liblua/llex.c

   1 /*
   2 ** $Id: llex.c,v 2.63 2013/03/16 21:10:18 roberto Exp $
   3 ** Lexical Analyzer
   4 ** See Copyright Notice in lua.h
   5 */
   6
   7
   8 #include <locale.h>
   9 #include <string.h>
  10
  11 #define llex_c
  12 #define LUA_CORE
  13
  14 #include "lua.h"
  15
  16 #include "lctype.h"
  17 #include "ldo.h"
  18 #include "llex.h"
  19 #include "lobject.h"
  20 #include "lparser.h"
  21 #include "lstate.h"
  22 #include "lstring.h"
  23 #include "ltable.h"
  24 #include "lzio.h"
  25
  26
  27
  28 #define next(ls) (ls->current = zgetc(ls->z))
  29
  30
  31
  32 #define currIsNewline(ls)       (ls->current == '\n' || ls->current == '\r')
  33
  34
  35 /* ORDER RESERVED */
  36 static const char *const luaX_tokens [] = {
  37     "and", "break", "do", "else", "elseif",
  38     "end", "false", "for", "function", "goto", "if",
  39     "in", "local", "nil", "not", "or", "repeat",
  40     "return", "then", "true", "until", "while",
  41     "..", "...", "==", ">=", "<=", "~=", "::", "<eof>",
  42     "<number>", "<name>", "<string>"
  43 };
  44
  45
  46 #define save_and_next(ls) (save(ls, ls->current), next(ls))
  47
  48
  49 static l_noret lexerror (LexState *ls, const char *msg, int token);
  50
  51
  52 static void save (LexState *ls, int c) {
  53   Mbuffer *b = ls->buff;
  54   if (luaZ_bufflen(b) + 1 > luaZ_sizebuffer(b)) {
  55     size_t newsize;
  56     if (luaZ_sizebuffer(b) >= MAX_SIZET/2)
  57       lexerror(ls, "lexical element too long", 0);
  58     newsize = luaZ_sizebuffer(b) * 2;
  59     luaZ_resizebuffer(ls->L, b, newsize);
  60   }
  61   b->buffer[luaZ_bufflen(b)++] = cast(char, c);
  62 }
  63
  64
  65 void luaX_init (lua_State *L) {
  66   int i;
  67   for (i=0; i<NUM_RESERVED; i++) {
  68     TString *ts = luaS_new(L, luaX_tokens[i]);
  69     luaS_fix(ts);  /* reserved words are never collected */
  70     ts->tsv.extra = cast_byte(i+1);  /* reserved word */
  71   }
  72 }
  73
  74
  75 const char *luaX_token2str (LexState *ls, int token) {
  76   if (token < FIRST_RESERVED) {  /* single-byte symbols? */
  77     lua_assert(token == cast(unsigned char, token));
  78     return (lisprint(token)) ? luaO_pushfstring(ls->L, LUA_QL("%c"), token) :
  79                               luaO_pushfstring(ls->L, "char(%d)", token);
  80   }
  81   else {
  82     const char *s = luaX_tokens[token - FIRST_RESERVED];
  83     if (token < TK_EOS)  /* fixed format (symbols and reserved words)? */
  84       return luaO_pushfstring(ls->L, LUA_QS, s);
  85     else  /* names, strings, and numerals */
  86       return s;
  87   }
  88 }
  89
  90
  91 static const char *txtToken (LexState *ls, int token) {
  92   switch (token) {
  93     case TK_NAME:
  94     case TK_STRING:
  95     case TK_NUMBER:
  96       save(ls, '\0');
  97       return luaO_pushfstring(ls->L, LUA_QS, luaZ_buffer(ls->buff));
  98     default:
  99       return luaX_token2str(ls, token);
 100   }
 101 }
 102
 103
 104 static l_noret lexerror (LexState *ls, const char *msg, int token) {
 105   char buff[LUA_IDSIZE];
 106   luaO_chunkid(buff, getstr(ls->source), LUA_IDSIZE);
 107   msg = luaO_pushfstring(ls->L, "%s:%d: %s", buff, ls->linenumber, msg);
 108   if (token)
 109     luaO_pushfstring(ls->L, "%s near %s", msg, txtToken(ls, token));
 110   luaD_throw(ls->L, LUA_ERRSYNTAX);
 111 }
 112
 113
 114 l_noret luaX_syntaxerror (LexState *ls, const char *msg) {
 115   lexerror(ls, msg, ls->t.token);
 116 }
 117
 118
 119 /*
 120 ** creates a new string and anchors it in function's table so that
