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annotate libraries/json/json.c @ 160:d5e5e8a9b79a

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Added __tostring metamethod to JSON arrays and JSON objects
author jbe
date Thu Jul 31 03:57:11 2014 +0200 (2014-07-31)
parents ddb9b9b0d210
children d476b3c8960d
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 objectmt; // metatable for JSON objects
jbe@145 35 JSON_REGENT arraymt; // metatable for JSON arrays
jbe@144 36 } json_registry;
jbe@138 37
jbe@157 38 // returns the string "<JSON null marker>":
jbe@157 39 static int json_nullmark_tostring(lua_State *L) {
jbe@157 40 lua_pushliteral(L, "<JSON null marker>");
jbe@157 41 return 1;
jbe@157 42 }
jbe@157 43
jbe@145 44 // marks a Lua table as JSON object or JSON array:
jbe@136 45 // (returns its modified argument or a new table if argument is nil)
jbe@145 46 static int json_mark(lua_State *L, JSON_REGPOINTER mt) {
jbe@145 47 // check if argument is nil
jbe@136 48 if (lua_isnoneornil(L, 1)) {
jbe@145 49 // create new table at stack position 1:
jbe@136 50 lua_settop(L, 0);
jbe@136 51 lua_newtable(L);
jbe@145 52 // create shadow table (leaving previously created table on stack position 1):
jbe@144 53 json_regfetch(L, shadowtbl);
jbe@136 54 lua_pushvalue(L, 1);
jbe@136 55 lua_newtable(L);
jbe@143 56 lua_rawset(L, -3);
jbe@143 57 } else {
jbe@145 58 // push shadow table on top of stack:
jbe@144 59 json_regfetch(L, shadowtbl);
jbe@143 60 lua_pushvalue(L, 1);
jbe@143 61 lua_rawget(L, -2);
jbe@145 62 // if shadow table does not exist:
jbe@143 63 if (lua_isnil(L, -1)) {
jbe@145 64 // create shadow table and leave it on top of stack:
jbe@143 65 lua_newtable(L);
jbe@143 66 lua_pushvalue(L, 1);
jbe@143 67 lua_pushvalue(L, -2);
jbe@143 68 lua_rawset(L, -5);
jbe@143 69 }
jbe@145 70 // move elements from original table to shadow table (that's expected on top of stack):
jbe@143 71 for(lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
jbe@143 72 lua_pushvalue(L, -2);
jbe@143 73 lua_pushnil(L);
jbe@143 74 lua_rawset(L, 1);
jbe@143 75 lua_pushvalue(L, -2);
jbe@143 76 lua_pushvalue(L, -2);
jbe@143 77 lua_rawset(L, -5);
jbe@143 78 }
jbe@136 79 }
jbe@138 80 // discard everything but table to return:
jbe@138 81 lua_settop(L, 1);
jbe@136 82 // set metatable:
jbe@145 83 json_regfetchpointer(L, mt);
jbe@136 84 lua_setmetatable(L, 1);
jbe@138 85 // return table:
jbe@136 86 return 1;
jbe@136 87 }
jbe@136 88
jbe@136 89 // marks a table as JSON object:
jbe@136 90 // (returns its modified argument or a new table if argument is nil)
jbe@136 91 static int json_object(lua_State *L) {
jbe@145 92 return json_mark(L, json_regpointer(objectmt));
jbe@136 93 }
jbe@136 94
jbe@136 95 // marks a table as JSON array:
jbe@136 96 // (returns its modified argument or a new table if argument is nil)
jbe@136 97 static int json_array(lua_State *L) {
jbe@145 98 return json_mark(L, json_regpointer(arraymt));
jbe@136 99 }
jbe@136 100
jbe@145 101 // internal states of JSON parser:
jbe@124 102 #define JSON_STATE_VALUE 0
jbe@124 103 #define JSON_STATE_OBJECT_KEY 1
jbe@124 104 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
jbe@124 105 #define JSON_STATE_OBJECT_VALUE 3
jbe@124 106 #define JSON_STATE_OBJECT_SEPARATOR 4
