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annotate libraries/json/json.c @ 157:004d2d50419e

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Allow direct usage of json.null values in JSON library (for writing, not reading)
author jbe
date Thu Jul 31 03:45:33 2014 +0200 (2014-07-31)
parents 185e944182cb
children d42a7a840358
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@155 17 // generate dummy memory addresses that represents null values:
jbe@155 18 char json_nullmark;
jbe@155 19 #define json_isnullmark(L, i) (lua_touserdata((L), (i)) == &json_nullmark)
jbe@155 20 #define json_pushnullmark(L) lua_pushlightuserdata((L), &json_nullmark)
jbe@155 21
jbe@144 22 // macros for usage of Lua registry:
jbe@144 23 #define JSON_REGENT char
jbe@145 24 #define JSON_REGPOINTER void *
jbe@145 25 #define json_regpointer(x) (&json_registry.x)
jbe@151 26 #define json_regfetchpointer(L, x) lua_rawgetp((L), LUA_REGISTRYINDEX, (x))
jbe@151 27 #define json_regfetch(L, x) json_regfetchpointer(L, json_regpointer(x))
jbe@151 28 #define json_regstore(L, x) lua_rawsetp(L, LUA_REGISTRYINDEX, json_regpointer(x))
jbe@145 29
jbe@144 30 // generate dummy memory addresses that represent Lua objects
jbe@145 31 // via lightuserdata keys and LUA_REGISTRYINDEX:
jbe@144 32 static struct {
jbe@145 33 JSON_REGENT shadowtbl; // ephemeron table that maps tables to their corresponding shadow table
jbe@145 34 JSON_REGENT unknownmt; // metatable for tables that may be either JSON objects or JSON arrays
jbe@145 35 JSON_REGENT objectmt; // metatable for JSON objects
jbe@145 36 JSON_REGENT arraymt; // metatable for JSON arrays
jbe@144 37 } json_registry;
jbe@138 38
jbe@157 39 // returns the string "<JSON null marker>":
jbe@157 40 static int json_nullmark_tostring(lua_State *L) {
jbe@157 41 lua_pushliteral(L, "<JSON null marker>");
jbe@157 42 return 1;
jbe@157 43 }
jbe@157 44
jbe@145 45 // marks a Lua table as JSON object or JSON array:
jbe@136 46 // (returns its modified argument or a new table if argument is nil)
jbe@145 47 static int json_mark(lua_State *L, JSON_REGPOINTER mt) {
jbe@145 48 // check if argument is nil
jbe@136 49 if (lua_isnoneornil(L, 1)) {
jbe@145 50 // create new table at stack position 1:
jbe@136 51 lua_settop(L, 0);
jbe@136 52 lua_newtable(L);
jbe@145 53 // create shadow table (leaving previously created table on stack position 1):
jbe@144 54 json_regfetch(L, shadowtbl);
jbe@136 55 lua_pushvalue(L, 1);
jbe@136 56 lua_newtable(L);
jbe@143 57 lua_rawset(L, -3);
jbe@143 58 } else {
jbe@145 59 // push shadow table on top of stack:
jbe@144 60 json_regfetch(L, shadowtbl);
jbe@143 61 lua_pushvalue(L, 1);
jbe@143 62 lua_rawget(L, -2);
jbe@145 63 // if shadow table does not exist:
jbe@143 64 if (lua_isnil(L, -1)) {
jbe@145 65 // create shadow table and leave it on top of stack:
jbe@143 66 lua_newtable(L);
jbe@143 67 lua_pushvalue(L, 1);
jbe@143 68 lua_pushvalue(L, -2);
jbe@143 69 lua_rawset(L, -5);
jbe@143 70 }
jbe@145 71 // move elements from original table to shadow table (that's expected on top of stack):
jbe@143 72 for(lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
jbe@143 73 lua_pushvalue(L, -2);
jbe@143 74 lua_pushnil(L);
jbe@143 75 lua_rawset(L, 1);
jbe@143 76 lua_pushvalue(L, -2);
jbe@143 77 lua_pushvalue(L, -2);
jbe@143 78 lua_rawset(L, -5);
jbe@143 79 }
jbe@136 80 }
jbe@138 81 // discard everything but table to return:
jbe@138 82 lua_settop(L, 1);
jbe@136 83 // set metatable:
jbe@145 84 json_regfetchpointer(L, mt);
jbe@136 85 lua_setmetatable(L, 1);
jbe@138 86 // return table:
jbe@136 87 return 1;
jbe@136 88 }
jbe@136 89
jbe@136 90 // marks a table as JSON object:
jbe@136 91 // (returns its modified argument or a new table if argument is nil)
jbe@136 92 static int json_object(lua_State *L) {
jbe@145 93 return json_mark(L, json_regpointer(objectmt));
jbe@136 94 }
jbe@136 95
jbe@136 96 // marks a table as JSON array:
jbe@136 97 // (returns its modified argument or a new table if argument is nil)
jbe@136 98 static int json_array(lua_State *L) {
jbe@145 99 return json_mark(L, json_regpointer(arraymt));
jbe@136 100 }
jbe@136 101
jbe@145 102 // internal states of JSON parser:
jbe@124 103 #define JSON_STATE_VALUE 0
jbe@124 104 #define JSON_STATE_OBJECT_KEY 1
jbe@124 105 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
jbe@124 106 #define JSON_STATE_OBJECT_VALUE 3
jbe@124 107 #define JSON_STATE_OBJECT_SEPARATOR 4
jbe@124 108 #define JSON_STATE_ARRAY_VALUE 5
jbe@124 109 #define JSON_STATE_ARRAY_SEPARATOR 6
jbe@124 110 #define JSON_STATE_END 7
jbe@121 111
jbe@145 112 // special Lua stack indicies for json_import function:
jbe@138 113 #define json_import_objectmt_idx 2
jbe@138 114 #define json_import_arraymt_idx 3
jbe@138 115 #define json_import_shadowtbl_idx 4
jbe@138 116
jbe@136 117 // decodes a JSON document:
jbe@121 118 static int json_import(lua_State *L) {
jbe@136 119 const char *str; // string to parse
jbe@136 120 size_t total; // total length of string to parse
