webmcp
view libraries/json/json.c @ 180:887b77f71e5e
Added #undef to json.c to avoid compiler warning
| author | jbe |
|---|---|
| date | Sat Aug 02 00:39:41 2014 +0200 (2014-08-02) |
| parents | 461e5353ffb1 |
| children | c2e76617c26c |
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
16 // NOTE: As long as the function json_export_internal is implemented
17 // recursively, JSON_MAXDEPTH needs to be low (e.g. 50) to avoid C stack
18 // overflows.
19 #if JSON_MAXDEPTH > 50
20 #undef JSON_MAXDEPTH
21 #define JSON_MAXDEPTH 50
22 #endif
24 // generate dummy memory addresses that represents null values:
25 char json_nullmark;
26 #define json_isnullmark(L, i) (lua_touserdata((L), (i)) == &json_nullmark)
27 #define json_pushnullmark(L) lua_pushlightuserdata((L), &json_nullmark)
29 // macros for usage of Lua registry:
30 #define JSON_REGENT char
31 #define JSON_REGPOINTER void *
32 #define json_regpointer(x) (&json_registry.x)
33 #define json_regfetchpointer(L, x) lua_rawgetp((L), LUA_REGISTRYINDEX, (x))
34 #define json_regfetch(L, x) json_regfetchpointer(L, json_regpointer(x))
35 #define json_regstore(L, x) lua_rawsetp(L, LUA_REGISTRYINDEX, json_regpointer(x))
37 // generate dummy memory addresses that represent Lua objects
38 // via lightuserdata keys and LUA_REGISTRYINDEX:
39 static struct {
40 JSON_REGENT shadowtbl; // ephemeron table that maps tables to their corresponding shadow table
41 JSON_REGENT objectmt; // metatable for JSON objects
42 JSON_REGENT arraymt; // metatable for JSON arrays
43 } json_registry;
45 // returns the string "<JSON null marker>":
46 static int json_nullmark_tostring(lua_State *L) {
47 lua_pushliteral(L, "<JSON null marker>");
48 return 1;
49 }
51 #define json_convert_source_idx 1
52 #define json_convert_iterator_idx 2
53 #define json_convert_output_idx 3
54 #define json_convert_shadow_idx 4
55 #define json_convert_iterfun_idx 5
56 #define json_convert_itertbl_idx 6
58 // converts a Lua table (or any other iterable value) to a JSON object or JSON array:
59 // (does never modify the argument, returns an empty object or array if argument is nil)
60 static int json_convert(lua_State *L, int array) {
61 int arrayidx = 0;
62 // determine is argument is given:
63 if (lua_isnoneornil(L, json_convert_source_idx)) {
64 // if no argument is given (or if argument is nil),
65 // create table with shadow table, and leave first table on top of stack:
66 json_regfetch(L, shadowtbl);
67 lua_newtable(L);
68 lua_pushvalue(L, -1);
69 lua_newtable(L);
70 lua_rawset(L, -4);
71 } else {
72 // if an argument was given,
73 // push its iterator function on stack position 2 if existent,
74 // else push null for normal tables:
75 lua_settop(L, 1);
76 if (lua_getmetatable(L, json_convert_source_idx)) {
77 lua_getfield(L, -1, array ? "__ipairs" : "__pairs");
78 if (lua_isnil(L, -1)) luaL_checktype(L, 1, LUA_TTABLE);
79 else if (lua_type(L, -1) != LUA_TFUNCTION)
80 return luaL_error(L, "%s metamethod is not a function", array ? "__ipairs" : "__pairs");
81 lua_replace(L, -2);
82 } else {
83 lua_pushnil(L);
84 }
85 // create result table on stack position 3:
86 lua_newtable(L);
87 // create shadow table on stack position 4:
88 json_regfetch(L, shadowtbl);
89 lua_newtable(L);
90 lua_pushvalue(L, json_convert_output_idx);
91 lua_pushvalue(L, -2);
92 lua_rawset(L, -4);
93 lua_replace(L, -2);
94 // check if iterator function exists:
95 if (lua_isnil(L, json_convert_iterator_idx)) {
96 // if there is no iterator function,
97 // distinguish between objects and arrays:
98 if (array == 0) {
99 // for an object, copy all string key value pairs to shadow table:
100 for (lua_pushnil(L); lua_next(L, json_convert_source_idx); lua_pop(L, 1)) {
101 if (lua_type(L, -2) == LUA_TSTRING) {
102 lua_pushvalue(L, -2);
103 lua_pushvalue(L, -2);
104 lua_rawset(L, json_convert_shadow_idx);
105 }
106 }
107 } else {
108 // for an array, copy consecutive integer value pairs to shadow table:
109 while (1) {
110 // throw error if array would exceed INT_MAX elements:
111 // TODO: Lua 5.3 may support more elements
112 if (arrayidx == INT_MAX) {
113 lua_pushnumber(L, (size_t)INT_MAX+1);
114 lua_rawget(L, json_convert_source_idx);
115 if (lua_isnil(L, -1)) break;
116 return luaL_error(L, "Array exceeded length of %d elements", INT_MAX);
117 }
118 // get next array entry:
119 arrayidx++;
120 lua_rawgeti(L, json_convert_source_idx, arrayidx);
121 // break if value is nil:
122 if (lua_isnil(L, -1)) break;
123 // store value in shadow table:
124 lua_rawseti(L, json_convert_shadow_idx, arrayidx);
125 }
126 }
127 } else {
128 // if there is an iterator function,
129 // call iterator function with source value (first argument)
130 // and store 3 result values on stack positions 5 through 7:
131 lua_pushvalue(L, json_convert_iterator_idx);
132 lua_pushvalue(L, 1);
133 lua_call(L, 1, 3);
134 // iterate through key value pairs and store some of them in shadow table
135 // while replacing nil values with null-marker:
136 while (1) {
137 // call iterfun function:
138 lua_pushvalue(L, json_convert_iterfun_idx);
139 lua_pushvalue(L, json_convert_itertbl_idx);
140 lua_pushvalue(L, -3);
141 lua_remove(L, -4);
142 lua_call(L, 2, 2);
143 // break iteration loop if key is nil:
144 if (lua_isnil(L, -2)) break;
145 // store key value pair only if key type is correct:
146 if (lua_type(L, -2) == (array ? LUA_TNUMBER : LUA_TSTRING)) {
147 // if key type is correct,
148 // push key onto stack:
149 lua_pushvalue(L, -2);
150 // if value is nil, push null-marker onto stack (as value):
151 if (lua_isnil(L, -2)) json_pushnullmark(L);
152 // else push value onto stack:
153 else lua_pushvalue(L, -2);
154 // set key value pair in shadow table:
155 lua_rawset(L, json_convert_shadow_idx);
156 }
157 // pop value from stack, but leave key on stack:
158 lua_pop(L, 1);
159 }
160 }
161 // let result table be on top of stack:
162 lua_settop(L, json_convert_output_idx);
163 }
164 // set metatable (for result table on top of stack):
165 if (array == 0) json_regfetch(L, objectmt);
166 else json_regfetch(L, arraymt);
167 lua_setmetatable(L, -2);
168 // return table on top of stack:
169 return 1;
170 }
172 // converts a Lua table (or any other iterable value) to a JSON object:
173 // (does never modify the argument, returns an empty object or array if argument is nil)
174 static int json_object(lua_State *L) {
175 return json_convert(L, 0);
176 }
178 // converts a Lua table (or any other iterable value) to a JSON array:
179 // (does never modify the argument, returns an empty object or array if argument is nil)
180 static int json_array(lua_State *L) {
181 return json_convert(L, 1);
182 }
184 // internal states of JSON parser:
185 #define JSON_STATE_VALUE 0
186 #define JSON_STATE_OBJECT_KEY 1
187 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
188 #define JSON_STATE_OBJECT_VALUE 3
189 #define JSON_STATE_OBJECT_SEPARATOR 4
190 #define JSON_STATE_ARRAY_VALUE 5
191 #define JSON_STATE_ARRAY_SEPARATOR 6
192 #define JSON_STATE_END 7
194 // special Lua stack indicies for json_import function:
195 #define json_import_objectmt_idx 2
196 #define json_import_arraymt_idx 3
197 #define json_import_shadowtbl_idx 4
199 // macros for hex decoding:
200 #define json_utf16_surrogate(x) ((x) >= 0xD800 && (x) <= 0xDFFF)
201 #define json_utf16_lead(x) ((x) >= 0xD800 && (x) <= 0xDBFF)
202 #define json_utf16_tail(x) ((x) >= 0xDC00 && (x) <= 0xDFFF)
203 #define json_import_readhex(x) \
204 do { \
205 x = 0; \
206 for (i=0; i<4; i++) { \
207 x <<= 4; \
208 c = str[pos++]; \
209 if (c >= '0' && c <= '9') x += c - '0'; \
210 else if (c >= 'A' && c <= 'F') x += c - 'A' + 10; \
211 else if (c >= 'a' && c <= 'f') x += c - 'a' + 10; \
212 else if (c == 0) goto json_import_unexpected_eof; \
213 else goto json_import_unexpected_escape; \
214 } \
215 } while (0)
217 // decodes a JSON document:
218 static int json_import(lua_State *L) {
219 int i; // loop variable
220 const char *str; // string to parse
221 size_t total; // total length of string to parse
222 size_t pos = 0; // current position in string to parse
223 size_t level = 0; // nested levels of objects/arrays currently being processed
224 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
225 unsigned char c; // variable to store a single character to be processed (unsigned!)
226 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
227 char *cbuf; // C buffer to decode JSON string values
228 size_t outlen; // maximum length or write position of C buffer
229 long codepoint; // decoded UTF-16 character or higher codepoint
230 long utf16tail; // second decoded UTF-16 character (surrogate tail)
231 size_t arraylen; // variable to temporarily store the array length
232 // require string as argument and convert to C string with length information:
233 str = luaL_checklstring(L, 1, &total);
234 // if string contains a NULL byte, this is a syntax error
235 if (strlen(str) != total) goto json_import_syntax_error;
236 // stack shall contain one function argument:
237 lua_settop(L, 1);
238 // push objectmt onto stack position 2:
239 json_regfetch(L, objectmt);
240 // push arraymt onto stack position 3:
241 json_regfetch(L, arraymt);
242 // push shadowtbl onto stack position 4:
243 json_regfetch(L, shadowtbl);
244 // main loop of parser:
245 json_import_loop:
246 // skip whitespace and store next character in variable 'c':
247 while (c = str[pos],
248 c == ' ' ||
249 c == '\f' ||
250 c == '\n' ||
251 c == '\r' ||
252 c == '\t' ||
253 c == '\v'
254 ) pos++;
255 // NOTE: variable c needs to be unsigned in the following code
256 // switch statement to handle certain (single) characters:
257 switch (c) {
258 // handle end of JSON document:
259 case 0:
260 // if end of JSON document was expected, then return top element of stack as result:
261 if (mode == JSON_STATE_END) return 1;
262 // otherwise, the JSON document was malformed:
263 if (level == 0) {
264 lua_pushnil(L);
265 lua_pushliteral(L, "Empty string");
266 } else {
267 json_import_unexpected_eof:
268 lua_pushnil(L);
269 lua_pushliteral(L, "Unexpected end of JSON document");
270 }
271 return 2;
272 // new JSON object:
273 case '{':
274 // if a JSON object is not expected here, then return an error:
275 if (
276 mode != JSON_STATE_VALUE &&
277 mode != JSON_STATE_OBJECT_VALUE &&
278 mode != JSON_STATE_ARRAY_VALUE
279 ) goto json_import_syntax_error;
280 // create JSON object on stack:
281 lua_newtable(L);
282 // set metatable of JSON object:
283 lua_pushvalue(L, json_import_objectmt_idx);
284 lua_setmetatable(L, -2);
285 // create internal shadow table on stack:
286 lua_newtable(L);
287 // register internal shadow table:
288 lua_pushvalue(L, -2);
289 lua_pushvalue(L, -2);
290 lua_rawset(L, json_import_shadowtbl_idx);
291 // expect object key (or end of object) to follow:
292 mode = JSON_STATE_OBJECT_KEY;
293 // jump to common code for opening JSON object and JSON array:
294 goto json_import_open;
295 // new JSON array:
296 case '[':
297 // if a JSON array is not expected here, then return an error:
298 if (
299 mode != JSON_STATE_VALUE &&
300 mode != JSON_STATE_OBJECT_VALUE &&
301 mode != JSON_STATE_ARRAY_VALUE
302 ) goto json_import_syntax_error;
303 // create JSON array on stack:
304 lua_newtable(L);
305 // set metatable of JSON array:
306 lua_pushvalue(L, json_import_arraymt_idx);
307 lua_setmetatable(L, -2);
308 // create internal shadow table on stack:
309 lua_newtable(L);
310 // register internal shadow table:
311 lua_pushvalue(L, -2);
312 lua_pushvalue(L, -2);
313 lua_rawset(L, json_import_shadowtbl_idx);
314 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
315 lua_pushnil(L);
316 // expect array value (or end of array) to follow:
317 mode = JSON_STATE_ARRAY_VALUE;
318 // continue with common code for opening JSON object and JSON array:
319 // common code for opening JSON object or JSON array:
320 json_import_open:
321 // limit nested levels:
322 if (level >= JSON_MAXDEPTH) {
323 lua_pushnil(L);
324 lua_pushfstring(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
325 return 2;
326 }
327 // additional buffer overflow protection:
328 if (!lua_checkstack(L, LUA_MINSTACK))
329 return luaL_error(L, "Caught stack overflow in JSON import function (too many nested levels and stack size too small)");
330 // increment level:
331 level++;
332 // consume input character:
333 pos++;
334 goto json_import_loop;
335 // end of JSON object:
336 case '}':
337 // if end of JSON object is not expected here, then return an error:
338 if (
339 mode != JSON_STATE_OBJECT_KEY &&
340 mode != JSON_STATE_OBJECT_SEPARATOR
341 ) goto json_import_syntax_error;
342 // jump to common code for end of JSON object and JSON array:
343 goto json_import_close;
344 // end of JSON array:
345 case ']':
346 // if end of JSON array is not expected here, then return an error:
347 if (
348 mode != JSON_STATE_ARRAY_VALUE &&
349 mode != JSON_STATE_ARRAY_SEPARATOR
350 ) goto json_import_syntax_error;
351 // pop nil key/magic (that was needed to keep stack balance):
