argument was given,
66 // push its iterator function on stack position 2 if existent,
67 // else push null for normal tables:
68 lua_settop(L, 1);
69 if (lua_getmetatable(L, json_convert_source_idx)) {
70 lua_getfield(L, -1, array ? "__ipairs" : "__pairs");
71 if (lua_isnil(L, -1)) luaL_checktype(L, 1, LUA_TTABLE);
72 else if (lua_type(L, -1) != LUA_TFUNCTION)
73 return luaL_error(L, "%s metamethod is not a function", array ? "__ipairs" : "__pairs");
74 lua_replace(L, -2);
75 } else {
76 lua_pushnil(L);
77 }
78 // create result table on stack position 3:
79 lua_newtable(L);
80 // create shadow table on stack position 4:
81 json_regfetch(L, shadowtbl);
82 lua_newtable(L);
83 lua_pushvalue(L, json_convert_output_idx);
84 lua_pushvalue(L, -2);
85 lua_rawset(L, -4);
86 lua_replace(L, -2);
87 // check if iterator function exists:
88 if (lua_isnil(L, json_convert_iterator_idx)) {
89 // if there is no iterator function,
90 // distinguish between objects and arrays:
91 if (array == 0) {
92 // for an object, copy all string key value pairs to shadow table:
93 for (lua_pushnil(L); lua_next(L, json_convert_source_idx); lua_pop(L, 1)) {
94 if (lua_type(L, -2) == LUA_TSTRING) {
95 lua_pushvalue(L, -2);
96 lua_pushvalue(L, -2);
97 lua_rawset(L, json_convert_shadow_idx);
98 }
99 }
100 } else {
101 // for an array, copy consecutive integer value pairs to shadow table:
102 while (1) {
103 // TODO: Lua 5.3 may support more elements
104 if (arrayidx == INT_MAX) {
105 lua_pushnumber(L, (size_t)INT_MAX+1);
106 lua_rawget(L, json_convert_source_idx);
107 if (lua_isnil(L, -1)) break;
108 return luaL_error(L, "Array exceeded length of %d elements", INT_MAX);
109 }
110 arrayidx++;
111 lua_rawgeti(L, json_convert_source_idx, arrayidx);
112 if (lua_isnil(L, -1)) break;
113 lua_rawseti(L, json_convert_shadow_idx, arrayidx);
114 }
115 }
116 } else {
117 // if there is an iterator function,
118 // call iterator function with source value (first argument)
119 // and store 3 result values on stack positions 5 through 7:
120 lua_pushvalue(L, json_convert_iterator_idx);
121 lua_pushvalue(L, 1);
122 lua_call(L, 1, 3);
123 // iterate through key value pairs and store them in shadow table
124 // while replacing nil values with null-marker:
125 while (1) {
126 lua_pushvalue(L, json_convert_iterfun_idx);
127 lua_pushvalue(L, json_convert_itertbl_idx);
128 lua_pushvalue(L, -3);
129 lua_remove(L, -4);
130 lua_call(L, 2, 2);
131 if (lua_isnil(L, -2)) break;
132 if (lua_type(L, -2) == (array ? LUA_TNUMBER : LUA_TSTRING)) {
133 lua_pushvalue(L, -2);
134 if (lua_isnil(L, -2)) json_pushnullmark(L);
135 else lua_pushvalue(L, -2);
136 lua_rawset(L, json_convert_shadow_idx);
137 }
138 lua_pop(L, 1);
139 }
140 }
141 // let result table be on top of stack:
142 lua_settop(L, json_convert_output_idx);
143 }
144 // set metatable (for result table on top of stack):
145 if (array == 0) json_regfetch(L, objectmt);
146 else json_regfetch(L, arraymt);
147 lua_setmetatable(L, -2);
148 // return table on top of stack:
149 return 1;
150 }
152 static int json_object(lua_State *L) {
153 return json_convert(L, 0);
154 }
156 static int json_array(lua_State *L) {
157 return json_convert(L, 1);
158 }
160 // internal states of JSON parser:
161 #define JSON_STATE_VALUE 0
162 #define JSON_STATE_OBJECT_KEY 1
163 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
164 #define JSON_STATE_OBJECT_VALUE 3
165 #define JSON_STATE_OBJECT_SEPARATOR 4
166 #define JSON_STATE_ARRAY_VALUE 5
167 #define JSON_STATE_ARRAY_SEPARATOR 6
168 #define JSON_STATE_END 7
170 // special Lua stack indicies for json_import function:
171 #define json_import_objectmt_idx 2
172 #define json_import_arraymt_idx 3
173 #define json_import_shadowtbl_idx 4
175 // macros for hex decoding:
176 #define json_utf16_surrogate(x) ((x) >= 0xD800 && (x) <= 0xDFFF)
177 #define json_utf16_lead(x) ((x) >= 0xD800 && (x) <= 0xDBFF)
178 #define json_utf16_tail(x) ((x) >= 0xDC00 && (x) <= 0xDFFF)
179 #define json_import_readhex(x) \
180 do { \
181 x = 0; \
182 for (i=0; i<4; i++) { \
183 x <<= 4; \
184 c = str[pos++]; \
185 if (c >= '0' && c <= '9') x += c - '0'; \
186 else if (c >= 'A' && c <= 'F') x += c - 'A' + 10; \
187 else if (c >= 'a' && c <= 'f') x += c - 'a' + 10; \
188 else if (c == 0) goto json_import_unexpected_eof; \
189 else goto json_import_unexpected_escape; \
190 } \
191 } while (0)
193 // decodes a JSON document:
194 static int json_import(lua_State *L) {
195 int i; // loop variable
196 const char *str; // string to parse
197 size_t total; // total length of string to parse
198 size_t pos = 0; // current position in string to parse
199 size_t level = 0; // nested levels of objects/arrays currently being processed
200 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
201 unsigned char c; // variable to store a single character to be processed (unsigned!)