jbe@136 121 size_t pos = 0; // current position in string to parse
jbe@136 122 size_t level = 0; // nested levels of objects/arrays currently being processed
jbe@145 123 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
jbe@136 124 char c; // variable to store a single character to be processed
jbe@145 125 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
jbe@145 126 char *cbuf; // C buffer to decode JSON string values
jbe@136 127 size_t writepos; // write position of decoded strings in C buffer
jbe@152 128 size_t arraylen; // variable to temporarily store the array length
jbe@147 129 // stack shall contain one function argument:
jbe@138 130 lua_settop(L, 1);
jbe@147 131 // push objectmt onto stack position 2:
jbe@144 132 json_regfetch(L, objectmt);
jbe@147 133 // push arraymt onto stack position 3:
jbe@144 134 json_regfetch(L, arraymt);
jbe@147 135 // push shadowtbl onto stack position 4:
jbe@144 136 json_regfetch(L, shadowtbl);
jbe@136 137 // require string as first argument:
jbe@136 138 str = luaL_checklstring(L, 1, &total);
jbe@136 139 // if string contains a NULL byte, this is a syntax error
jbe@136 140 if (strlen(str) != total) goto json_import_syntax_error;
jbe@136 141 // main loop of parser:
jbe@136 142 json_import_loop:
jbe@136 143 // skip whitespace and store next character in variable 'c':
jbe@146 144 while (c = str[pos],
jbe@146 145 c == ' ' ||
jbe@146 146 c == '\f' ||
jbe@146 147 c == '\n' ||
jbe@146 148 c == '\r' ||
jbe@146 149 c == '\t' ||
jbe@146 150 c == '\v'
jbe@146 151 ) pos++;
jbe@136 152 // switch statement to handle certain (single) characters:
jbe@121 153 switch (c) {
jbe@136 154 // handle end of JSON document:
jbe@121 155 case 0:
jbe@136 156 // if end of JSON document was expected, then return top element of stack as result:
jbe@124 157 if (mode == JSON_STATE_END) return 1;
jbe@136 158 // otherwise, the JSON document was malformed:
jbe@121 159 json_import_unexpected_eof:
jbe@121 160 lua_pushnil(L);
jbe@121 161 if (level == 0) lua_pushliteral(L, "Empty string");
jbe@121 162 else lua_pushliteral(L, "Unexpected end of JSON document");
jbe@121 163 return 2;
jbe@136 164 // new JSON object:
jbe@121 165 case '{':
jbe@136 166 // if a JSON object is not expected here, then return an error:
jbe@146 167 if (
jbe@146 168 mode != JSON_STATE_VALUE &&
jbe@146 169 mode != JSON_STATE_OBJECT_VALUE &&
jbe@146 170 mode != JSON_STATE_ARRAY_VALUE
jbe@146 171 ) goto json_import_syntax_error;
jbe@136 172 // create JSON object on stack:
jbe@136 173 lua_newtable(L);
jbe@136 174 // set metatable of JSON object:
jbe@138 175 lua_pushvalue(L, json_import_objectmt_idx);
jbe@125 176 lua_setmetatable(L, -2);
jbe@136 177 // create internal shadow table on stack:
jbe@136 178 lua_newtable(L);
jbe@146 179 // register internal shadow table:
jbe@123 180 lua_pushvalue(L, -2);
jbe@123 181 lua_pushvalue(L, -2);
jbe@138 182 lua_rawset(L, json_import_shadowtbl_idx);
jbe@146 183 // expect object key (or end of object) to follow:
jbe@136 184 mode = JSON_STATE_OBJECT_KEY;
jbe@146 185 // jump to common code for opening JSON object and JSON array:
jbe@142 186 goto json_import_open;
jbe@136 187 // new JSON array:
jbe@121 188 case '[':
jbe@136 189 // if a JSON array is not expected here, then return an error:
jbe@146 190 if (
jbe@146 191 mode != JSON_STATE_VALUE &&
jbe@146 192 mode != JSON_STATE_OBJECT_VALUE &&
jbe@146 193 mode != JSON_STATE_ARRAY_VALUE
jbe@146 194 ) goto json_import_syntax_error;
jbe@136 195 // create JSON array on stack:
jbe@136 196 lua_newtable(L);
jbe@136 197 // set metatable of JSON array:
jbe@138 198 lua_pushvalue(L, json_import_arraymt_idx);
jbe@125 199 lua_setmetatable(L, -2);
jbe@136 200 // create internal shadow table on stack:
jbe@136 201 lua_newtable(L);
jbe@146 202 // register internal shadow table:
jbe@123 203 lua_pushvalue(L, -2);
jbe@123 204 lua_pushvalue(L, -2);
jbe@138 205 lua_rawset(L, json_import_shadowtbl_idx);
jbe@140 206 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
jbe@140 207 lua_pushnil(L);
jbe@146 208 // expect array value (or end of array) to follow:
jbe@142 209 mode = JSON_STATE_ARRAY_VALUE;
jbe@142 210 // continue with common code for opening JSON object and JSON array:
jbe@146 211 // common code for opening JSON object or JSON array:
jbe@142 212 json_import_open:
jbe@142 213 // limit nested levels:
jbe@142 214 if (level >= JSON_MAXDEPTH) {
jbe@142 215 lua_pushnil(L);
jbe@142 216 lua_pushliteral(L, "Too many nested JSON levels");
jbe@142 217 return 2;
jbe@142 218 }
jbe@142 219 // additional buffer overflow protection:
jbe@142 220 if (!lua_checkstack(L, LUA_MINSTACK))
jbe@142 221 return luaL_error(L, "Caught stack overflow in JSON import function (too many nested levels and stack size too small)");
jbe@136 222 // increment level:
jbe@121 223 level++;
jbe@142 224 // consume input character:
jbe@142 225 pos++;
jbe@121 226 goto json_import_loop;
jbe@136 227 // end of JSON object:
jbe@121 228 case '}':