352 lua_pop(L, 1);
353 // continue with common code for end of JSON object and JSON array:
354 // common code for end of JSON object or JSON array:
355 json_import_close:
356 // consume input character:
357 pos++;
358 // pop shadow table:
359 lua_pop(L, 1);
360 // check if nested:
361 if (--level) {
362 // if nested,
363 // check if outer(!) structure is an array or object:
364 if (lua_isnil(L, -2)) {
365 // select array value processing:
366 mode = JSON_STATE_ARRAY_VALUE;
367 } else {
368 // select object value processing:
369 mode = JSON_STATE_OBJECT_VALUE;
370 }
371 // store value in outer structure:
372 goto json_import_process_value;
373 }
374 // if not nested, then expect end of JSON document and continue with loop:
375 mode = JSON_STATE_END;
376 goto json_import_loop;
377 // key terminator:
378 case ':':
379 // if key terminator is not expected here, then return an error:
380 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
381 goto json_import_syntax_error;
382 // consume input character:
383 pos++;
384 // expect object value to follow:
385 mode = JSON_STATE_OBJECT_VALUE;
386 // continue with loop:
387 goto json_import_loop;
388 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
389 case ',':
390 // branch according to parser state:
391 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
392 // expect an object key to follow:
393 mode = JSON_STATE_OBJECT_KEY;
394 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
395 // expect an array value to follow:
396 mode = JSON_STATE_ARRAY_VALUE;
397 } else {
398 // if value terminator is not expected here, then return an error:
399 goto json_import_syntax_error;
400 }
401 // consume input character:
402 pos++;
403 // continue with loop:
404 goto json_import_loop;
405 // string literal:
406 case '"':
407 // consume quote character:
408 pos++;
409 // find last character in input string:
410 outlen = pos;
411 while ((c = str[outlen]) != '"') {
412 // consume one character:
413 outlen++;
414 // handle unexpected end of JSON document:
415 if (c == 0) goto json_import_unexpected_eof;
416 // consume one extra character when encountering an escaped quote:
417 else if (c == '\\' && str[outlen] == '"') outlen++;
418 }
419 // determine buffer length:
420 outlen -= pos;
421 // check if string is non empty:
422 if (outlen) {
423 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
424 cbuf = luaL_buffinitsize(L, &luabuf, outlen);
425 outlen = 0;
426 // loop through the characters until encountering end quote:
427 while ((c = str[pos++]) != '"') {
428 // NOTE: unexpected end cannot happen anymore
429 if (c < 32 || c == 127) {
430 // do not allow ASCII control characters:
431 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
432 // by this parser to allow different encodings than Unicode
433 lua_pushnil(L);
434 lua_pushliteral(L, "Unexpected control character in JSON string");
435 return 2;
436 } else if (c == '\\') {
437 // read next char after backslash escape:
438 c = str[pos++];
439 switch (c) {
440 // unexpected end-of-string:
441 case 0:
442 goto json_import_unexpected_eof;
443 // unescaping of quotation mark, slash, and backslash:
444 case '"':
445 case '/':
446 case '\\':
447 cbuf[outlen++] = c;
448 break;
449 // unescaping of backspace:
450 case 'b': cbuf[outlen++] = '\b'; break;
451 // unescaping of form-feed:
452 case 'f': cbuf[outlen++] = '\f'; break;
453 // unescaping of new-line:
454 case 'n': cbuf[outlen++] = '\n'; break;
455 // unescaping of carriage-return:
456 case 'r': cbuf[outlen++] = '\r'; break;
457 // unescaping of tabulator:
458 case 't': cbuf[outlen++] = '\t'; break;
459 // unescaping of UTF-16 characters
460 case 'u':
461 // decode 4 hex nibbles:
462 json_import_readhex(codepoint);
463 // handle surrogate character:
464 if (json_utf16_surrogate(codepoint)) {
465 // check if first surrogate is in valid range:
466 if (json_utf16_lead(codepoint)) {
467 // require second surrogate:
468 if ((c = str[pos++]) != '\\' || (c = str[pos++]) != 'u') {
469 if (c == 0) goto json_import_unexpected_eof;
470 else goto json_import_wrong_surrogate;
471 }
472 // read 4 hex nibbles of second surrogate character:
473 json_import_readhex(utf16tail);
474 // check if second surrogate is in valid range:
475 if (!json_utf16_tail(utf16tail)) goto json_import_wrong_surrogate;
476 // calculate codepoint:
477 codepoint = 0x10000 + (utf16tail - 0xDC00) + (codepoint - 0xD800) * 0x400;
478 } else {
479 // throw error for wrong surrogates:
480 json_import_wrong_surrogate:
481 lua_pushnil(L);
482 lua_pushliteral(L, "Illegal UTF-16 surrogate in JSON string escape sequence");
483 return 2;
484 }
485 }
486 // encode as UTF-8:
487 if (codepoint < 0x80) {
488 cbuf[outlen++] = (char)codepoint;
489 } else if (codepoint < 0x800) {
490 cbuf[outlen++] = (char)(0xc0 | (codepoint >> 6));
491 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
492 } else if (codepoint < 0x10000) {
493 cbuf[outlen++] = (char)(0xe0 | (codepoint >> 12));
494 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 6) & 0x3f));
495 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
496 } else {
497 cbuf[outlen++] = (char)(0xf0 | (codepoint >> 18));
498 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 12) & 0x3f));
499 cbuf[outlen++] = (char)(0x80 | ((codepoint >> 6) & 0x3f));
500 cbuf[outlen++] = (char)(0x80 | (codepoint & 0x3f));
501 }
502 break;
503 // unexpected escape sequence:
504 default:
505 json_import_unexpected_escape:
506 lua_pushnil(L);
507 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
508 return 2;
509 }
510 } else {
511 // normal character:
512 cbuf[outlen++] = c;
513 }
514 }
515 // process buffer to Lua string:
516 luaL_pushresultsize(&luabuf, outlen);
517 } else {
518 // if JSON string is empty,
519 // push empty Lua string:
520 lua_pushliteral(L, "");
521 // consume closing quote:
522 pos++;
523 }
524 // continue with processing of decoded string:
525 goto json_import_process_value;
526 }
527 // process values whose type is is not deducible from a single character:
528 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
529 // for numbers,
530 // use strtod() call to parse a (double precision) floating point number:
531 double numval;
532 char *endptr;
533 numval = strtod(str+pos, &endptr);
534 // catch parsing errors:
535 if (endptr == str+pos) goto json_import_syntax_error;
536 // consume characters that were parsed:
537 pos += endptr - (str+pos);
538 // push parsed (double precision) floating point number on Lua stack:
539 lua_pushnumber(L, numval);
540 } else if (!strncmp(str+pos, "true", 4)) {
541 // consume 4 input characters for "true":
542 pos += 4;
543 // put Lua true value onto stack:
544 lua_pushboolean(L, 1);
545 } else if (!strncmp(str+pos, "false", 5)) {
546 // consume 5 input characters for "false":
547 pos += 5;
548 // put Lua false value onto stack:
549 lua_pushboolean(L, 0);
550 } else if (!strncmp(str+pos, "null", 4)) {
551 // consume 4 input characters for "null":
552 pos += 4;
553 // different behavor for top-level and sub-levels:
554 if (level) {
555 // if sub-level,
556 // push special null-marker onto stack:
557 json_pushnullmark(L);
558 } else {
559 // if top-level,
560 // push nil onto stack:
561 lua_pushnil(L);
562 }
563 } else {
564 // all other cases are a syntax error:
565 goto json_import_syntax_error;
566 }
567 // process a decoded value or key value pair (expected on top of Lua stack):
568 json_import_process_value:
569 switch (mode) {
570 // an object key has been read:
571 case JSON_STATE_OBJECT_KEY:
572 // if an object key is not a string, then this is a syntax error:
573 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
574 // expect key terminator to follow:
575 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
576 // continue with loop:
577 goto json_import_loop;
578 // a key value pair has been read:
579 case JSON_STATE_OBJECT_VALUE:
580 // store key value pair in outer shadow table:
581 lua_rawset(L, -3);
582 // expect value terminator (or end of object) to follow:
583 mode = JSON_STATE_OBJECT_SEPARATOR;
584 // continue with loop:
585 goto json_import_loop;
586 // an array value has been read:
587 case JSON_STATE_ARRAY_VALUE:
588 // get current array length:
589 arraylen = lua_rawlen(L, -3);
590 // throw error if array would exceed INT_MAX elements:
591 // TODO: Lua 5.3 may support more elements
592 if (arraylen >= INT_MAX) {
593 lua_pushnil(L);
594 lua_pushfstring(L, "Array exceeded length of %d elements", INT_MAX);
595 }
596 // store value in outer shadow table:
597 lua_rawseti(L, -3, arraylen + 1);
598 // expect value terminator (or end of object) to follow:
599 mode = JSON_STATE_ARRAY_SEPARATOR;
600 // continue with loop
601 goto json_import_loop;
602 // a single value has been read:
603 case JSON_STATE_VALUE:
604 // leave value on top of stack, expect end of JSON document, and continue with loop:
605 mode = JSON_STATE_END;
606 goto json_import_loop;
607 }
608 // syntax error handling (reachable by goto statement):
609 json_import_syntax_error:
610 lua_pushnil(L);
611 lua_pushliteral(L, "Syntax error in JSON document");
612 return 2;
613 }
615 // special Lua stack indicies for json_path function:
616 #define json_path_shadowtbl_idx 1
618 // stack offset of arguments to json_path function:
619 #define json_path_idxshift 1
621 // gets a value or its type from a JSON document (passed as first argument)
622 // using a path (passed as variable number of keys after the first argument):
623 static int json_path(lua_State *L, int type_mode) {
624 int stacktop; // stack index of top of stack (after shifting)
625 int idx = 2 + json_path_idxshift; // stack index of current argument to process
626 // require at least one argument:
627 luaL_checkany(L, 1);
628 // insert shadowtbl into stack at position 1 (shifting the arguments):
629 json_regfetch(L, shadowtbl);
630 lua_insert(L, 1);
631 // store stack index of top of stack:
632 stacktop = lua_gettop(L);
633 // use first argument as "current value" (stored on top of stack):
634 lua_pushvalue(L, 1 + json_path_idxshift);
635 // process each "path key" (2nd argument and following arguments):
636 while (idx <= stacktop) {
637 // if "current value" (on top of stack) is nil, then the path cannot be walked and nil is returned:
638 if (lua_isnil(L, -1)) return 1;
639 // try to get shadow table of "current value":
640 lua_pushvalue(L, -1);
641 lua_rawget(L, json_path_shadowtbl_idx);
642 if (lua_isnil(L, -1)) {
643 // if no shadow table is found,
644 if (lua_type(L, -1) == LUA_TTABLE) {
645 // and if "current value" is a table,
646 // drop nil from stack:
647 lua_pop(L, 1);
648 // get "next value" using the "path key":
649 lua_pushvalue(L, idx++);
650 lua_gettable(L, -2);
651 } else {
652 // if "current value" is not a table,
653 // then the path cannot be walked and nil (already on top of stack) is returned:
654 return 1;
655 }
656 } else {
657 // if a shadow table is found,
658 // set "current value" to its shadow table:
659 lua_replace(L, -2);
660 // get "next value" using the "path key":
661 lua_pushvalue(L, idx++);
662 lua_rawget(L, -2);
663 }
664 // the "next value" replaces the "current value":
665 lua_replace(L, -2);
666 }
667 if (!type_mode) {
668 // if a value (and not its type) was requested,
669 // check if value is the null-marker, and store nil on top of Lua stack in that case:
670 if (json_isnullmark(L, -1)) lua_pushnil(L);
671 } else {
672 // if the type was requested,
673 // check if value is the null-marker:
674 if (json_isnullmark(L, -1)) {
675 // if yes, store string "null" on top of Lua stack:
676 lua_pushliteral(L, "null");
677 } else {
678 // otherwise,
679 // check if metatable indicates "object" or "array":
680 if (lua_getmetatable(L, -1)) {
681 json_regfetch(L, objectmt);
682 if (lua_rawequal(L, -2, -1)) {
683 // if value has metatable for JSON objects,
684 // return string "object":
685 lua_pushliteral(L, "object");
686 return 1;
687 }
688 json_regfetch(L, arraymt);
689 if (lua_rawequal(L, -3, -1)) {
690 // if value has metatable for JSON arrays,
691 // return string "object":
692 lua_pushliteral(L, "array");
693 return 1;
694 }
695 // remove 3 metatables (one of the value, two for comparison) from stack:
696 lua_pop(L, 3);
697 }
698 // otherwise, get the Lua type:
699 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
700 }
701 }
702 // return the top most value on the Lua stack:
703 return 1;
704 }
706 // gets a value from a JSON document (passed as first argument)
707 // using a path (passed as variable number of keys after the first argument):
708 static int json_get(lua_State *L) {
709 return json_path(L, 0);
710 }
712 // gets a value's type from a JSON document (passed as first argument)
713 // using a path (passed as variable number of keys after first the argument):
714 static int json_type(lua_State *L) {
715 return json_path(L, 1);
716 }
718 // special Lua stack indicies for json_set function:
719 #define json_set_shadowtbl_idx 1
720 #define json_set_objectmt_idx 2
