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view libraries/json/json.c @ 182:b460ae08dd78
json.import does support even more nested levels
| author | jbe |
|---|---|
| date | Sat Aug 02 02:53:32 2014 +0200 (2014-08-02) |
| parents | c2e76617c26c |
| children | f7c1869b5b32 |
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: json_import can store 2^32 / 3 levels on stack swap (using
9 // also negative indicies after integer wraparound), so
10 // 1024^3 = 1073741824 is a safe value.
11 #define JSON_MAXDEPTH (1024*1024*1024)
12 // NOTE: As long as the function json_export_internal is implemented
13 // recursively, JSON_MAXDEPTH needs to be low (e.g. 50) to avoid C stack
14 // overflows.
15 #if JSON_MAXDEPTH > 50
16 #undef JSON_MAXDEPTH
17 #define JSON_MAXDEPTH 50
18 #endif
20 // generate dummy memory addresses that represents null values:
21 char json_nullmark;
22 #define json_isnullmark(L, i) (lua_touserdata((L), (i)) == &json_nullmark)
23 #define json_pushnullmark(L) lua_pushlightuserdata((L), &json_nullmark)
25 // macros for usage of Lua registry:
26 #define JSON_REGENT char
27 #define JSON_REGPOINTER void *
28 #define json_regpointer(x) (&json_registry.x)
29 #define json_regfetchpointer(L, x) lua_rawgetp((L), LUA_REGISTRYINDEX, (x))
30 #define json_regfetch(L, x) json_regfetchpointer(L, json_regpointer(x))
31 #define json_regstore(L, x) lua_rawsetp(L, LUA_REGISTRYINDEX, json_regpointer(x))
33 // generate dummy memory addresses that represent Lua objects
34 // via lightuserdata keys and LUA_REGISTRYINDEX:
35 static struct {
36 JSON_REGENT shadowtbl; // ephemeron table that maps tables to their corresponding shadow table
37 JSON_REGENT objectmt; // metatable for JSON objects
38 JSON_REGENT arraymt; // metatable for JSON arrays
39 } json_registry;
41 // returns the string "<JSON null marker>":
42 static int json_nullmark_tostring(lua_State *L) {
43 lua_pushliteral(L, "<JSON null marker>");
44 return 1;
45 }
47 #define json_convert_source_idx 1
48 #define json_convert_iterator_idx 2
49 #define json_convert_output_idx 3
50 #define json_convert_shadow_idx 4
51 #define json_convert_iterfun_idx 5
52 #define json_convert_itertbl_idx 6
54 // converts a Lua table (or any other iterable value) to a JSON object or JSON array:
55 // (does never modify the argument, returns an empty object or array if argument is nil)
56 static int json_convert(lua_State *L, int array) {
57 int arrayidx = 0;
58 // determine is argument is given:
59 if (lua_isnoneornil(L, json_convert_source_idx)) {
60 // if no argument is given (or if argument is nil),
61 // create table with shadow table, and leave first table on top of stack:
62 json_regfetch(L, shadowtbl);
63 lua_newtable(L);
64 lua_pushvalue(L, -1);
65 lua_newtable(L);
66 lua_rawset(L, -4);
67 } else {
68 // if an argument was given,
69 // push its iterator function on stack position 2 if existent,
70 // else push null for normal tables:
71 lua_settop(L, 1);
72 if (lua_getmetatable(L, json_convert_source_idx)) {
73 lua_getfield(L, -1, array ? "__ipairs" : "__pairs");
74 if (lua_isnil(L, -1)) luaL_checktype(L, 1, LUA_TTABLE);
75 else if (lua_type(L, -1) != LUA_TFUNCTION)
76 return luaL_error(L, "%s metamethod is not a function", array ? "__ipairs" : "__pairs");
77 lua_replace(L, -2);
78 } else {
79 lua_pushnil(L);
80 }
81 // create result table on stack position 3:
82 lua_newtable(L);
83 // create shadow table on stack position 4:
84 json_regfetch(L, shadowtbl);
85 lua_newtable(L);
86 lua_pushvalue(L, json_convert_output_idx);
87 lua_pushvalue(L, -2);
88 lua_rawset(L, -4);
89 lua_replace(L, -2);
90 // check if iterator function exists:
91 if (lua_isnil(L, json_convert_iterator_idx)) {
92 // if there is no iterator function,
93 // distinguish between objects and arrays:
94 if (array == 0) {
95 // for an object, copy all string key value pairs to shadow table:
96 for (lua_pushnil(L); lua_next(L, json_convert_source_idx); lua_pop(L, 1)) {
97 if (lua_type(L, -2) == LUA_TSTRING) {
98 lua_pushvalue(L, -2);
99 lua_pushvalue(L, -2);
100 lua_rawset(L, json_convert_shadow_idx);
101 }
102 }
103 } else {
104 // for an array, copy consecutive integer value pairs to shadow table:
105 while (1) {
106 // throw error if array would exceed INT_MAX elements:
107 // TODO: Lua 5.3 may support more elements
108 if (arrayidx == INT_MAX) {
109 lua_pushnumber(L, (size_t)INT_MAX+1);
110 lua_rawget(L, json_convert_source_idx);
111 if (lua_isnil(L, -1)) break;
112 return luaL_error(L, "Array exceeded length of %d elements", INT_MAX);
113 }
114 // get next array entry:
115 arrayidx++;
116 lua_rawgeti(L, json_convert_source_idx, arrayidx);
117 // break if value is nil:
118 if (lua_isnil(L, -1)) break;
119 // store value in shadow table:
120 lua_rawseti(L, json_convert_shadow_idx, arrayidx);
121 }
122 }
123 } else {
124 // if there is an iterator function,
125 // call iterator function with source value (first argument)
126 // and store 3 result values on stack positions 5 through 7:
127 lua_pushvalue(L, json_convert_iterator_idx);
128 lua_pushvalue(L, 1);
129 lua_call(L, 1, 3);
130 // iterate through key value pairs and store some of them in shadow table
131 // while replacing nil values with null-marker:
132 while (1) {
133 // call iterfun function:
134 lua_pushvalue(L, json_convert_iterfun_idx);
135 lua_pushvalue(L, json_convert_itertbl_idx);
136 lua_pushvalue(L, -3);
137 lua_remove(L, -4);
138 lua_call(L, 2, 2);
139 // break iteration loop if key is nil:
140 if (lua_isnil(L, -2)) break;
141 // store key value pair only if key type is correct:
142 if (lua_type(L, -2) == (array ? LUA_TNUMBER : LUA_TSTRING)) {
143 // if key type is correct,
144 // push key onto stack:
145 lua_pushvalue(L, -2);
146 // if value is nil, push null-marker onto stack (as value):
147 if (lua_isnil(L, -2)) json_pushnullmark(L);
148 // else push value onto stack:
149 else lua_pushvalue(L, -2);
150 // set key value pair in shadow table:
151 lua_rawset(L, json_convert_shadow_idx);
152 }
153 // pop value from stack, but leave key on stack:
154 lua_pop(L, 1);
155 }
156 }
157 // let result table be on top of stack:
158 lua_settop(L, json_convert_output_idx);
159 }
160 // set metatable (for result table on top of stack):
161 if (array == 0) json_regfetch(L, objectmt);
162 else json_regfetch(L, arraymt);
163 lua_setmetatable(L, -2);
164 // return table on top of stack:
165 return 1;
166 }
168 // converts a Lua table (or any other iterable value) to a JSON object:
169 // (does never modify the argument, returns an empty object or array if argument is nil)