202 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
203 char *cbuf; // C buffer to decode JSON string values
204 size_t outlen; // maximum length or write position of C buffer
205 long codepoint; // decoded UTF-16 character or higher codepoint
206 long utf16tail; // second decoded UTF-16 character (surrogate tail)
207 size_t arraylen; // variable to temporarily store the array length
208 // require string as argument and convert to C string with length information:
209 str = luaL_checklstring(L, 1, &total);
210 // if string contains a NULL byte, this is a syntax error
211 if (strlen(str) != total) goto json_import_syntax_error;
212 // stack shall contain one function argument:
213 lua_settop(L, 1);
214 // push objectmt onto stack position 2:
215 json_regfetch(L, objectmt);
216 // push arraymt onto stack position 3:
217 json_regfetch(L, arraymt);
218 // push shadowtbl onto stack position 4:
219 json_regfetch(L, shadowtbl);
220 // main loop of parser:
221 json_import_loop:
222 // skip whitespace and store next character in variable 'c':
223 while (c = str[pos],
224 c == ' ' ||
225 c == '\f' ||
226 c == '\n' ||
227 c == '\r' ||
228 c == '\t' ||
229 c == '\v'
230 ) pos++;
231 // NOTE: variable c needs to be unsigned in the following code
232 // switch statement to handle certain (single) characters:
233 switch (c) {
234 // handle end of JSON document:
235 case 0:
236 // if end of JSON document was expected, then return top element of stack as result:
237 if (mode == JSON_STATE_END) return 1;
238 // otherwise, the JSON document was malformed:
239 if (level == 0) {
240 lua_pushnil(L);
241 lua_pushliteral(L, "Empty string");
242 } else {
243 json_import_unexpected_eof:
244 lua_pushnil(L);
245 lua_pushliteral(L, "Unexpected end of JSON document");
246 }
247 return 2;
248 // new JSON object:
249 case '{':
250 // if a JSON object is not expected here, then return an error:
251 if (
252 mode != JSON_STATE_VALUE &&
253 mode != JSON_STATE_OBJECT_VALUE &&
254 mode != JSON_STATE_ARRAY_VALUE
255 ) goto json_import_syntax_error;
256 // create JSON object on stack:
257 lua_newtable(L);
258 // set metatable of JSON object:
259 lua_pushvalue(L, json_import_objectmt_idx);
260 lua_setmetatable(L, -2);
261 // create internal shadow table on stack:
262 lua_newtable(L);
263 // register internal shadow table:
264 lua_pushvalue(L, -2);
265 lua_pushvalue(L, -2);
266 lua_rawset(L, json_import_shadowtbl_idx);
267 // expect object key (or end of object) to follow:
268 mode = JSON_STATE_OBJECT_KEY;
269 // jump to common code for opening JSON object and JSON array:
270 goto json_import_open;
271 // new JSON array:
272 case '[':
273 // if a JSON array is not expected here, then return an error:
274 if (
275 mode != JSON_STATE_VALUE &&
276 mode != JSON_STATE_OBJECT_VALUE &&
277 mode != JSON_STATE_ARRAY_VALUE
278 ) goto json_import_syntax_error;
279 // create JSON array on stack:
280 lua_newtable(L);
281 // set metatable of JSON array:
282 lua_pushvalue(L, json_import_arraymt_idx);
283 lua_setmetatable(L, -2);
284 // create internal shadow table on stack:
285 lua_newtable(L);
286 // register internal shadow table:
287 lua_pushvalue(L, -2);
288 lua_pushvalue(L, -2);
289 lua_rawset(L, json_import_shadowtbl_idx);
290 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
291 lua_pushnil(L);
292 // expect array value (or end of array) to follow:
293 mode = JSON_STATE_ARRAY_VALUE;
294 // continue with common code for opening JSON object and JSON array:
295 // common code for opening JSON object or JSON array:
296 json_import_open:
297 // limit nested levels:
298 if (level >= JSON_MAXDEPTH) {
299 lua_pushnil(L);
300 lua_pushfstring(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
301 return 2;
302 }
303 // additional buffer overflow protection:
304 if (!lua_checkstack(L, LUA_MINSTACK))
305 return luaL_error(L, "Caught stack overflow in JSON import function (too many nested levels and stack size too small)");
306 // increment level:
307 level++;
308 // consume input character:
309 pos++;
310 goto json_import_loop;
311 // end of JSON object:
312 case '}':
313 // if end of JSON object is not expected here, then return an error:
314 if (
315 mode != JSON_STATE_OBJECT_KEY &&
316 mode != JSON_STATE_OBJECT_SEPARATOR
317 ) goto json_import_syntax_error;
318 // jump to common code for end of JSON object and JSON array:
319 goto json_import_close;
320 // end of JSON array:
321 case ']':
322 // if end of JSON array is not expected here, then return an error:
323 if (
324 mode != JSON_STATE_ARRAY_VALUE &&
325 mode != JSON_STATE_ARRAY_SEPARATOR
326 ) goto json_import_syntax_error;
327 // pop nil key/magic (that was needed to keep stack balance):
328 lua_pop(L, 1);
329 // continue with common code for end of JSON object and JSON array:
330 // common code for end of JSON object or JSON array:
331 json_import_close:
332 // consume input character:
333 pos++;
334 // pop shadow table:
335 lua_pop(L, 1);
336 // check if nested:
337 if (--level) {
338 // if nested,
339 // check if outer(!) structure is an array or object:
340 if (lua_isnil(L, -2)) {
341 // select array value processing:
342 mode = JSON_STATE_ARRAY_VALUE;
343 } else {
344 // select object value processing:
345 mode = JSON_STATE_OBJECT_VALUE;
346 }
347 // store value in outer structure:
348 goto json_import_process_value;