 121 ** it will not be collected until the end of the function's compilation
 122 ** (by that time it should be anchored in function's prototype)
 123 */
 124 TString *luaX_newstring (LexState *ls, const char *str, size_t l) {
 125   lua_State *L = ls->L;
 126   TValue *o;  /* entry for `str' */
 127   TString *ts = luaS_newlstr(L, str, l);  /* create new string */
 128   setsvalue2s(L, L->top++, ts);  /* temporarily anchor it in stack */
 129   o = luaH_set(L, ls->fs->h, L->top - 1);
 130   if (ttisnil(o)) {  /* not in use yet? (see 'addK') */
 131     /* boolean value does not need GC barrier;
 132        table has no metatable, so it does not need to invalidate cache */
 133     setbvalue(o, 1);  /* t[string] = true */
 134     luaC_checkGC(L);
 135   }
 136   L->top--;  /* remove string from stack */
 137   return ts;
 138 }
 139
 140
 141 /*
 142 ** increment line number and skips newline sequence (any of
 143 ** \n, \r, \n\r, or \r\n)
 144 */
 145 static void inclinenumber (LexState *ls) {
 146   int old = ls->current;
 147   lua_assert(currIsNewline(ls));
 148   next(ls);  /* skip `\n' or `\r' */
 149   if (currIsNewline(ls) && ls->current != old)
 150     next(ls);  /* skip `\n\r' or `\r\n' */
 151   if (++ls->linenumber >= MAX_INT)
 152     luaX_syntaxerror(ls, "chunk has too many lines");
 153 }
 154
 155
 156 void luaX_setinput (lua_State *L, LexState *ls, ZIO *z, TString *source,
 157                     int firstchar) {
 158   ls->decpoint = '.';
 159   ls->L = L;
 160   ls->current = firstchar;
 161   ls->lookahead.token = TK_EOS;  /* no look-ahead token */
 162   ls->z = z;
 163   ls->fs = NULL;
 164   ls->linenumber = 1;
 165   ls->lastline = 1;
 166   ls->source = source;
 167   ls->envn = luaS_new(L, LUA_ENV);  /* create env name */
 168   luaS_fix(ls->envn);  /* never collect this name */
 169   luaZ_resizebuffer(ls->L, ls->buff, LUA_MINBUFFER);  /* initialize buffer */
 170 }
 171
 172
 173
 174 /*
 175 ** =======================================================
 176 ** LEXICAL ANALYZER
 177 ** =======================================================
 178 */
 179
 180
 181
 182 static int check_next (LexState *ls, const char *set) {
 183   if (ls->current == '\0' || !strchr(set, ls->current))
 184     return 0;
 185   save_and_next(ls);
 186   return 1;
 187 }
 188
 189
 190 /*
 191 ** change all characters 'from' in buffer to 'to'
 192 */
 193 static void buffreplace (LexState *ls, char from, char to) {
 194   size_t n = luaZ_bufflen(ls->buff);
 195   char *p = luaZ_buffer(ls->buff);
 196   while (n--)
 197     if (p[n] == from) p[n] = to;
 198 }
 199
 200
 201 #if !defined(getlocaledecpoint)
 202 #define getlocaledecpoint()     (localeconv()->decimal_point[0])
 203 #endif
 204
 205
 206 #define buff2d(b,e)     luaO_str2d(luaZ_buffer(b), luaZ_bufflen(b) - 1, e)
 207
 208 /*
 209 ** in case of format error, try to change decimal point separator to
 210 ** the one defined in the current locale and check again
 211 */
 212 static void trydecpoint (LexState *ls, SemInfo *seminfo) {
 213   char old = ls->decpoint;
 214   ls->decpoint = getlocaledecpoint();
 215   buffreplace(ls, old, ls->decpoint);  /* try new decimal separator */
 216   if (!buff2d(ls->buff, &seminfo->r)) {
 217     /* format error with correct decimal point: no more options */
 218     buffreplace(ls, ls->decpoint, '.');  /* undo change (for error message) */
 219     lexerror(ls, "malformed number", TK_NUMBER);
 220   }
 221 }
 222
 223
 224 /* LUA_NUMBER */
 225 /*
 226 ** this function is quite liberal in what it accepts, as 'luaO_str2d'
 227 ** will reject ill-formed numerals.
