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annotate libraries/json/json.c @ 154:c8669dde9ce2

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Added JSON export function
author jbe
date Thu Jul 31 03:01:53 2014 +0200 (2014-07-31)
parents c8c91216255f
children 185e944182cb
rev   line source
jbe@121 1 #include <lua.h>
jbe@121 2 #include <lauxlib.h>
jbe@122 3 #include <stdlib.h>
jbe@121 4 #include <string.h>
jbe@154 5 #include <math.h>
jbe@121 6
jbe@144 7 // maximum number of nested JSON values (objects and arrays):
jbe@150 8 // NOTE: The Lua reference states that the stack may typically contain at least
jbe@150 9 // "a few thousand elements". Since every nested level consumes
jbe@150 10 // 3 elements on the Lua stack (the object/array, its shadow table,
jbe@150 11 // a string key or a placeholder), we limit the number of nested levels
jbe@150 12 // to 500. If a stack overflow would still happen in the import function,
jbe@150 13 // this is detected nevertheless and an error is thrown (instead of
jbe@150 14 // returning nil and an error string).
jbe@150 15 #define JSON_MAXDEPTH 500
jbe@142 16
jbe@144 17 // macros for usage of Lua registry:
jbe@144 18 #define JSON_REGENT char
jbe@145 19 #define JSON_REGPOINTER void *
jbe@151 20 #define json_pushlightref(L, x) lua_pushlightuserdata((L), &json_reference.x)
jbe@154 21 #define json_islightref(L, i, x) (lua_touserdata((L), (i)) == &json_reference.x)
jbe@145 22 #define json_regpointer(x) (&json_registry.x)
jbe@151 23 #define json_regfetchpointer(L, x) lua_rawgetp((L), LUA_REGISTRYINDEX, (x))
jbe@151 24 #define json_regfetch(L, x) json_regfetchpointer(L, json_regpointer(x))
jbe@151 25 #define json_regstore(L, x) lua_rawsetp(L, LUA_REGISTRYINDEX, json_regpointer(x))
jbe@145 26
jbe@146 27 // generate dummy memory addresses that represent non-modifiable lightuserdata (dummy) objects:
jbe@145 28 static struct {
jbe@146 29 JSON_REGENT nullmark; // magic value to indicate JSON null value in shadow table
jbe@145 30 } json_reference;
jbe@145 31
jbe@144 32 // generate dummy memory addresses that represent Lua objects
jbe@145 33 // via lightuserdata keys and LUA_REGISTRYINDEX:
jbe@144 34 static struct {
jbe@145 35 JSON_REGENT shadowtbl; // ephemeron table that maps tables to their corresponding shadow table
jbe@145 36 JSON_REGENT unknownmt; // metatable for tables that may be either JSON objects or JSON arrays
jbe@145 37 JSON_REGENT objectmt; // metatable for JSON objects
jbe@145 38 JSON_REGENT arraymt; // metatable for JSON arrays
jbe@144 39 } json_registry;
jbe@138 40
jbe@145 41 // marks a Lua table as JSON object or JSON array:
jbe@136 42 // (returns its modified argument or a new table if argument is nil)
jbe@145 43 static int json_mark(lua_State *L, JSON_REGPOINTER mt) {
jbe@145 44 // check if argument is nil
jbe@136 45 if (lua_isnoneornil(L, 1)) {
jbe@145 46 // create new table at stack position 1:
jbe@136 47 lua_settop(L, 0);
jbe@136 48 lua_newtable(L);
jbe@145 49 // create shadow table (leaving previously created table on stack position 1):
jbe@144 50 json_regfetch(L, shadowtbl);
jbe@136 51 lua_pushvalue(L, 1);
jbe@136 52 lua_newtable(L);
jbe@143 53 lua_rawset(L, -3);
jbe@143 54 } else {
jbe@145 55 // push shadow table on top of stack:
jbe@144 56 json_regfetch(L, shadowtbl);
jbe@143 57 lua_pushvalue(L, 1);
jbe@143 58 lua_rawget(L, -2);
jbe@145 59 // if shadow table does not exist:
jbe@143 60 if (lua_isnil(L, -1)) {
jbe@145 61 // create shadow table and leave it on top of stack:
jbe@143 62 lua_newtable(L);
jbe@143 63 lua_pushvalue(L, 1);
jbe@143 64 lua_pushvalue(L, -2);
jbe@143 65 lua_rawset(L, -5);
jbe@143 66 }
jbe@145 67 // move elements from original table to shadow table (that's expected on top of stack):
jbe@143 68 for(lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
jbe@143 69 lua_pushvalue(L, -2);
jbe@143 70 lua_pushnil(L);
jbe@143 71 lua_rawset(L, 1);
jbe@143 72 lua_pushvalue(L, -2);
jbe@143 73 lua_pushvalue(L, -2);
jbe@143 74 lua_rawset(L, -5);
jbe@143 75 }
jbe@136 76 }
jbe@138 77 // discard everything but table to return:
jbe@138 78 lua_settop(L, 1);
jbe@136 79 // set metatable:
jbe@145 80 json_regfetchpointer(L, mt);
jbe@136 81 lua_setmetatable(L, 1);
jbe@138 82 // return table:
jbe@136 83 return 1;
jbe@136 84 }
jbe@136 85
jbe@136 86 // marks a table as JSON object:
jbe@136 87 // (returns its modified argument or a new table if argument is nil)
jbe@136 88 static int json_object(lua_State *L) {
jbe@145 89 return json_mark(L, json_regpointer(objectmt));
jbe@136 90 }
jbe@136 91
jbe@136 92 // marks a table as JSON array:
jbe@136 93 // (returns its modified argument or a new table if argument is nil)
jbe@136 94 static int json_array(lua_State *L) {
jbe@145 95 return json_mark(L, json_regpointer(arraymt));
jbe@136 96 }
jbe@136 97
jbe@145 98 // internal states of JSON parser:
jbe@124 99 #define JSON_STATE_VALUE 0
jbe@124 100 #define JSON_STATE_OBJECT_KEY 1
jbe@124 101 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
jbe@124 102 #define JSON_STATE_OBJECT_VALUE 3
jbe@124 103 #define JSON_STATE_OBJECT_SEPARATOR 4
jbe@124 104 #define JSON_STATE_ARRAY_VALUE 5
jbe@124 105 #define JSON_STATE_ARRAY_SEPARATOR 6
jbe@124 106 #define JSON_STATE_END 7
jbe@121 107