jbe@124 107 #define JSON_STATE_ARRAY_VALUE 5
jbe@124 108 #define JSON_STATE_ARRAY_SEPARATOR 6
jbe@124 109 #define JSON_STATE_END 7
jbe@121 110
jbe@145 111 // special Lua stack indicies for json_import function:
jbe@138 112 #define json_import_objectmt_idx 2
jbe@138 113 #define json_import_arraymt_idx 3
jbe@138 114 #define json_import_shadowtbl_idx 4
jbe@138 115
jbe@136 116 // decodes a JSON document:
jbe@121 117 static int json_import(lua_State *L) {
jbe@136 118 const char *str; // string to parse
jbe@136 119 size_t total; // total length of string to parse
jbe@136 120 size_t pos = 0; // current position in string to parse
jbe@136 121 size_t level = 0; // nested levels of objects/arrays currently being processed
jbe@145 122 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
jbe@136 123 char c; // variable to store a single character to be processed
jbe@145 124 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
jbe@145 125 char *cbuf; // C buffer to decode JSON string values
jbe@136 126 size_t writepos; // write position of decoded strings in C buffer
jbe@152 127 size_t arraylen; // variable to temporarily store the array length
jbe@147 128 // stack shall contain one function argument:
jbe@138 129 lua_settop(L, 1);
jbe@147 130 // push objectmt onto stack position 2:
jbe@144 131 json_regfetch(L, objectmt);
jbe@147 132 // push arraymt onto stack position 3:
jbe@144 133 json_regfetch(L, arraymt);
jbe@147 134 // push shadowtbl onto stack position 4:
jbe@144 135 json_regfetch(L, shadowtbl);
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@155 389 json_pushnullmark(L);
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@146 449
jbe@146 450 // stack offset of arguments to json_path function:
jbe@155 451 #define json_path_idxshift 1
jbe@138 452
jbe@146 453 // gets a value or its type from a JSON document (passed as first argument)
jbe@147 454 // using a path (passed as variable number of keys after first argument):
jbe@137 455 static int json_path(lua_State *L, int type_mode) {
jbe@146 456 int stacktop; // stack index of top of stack (after shifting)
jbe@146 457 int idx = 2 + json_path_idxshift; // stack index of current argument to process
jbe@148 458 // insert shadowtbl into stack at position 1 (shifting the arguments):
jbe@144 459 json_regfetch(L, shadowtbl);
jbe@138 460 lua_insert(L, 1);
jbe@146 461 // store stack index of top of stack:
jbe@138 462 stacktop = lua_gettop(L);
jbe@146 463 // use first argument as "current value" (stored on top of stack):
jbe@138 464 lua_pushvalue(L, 1 + json_path_idxshift);
jbe@146 465 // process each "path key" (2nd argument and following arguments):
jbe@138 466 while (idx <= stacktop) {
jbe@146 467 // if "current value" (on top of stack) is nil, then the path cannot be walked and nil is returned:
jbe@137 468 if (lua_isnil(L, -1)) return 1;
jbe@137 469 // try to get shadow table of "current value":
jbe@130 470 lua_pushvalue(L, -1);
jbe@138 471 lua_rawget(L, json_path_shadowtbl_idx);
jbe@126 472 if (lua_isnil(L, -1)) {
jbe@137 473 // if no shadow table is found,
jbe@130 474 if (lua_type(L, -1) == LUA_TTABLE) {
jbe@146 475 // and if "current value" is a table,
jbe@146 476 // drop nil from stack:
jbe@146 477 lua_pop(L, 1);
jbe@137 478 // get "next value" using the "path key":