349 }
350 // if not nested, then expect end of JSON document and continue with loop:
351 mode = JSON_STATE_END;
352 goto json_import_loop;
353 // key terminator:
354 case ':':
355 // if key terminator is not expected here, then return an error:
356 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
357 goto json_import_syntax_error;
358 // consume input character:
359 pos++;
360 // expect object value to follow:
361 mode = JSON_STATE_OBJECT_VALUE;
362 // continue with loop:
363 goto json_import_loop;
364 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
365 case ',':
366 // branch according to parser state:
367 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
368 // expect an object key to follow:
369 mode = JSON_STATE_OBJECT_KEY;
370 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
371 // expect an array value to follow:
372 mode = JSON_STATE_ARRAY_VALUE;
373 } else {
374 // if value terminator is not expected here, then return an error:
375 goto json_import_syntax_error;
376 }
377 // consume input character:
378 pos++;
379 // continue with loop:
380 goto json_import_loop;
381 // string literal:
382 case '"':
383 // consume quote character:
384 pos++;
385 // find last character in input string:
386 outlen = pos;
387 while ((c = str[outlen]) != '"') {
388 // consume one character:
389 outlen++;
390 // handle unexpected end of JSON document:
391 if (c == 0) goto json_import_unexpected_eof;
392 // consume one extra character when encountering an escaped quote:
393 else if (c == '\\' && str[outlen] == '"') outlen++;
394 }
395 // determine buffer length:
396 outlen -= pos;
397 // check if string is non empty:
398 if (outlen) {
399 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
400 cbuf = luaL_buffinitsize(L, &luabuf, outlen);
401 outlen = 0;
402 // loop through the characters until encountering end quote:
403 while ((c = str[pos++]) != '"') {
404 // NOTE: unexpected end cannot happen anymore
405 if (c < 32 || c == 127) {
406 // do not allow ASCII control characters:
407 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
408 // by this parser to allow different encodings than Unicode
409 lua_pushnil(L);
410 lua_pushliteral(L, "Unexpected control character in JSON string");
411 return 2;
412 } else if (c == '\\') {
413 // read next char after backslash escape:
414 c = str[pos++];
415 switch (c) {
416 // unexpected end-of-string:
417 case 0:
418 goto json_import_unexpected_eof;
419 // unescaping of quotation mark, slash, and backslash:
420 case '"':
421 case '/':
422 case '\\':
423 cbuf[outlen++] = c;
424 break;
425 // unescaping of backspace:
426 case 'b': cbuf[outlen++] = '\b'; break;
427 // unescaping of form-feed:
428 case 'f': cbuf[outlen++] = '\f'; break;
429 // unescaping of new-line:
430 case 'n': cbuf[outlen++] = '\n'; break;
431 // unescaping of carriage-return:
432 case 'r': cbuf[outlen++] = '\r'; break;
433 // unescaping of tabulator:
434 case 't': cbuf[outlen++] = '\t'; break;
435 // unescaping of UTF-16 characters
436 case 'u':
437 // decode 4 hex nibbles:
438 json_import_readhex(codepoint);
439 // handle surrogate character:
440 if (json_utf16_surrogate(codepoint)) {
441 // check if first surrogate is in valid range:
442 if (json_utf16_lead(codepoint)) {
443 // require second surrogate:
444 if ((c = str[pos++]) != '\\' || (c = str[pos++]) != 'u') {
445 if (c == 0) goto json_import_unexpected_eof;
446 else goto json_import_wrong_surrogate;
447 }
448 // read 4 hex nibbles of second surrogate character:
449 json_import_readhex(utf16tail);
450 // check if second surrogate is in valid range:
451 if (!json_utf16_tail(utf16tail)) goto json_import_wrong_surrogate;
452 // calculate codepoint:
453 codepoint = 0x10000 + (utf16tail - 0xDC00) + (codepoint - 0xD800) * 0x400;
454 } else {
455 // throw error for wrong surrogates:
456 json_import_wrong_surrogate:
457 lua_pushnil(L);
458 lua_pushliteral(L, "Illegal UTF-16 surrogate in JSON string escape sequence");
459 return 2;
460 }
461 }
462 // encode as UTF-8:
463 if (codepoint < 0x80) {
464 cbuf[outlen++] = (char)codepoint;
465 } else if (codepoint < 0x800) {
466 cbuf[outlen++] = (char)(0xc0 | (codepoint >> 6));
467 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
468 } else if (codepoint < 0x10000) {
469 cbuf[outlen++] = (char)(0xe0 | (codepoint >> 12));
470 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 6) & 0x3f));
471 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
472 } else {
473 cbuf[outlen++] = (char)(0xf0 | (codepoint >> 18));
474 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 12) & 0x3f));
475 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 6) & 0x3f));
476 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
477 }
478 break;
479 // unexpected escape sequence:
480 default:
481 json_import_unexpected_escape:
482 lua_pushnil(L);
483 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
484 return 2;
485 }
486 } else {
487 // normal character:
488 cbuf[outlen++] = c;
489 }
490 }
491 // process buffer to Lua string:
492 luaL_pushresultsize(&luabuf, outlen);
493 } else {
494 // if JSON string is empty,
495 // push empty Lua string:
496 lua_pushliteral(L, "");
497 // consume closing quote:
498 pos++;
499 }
500 // continue with processing of decoded string:
501 goto json_import_process_value;
502 }