 228 */
 229 static void read_numeral (LexState *ls, SemInfo *seminfo) {
 230   const char *expo = "Ee";
 231   int first = ls->current;
 232   lua_assert(lisdigit(ls->current));
 233   save_and_next(ls);
 234   if (first == '0' && check_next(ls, "Xx"))  /* hexadecimal? */
 235     expo = "Pp";
 236   for (;;) {
 237     if (check_next(ls, expo))  /* exponent part? */
 238       check_next(ls, "+-");  /* optional exponent sign */
 239     if (lisxdigit(ls->current) || ls->current == '.')
 240       save_and_next(ls);
 241     else  break;
 242   }
 243   save(ls, '\0');
 244   buffreplace(ls, '.', ls->decpoint);  /* follow locale for decimal point */
 245   if (!buff2d(ls->buff, &seminfo->r))  /* format error? */
 246     trydecpoint(ls, seminfo); /* try to update decimal point separator */
 247 }
 248
 249
 250 /*
 251 ** skip a sequence '[=*[' or ']=*]' and return its number of '='s or
 252 ** -1 if sequence is malformed
 253 */
 254 static int skip_sep (LexState *ls) {
 255   int count = 0;
 256   int s = ls->current;
 257   lua_assert(s == '[' || s == ']');
 258   save_and_next(ls);
 259   while (ls->current == '=') {
 260     save_and_next(ls);
 261     count++;
 262   }
 263   return (ls->current == s) ? count : (-count) - 1;
 264 }
 265
 266
 267 static void read_long_string (LexState *ls, SemInfo *seminfo, int sep) {
 268   save_and_next(ls);  /* skip 2nd `[' */
 269   if (currIsNewline(ls))  /* string starts with a newline? */
 270     inclinenumber(ls);  /* skip it */
 271   for (;;) {
 272     switch (ls->current) {
 273       case EOZ:
 274         lexerror(ls, (seminfo) ? "unfinished long string" :
 275                                  "unfinished long comment", TK_EOS);
 276         break;  /* to avoid warnings */
 277       case ']': {
 278         if (skip_sep(ls) == sep) {
 279           save_and_next(ls);  /* skip 2nd `]' */
 280           goto endloop;
 281         }
 282         break;
 283       }
 284       case '\n': case '\r': {
 285         save(ls, '\n');
 286         inclinenumber(ls);
 287         if (!seminfo) luaZ_resetbuffer(ls->buff);  /* avoid wasting space */
 288         break;
 289       }
 290       default: {
 291         if (seminfo) save_and_next(ls);
 292         else next(ls);
 293       }
 294     }
 295   } endloop:
 296   if (seminfo)
 297     seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + (2 + sep),
 298                                      luaZ_bufflen(ls->buff) - 2*(2 + sep));
 299 }
 300
 301
 302 static void escerror (LexState *ls, int *c, int n, const char *msg) {
 303   int i;
 304   luaZ_resetbuffer(ls->buff);  /* prepare error message */
 305   save(ls, '\\');
 306   for (i = 0; i < n && c[i] != EOZ; i++)
 307     save(ls, c[i]);
 308   lexerror(ls, msg, TK_STRING);
 309 }
 310
 311
 312 static int readhexaesc (LexState *ls) {
 313   int c[3], i;  /* keep input for error message */
 314   int r = 0;  /* result accumulator */
 315   c[0] = 'x';  /* for error message */
 316   for (i = 1; i < 3; i++) {  /* read two hexadecimal digits */
 317     c[i] = next(ls);
 318     if (!lisxdigit(c[i]))
 319       escerror(ls, c, i + 1, "hexadecimal digit expected");
 320     r = (r << 4) + luaO_hexavalue(c[i]);
 321   }
 322   return r;
 323 }
 324
 325
 326 static int readdecesc (LexState *ls) {
 327   int c[3], i;
 328   int r = 0;  /* result accumulator */
 329   for (i = 0; i < 3 && lisdigit(ls->current); i++) {  /* read up to 3 digits */
 330     c[i] = ls->current;
 331     r = 10*r + c[i] - '0';
 332     next(ls);