jbe@136 229 // if end of JSON object is not expected here, then return an error:
jbe@146 230 if (
jbe@146 231 mode != JSON_STATE_OBJECT_KEY &&
jbe@146 232 mode != JSON_STATE_OBJECT_SEPARATOR
jbe@146 233 ) goto json_import_syntax_error;
jbe@136 234 // jump to common code for end of JSON object and JSON array:
jbe@121 235 goto json_import_close;
jbe@136 236 // end of JSON array:
jbe@121 237 case ']':
jbe@136 238 // if end of JSON array is not expected here, then return an error:
jbe@146 239 if (
jbe@146 240 mode != JSON_STATE_ARRAY_VALUE &&
jbe@146 241 mode != JSON_STATE_ARRAY_SEPARATOR
jbe@146 242 ) goto json_import_syntax_error;
jbe@146 243 // pop nil key/magic (that was needed to keep stack balance):
jbe@140 244 lua_pop(L, 1);
jbe@136 245 // continue with common code for end of JSON object and JSON array:
jbe@136 246 // common code for end of JSON object or JSON array:
jbe@121 247 json_import_close:
jbe@136 248 // consume input character:
jbe@121 249 pos++;
jbe@136 250 // pop shadow table:
jbe@136 251 lua_pop(L, 1);
jbe@136 252 // check if nested:
jbe@121 253 if (--level) {
jbe@146 254 // if nested,
jbe@146 255 // check if outer(!) structure is an array or object:
jbe@140 256 if (lua_isnil(L, -2)) {
jbe@136 257 // select array value processing:
jbe@124 258 mode = JSON_STATE_ARRAY_VALUE;
jbe@121 259 } else {
jbe@136 260 // select object value processing:
jbe@124 261 mode = JSON_STATE_OBJECT_VALUE;
jbe@121 262 }
jbe@136 263 // store value in outer structure:
jbe@121 264 goto json_import_process_value;
jbe@121 265 }
jbe@136 266 // if not nested, then expect end of JSON document and continue with loop:
jbe@136 267 mode = JSON_STATE_END;
jbe@121 268 goto json_import_loop;
jbe@136 269 // key terminator:
jbe@121 270 case ':':
jbe@136 271 // if key terminator is not expected here, then return an error:
jbe@124 272 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
jbe@121 273 goto json_import_syntax_error;
jbe@136 274 // consume input character:
jbe@121 275 pos++;
jbe@146 276 // expect object value to follow:
jbe@124 277 mode = JSON_STATE_OBJECT_VALUE;
jbe@146 278 // continue with loop:
jbe@121 279 goto json_import_loop;
jbe@136 280 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
jbe@121 281 case ',':
jbe@146 282 // branch according to parser state:
jbe@124 283 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
jbe@146 284 // expect an object key to follow:
jbe@124 285 mode = JSON_STATE_OBJECT_KEY;
jbe@124 286 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
jbe@146 287 // expect an array value to follow:
jbe@124 288 mode = JSON_STATE_ARRAY_VALUE;
jbe@121 289 } else {
jbe@136 290 // if value terminator is not expected here, then return an error:
jbe@136 291 goto json_import_syntax_error;
jbe@121 292 }
jbe@136 293 // consume input character:
jbe@121 294 pos++;
jbe@136 295 // continue with loop:
jbe@121 296 goto json_import_loop;
jbe@136 297 // string literal:
jbe@121 298 case '"':
jbe@146 299 // consume quote character:
jbe@146 300 pos++;
jbe@136 301 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
jbe@121 302 cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
jbe@121 303 writepos = 0;
jbe@146 304 // loop through the characters until encountering end quote:
jbe@121 305 while ((c = str[pos++]) != '"') {
jbe@121 306 if (c == 0) {
jbe@146 307 // handle unexpected end of JSON document:
jbe@121 308 goto json_import_unexpected_eof;
jbe@121 309 } else if (c < 32 || c == 127) {
jbe@136 310 // do not allow ASCII control characters:
jbe@136 311 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
jbe@136 312 // by this parser to allow different encodings than Unicode
jbe@121 313 lua_pushnil(L);
jbe@121 314 lua_pushliteral(L, "Unexpected control character in JSON string");
jbe@121 315 return 2;
jbe@121 316 } else if (c == '\\') {
jbe@136 317 // read next char after backslash escape:
jbe@121 318 c = str[pos++];
jbe@121 319 switch (c) {
jbe@136 320 // unexpected end-of-string:
jbe@121 321 case 0:
jbe@121 322 goto json_import_unexpected_eof;
jbe@136 323 // unescaping of quotation mark, slash, and backslash:
jbe@121 324 case '"':
jbe@121 325 case '/':
jbe@121 326 case '\\':
jbe@121 327 cbuf[writepos++] = c;
jbe@121 328 break;
jbe@136 329 // unescaping of backspace:
jbe@146 330 case 'b': cbuf[writepos++] = '\b'; break;
jbe@136 331 // unescaping of form-feed:
jbe@146 332 case 'f': cbuf[writepos++] = '\f'; break;
jbe@136 333 // unescaping of new-line:
jbe@146 334 case 'n': cbuf[writepos++] = '\n'; break;
jbe@136 335 // unescaping of carriage-return:
jbe@146 336 case 'r': cbuf[writepos++] = '\r'; break;
jbe@136 337 // unescaping of tabulator:
jbe@146 338 case 't': cbuf[writepos++] = '\t'; break;
jbe@136 339 // unescaping of UTF-16 characters
jbe@121 340 case 'u':
jbe@121 341 lua_pushnil(L);
jbe@121 342 lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet"); // TODO
jbe@121 343 return 2;
jbe@136 344 // unexpected escape sequence:
jbe@121 345 default:
jbe@121 346 lua_pushnil(L);