jbe@145 108 // special Lua stack indicies for json_import function:
jbe@138 109 #define json_import_objectmt_idx 2
jbe@138 110 #define json_import_arraymt_idx 3
jbe@138 111 #define json_import_shadowtbl_idx 4
jbe@138 112 #define json_import_nullmark_idx 5
jbe@138 113
jbe@136 114 // decodes a JSON document:
jbe@121 115 static int json_import(lua_State *L) {
jbe@136 116 const char *str; // string to parse
jbe@136 117 size_t total; // total length of string to parse
jbe@136 118 size_t pos = 0; // current position in string to parse
jbe@136 119 size_t level = 0; // nested levels of objects/arrays currently being processed
jbe@145 120 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
jbe@136 121 char c; // variable to store a single character to be processed
jbe@145 122 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
jbe@145 123 char *cbuf; // C buffer to decode JSON string values
jbe@136 124 size_t writepos; // write position of decoded strings in C buffer
jbe@152 125 size_t arraylen; // variable to temporarily store the array length
jbe@147 126 // stack shall contain one function argument:
jbe@138 127 lua_settop(L, 1);
jbe@147 128 // push objectmt onto stack position 2:
jbe@144 129 json_regfetch(L, objectmt);
jbe@147 130 // push arraymt onto stack position 3:
jbe@144 131 json_regfetch(L, arraymt);
jbe@147 132 // push shadowtbl onto stack position 4:
jbe@144 133 json_regfetch(L, shadowtbl);
jbe@147 134 // push nullmark onto stack position 5:
jbe@145 135 json_pushlightref(L, nullmark);
jbe@136 136 // require string as first argument:
jbe@136 137 str = luaL_checklstring(L, 1, &total);
jbe@136 138 // if string contains a NULL byte, this is a syntax error
jbe@136 139 if (strlen(str) != total) goto json_import_syntax_error;
jbe@136 140 // main loop of parser:
jbe@136 141 json_import_loop:
jbe@136 142 // skip whitespace and store next character in variable 'c':
jbe@146 143 while (c = str[pos],
jbe@146 144 c == ' ' ||
jbe@146 145 c == '\f' ||
jbe@146 146 c == '\n' ||
jbe@146 147 c == '\r' ||
jbe@146 148 c == '\t' ||
jbe@146 149 c == '\v'
jbe@146 150 ) pos++;
jbe@136 151 // switch statement to handle certain (single) characters:
jbe@121 152 switch (c) {
jbe@136 153 // handle end of JSON document:
jbe@121 154 case 0:
jbe@136 155 // if end of JSON document was expected, then return top element of stack as result:
jbe@124 156 if (mode == JSON_STATE_END) return 1;
jbe@136 157 // otherwise, the JSON document was malformed:
jbe@121 158 json_import_unexpected_eof:
jbe@121 159 lua_pushnil(L);
jbe@121 160 if (level == 0) lua_pushliteral(L, "Empty string");
jbe@121 161 else lua_pushliteral(L, "Unexpected end of JSON document");
jbe@121 162 return 2;
jbe@136 163 // new JSON object:
jbe@121 164 case '{':
jbe@136 165 // if a JSON object is not expected here, then return an error:
jbe@146 166 if (
jbe@146 167 mode != JSON_STATE_VALUE &&
jbe@146 168 mode != JSON_STATE_OBJECT_VALUE &&
jbe@146 169 mode != JSON_STATE_ARRAY_VALUE
jbe@146 170 ) goto json_import_syntax_error;
jbe@136 171 // create JSON object on stack:
jbe@136 172 lua_newtable(L);
jbe@136 173 // set metatable of JSON object:
jbe@138 174 lua_pushvalue(L, json_import_objectmt_idx);
jbe@125 175 lua_setmetatable(L, -2);
jbe@136 176 // create internal shadow table on stack:
jbe@136 177 lua_newtable(L);
jbe@146 178 // register internal shadow table:
jbe@123 179 lua_pushvalue(L, -2);
jbe@123 180 lua_pushvalue(L, -2);
jbe@138 181 lua_rawset(L, json_import_shadowtbl_idx);
jbe@146 182 // expect object key (or end of object) to follow:
jbe@136 183 mode = JSON_STATE_OBJECT_KEY;
jbe@146 184 // jump to common code for opening JSON object and JSON array:
jbe@142 185 goto json_import_open;
jbe@136 186 // new JSON array:
jbe@121 187 case '[':
jbe@136 188 // if a JSON array is not expected here, then return an error:
jbe@146 189 if (
jbe@146 190 mode != JSON_STATE_VALUE &&
jbe@146 191 mode != JSON_STATE_OBJECT_VALUE &&
jbe@146 192 mode != JSON_STATE_ARRAY_VALUE
jbe@146 193 ) goto json_import_syntax_error;
jbe@136 194 // create JSON array on stack:
jbe@136 195 lua_newtable(L);
jbe@136 196 // set metatable of JSON array:
jbe@138 197 lua_pushvalue(L, json_import_arraymt_idx);
jbe@125 198 lua_setmetatable(L, -2);
jbe@136 199 // create internal shadow table on stack:
jbe@136 200 lua_newtable(L);
jbe@146 201 // register internal shadow table:
jbe@123 202 lua_pushvalue(L, -2);
jbe@123 203 lua_pushvalue(L, -2);
jbe@138 204 lua_rawset(L, json_import_shadowtbl_idx);
jbe@140 205 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
jbe@140 206 lua_pushnil(L);
jbe@146 207 // expect array value (or end of array) to follow:
jbe@142 208 mode = JSON_STATE_ARRAY_VALUE;
jbe@142 209 // continue with common code for opening JSON object and JSON array:
jbe@146 210 // common code for opening JSON object or JSON array:
jbe@142 211 json_import_open:
jbe@142 212 // limit nested levels:
jbe@142 213 if (level >= JSON_MAXDEPTH) {
jbe@142 214 lua_pushnil(L);
jbe@142 215 lua_pushliteral(L, "Too many nested JSON levels");
jbe@142 216 return 2;
jbe@142 217 }
jbe@142 218 // additional buffer overflow protection:
jbe@142 219 if (!lua_checkstack(L, LUA_MINSTACK))
jbe@142 220 return luaL_error(L, "Caught stack overflow in JSON import function (too many nested levels and stack size too small)");