jbe@130 479 lua_pushvalue(L, idx++);
jbe@130 480 lua_gettable(L, -2);
jbe@130 481 } else {
jbe@137 482 // if "current value" is not a table,
jbe@146 483 // then the path cannot be walked and nil (already on top of stack) is returned:
jbe@137 484 return 1;
jbe@130 485 }
jbe@130 486 } else {
jbe@137 487 // if a shadow table is found,
jbe@137 488 // set "current value" to its shadow table:
jbe@130 489 lua_replace(L, -2);
jbe@137 490 // get "next value" using the "path key":
jbe@130 491 lua_pushvalue(L, idx++);
jbe@130 492 lua_rawget(L, -2);
jbe@126 493 }
jbe@137 494 // the "next value" replaces the "current value":
jbe@130 495 lua_replace(L, -2);
jbe@126 496 }
jbe@137 497 if (!type_mode) {
jbe@137 498 // if a value (and not its type) was requested,
jbe@137 499 // check if value is the null-marker, and store nil on top of Lua stack in that case:
jbe@155 500 if (json_isnullmark(L, -1)) lua_pushnil(L);
jbe@137 501 } else {
jbe@137 502 // if the type was requested,
jbe@137 503 // check if value is the null-marker:
jbe@155 504 if (json_isnullmark(L, -1)) {
jbe@137 505 // if yes, store string "null" on top of Lua stack:
jbe@130 506 lua_pushliteral(L, "null");
jbe@137 507 } else {
jbe@137 508 // otherwise,
jbe@138 509 // check if metatable indicates "object" or "array":
jbe@138 510 if (lua_getmetatable(L, -1)) {
jbe@144 511 json_regfetch(L, objectmt);
jbe@138 512 if (lua_rawequal(L, -2, -1)) {
jbe@146 513 // if value has metatable for JSON objects,
jbe@138 514 // return string "object":
jbe@138 515 lua_pushliteral(L, "object");
jbe@138 516 return 1;
jbe@138 517 }
jbe@144 518 json_regfetch(L, arraymt);
jbe@138 519 if (lua_rawequal(L, -3, -1)) {
jbe@146 520 // if value has metatable for JSON arrays,
jbe@146 521 // return string "object":
jbe@138 522 lua_pushliteral(L, "array");
jbe@138 523 return 1;
jbe@138 524 }
jbe@146 525 // remove 3 metatables (one of the value, two for comparison) from stack:
jbe@138 526 lua_pop(L, 3);
jbe@138 527 }
jbe@138 528 // otherwise, get the Lua type:
jbe@138 529 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
jbe@126 530 }
jbe@126 531 }
jbe@137 532 // return the top most value on the Lua stack:
jbe@137 533 return 1;
jbe@130 534 }
jbe@130 535
jbe@147 536 // gets a value from a JSON document (passed as first argument)
jbe@147 537 // using a path (passed as variable number of keys after first argument):
jbe@130 538 static int json_get(lua_State *L) {
jbe@137 539 return json_path(L, 0);
jbe@130 540 }
jbe@130 541
jbe@147 542 // gets a value's type from a JSON document (passed as first argument)
jbe@147 543 // using a path (variable number of keys after first argument):
jbe@130 544 static int json_type(lua_State *L) {
jbe@137 545 return json_path(L, 1);
jbe@130 546 }
jbe@130 547
jbe@147 548 // returns the length of a JSON array (or zero for a table without numeric keys):
jbe@130 549 static int json_len(lua_State *L) {
jbe@147 550 // stack shall contain one function argument:
jbe@130 551 lua_settop(L, 1);
jbe@148 552 // try to get corresponding shadow table for first argument:
jbe@144 553 json_regfetch(L, shadowtbl);
jbe@130 554 lua_pushvalue(L, 1);
jbe@138 555 lua_rawget(L, -2);
jbe@147 556 // if shadow table does not exist, return length of argument, else length of shadow table:
jbe@147 557 lua_pushnumber(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
jbe@123 558 return 1;
jbe@123 559 }
jbe@123 560
jbe@130 561 static int json_index(lua_State *L) {
jbe@148 562 // stack shall contain two function arguments:
jbe@130 563 lua_settop(L, 2);
jbe@155 564 // get corresponding shadow table for first argument:
jbe@144 565 json_regfetch(L, shadowtbl);
jbe@130 566 lua_pushvalue(L, 1);
jbe@155 567 lua_rawget(L, -2);
jbe@148 568 // throw error if no shadow table was found:
jbe@139 569 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@148 570 // use key passed as second argument to lookup value in shadow table:
jbe@130 571 lua_pushvalue(L, 2);
jbe@130 572 lua_rawget(L, -2);
jbe@148 573 // if value is null-marker, then push nil onto stack:
jbe@155 574 if (json_isnullmark(L, -1)) lua_pushnil(L);
jbe@148 575 // return either looked up value, or nil
jbe@127 576 return 1;
jbe@127 577 }
jbe@127 578
jbe@130 579 static int json_newindex(lua_State *L) {
jbe@148 580 // stack shall contain three function arguments:
jbe@130 581 lua_settop(L, 3);
jbe@148 582 // get corresponding shadow table for first argument:
jbe@144 583 json_regfetch(L, shadowtbl);
jbe@123 584 lua_pushvalue(L, 1);
jbe@143 585 lua_rawget(L, -2);
jbe@148 586 // throw error if no shadow table was found:
jbe@130 587 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@148 588 // replace first argument with shadow table:
jbe@130 589 lua_replace(L, 1);
jbe@148 590 // reset stack and use second and third argument to write to shadow table:
jbe@139 591 lua_settop(L, 3);
jbe@130 592 lua_rawset(L, 1);
jbe@148 593 // return nothing:
jbe@148 594 return 0;
jbe@121 595 }
jbe@121 596
jbe@135 597 static int json_pairs_iterfunc(lua_State *L) {
jbe@149 598 // stack shall contain two function arguments:
jbe@135 599 lua_settop(L, 2);
jbe@155 600 // get corresponding shadow table for first argument:
jbe@144 601 json_regfetch(L, shadowtbl);
jbe@135 602 lua_pushvalue(L, 1);
jbe@155 603 lua_rawget(L, -2);
jbe@149 604 // throw error if no shadow table was found:
jbe@135 605 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@149 606 // get next key value pair from shadow table (using previous key from argument 2)
jbe@149 607 // and return nothing if there is no next pair:
jbe@135 608 lua_pushvalue(L, 2);
jbe@135 609 if (!lua_next(L, -2)) return 0;
jbe@149 610 // replace null-marker with nil:
jbe@155 611 if (json_isnullmark(L, -1)) {
jbe@135 612 lua_pop(L, 1);
jbe@135 613 lua_pushnil(L);
jbe@135 614 }
jbe@149 615 // return key and value (or key and nil, if null-marker was found):
jbe@135 616 return 2;
jbe@135 617 }
jbe@135 618
jbe@149 619 // returns a triple such that 'for key, value in pairs(obj) do ... end'
jbe@149 620 // iterates through all key value pairs (including JSON null keys represented as Lua nil):
jbe@135 621 static int json_pairs(lua_State *L) {
jbe@149 622 // return triple of function json_pairs_iterfunc, first argument, and nil:
jbe@139 623 lua_pushcfunction(L, json_pairs_iterfunc);
jbe@135 624 lua_pushvalue(L, 1);
jbe@135 625 lua_pushnil(L);
jbe@135 626 return 3;
jbe@135 627 }
jbe@135 628
jbe@134 629 static int json_ipairs_iterfunc(lua_State *L) {
jbe@152 630 lua_Integer idx;
jbe@149 631 // stack shall contain two function arguments:
jbe@134 632 lua_settop(L, 2);
jbe@149 633 // calculate new index by incrementing second argument:
jbe@134 634 idx = lua_tointeger(L, 2) + 1;
jbe@149 635 // get corresponding shadow table for first argument:
jbe@155 636 json_regfetch(L, shadowtbl);
jbe@134 637 lua_pushvalue(L, 1);
jbe@155 638 lua_rawget(L, -2);
jbe@149 639 // throw error if no shadow table was found:
jbe@134 640 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@149 641 // do integer lookup in shadow table:
jbe@134 642 lua_rawgeti(L, -1, idx);
jbe@149 643 // return nothing if there was no value:
jbe@134 644 if (lua_isnil(L, -1)) return 0;
jbe@149 645 // return new index and
jbe@149 646 // either the looked up value if it is not equal to the null-marker
jbe@149 647 // or nil instead of null-marker:
jbe@134 648 lua_pushinteger(L, idx);
jbe@155 649 if (json_isnullmark(L, -2)) lua_pushnil(L);
jbe@134 650 else lua_pushvalue(L, -2);
jbe@134 651 return 2;
jbe@134 652 }
jbe@134 653
jbe@149 654 // returns a triple such that 'for idx, value in ipairs(ary) do ... end'
jbe@149 655 // iterates through all values (including JSON null represented as Lua nil):
jbe@134 656 static int json_ipairs(lua_State *L) {
jbe@149 657 // return triple of function json_ipairs_iterfunc, first argument, and zero:
jbe@139 658 lua_pushcfunction(L, json_ipairs_iterfunc);
jbe@134 659 lua_pushvalue(L, 1);
jbe@134 660 lua_pushinteger(L, 0);
jbe@134 661 return 3;
jbe@134 662 }
jbe@134 663
jbe@154 664 #define JSON_TABLETYPE_UNKNOWN 0
jbe@154 665 #define JSON_TABLETYPE_OBJECT 1
jbe@154 666 #define JSON_TABLETYPE_ARRAY 2
jbe@154 667
jbe@154 668 static int json_export(lua_State *L) {
jbe@154 669 lua_Number num;
jbe@154 670 const char *str;
jbe@154 671 unsigned char c;
jbe@154 672 size_t strlen;
jbe@154 673 size_t pos = 0;
jbe@154 674 luaL_Buffer buf;
jbe@154 675 char hexcode[7]; // backslash, character 'u', 4 hex digits, and terminating NULL byte
jbe@154 676 int luatype;
jbe@154 677 int tabletype = JSON_TABLETYPE_UNKNOWN;
jbe@154 678 int needsep = 0;
jbe@154 679 lua_Integer idx;
jbe@154 680 lua_settop(L, 1);
jbe@157 681 if (json_isnullmark(L, 1)) {
jbe@157 682 lua_pushnil(L);
jbe@157 683 lua_replace(L, 1);
jbe@157 684 }
jbe@154 685 switch (lua_type(L, 1)) {
jbe@154 686 case LUA_TNIL:
jbe@154 687 lua_pushliteral(L, "null");
jbe@154 688 return 1;
jbe@154 689 case LUA_TNUMBER:
jbe@154 690 num = lua_tonumber(L, 1);
jbe@154 691 if (isnan(num)) return luaL_error(L, "JSON export not possible for NaN value");
jbe@154 692 if (isinf(num)) return luaL_error(L, "JSON export not possible for infinite numbers");
jbe@154 693 lua_tostring(L, 1);
jbe@154 694 return 1;
jbe@154 695 case LUA_TBOOLEAN:
jbe@154 696 if (lua_toboolean(L, 1)) lua_pushliteral(L, "true");
jbe@154 697 else lua_pushliteral(L, "false");
jbe@154 698 return 1;
jbe@154 699 case LUA_TSTRING:
jbe@154 700 str = lua_tolstring(L, 1, &strlen);
jbe@154 701 luaL_buffinit(L, &buf);
jbe@154 702 luaL_addchar(&buf, '"');
jbe@154 703 while (pos < strlen) {
jbe@154 704 c = str[pos++];
jbe@154 705 if (c == '"') luaL_addstring(&buf, "\\\"");
jbe@154 706 else if (c == '\\') luaL_addstring(&buf, "\\\\");
jbe@154 707 else if (c == 127) luaL_addstring(&buf, "\\u007F");
jbe@154 708 else if (c >= 32) luaL_addchar(&buf, c);