503 // process values whose type is is not deducible from a single character:
504 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
505 // for numbers,
506 // use strtod() call to parse a (double precision) floating point number:
507 double numval;
508 char *endptr;
509 numval = strtod(str+pos, &endptr);
510 // catch parsing errors:
511 if (endptr == str+pos) goto json_import_syntax_error;
512 // consume characters that were parsed:
513 pos += endptr - (str+pos);
514 // push parsed (double precision) floating point number on Lua stack:
515 lua_pushnumber(L, numval);
516 } else if (!strncmp(str+pos, "true", 4)) {
517 // consume 4 input characters for "true":
518 pos += 4;
519 // put Lua true value onto stack:
520 lua_pushboolean(L, 1);
521 } else if (!strncmp(str+pos, "false", 5)) {
522 // consume 5 input characters for "false":
523 pos += 5;
524 // put Lua false value onto stack:
525 lua_pushboolean(L, 0);
526 } else if (!strncmp(str+pos, "null", 4)) {
527 // consume 4 input characters for "null":
528 pos += 4;
529 // different behavor for top-level and sub-levels:
530 if (level) {
531 // if sub-level,
532 // push special null-marker onto stack:
533 json_pushnullmark(L);
534 } else {
535 // if top-level,
536 // push nil onto stack:
537 lua_pushnil(L);
538 }
539 } else {
540 // all other cases are a syntax error:
541 goto json_import_syntax_error;
542 }
543 // process a decoded value or key value pair (expected on top of Lua stack):
544 json_import_process_value:
545 switch (mode) {
546 // an object key has been read:
547 case JSON_STATE_OBJECT_KEY:
548 // if an object key is not a string, then this is a syntax error:
549 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
550 // expect key terminator to follow:
551 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
552 // continue with loop:
553 goto json_import_loop;
554 // a key value pair has been read:
555 case JSON_STATE_OBJECT_VALUE:
556 // store key value pair in outer shadow table:
557 lua_rawset(L, -3);
558 // expect value terminator (or end of object) to follow:
559 mode = JSON_STATE_OBJECT_SEPARATOR;
560 // continue with loop:
561 goto json_import_loop;
562 // an array value has been read:
563 case JSON_STATE_ARRAY_VALUE:
564 // get current array length:
565 arraylen = lua_rawlen(L, -3);
566 // throw error if array would exceed INT_MAX elements:
567 // TODO: Lua 5.3 may support more elements
568 if (arraylen >= INT_MAX) {
569 lua_pushnil(L);
570 lua_pushfstring(L, "Array exceeded length of %d elements", INT_MAX);
571 }
572 // store value in outer shadow table:
573 lua_rawseti(L, -3, arraylen + 1);
574 // expect value terminator (or end of object) to follow:
575 mode = JSON_STATE_ARRAY_SEPARATOR;
576 // continue with loop
577 goto json_import_loop;
578 // a single value has been read:
579 case JSON_STATE_VALUE:
580 // leave value on top of stack, expect end of JSON document, and continue with loop:
581 mode = JSON_STATE_END;
582 goto json_import_loop;
583 }
584 // syntax error handling (reachable by goto statement):
585 json_import_syntax_error:
586 lua_pushnil(L);
587 lua_pushliteral(L, "Syntax error in JSON document");
588 return 2;
589 }
591 // special Lua stack indicies for json_path function:
592 #define json_path_shadowtbl_idx 1
594 // stack offset of arguments to json_path function:
595 #define json_path_idxshift 1
597 // gets a value or its type from a JSON document (passed as first argument)
598 // using a path (passed as variable number of keys after first argument):
599 static int json_path(lua_State *L, int type_mode) {
600 int stacktop; // stack index of top of stack (after shifting)
601 int idx = 2 + json_path_idxshift; // stack index of current argument to process
602 // require at least one argument:
603 luaL_checkany(L, 1);
604 // insert shadowtbl into stack at position 1 (shifting the arguments):
605 json_regfetch(L, shadowtbl);
606 lua_insert(L, 1);
607 // store stack index of top of stack:
608 stacktop = lua_gettop(L);
609 // use first argument as "current value" (stored on top of stack):
610 lua_pushvalue(L, 1 + json_path_idxshift);
611 // process each "path key" (2nd argument and following arguments):
612 while (idx <= stacktop) {
613 // if "current value" (on top of stack) is nil, then the path cannot be walked and nil is returned:
614 if (lua_isnil(L, -1)) return 1;
615 // try to get shadow table of "current value":
616 lua_pushvalue(L, -1);
617 lua_rawget(L, json_path_shadowtbl_idx);
618 if (lua_isnil(L, -1)) {
619 // if no shadow table is found,
620 if (lua_type(L, -1) == LUA_TTABLE) {
621 // and if "current value" is a table,
622 // drop nil from stack:
623 lua_pop(L, 1);
624 // get "next value" using the "path key":
625 lua_pushvalue(L, idx++);
626 lua_gettable(L, -2);
627 } else {
628 // if "current value" is not a table,
629 // then the path cannot be walked and nil (already on top of stack) is returned:
630 return 1;
631 }
632 } else {
633 // if a shadow table is found,
634 // set "current value" to its shadow table:
635 lua_replace(L, -2);
636 // get "next value" using the "path key":
637 lua_pushvalue(L, idx++);
638 lua_rawget(L, -2);
639 }
640 // the "next value" replaces the "current value":
641 lua_replace(L, -2);
642 }
643 if (!type_mode) {
644 // if a value (and not its type) was requested,