jbe@136 221 // increment level:
jbe@121 222 level++;
jbe@142 223 // consume input character:
jbe@142 224 pos++;
jbe@121 225 goto json_import_loop;
jbe@136 226 // end of JSON object:
jbe@121 227 case '}':
jbe@136 228 // if end of JSON object is not expected here, then return an error:
jbe@146 229 if (
jbe@146 230 mode != JSON_STATE_OBJECT_KEY &&
jbe@146 231 mode != JSON_STATE_OBJECT_SEPARATOR
jbe@146 232 ) goto json_import_syntax_error;
jbe@136 233 // jump to common code for end of JSON object and JSON array:
jbe@121 234 goto json_import_close;
jbe@136 235 // end of JSON array:
jbe@121 236 case ']':
jbe@136 237 // if end of JSON array is not expected here, then return an error:
jbe@146 238 if (
jbe@146 239 mode != JSON_STATE_ARRAY_VALUE &&
jbe@146 240 mode != JSON_STATE_ARRAY_SEPARATOR
jbe@146 241 ) goto json_import_syntax_error;
jbe@146 242 // pop nil key/magic (that was needed to keep stack balance):
jbe@140 243 lua_pop(L, 1);
jbe@136 244 // continue with common code for end of JSON object and JSON array:
jbe@136 245 // common code for end of JSON object or JSON array:
jbe@121 246 json_import_close:
jbe@136 247 // consume input character:
jbe@121 248 pos++;
jbe@136 249 // pop shadow table:
jbe@136 250 lua_pop(L, 1);
jbe@136 251 // check if nested:
jbe@121 252 if (--level) {
jbe@146 253 // if nested,
jbe@146 254 // check if outer(!) structure is an array or object:
jbe@140 255 if (lua_isnil(L, -2)) {
jbe@136 256 // select array value processing:
jbe@124 257 mode = JSON_STATE_ARRAY_VALUE;
jbe@121 258 } else {
jbe@136 259 // select object value processing:
jbe@124 260 mode = JSON_STATE_OBJECT_VALUE;
jbe@121 261 }
jbe@136 262 // store value in outer structure:
jbe@121 263 goto json_import_process_value;
jbe@121 264 }
jbe@136 265 // if not nested, then expect end of JSON document and continue with loop:
jbe@136 266 mode = JSON_STATE_END;
jbe@121 267 goto json_import_loop;
jbe@136 268 // key terminator:
jbe@121 269 case ':':
jbe@136 270 // if key terminator is not expected here, then return an error:
jbe@124 271 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
jbe@121 272 goto json_import_syntax_error;
jbe@136 273 // consume input character:
jbe@121 274 pos++;
jbe@146 275 // expect object value to follow:
jbe@124 276 mode = JSON_STATE_OBJECT_VALUE;
jbe@146 277 // continue with loop:
jbe@121 278 goto json_import_loop;
jbe@136 279 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
jbe@121 280 case ',':
jbe@146 281 // branch according to parser state:
jbe@124 282 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
jbe@146 283 // expect an object key to follow:
jbe@124 284 mode = JSON_STATE_OBJECT_KEY;
jbe@124 285 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
jbe@146 286 // expect an array value to follow:
jbe@124 287 mode = JSON_STATE_ARRAY_VALUE;
jbe@121 288 } else {
jbe@136 289 // if value terminator is not expected here, then return an error:
jbe@136 290 goto json_import_syntax_error;
jbe@121 291 }
jbe@136 292 // consume input character:
jbe@121 293 pos++;
jbe@136 294 // continue with loop:
jbe@121 295 goto json_import_loop;
jbe@136 296 // string literal:
jbe@121 297 case '"':
jbe@146 298 // consume quote character:
jbe@146 299 pos++;
jbe@136 300 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
jbe@121 301 cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
jbe@121 302 writepos = 0;
jbe@146 303 // loop through the characters until encountering end quote:
jbe@121 304 while ((c = str[pos++]) != '"') {
jbe@121 305 if (c == 0) {
jbe@146 306 // handle unexpected end of JSON document:
jbe@121 307 goto json_import_unexpected_eof;
jbe@121 308 } else if (c < 32 || c == 127) {
jbe@136 309 // do not allow ASCII control characters:
jbe@136 310 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
jbe@136 311 // by this parser to allow different encodings than Unicode
jbe@121 312 lua_pushnil(L);
jbe@121 313 lua_pushliteral(L, "Unexpected control character in JSON string");
jbe@121 314 return 2;
jbe@121 315 } else if (c == '\\') {
jbe@136 316 // read next char after backslash escape:
jbe@121 317 c = str[pos++];
jbe@121 318 switch (c) {
jbe@136 319 // unexpected end-of-string:
jbe@121 320 case 0:
jbe@121 321 goto json_import_unexpected_eof;
jbe@136 322 // unescaping of quotation mark, slash, and backslash:
jbe@121 323 case '"':
jbe@121 324 case '/':
jbe@121 325 case '\\':
jbe@121 326 cbuf[writepos++] = c;
jbe@121 327 break;
jbe@136 328 // unescaping of backspace:
jbe@146 329 case 'b': cbuf[writepos++] = '\b'; break;
jbe@136 330 // unescaping of form-feed:
jbe@146 331 case 'f': cbuf[writepos++] = '\f'; break;
jbe@136 332 // unescaping of new-line:
jbe@146 333 case 'n': cbuf[writepos++] = '\n'; break;
jbe@136 334 // unescaping of carriage-return:
jbe@146 335 case 'r': cbuf[writepos++] = '\r'; break;
jbe@136 336 // unescaping of tabulator:
jbe@146 337 case 't': cbuf[writepos++] = '\t'; break;
jbe@136 338 // unescaping of UTF-16 characters
jbe@121 339 case 'u':
jbe@121 340 lua_pushnil(L);
jbe@121 341 lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet"); // TODO
jbe@121 342 return 2;
jbe@136 343 // unexpected escape sequence:
jbe@121 344 default:
jbe@121 345 lua_pushnil(L);
jbe@121 346 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
