webmcp

annotate libraries/json/json.c @ 145:0edc2f05c66a

find changesets by author, revision, files, or words in the commit message
Use lightuserdata directly to store JSON null values in JSON library
author jbe
date Wed Jul 30 19:59:11 2014 +0200 (2014-07-30)
parents 0690fe79b673
children 7912a05ebc3f
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@121 5
jbe@144 6 // maximum number of nested JSON values (objects and arrays):
jbe@142 7 #define JSON_MAXDEPTH 100
jbe@142 8
jbe@144 9 // macros for usage of Lua registry:
jbe@144 10 #define JSON_REGENT char
jbe@145 11 #define JSON_REGPOINTER void *
jbe@145 12 #define json_pushlightref(L, x) (lua_pushlightuserdata((L), &json_reference.x))
jbe@145 13 #define json_regpointer(x) (&json_registry.x)
jbe@145 14 #define json_regfetchpointer(L, x) (lua_pushlightuserdata((L), (x)), lua_rawget((L), LUA_REGISTRYINDEX))
jbe@145 15 #define json_regfetch(L, x) (json_regfetchpointer(L, json_regpointer(x)))
jbe@145 16 #define json_regstore(L, x) (lua_pushlightuserdata(L, json_regpointer(x)), lua_pushvalue(L, -2), lua_rawset(L, LUA_REGISTRYINDEX));
jbe@145 17
jbe@145 18 // generate dummy memory addresses that represent Lua objects
jbe@145 19 // directly via lightuserdata values (not using the Lua registry):
jbe@145 20 static struct {
jbe@145 21 JSON_REGENT nullmark; // magic value to indicate JSON null value
jbe@145 22 } json_reference;
jbe@145 23
jbe@138 24
jbe@144 25 // generate dummy memory addresses that represent Lua objects
jbe@145 26 // via lightuserdata keys and LUA_REGISTRYINDEX:
jbe@144 27 static struct {
jbe@145 28 JSON_REGENT shadowtbl; // ephemeron table that maps tables to their corresponding shadow table
jbe@145 29 JSON_REGENT unknownmt; // metatable for tables that may be either JSON objects or JSON arrays
jbe@145 30 JSON_REGENT objectmt; // metatable for JSON objects
jbe@145 31 JSON_REGENT arraymt; // metatable for JSON arrays
jbe@144 32 } json_registry;
jbe@138 33
jbe@145 34 // marks a Lua table as JSON object or JSON array:
jbe@136 35 // (returns its modified argument or a new table if argument is nil)
jbe@145 36 static int json_mark(lua_State *L, JSON_REGPOINTER mt) {
jbe@145 37 // check if argument is nil
jbe@136 38 if (lua_isnoneornil(L, 1)) {
jbe@145 39 // create new table at stack position 1:
jbe@136 40 lua_settop(L, 0);
jbe@136 41 lua_newtable(L);
jbe@145 42 // create shadow table (leaving previously created table on stack position 1):
jbe@144 43 json_regfetch(L, shadowtbl);
jbe@136 44 lua_pushvalue(L, 1);
jbe@136 45 lua_newtable(L);
jbe@143 46 lua_rawset(L, -3);
jbe@143 47 } else {
jbe@145 48 // push shadow table on top of stack:
jbe@144 49 json_regfetch(L, shadowtbl);
jbe@143 50 lua_pushvalue(L, 1);
jbe@143 51 lua_rawget(L, -2);
jbe@145 52 // if shadow table does not exist:
jbe@143 53 if (lua_isnil(L, -1)) {
jbe@145 54 // create shadow table and leave it on top of stack:
jbe@143 55 lua_newtable(L);
jbe@143 56 lua_pushvalue(L, 1);
jbe@143 57 lua_pushvalue(L, -2);
jbe@143 58 lua_rawset(L, -5);
jbe@143 59 }
jbe@145 60 // move elements from original table to shadow table (that's expected on top of stack):
jbe@143 61 for(lua_pushnil(L); lua_next(L, 1); lua_pop(L, 1)) {
jbe@143 62 lua_pushvalue(L, -2);
jbe@143 63 lua_pushnil(L);
jbe@143 64 lua_rawset(L, 1);
jbe@143 65 lua_pushvalue(L, -2);
jbe@143 66 lua_pushvalue(L, -2);
jbe@143 67 lua_rawset(L, -5);
jbe@143 68 }
jbe@136 69 }
jbe@138 70 // discard everything but table to return:
jbe@138 71 lua_settop(L, 1);
jbe@136 72 // set metatable:
jbe@145 73 json_regfetchpointer(L, mt);
jbe@136 74 lua_setmetatable(L, 1);
jbe@138 75 // return table:
jbe@136 76 return 1;
jbe@136 77 }
jbe@136 78
jbe@136 79 // marks a table as JSON object:
jbe@136 80 // (returns its modified argument or a new table if argument is nil)
jbe@136 81 static int json_object(lua_State *L) {
jbe@145 82 return json_mark(L, json_regpointer(objectmt));
jbe@136 83 }
jbe@136 84
jbe@136 85 // marks a table as JSON array:
jbe@136 86 // (returns its modified argument or a new table if argument is nil)
jbe@136 87 static int json_array(lua_State *L) {
jbe@145 88 return json_mark(L, json_regpointer(arraymt));
jbe@136 89 }
jbe@136 90
jbe@145 91 // internal states of JSON parser:
jbe@124 92 #define JSON_STATE_VALUE 0
jbe@124 93 #define JSON_STATE_OBJECT_KEY 1
jbe@124 94 #define JSON_STATE_OBJECT_KEY_TERMINATOR 2
jbe@124 95 #define JSON_STATE_OBJECT_VALUE 3
jbe@124 96 #define JSON_STATE_OBJECT_SEPARATOR 4
jbe@124 97 #define JSON_STATE_ARRAY_VALUE 5
jbe@124 98 #define JSON_STATE_ARRAY_SEPARATOR 6
jbe@124 99 #define JSON_STATE_END 7
jbe@121 100
jbe@145 101 // special Lua stack indicies for json_import function:
jbe@138 102 #define json_import_objectmt_idx 2
jbe@138 103 #define json_import_arraymt_idx 3
jbe@138 104 #define json_import_shadowtbl_idx 4
jbe@138 105 #define json_import_nullmark_idx 5
jbe@138 106
jbe@136 107 // decodes a JSON document:
jbe@121 108 static int json_import(lua_State *L) {
jbe@136 109 const char *str; // string to parse
jbe@136 110 size_t total; // total length of string to parse
jbe@136 111 size_t pos = 0; // current position in string to parse
jbe@136 112 size_t level = 0; // nested levels of objects/arrays currently being processed
jbe@145 113 int mode = JSON_STATE_VALUE; // state of parser (i.e. "what's expected next?")
jbe@136 114 char c; // variable to store a single character to be processed
jbe@145 115 luaL_Buffer luabuf; // Lua buffer to decode JSON string values
jbe@145 116 char *cbuf; // C buffer to decode JSON string values
jbe@136 117 size_t writepos; // write position of decoded strings in C buffer
jbe@145 118 // stack shall only contain one function argument:
jbe@138 119 lua_settop(L, 1);
jbe@145 120 // push objectmt on stack position 2:
jbe@144 121 json_regfetch(L, objectmt);
jbe@145 122 // push arraymt on stack position 3:
jbe@144 123 json_regfetch(L, arraymt);
jbe@145 124 // push shadowtbl on stack position 4:
jbe@144 125 json_regfetch(L, shadowtbl);
jbe@145 126 // push nullmark on stack position 5:
jbe@145 127 json_pushlightref(L, nullmark);
jbe@136 128 // require string as first argument:
jbe@136 129 str = luaL_checklstring(L, 1, &total);
jbe@136 130 // if string contains a NULL byte, this is a syntax error
jbe@136 131 if (strlen(str) != total) goto json_import_syntax_error;
jbe@136 132 // main loop of parser:
jbe@136 133 json_import_loop:
jbe@136 134 // skip whitespace and store next character in variable 'c':
jbe@121 135 while (c = str[pos], c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\f') pos++;
jbe@136 136 // switch statement to handle certain (single) characters:
jbe@121 137 switch (c) {
jbe@136 138 // handle end of JSON document:
jbe@121 139 case 0:
jbe@136 140 // if end of JSON document was expected, then return top element of stack as result:
jbe@124 141 if (mode == JSON_STATE_END) return 1;
jbe@136 142 // otherwise, the JSON document was malformed:
jbe@121 143 json_import_unexpected_eof:
jbe@121 144 lua_pushnil(L);
jbe@121 145 if (level == 0) lua_pushliteral(L, "Empty string");
jbe@121 146 else lua_pushliteral(L, "Unexpected end of JSON document");
jbe@121 147 return 2;
jbe@136 148 // new JSON object:
jbe@121 149 case '{':
jbe@136 150 // if a JSON object is not expected here, then return an error:
jbe@124 151 if (mode != JSON_STATE_VALUE && mode != JSON_STATE_OBJECT_VALUE && mode != JSON_STATE_ARRAY_VALUE)
jbe@121 152 goto json_import_syntax_error;