170 static int json_object(lua_State *L) {
171 return json_convert(L, 0);
172 }
174 // converts a Lua table (or any other iterable value) to a JSON array:
175 // (does never modify the argument, returns an empty object or array if argument is nil)
176 static int json_array(lua_State *L) {
177 return json_convert(L, 1);
178 }
180 // internal states of JSON parser:
181 #define JSON_STATE_VALUE 0
182 #define JSON_STATE_OBJECT_KEY 1
183 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
184 #define JSON_STATE_OBJECT_VALUE 3
185 #define JSON_STATE_OBJECT_SEPARATOR 4
186 #define JSON_STATE_ARRAY_VALUE 5
187 #define JSON_STATE_ARRAY_SEPARATOR 6
188 #define JSON_STATE_END 7
190 // special Lua stack indicies for json_import function:
191 #define json_import_objectmt_idx 2
192 #define json_import_arraymt_idx 3
193 #define json_import_shadowtbl_idx 4
194 #define json_import_stackswap_idx 5
196 // macros for hex decoding:
197 #define json_utf16_surrogate(x) ((x) >= 0xD800 && (x) <= 0xDFFF)
198 #define json_utf16_lead(x) ((x) >= 0xD800 && (x) <= 0xDBFF)
199 #define json_utf16_tail(x) ((x) >= 0xDC00 && (x) <= 0xDFFF)
200 #define json_import_readhex(x) \
201 do { \
202 x = 0; \
203 for (i=0; i<4; i++) { \
204 x <<= 4; \
205 c = str[pos++]; \
206 if (c >= '0' && c <= '9') x += c - '0'; \
207 else if (c >= 'A' && c <= 'F') x += c - 'A' + 10; \
208 else if (c >= 'a' && c <= 'f') x += c - 'a' + 10; \
209 else if (c == 0) goto json_import_unexpected_eof; \
210 else goto json_import_unexpected_escape; \
211 } \
212 } while (0)
214 // decodes a JSON document:
215 static int json_import(lua_State *L) {
216 int stackswapidx = 0; // elements in stack swap table
217 int i; // loop variable
218 const char *str; // string to parse
219 size_t total; // total length of string to parse
220 size_t pos = 0; // current position in string to parse
221 size_t level = 0; // nested levels of objects/arrays currently being processed
222 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
223 unsigned char c; // variable to store a single character to be processed (unsigned!)
224 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
225 char *cbuf; // C buffer to decode JSON string values
226 size_t outlen; // maximum length or write position of C buffer
227 long codepoint; // decoded UTF-16 character or higher codepoint
228 long utf16tail; // second decoded UTF-16 character (surrogate tail)
229 size_t arraylen; // variable to temporarily store the array length
230 // require string as argument and convert to C string with length information:
231 str = luaL_checklstring(L, 1, &total);
232 // if string contains a NULL byte, this is a syntax error
233 if (strlen(str) != total) goto json_import_syntax_error;
234 // stack shall contain one function argument:
235 lua_settop(L, 1);
236 // push objectmt onto stack position 2:
237 json_regfetch(L, objectmt);
238 // push arraymt onto stack position 3:
239 json_regfetch(L, arraymt);
240 // push shadowtbl onto stack position 4:
241 json_regfetch(L, shadowtbl);
242 // push table for stack swapping onto stack position 5:
243 // (needed to avoid Lua stack overflows)
244 lua_newtable(L);
245 // main loop of parser:
246 json_import_loop:
247 // skip whitespace and store next character in variable 'c':
248 while (c = str[pos],
249 c == ' ' ||
250 c == '\f' ||
251 c == '\n' ||
252 c == '\r' ||
253 c == '\t' ||
254 c == '\v'
255 ) pos++;
256 // NOTE: variable c needs to be unsigned in the following code
257 // switch statement to handle certain (single) characters:
258 switch (c) {
259 // handle end of JSON document:
260 case 0:
261 // if end of JSON document was expected, then return top element of stack as result:
262 if (mode == JSON_STATE_END) return 1;
263 // otherwise, the JSON document was malformed:
264 if (level == 0) {
265 lua_pushnil(L);
266 lua_pushliteral(L, "Empty string");
267 } else {
268 json_import_unexpected_eof:
269 lua_pushnil(L);
270 lua_pushliteral(L, "Unexpected end of JSON document");
271 }
272 return 2;
273 // new JSON object or JSON array:
274 case '{':
275 case '[':
276 // if an encountered JSON object is not expected here, then return an error:
277 if (
278 c == '{' &&
279 mode != JSON_STATE_VALUE &&
280 mode != JSON_STATE_OBJECT_VALUE &&
281 mode != JSON_STATE_ARRAY_VALUE
282 ) goto json_import_syntax_error;
283 // if an encountered JSON array is not expected here, then return an error:
284 if (
285 c == '[' &&
286 mode != JSON_STATE_VALUE &&
287 mode != JSON_STATE_OBJECT_VALUE &&
288 mode != JSON_STATE_ARRAY_VALUE
289 ) goto json_import_syntax_error;
290 // consume input character:
291 pos++;
292 // limit nested levels:
293 if (level >= JSON_MAXDEPTH) {
294 lua_pushnil(L);
295 lua_pushfstring(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
296 return 2;
297 }
298 // swap Lua stack entries for previous level to swap table:
299 // (avoids depth limitations due to Lua stack size)
300 if (level) {
301 lua_rawseti(L, json_import_stackswap_idx, ++stackswapidx);
302 lua_rawseti(L, json_import_stackswap_idx, ++stackswapidx);
303 lua_rawseti(L, json_import_stackswap_idx, ++stackswapidx);
304 }
305 // increment level:
306 level++;
307 // create JSON object or JSON array on stack:
308 lua_newtable(L);
309 // set metatable of JSON object or JSON array:
310 lua_pushvalue(L, c == '{' ? json_import_objectmt_idx : json_import_arraymt_idx);
311 lua_setmetatable(L, -2);
312 // create internal shadow table on stack:
313 lua_newtable(L);
314 // register internal shadow table:
315 lua_pushvalue(L, -2);
316 lua_pushvalue(L, -2);
317 lua_rawset(L, json_import_shadowtbl_idx);
318 // distinguish between JSON objects and JSON arrays:
319 if (c == '{') {
320 // if JSON object,
321 // expect object key (or end of object) to follow:
322 mode = JSON_STATE_OBJECT_KEY;
323 } else {
324 // if JSON array,
325 // expect array value (or end of array) to follow:
326 mode = JSON_STATE_ARRAY_VALUE;
327 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
328 if (c == '[') lua_pushnil(L);
329 }
330 goto json_import_loop;
331 // end of JSON object:
332 case '}':
333 // if end of JSON object is not expected here, then return an error:
334 if (
335 mode != JSON_STATE_OBJECT_KEY &&
336 mode != JSON_STATE_OBJECT_SEPARATOR
337 ) goto json_import_syntax_error;
338 // jump to common code for end of JSON object and JSON array:
339 goto json_import_close;
340 // end of JSON array:
341 case ']':
342 // if end of JSON array is not expected here, then return an error:
343 if (
344 mode != JSON_STATE_ARRAY_VALUE &&
345 mode != JSON_STATE_ARRAY_SEPARATOR