 333   }
 334   if (r > UCHAR_MAX)
 335     escerror(ls, c, i, "decimal escape too large");
 336   return r;
 337 }
 338
 339
 340 static void read_string (LexState *ls, int del, SemInfo *seminfo) {
 341   save_and_next(ls);  /* keep delimiter (for error messages) */
 342   while (ls->current != del) {
 343     switch (ls->current) {
 344       case EOZ:
 345         lexerror(ls, "unfinished string", TK_EOS);
 346         break;  /* to avoid warnings */
 347       case '\n':
 348       case '\r':
 349         lexerror(ls, "unfinished string", TK_STRING);
 350         break;  /* to avoid warnings */
 351       case '\\': {  /* escape sequences */
 352         int c;  /* final character to be saved */
 353         next(ls);  /* do not save the `\' */
 354         switch (ls->current) {
 355           case 'a': c = '\a'; goto read_save;
 356           case 'b': c = '\b'; goto read_save;
 357           case 'f': c = '\f'; goto read_save;
 358           case 'n': c = '\n'; goto read_save;
 359           case 'r': c = '\r'; goto read_save;
 360           case 't': c = '\t'; goto read_save;
 361           case 'v': c = '\v'; goto read_save;
 362           case 'x': c = readhexaesc(ls); goto read_save;
 363           case '\n': case '\r':
 364             inclinenumber(ls); c = '\n'; goto only_save;
 365           case '\\': case '\"': case '\'':
 366             c = ls->current; goto read_save;
 367           case EOZ: goto no_save;  /* will raise an error next loop */
 368           case 'z': {  /* zap following span of spaces */
 369             next(ls);  /* skip the 'z' */
 370             while (lisspace(ls->current)) {
 371               if (currIsNewline(ls)) inclinenumber(ls);
 372               else next(ls);
 373             }
 374             goto no_save;
 375           }
 376           default: {
 377             if (!lisdigit(ls->current))
 378               escerror(ls, &ls->current, 1, "invalid escape sequence");
 379             /* digital escape \ddd */
 380             c = readdecesc(ls);
 381             goto only_save;
 382           }
 383         }
 384        read_save: next(ls);  /* read next character */
 385        only_save: save(ls, c);  /* save 'c' */
 386        no_save: break;
 387       }
 388       default:
 389         save_and_next(ls);
 390     }
 391   }
 392   save_and_next(ls);  /* skip delimiter */
 393   seminfo->ts = luaX_newstring(ls, luaZ_buffer(ls->buff) + 1,
 394                                    luaZ_bufflen(ls->buff) - 2);
 395 }
 396
 397
 398 static int llex (LexState *ls, SemInfo *seminfo) {
 399   luaZ_resetbuffer(ls->buff);
 400   for (;;) {
 401     switch (ls->current) {
 402       case '\n': case '\r': {  /* line breaks */
 403         inclinenumber(ls);
 404         break;
 405       }
 406       case ' ': case '\f': case '\t': case '\v': {  /* spaces */
 407         next(ls);
 408         break;
 409       }
 410       case '-': {  /* '-' or '--' (comment) */
 411         next(ls);
 412         if (ls->current != '-') return '-';
 413         /* else is a comment */
 414         next(ls);
 415         if (ls->current == '[') {  /* long comment? */
 416           int sep = skip_sep(ls);
 417           luaZ_resetbuffer(ls->buff);  /* `skip_sep' may dirty the buffer */
 418           if (sep >= 0) {
 419             read_long_string(ls, NULL, sep);  /* skip long comment */
 420             luaZ_resetbuffer(ls->buff);  /* previous call may dirty the buff. */
 421             break;
 422           }
 423         }