jbe@121 347 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
jbe@121 348 return 2;
jbe@121 349 }
jbe@121 350 } else {
jbe@136 351 // normal character:
jbe@121 352 cbuf[writepos++] = c;
jbe@121 353 }
jbe@121 354 }
jbe@136 355 // process buffer to Lua string:
jbe@121 356 luaL_pushresultsize(&luabuf, writepos);
jbe@136 357 // continue with processing of decoded string:
jbe@121 358 goto json_import_process_value;
jbe@121 359 }
jbe@136 360 // process values whose type is is not deducible from a single character:
jbe@136 361 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
jbe@146 362 // for numbers,
jbe@146 363 // use strtod() call to parse a (double precision) floating point number:
jbe@122 364 char *endptr;
jbe@122 365 double numval;
jbe@122 366 numval = strtod(str+pos, &endptr);
jbe@146 367 // catch parsing errors:
jbe@122 368 if (endptr == str+pos) goto json_import_syntax_error;
jbe@146 369 // consume characters that were parsed:
jbe@122 370 pos += endptr - (str+pos);
jbe@146 371 // push parsed (double precision) floating point number on Lua stack:
jbe@122 372 lua_pushnumber(L, numval);
jbe@122 373 } else if (!strncmp(str+pos, "true", 4)) {
jbe@136 374 // consume 4 input characters for "true":
jbe@121 375 pos += 4;
jbe@147 376 // put Lua true value onto stack:
jbe@136 377 lua_pushboolean(L, 1);
jbe@121 378 } else if (!strncmp(str+pos, "false", 5)) {
jbe@136 379 // consume 5 input characters for "false":
jbe@121 380 pos += 5;
jbe@147 381 // put Lua false value onto stack:
jbe@136 382 lua_pushboolean(L, 0);
jbe@121 383 } else if (!strncmp(str+pos, "null", 4)) {
jbe@136 384 // consume 4 input characters for "null":
jbe@136 385 pos += 4;
jbe@153 386 // different behavor for top-level and sub-levels:
jbe@153 387 if (level) {
jbe@153 388 // if sub-level,
jbe@153 389 // push special null-marker onto stack:
jbe@155 390 json_pushnullmark(L);
jbe@153 391 } else {
jbe@153 392 // if top-level,
jbe@153 393 // push nil onto stack:
jbe@153 394 lua_pushnil(L);
jbe@153 395 }
jbe@121 396 } else {
jbe@136 397 // all other cases are a syntax error:
jbe@121 398 goto json_import_syntax_error;
jbe@121 399 }
jbe@136 400 // process a decoded value or key value pair (expected on top of Lua stack):
jbe@136 401 json_import_process_value:
jbe@121 402 switch (mode) {
jbe@136 403 // an object key has been read:
jbe@124 404 case JSON_STATE_OBJECT_KEY:
jbe@136 405 // if an object key is not a string, then this is a syntax error:
jbe@121 406 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
jbe@146 407 // expect key terminator to follow:
jbe@124 408 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
jbe@146 409 // continue with loop:
jbe@121 410 goto json_import_loop;
jbe@136 411 // a key value pair has been read:
jbe@124 412 case JSON_STATE_OBJECT_VALUE:
jbe@136 413 // store key value pair in outer shadow table:
jbe@130 414 lua_rawset(L, -3);
jbe@146 415 // expect value terminator (or end of object) to follow:
jbe@124 416 mode = JSON_STATE_OBJECT_SEPARATOR;
jbe@146 417 // continue with loop:
jbe@121 418 goto json_import_loop;
jbe@136 419 // an array value has been read:
jbe@124 420 case JSON_STATE_ARRAY_VALUE:
jbe@152 421 // get current array length:
jbe@152 422 arraylen = lua_rawlen(L, -3);
jbe@152 423 // throw error if array would exceed INT_MAX elements:
jbe@152 424 // TODO: Lua 5.3 may support more elements
jbe@152 425 if (arraylen >= INT_MAX) {
jbe@152 426 lua_pushnil(L);
jbe@152 427 lua_pushfstring(L, "Array exceeded length of %d elements", INT_MAX);
jbe@152 428 }
jbe@136 429 // store value in outer shadow table:
jbe@152 430 lua_rawseti(L, -3, arraylen + 1);
jbe@146 431 // expect value terminator (or end of object) to follow:
jbe@124 432 mode = JSON_STATE_ARRAY_SEPARATOR;
jbe@146 433 // continue with loop
jbe@121 434 goto json_import_loop;
jbe@136 435 // a single value has been read:
jbe@124 436 case JSON_STATE_VALUE:
jbe@136 437 // leave value on top of stack, expect end of JSON document, and continue with loop:
jbe@124 438 mode = JSON_STATE_END;
jbe@121 439 goto json_import_loop;
jbe@121 440 }
jbe@146 441 // syntax error handling (reachable by goto statement):
jbe@136 442 json_import_syntax_error:
jbe@121 443 lua_pushnil(L);
jbe@121 444 lua_pushliteral(L, "Syntax error in JSON document");
jbe@121 445 return 2;
jbe@121 446 }
jbe@121 447
jbe@146 448 // special Lua stack indicies for json_path function:
jbe@138 449 #define json_path_shadowtbl_idx 1
jbe@146 450
jbe@146 451 // stack offset of arguments to json_path function:
jbe@155 452 #define json_path_idxshift 1
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@146 462 // store stack index of top of stack:
jbe@138 463 stacktop = lua_gettop(L);
jbe@146 464 // use first argument as "current value" (stored on top of stack):
jbe@138 465 lua_pushvalue(L, 1 + json_path_idxshift);
jbe@146 466 // process each "path key" (2nd argument and following arguments):
jbe@138 467 while (idx <= stacktop) {
jbe@146 468 // if "current value" (on top of stack) is nil, then the path cannot be walked and nil is returned:
jbe@137 469 if (lua_isnil(L, -1)) return 1;
jbe@137 470 // try to get shadow table of "current value":
jbe@130 471 lua_pushvalue(L, -1);
jbe@138 472 lua_rawget(L, json_path_shadowtbl_idx);
jbe@126 473 if (lua_isnil(L, -1)) {
jbe@137 474 // if no shadow table is found,
jbe@130 475 if (lua_type(L, -1) == LUA_TTABLE) {
jbe@146 476 // and if "current value" is a table,
jbe@146 477 // drop nil from stack:
jbe@146 478 lua_pop(L, 1);
jbe@137 479 // get "next value" using the "path key":
jbe@130 480 lua_pushvalue(L, idx++);
jbe@130 481 lua_gettable(L, -2);
jbe@130 482 } else {
jbe@137 483 // if "current value" is not a table,
jbe@146 484 // then the path cannot be walked and nil (already on top of stack) is returned:
jbe@137 485 return 1;
jbe@130 486 }
jbe@130 487 } else {
jbe@137 488 // if a shadow table is found,
jbe@137 489 // set "current value" to its shadow table:
jbe@130 490 lua_replace(L, -2);
jbe@137 491 // get "next value" using the "path key":
jbe@130 492 lua_pushvalue(L, idx++);
jbe@130 493 lua_rawget(L, -2);
jbe@126 494 }
jbe@137 495 // the "next value" replaces the "current value":
jbe@130 496 lua_replace(L, -2);
jbe@126 497 }
jbe@137 498 if (!type_mode) {
jbe@137 499 // if a value (and not its type) was requested,
jbe@137 500 // check if value is the null-marker, and store nil on top of Lua stack in that case:
jbe@155 501 if (json_isnullmark(L, -1)) lua_pushnil(L);
jbe@137 502 } else {
jbe@137 503 // if the type was requested,
jbe@137 504 // check if value is the null-marker:
jbe@155 505 if (json_isnullmark(L, -1)) {
jbe@137 506 // if yes, store string "null" on top of Lua stack:
jbe@130 507 lua_pushliteral(L, "null");
jbe@137 508 } else {
jbe@137 509 // otherwise,
jbe@138 510 // check if metatable indicates "object" or "array":
jbe@138 511 if (lua_getmetatable(L, -1)) {
jbe@144 512 json_regfetch(L, objectmt);
jbe@138 513 if (lua_rawequal(L, -2, -1)) {
jbe@146 514 // if value has metatable for JSON objects,
jbe@138 515 // return string "object":
jbe@138 516 lua_pushliteral(L, "object");
jbe@138 517 return 1;
jbe@138 518 }
jbe@144 519 json_regfetch(L, arraymt);
jbe@138 520 if (lua_rawequal(L, -3, -1)) {
jbe@146 521 // if value has metatable for JSON arrays,
jbe@146 522 // return string "object":
jbe@138 523 lua_pushliteral(L, "array");
jbe@138 524 return 1;
jbe@138 525 }
jbe@146 526 // remove 3 metatables (one of the value, two for comparison) from stack:
jbe@138 527 lua_pop(L, 3);
jbe@138 528 }
jbe@138 529 // otherwise, get the Lua type:
jbe@138 530 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
jbe@126 531 }
jbe@126 532 }
jbe@137 533 // return the top most value on the Lua stack:
jbe@137 534 return 1;
jbe@130 535 }
jbe@130 536
jbe@147 537 // gets a value from a JSON document (passed as first argument)
jbe@147 538 // using a path (passed as variable number of keys after first argument):
jbe@130 539 static int json_get(lua_State *L) {
jbe@137 540 return json_path(L, 0);
jbe@130 541 }
jbe@130 542
jbe@147 543 // gets a value's type from a JSON document (passed as first argument)
jbe@147 544 // using a path (variable number of keys after first argument):
jbe@130 545 static int json_type(lua_State *L) {
jbe@137 546 return json_path(L, 1);
jbe@130 547 }
jbe@130 548
jbe@147 549 // checks if a value in a JSON document (first argument) is
jbe@147 550 // explicitly set to null:
jbe@130 551 static int json_isnull(lua_State *L) {
jbe@137 552 const char *jsontype;
jbe@147 553 // call json_type function with variable arguments:
jbe@138 554 lua_pushcfunction(L, json_type);
jbe@137 555 lua_insert(L, 1);
jbe@137 556 lua_call(L, lua_gettop(L) - 1, 1);
jbe@147 557 // return true if result equals to string "null", otherwise return false:
jbe@137 558 jsontype = lua_tostring(L, -1);
jbe@137 559 if (jsontype && !strcmp(jsontype, "null")) lua_pushboolean(L, 1);
jbe@137 560 else lua_pushboolean(L, 0);
jbe@137 561 return 1;
jbe@130 562 }
jbe@130 563
jbe@146 564 // special Lua stack indicies for json_setnull function:
jbe@138 565 #define json_setnull_unknownmt_idx 3
jbe@138 566 #define json_setnull_objectmt_idx 4
jbe@138 567 #define json_setnull_arraymt_idx 5
jbe@138 568 #define json_setnull_shadowtbl_idx 6
jbe@138 569
jbe@147 570 // sets a value in a JSON object or JSON array explicitly to null:
jbe@147 571 // NOTE: JSON null is different than absence of a key
jbe@131 572 static int json_setnull(lua_State *L) {
jbe@147 573 // stack shall contain two function arguments:
jbe@131 574 lua_settop(L, 2);
jbe@148 575 // push unknownmt onto stack position 3:
jbe@144 576 json_regfetch(L, unknownmt);
jbe@148 577 // push objectmt onto stack position 4:
jbe@144 578 json_regfetch(L, objectmt);
jbe@148 579 // push arraymt onto stack position 5:
jbe@144 580 json_regfetch(L, arraymt);
jbe@148 581 // push shadowtbl onto stack position 6:
jbe@144 582 json_regfetch(L, shadowtbl);
jbe@147 583 // set metatable if necessary (leaves unknown number of elements on stack):