346 ) goto json_import_syntax_error;
347 // pop nil key/magic (that was needed to keep stack balance):
348 lua_pop(L, 1);
349 // continue with common code for end of JSON object and JSON array:
350 // common code for end of JSON object or JSON array:
351 json_import_close:
352 // consume input character:
353 pos++;
354 // pop shadow table:
355 lua_pop(L, 1);
356 // check if nested:
357 if (--level) {
358 // if nested,
359 // restore previous stack elements from stack swap:
360 lua_rawgeti(L, json_import_stackswap_idx, stackswapidx--);
361 lua_insert(L, -2);
362 lua_rawgeti(L, json_import_stackswap_idx, stackswapidx--);
363 lua_insert(L, -2);
364 lua_rawgeti(L, json_import_stackswap_idx, stackswapidx--);
365 lua_insert(L, -2);
366 // check if outer(!) structure is an array or object:
367 if (lua_isnil(L, -2)) {
368 // select array value processing:
369 mode = JSON_STATE_ARRAY_VALUE;
370 } else {
371 // select object value processing:
372 mode = JSON_STATE_OBJECT_VALUE;
373 }
374 // store value in outer structure:
375 goto json_import_process_value;
376 }
377 // if not nested, then expect end of JSON document and continue with loop:
378 mode = JSON_STATE_END;
379 goto json_import_loop;
380 // key terminator:
381 case ':':
382 // if key terminator is not expected here, then return an error:
383 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
384 goto json_import_syntax_error;
385 // consume input character:
386 pos++;
387 // expect object value to follow:
388 mode = JSON_STATE_OBJECT_VALUE;
389 // continue with loop:
390 goto json_import_loop;
391 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
392 case ',':
393 // branch according to parser state:
394 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
395 // expect an object key to follow:
396 mode = JSON_STATE_OBJECT_KEY;
397 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
398 // expect an array value to follow:
399 mode = JSON_STATE_ARRAY_VALUE;
400 } else {
401 // if value terminator is not expected here, then return an error:
402 goto json_import_syntax_error;
403 }
404 // consume input character:
405 pos++;
406 // continue with loop:
407 goto json_import_loop;
408 // string literal:
409 case '"':
410 // consume quote character:
411 pos++;
412 // find last character in input string:
413 outlen = pos;
414 while ((c = str[outlen]) != '"') {
415 // consume one character:
416 outlen++;
417 // handle unexpected end of JSON document:
418 if (c == 0) goto json_import_unexpected_eof;
419 // consume one extra character when encountering an escaped quote:
420 else if (c == '\\' && str[outlen] == '"') outlen++;
421 }
422 // determine buffer length:
423 outlen -= pos;
424 // check if string is non empty:
425 if (outlen) {
426 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
427 cbuf = luaL_buffinitsize(L, &luabuf, outlen);
428 outlen = 0;
429 // loop through the characters until encountering end quote:
430 while ((c = str[pos++]) != '"') {
431 // NOTE: unexpected end cannot happen anymore
432 if (c < 32 || c == 127) {
433 // do not allow ASCII control characters:
434 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
435 // by this parser to allow different encodings than Unicode
436 lua_pushnil(L);
437 lua_pushliteral(L, "Unexpected control character in JSON string");
438 return 2;
439 } else if (c == '\\') {
440 // read next char after backslash escape:
441 c = str[pos++];
442 switch (c) {
443 // unexpected end-of-string:
444 case 0:
445 goto json_import_unexpected_eof;
446 // unescaping of quotation mark, slash, and backslash:
447 case '"':
448 case '/':
449 case '\\':
450 cbuf[outlen++] = c;
451 break;
452 // unescaping of backspace:
453 case 'b': cbuf[outlen++] = '\b'; break;
454 // unescaping of form-feed:
455 case 'f': cbuf[outlen++] = '\f'; break;
456 // unescaping of new-line:
457 case 'n': cbuf[outlen++] = '\n'; break;
458 // unescaping of carriage-return:
459 case 'r': cbuf[outlen++] = '\r'; break;
460 // unescaping of tabulator:
461 case 't': cbuf[outlen++] = '\t'; break;
462 // unescaping of UTF-16 characters
463 case 'u':
464 // decode 4 hex nibbles:
465 json_import_readhex(codepoint);
466 // handle surrogate character:
467 if (json_utf16_surrogate(codepoint)) {
468 // check if first surrogate is in valid range:
469 if (json_utf16_lead(codepoint)) {
470 // require second surrogate:
471 if ((c = str[pos++]) != '\\' || (c = str[pos++]) != 'u') {
472 if (c == 0) goto json_import_unexpected_eof;
473 else goto json_import_wrong_surrogate;
474 }
475 // read 4 hex nibbles of second surrogate character:
476 json_import_readhex(utf16tail);
477 // check if second surrogate is in valid range:
478 if (!json_utf16_tail(utf16tail)) goto json_import_wrong_surrogate;
479 // calculate codepoint:
480 codepoint = 0x10000 + (utf16tail - 0xDC00) + (codepoint - 0xD800) * 0x400;
481 } else {
482 // throw error for wrong surrogates:
483 json_import_wrong_surrogate:
484 lua_pushnil(L);
485 lua_pushliteral(L, "Illegal UTF-16 surrogate in JSON string escape sequence");
486 return 2;
487 }
488 }
489 // encode as UTF-8:
490 if (codepoint < 0x80) {
491 cbuf[outlen++] = (char)codepoint;
492 } else if (codepoint < 0x800) {
493 cbuf[outlen++] = (char)(0xc0 | (codepoint >> 6));
494 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
495 } else if (codepoint < 0x10000) {
496 cbuf[outlen++] = (char)(0xe0 | (codepoint >> 12));
497 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 6) & 0x3f));
498 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
499 } else {
500 cbuf[outlen++] = (char)(0xf0 | (codepoint >> 18));
501 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 12) & 0x3f));
502 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 6) & 0x3f));
503 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
504 }
505 break;
506 // unexpected escape sequence:
507 default:
508 json_import_unexpected_escape:
509 lua_pushnil(L);
510 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
511 return 2;
512 }
513 } else {
514 // normal character:
515 cbuf[outlen++] = c;
516 }
517 }
518 // process buffer to Lua string:
519 luaL_pushresultsize(&luabuf, outlen);
520 } else {
521 // if JSON string is empty,
522 // push empty Lua string:
523 lua_pushliteral(L, "");
524 // consume closing quote:
525 pos++;
526 }
527 // continue with processing of decoded string:
528 goto json_import_process_value;
529 }
530 // process values whose type is is not deducible from a single character:
531 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
532 // for numbers,