jbe@121 347 return 2;
jbe@121 348 }
jbe@121 349 } else {
jbe@136 350 // normal character:
jbe@121 351 cbuf[writepos++] = c;
jbe@121 352 }
jbe@121 353 }
jbe@136 354 // process buffer to Lua string:
jbe@121 355 luaL_pushresultsize(&luabuf, writepos);
jbe@136 356 // continue with processing of decoded string:
jbe@121 357 goto json_import_process_value;
jbe@121 358 }
jbe@136 359 // process values whose type is is not deducible from a single character:
jbe@136 360 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
jbe@146 361 // for numbers,
jbe@146 362 // use strtod() call to parse a (double precision) floating point number:
jbe@122 363 char *endptr;
jbe@122 364 double numval;
jbe@122 365 numval = strtod(str+pos, &endptr);
jbe@146 366 // catch parsing errors:
jbe@122 367 if (endptr == str+pos) goto json_import_syntax_error;
jbe@146 368 // consume characters that were parsed:
jbe@122 369 pos += endptr - (str+pos);
jbe@146 370 // push parsed (double precision) floating point number on Lua stack:
jbe@122 371 lua_pushnumber(L, numval);
jbe@122 372 } else if (!strncmp(str+pos, "true", 4)) {
jbe@136 373 // consume 4 input characters for "true":
jbe@121 374 pos += 4;
jbe@147 375 // put Lua true value onto stack:
jbe@136 376 lua_pushboolean(L, 1);
jbe@121 377 } else if (!strncmp(str+pos, "false", 5)) {
jbe@136 378 // consume 5 input characters for "false":
jbe@121 379 pos += 5;
jbe@147 380 // put Lua false value onto stack:
jbe@136 381 lua_pushboolean(L, 0);
jbe@121 382 } else if (!strncmp(str+pos, "null", 4)) {
jbe@136 383 // consume 4 input characters for "null":
jbe@136 384 pos += 4;
jbe@153 385 // different behavor for top-level and sub-levels:
jbe@153 386 if (level) {
jbe@153 387 // if sub-level,
jbe@153 388 // push special null-marker onto stack:
jbe@153 389 lua_pushvalue(L, json_import_nullmark_idx);
jbe@153 390 } else {
jbe@153 391 // if top-level,
jbe@153 392 // push nil onto stack:
jbe@153 393 lua_pushnil(L);
jbe@153 394 }
jbe@121 395 } else {
jbe@136 396 // all other cases are a syntax error:
jbe@121 397 goto json_import_syntax_error;
jbe@121 398 }
jbe@136 399 // process a decoded value or key value pair (expected on top of Lua stack):
jbe@136 400 json_import_process_value:
jbe@121 401 switch (mode) {
jbe@136 402 // an object key has been read:
jbe@124 403 case JSON_STATE_OBJECT_KEY:
jbe@136 404 // if an object key is not a string, then this is a syntax error:
jbe@121 405 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
jbe@146 406 // expect key terminator to follow:
jbe@124 407 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
jbe@146 408 // continue with loop:
jbe@121 409 goto json_import_loop;
jbe@136 410 // a key value pair has been read:
jbe@124 411 case JSON_STATE_OBJECT_VALUE:
jbe@136 412 // store key value pair in outer shadow table:
jbe@130 413 lua_rawset(L, -3);
jbe@146 414 // expect value terminator (or end of object) to follow:
jbe@124 415 mode = JSON_STATE_OBJECT_SEPARATOR;
jbe@146 416 // continue with loop:
jbe@121 417 goto json_import_loop;
jbe@136 418 // an array value has been read:
jbe@124 419 case JSON_STATE_ARRAY_VALUE:
jbe@152 420 // get current array length:
jbe@152 421 arraylen = lua_rawlen(L, -3);
jbe@152 422 // throw error if array would exceed INT_MAX elements:
jbe@152 423 // TODO: Lua 5.3 may support more elements
jbe@152 424 if (arraylen >= INT_MAX) {
jbe@152 425 lua_pushnil(L);
jbe@152 426 lua_pushfstring(L, "Array exceeded length of %d elements", INT_MAX);
jbe@152 427 }
jbe@136 428 // store value in outer shadow table:
jbe@152 429 lua_rawseti(L, -3, arraylen + 1);
jbe@146 430 // expect value terminator (or end of object) to follow:
jbe@124 431 mode = JSON_STATE_ARRAY_SEPARATOR;
jbe@146 432 // continue with loop
jbe@121 433 goto json_import_loop;
jbe@136 434 // a single value has been read:
jbe@124 435 case JSON_STATE_VALUE:
jbe@136 436 // leave value on top of stack, expect end of JSON document, and continue with loop:
jbe@124 437 mode = JSON_STATE_END;
jbe@121 438 goto json_import_loop;
jbe@121 439 }
jbe@146 440 // syntax error handling (reachable by goto statement):
jbe@136 441 json_import_syntax_error:
jbe@121 442 lua_pushnil(L);
jbe@121 443 lua_pushliteral(L, "Syntax error in JSON document");
jbe@121 444 return 2;
jbe@121 445 }
jbe@121 446
jbe@146 447 // special Lua stack indicies for json_path function:
jbe@138 448 #define json_path_shadowtbl_idx 1
jbe@138 449 #define json_path_nullmark_idx 2
jbe@146 450
jbe@146 451 // stack offset of arguments to json_path function:
jbe@138 452 #define json_path_idxshift 2
jbe@138 453
jbe@146 454 // gets a value or its type from a JSON document (passed as first argument)
jbe@147 455 // using a path (passed as variable number of keys after first argument):
jbe@137 456 static int json_path(lua_State *L, int type_mode) {
jbe@146 457 int stacktop; // stack index of top of stack (after shifting)
jbe@146 458 int idx = 2 + json_path_idxshift; // stack index of current argument to process
jbe@148 459 // insert shadowtbl into stack at position 1 (shifting the arguments):
jbe@144 460 json_regfetch(L, shadowtbl);
jbe@138 461 lua_insert(L, 1);
jbe@148 462 // insert nullmark into stack at position 2 (shifting the arguments):