jbe@138 584 if (
jbe@147 585 !lua_getmetatable(L, 1) || (
jbe@147 586 !lua_rawequal(L, -1, json_setnull_unknownmt_idx) &&
jbe@147 587 !lua_rawequal(L, -1, json_setnull_objectmt_idx) &&
jbe@147 588 !lua_rawequal(L, -1, json_setnull_arraymt_idx)
jbe@147 589 )
jbe@138 590 ) {
jbe@138 591 lua_pushvalue(L, json_setnull_unknownmt_idx);
jbe@138 592 lua_setmetatable(L, 1);
jbe@138 593 }
jbe@147 594 // try to get shadow table:
jbe@131 595 lua_pushvalue(L, 1);
jbe@138 596 lua_rawget(L, json_setnull_shadowtbl_idx);
jbe@131 597 if (lua_isnil(L, -1)) {
jbe@147 598 // if no shadow table is found,
jbe@147 599 // create new shadow table (and leave it on top of stack):
jbe@131 600 lua_newtable(L);
jbe@147 601 // register shadow table:
jbe@131 602 lua_pushvalue(L, 1);
jbe@131 603 lua_pushvalue(L, -2);
jbe@138 604 lua_rawset(L, json_setnull_shadowtbl_idx);
jbe@131 605 }
jbe@147 606 // push key (second argument) and null-marker after shadow table onto stack:
jbe@131 607 lua_pushvalue(L, 2);
jbe@155 608 json_pushnullmark(L);
jbe@147 609 // store key and null-marker in shadow table:
jbe@131 610 lua_rawset(L, -3);
jbe@147 611 // return nothing:
jbe@131 612 return 0;
jbe@131 613 }
jbe@131 614
jbe@147 615 // returns the length of a JSON array (or zero for a table without numeric keys):
jbe@130 616 static int json_len(lua_State *L) {
jbe@147 617 // stack shall contain one function argument:
jbe@130 618 lua_settop(L, 1);
jbe@148 619 // try to get corresponding shadow table for first argument:
jbe@144 620 json_regfetch(L, shadowtbl);
jbe@130 621 lua_pushvalue(L, 1);
jbe@138 622 lua_rawget(L, -2);
jbe@147 623 // if shadow table does not exist, return length of argument, else length of shadow table:
jbe@147 624 lua_pushnumber(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
jbe@123 625 return 1;
jbe@123 626 }
jbe@123 627
jbe@130 628 static int json_index(lua_State *L) {
jbe@148 629 // stack shall contain two function arguments:
jbe@130 630 lua_settop(L, 2);
jbe@155 631 // get corresponding shadow table for first argument:
jbe@144 632 json_regfetch(L, shadowtbl);
jbe@130 633 lua_pushvalue(L, 1);
jbe@155 634 lua_rawget(L, -2);
jbe@148 635 // throw error if no shadow table was found:
jbe@139 636 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@148 637 // use key passed as second argument to lookup value in shadow table:
jbe@130 638 lua_pushvalue(L, 2);
jbe@130 639 lua_rawget(L, -2);
jbe@148 640 // if value is null-marker, then push nil onto stack:
jbe@155 641 if (json_isnullmark(L, -1)) lua_pushnil(L);
jbe@148 642 // return either looked up value, or nil
jbe@127 643 return 1;
jbe@127 644 }
jbe@127 645
jbe@130 646 static int json_newindex(lua_State *L) {
jbe@148 647 // stack shall contain three function arguments:
jbe@130 648 lua_settop(L, 3);
jbe@148 649 // get corresponding shadow table for first argument:
jbe@144 650 json_regfetch(L, shadowtbl);
jbe@123 651 lua_pushvalue(L, 1);
jbe@143 652 lua_rawget(L, -2);
jbe@148 653 // throw error if no shadow table was found:
jbe@130 654 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@148 655 // replace first argument with shadow table:
jbe@130 656 lua_replace(L, 1);
jbe@148 657 // reset stack and use second and third argument to write to shadow table:
jbe@139 658 lua_settop(L, 3);
jbe@130 659 lua_rawset(L, 1);
jbe@148 660 // return nothing:
jbe@148 661 return 0;
jbe@121 662 }
jbe@121 663
jbe@135 664 static int json_pairs_iterfunc(lua_State *L) {
jbe@149 665 // stack shall contain two function arguments:
jbe@135 666 lua_settop(L, 2);
jbe@155 667 // get corresponding shadow table for first argument:
jbe@144 668 json_regfetch(L, shadowtbl);
jbe@135 669 lua_pushvalue(L, 1);
jbe@155 670 lua_rawget(L, -2);
jbe@149 671 // throw error if no shadow table was found:
jbe@135 672 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@149 673 // get next key value pair from shadow table (using previous key from argument 2)
jbe@149 674 // and return nothing if there is no next pair:
jbe@135 675 lua_pushvalue(L, 2);
jbe@135 676 if (!lua_next(L, -2)) return 0;
jbe@149 677 // replace null-marker with nil:
jbe@155 678 if (json_isnullmark(L, -1)) {
jbe@135 679 lua_pop(L, 1);
jbe@135 680 lua_pushnil(L);
jbe@135 681 }
jbe@149 682 // return key and value (or key and nil, if null-marker was found):
jbe@135 683 return 2;
jbe@135 684 }
jbe@135 685
jbe@149 686 // returns a triple such that 'for key, value in pairs(obj) do ... end'
jbe@149 687 // iterates through all key value pairs (including JSON null keys represented as Lua nil):
jbe@135 688 static int json_pairs(lua_State *L) {
jbe@149 689 // return triple of function json_pairs_iterfunc, first argument, and nil:
jbe@139 690 lua_pushcfunction(L, json_pairs_iterfunc);
jbe@135 691 lua_pushvalue(L, 1);
jbe@135 692 lua_pushnil(L);
jbe@135 693 return 3;
jbe@135 694 }
jbe@135 695
jbe@134 696 static int json_ipairs_iterfunc(lua_State *L) {
jbe@152 697 lua_Integer idx;
jbe@149 698 // stack shall contain two function arguments:
jbe@134 699 lua_settop(L, 2);
jbe@149 700 // calculate new index by incrementing second argument:
jbe@134 701 idx = lua_tointeger(L, 2) + 1;
jbe@149 702 // get corresponding shadow table for first argument:
jbe@155 703 json_regfetch(L, shadowtbl);
jbe@134 704 lua_pushvalue(L, 1);
jbe@155 705 lua_rawget(L, -2);
jbe@149 706 // throw error if no shadow table was found:
jbe@134 707 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@149 708 // do integer lookup in shadow table:
jbe@134 709 lua_rawgeti(L, -1, idx);
jbe@149 710 // return nothing if there was no value:
jbe@134 711 if (lua_isnil(L, -1)) return 0;
jbe@149 712 // return new index and
jbe@149 713 // either the looked up value if it is not equal to the null-marker
jbe@149 714 // or nil instead of null-marker:
jbe@134 715 lua_pushinteger(L, idx);
jbe@155 716 if (json_isnullmark(L, -2)) lua_pushnil(L);
jbe@134 717 else lua_pushvalue(L, -2);
jbe@134 718 return 2;
jbe@134 719 }
jbe@134 720
jbe@149 721 // returns a triple such that 'for idx, value in ipairs(ary) do ... end'
jbe@149 722 // iterates through all values (including JSON null represented as Lua nil):
jbe@134 723 static int json_ipairs(lua_State *L) {
jbe@149 724 // return triple of function json_ipairs_iterfunc, first argument, and zero:
jbe@139 725 lua_pushcfunction(L, json_ipairs_iterfunc);
jbe@134 726 lua_pushvalue(L, 1);
jbe@134 727 lua_pushinteger(L, 0);
jbe@134 728 return 3;
jbe@134 729 }
jbe@134 730
jbe@154 731 #define JSON_TABLETYPE_UNKNOWN 0
jbe@154 732 #define JSON_TABLETYPE_OBJECT 1
jbe@154 733 #define JSON_TABLETYPE_ARRAY 2
jbe@154 734
jbe@154 735 static int json_export(lua_State *L) {
jbe@154 736 lua_Number num;
jbe@154 737 const char *str;
jbe@154 738 unsigned char c;
jbe@154 739 size_t strlen;
jbe@154 740 size_t pos = 0;
jbe@154 741 luaL_Buffer buf;
jbe@154 742 char hexcode[7]; // backslash, character 'u', 4 hex digits, and terminating NULL byte
jbe@154 743 int luatype;
jbe@154 744 int tabletype = JSON_TABLETYPE_UNKNOWN;
jbe@154 745 int needsep = 0;
jbe@154 746 lua_Integer idx;
jbe@154 747 lua_settop(L, 1);
jbe@157 748 if (json_isnullmark(L, 1)) {
jbe@157 749 lua_pushnil(L);
jbe@157 750 lua_replace(L, 1);
jbe@157 751 }
jbe@154 752 switch (lua_type(L, 1)) {
jbe@154 753 case LUA_TNIL:
jbe@154 754 lua_pushliteral(L, "null");
jbe@154 755 return 1;
jbe@154 756 case LUA_TNUMBER:
jbe@154 757 num = lua_tonumber(L, 1);
jbe@154 758 if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
jbe@154 759 if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
jbe@154 760 lua_tostring(L, 1);
jbe@154 761 return 1;
jbe@154 762 case LUA_TBOOLEAN:
jbe@154 763 if (lua_toboolean(L, 1)) lua_pushliteral(L, "true");
jbe@154 764 else lua_pushliteral(L, "false");
jbe@154 765 return 1;
jbe@154 766 case LUA_TSTRING:
jbe@154 767 str = lua_tolstring(L, 1, &strlen);
jbe@154 768 luaL_buffinit(L, &buf);
jbe@154 769 luaL_addchar(&buf, '"');
jbe@154 770 while (pos < strlen) {
jbe@154 771 c = str[pos++];
jbe@154 772 if (c == '"') luaL_addstring(&buf, "\\\"");
jbe@154 773 else if (c == '\\') luaL_addstring(&buf, "\\\\");
jbe@154 774 else if (c == 127) luaL_addstring(&buf, "\\u007F");
jbe@154 775 else if (c >= 32) luaL_addchar(&buf, c);
jbe@154 776 else if (c == '\b') luaL_addstring(&buf, "\\b");
jbe@154 777 else if (c == '\f') luaL_addstring(&buf, "\\f");
jbe@154 778 else if (c == '\n') luaL_addstring(&buf, "\\n");
jbe@154 779 else if (c == '\r') luaL_addstring(&buf, "\\r");
jbe@154 780 else if (c == '\t') luaL_addstring(&buf, "\\t");
jbe@154 781 else if (c == '\v') luaL_addstring(&buf, "\\v");
jbe@154 782 else {
jbe@154 783 sprintf(hexcode, "\\u%04X", c);
jbe@154 784 luaL_addstring(&buf, hexcode);
jbe@154 785 }
jbe@154 786 }
jbe@154 787 luaL_addchar(&buf, '"');
jbe@154 788 luaL_pushresult(&buf);
jbe@154 789 return 1;
jbe@154 790 case LUA_TTABLE:
jbe@154 791 if (lua_getmetatable(L, 1)) {
jbe@154 792 json_regfetch(L, objectmt);
jbe@154 793 if (lua_rawequal(L, -2, -1)) {
jbe@154 794 tabletype = JSON_TABLETYPE_OBJECT;
jbe@154 795 } else {
jbe@154 796 json_regfetch(L, arraymt);
jbe@154 797 if (lua_rawequal(L, -3, -1)) tabletype = JSON_TABLETYPE_ARRAY;
jbe@154 798 }
jbe@154 799 }
jbe@154 800 json_regfetch(L, shadowtbl);
jbe@154 801 lua_pushvalue(L, 1);
jbe@154 802 lua_rawget(L, -2);
jbe@154 803 if (!lua_isnil(L, -1)) lua_replace(L, 1);
jbe@154 804 lua_settop(L, 1);
jbe@154 805 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
jbe@154 806 for (lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
jbe@154 807 luatype = lua_type(L, -2);
jbe@154 808 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
jbe@154 809 if (luatype == LUA_TSTRING) tabletype = JSON_TABLETYPE_OBJECT;
jbe@154 810 else if (luatype == LUA_TNUMBER) tabletype = JSON_TABLETYPE_ARRAY;
jbe@154 811 } else if (
jbe@154 812 (tabletype == JSON_TABLETYPE_OBJECT && luatype == LUA_TNUMBER) ||
jbe@154 813 (tabletype == JSON_TABLETYPE_ARRAY && luatype == LUA_TSTRING)
jbe@154 814 ) {
jbe@154 815 goto json_export_tabletype_error;