jbe@154 709 else if (c == '\b') luaL_addstring(&buf, "\\b");
jbe@154 710 else if (c == '\f') luaL_addstring(&buf, "\\f");
jbe@154 711 else if (c == '\n') luaL_addstring(&buf, "\\n");
jbe@154 712 else if (c == '\r') luaL_addstring(&buf, "\\r");
jbe@154 713 else if (c == '\t') luaL_addstring(&buf, "\\t");
jbe@154 714 else if (c == '\v') luaL_addstring(&buf, "\\v");
jbe@154 715 else {
jbe@154 716 sprintf(hexcode, "\\u%04X", c);
jbe@154 717 luaL_addstring(&buf, hexcode);
jbe@154 718 }
jbe@154 719 }
jbe@154 720 luaL_addchar(&buf, '"');
jbe@154 721 luaL_pushresult(&buf);
jbe@154 722 return 1;
jbe@154 723 case LUA_TTABLE:
jbe@154 724 if (lua_getmetatable(L, 1)) {
jbe@154 725 json_regfetch(L, objectmt);
jbe@154 726 if (lua_rawequal(L, -2, -1)) {
jbe@154 727 tabletype = JSON_TABLETYPE_OBJECT;
jbe@154 728 } else {
jbe@154 729 json_regfetch(L, arraymt);
jbe@154 730 if (lua_rawequal(L, -3, -1)) tabletype = JSON_TABLETYPE_ARRAY;
jbe@154 731 }
jbe@154 732 }
jbe@154 733 json_regfetch(L, shadowtbl);
jbe@154 734 lua_pushvalue(L, 1);
jbe@154 735 lua_rawget(L, -2);
jbe@154 736 if (!lua_isnil(L, -1)) lua_replace(L, 1);
jbe@154 737 lua_settop(L, 1);
jbe@154 738 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
jbe@154 739 for (lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
jbe@154 740 luatype = lua_type(L, -2);
jbe@154 741 if (tabletype == JSON_TABLETYPE_UNKNOWN) {
jbe@154 742 if (luatype == LUA_TSTRING) tabletype = JSON_TABLETYPE_OBJECT;
jbe@154 743 else if (luatype == LUA_TNUMBER) tabletype = JSON_TABLETYPE_ARRAY;
jbe@154 744 } else if (
jbe@154 745 (tabletype == JSON_TABLETYPE_OBJECT && luatype == LUA_TNUMBER) ||
jbe@154 746 (tabletype == JSON_TABLETYPE_ARRAY && luatype == LUA_TSTRING)
jbe@154 747 ) {
jbe@154 748 goto json_export_tabletype_error;
jbe@154 749 }
jbe@154 750 }
jbe@154 751 }
jbe@154 752 switch (tabletype) {
jbe@154 753 case JSON_TABLETYPE_OBJECT:
jbe@154 754 lua_settop(L, 3);
jbe@154 755 luaL_buffinit(L, &buf);
jbe@154 756 luaL_addchar(&buf, '{');
jbe@154 757 for (lua_pushnil(L); lua_next(L, 1); ) {
jbe@154 758 if (lua_type(L, -2) == LUA_TSTRING) {
jbe@154 759 lua_replace(L, 3);
jbe@154 760 lua_replace(L, 2);
jbe@154 761 if (needsep) luaL_addchar(&buf, ',');
jbe@154 762 else needsep = 1;
jbe@154 763 lua_pushcfunction(L, json_export);
jbe@154 764 lua_pushvalue(L, 2);
jbe@154 765 lua_call(L, 1, 1);
jbe@154 766 luaL_addvalue(&buf);
jbe@154 767 luaL_addchar(&buf, ':');
jbe@155 768 if (json_isnullmark(L, 3)) {
jbe@154 769 luaL_addstring(&buf, "null");
jbe@154 770 } else {
jbe@154 771 lua_pushcfunction(L, json_export);
jbe@154 772 lua_pushvalue(L, 3);
jbe@154 773 lua_call(L, 1, 1);
jbe@154 774 luaL_addvalue(&buf);
jbe@154 775 }
jbe@154 776 lua_pushvalue(L, 2);
jbe@154 777 } else {
jbe@154 778 lua_pop(L, 1);
jbe@154 779 }
jbe@154 780 }
jbe@154 781 luaL_addchar(&buf, '}');
jbe@154 782 luaL_pushresult(&buf);
jbe@154 783 return 1;
jbe@154 784 case JSON_TABLETYPE_ARRAY:
jbe@154 785 lua_settop(L, 2);
jbe@154 786 luaL_buffinit(L, &buf);
jbe@154 787 luaL_addchar(&buf, '[');
jbe@154 788 for (idx = 1; ; idx++) {
jbe@154 789 lua_rawgeti(L, 1, idx);
jbe@154 790 if (lua_isnil(L, -1)) {
jbe@154 791 lua_pop(L, 1);
jbe@154 792 break;
jbe@154 793 }
jbe@154 794 lua_replace(L, 2);
jbe@154 795 if (needsep) luaL_addchar(&buf, ',');