645 // check if value is the null-marker, and store nil on top of Lua stack in that case:
646 if (json_isnullmark(L, -1)) lua_pushnil(L);
647 } else {
648 // if the type was requested,
649 // check if value is the null-marker:
650 if (json_isnullmark(L, -1)) {
651 // if yes, store string "null" on top of Lua stack:
652 lua_pushliteral(L, "null");
653 } else {
654 // otherwise,
655 // check if metatable indicates "object" or "array":
656 if (lua_getmetatable(L, -1)) {
657 json_regfetch(L, objectmt);
658 if (lua_rawequal(L, -2, -1)) {
659 // if value has metatable for JSON objects,
660 // return string "object":
661 lua_pushliteral(L, "object");
662 return 1;
663 }
664 json_regfetch(L, arraymt);
665 if (lua_rawequal(L, -3, -1)) {
666 // if value has metatable for JSON arrays,
667 // return string "object":
668 lua_pushliteral(L, "array");
669 return 1;
670 }
671 // remove 3 metatables (one of the value, two for comparison) from stack:
672 lua_pop(L, 3);
673 }
674 // otherwise, get the Lua type:
675 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
676 }
677 }
678 // return the top most value on the Lua stack:
679 return 1;
680 }
682 // gets a value from a JSON document (passed as first argument)
683 // using a path (passed as variable number of keys after first argument):
684 static int json_get(lua_State *L) {
685 return json_path(L, 0);
686 }
688 // gets a value's type from a JSON document (passed as first argument)
689 // using a path (variable number of keys after first argument):
690 static int json_type(lua_State *L) {
691 return json_path(L, 1);
692 }
694 // special Lua stack indicies for json_set function:
695 #define json_set_shadowtbl_idx 1
696 #define json_set_objectmt_idx 2
697 #define json_set_arraymt_idx 3
699 // stack offset of arguments to json_set function:
700 #define json_set_idxshift 3
702 // sets a value (passed as second argument) in a JSON document (passed as first argument)
703 // using a path (variable number of keys starting at third argument):
704 static int json_set(lua_State *L) {
705 int stacktop; // stack index of top of stack (after shifting)
706 int idx = 3; // stack index of current argument to process
707 // require at least two arguments:
708 luaL_checkany(L, 1);
709 luaL_checkany(L, 2);
710 // insert shadowtbl into stack at position 1 (shifting the arguments):
711 json_regfetch(L, shadowtbl);
712 lua_insert(L, 1);
713 // insert objectmt into stack at position 2 (shifting the arguments):
714 json_regfetch(L, objectmt);
715 lua_insert(L, 2);
716 // insert arraymt into stack at position 3 (shifting the arguments):
717 json_regfetch(L, arraymt);
718 lua_insert(L, 3);
719 // store stack index of top of stack:
720 stacktop = lua_gettop(L);
721 // use nil as initial "parent value":
722 lua_pushnil(L);
723 // use first argument as "current value":
724 lua_pushvalue(L, 1 + json_set_idxshift);
725 // set all necessary values in path:
726 for (idx = 3 + json_set_idxshift; idx<=stacktop; idx++) {
727 // push metatable of "current value" onto stack:
728 if (!lua_getmetatable(L, -1)) lua_pushnil(L);
729 // distinguish according to type of path key:
730 switch (lua_type(L, idx)) {
731 case LUA_TSTRING:
732 // if path key is a string,
733 // check if "current value" is a JSON object (or table without metatable):
734 if (
735 lua_rawequal(L, -1, json_set_objectmt_idx) ||
736 (lua_isnil(L, -1) && lua_type(L, -2) == LUA_TTABLE)
737 ) {
738 // if "current value" is acceptable,
739 // pop metatable and leave "current value" on top of stack:
740 lua_pop(L, 1);
741 } else {
742 // if "current value" is not acceptable:
743 // pop metatable and "current value":
744 lua_pop(L, 2);
745 // throw error if parent element does not exist:
746 if (lua_isnil(L, -1)) return luaL_error(L, "Root element is not a JSON object");
747 // push new JSON object as "current value" onto stack:
748 lua_newtable(L);
749 // create and register shadow table:
750 lua_pushvalue(L, -1);
751 lua_newtable(L);
752 lua_rawset(L, json_set_shadowtbl_idx);
753 // set metatable of JSON object:
754 lua_pushvalue(L, json_set_objectmt_idx);
755 lua_setmetatable(L, -2);
756 // set entry in "parent value":
757 lua_pushvalue(L, idx-1);
758 lua_pushvalue(L, -2);
759 lua_settable(L, -4);
760 }
761 break;
762 case LUA_TNUMBER:
763 // if path key is a number,
764 // check if "current value" is a JSON array (or table without metatable):
765 if (
766 lua_rawequal(L, -1, json_set_arraymt_idx) ||
767 (lua_isnil(L, -1) && lua_type(L, -2) == LUA_TTABLE)
768 ) {
769 // if "current value" is acceptable,
770 // pop metatable and leave "current value" on top of stack:
771 lua_pop(L, 1);
772 } else {
773 // if "current value" is not acceptable:
774 // pop metatable and "current value":
775 lua_pop(L, 2);
776 // throw error if parent element does not exist:
777 if (lua_isnil(L, -1)) return luaL_error(L, "Root element is not a JSON array");
778 // push new JSON array as "current value" onto stack:
779 lua_newtable(L);
780 // create and register shadow table:
781 lua_pushvalue(L, -1);
782 lua_newtable(L);
783 lua_rawset(L, json_set_shadowtbl_idx);
784 // set metatable of JSON array:
785 lua_pushvalue(L, json_set_arraymt_idx);
786 lua_setmetatable(L, -2);
787 // set entry in "parent value":
788 lua_pushvalue(L, idx-1);
789 lua_pushvalue(L, -2);
790 lua_settable(L, -4);
791 }
792 break;