jbe@154 816 }
jbe@154 817 }
jbe@154 818 }
jbe@154 819 switch (tabletype) {
jbe@154 820 case JSON_TABLETYPE_OBJECT:
jbe@154 821 lua_settop(L, 3);
jbe@154 822 luaL_buffinit(L, &buf);
jbe@154 823 luaL_addchar(&buf, '{');
jbe@154 824 for (lua_pushnil(L); lua_next(L, 1); ) {
jbe@154 825 if (lua_type(L, -2) == LUA_TSTRING) {
jbe@154 826 lua_replace(L, 3);
jbe@154 827 lua_replace(L, 2);
jbe@154 828 if (needsep) luaL_addchar(&buf, ',');
jbe@154 829 else needsep = 1;
jbe@154 830 lua_pushcfunction(L, json_export);
jbe@154 831 lua_pushvalue(L, 2);
jbe@154 832 lua_call(L, 1, 1);
jbe@154 833 luaL_addvalue(&buf);
jbe@154 834 luaL_addchar(&buf, ':');
jbe@155 835 if (json_isnullmark(L, 3)) {
jbe@154 836 luaL_addstring(&buf, "null");
jbe@154 837 } else {
jbe@154 838 lua_pushcfunction(L, json_export);
jbe@154 839 lua_pushvalue(L, 3);
jbe@154 840 lua_call(L, 1, 1);
jbe@154 841 luaL_addvalue(&buf);
jbe@154 842 }
jbe@154 843 lua_pushvalue(L, 2);
jbe@154 844 } else {
jbe@154 845 lua_pop(L, 1);
jbe@154 846 }
jbe@154 847 }
jbe@154 848 luaL_addchar(&buf, '}');
jbe@154 849 luaL_pushresult(&buf);
jbe@154 850 return 1;
jbe@154 851 case JSON_TABLETYPE_ARRAY:
jbe@154 852 lua_settop(L, 2);
jbe@154 853 luaL_buffinit(L, &buf);
jbe@154 854 luaL_addchar(&buf, '[');
jbe@154 855 for (idx = 1; ; idx++) {
jbe@154 856 lua_rawgeti(L, 1, idx);
jbe@154 857 if (lua_isnil(L, -1)) {
jbe@154 858 lua_pop(L, 1);
jbe@154 859 break;
jbe@154 860 }
jbe@154 861 lua_replace(L, 2);
jbe@154 862 if (needsep) luaL_addchar(&buf, ',');
jbe@154 863 else needsep = 1;
jbe@154 864 lua_pushcfunction(L, json_export);
jbe@154 865 lua_pushvalue(L, 2);
jbe@154 866 lua_call(L, 1, 1);
jbe@154 867 luaL_addvalue(&buf);
jbe@154 868 }
jbe@154 869 luaL_addchar(&buf, ']');
jbe@154 870 luaL_pushresult(&buf);
jbe@154 871 return 1;
jbe@154 872 }
jbe@154 873 json_export_tabletype_error:
jbe@154 874 return luaL_error(L, "JSON export not possible for ambiguous table (cannot decide whether it is an object or array)");
jbe@154 875 }
jbe@154 876 return luaL_error(L, "JSON export not possible for values of type \"%s\"", lua_typename(L, lua_type(L, 1)));
jbe@154 877 }
jbe@154 878
jbe@149 879 // functions in library module:
jbe@121 880 static const struct luaL_Reg json_module_functions[] = {
jbe@133 881 {"object", json_object},
jbe@133 882 {"array", json_array},
jbe@121 883 {"import", json_import},
jbe@154 884 {"export", json_export},
jbe@130 885 {"get", json_get},
jbe@127 886 {"type", json_type},
jbe@123 887 {"isnull", json_isnull},
jbe@131 888 {"setnull", json_setnull},
jbe@121 889 {NULL, NULL}
jbe@121 890 };
jbe@121 891
jbe@149 892 // metamethods for JSON objects, JSON arrays, and unknown JSON collections (object or array):
jbe@126 893 static const struct luaL_Reg json_metatable_functions[] = {
jbe@130 894 {"__len", json_len},
jbe@130 895 {"__index", json_index},
jbe@130 896 {"__newindex", json_newindex},
jbe@135 897 {"__pairs", json_pairs},
jbe@134 898 {"__ipairs", json_ipairs},
jbe@126 899 {NULL, NULL}
jbe@126 900 };
jbe@126 901
jbe@157 902 // metamethods for JSON null marker:
jbe@157 903 static const struct luaL_Reg json_nullmark_metamethods[] = {
jbe@157 904 {"__tostring", json_nullmark_tostring},
jbe@157 905 {NULL, NULL}
jbe@157 906 };
jbe@157 907
jbe@149 908 // initializes json library:
jbe@121 909 int luaopen_json(lua_State *L) {
jbe@149 910 // empty stack:
jbe@126 911 lua_settop(L, 0);
jbe@149 912 // push library module onto stack position 1:
jbe@149 913 lua_newtable(L);
jbe@149 914 // register library functions:
jbe@149 915 luaL_setfuncs(L, json_module_functions, 0);
jbe@149 916 // create and store unknownmt:
jbe@138 917 lua_newtable(L);
jbe@138 918 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 919 json_regstore(L, unknownmt);
jbe@149 920 // create and store objectmt:
jbe@138 921 lua_newtable(L);
jbe@138 922 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 923 json_regstore(L, objectmt);
jbe@149 924 // create and store arraymt:
jbe@138 925 lua_newtable(L);
jbe@138 926 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 927 json_regstore(L, arraymt);
jbe@149 928 // create and store ephemeron table to store shadow tables for each JSON object/array
jbe@149 929 // to allow NULL values returned as nil
jbe@149 930 lua_newtable(L);
jbe@138 931 lua_newtable(L); // metatable for ephemeron table
jbe@121 932 lua_pushliteral(L, "__mode");
jbe@121 933 lua_pushliteral(L, "k");
jbe@138 934 lua_rawset(L, -3);
jbe@138 935 lua_setmetatable(L, -2);
jbe@144 936 json_regstore(L, shadowtbl);
jbe@157 937 // set metatable of null marker and make it available through library module:
jbe@157 938 json_pushnullmark(L);
jbe@157 939 lua_newtable(L);
jbe@157 940 luaL_setfuncs(L, json_nullmark_metamethods, 0);
jbe@157 941 lua_setmetatable(L, -2);
jbe@157 942 lua_setfield(L, 1, "null");
jbe@157 943 // return library module (that's expected on top of stack):
jbe@121 944 return 1;
jbe@121 945 }

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