533 // use strtod() call to parse a (double precision) floating point number:
534 double numval;
535 char *endptr;
536 numval = strtod(str+pos, &endptr);
537 // catch parsing errors:
538 if (endptr == str+pos) goto json_import_syntax_error;
539 // consume characters that were parsed:
540 pos += endptr - (str+pos);
541 // push parsed (double precision) floating point number on Lua stack:
542 lua_pushnumber(L, numval);
543 } else if (!strncmp(str+pos, "true", 4)) {
544 // consume 4 input characters for "true":
545 pos += 4;
546 // put Lua true value onto stack:
547 lua_pushboolean(L, 1);
548 } else if (!strncmp(str+pos, "false", 5)) {
549 // consume 5 input characters for "false":
550 pos += 5;
551 // put Lua false value onto stack:
552 lua_pushboolean(L, 0);
553 } else if (!strncmp(str+pos, "null", 4)) {
554 // consume 4 input characters for "null":
555 pos += 4;
556 // different behavor for top-level and sub-levels:
557 if (level) {
558 // if sub-level,
559 // push special null-marker onto stack:
560 json_pushnullmark(L);
561 } else {
562 // if top-level,
563 // push nil onto stack:
564 lua_pushnil(L);
565 }
566 } else {
567 // all other cases are a syntax error:
568 goto json_import_syntax_error;
569 }
570 // process a decoded value or key value pair (expected on top of Lua stack):
571 json_import_process_value:
572 switch (mode) {
573 // an object key has been read:
574 case JSON_STATE_OBJECT_KEY:
575 // if an object key is not a string, then this is a syntax error:
576 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
577 // expect key terminator to follow:
578 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
579 // continue with loop:
580 goto json_import_loop;
581 // a key value pair has been read:
582 case JSON_STATE_OBJECT_VALUE:
583 // store key value pair in outer shadow table:
584 lua_rawset(L, -3);
585 // expect value terminator (or end of object) to follow:
586 mode = JSON_STATE_OBJECT_SEPARATOR;
587 // continue with loop:
588 goto json_import_loop;
589 // an array value has been read:
590 case JSON_STATE_ARRAY_VALUE:
591 // get current array length:
592 arraylen = lua_rawlen(L, -3);
593 // throw error if array would exceed INT_MAX elements:
594 // TODO: Lua 5.3 may support more elements
595 if (arraylen >= INT_MAX) {
596 lua_pushnil(L);
597 lua_pushfstring(L, "Array exceeded length of %d elements", INT_MAX);
598 }
599 // store value in outer shadow table:
600 lua_rawseti(L, -3, arraylen + 1);
601 // expect value terminator (or end of object) to follow:
602 mode = JSON_STATE_ARRAY_SEPARATOR;
603 // continue with loop
604 goto json_import_loop;
605 // a single value has been read:
606 case JSON_STATE_VALUE:
607 // leave value on top of stack, expect end of JSON document, and continue with loop:
608 mode = JSON_STATE_END;
609 goto json_import_loop;
610 }
611 // syntax error handling (reachable by goto statement):
612 json_import_syntax_error:
613 lua_pushnil(L);
614 lua_pushliteral(L, "Syntax error in JSON document");
615 return 2;
616 }
618 // special Lua stack indicies for json_path function:
619 #define json_path_shadowtbl_idx 1
621 // stack offset of arguments to json_path function:
622 #define json_path_idxshift 1
624 // gets a value or its type from a JSON document (passed as first argument)
625 // using a path (passed as variable number of keys after the first argument):
626 static int json_path(lua_State *L, int type_mode) {
627 int stacktop; // stack index of top of stack (after shifting)
628 int idx = 2 + json_path_idxshift; // stack index of current argument to process
629 // require at least one argument:
630 luaL_checkany(L, 1);
631 // insert shadowtbl into stack at position 1 (shifting the arguments):
632 json_regfetch(L, shadowtbl);
633 lua_insert(L, 1);
634 // store stack index of top of stack:
635 stacktop = lua_gettop(L);
636 // use first argument as "current value" (stored on top of stack):
637 lua_pushvalue(L, 1 + json_path_idxshift);
638 // process each "path key" (2nd argument and following arguments):
639 while (idx <= stacktop) {
640 // if "current value" (on top of stack) is nil, then the path cannot be walked and nil is returned:
641 if (lua_isnil(L, -1)) return 1;
642 // try to get shadow table of "current value":
643 lua_pushvalue(L, -1);
644 lua_rawget(L, json_path_shadowtbl_idx);
645 if (lua_isnil(L, -1)) {
646 // if no shadow table is found,
647 if (lua_type(L, -1) == LUA_TTABLE) {
648 // and if "current value" is a table,
649 // drop nil from stack:
650 lua_pop(L, 1);
651 // get "next value" using the "path key":
652 lua_pushvalue(L, idx++);
653 lua_gettable(L, -2);
654 } else {
655 // if "current value" is not a table,
656 // then the path cannot be walked and nil (already on top of stack) is returned:
657 return 1;
658 }
659 } else {
660 // if a shadow table is found,
661 // set "current value" to its shadow table:
662 lua_replace(L, -2);
663 // get "next value" using the "path key":
664 lua_pushvalue(L, idx++);
665 lua_rawget(L, -2);
666 }
667 // the "next value" replaces the "current value":
668 lua_replace(L, -2);
669 }
670 if (!type_mode) {
671 // if a value (and not its type) was requested,
672 // check if value is the null-marker, and store nil on top of Lua stack in that case:
673 if (json_isnullmark(L, -1)) lua_pushnil(L);
674 } else {
675 // if the type was requested,
676 // check if value is the null-marker:
677 if (json_isnullmark(L, -1)) {
678 // if yes, store string "null" on top of Lua stack:
679 lua_pushliteral(L, "null");
680 } else {
681 // otherwise,
682 // check if metatable indicates "object" or "array":
683 if (lua_getmetatable(L, -1)) {
684 json_regfetch(L, objectmt);
685 if (lua_rawequal(L, -2, -1)) {
686 // if value has metatable for JSON objects,
687 // return string "object":
688 lua_pushliteral(L, "object");
689 return 1;
690 }
691 json_regfetch(L, arraymt);
692 if (lua_rawequal(L, -3, -1)) {
693 // if value has metatable for JSON arrays,
694 // return string "object":
695 lua_pushliteral(L, "array");
696 return 1;
697 }
698 // remove 3 metatables (one of the value, two for comparison) from stack:
699 lua_pop(L, 3);
700 }
701 // otherwise, get the Lua type:
702 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
703 }
704 }
705 // return the top most value on the Lua stack:
706 return 1;
707 }
709 // gets a value from a JSON document (passed as first argument)
710 // using a path (passed as variable number of keys after the first argument):
711 static int json_get(lua_State *L) {
712 return json_path(L, 0);
713 }
715 // gets a value's type from a JSON document (passed as first argument)