jbe@136 153 // create JSON object on stack:
jbe@136 154 lua_newtable(L);
jbe@136 155 // set metatable of JSON object:
jbe@138 156 lua_pushvalue(L, json_import_objectmt_idx);
jbe@125 157 lua_setmetatable(L, -2);
jbe@136 158 // create internal shadow table on stack:
jbe@136 159 lua_newtable(L);
jbe@138 160 // register internal shadow table (and cleanup stack afterwards):
jbe@123 161 lua_pushvalue(L, -2);
jbe@123 162 lua_pushvalue(L, -2);
jbe@138 163 lua_rawset(L, json_import_shadowtbl_idx);
jbe@136 164 // expect object key (or end of object) and continue with loop:
jbe@136 165 mode = JSON_STATE_OBJECT_KEY;
jbe@142 166 goto json_import_open;
jbe@136 167 // new JSON array:
jbe@121 168 case '[':
jbe@136 169 // if a JSON array is not expected here, then return an error:
jbe@124 170 if (mode != JSON_STATE_VALUE && mode != JSON_STATE_OBJECT_VALUE && mode != JSON_STATE_ARRAY_VALUE)
jbe@121 171 goto json_import_syntax_error;
jbe@136 172 // create JSON array on stack:
jbe@136 173 lua_newtable(L);
jbe@136 174 // set metatable of JSON array:
jbe@138 175 lua_pushvalue(L, json_import_arraymt_idx);
jbe@125 176 lua_setmetatable(L, -2);
jbe@136 177 // create internal shadow table on stack:
jbe@136 178 lua_newtable(L);
jbe@138 179 // register internal shadow table (and cleanup stack afterwards):
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@140 183 // add nil as key (needed to keep stack balance) and as magic to detect arrays:
jbe@140 184 lua_pushnil(L);
jbe@142 185 // expect array value (or end of array) and continue with loop:
jbe@142 186 mode = JSON_STATE_ARRAY_VALUE;
jbe@142 187 // continue with common code for opening JSON object and JSON array:
jbe@142 188 // commn code for opening JSON object or JSON array:
jbe@142 189 json_import_open:
jbe@142 190 // limit nested levels:
jbe@142 191 if (level >= JSON_MAXDEPTH) {
jbe@142 192 lua_pushnil(L);
jbe@142 193 lua_pushliteral(L, "Too many nested JSON levels");
jbe@142 194 return 2;
jbe@142 195 }
jbe@142 196 // additional buffer overflow protection:
jbe@142 197 if (!lua_checkstack(L, LUA_MINSTACK))
jbe@142 198 return luaL_error(L, "Caught stack overflow in JSON import function (too many nested levels and stack size too small)");
jbe@136 199 // increment level:
jbe@121 200 level++;
jbe@142 201 // consume input character:
jbe@142 202 pos++;
jbe@121 203 goto json_import_loop;
jbe@136 204 // end of JSON object:
jbe@121 205 case '}':
jbe@136 206 // if end of JSON object is not expected here, then return an error:
jbe@124 207 if (mode != JSON_STATE_OBJECT_KEY && mode != JSON_STATE_OBJECT_SEPARATOR)
jbe@121 208 goto json_import_syntax_error;
jbe@136 209 // jump to common code for end of JSON object and JSON array:
jbe@121 210 goto json_import_close;
jbe@136 211 // end of JSON array:
jbe@121 212 case ']':
jbe@136 213 // if end of JSON array is not expected here, then return an error:
jbe@124 214 if (mode != JSON_STATE_ARRAY_VALUE && mode != JSON_STATE_ARRAY_SEPARATOR)
jbe@121 215 goto json_import_syntax_error;
jbe@140 216 // pop nil key/magic:
jbe@140 217 lua_pop(L, 1);
jbe@136 218 // continue with common code for end of JSON object and JSON array:
jbe@136 219 // common code for end of JSON object or JSON array:
jbe@121 220 json_import_close:
jbe@136 221 // consume input character:
jbe@121 222 pos++;
jbe@136 223 // pop shadow table:
jbe@136 224 lua_pop(L, 1);
jbe@136 225 // check if nested:
jbe@121 226 if (--level) {
jbe@136 227 // if nested, then check if outer(!) structure is an array or object:
jbe@140 228 if (lua_isnil(L, -2)) {
jbe@136 229 // select array value processing:
jbe@124 230 mode = JSON_STATE_ARRAY_VALUE;
jbe@121 231 } else {
jbe@136 232 // select object value processing:
jbe@124 233 mode = JSON_STATE_OBJECT_VALUE;
jbe@121 234 }
jbe@136 235 // store value in outer structure:
jbe@121 236 goto json_import_process_value;
jbe@121 237 }
jbe@136 238 // if not nested, then expect end of JSON document and continue with loop:
jbe@136 239 mode = JSON_STATE_END;
jbe@121 240 goto json_import_loop;
jbe@136 241 // key terminator:
jbe@121 242 case ':':
jbe@136 243 // if key terminator is not expected here, then return an error:
jbe@124 244 if (mode != JSON_STATE_OBJECT_KEY_TERMINATOR)
jbe@121 245 goto json_import_syntax_error;
jbe@136 246 // consume input character:
jbe@121 247 pos++;
jbe@136 248 // set state of parser and continue with loop:
jbe@124 249 mode = JSON_STATE_OBJECT_VALUE;
jbe@121 250 goto json_import_loop;
jbe@136 251 // value terminator (NOTE: trailing comma at end of value or key-value list is tolerated by this parser)
jbe@121 252 case ',':
jbe@136 253 // change parser state accordingly:
jbe@124 254 if (mode == JSON_STATE_OBJECT_SEPARATOR) {
jbe@124 255 mode = JSON_STATE_OBJECT_KEY;
jbe@124 256 } else if (mode == JSON_STATE_ARRAY_SEPARATOR) {
jbe@124 257 mode = JSON_STATE_ARRAY_VALUE;
jbe@121 258 } else {
jbe@136 259 // if value terminator is not expected here, then return an error:
jbe@136 260 goto json_import_syntax_error;
jbe@121 261 }
jbe@136 262 // consume input character:
jbe@121 263 pos++;
jbe@136 264 // continue with loop:
jbe@121 265 goto json_import_loop;
jbe@136 266 // string literal:
jbe@121 267 case '"':
jbe@136 268 // prepare buffer to decode string (with maximum possible length) and set write position to zero:
jbe@121 269 cbuf = luaL_buffinitsize(L, &luabuf, total-pos);
jbe@121 270 writepos = 0;
jbe@136 271 // consume quote character:
jbe@121 272 pos++;
jbe@136 273 // read next character until encountering end quote:
jbe@121 274 while ((c = str[pos++]) != '"') {
jbe@121 275 if (c == 0) {
jbe@136 276 // handle unexpected end-of-string:
jbe@121 277 goto json_import_unexpected_eof;
jbe@121 278 } else if (c < 32 || c == 127) {
jbe@136 279 // do not allow ASCII control characters:
jbe@136 280 // NOTE: illegal UTF-8 sequences and extended control characters are not sanitized
jbe@136 281 // by this parser to allow different encodings than Unicode
jbe@121 282 lua_pushnil(L);
jbe@121 283 lua_pushliteral(L, "Unexpected control character in JSON string");
jbe@121 284 return 2;
jbe@121 285 } else if (c == '\\') {
jbe@136 286 // read next char after backslash escape:
jbe@121 287 c = str[pos++];
jbe@121 288 switch (c) {
jbe@136 289 // unexpected end-of-string:
jbe@121 290 case 0:
jbe@121 291 goto json_import_unexpected_eof;
jbe@136 292 // unescaping of quotation mark, slash, and backslash:
jbe@121 293 case '"':
jbe@121 294 case '/':
jbe@121 295 case '\\':
jbe@121 296 cbuf[writepos++] = c;
jbe@121 297 break;
jbe@136 298 // unescaping of backspace:
jbe@121 299 case 'b':
jbe@121 300 cbuf[writepos++] = '\b';
jbe@121 301 break;
jbe@136 302 // unescaping of form-feed:
jbe@121 303 case 'f':
jbe@121 304 cbuf[writepos++] = '\f';
jbe@121 305 break;
jbe@136 306 // unescaping of new-line:
jbe@121 307 case 'n':
jbe@121 308 cbuf[writepos++] = '\n';
jbe@121 309 break;
jbe@136 310 // unescaping of carriage-return:
jbe@121 311 case 'r':
jbe@121 312 cbuf[writepos++] = '\r';
jbe@121 313 break;
jbe@136 314 // unescaping of tabulator:
jbe@121 315 case 't':
jbe@121 316 cbuf[writepos++] = '\t';
jbe@121 317 break;
jbe@136 318 // unescaping of UTF-16 characters
jbe@121 319 case 'u':
jbe@121 320 lua_pushnil(L);
jbe@121 321 lua_pushliteral(L, "JSON unicode escape sequences are not implemented yet"); // TODO
jbe@121 322 return 2;
jbe@136 323 // unexpected escape sequence:
jbe@121 324 default:
jbe@121 325 lua_pushnil(L);