721 #define json_set_arraymt_idx 3
723 // stack offset of arguments to json_set function:
724 #define json_set_idxshift 3
726 // sets a value (passed as second argument) in a JSON document (passed as first argument)
727 // using a path (passed as variable number of keys starting at third argument):
728 static int json_set(lua_State *L) {
729 int stacktop; // stack index of top of stack (after shifting)
730 int idx = 3; // stack index of current argument to process
731 // require at least two arguments:
732 luaL_checkany(L, 1);
733 luaL_checkany(L, 2);
734 // insert shadowtbl into stack at position 1 (shifting the arguments):
735 json_regfetch(L, shadowtbl);
736 lua_insert(L, 1);
737 // insert objectmt into stack at position 2 (shifting the arguments):
738 json_regfetch(L, objectmt);
739 lua_insert(L, 2);
740 // insert arraymt into stack at position 3 (shifting the arguments):
741 json_regfetch(L, arraymt);
742 lua_insert(L, 3);
743 // store stack index of top of stack:
744 stacktop = lua_gettop(L);
745 // use nil as initial "parent value":
746 lua_pushnil(L);
747 // use first argument as "current value":
748 lua_pushvalue(L, 1 + json_set_idxshift);
749 // set all necessary values in path:
750 for (idx = 3 + json_set_idxshift; idx<=stacktop; idx++) {
751 // push metatable of "current value" onto stack:
752 if (!lua_getmetatable(L, -1)) lua_pushnil(L);
753 // distinguish according to type of path key:
754 switch (lua_type(L, idx)) {
755 case LUA_TSTRING:
756 // if path key is a string,
757 // check if "current value" is a JSON object (or table without metatable):
758 if (
759 lua_rawequal(L, -1, json_set_objectmt_idx) ||
760 (lua_isnil(L, -1) && lua_type(L, -2) == LUA_TTABLE)
761 ) {
762 // if "current value" is acceptable,
763 // pop metatable and leave "current value" on top of stack:
764 lua_pop(L, 1);
765 } else {
766 // if "current value" is not acceptable:
767 // pop metatable and "current value":
768 lua_pop(L, 2);
769 // throw error if parent element does not exist:
770 if (lua_isnil(L, -1)) return luaL_error(L, "Root element is not a JSON object");
771 // push new JSON object as "current value" onto stack:
772 lua_newtable(L);
773 // create and register shadow table:
774 lua_pushvalue(L, -1);
775 lua_newtable(L);
776 lua_rawset(L, json_set_shadowtbl_idx);
777 // set metatable of JSON object:
778 lua_pushvalue(L, json_set_objectmt_idx);
779 lua_setmetatable(L, -2);
780 // set entry in "parent value":
781 lua_pushvalue(L, idx-1);
782 lua_pushvalue(L, -2);
783 lua_settable(L, -4);
784 }
785 break;
786 case LUA_TNUMBER:
787 // if path key is a number,
788 // check if "current value" is a JSON array (or table without metatable):
789 if (
790 lua_rawequal(L, -1, json_set_arraymt_idx) ||
791 (lua_isnil(L, -1) && lua_type(L, -2) == LUA_TTABLE)
792 ) {
793 // if "current value" is acceptable,
794 // pop metatable and leave "current value" on top of stack:
795 lua_pop(L, 1);
796 } else {
797 // if "current value" is not acceptable:
798 // pop metatable and "current value":
799 lua_pop(L, 2);
800 // throw error if parent element does not exist:
801 if (lua_isnil(L, -1)) return luaL_error(L, "Root element is not a JSON array");
802 // push new JSON array as "current value" onto stack:
803 lua_newtable(L);
804 // create and register shadow table:
805 lua_pushvalue(L, -1);
806 lua_newtable(L);
807 lua_rawset(L, json_set_shadowtbl_idx);
808 // set metatable of JSON array:
809 lua_pushvalue(L, json_set_arraymt_idx);
810 lua_setmetatable(L, -2);
811 // set entry in "parent value":
812 lua_pushvalue(L, idx-1);
813 lua_pushvalue(L, -2);
814 lua_settable(L, -4);
815 }
816 break;
817 default:
818 return luaL_error(L, "Invalid path key of type %s", lua_typename(L, lua_type(L, idx)));
819 }
820 // check if last path element is being processed:
821 if (idx == stacktop) {
822 // if the last path element is being processed,
823 // set last path value in "current value" container:
824 lua_pushvalue(L, idx);
825 lua_pushvalue(L, 2 + json_set_idxshift);
826 lua_settable(L, -3);
827 } else {
828 // if the processed path element is not the last,
829 // use old "current value" as new "parent value"
830 lua_remove(L, -2);
831 // push new "current value" onto stack by performing a lookup:
832 lua_pushvalue(L, idx);
833 lua_gettable(L, -2);
834 }
835 }
836 // return first argument for convenience:
837 lua_settop(L, 1 + json_set_idxshift);
838 return 1;
839 }
841 // returns the length of a JSON array (or zero for a table without numeric keys):
842 static int json_len(lua_State *L) {
843 // stack shall contain one function argument:
844 lua_settop(L, 1);
845 // try to get corresponding shadow table for first argument:
846 json_regfetch(L, shadowtbl);
847 lua_pushvalue(L, 1);
848 lua_rawget(L, -2);
849 // if shadow table does not exist, return length of argument, else length of shadow table:
850 lua_pushnumber(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
851 return 1;
852 }
854 // __index metamethod for JSON objects and JSON arrays:
855 static int json_index(lua_State *L) {
856 // stack shall contain two function arguments:
857 lua_settop(L, 2);
858 // get corresponding shadow table for first argument:
859 json_regfetch(L, shadowtbl);
860 lua_pushvalue(L, 1);
861 lua_rawget(L, -2);
862 // throw error if no shadow table was found:
863 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
864 // use key passed as second argument to lookup value in shadow table:
865 lua_pushvalue(L, 2);
866 lua_rawget(L, -2);
867 // if value is null-marker, then push nil onto stack:
868 if (json_isnullmark(L, -1)) lua_pushnil(L);
869 // return either looked up value, or nil
870 return 1;
871 }
873 // __newindex metamethod for JSON objects and JSON arrays:
874 static int json_newindex(lua_State *L) {
875 // stack shall contain three function arguments:
876 lua_settop(L, 3);
877 // get corresponding shadow table for first argument:
878 json_regfetch(L, shadowtbl);
879 lua_pushvalue(L, 1);
880 lua_rawget(L, -2);
881 // throw error if no shadow table was found:
882 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
883 // replace first argument with shadow table:
884 lua_replace(L, 1);
885 // reset stack and use second and third argument to write to shadow table:
886 lua_settop(L, 3);
887 lua_rawset(L, 1);
888 // return nothing:
889 return 0;
890 }
892 // function returned as first value by json_pairs function:
893 static int json_pairs_iterfunc(lua_State *L) {
894 // stack shall contain two function arguments:
895 lua_settop(L, 2);
896 // get corresponding shadow table for first argument:
897 json_regfetch(L, shadowtbl);
898 lua_pushvalue(L, 1);
899 lua_rawget(L, -2);
900 // throw error if no shadow table was found:
901 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
902 // get next key value pair from shadow table (using previous key from argument 2)
903 // and return nothing if there is no next pair:
904 lua_pushvalue(L, 2);
905 if (!lua_next(L, -2)) return 0;
906 // replace null-marker with nil:
907 if (json_isnullmark(L, -1)) {
908 lua_pop(L, 1);
909 lua_pushnil(L);
910 }
911 // return key and value (or key and nil, if null-marker was found):
912 return 2;
913 }
915 // returns a triple such that 'for key, value in pairs(obj) do ... end'
916 // iterates through all key value pairs (including JSON null values represented as Lua nil):
917 static int json_pairs(lua_State *L) {
918 // require one argument to function
919 luaL_checkany(L, 1);
920 // return triple of function json_pairs_iterfunc, first argument, and nil:
921 lua_pushcfunction(L, json_pairs_iterfunc);
922 lua_pushvalue(L, 1);
923 lua_pushnil(L);
924 return 3;
925 }
927 // function returned as first value by json_ipairs function:
928 static int json_ipairs_iterfunc(lua_State *L) {
929 lua_Integer idx;
930 // stack shall contain two function arguments:
931 lua_settop(L, 2);
932 // calculate new index by incrementing second argument:
933 idx = lua_tointeger(L, 2) + 1;
934 // get corresponding shadow table for first argument:
935 json_regfetch(L, shadowtbl);
936 lua_pushvalue(L, 1);
937 lua_rawget(L, -2);
938 // throw error if no shadow table was found:
939 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
940 // do integer lookup in shadow table:
941 lua_rawgeti(L, -1, idx);
942 // return nothing if there was no value:
943 if (lua_isnil(L, -1)) return 0;
944 // return new index and
945 // either the looked up value if it is not equal to the null-marker
946 // or nil instead of null-marker:
947 lua_pushinteger(L, idx);
948 if (json_isnullmark(L, -2)) lua_pushnil(L);
949 else lua_pushvalue(L, -2);
950 return 2;
951 }
953 // returns a triple such that 'for idx, value in ipairs(ary) do ... end'
954 // iterates through all values (including JSON null values represented as Lua nil):
955 static int json_ipairs(lua_State *L) {
956 // require one argument to function
957 luaL_checkany(L, 1);
958 // return triple of function json_ipairs_iterfunc, first argument, and zero:
959 lua_pushcfunction(L, json_ipairs_iterfunc);
960 lua_pushvalue(L, 1);
961 lua_pushinteger(L, 0);
962 return 3;
963 }
965 // datatype representing a table key:
966 // (used for sorting)
967 typedef struct {
968 size_t length;
969 const char *data;
970 } json_key_t;
972 // comparation function for table keys to be passed to qsort function:
973 static int json_key_cmp(json_key_t *key1, json_key_t *key2) {
974 size_t pos = 0;
975 unsigned char c1, c2;
976 while (1) {
977 if (key1->length > pos) {
978 if (key2->length > pos) {
979 c1 = key1->data[pos];
980 c2 = key2->data[pos];
981 if (c1 < c2) return -1;
982 else if (c1 > c2) return 1;
983 } else {
984 return 1;
985 }
986 } else {
987 if (key2->length > pos) {
988 return -1;
989 } else {
990 return 0;
991 }
992 }
993 pos++;
994 }
995 }
997 // constants for type detection of ambiguous tables:
998 #define JSON_TABLETYPE_UNKNOWN 0
999 #define JSON_TABLETYPE_OBJECT 1
1000 #define JSON_TABLETYPE_ARRAY 2
1002 // special Lua stack indicies for json_export_internal function:
1003 #define json_export_internal_indentstring_idx 1
1004 #define json_export_internal_level_idx 2
1005 #define json_export_internal_value_idx 3
1006 #define json_export_internal_tmp_idx 4
1008 // encodes a JSON document (passed as third argument)
1009 // optionally using indentation (indentation string passed as first argument)
1010 // for a certain depth level (passed as second argument):
1011 static int json_export_internal(lua_State *L) {
1012 int level; // current depth level
1013 int pretty; // pretty printing on? (i.e. printing with indentation)
1014 int i; // iteration variable for level dependent repetitions:
1015 lua_Number num; // number to encode
1016 const char *str; // string to encode
1017 size_t strlen; // length of string to encode
1018 unsigned char c; // character to encode (unsigned!)
1019 size_t pos = 0; // position in string or position of current key (initialized with zero!)
1020 luaL_Buffer buf; // Lua buffer to create strings
1021 char hexcode[7]; // store for unicode hex escape sequence
1022 // NOTE: 7 bytes due to backslash, character 'u', 4 hex digits, and terminating NULL byte
1023 int tabletype = JSON_TABLETYPE_UNKNOWN; // table type: unknown, JSON object, or JSON array
1024 int anyelement = 0; // set to 1 if at least one array element has been processed
1025 size_t keycount = 0; // number of string keys in object
1026 json_key_t *keybuf = NULL; // temporary buffer to store (and sort) string keys of objects
1027 lua_Integer arrayidx; // index to iterate through arrays
1028 // stack shall contain three function arguments:
1029 lua_settop(L, json_export_internal_value_idx);
1030 // if value to encode is the null-marker, then treat it the same as nil:
1031 if (json_isnullmark(L, json_export_internal_value_idx)) {
1032 lua_pop(L, 1);
1033 lua_pushnil(L);
1034 }
1035 // distinguish between different Lua types:
1036 switch (lua_type(L, json_export_internal_value_idx)) {
1037 // value to encode is nil:
1038 case LUA_TNIL:
1039 // return string "null":
1040 lua_pushliteral(L, "null");
1041 return 1;
1042 // value to encode is of type number:
1043 case LUA_TNUMBER:
1044 // convert value to double precision number:
1045 num = lua_tonumber(L, json_export_internal_value_idx);
1046 // throw error if number is not-a-number:
1047 if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
1048 // throw error if number is positive or negative infinity:
1049 if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
1050 // return Lua's string encoding of the number:
1051 lua_tostring(L, json_export_internal_value_idx);
1052 return 1;
1053 // value to encode is of type boolean:
1054 case LUA_TBOOLEAN:
1055 // return string "true" or "false" according to boolean value:
1056 if (lua_toboolean(L, json_export_internal_value_idx)) {
1057 lua_pushliteral(L, "true");
1058 } else {
1059 lua_pushliteral(L, "false");
1060 }
1061 return 1;
1062 // value to encode is of type string:
1063 case LUA_TSTRING:
1064 // quote, escape and return string:
1065 str = lua_tolstring(L, 3, &strlen);
1066 luaL_buffinit(L, &buf);
1067 luaL_addchar(&buf, '"');
1068 while (pos < strlen) {
1069 c = str[pos++];
1070 if (c == '"') luaL_addstring(&buf, "\\\"");
1071 else if (c == '\\') luaL_addstring(&buf, "\\\\");
1072 else if (c == 127) luaL_addstring(&buf, "\\u007F");
1073 else if (c >= 32) luaL_addchar(&buf, c);
1074 else if (c == '\b') luaL_addstring(&buf, "\\b");
1075 else if (c == '\f') luaL_addstring(&buf, "\\f");
1076 else if (c == '\n') luaL_addstring(&buf, "\\n");
1077 else if (c == '\r') luaL_addstring(&buf, "\\r");
1078 else if (c == '\t') luaL_addstring(&buf, "\\t");
1079 else if (c == '\v') luaL_addstring(&buf, "\\v");
1080 else {
1081 sprintf(hexcode, "\\u%04X", c);
1082 luaL_addstring(&buf, hexcode);
1083 }
1084 }
1085 luaL_addchar(&buf, '"');
1086 luaL_pushresult(&buf);
1087 return 1;
1088 // value to encode is of type table (this includes JSON objects and JSON arrays):
1089 case LUA_TTABLE:
1090 // use table's metatable to try to determine type of table:
1091 if (lua_getmetatable(L, json_export_internal_value_idx)) {
1092 json_regfetch(L, objectmt);
1093 if (lua_rawequal(L, -2, -1)) {
1094 tabletype = JSON_TABLETYPE_OBJECT;
1095 } else {
1096 json_regfetch(L, arraymt);
1097 if (lua_rawequal(L, -3, -1)) {
1098 tabletype = JSON_TABLETYPE_ARRAY;
1099 } else {
1100 return luaL_error(L, "JSON export not possible for tables with nonsupported metatable");
1101 }
1102 }
1103 }
1104 // replace table with its shadow table if existent, and reset stack:
1105 json_regfetch(L, shadowtbl);
1106 lua_pushvalue(L, json_export_internal_value_idx);
1107 lua_rawget(L, -2);
1108 if (!lua_isnil(L, -1)) lua_replace(L, json_export_internal_value_idx);
1109 lua_settop(L, json_export_internal_value_idx);
1110 // check if type of table is still undetermined:
1111 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
1112 // if yes, iterate over all keys:
1113 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1114 switch (lua_type(L, -2)) {
1115 case LUA_TSTRING:
1116 // for string keys,
1117 // increase keycount (may avoid another iteration):
1118 keycount++;
1119 // if type of table was unknown, then type of table is a JSON object now:
1120 if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_OBJECT;
1121 // if type of table was a JSON array, then the type of table is ambiguous now
1122 // and an error is thrown:
1123 else if (tabletype == JSON_TABLETYPE_ARRAY) goto json_export_tabletype_error;
1124 break;
1125 case LUA_TNUMBER:
1126 // for numeric keys,
1127 // if type of table was unknown, then type of table is a JSON array now:
1128 if (tabletype == JSON_TABLETYPE_UNKNOWN) tabletype = JSON_TABLETYPE_ARRAY;
1129 // if type of table was a JSON object, then the type of table is ambiguous now
1130 // and an error is thrown:
1131 else if (tabletype == JSON_TABLETYPE_OBJECT) goto json_export_tabletype_error;
1132 break;
1133 }
1134 }
1135 }
1136 // set pretty variable to 1 if pretty printing (with indentation) is desired:
1137 pretty = lua_toboolean(L, json_export_internal_indentstring_idx);
1138 // set level variable to corresponding function argument increased by one:
1139 level = lua_tointeger(L, json_export_internal_level_idx) + 1;
1140 // throw error if there are more levels that could be imported by this library:
1141 if (level > JSON_MAXDEPTH) {
1142 return luaL_error(L, "More than %d nested JSON levels", JSON_MAXDEPTH);
1143 }
1144 // distinguish between JSON objects and JSON arrays:
1145 switch (tabletype) {
1146 // JSON object:
1147 case JSON_TABLETYPE_OBJECT:
1148 // calculate count of string keys unless it has been calculated before:
1149 if (!keycount) {
1150 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1151 if (lua_type(L, -2) == LUA_TSTRING) keycount++;
1152 }
1153 }
1154 // create a sorted list of all string keys in memory:
1155 if (keycount) {
1156 // allocate memory for string keys:
1157 keybuf = calloc(keycount, sizeof(json_key_t));
1158 // check if memory allocation was successful:
1159 if (!keybuf) {
1160 // in case of memory exhaustion, try to collect garbage:
1161 lua_gc(L, LUA_GCCOLLECT, 0);
1162 // try to allocate memory again:
1163 keybuf = calloc(keycount, sizeof(json_key_t));
1164 // throw error if memory allocation failed again:
1165 if (!keybuf) {
1166 return luaL_error(L, "Memory allocation failed in JSON library");
1167 }
1168 }
1169 // copy all string keys to the C array:
1170 for (lua_pushnil(L); lua_next(L, json_export_internal_value_idx); lua_pop(L, 1)) {
1171 if (lua_type(L, -2) == LUA_TSTRING) {
1172 json_key_t *key = keybuf + (pos++);
1173 key->data = lua_tolstring(L, -2, &key->length);
1174 }
1175 }
1176 // sort C array using quicksort:
1177 qsort(keybuf, keycount, sizeof(json_key_t), (void *)json_key_cmp);
1178 }
1179 // create Lua string buffer:
1180 luaL_buffinit(L, &buf);
1181 // add opening bracket to output buffer:
1182 luaL_addchar(&buf, '{');
1183 // iterate through all (sorted) string keys:
1184 for (pos=0; pos<keycount; pos++) {
1185 json_key_t *key = keybuf + pos;
1186 // add comma to output buffer unless we process the first key:
1187 if (pos) luaL_addchar(&buf, ',');
1188 // handle indentation for pretty results:
1189 if (pretty) {
1190 luaL_addchar(&buf, '\n');
1191 for (i=0; i<level; i++) {
1192 lua_pushvalue(L, json_export_internal_indentstring_idx);
1193 luaL_addvalue(&buf);
1194 }
1195 }
1196 // recursive call to encode key:
1197 lua_pushcfunction(L, json_export_internal);
1198 lua_pushvalue(L, json_export_internal_indentstring_idx);
1199 lua_pushinteger(L, level);
1200 lua_pushlstring(L, key->data, key->length);
1201 if (lua_pcall(L, 3, 1, 0)) {
1202 // free memory of sorted string keys on error:
1203 if (keybuf) free(keybuf);
1204 // rethrow error:
1205 return lua_error(L);
1206 }
1207 // add encoded key to output buffer:
1208 luaL_addvalue(&buf);
1209 // add colon to output buffer:
1210 luaL_addchar(&buf, ':');
1211 // handle indentation for pretty results:
1212 if (pretty) luaL_addchar(&buf, ' ');
1213 // recursive call to encode value:
1214 lua_pushcfunction(L, json_export_internal);
1215 lua_pushvalue(L, json_export_internal_indentstring_idx);
1216 lua_pushinteger(L, level);
1217 lua_pushlstring(L, key->data, key->length);
1218 lua_rawget(L, json_export_internal_value_idx);
1219 if (lua_pcall(L, 3, 1, 0)) {
1220 // free memory of sorted string keys on error:
1221 if (keybuf) free(keybuf);
1222 // rethrow error:
1223 return lua_error(L);
1224 }
1225 // add encoded value to output buffer:
1226 luaL_addvalue(&buf);
1227 }
1228 // decrement level variable for all following statements:
1229 level--;
1230 // free memory of sorted string keys:
1231 if (keybuf) free(keybuf);
1232 // handle indentation for pretty results:
1233 if (pretty && keycount != 0) {
1234 luaL_addchar(&buf, '\n');
1235 for (i=0; i<level; i++) {
1236 lua_pushvalue(L, json_export_internal_indentstring_idx);
1237 luaL_addvalue(&buf);
1238 }
1239 }
1240 // add closing bracket to output buffer:
1241 luaL_addchar(&buf, '}');
1242 // for pretty results, add final newline character if outermost container is processed:
1243 if (pretty && level == 0) luaL_addchar(&buf, '\n');
1244 // convert and return buffer:
1245 luaL_pushresult(&buf);
1246 return 1;
1247 // JSON array:
1248 case JSON_TABLETYPE_ARRAY:
1249 // reserve an extra element on the stack (needed because Lua buffer has unknown size on stack):
1250 lua_settop(L, json_export_internal_tmp_idx);
1251 // create Lua string buffer:
1252 luaL_buffinit(L, &buf);
1253 // add opening bracket to output buffer:
1254 luaL_addchar(&buf, '[');
1255 // iterate through integer keys:
1256 for (arrayidx = 1; ; arrayidx++) {
1257 // get value in array, and break if nil:
1258 lua_rawgeti(L, json_export_internal_value_idx, arrayidx);
1259 if (lua_isnil(L, -1)) {
1260 lua_pop(L, 1);
1261 break;
1262 }
1263 // store value below Lua string buffer on stack (to allow operation on string buffer):
1264 lua_replace(L, json_export_internal_tmp_idx);
1265 //
1266 // add comma to output buffer unless we process the first element:
1267 if (anyelement) luaL_addchar(&buf, ',');
1268 // remember that we processed an element:
1269 anyelement = 1;
1270 // handle indentation for pretty results:
1271 if (pretty) {
1272 luaL_addchar(&buf, '\n');
1273 for (i=0; i<level; i++) {
1274 lua_pushvalue(L, json_export_internal_indentstring_idx);
1275 luaL_addvalue(&buf);
1276 }
1277 }
1278 // recursive call to encode previously stored value:
1279 lua_pushcfunction(L, json_export_internal);
1280 lua_pushvalue(L, json_export_internal_indentstring_idx);
1281 lua_pushinteger(L, level);
1282 lua_pushvalue(L, json_export_internal_tmp_idx);
1283 lua_call(L, 3, 1);
1284 // add encoded value to output buffer:
1285 luaL_addvalue(&buf);
1286 }
1287 // decrement level variable for all following statements:
1288 level--;
1289 // handle indentation for pretty results:
1290 if (pretty && anyelement) {
1291 luaL_addchar(&buf, '\n');
1292 for (i=0; i<level; i++) {
1293 lua_pushvalue(L, json_export_internal_indentstring_idx);
1294 luaL_addvalue(&buf);
1295 }
1296 }
1297 // add closing bracket to output buffer:
1298 luaL_addchar(&buf, ']');
1299 // for pretty results, add final newline character if outermost container is processed:
1300 if (pretty && level == 0) luaL_addchar(&buf, '\n');
1301 // convert and return buffer:
1302 luaL_pushresult(&buf);
1303 return 1;
1304 }
1305 // throw error if table type is unknown:
1306 json_export_tabletype_error:
1307 return luaL_error(L, "JSON export not possible for ambiguous table (cannot decide whether it is an object or array)");
1308 }
1309 // all other datatypes are considered an error:
1310 return luaL_error(L, "JSON export not possible for values of type \"%s\"", lua_typename(L, lua_type(L, json_export_internal_value_idx)));
1311 }
1313 // encodes a JSON document (passed as argument):
1314 static int json_export(lua_State *L) {
1315 // stack shall contain one function argument:
1316 lua_settop(L, 1);
1317 // call json_export_internal function with proper arguments:
1318 lua_pushcfunction(L, json_export_internal);
1319 lua_pushnil(L);
1320 lua_pushinteger(L, 0);
1321 lua_pushvalue(L, 1);
1322 lua_call(L, 3, 1);
1323 // return result:
1324 return 1;
1325 }
1327 // encodes a JSON document (passed as first argument)
1328 // with indentation (indentation string may be passed as second argument):
1329 static int json_pretty(lua_State *L) {
1330 // stack shall contain two function arguments:
1331 lua_settop(L, 2);
1332 // call json_export_internal function with proper arguments:
1333 lua_pushcfunction(L, json_export_internal);
1334 if (lua_isnil(L, 2)) lua_pushliteral(L, " ");
1335 else lua_pushvalue(L, 2);
1336 lua_pushinteger(L, 0);
1337 lua_pushvalue(L, 1);
1338 lua_call(L, 3, 1);
1339 // return result:
1340 return 1;
1341 }
1343 // functions in library module:
1344 static const struct luaL_Reg json_module_functions[] = {
1345 {"object", json_object},
1346 {"array", json_array},
1347 {"import", json_import},
1348 {"export", json_export},
1349 {"pretty", json_pretty},
1350 {"get", json_get},
1351 {"type", json_type},
1352 {"set", json_set},
1353 {NULL, NULL}
1354 };
1356 // metamethods for JSON objects, JSON arrays, and unknown JSON collections (object or array):
1357 static const struct luaL_Reg json_metatable_functions[] = {
1358 {"__len", json_len},
1359 {"__index", json_index},
1360 {"__newindex", json_newindex},
1361 {"__pairs", json_pairs},
1362 {"__ipairs", json_ipairs},
1363 {"__tostring", json_export},
1364 {NULL, NULL}
1365 };
1367 // metamethods for JSON null marker:
1368 static const struct luaL_Reg json_nullmark_metamethods[] = {
1369 {"__tostring", json_nullmark_tostring},
1370 {NULL, NULL}
1371 };
1373 // initializes json library:
1374 int luaopen_json(lua_State *L) {
1375 // empty stack:
1376 lua_settop(L, 0);
1377 // push library module onto stack position 1:
1378 lua_newtable(L);
1379 // register library functions:
1380 luaL_setfuncs(L, json_module_functions, 0);
1381 // create and store objectmt:
1382 lua_newtable(L);
1383 luaL_setfuncs(L, json_metatable_functions, 0);
1384 json_regstore(L, objectmt);
1385 // create and store arraymt:
1386 lua_newtable(L);
1387 luaL_setfuncs(L, json_metatable_functions, 0);
1388 json_regstore(L, arraymt);
1389 // create and store ephemeron table to store shadow tables for each JSON object/array
1390 // to allow NULL values returned as nil
1391 lua_newtable(L);
1392 lua_newtable(L); // metatable for ephemeron table
1393 lua_pushliteral(L, "__mode");
1394 lua_pushliteral(L, "k");
1395 lua_rawset(L, -3);
1396 lua_setmetatable(L, -2);
1397 json_regstore(L, shadowtbl);
1398 // set metatable of null marker and make it available through library module:
1399 json_pushnullmark(L);
1400 lua_newtable(L);
1401 luaL_setfuncs(L, json_nullmark_metamethods, 0);
1402 lua_setmetatable(L, -2);
1403 lua_setfield(L, 1, "null");
1404 // return library module (that's expected on top of stack):
1405 return 1;
1406 }