793 default:
794 return luaL_error(L, "Invalid path key of type %s", lua_typename(L, lua_type(L, idx)));
795 }
796 // check if last path element is being processed:
797 if (idx == stacktop) {
798 // if the last path element is being processed,
799 // set last path value in "current value" container:
800 lua_pushvalue(L, idx);
801 lua_pushvalue(L, 2 + json_set_idxshift);
802 lua_settable(L, -3);
803 } else {
804 // if the processed path element is not the last,
805 // use old "current value" as new "parent value"
806 lua_remove(L, -2);
807 // push new "current value" onto stack by performing a lookup:
808 lua_pushvalue(L, idx);
809 lua_gettable(L, -2);
810 }
811 }
812 // return first argument for convenience:
813 lua_settop(L, 1 + json_set_idxshift);
814 return 1;
815 }
817 // returns the length of a JSON array (or zero for a table without numeric keys):
818 static int json_len(lua_State *L) {
819 // stack shall contain one function argument:
820 lua_settop(L, 1);
821 // try to get corresponding shadow table for first argument:
822 json_regfetch(L, shadowtbl);
823 lua_pushvalue(L, 1);
824 lua_rawget(L, -2);
825 // if shadow table does not exist, return length of argument, else length of shadow table:
826 lua_pushnumber(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
827 return 1;
828 }
830 static int json_index(lua_State *L) {
831 // stack shall contain two function arguments:
832 lua_settop(L, 2);
833 // get corresponding shadow table for first argument:
834 json_regfetch(L, shadowtbl);
835 lua_pushvalue(L, 1);
836 lua_rawget(L, -2);
837 // throw error if no shadow table was found:
838 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
839 // use key passed as second argument to lookup value in shadow table:
840 lua_pushvalue(L, 2);
841 lua_rawget(L, -2);
842 // if value is null-marker, then push nil onto stack:
843 if (json_isnullmark(L, -1)) lua_pushnil(L);
844 // return either looked up value, or nil
845 return 1;
846 }
848 static int json_newindex(lua_State *L) {
849 // stack shall contain three function arguments:
850 lua_settop(L, 3);
851 // get corresponding shadow table for first argument:
852 json_regfetch(L, shadowtbl);
853 lua_pushvalue(L, 1);
854 lua_rawget(L, -2);
855 // throw error if no shadow table was found:
856 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
857 // replace first argument with shadow table:
858 lua_replace(L, 1);
859 // reset stack and use second and third argument to write to shadow table:
860 lua_settop(L, 3);
861 lua_rawset(L, 1);
862 // return nothing:
863 return 0;
864 }
866 static int json_pairs_iterfunc(lua_State *L) {
867 // stack shall contain two function arguments:
868 lua_settop(L, 2);
869 // get corresponding shadow table for first argument:
870 json_regfetch(L, shadowtbl);
871 lua_pushvalue(L, 1);
872 lua_rawget(L, -2);
873 // throw error if no shadow table was found:
874 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
875 // get next key value pair from shadow table (using previous key from argument 2)
876 // and return nothing if there is no next pair:
877 lua_pushvalue(L, 2);
878 if (!lua_next(L, -2)) return 0;
879 // replace null-marker with nil:
880 if (json_isnullmark(L, -1)) {
881 lua_pop(L, 1);
882 lua_pushnil(L);
883 }
884 // return key and value (or key and nil, if null-marker was found):
885 return 2;
886 }
888 // returns a triple such that 'for key, value in pairs(obj) do ... end'
889 // iterates through all key value pairs (including JSON null keys represented as Lua nil):
890 static int json_pairs(lua_State *L) {
891 // require one argument to function
892 luaL_checkany(L, 1);
893 // return triple of function json_pairs_iterfunc, first argument, and nil:
894 lua_pushcfunction(L, json_pairs_iterfunc);
895 lua_pushvalue(L, 1);
896 lua_pushnil(L);
897 return 3;
898 }
900 static int json_ipairs_iterfunc(lua_State *L) {
901 lua_Integer idx;
902 // stack shall contain two function arguments:
903 lua_settop(L, 2);
904 // calculate new index by incrementing second argument:
905 idx = lua_tointeger(L, 2) + 1;
906 // get corresponding shadow table for first argument:
907 json_regfetch(L, shadowtbl);
908 lua_pushvalue(L, 1);
909 lua_rawget(L, -2);
910 // throw error if no shadow table was found:
911 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
912 // do integer lookup in shadow table:
913 lua_rawgeti(L, -1, idx);
914 // return nothing if there was no value:
915 if (lua_isnil(L, -1)) return 0;
916 // return new index and
917 // either the looked up value if it is not equal to the null-marker
918 // or nil instead of null-marker:
919 lua_pushinteger(L, idx);
920 if (json_isnullmark(L, -2)) lua_pushnil(L);
921 else lua_pushvalue(L, -2);
922 return 2;
923 }
925 // returns a triple such that 'for idx, value in ipairs(ary) do ... end'
926 // iterates through all values (including JSON null represented as Lua nil):
927 static int json_ipairs(lua_State *L) {
928 // require one argument to function
929 luaL_checkany(L, 1);
930 // return triple of function json_ipairs_iterfunc, first argument, and zero:
931 lua_pushcfunction(L, json_ipairs_iterfunc);
932 lua_pushvalue(L, 1);
933 lua_pushinteger(L, 0);
934 return 3;
935 }
937 typedef struct {
938 size_t length;
939 const char *data;
940 } json_key_t;
942 static int json_key_cmp(json_key_t *key1, json_key_t *key2) {