jbe@145 463 json_pushlightref(L, nullmark);
jbe@138 464 lua_insert(L, 2);
jbe@146 465 // store stack index of top of stack:
jbe@138 466 stacktop = lua_gettop(L);
jbe@146 467 // use first argument as "current value" (stored on top of stack):
jbe@138 468 lua_pushvalue(L, 1 + json_path_idxshift);
jbe@146 469 // process each "path key" (2nd argument and following arguments):
jbe@138 470 while (idx <= stacktop) {
jbe@146 471 // if "current value" (on top of stack) is nil, then the path cannot be walked and nil is returned:
jbe@137 472 if (lua_isnil(L, -1)) return 1;
jbe@137 473 // try to get shadow table of "current value":
jbe@130 474 lua_pushvalue(L, -1);
jbe@138 475 lua_rawget(L, json_path_shadowtbl_idx);
jbe@126 476 if (lua_isnil(L, -1)) {
jbe@137 477 // if no shadow table is found,
jbe@130 478 if (lua_type(L, -1) == LUA_TTABLE) {
jbe@146 479 // and if "current value" is a table,
jbe@146 480 // drop nil from stack:
jbe@146 481 lua_pop(L, 1);
jbe@137 482 // get "next value" using the "path key":
jbe@130 483 lua_pushvalue(L, idx++);
jbe@130 484 lua_gettable(L, -2);
jbe@130 485 } else {
jbe@137 486 // if "current value" is not a table,
jbe@146 487 // then the path cannot be walked and nil (already on top of stack) is returned:
jbe@137 488 return 1;
jbe@130 489 }
jbe@130 490 } else {
jbe@137 491 // if a shadow table is found,
jbe@137 492 // set "current value" to its shadow table:
jbe@130 493 lua_replace(L, -2);
jbe@137 494 // get "next value" using the "path key":
jbe@130 495 lua_pushvalue(L, idx++);
jbe@130 496 lua_rawget(L, -2);
jbe@126 497 }
jbe@137 498 // the "next value" replaces the "current value":
jbe@130 499 lua_replace(L, -2);
jbe@126 500 }
jbe@137 501 if (!type_mode) {
jbe@137 502 // if a value (and not its type) was requested,
jbe@137 503 // check if value is the null-marker, and store nil on top of Lua stack in that case:
jbe@138 504 if (lua_rawequal(L, -1, json_path_nullmark_idx)) lua_pushnil(L);
jbe@137 505 } else {
jbe@137 506 // if the type was requested,
jbe@137 507 // check if value is the null-marker:
jbe@138 508 if (lua_rawequal(L, -1, json_path_nullmark_idx)) {
jbe@137 509 // if yes, store string "null" on top of Lua stack:
jbe@130 510 lua_pushliteral(L, "null");
jbe@137 511 } else {
jbe@137 512 // otherwise,
jbe@138 513 // check if metatable indicates "object" or "array":
jbe@138 514 if (lua_getmetatable(L, -1)) {
jbe@144 515 json_regfetch(L, objectmt);
jbe@138 516 if (lua_rawequal(L, -2, -1)) {
jbe@146 517 // if value has metatable for JSON objects,
jbe@138 518 // return string "object":
jbe@138 519 lua_pushliteral(L, "object");
jbe@138 520 return 1;
jbe@138 521 }
jbe@144 522 json_regfetch(L, arraymt);
jbe@138 523 if (lua_rawequal(L, -3, -1)) {
jbe@146 524 // if value has metatable for JSON arrays,
jbe@146 525 // return string "object":
jbe@138 526 lua_pushliteral(L, "array");
jbe@138 527 return 1;
jbe@138 528 }
jbe@146 529 // remove 3 metatables (one of the value, two for comparison) from stack:
jbe@138 530 lua_pop(L, 3);
jbe@138 531 }
jbe@138 532 // otherwise, get the Lua type:
jbe@138 533 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
jbe@126 534 }
jbe@126 535 }
jbe@137 536 // return the top most value on the Lua stack:
jbe@137 537 return 1;
jbe@130 538 }
jbe@130 539
jbe@147 540 // gets a value from a JSON document (passed as first argument)
jbe@147 541 // using a path (passed as variable number of keys after first argument):
jbe@130 542 static int json_get(lua_State *L) {
jbe@137 543 return json_path(L, 0);
jbe@130 544 }
jbe@130 545
jbe@147 546 // gets a value's type from a JSON document (passed as first argument)
jbe@147 547 // using a path (variable number of keys after first argument):
jbe@130 548 static int json_type(lua_State *L) {
jbe@137 549 return json_path(L, 1);
jbe@130 550 }
jbe@130 551
jbe@147 552 // checks if a value in a JSON document (first argument) is
jbe@147 553 // explicitly set to null:
jbe@130 554 static int json_isnull(lua_State *L) {
jbe@137 555 const char *jsontype;
jbe@147 556 // call json_type function with variable arguments:
jbe@138 557 lua_pushcfunction(L, json_type);
jbe@137 558 lua_insert(L, 1);
jbe@137 559 lua_call(L, lua_gettop(L) - 1, 1);
jbe@147 560 // return true if result equals to string "null", otherwise return false:
jbe@137 561 jsontype = lua_tostring(L, -1);
jbe@137 562 if (jsontype && !strcmp(jsontype, "null")) lua_pushboolean(L, 1);
jbe@137 563 else lua_pushboolean(L, 0);
jbe@137 564 return 1;
jbe@130 565 }
jbe@130 566
jbe@146 567 // special Lua stack indicies for json_setnull function:
jbe@138 568 #define json_setnull_unknownmt_idx 3
jbe@138 569 #define json_setnull_objectmt_idx 4
jbe@138 570 #define json_setnull_arraymt_idx 5
jbe@138 571 #define json_setnull_shadowtbl_idx 6
jbe@138 572
jbe@147 573 // sets a value in a JSON object or JSON array explicitly to null:
jbe@147 574 // NOTE: JSON null is different than absence of a key
jbe@131 575 static int json_setnull(lua_State *L) {
jbe@147 576 // stack shall contain two function arguments:
jbe@131 577 lua_settop(L, 2);
jbe@148 578 // push unknownmt onto stack position 3:
jbe@144 579 json_regfetch(L, unknownmt);
jbe@148 580 // push objectmt onto stack position 4:
jbe@144 581 json_regfetch(L, objectmt);
jbe@148 582 // push arraymt onto stack position 5:
jbe@144 583 json_regfetch(L, arraymt);
jbe@148 584 // push shadowtbl onto stack position 6:
jbe@144 585 json_regfetch(L, shadowtbl);
jbe@147 586 // set metatable if necessary (leaves unknown number of elements on stack):
jbe@138 587 if (
jbe@147 588 !lua_getmetatable(L, 1) || (
jbe@147 589 !lua_rawequal(L, -1, json_setnull_unknownmt_idx) &&
jbe@147 590 !lua_rawequal(L, -1, json_setnull_objectmt_idx) &&
jbe@147 591 !lua_rawequal(L, -1, json_setnull_arraymt_idx)
jbe@147 592 )
jbe@138 593 ) {
jbe@138 594 lua_pushvalue(L, json_setnull_unknownmt_idx);
jbe@138 595 lua_setmetatable(L, 1);
jbe@138 596 }
jbe@147 597 // try to get shadow table:
jbe@131 598 lua_pushvalue(L, 1);
jbe@138 599 lua_rawget(L, json_setnull_shadowtbl_idx);
jbe@131 600 if (lua_isnil(L, -1)) {
jbe@147 601 // if no shadow table is found,
jbe@147 602 // create new shadow table (and leave it on top of stack):
jbe@131 603 lua_newtable(L);
jbe@147 604 // register shadow table:
jbe@131 605 lua_pushvalue(L, 1);
jbe@131 606 lua_pushvalue(L, -2);
jbe@138 607 lua_rawset(L, json_setnull_shadowtbl_idx);
jbe@131 608 }
jbe@147 609 // push key (second argument) and null-marker after shadow table onto stack:
jbe@131 610 lua_pushvalue(L, 2);
jbe@145 611 json_pushlightref(L, nullmark);
jbe@147 612 // store key and null-marker in shadow table:
jbe@131 613 lua_rawset(L, -3);
jbe@147 614 // return nothing:
jbe@131 615 return 0;
jbe@131 616 }
jbe@131 617
jbe@147 618 // returns the length of a JSON array (or zero for a table without numeric keys):
jbe@130 619 static int json_len(lua_State *L) {
jbe@147 620 // stack shall contain one function argument:
jbe@130 621 lua_settop(L, 1);
jbe@148 622 // try to get corresponding shadow table for first argument:
jbe@144 623 json_regfetch(L, shadowtbl);
jbe@130 624 lua_pushvalue(L, 1);
jbe@138 625 lua_rawget(L, -2);
jbe@147 626 // if shadow table does not exist, return length of argument, else length of shadow table:
jbe@147 627 lua_pushnumber(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
jbe@123 628 return 1;
jbe@123 629 }
jbe@123 630
jbe@146 631 // special Lua stack indicies for json_index function:
jbe@141 632 #define json_index_nullmark_idx 3
jbe@141 633 #define json_index_shadowtbl_idx 4
jbe@141 634
jbe@130 635 static int json_index(lua_State *L) {
jbe@148 636 // stack shall contain two function arguments:
jbe@130 637 lua_settop(L, 2);
jbe@148 638 // push nullmark onto stack position 3:
jbe@148 639 json_pushlightref(L, nullmark);
jbe@148 640 // push shadowtbl onto stack position 4:
jbe@144 641 json_regfetch(L, shadowtbl);
jbe@148 642 // get corresponding shadow table for first argument:
jbe@130 643 lua_pushvalue(L, 1);
jbe@141 644 lua_rawget(L, json_index_shadowtbl_idx);
jbe@148 645 // throw error if no shadow table was found:
jbe@139 646 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@148 647 // use key passed as second argument to lookup value in shadow table:
jbe@130 648 lua_pushvalue(L, 2);
jbe@130 649 lua_rawget(L, -2);
jbe@148 650 // if value is null-marker, then push nil onto stack:
jbe@141 651 if (lua_rawequal(L, -1, json_index_nullmark_idx)) lua_pushnil(L);
jbe@148 652 // return either looked up value, or nil
jbe@127 653 return 1;
jbe@127 654 }
jbe@127 655
jbe@130 656 static int json_newindex(lua_State *L) {
jbe@148 657 // stack shall contain three function arguments:
jbe@130 658 lua_settop(L, 3);
jbe@148 659 // get corresponding shadow table for first argument:
jbe@144 660 json_regfetch(L, shadowtbl);
jbe@123 661 lua_pushvalue(L, 1);
jbe@143 662 lua_rawget(L, -2);
jbe@148 663 // throw error if no shadow table was found:
jbe@130 664 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@148 665 // replace first argument with shadow table:
jbe@130 666 lua_replace(L, 1);
jbe@148 667 // reset stack and use second and third argument to write to shadow table:
jbe@139 668 lua_settop(L, 3);
jbe@130 669 lua_rawset(L, 1);
jbe@148 670 // return nothing:
jbe@148 671 return 0;
jbe@121 672 }
jbe@121 673
jbe@146 674 // special Lua stack indicies for json_pairs_iterfunc function:
jbe@139 675 #define json_pairs_iterfunc_nullmark_idx 3
jbe@139 676 #define json_pairs_iterfunc_shadowtbl_idx 4
jbe@139 677
jbe@135 678 static int json_pairs_iterfunc(lua_State *L) {
jbe@149 679 // stack shall contain two function arguments:
jbe@135 680 lua_settop(L, 2);
jbe@149 681 // push nullmark onto stack position 3:
jbe@149 682 json_pushlightref(L, nullmark);
jbe@149 683 // push shadowtbl onto stack position 4:
jbe@144 684 json_regfetch(L, shadowtbl);
jbe@149 685 // get corresponding shadow table for first argument:
jbe@135 686 lua_pushvalue(L, 1);
jbe@139 687 lua_rawget(L, json_pairs_iterfunc_shadowtbl_idx);
jbe@149 688 // throw error if no shadow table was found:
jbe@135 689 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@149 690 // get next key value pair from shadow table (using previous key from argument 2)
jbe@149 691 // and return nothing if there is no next pair:
jbe@135 692 lua_pushvalue(L, 2);
jbe@135 693 if (!lua_next(L, -2)) return 0;
jbe@149 694 // replace null-marker with nil:
jbe@139 695 if (lua_rawequal(L, -1, json_pairs_iterfunc_nullmark_idx)) {
jbe@135 696 lua_pop(L, 1);
jbe@135 697 lua_pushnil(L);
jbe@135 698 }