jbe@121 326 lua_pushliteral(L, "Unexpected string escape sequence in JSON document");
jbe@121 327 return 2;
jbe@121 328 }
jbe@121 329 } else {
jbe@136 330 // normal character:
jbe@121 331 cbuf[writepos++] = c;
jbe@121 332 }
jbe@121 333 }
jbe@136 334 // process buffer to Lua string:
jbe@121 335 luaL_pushresultsize(&luabuf, writepos);
jbe@136 336 // continue with processing of decoded string:
jbe@121 337 goto json_import_process_value;
jbe@121 338 }
jbe@136 339 // process values whose type is is not deducible from a single character:
jbe@136 340 if ((c >= '0' && c <= '9') || c == '-' || c == '+') {
jbe@136 341 // numbers:
jbe@122 342 char *endptr;
jbe@122 343 double numval;
jbe@122 344 numval = strtod(str+pos, &endptr);
jbe@122 345 if (endptr == str+pos) goto json_import_syntax_error;
jbe@122 346 pos += endptr - (str+pos);
jbe@122 347 lua_pushnumber(L, numval);
jbe@122 348 } else if (!strncmp(str+pos, "true", 4)) {
jbe@136 349 // consume 4 input characters for "true":
jbe@121 350 pos += 4;
jbe@136 351 // put Lua true value on stack:
jbe@136 352 lua_pushboolean(L, 1);
jbe@121 353 } else if (!strncmp(str+pos, "false", 5)) {
jbe@136 354 // consume 5 input characters for "false":
jbe@121 355 pos += 5;
jbe@136 356 // put Lua false value on stack:
jbe@136 357 lua_pushboolean(L, 0);
jbe@121 358 } else if (!strncmp(str+pos, "null", 4)) {
jbe@136 359 // consume 4 input characters for "null":
jbe@136 360 pos += 4;
jbe@136 361 // put special null-marker on stack:
jbe@138 362 lua_pushvalue(L, json_import_nullmark_idx);
jbe@121 363 } else {
jbe@136 364 // all other cases are a syntax error:
jbe@121 365 goto json_import_syntax_error;
jbe@121 366 }
jbe@136 367 // process a decoded value or key value pair (expected on top of Lua stack):
jbe@136 368 json_import_process_value:
jbe@121 369 switch (mode) {
jbe@136 370 // an object key has been read:
jbe@124 371 case JSON_STATE_OBJECT_KEY:
jbe@136 372 // if an object key is not a string, then this is a syntax error:
jbe@121 373 if (lua_type(L, -1) != LUA_TSTRING) goto json_import_syntax_error;
jbe@136 374 // expect key terminator and continue with loop:
jbe@124 375 mode = JSON_STATE_OBJECT_KEY_TERMINATOR;
jbe@121 376 goto json_import_loop;
jbe@136 377 // a key value pair has been read:
jbe@124 378 case JSON_STATE_OBJECT_VALUE:
jbe@136 379 // store key value pair in outer shadow table:
jbe@130 380 lua_rawset(L, -3);
jbe@136 381 // expect value terminator (or end of object) and continue with loop:
jbe@124 382 mode = JSON_STATE_OBJECT_SEPARATOR;
jbe@121 383 goto json_import_loop;
jbe@136 384 // an array value has been read:
jbe@124 385 case JSON_STATE_ARRAY_VALUE:
jbe@136 386 // store value in outer shadow table:
jbe@140 387 lua_rawseti(L, -3, lua_rawlen(L, -3) + 1);
jbe@136 388 // expect value terminator (or end of object) and continue with loop:
jbe@124 389 mode = JSON_STATE_ARRAY_SEPARATOR;
jbe@121 390 goto json_import_loop;
jbe@136 391 // a single value has been read:
jbe@124 392 case JSON_STATE_VALUE:
jbe@136 393 // leave value on top of stack, expect end of JSON document, and continue with loop:
jbe@124 394 mode = JSON_STATE_END;
jbe@121 395 goto json_import_loop;
jbe@121 396 }
jbe@136 397 // syntax error handling (only reachable by goto statement):
jbe@136 398 json_import_syntax_error:
jbe@121 399 lua_pushnil(L);
jbe@121 400 lua_pushliteral(L, "Syntax error in JSON document");
jbe@121 401 return 2;
jbe@121 402 }
jbe@121 403
jbe@138 404 #define json_path_shadowtbl_idx 1
jbe@138 405 #define json_path_nullmark_idx 2
jbe@138 406 #define json_path_idxshift 2
jbe@138 407
jbe@137 408 // gets a value or its type from a JSON document (first argument)
jbe@137 409 // optionally using a path (variable number of keys after first argument):