 424         /* else short comment */
 425         while (!currIsNewline(ls) && ls->current != EOZ)
 426           next(ls);  /* skip until end of line (or end of file) */
 427         break;
 428       }
 429       case '[': {  /* long string or simply '[' */
 430         int sep = skip_sep(ls);
 431         if (sep >= 0) {
 432           read_long_string(ls, seminfo, sep);
 433           return TK_STRING;
 434         }
 435         else if (sep == -1) return '[';
 436         else lexerror(ls, "invalid long string delimiter", TK_STRING);
 437       }
 438       case '=': {
 439         next(ls);
 440         if (ls->current != '=') return '=';
 441         else { next(ls); return TK_EQ; }
 442       }
 443       case '<': {
 444         next(ls);
 445         if (ls->current != '=') return '<';
 446         else { next(ls); return TK_LE; }
 447       }
 448       case '>': {
 449         next(ls);
 450         if (ls->current != '=') return '>';
 451         else { next(ls); return TK_GE; }
 452       }
 453       case '~': {
 454         next(ls);
 455         if (ls->current != '=') return '~';
 456         else { next(ls); return TK_NE; }
 457       }
 458       case ':': {
 459         next(ls);
 460         if (ls->current != ':') return ':';
 461         else { next(ls); return TK_DBCOLON; }
 462       }
 463       case '"': case '\'': {  /* short literal strings */
 464         read_string(ls, ls->current, seminfo);
 465         return TK_STRING;
 466       }
 467       case '.': {  /* '.', '..', '...', or number */
 468         save_and_next(ls);
 469         if (check_next(ls, ".")) {
 470           if (check_next(ls, "."))
 471             return TK_DOTS;   /* '...' */
 472           else return TK_CONCAT;   /* '..' */
 473         }
 474         else if (!lisdigit(ls->current)) return '.';
 475         /* else go through */
 476       }
 477       case '0': case '1': case '2': case '3': case '4':
 478       case '5': case '6': case '7': case '8': case '9': {
 479         read_numeral(ls, seminfo);
 480         return TK_NUMBER;
 481       }
 482       case EOZ: {
 483         return TK_EOS;
 484       }
 485       default: {
 486         if (lislalpha(ls->current)) {  /* identifier or reserved word? */
 487           TString *ts;
 488           do {
 489             save_and_next(ls);
 490           } while (lislalnum(ls->current));
 491           ts = luaX_newstring(ls, luaZ_buffer(ls->buff),
 492                                   luaZ_bufflen(ls->buff));
 493           seminfo->ts = ts;
 494           if (isreserved(ts))  /* reserved word? */
 495             return ts->tsv.extra - 1 + FIRST_RESERVED;
 496           else {
 497             return TK_NAME;
 498           }
 499         }
 500         else {  /* single-char tokens (+ - / ...) */
 501           int c = ls->current;
 502           next(ls);
 503           return c;
 504         }
 505       }
 506     }
 507   }
 508 }
 509
 510
 511 void luaX_next (LexState *ls) {
 512   ls->lastline = ls->linenumber;
 513   if (ls->lookahead.token != TK_EOS) {  /* is there a look-ahead token? */
 514     ls->t = ls->lookahead;  /* use this one */
 515     ls->lookahead.token = TK_EOS;  /* and discharge it */
 516   }
 517   else
 518     ls->t.token = llex(ls, &ls->t.seminfo);  /* read next token */
 519 }
 520
 521
 522 int luaX_lookahead (LexState *ls) {
 523   lua_assert(ls->lookahead.token == TK_EOS);
 524   ls->lookahead.token = llex(ls, &ls->lookahead.seminfo);
 525   return ls->lookahead.token;
 526 }
 527