943 size_t pos = 0;
944 unsigned char c1, c2;
945 while (1) {
946 if (key1->length > pos) {
947 if (key2->length > pos) {
948 c1 = key1->data[pos];
949 c2 = key2->data[pos];
950 if (c1 < c2) return -1;
951 else if (c1 > c2) return 1;
952 } else {
953 return 1;
954 }
955 } else {
956 if (key2->length > pos) {
957 return -1;
958 } else {
959 return 0;
960 }
961 }
962 pos++;
963 }
964 }
966 #define JSON_TABLETYPE_UNKNOWN 0
967 #define JSON_TABLETYPE_OBJECT 1
968 #define JSON_TABLETYPE_ARRAY 2
970 #define json_export_internal_indentstring_idx 1
971 #define json_export_internal_level_idx 2
972 #define json_export_internal_value_idx 3
973 #define json_export_internal_tmp_idx 4
975 static int json_export_internal(lua_State *L) {
976 int level;
977 int pretty;
978 int i;
979 lua_Number num;
980 const char *str;
981 unsigned char c;
982 size_t strlen;
983 size_t pos = 0;
984 luaL_Buffer buf;
985 char hexcode[7]; // backslash, character 'u', 4 hex digits, and terminating NULL byte
986 int tabletype = JSON_TABLETYPE_UNKNOWN;
987 int anyelement = 0;
988 size_t keycount = 0;
989 size_t keypos = 0;
990 json_key_t *keybuf = NULL;
991 lua_Integer idx;
992 lua_settop(L, json_export_internal_value_idx);
993 if (json_isnullmark(L, json_export_internal_value_idx)) {
994 lua_pop(L, 1);
995 lua_pushnil(L);
996 }
997 switch (lua_type(L, json_export_internal_value_idx)) {
998 case LUA_TNIL:
999 lua_pushliteral(L, "null");
1000 return 1;
1001 case LUA_TNUMBER:
1002 num = lua_tonumber(L, json_export_internal_value_idx);
1003 if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
1004 if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
1005 lua_tostring(L, json_export_internal_value_idx);
1006 return 1;
1007 case LUA_TBOOLEAN:
1008 if (lua_toboolean(L, json_export_internal_value_idx)) {
1009 lua_pushliteral(L, "true");
1010 } else {
1011 lua_pushliteral(L, "false");
1012 }
1013 return 1;
1014 case LUA_TSTRING:
1015 str = lua_tolstring(L, 3, &strlen);
1016 luaL_buffinit(L, &buf);
1017 luaL_addchar(&buf, '"');
1018 while (pos < strlen) {
1019 c = str[pos++];
1020 if (c == '"') luaL_addstring(&buf, "\\\"");
1021 else if (c == '\\') luaL_addstring(&buf, "\\\\");
1022 else if (c == 127) luaL_addstring(&buf, "\\u007F");
1023 else if (c >= 32) luaL_addchar(&buf, c);
1024 else if (c == '\b') luaL_addstring(&buf, "\\b");
1025 else if (c == '\f') luaL_addstring(&buf, "\\f");
1026 else if (c == '\n') luaL_addstring(&buf, "\\n");
1027 else if (c == '\r') luaL_addstring(&buf, "\\r");
1028 else if (c == '\t') luaL_addstring(&buf, "\\t");
1029 else if (c == '\v') luaL_addstring(&buf, "\\v");
1030 else {
1031 sprintf(hexcode, "\\u%04X", c);
1032 luaL_addstring(&buf, hexcode);
1033 }
1034 }
1035 luaL_addchar(&buf, '"');
1036 luaL_pushresult(&buf);
1037 return 1;
1038 case LUA_TTABLE:
1039 if (lua_getmetatable(L, json_export_internal_value_idx)) {
1040 json_regfetch(L, objectmt);
1041 if (lua_rawequal(L, -2, -1)) {
1042 tabletype = JSON_TABLETYPE_OBJECT;
1043 } else {
1044 json_regfetch(L, arraymt);
1045 if (lua_rawequal(L, -3, -1)) {
1046 tabletype = JSON_TABLETYPE_ARRAY;
1047 } else {
1048 return luaL_error(L, "JSON export not possible for tables with nonsupported metatable");
1049 }
1050 }
1051 }
1052 json_regfetch(L, shadowtbl);
1053 lua_pushvalue(L, json_export_internal_value_idx);
1054 lua_rawget(L, -2);
1055 if (!lua_isnil(L, -1)) lua_replace(L, json_export_internal_value_idx);
1056 lua_settop(L, json_export_internal_value_idx);
1057 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
1058 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1059 switch (lua_type(L, -2)) {
1060 case LUA_TSTRING:
1061 keycount++;
1062 if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_OBJECT;
1063 else if (tabletype == JSON_TABLETYPE_ARRAY) goto json_export_tabletype_error;
1064 break;
1065 case LUA_TNUMBER:
1066 if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_ARRAY;
1067 else if (tabletype == JSON_TABLETYPE_OBJECT) goto json_export_tabletype_error;
1068 break;
1069 }
1070 }
1071 }
1072 pretty = lua_toboolean(L, json_export_internal_indentstring_idx);
1073 level = lua_tointeger(L, json_export_internal_level_idx) + 1;
1074 if (level > JSON_MAXDEPTH) {
1075 return luaL_error(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
1076 }
1077 switch (tabletype) {
1078 case JSON_TABLETYPE_OBJECT:
1079 if (!keycount) {
1080 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1081 if (lua_type(L, -2) == LUA_TSTRING) keycount++;
1082 }
1083 }
1084 if (keycount) {
1085 keybuf = calloc(keycount, sizeof(json_key_t));
1086 if (!keybuf) return luaL_error(L, "Memory allocation failed in JSON library");
1087 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1088 if (lua_type(L, -2) == LUA_TSTRING) {
1089 json_key_t *key = keybuf + (keypos++);
1090 key->data = lua_tolstring(L, -2, &key->length);
1091 }
1092 }
1093 qsort(keybuf, keycount, sizeof(json_key_t), (void *)json_key_cmp);
1094 }
1095 luaL_buffinit(L, &buf);
1096 luaL_addchar(&buf, '{');
1097 for (keypos=0; keypos<keycount; keypos++) {
1098 json_key_t *key = keybuf + keypos;
1099 if (keypos) luaL_addchar(&buf, ',');
1100 if (pretty) {
1101 luaL_addchar(&buf, '\n');
1102 for (i=0; i<level; i++) {
1103 lua_pushvalue(L, json_export_internal_indentstring_idx);
1104 luaL_addvalue(&buf);
1105 }
1106 }