jbe@137 410 static int json_path(lua_State *L, int type_mode) {
jbe@138 411 int stacktop;
jbe@138 412 int idx = 2 + json_path_idxshift;
jbe@138 413 // insert json_shadowtbl on stack at position 1:
jbe@144 414 json_regfetch(L, shadowtbl);
jbe@138 415 lua_insert(L, 1);
jbe@138 416 // insert json_nullmark on stack at position 2:
jbe@145 417 json_pushlightref(L, nullmark);
jbe@138 418 lua_insert(L, 2);
jbe@137 419 // store number of arguments:
jbe@138 420 stacktop = lua_gettop(L);
jbe@137 421 // follow path, starting with first argument as "current value":
jbe@138 422 lua_pushvalue(L, 1 + json_path_idxshift);
jbe@137 423 // process each "path key":
jbe@138 424 while (idx <= stacktop) {
jbe@137 425 // if "current value" is nil, then the path cannot be walked and nil is returned:
jbe@137 426 if (lua_isnil(L, -1)) return 1;
jbe@137 427 // try to get shadow table of "current value":
jbe@130 428 lua_pushvalue(L, -1);
jbe@138 429 lua_rawget(L, json_path_shadowtbl_idx);
jbe@126 430 if (lua_isnil(L, -1)) {
jbe@137 431 // if no shadow table is found,
jbe@137 432 // drop nil from stack:
jbe@126 433 lua_pop(L, 1);
jbe@130 434 if (lua_type(L, -1) == LUA_TTABLE) {
jbe@137 435 // if "current value" is a table,
jbe@137 436 // get "next value" using the "path key":
jbe@130 437 lua_pushvalue(L, idx++);
jbe@130 438 lua_gettable(L, -2);
jbe@130 439 } else {
jbe@137 440 // if "current value" is not a table,
jbe@137 441 // then the path cannot be walked and nil is returned:
jbe@130 442 lua_pushnil(L);
jbe@137 443 return 1;
jbe@130 444 }
jbe@130 445 } else {
jbe@137 446 // if a shadow table is found,
jbe@137 447 // set "current value" to its shadow table:
jbe@130 448 lua_replace(L, -2);
jbe@137 449 // get "next value" using the "path key":
jbe@130 450 lua_pushvalue(L, idx++);
jbe@130 451 lua_rawget(L, -2);
jbe@126 452 }
jbe@137 453 // the "next value" replaces the "current value":
jbe@130 454 lua_replace(L, -2);
jbe@126 455 }
jbe@137 456 if (!type_mode) {
jbe@137 457 // if a value (and not its type) was requested,
jbe@137 458 // check if value is the null-marker, and store nil on top of Lua stack in that case:
jbe@138 459 if (lua_rawequal(L, -1, json_path_nullmark_idx)) lua_pushnil(L);
jbe@137 460 } else {
jbe@137 461 // if the type was requested,
jbe@137 462 // check if value is the null-marker:
jbe@138 463 if (lua_rawequal(L, -1, json_path_nullmark_idx)) {
jbe@137 464 // if yes, store string "null" on top of Lua stack:
jbe@130 465 lua_pushliteral(L, "null");
jbe@137 466 } else {
jbe@137 467 // otherwise,
jbe@138 468 // check if metatable indicates "object" or "array":
jbe@138 469 if (lua_getmetatable(L, -1)) {
jbe@144 470 json_regfetch(L, objectmt);
jbe@138 471 if (lua_rawequal(L, -2, -1)) {
jbe@138 472 // return string "object":
jbe@138 473 lua_pushliteral(L, "object");
jbe@138 474 return 1;
jbe@138 475 }
jbe@144 476 json_regfetch(L, arraymt);
jbe@138 477 if (lua_rawequal(L, -3, -1)) {
jbe@138 478 // return string "array":
jbe@138 479 lua_pushliteral(L, "array");
jbe@138 480 return 1;
jbe@138 481 }
jbe@138 482 lua_pop(L, 3);
jbe@138 483 }
jbe@138 484 // otherwise, get the Lua type:
jbe@138 485 lua_pushstring(L, lua_typename(L, lua_type(L, -1)));
jbe@126 486 }
jbe@126 487 }
jbe@137 488 // return the top most value on the Lua stack:
jbe@137 489 return 1;
jbe@130 490 }
jbe@130 491
jbe@137 492 // gets a value from a JSON document (first argument)
jbe@137 493 // optionally using a path (variable number of keys after first argument):
jbe@130 494 static int json_get(lua_State *L) {
jbe@137 495 return json_path(L, 0);
jbe@130 496 }
jbe@130 497
jbe@137 498 // gets a value's type from a JSON document (first argument)