716 // using a path (passed as variable number of keys after first the argument):
717 static int json_type(lua_State *L) {
718 return json_path(L, 1);
719 }
721 // special Lua stack indicies for json_set function:
722 #define json_set_shadowtbl_idx 1
723 #define json_set_objectmt_idx 2
724 #define json_set_arraymt_idx 3
726 // stack offset of arguments to json_set function:
727 #define json_set_idxshift 3
729 // sets a value (passed as second argument) in a JSON document (passed as first argument)
730 // using a path (passed as variable number of keys starting at third argument):
731 static int json_set(lua_State *L) {
732 int stacktop; // stack index of top of stack (after shifting)
733 int idx = 3; // stack index of current argument to process
734 // require at least two arguments:
735 luaL_checkany(L, 1);
736 luaL_checkany(L, 2);
737 // insert shadowtbl into stack at position 1 (shifting the arguments):
738 json_regfetch(L, shadowtbl);
739 lua_insert(L, 1);
740 // insert objectmt into stack at position 2 (shifting the arguments):
741 json_regfetch(L, objectmt);
742 lua_insert(L, 2);
743 // insert arraymt into stack at position 3 (shifting the arguments):
744 json_regfetch(L, arraymt);
745 lua_insert(L, 3);
746 // store stack index of top of stack:
747 stacktop = lua_gettop(L);
748 // use nil as initial "parent value":
749 lua_pushnil(L);
750 // use first argument as "current value":
751 lua_pushvalue(L, 1 + json_set_idxshift);
752 // set all necessary values in path:
753 for (idx = 3 + json_set_idxshift; idx<=stacktop; idx++) {
754 // push metatable of "current value" onto stack:
755 if (!lua_getmetatable(L, -1)) lua_pushnil(L);
756 // distinguish according to type of path key:
757 switch (lua_type(L, idx)) {
758 case LUA_TSTRING:
759 // if path key is a string,
760 // check if "current value" is a JSON object (or table without metatable):
761 if (
762 lua_rawequal(L, -1, json_set_objectmt_idx) ||
763 (lua_isnil(L, -1) && lua_type(L, -2) == LUA_TTABLE)
764 ) {
765 // if "current value" is acceptable,
766 // pop metatable and leave "current value" on top of stack:
767 lua_pop(L, 1);
768 } else {
769 // if "current value" is not acceptable:
770 // pop metatable and "current value":
771 lua_pop(L, 2);
772 // throw error if parent element does not exist:
773 if (lua_isnil(L, -1)) return luaL_error(L, "Root element is not a JSON object");
774 // push new JSON object as "current value" onto stack:
775 lua_newtable(L);
776 // create and register shadow table:
777 lua_pushvalue(L, -1);
778 lua_newtable(L);
779 lua_rawset(L, json_set_shadowtbl_idx);
780 // set metatable of JSON object:
781 lua_pushvalue(L, json_set_objectmt_idx);
782 lua_setmetatable(L, -2);
783 // set entry in "parent value":
784 lua_pushvalue(L, idx-1);
785 lua_pushvalue(L, -2);
786 lua_settable(L, -4);
787 }
788 break;
789 case LUA_TNUMBER:
790 // if path key is a number,
791 // check if "current value" is a JSON array (or table without metatable):
792 if (
793 lua_rawequal(L, -1, json_set_arraymt_idx) ||
794 (lua_isnil(L, -1) && lua_type(L, -2) == LUA_TTABLE)
795 ) {
796 // if "current value" is acceptable,
797 // pop metatable and leave "current value" on top of stack:
798 lua_pop(L, 1);
799 } else {
800 // if "current value" is not acceptable:
801 // pop metatable and "current value":
802 lua_pop(L, 2);
803 // throw error if parent element does not exist:
804 if (lua_isnil(L, -1)) return luaL_error(L, "Root element is not a JSON array");
805 // push new JSON array as "current value" onto stack:
806 lua_newtable(L);
807 // create and register shadow table:
808 lua_pushvalue(L, -1);
809 lua_newtable(L);
810 lua_rawset(L, json_set_shadowtbl_idx);
811 // set metatable of JSON array:
812 lua_pushvalue(L, json_set_arraymt_idx);
813 lua_setmetatable(L, -2);
814 // set entry in "parent value":
815 lua_pushvalue(L, idx-1);
816 lua_pushvalue(L, -2);
817 lua_settable(L, -4);
818 }
819 break;
820 default:
821 return luaL_error(L, "Invalid path key of type %s", lua_typename(L, lua_type(L, idx)));
822 }
823 // check if last path element is being processed:
824 if (idx == stacktop) {
825 // if the last path element is being processed,
826 // set last path value in "current value" container:
827 lua_pushvalue(L, idx);
828 lua_pushvalue(L, 2 + json_set_idxshift);
829 lua_settable(L, -3);
830 } else {
831 // if the processed path element is not the last,
832 // use old "current value" as new "parent value"
833 lua_remove(L, -2);
834 // push new "current value" onto stack by performing a lookup:
835 lua_pushvalue(L, idx);
836 lua_gettable(L, -2);
837 }
838 }
839 // return first argument for convenience:
840 lua_settop(L, 1 + json_set_idxshift);
841 return 1;
842 }
844 // returns the length of a JSON array (or zero for a table without numeric keys):
845 static int json_len(lua_State *L) {
846 // stack shall contain one function argument:
847 lua_settop(L, 1);
848 // try to get corresponding shadow table for first argument:
849 json_regfetch(L, shadowtbl);
850 lua_pushvalue(L, 1);
851 lua_rawget(L, -2);
852 // if shadow table does not exist, return length of argument, else length of shadow table:
853 lua_pushnumber(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
854 return 1;
855 }
857 // __index metamethod for JSON objects and JSON arrays:
858 static int json_index(lua_State *L) {
859 // stack shall contain two function arguments:
860 lua_settop(L, 2);
861 // get corresponding shadow table for first argument:
862 json_regfetch(L, shadowtbl);
863 lua_pushvalue(L, 1);
864 lua_rawget(L, -2);
865 // throw error if no shadow table was found:
866 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
867 // use key passed as second argument to lookup value in shadow table:
868 lua_pushvalue(L, 2);
869 lua_rawget(L, -2);
870 // if value is null-marker, then push nil onto stack:
871 if (json_isnullmark(L, -1)) lua_pushnil(L);
872 // return either looked up value, or nil
873 return 1;
874 }
876 // __newindex metamethod for JSON objects and JSON arrays:
877 static int json_newindex(lua_State *L) {
878 // stack shall contain three function arguments:
879 lua_settop(L, 3);
880 // get corresponding shadow table for first argument:
881 json_regfetch(L, shadowtbl);
882 lua_pushvalue(L, 1);
883 lua_rawget(L, -2);
884 // throw error if no shadow table was found:
885 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
886 // replace first argument with shadow table:
887 lua_replace(L, 1);
888 // reset stack and use second and third argument to write to shadow table:
889 lua_settop(L, 3);