jbe@149 699 // return key and value (or key and nil, if null-marker was found):
jbe@135 700 return 2;
jbe@135 701 }
jbe@135 702
jbe@149 703 // returns a triple such that 'for key, value in pairs(obj) do ... end'
jbe@149 704 // iterates through all key value pairs (including JSON null keys represented as Lua nil):
jbe@135 705 static int json_pairs(lua_State *L) {
jbe@149 706 // return triple of function json_pairs_iterfunc, first argument, and nil:
jbe@139 707 lua_pushcfunction(L, json_pairs_iterfunc);
jbe@135 708 lua_pushvalue(L, 1);
jbe@135 709 lua_pushnil(L);
jbe@135 710 return 3;
jbe@135 711 }
jbe@135 712
jbe@146 713 // special Lua stack indicies for json_ipairs_iterfunc function:
jbe@139 714 #define json_ipairs_iterfunc_nullmark_idx 3
jbe@139 715 #define json_ipairs_iterfunc_shadowtbl_idx 4
jbe@139 716
jbe@134 717 static int json_ipairs_iterfunc(lua_State *L) {
jbe@152 718 lua_Integer idx;
jbe@149 719 // stack shall contain two function arguments:
jbe@134 720 lua_settop(L, 2);
jbe@149 721 // push nullmark onto stack position 3:
jbe@149 722 json_pushlightref(L, nullmark);
jbe@149 723 // push shadowtbl onto stack position 4:
jbe@144 724 json_regfetch(L, shadowtbl);
jbe@149 725 // calculate new index by incrementing second argument:
jbe@134 726 idx = lua_tointeger(L, 2) + 1;
jbe@149 727 // get corresponding shadow table for first argument:
jbe@134 728 lua_pushvalue(L, 1);
jbe@139 729 lua_rawget(L, json_ipairs_iterfunc_shadowtbl_idx);
jbe@149 730 // throw error if no shadow table was found:
jbe@134 731 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@149 732 // do integer lookup in shadow table:
jbe@134 733 lua_rawgeti(L, -1, idx);
jbe@149 734 // return nothing if there was no value:
jbe@134 735 if (lua_isnil(L, -1)) return 0;
jbe@149 736 // return new index and
jbe@149 737 // either the looked up value if it is not equal to the null-marker
jbe@149 738 // or nil instead of null-marker:
jbe@134 739 lua_pushinteger(L, idx);
jbe@139 740 if (lua_rawequal(L, -2, json_ipairs_iterfunc_nullmark_idx)) lua_pushnil(L);
jbe@134 741 else lua_pushvalue(L, -2);
jbe@134 742 return 2;
jbe@134 743 }
jbe@134 744
jbe@149 745 // returns a triple such that 'for idx, value in ipairs(ary) do ... end'
jbe@149 746 // iterates through all values (including JSON null represented as Lua nil):
jbe@134 747 static int json_ipairs(lua_State *L) {
jbe@149 748 // return triple of function json_ipairs_iterfunc, first argument, and zero:
jbe@139 749 lua_pushcfunction(L, json_ipairs_iterfunc);
jbe@134 750 lua_pushvalue(L, 1);
jbe@134 751 lua_pushinteger(L, 0);
jbe@134 752 return 3;
jbe@134 753 }
jbe@134 754
jbe@154 755 #define JSON_TABLETYPE_UNKNOWN 0
jbe@154 756 #define JSON_TABLETYPE_OBJECT 1
jbe@154 757 #define JSON_TABLETYPE_ARRAY 2
jbe@154 758
jbe@154 759 static int json_export(lua_State *L) {
jbe@154 760 lua_Number num;
jbe@154 761 const char *str;
jbe@154 762 unsigned char c;
jbe@154 763 size_t strlen;
jbe@154 764 size_t pos = 0;
jbe@154 765 luaL_Buffer buf;
jbe@154 766 char hexcode[7]; // backslash, character 'u', 4 hex digits, and terminating NULL byte
jbe@154 767 int luatype;
jbe@154 768 int tabletype = JSON_TABLETYPE_UNKNOWN;
jbe@154 769 int needsep = 0;
jbe@154 770 lua_Integer idx;
jbe@154 771 lua_settop(L, 1);
jbe@154 772 switch (lua_type(L, 1)) {
jbe@154 773 case LUA_TNIL:
jbe@154 774 lua_pushliteral(L, "null");
jbe@154 775 return 1;
jbe@154 776 case LUA_TNUMBER:
jbe@154 777 num = lua_tonumber(L, 1);
jbe@154 778 if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
jbe@154 779 if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
jbe@154 780 lua_tostring(L, 1);
jbe@154 781 return 1;
jbe@154 782 case LUA_TBOOLEAN:
jbe@154 783 if (lua_toboolean(L, 1)) lua_pushliteral(L, "true");
jbe@154 784 else lua_pushliteral(L, "false");
jbe@154 785 return 1;
jbe@154 786 case LUA_TSTRING:
jbe@154 787 str = lua_tolstring(L, 1, &strlen);
jbe@154 788 luaL_buffinit(L, &buf);
jbe@154 789 luaL_addchar(&buf, '"');
jbe@154 790 while (pos < strlen) {
jbe@154 791 c = str[pos++];
jbe@154 792 if (c == '"') luaL_addstring(&buf, "\\\"");
jbe@154 793 else if (c == '\\') luaL_addstring(&buf, "\\\\");
jbe@154 794 else if (c == 127) luaL_addstring(&buf, "\\u007F");
jbe@154 795 else if (c >= 32) luaL_addchar(&buf, c);
jbe@154 796 else if (c == '\b') luaL_addstring(&buf, "\\b");
jbe@154 797 else if (c == '\f') luaL_addstring(&buf, "\\f");
jbe@154 798 else if (c == '\n') luaL_addstring(&buf, "\\n");
jbe@154 799 else if (c == '\r') luaL_addstring(&buf, "\\r");
jbe@154 800 else if (c == '\t') luaL_addstring(&buf, "\\t");
jbe@154 801 else if (c == '\v') luaL_addstring(&buf, "\\v");
jbe@154 802 else {
jbe@154 803 sprintf(hexcode, "\\u%04X", c);
jbe@154 804 luaL_addstring(&buf, hexcode);
jbe@154 805 }
jbe@154 806 }
jbe@154 807 luaL_addchar(&buf, '"');
jbe@154 808 luaL_pushresult(&buf);
jbe@154 809 return 1;
jbe@154 810 case LUA_TTABLE:
jbe@154 811 if (lua_getmetatable(L, 1)) {
jbe@154 812 json_regfetch(L, objectmt);
jbe@154 813 if (lua_rawequal(L, -2, -1)) {
jbe@154 814 tabletype = JSON_TABLETYPE_OBJECT;
jbe@154 815 } else {
jbe@154 816 json_regfetch(L, arraymt);
jbe@154 817 if (lua_rawequal(L, -3, -1)) tabletype = JSON_TABLETYPE_ARRAY;
jbe@154 818 }
jbe@154 819 }
jbe@154 820 json_regfetch(L, shadowtbl);