jbe@137 499 // optionally using a path (variable number of keys after first argument):
jbe@130 500 static int json_type(lua_State *L) {
jbe@137 501 return json_path(L, 1);
jbe@130 502 }
jbe@130 503
jbe@137 504 // checks if a value in a JSON document (first argument) is null:
jbe@130 505 static int json_isnull(lua_State *L) {
jbe@137 506 const char *jsontype;
jbe@138 507 lua_pushcfunction(L, json_type);
jbe@137 508 lua_insert(L, 1);
jbe@137 509 lua_call(L, lua_gettop(L) - 1, 1);
jbe@137 510 jsontype = lua_tostring(L, -1);
jbe@137 511 if (jsontype && !strcmp(jsontype, "null")) lua_pushboolean(L, 1);
jbe@137 512 else lua_pushboolean(L, 0);
jbe@137 513 return 1;
jbe@130 514 }
jbe@130 515
jbe@138 516 #define json_setnull_unknownmt_idx 3
jbe@138 517 #define json_setnull_objectmt_idx 4
jbe@138 518 #define json_setnull_arraymt_idx 5
jbe@138 519 #define json_setnull_shadowtbl_idx 6
jbe@138 520
jbe@131 521 static int json_setnull(lua_State *L) {
jbe@138 522 // truncate stack to two elements:
jbe@131 523 lua_settop(L, 2);
jbe@138 524 // push json_unknownmt to stack position 3:
jbe@144 525 json_regfetch(L, unknownmt);
jbe@138 526 // push json_objectmt to stack position 4:
jbe@144 527 json_regfetch(L, objectmt);
jbe@138 528 // push json_arraymt to stack position 5:
jbe@144 529 json_regfetch(L, arraymt);
jbe@138 530 // push json_shadowtbl to stack position 6:
jbe@144 531 json_regfetch(L, shadowtbl);
jbe@138 532 //
jbe@138 533 lua_getmetatable(L, 1);
jbe@138 534 if (
jbe@138 535 !lua_rawequal(L, -1, json_setnull_unknownmt_idx) &&
jbe@138 536 !lua_rawequal(L, -1, json_setnull_objectmt_idx) &&
jbe@138 537 !lua_rawequal(L, -1, json_setnull_arraymt_idx)
jbe@138 538 ) {
jbe@138 539 lua_pushvalue(L, json_setnull_unknownmt_idx);
jbe@138 540 lua_setmetatable(L, 1);
jbe@138 541 }
jbe@131 542 lua_pushvalue(L, 1);
jbe@138 543 lua_rawget(L, json_setnull_shadowtbl_idx);
jbe@131 544 if (lua_isnil(L, -1)) {
jbe@131 545 lua_newtable(L);
jbe@131 546 lua_pushvalue(L, 1);
jbe@131 547 lua_pushvalue(L, -2);
jbe@138 548 lua_rawset(L, json_setnull_shadowtbl_idx);
jbe@131 549 }
jbe@131 550 lua_pushvalue(L, 2);
jbe@145 551 json_pushlightref(L, nullmark);
jbe@131 552 lua_rawset(L, -3);
jbe@131 553 return 0;
jbe@131 554 }
jbe@131 555
jbe@130 556 static int json_len(lua_State *L) {
jbe@130 557 lua_settop(L, 1);
jbe@144 558 json_regfetch(L, shadowtbl);
jbe@130 559 lua_pushvalue(L, 1);
jbe@138 560 lua_rawget(L, -2);
jbe@138 561 lua_pushinteger(L, lua_rawlen(L, lua_isnil(L, -1) ? 1 : -1));
jbe@123 562 return 1;
jbe@123 563 }
jbe@123 564
jbe@141 565 #define json_index_nullmark_idx 3
jbe@141 566 #define json_index_shadowtbl_idx 4
jbe@141 567
jbe@130 568 static int json_index(lua_State *L) {
jbe@130 569 lua_settop(L, 2);
jbe@145 570 json_pushlightref(L, nullmark); // on stack position 3
jbe@144 571 json_regfetch(L, shadowtbl);
jbe@130 572 lua_pushvalue(L, 1);
jbe@141 573 lua_rawget(L, json_index_shadowtbl_idx);
jbe@139 574 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@130 575 lua_pushvalue(L, 2);
jbe@130 576 lua_rawget(L, -2);
jbe@141 577 if (lua_rawequal(L, -1, json_index_nullmark_idx)) lua_pushnil(L);
jbe@127 578 return 1;
jbe@127 579 }
jbe@127 580
jbe@130 581 static int json_newindex(lua_State *L) {
jbe@130 582 lua_settop(L, 3);
jbe@144 583 json_regfetch(L, shadowtbl);
jbe@123 584 lua_pushvalue(L, 1);
jbe@143 585 lua_rawget(L, -2);
jbe@130 586 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@130 587 lua_replace(L, 1);
jbe@139 588 lua_settop(L, 3);
jbe@130 589 lua_rawset(L, 1);
jbe@121 590 return 1;
jbe@121 591 }
jbe@121 592
jbe@139 593 #define json_pairs_iterfunc_nullmark_idx 3
jbe@139 594 #define json_pairs_iterfunc_shadowtbl_idx 4
jbe@139 595
jbe@135 596 static int json_pairs_iterfunc(lua_State *L) {