890 lua_rawset(L, 1);
891 // return nothing:
892 return 0;
893 }
895 // function returned as first value by json_pairs function:
896 static int json_pairs_iterfunc(lua_State *L) {
897 // stack shall contain two function arguments:
898 lua_settop(L, 2);
899 // get corresponding shadow table for first argument:
900 json_regfetch(L, shadowtbl);
901 lua_pushvalue(L, 1);
902 lua_rawget(L, -2);
903 // throw error if no shadow table was found:
904 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
905 // get next key value pair from shadow table (using previous key from argument 2)
906 // and return nothing if there is no next pair:
907 lua_pushvalue(L, 2);
908 if (!lua_next(L, -2)) return 0;
909 // replace null-marker with nil:
910 if (json_isnullmark(L, -1)) {
911 lua_pop(L, 1);
912 lua_pushnil(L);
913 }
914 // return key and value (or key and nil, if null-marker was found):
915 return 2;
916 }
918 // returns a triple such that 'for key, value in pairs(obj) do ... end'
919 // iterates through all key value pairs (including JSON null values represented as Lua nil):
920 static int json_pairs(lua_State *L) {
921 // require one argument to function
922 luaL_checkany(L, 1);
923 // return triple of function json_pairs_iterfunc, first argument, and nil:
924 lua_pushcfunction(L, json_pairs_iterfunc);
925 lua_pushvalue(L, 1);
926 lua_pushnil(L);
927 return 3;
928 }
930 // function returned as first value by json_ipairs function:
931 static int json_ipairs_iterfunc(lua_State *L) {
932 lua_Integer idx;
933 // stack shall contain two function arguments:
934 lua_settop(L, 2);
935 // calculate new index by incrementing second argument:
936 idx = lua_tointeger(L, 2) + 1;
937 // get corresponding shadow table for first argument:
938 json_regfetch(L, shadowtbl);
939 lua_pushvalue(L, 1);
940 lua_rawget(L, -2);
941 // throw error if no shadow table was found:
942 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
943 // do integer lookup in shadow table:
944 lua_rawgeti(L, -1, idx);
945 // return nothing if there was no value:
946 if (lua_isnil(L, -1)) return 0;
947 // return new index and
948 // either the looked up value if it is not equal to the null-marker
949 // or nil instead of null-marker:
950 lua_pushinteger(L, idx);
951 if (json_isnullmark(L, -2)) lua_pushnil(L);
952 else lua_pushvalue(L, -2);
953 return 2;
954 }
956 // returns a triple such that 'for idx, value in ipairs(ary) do ... end'
957 // iterates through all values (including JSON null values represented as Lua nil):
958 static int json_ipairs(lua_State *L) {
959 // require one argument to function
960 luaL_checkany(L, 1);
961 // return triple of function json_ipairs_iterfunc, first argument, and zero:
962 lua_pushcfunction(L, json_ipairs_iterfunc);
963 lua_pushvalue(L, 1);
964 lua_pushinteger(L, 0);
965 return 3;
966 }
968 // datatype representing a table key:
969 // (used for sorting)
970 typedef struct {
971 size_t length;
972 const char *data;
973 } json_key_t;
975 // comparation function for table keys to be passed to qsort function:
976 static int json_key_cmp(json_key_t *key1, json_key_t *key2) {
977 size_t pos = 0;
978 unsigned char c1, c2;
979 while (1) {
980 if (key1->length > pos) {
981 if (key2->length > pos) {
982 c1 = key1->data[pos];
983 c2 = key2->data[pos];
984 if (c1 < c2) return -1;
985 else if (c1 > c2) return 1;
986 } else {
987 return 1;
988 }
989 } else {
990 if (key2->length > pos) {
991 return -1;
992 } else {
993 return 0;
994 }
995 }
996 pos++;
997 }
998 }
1000 // constants for type detection of ambiguous tables:
1001 #define JSON_TABLETYPE_UNKNOWN 0
1002 #define JSON_TABLETYPE_OBJECT 1
1003 #define JSON_TABLETYPE_ARRAY 2
1005 // special Lua stack indicies for json_export_internal function:
1006 #define json_export_internal_indentstring_idx 1
1007 #define json_export_internal_level_idx 2
1008 #define json_export_internal_value_idx 3
1009 #define json_export_internal_tmp_idx 4
1011 // encodes a JSON document (passed as third argument)
1012 // optionally using indentation (indentation string passed as first argument)
1013 // for a certain depth level (passed as second argument):
1014 static int json_export_internal(lua_State *L) {
1015 int level; // current depth level
1016 int pretty; // pretty printing on? (i.e. printing with indentation)
1017 int i; // iteration variable for level dependent repetitions:
1018 lua_Number num; // number to encode
1019 const char *str; // string to encode
1020 size_t strlen; // length of string to encode
1021 unsigned char c; // character to encode (unsigned!)
1022 size_t pos = 0; // position in string or position of current key (initialized with zero!)
1023 luaL_Buffer buf; // Lua buffer to create strings
1024 char hexcode[7]; // store for unicode hex escape sequence
1025 // NOTE: 7 bytes due to backslash, character 'u', 4 hex digits, and terminating NULL byte
1026 int tabletype = JSON_TABLETYPE_UNKNOWN; // table type: unknown, JSON object, or JSON array
1027 int anyelement = 0; // set to 1 if at least one array element has been processed
1028 size_t keycount = 0; // number of string keys in object
1029 json_key_t *keybuf = NULL; // temporary buffer to store (and sort) string keys of objects
1030 lua_Integer arrayidx; // index to iterate through arrays
1031 // stack shall contain three function arguments:
1032 lua_settop(L, json_export_internal_value_idx);
1033 // if value to encode is the null-marker, then treat it the same as nil:
1034 if (json_isnullmark(L, json_export_internal_value_idx)) {
1035 lua_pop(L, 1);
1036 lua_pushnil(L);
1037 }
1038 // distinguish between different Lua types:
1039 switch (lua_type(L, json_export_internal_value_idx)) {
1040 // value to encode is nil:
1041 case LUA_TNIL:
1042 // return string "null":
1043 lua_pushliteral(L, "null");
1044 return 1;
1045 // value to encode is of type number:
1046 case LUA_TNUMBER:
1047 // convert value to double precision number:
1048 num = lua_tonumber(L, json_export_internal_value_idx);
1049 // throw error if number is not-a-number:
1050 if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
1051 // throw error if number is positive or negative infinity:
1052 if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
1053 // return Lua's string encoding of the number:
1054 lua_tostring(L, json_export_internal_value_idx);
1055 return 1;
1056 // value to encode is of type boolean:
1057 case LUA_TBOOLEAN:
1058 // return string "true" or "false" according to boolean value:
1059 if (lua_toboolean(L, json_export_internal_value_idx)) {
1060 lua_pushliteral(L, "true");