jbe@154 821 lua_pushvalue(L, 1);
jbe@154 822 lua_rawget(L, -2);
jbe@154 823 if (!lua_isnil(L, -1)) lua_replace(L, 1);
jbe@154 824 lua_settop(L, 1);
jbe@154 825 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
jbe@154 826 for (lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
jbe@154 827 luatype = lua_type(L, -2);
jbe@154 828 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
jbe@154 829 if (luatype == LUA_TSTRING) tabletype = JSON_TABLETYPE_OBJECT;
jbe@154 830 else if (luatype == LUA_TNUMBER) tabletype = JSON_TABLETYPE_ARRAY;
jbe@154 831 } else if (
jbe@154 832 (tabletype == JSON_TABLETYPE_OBJECT && luatype == LUA_TNUMBER) ||
jbe@154 833 (tabletype == JSON_TABLETYPE_ARRAY && luatype == LUA_TSTRING)
jbe@154 834 ) {
jbe@154 835 goto json_export_tabletype_error;
jbe@154 836 }
jbe@154 837 }
jbe@154 838 }
jbe@154 839 switch (tabletype) {
jbe@154 840 case JSON_TABLETYPE_OBJECT:
jbe@154 841 lua_settop(L, 3);
jbe@154 842 luaL_buffinit(L, &buf);
jbe@154 843 luaL_addchar(&buf, '{');
jbe@154 844 for (lua_pushnil(L); lua_next(L, 1); ) {
jbe@154 845 if (lua_type(L, -2) == LUA_TSTRING) {
jbe@154 846 lua_replace(L, 3);
jbe@154 847 lua_replace(L, 2);
jbe@154 848 if (needsep) luaL_addchar(&buf, ',');
jbe@154 849 else needsep = 1;
jbe@154 850 lua_pushcfunction(L, json_export);
jbe@154 851 lua_pushvalue(L, 2);
jbe@154 852 lua_call(L, 1, 1);
jbe@154 853 luaL_addvalue(&buf);
jbe@154 854 luaL_addchar(&buf, ':');
jbe@154 855 if (json_islightref(L, 3, nullmark)) {
jbe@154 856 luaL_addstring(&buf, "null");
jbe@154 857 } else {
jbe@154 858 lua_pushcfunction(L, json_export);
jbe@154 859 lua_pushvalue(L, 3);
jbe@154 860 lua_call(L, 1, 1);
jbe@154 861 luaL_addvalue(&buf);
jbe@154 862 }
jbe@154 863 lua_pushvalue(L, 2);
jbe@154 864 } else {
jbe@154 865 lua_pop(L, 1);
jbe@154 866 }
jbe@154 867 }
jbe@154 868 luaL_addchar(&buf, '}');
jbe@154 869 luaL_pushresult(&buf);
jbe@154 870 return 1;
jbe@154 871 case JSON_TABLETYPE_ARRAY:
jbe@154 872 lua_settop(L, 2);
jbe@154 873 luaL_buffinit(L, &buf);
jbe@154 874 luaL_addchar(&buf, '[');
jbe@154 875 for (idx = 1; ; idx++) {
jbe@154 876 lua_rawgeti(L, 1, idx);
jbe@154 877 if (lua_isnil(L, -1)) {
jbe@154 878 lua_pop(L, 1);
jbe@154 879 break;
jbe@154 880 }
jbe@154 881 lua_replace(L, 2);
jbe@154 882 if (needsep) luaL_addchar(&buf, ',');
jbe@154 883 else needsep = 1;
jbe@154 884 lua_pushcfunction(L, json_export);
jbe@154 885 lua_pushvalue(L, 2);
jbe@154 886 lua_call(L, 1, 1);
jbe@154 887 luaL_addvalue(&buf);
jbe@154 888 }
jbe@154 889 luaL_addchar(&buf, ']');
jbe@154 890 luaL_pushresult(&buf);
jbe@154 891 return 1;
jbe@154 892 }
jbe@154 893 json_export_tabletype_error:
jbe@154 894 return luaL_error(L, "JSON export not possible for ambiguous table (cannot decide whether it is an object or array)");
jbe@154 895 }
jbe@154 896 return luaL_error(L, "JSON export not possible for values of type \"%s\"", lua_typename(L, lua_type(L, 1)));
jbe@154 897 }
jbe@154 898
jbe@149 899 // functions in library module:
jbe@121 900 static const struct luaL_Reg json_module_functions[] = {
jbe@133 901 {"object", json_object},
jbe@133 902 {"array", json_array},
jbe@121 903 {"import", json_import},
jbe@154 904 {"export", json_export},
jbe@130 905 {"get", json_get},
jbe@127 906 {"type", json_type},
jbe@123 907 {"isnull", json_isnull},
jbe@131 908 {"setnull", json_setnull},
jbe@121 909 {NULL, NULL}
jbe@121 910 };
jbe@121 911
jbe@149 912 // metamethods for JSON objects, JSON arrays, and unknown JSON collections (object or array):
jbe@126 913 static const struct luaL_Reg json_metatable_functions[] = {
jbe@130 914 {"__len", json_len},
jbe@130 915 {"__index", json_index},
jbe@130 916 {"__newindex", json_newindex},
jbe@135 917 {"__pairs", json_pairs},
jbe@134 918 {"__ipairs", json_ipairs},
jbe@126 919 {NULL, NULL}
jbe@126 920 };
jbe@126 921
jbe@149 922 // initializes json library:
jbe@121 923 int luaopen_json(lua_State *L) {
jbe@149 924 // empty stack:
jbe@126 925 lua_settop(L, 0);
jbe@149 926 // push library module onto stack position 1:
jbe@149 927 lua_newtable(L);
jbe@149 928 // register library functions:
jbe@149 929 luaL_setfuncs(L, json_module_functions, 0);
jbe@149 930 // create and store unknownmt:
jbe@138 931 lua_newtable(L);
jbe@138 932 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 933 json_regstore(L, unknownmt);
jbe@149 934 // create and store objectmt:
jbe@138 935 lua_newtable(L);
jbe@138 936 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 937 json_regstore(L, objectmt);
jbe@149 938 // create and store arraymt:
jbe@138 939 lua_newtable(L);
jbe@138 940 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 941 json_regstore(L, arraymt);
jbe@149 942 // create and store ephemeron table to store shadow tables for each JSON object/array
jbe@149 943 // to allow NULL values returned as nil
jbe@149 944 lua_newtable(L);
jbe@138 945 lua_newtable(L); // metatable for ephemeron table
jbe@121 946 lua_pushliteral(L, "__mode");
jbe@121 947 lua_pushliteral(L, "k");
jbe@138 948 lua_rawset(L, -3);
jbe@138 949 lua_setmetatable(L, -2);
jbe@144 950 json_regstore(L, shadowtbl);
jbe@149 951 // return library module stored on lowest stack position:
jbe@138 952 lua_settop(L, 1);
jbe@121 953 return 1;
jbe@121 954 }

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