jbe@135 597 lua_settop(L, 2);
jbe@145 598 json_pushlightref(L, nullmark); // on stack position 3
jbe@144 599 json_regfetch(L, shadowtbl);
jbe@135 600 lua_pushvalue(L, 1);
jbe@139 601 lua_rawget(L, json_pairs_iterfunc_shadowtbl_idx);
jbe@135 602 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@135 603 lua_pushvalue(L, 2);
jbe@135 604 if (!lua_next(L, -2)) return 0;
jbe@139 605 if (lua_rawequal(L, -1, json_pairs_iterfunc_nullmark_idx)) {
jbe@135 606 lua_pop(L, 1);
jbe@135 607 lua_pushnil(L);
jbe@135 608 }
jbe@135 609 return 2;
jbe@135 610 }
jbe@135 611
jbe@135 612 static int json_pairs(lua_State *L) {
jbe@139 613 lua_pushcfunction(L, json_pairs_iterfunc);
jbe@135 614 lua_pushvalue(L, 1);
jbe@135 615 lua_pushnil(L);
jbe@135 616 return 3;
jbe@135 617 }
jbe@135 618
jbe@139 619 #define json_ipairs_iterfunc_nullmark_idx 3
jbe@139 620 #define json_ipairs_iterfunc_shadowtbl_idx 4
jbe@139 621
jbe@134 622 static int json_ipairs_iterfunc(lua_State *L) {
jbe@134 623 int idx;
jbe@134 624 lua_settop(L, 2);
jbe@145 625 json_pushlightref(L, nullmark); // on stack position 3
jbe@144 626 json_regfetch(L, shadowtbl);
jbe@134 627 idx = lua_tointeger(L, 2) + 1;
jbe@134 628 lua_pushvalue(L, 1);
jbe@139 629 lua_rawget(L, json_ipairs_iterfunc_shadowtbl_idx);
jbe@134 630 if (lua_isnil(L, -1)) return luaL_error(L, "Shadow table not found");
jbe@134 631 lua_rawgeti(L, -1, idx);
jbe@134 632 if (lua_isnil(L, -1)) return 0;
jbe@134 633 lua_pushinteger(L, idx);
jbe@139 634 if (lua_rawequal(L, -2, json_ipairs_iterfunc_nullmark_idx)) lua_pushnil(L);
jbe@134 635 else lua_pushvalue(L, -2);
jbe@134 636 return 2;
jbe@134 637 }
jbe@134 638
jbe@134 639 static int json_ipairs(lua_State *L) {
jbe@139 640 lua_pushcfunction(L, json_ipairs_iterfunc);
jbe@134 641 lua_pushvalue(L, 1);
jbe@134 642 lua_pushinteger(L, 0);
jbe@134 643 return 3;
jbe@134 644 }
jbe@134 645
jbe@121 646 static const struct luaL_Reg json_module_functions[] = {
jbe@133 647 {"object", json_object},
jbe@133 648 {"array", json_array},
jbe@121 649 {"import", json_import},
jbe@130 650 {"get", json_get},
jbe@127 651 {"type", json_type},
jbe@123 652 {"isnull", json_isnull},
jbe@131 653 {"setnull", json_setnull},
jbe@121 654 {NULL, NULL}
jbe@121 655 };
jbe@121 656
jbe@126 657 static const struct luaL_Reg json_metatable_functions[] = {
jbe@130 658 {"__len", json_len},
jbe@130 659 {"__index", json_index},
jbe@130 660 {"__newindex", json_newindex},
jbe@135 661 {"__pairs", json_pairs},
jbe@134 662 {"__ipairs", json_ipairs},
jbe@126 663 {NULL, NULL}
jbe@126 664 };
jbe@126 665
jbe@121 666 int luaopen_json(lua_State *L) {
jbe@126 667 lua_settop(L, 0);
jbe@138 668 lua_newtable(L); // library
jbe@138 669 lua_newtable(L);
jbe@138 670 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 671 json_regstore(L, unknownmt);
jbe@138 672 lua_setfield(L, 1, "ambiguous_mt");
jbe@138 673 lua_newtable(L);
jbe@138 674 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 675 json_regstore(L, objectmt);
jbe@138 676 lua_setfield(L, 1, "object_mt");
jbe@138 677 lua_newtable(L);
jbe@138 678 luaL_setfuncs(L, json_metatable_functions, 0);
jbe@144 679 json_regstore(L, arraymt);
jbe@138 680 lua_setfield(L, 1, "array_mt");
jbe@138 681 lua_newtable(L); // ephemeron table to store shadow tables for each JSON object/array to allow NULL values returned as nil
jbe@138 682 lua_newtable(L); // metatable for ephemeron table
jbe@121 683 lua_pushliteral(L, "__mode");
jbe@121 684 lua_pushliteral(L, "k");
jbe@138 685 lua_rawset(L, -3);
jbe@138 686 lua_setmetatable(L, -2);
jbe@144 687 json_regstore(L, shadowtbl);
jbe@138 688 lua_settop(L, 1);
jbe@138 689 luaL_setfuncs(L, json_module_functions, 0);
jbe@121 690 return 1;
jbe@121 691 }

Impressum / About Us