jbe@154 796 else needsep = 1;
jbe@154 797 lua_pushcfunction(L, json_export);
jbe@154 798 lua_pushvalue(L, 2);
jbe@154 799 lua_call(L, 1, 1);
jbe@154 800 luaL_addvalue(&buf);
jbe@154 801 }
jbe@154 802 luaL_addchar(&buf, ']');
jbe@154 803 luaL_pushresult(&buf);
jbe@154 804 return 1;
jbe@154 805 }
jbe@154 806 json_export_tabletype_error:
jbe@154 807 return luaL_error(L, "JSON export not possible for ambiguous table (cannot decide whether it is an object or array)");
jbe@154 808 }
jbe@154 809 return luaL_error(L, "JSON export not possible for values of type \"%s\"", lua_typename(L, lua_type(L, 1)));
jbe@154 810 }
jbe@154 811
jbe@149 812 // functions in library module:
jbe@121 813 static const struct luaL_Reg json_module_functions[] = {
jbe@133 814 {"object", json_object},
jbe@133 815 {"array", json_array},
jbe@121 816 {"import", json_import},
jbe@154 817 {"export", json_export},
jbe@130 818 {"get", json_get},
jbe@127 819 {"type", json_type},
jbe@121 820 {NULL, NULL}
jbe@121 821 };
jbe@121 822
jbe@149 823 // metamethods for JSON objects, JSON arrays, and unknown JSON collections (object or array):
jbe@126 824 static const struct luaL_Reg json_metatable_functions[] = {
jbe@130 825 {"__len", json_len},
jbe@130 826 {"__index", json_index},
jbe@130 827 {"__newindex", json_newindex},
jbe@135 828 {"__pairs", json_pairs},
jbe@134 829 {"__ipairs", json_ipairs},
jbe@160 830 {"__tostring", json_export},
jbe@126 831 {NULL, NULL}
jbe@126 832 };
jbe@126 833
jbe@157 834 // metamethods for JSON null marker:
jbe@157 835 static const struct luaL_Reg json_nullmark_metamethods[] = {
jbe@157 836 {"__tostring", json_nullmark_tostring},
jbe@157 837 {NULL, NULL}
jbe@157 838 };
jbe@157 839
jbe@149 840 // initializes json library:
jbe@121 841 int luaopen_json(lua_State *L) {
jbe@149 842 // empty stack:
jbe@126 843 lua_settop(L, 0);
jbe@149 844 // push library module onto stack position 1:
jbe@149 845 lua_newtable(L);
jbe@149 846 // register library functions:
jbe@149 847 luaL_setfuncs(L, json_module_functions, 0);
jbe@149 848 // create and store objectmt:
jbe@138 849 lua_newtable(L);
jbe@138 850 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 851 json_regstore(L, objectmt);
jbe@149 852 // create and store arraymt:
jbe@138 853 lua_newtable(L);
jbe@138 854 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 855 json_regstore(L, arraymt);
jbe@149 856 // create and store ephemeron table to store shadow tables for each JSON object/array
jbe@149 857 // to allow NULL values returned as nil
jbe@149 858 lua_newtable(L);
jbe@138 859 lua_newtable(L); // metatable for ephemeron table
jbe@121 860 lua_pushliteral(L, "__mode");
jbe@121 861 lua_pushliteral(L, "k");
jbe@138 862 lua_rawset(L, -3);
jbe@138 863 lua_setmetatable(L, -2);
jbe@144 864 json_regstore(L, shadowtbl);
jbe@157 865 // set metatable of null marker and make it available through library module:
jbe@157 866 json_pushnullmark(L);
jbe@157 867 lua_newtable(L);
jbe@157 868 luaL_setfuncs(L, json_nullmark_metamethods, 0);
jbe@157 869 lua_setmetatable(L, -2);
jbe@157 870 lua_setfield(L, 1, "null");
jbe@157 871 // return library module (that's expected on top of stack):
jbe@121 872 return 1;
jbe@121 873 }

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