1061 } else {
1062 lua_pushliteral(L, "false");
1063 }
1064 return 1;
1065 // value to encode is of type string:
1066 case LUA_TSTRING:
1067 // quote, escape and return string:
1068 str = lua_tolstring(L, 3, &strlen);
1069 luaL_buffinit(L, &buf);
1070 luaL_addchar(&buf, '"');
1071 while (pos < strlen) {
1072 c = str[pos++];
1073 if (c == '"') luaL_addstring(&buf, "\\\"");
1074 else if (c == '\\') luaL_addstring(&buf, "\\\\");
1075 else if (c == 127) luaL_addstring(&buf, "\\u007F");
1076 else if (c >= 32) luaL_addchar(&buf, c);
1077 else if (c == '\b') luaL_addstring(&buf, "\\b");
1078 else if (c == '\f') luaL_addstring(&buf, "\\f");
1079 else if (c == '\n') luaL_addstring(&buf, "\\n");
1080 else if (c == '\r') luaL_addstring(&buf, "\\r");
1081 else if (c == '\t') luaL_addstring(&buf, "\\t");
1082 else if (c == '\v') luaL_addstring(&buf, "\\v");
1083 else {
1084 sprintf(hexcode, "\\u%04X", c);
1085 luaL_addstring(&buf, hexcode);
1086 }
1087 }
1088 luaL_addchar(&buf, '"');
1089 luaL_pushresult(&buf);
1090 return 1;
1091 // value to encode is of type table (this includes JSON objects and JSON arrays):
1092 case LUA_TTABLE:
1093 // use table's metatable to try to determine type of table:
1094 if (lua_getmetatable(L, json_export_internal_value_idx)) {
1095 json_regfetch(L, objectmt);
1096 if (lua_rawequal(L, -2, -1)) {
1097 tabletype = JSON_TABLETYPE_OBJECT;
1098 } else {
1099 json_regfetch(L, arraymt);
1100 if (lua_rawequal(L, -3, -1)) {
1101 tabletype = JSON_TABLETYPE_ARRAY;
1102 } else {
1103 return luaL_error(L, "JSON export not possible for tables with nonsupported metatable");
1104 }
1105 }
1106 }
1107 // replace table with its shadow table if existent, and reset stack:
1108 json_regfetch(L, shadowtbl);
1109 lua_pushvalue(L, json_export_internal_value_idx);
1110 lua_rawget(L, -2);
1111 if (!lua_isnil(L, -1)) lua_replace(L, json_export_internal_value_idx);
1112 lua_settop(L, json_export_internal_value_idx);
1113 // check if type of table is still undetermined:
1114 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
1115 // if yes, iterate over all keys:
1116 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1117 switch (lua_type(L, -2)) {
1118 case LUA_TSTRING:
1119 // for string keys,
1120 // increase keycount (may avoid another iteration):
1121 keycount++;
1122 // if type of table was unknown, then type of table is a JSON object now:
1123 if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_OBJECT;
1124 // if type of table was a JSON array, then the type of table is ambiguous now
1125 // and an error is thrown:
1126 else if (tabletype == JSON_TABLETYPE_ARRAY) goto json_export_tabletype_error;
1127 break;
1128 case LUA_TNUMBER:
1129 // for numeric keys,
1130 // if type of table was unknown, then type of table is a JSON array now:
1131 if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_ARRAY;
1132 // if type of table was a JSON object, then the type of table is ambiguous now
1133 // and an error is thrown:
1134 else if (tabletype == JSON_TABLETYPE_OBJECT) goto json_export_tabletype_error;
1135 break;
1136 }
1137 }
1138 }
1139 // set pretty variable to 1 if pretty printing (with indentation) is desired:
1140 pretty = lua_toboolean(L, json_export_internal_indentstring_idx);
1141 // set level variable to corresponding function argument increased by one:
1142 level = lua_tointeger(L, json_export_internal_level_idx) + 1;
1143 // throw error if there are more levels that could be imported by this library:
1144 if (level > JSON_MAXDEPTH) {
1145 return luaL_error(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
1146 }
1147 // distinguish between JSON objects and JSON arrays:
1148 switch (tabletype) {
1149 // JSON object:
1150 case JSON_TABLETYPE_OBJECT:
1151 // calculate count of string keys unless it has been calculated before:
1152 if (!keycount) {
1153 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1154 if (lua_type(L, -2) == LUA_TSTRING) keycount++;
1155 }
1156 }
1157 // create a sorted list of all string keys in memory:
1158 if (keycount) {
1159 // allocate memory for string keys:
1160 keybuf = calloc(keycount, sizeof(json_key_t));
1161 // check if memory allocation was successful:
1162 if (!keybuf) {
1163 // in case of memory exhaustion, try to collect garbage:
1164 lua_gc(L, LUA_GCCOLLECT, 0);
1165 // try to allocate memory again:
1166 keybuf = calloc(keycount, sizeof(json_key_t));
1167 // throw error if memory allocation failed again:
1168 if (!keybuf) {
1169 return luaL_error(L, "Memory allocation failed in JSON library");
1170 }
1171 }
1172 // copy all string keys to the C array:
1173 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1174 if (lua_type(L, -2) == LUA_TSTRING) {
1175 json_key_t *key = keybuf + (pos++);
1176 key->data = lua_tolstring(L, -2, &key->length);
1177 }
1178 }
1179 // sort C array using quicksort:
1180 qsort(keybuf, keycount, sizeof(json_key_t), (void *)json_key_cmp);
1181 }
1182 // create Lua string buffer:
1183 luaL_buffinit(L, &buf);
1184 // add opening bracket to output buffer:
1185 luaL_addchar(&buf, '{');
1186 // iterate through all (sorted) string keys:
1187 for (pos=0; pos<keycount; pos++) {
1188 json_key_t *key = keybuf + pos;
1189 // add comma to output buffer unless we process the first key:
1190 if (pos) luaL_addchar(&buf, ',');
1191 // handle indentation for pretty results:
1192 if (pretty) {
1193 luaL_addchar(&buf, '\n');
1194 for (i=0; i<level; i++) {
1195 lua_pushvalue(L, json_export_internal_indentstring_idx);
1196 luaL_addvalue(&buf);
1197 }
1198 }
1199 // recursive call to encode key:
1200 lua_pushcfunction(L, json_export_internal);
1201 lua_pushvalue(L, json_export_internal_indentstring_idx);
1202 lua_pushinteger(L, level);
1203 lua_pushlstring(L, key->data, key->length);
1204 if (lua_pcall(L, 3, 1, 0)) {
1205 // free memory of sorted string keys on error:
1206 if (keybuf) free(keybuf);
1207 // rethrow error:
1208 return lua_error(L);
1209 }
1210 // add encoded key to output buffer:
1211 luaL_addvalue(&buf);
1212 // add colon to output buffer:
1213 luaL_addchar(&buf, ':');
1214 // handle indentation for pretty results:
1215 if (pretty) luaL_addchar(&buf, ' ');
1216 // recursive call to encode value:
1217 lua_pushcfunction(L, json_export_internal);
1218 lua_pushvalue(L, json_export_internal_indentstring_idx);
1219 lua_pushinteger(L, level);
1220 lua_pushlstring(L, key->data, key->length);
1221 lua_rawget(L, json_export_internal_value_idx);
1222 if (lua_pcall(L, 3, 1, 0)) {
1223 // free memory of sorted string keys on error:
1224 if (keybuf) free(keybuf);
1225 // rethrow error:
1226 return lua_error(L);
1227 }
1228 // add encoded value to output buffer:
1229 luaL_addvalue(&buf);
1230 }
1231 // decrement level variable for all following statements:
1232 level--;
1233 // free memory of sorted string keys:
1234 if (keybuf) free(keybuf);
1235 // handle indentation for pretty results:
1236 if (pretty && keycount != 0) {
1237 luaL_addchar(&buf, '\n');
1238 for (i=0; i<level; i++) {
1239 lua_pushvalue(L, json_export_internal_indentstring_idx);
1240 luaL_addvalue(&buf);
1241 }
1242 }
1243 // add closing bracket to output buffer:
1244 luaL_addchar(&buf, '}');
1245 // for pretty results, add final newline character if outermost container is processed:
1246 if (pretty && level == 0) luaL_addchar(&buf, '\n');
1247 // convert and return buffer:
1248 luaL_pushresult(&buf);
1249 return 1;
1250 // JSON array:
1251 case JSON_TABLETYPE_ARRAY:
1252 // reserve an extra element on the stack (needed because Lua buffer has unknown size on stack):
1253 lua_settop(L, json_export_internal_tmp_idx);
1254 // create Lua string buffer:
1255 luaL_buffinit(L, &buf);
1256 // add opening bracket to output buffer:
1257 luaL_addchar(&buf, '[');
1258 // iterate through integer keys:
1259 for (arrayidx = 1; ; arrayidx++) {
1260 // get value in array, and break if nil:
1261 lua_rawgeti(L, json_export_internal_value_idx, arrayidx);
1262 if (lua_isnil(L, -1)) {
1263 lua_pop(L, 1);
1264 break;
1265 }
1266 // store value below Lua string buffer on stack (to allow operation on string buffer):
1267 lua_replace(L, json_export_internal_tmp_idx);
1268 //
1269 // add comma to output buffer unless we process the first element:
1270 if (anyelement) luaL_addchar(&buf, ',');
1271 // remember that we processed an element:
1272 anyelement = 1;
1273 // handle indentation for pretty results:
1274 if (pretty) {
1275 luaL_addchar(&buf, '\n');
1276 for (i=0; i<level; i++) {
1277 lua_pushvalue(L, json_export_internal_indentstring_idx);
1278 luaL_addvalue(&buf);
1279 }
1280 }
1281 // recursive call to encode previously stored value:
1282 lua_pushcfunction(L, json_export_internal);
1283 lua_pushvalue(L, json_export_internal_indentstring_idx);
1284 lua_pushinteger(L, level);
1285 lua_pushvalue(L, json_export_internal_tmp_idx);
1286 lua_call(L, 3, 1);
1287 // add encoded value to output buffer:
1288 luaL_addvalue(&buf);
1289 }
1290 // decrement level variable for all following statements:
1291 level--;
1292 // handle indentation for pretty results:
1293 if (pretty && anyelement) {
1294 luaL_addchar(&buf, '\n');
1295 for (i=0; i<level; i++) {
1296 lua_pushvalue(L, json_export_internal_indentstring_idx);
1297 luaL_addvalue(&buf);
1298 }
1299 }
1300 // add closing bracket to output buffer:
1301 luaL_addchar(&buf, ']');
1302 // for pretty results, add final newline character if outermost container is processed:
1303 if (pretty && level == 0) luaL_addchar(&buf, '\n');
1304 // convert and return buffer:
1305 luaL_pushresult(&buf);
1306 return 1;
1307 }
1308 // throw error if table type is unknown:
1309 json_export_tabletype_error:
1310 return luaL_error(L, "JSON export not possible for ambiguous table (cannot decide whether it is an object or array)");
1311 }
1312 // all other datatypes are considered an error:
1313 return luaL_error(L, "JSON export not possible for values of type \"%s\"", lua_typename(L, lua_type(L, json_export_internal_value_idx)));
1314 }
1316 // encodes a JSON document (passed as argument):
1317 static int json_export(lua_State *L) {
1318 // stack shall contain one function argument:
1319 lua_settop(L, 1);
1320 // call json_export_internal function with proper arguments:
1321 lua_pushcfunction(L, json_export_internal);
1322 lua_pushnil(L);
1323 lua_pushinteger(L, 0);
1324 lua_pushvalue(L, 1);
1325 lua_call(L, 3, 1);
1326 // return result:
1327 return 1;
1328 }
1330 // encodes a JSON document (passed as first argument)
1331 // with indentation (indentation string may be passed as second argument):
1332 static int json_pretty(lua_State *L) {
1333 // stack shall contain two function arguments:
1334 lua_settop(L, 2);
1335 // call json_export_internal function with proper arguments:
1336 lua_pushcfunction(L, json_export_internal);
1337 if (lua_isnil(L, 2)) lua_pushliteral(L, " ");
1338 else lua_pushvalue(L, 2);
1339 lua_pushinteger(L, 0);
1340 lua_pushvalue(L, 1);
1341 lua_call(L, 3, 1);
1342 // return result:
1343 return 1;
1344 }
1346 // functions in library module:
1347 static const struct luaL_Reg json_module_functions[] = {
1348 {"object", json_object},
1349 {"array", json_array},
1350 {"import", json_import},
1351 {"export", json_export},
1352 {"pretty", json_pretty},
1353 {"get", json_get},
1354 {"type", json_type},
1355 {"set", json_set},
1356 {NULL, NULL}
1357 };
1359 // metamethods for JSON objects, JSON arrays, and unknown JSON collections (object or array):
1360 static const struct luaL_Reg json_metatable_functions[] = {
1361 {"__len", json_len},
1362 {"__index", json_index},
1363 {"__newindex", json_newindex},
1364 {"__pairs", json_pairs},
1365 {"__ipairs", json_ipairs},
1366 {"__tostring", json_export},
1367 {NULL, NULL}
1368 };
1370 // metamethods for JSON null marker:
1371 static const struct luaL_Reg json_nullmark_metamethods[] = {
1372 {"__tostring", json_nullmark_tostring},
1373 {NULL, NULL}
1374 };
1376 // initializes json library:
1377 int luaopen_json(lua_State *L) {
1378 // empty stack:
1379 lua_settop(L, 0);
1380 // push library module onto stack position 1:
1381 lua_newtable(L);
1382 // register library functions:
1383 luaL_setfuncs(L, json_module_functions, 0);
1384 // create and store objectmt:
1385 lua_newtable(L);
1386 luaL_setfuncs(L, json_metatable_functions, 0);
1387 json_regstore(L, objectmt);
1388 // create and store arraymt:
1389 lua_newtable(L);
1390 luaL_setfuncs(L, json_metatable_functions, 0);
1391 json_regstore(L, arraymt);
1392 // create and store ephemeron table to store shadow tables for each JSON object/array
1393 // to allow NULL values returned as nil
1394 lua_newtable(L);
1395 lua_newtable(L); // metatable for ephemeron table
1396 lua_pushliteral(L, "__mode");
1397 lua_pushliteral(L, "k");
1398 lua_rawset(L, -3);
1399 lua_setmetatable(L, -2);
1400 json_regstore(L, shadowtbl);
1401 // set metatable of null marker and make it available through library module:
1402 json_pushnullmark(L);
1403 lua_newtable(L);
1404 luaL_setfuncs(L, json_nullmark_metamethods, 0);
1405 lua_setmetatable(L, -2);
1406 lua_setfield(L, 1, "null");
1407 // return library module (that's expected on top of stack):
1408 return 1;
1409 }