1107 lua_pushcfunction(L, json_export_internal);
1108 lua_pushvalue(L, json_export_internal_indentstring_idx);
1109 lua_pushinteger(L, level);
1110 lua_pushlstring(L, key->data, key->length);
1111 if (lua_pcall(L, 3, 1, 0)) {
1112 if (keybuf) free(keybuf);
1113 return lua_error(L);
1114 }
1115 luaL_addvalue(&buf);
1116 luaL_addchar(&buf, ':');
1117 if (pretty) luaL_addchar(&buf, ' ');
1118 lua_pushcfunction(L, json_export_internal);
1119 lua_pushvalue(L, json_export_internal_indentstring_idx);
1120 lua_pushinteger(L, level);
1121 lua_pushlstring(L, key->data, key->length);
1122 lua_rawget(L, json_export_internal_value_idx);
1123 if (lua_pcall(L, 3, 1, 0)) {
1124 if (keybuf) free(keybuf);
1125 return lua_error(L);
1126 }
1127 luaL_addvalue(&buf);
1128 }
1129 if (keybuf) free(keybuf);
1130 if (pretty && keycount != 0) {
1131 luaL_addchar(&buf, '\n');
1132 for (i=0; i<level-1; i++) {
1133 lua_pushvalue(L, json_export_internal_indentstring_idx);
1134 luaL_addvalue(&buf);
1135 }
1136 }
1137 luaL_addchar(&buf, '}');
1138 if (pretty && level == 1) luaL_addchar(&buf, '\n');
1139 luaL_pushresult(&buf);
1140 return 1;
1141 case JSON_TABLETYPE_ARRAY:
1142 lua_settop(L, json_export_internal_tmp_idx);
1143 luaL_buffinit(L, &buf);
1144 luaL_addchar(&buf, '[');
1145 for (idx = 1; ; idx++) {
1146 lua_rawgeti(L, json_export_internal_value_idx, idx);
1147 if (lua_isnil(L, -1)) {
1148 lua_pop(L, 1);
1149 break;
1150 }
1151 lua_replace(L, json_export_internal_tmp_idx);
1152 if (anyelement) luaL_addchar(&buf, ',');
1153 anyelement = 1;
1154 if (pretty) {
1155 luaL_addchar(&buf, '\n');
1156 for (i=0; i<level; i++) {
1157 lua_pushvalue(L, json_export_internal_indentstring_idx);
1158 luaL_addvalue(&buf);
1159 }
1160 }
1161 lua_pushcfunction(L, json_export_internal);
1162 lua_pushvalue(L, json_export_internal_indentstring_idx);
1163 lua_pushinteger(L, level);
1164 lua_pushvalue(L, json_export_internal_tmp_idx);
1165 lua_call(L, 3, 1);
1166 luaL_addvalue(&buf);
1167 }
1168 if (pretty && anyelement) {
1169 luaL_addchar(&buf, '\n');
1170 for (i=0; i<level-1; i++) {
1171 lua_pushvalue(L, json_export_internal_indentstring_idx);
1172 luaL_addvalue(&buf);
1173 }
1174 }
1175 luaL_addchar(&buf, ']');
1176 if (pretty && level == 1) luaL_addchar(&buf, '\n');
1177 luaL_pushresult(&buf);
1178 return 1;
1179 }
1180 json_export_tabletype_error:
1181 return luaL_error(L, "JSON export not possible for ambiguous table (cannot decide whether it is an object or array)");
1182 }
1183 return luaL_error(L, "JSON export not possible for values of type \"%s\"", lua_typename(L, lua_type(L, json_export_internal_value_idx)));
1184 }
1186 static int json_export(lua_State *L) {
1187 lua_settop(L, 1);
1188 lua_pushcfunction(L, json_export_internal);
1189 lua_pushnil(L);
1190 lua_pushinteger(L, 0);
1191 lua_pushvalue(L, 1);
1192 lua_call(L, 3, 1);
1193 return 1;
1194 }
1196 static int json_pretty(lua_State *L) {
1197 lua_settop(L, 2);
1198 lua_pushcfunction(L, json_export_internal);
1199 if (lua_isnil(L, 2)) lua_pushliteral(L, " ");
1200 else lua_pushvalue(L, 2);
1201 lua_pushinteger(L, 0);
1202 lua_pushvalue(L, 1);
1203 lua_call(L, 3, 1);
1204 return 1;
1205 }
1207 // functions in library module:
1208 static const struct luaL_Reg json_module_functions[] = {
1209 {"object", json_object},
1210 {"array", json_array},
1211 {"import", json_import},
1212 {"export", json_export},
1213 {"pretty", json_pretty},
1214 {"get", json_get},
1215 {"type", json_type},
1216 {"set", json_set},
1217 {NULL, NULL}
1218 };
1220 // metamethods for JSON objects, JSON arrays, and unknown JSON collections (object or array):
1221 static const struct luaL_Reg json_metatable_functions[] = {
1222 {"__len", json_len},
1223 {"__index", json_index},
1224 {"__newindex", json_newindex},
1225 {"__pairs", json_pairs},
1226 {"__ipairs", json_ipairs},
1227 {"__tostring", json_export},
1228 {NULL, NULL}
1229 };
1231 // metamethods for JSON null marker:
1232 static const struct luaL_Reg json_nullmark_metamethods[] = {
1233 {"__tostring", json_nullmark_tostring},
1234 {NULL, NULL}
1235 };
1237 // initializes json library:
1238 int luaopen_json(lua_State *L) {
1239 // empty stack:
1240 lua_settop(L, 0);
1241 // push library module onto stack position 1:
1242 lua_newtable(L);
1243 // register library functions:
1244 luaL_setfuncs(L, json_module_functions, 0);
1245 // create and store objectmt:
1246 lua_newtable(L);
1247 luaL_setfuncs(L, json_metatable_functions, 0);
1248 json_regstore(L, objectmt);
1249 // create and store arraymt:
1250 lua_newtable(L);
1251 luaL_setfuncs(L, json_metatable_functions, 0);
1252 json_regstore(L, arraymt);
1253 // create and store ephemeron table to store shadow tables for each JSON object/array
1254 // to allow NULL values returned as nil
1255 lua_newtable(L);
1256 lua_newtable(L); // metatable for ephemeron table
1257 lua_pushliteral(L, "__mode");
1258 lua_pushliteral(L, "k");
1259 lua_rawset(L, -3);
1260 lua_setmetatable(L, -2);
1261 json_regstore(L, shadowtbl);
1262 // set metatable of null marker and make it available through library module:
1263 json_pushnullmark(L);
1264 lua_newtable(L);
1265 luaL_setfuncs(L, json_nullmark_metamethods, 0);
1266 lua_setmetatable(L, -2);
1267 lua_setfield(L, 1, "null");
1268 // return library module (that's expected on top of stack):
1269 return 1;
1270 }