src/scan-gram.l

   1 /* Bison Grammar Scanner                             -*- C -*-
   2
   3    Copyright (C) 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
   4
   5    This file is part of Bison, the GNU Compiler Compiler.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  20    02110-1301  USA
  21 */
  22
  23 %option debug nodefault nounput noyywrap never-interactive
  24 %option prefix="gram_" outfile="lex.yy.c"
  25
  26 %{
  27 #include <config.h>
  28 #include "system.h"
  29
  30 /* Work around a bug in flex 2.5.31.  See Debian bug 333231
  31    <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=333231>.  */
  32 #undef gram_wrap
  33 #define gram_wrap() 1
  34
  35 #define FLEX_PREFIX(Id) gram_ ## Id
  36 #include "flex-scanner.h"
  37
  38 #include "complain.h"
  39 #include "files.h"
  40 #include "getargs.h"    /* yacc_flag */
  41 #include "gram.h"
  42 #include "quotearg.h"
  43 #include "reader.h"
  44 #include "uniqstr.h"
  45
  46 #include <mbswidth.h>
  47 #include <quote.h>
  48
  49 #include "scan-gram.h"
  50
  51 #define YY_DECL GRAM_LEX_DECL
  52
  53 #define YY_USER_INIT                                    \
  54    code_start = scanner_cursor = loc->start;            \
  55
  56 /* Location of scanner cursor.  */
  57 boundary scanner_cursor;
  58
  59 #define YY_USER_ACTION  location_compute (loc, &scanner_cursor, yytext, yyleng);
  60
  61 static size_t no_cr_read (FILE *, char *, size_t);
  62 #define YY_INPUT(buf, result, size) ((result) = no_cr_read (yyin, buf, size))
  63
  64 /* A string representing the most recently saved token.  */
  65 char *last_string;
  66
  67 void
  68 gram_scanner_last_string_free (void)
  69 {
  70   STRING_FREE;
  71 }
  72
  73 /* The location of the most recently saved token, if it was a
  74    BRACED_CODE token; otherwise, this has an unspecified value.  */
  75 location gram_last_braced_code_loc;
  76
  77 static void handle_syncline (char *, location);
  78 static unsigned long int scan_integer (char const *p, int base, location loc);
  79 static int convert_ucn_to_byte (char const *hex_text);
  80 static void unexpected_eof (boundary, char const *);
  81 static void unexpected_newline (boundary, char const *);
  82
  83 %}
  84  /* A C-like comment in directives/rules. */
  85 %x SC_YACC_COMMENT
  86  /* Strings and characters in directives/rules. */
  87 %x SC_ESCAPED_STRING SC_ESCAPED_CHARACTER
  88  /* A identifier was just read in directives/rules.  Special state
  89     to capture the sequence `identifier :'. */
  90 %x SC_AFTER_IDENTIFIER
  91
  92  /* Three types of user code:
  93     - prologue (code between `%{' `%}' in the first section, before %%);
  94     - actions, printers, union, etc, (between braced in the middle section);
  95     - epilogue (everything after the second %%). */
  96 %x SC_PROLOGUE SC_BRACED_CODE SC_EPILOGUE
  97  /* C and C++ comments in code. */
  98 %x SC_COMMENT SC_LINE_COMMENT
  99  /* Strings and characters in code. */
 100 %x SC_STRING SC_CHARACTER
 101
 102 letter    [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
 103 id        {letter}({letter}|[0-9])*
 104 directive %{letter}({letter}|[0-9]|-)*
 105 int       [0-9]+
 106
 107 /* POSIX says that a tag must be both an id and a C union member, but
 108    historically almost any character is allowed in a tag.  We disallow
 109    NUL and newline, as this simplifies our implementation.  */
 110 tag      [^\0\n>]+
 111
 112 /* Zero or more instances of backslash-newline.  Following GCC, allow
 113    white space between the backslash and the newline.  */
 114 splice   (\\[ \f\t\v]*\n)*
 115
 116 %%
 117 %{
 118   /* Nesting level of the current code in braces.  */
 119   int braces_level IF_LINT (= 0);
 120
 121   /* Parent context state, when applicable.  */
 122   int context_state IF_LINT (= 0);
 123
 124   /* Location of most recent identifier, when applicable.  */
 125   location id_loc IF_LINT (= empty_location);
 126
 127   /* Where containing code started, when applicable.  Its initial
 128      value is relevant only when yylex is invoked in the SC_EPILOGUE
 129      start condition.  */
 130   boundary code_start = scanner_cursor;
 131
 132   /* Where containing comment or string or character literal started,
 133      when applicable.  */
 134   boundary token_start IF_LINT (= scanner_cursor);
 135 %}
 136
 137
 138   /*-----------------------.
 139   | Scanning white space.  |
 140   `-----------------------*/
 141
 142 <INITIAL,SC_AFTER_IDENTIFIER>
 143 {
 144   /* Comments and white space.  */
 145   ","          warn_at (*loc, _("stray `,' treated as white space"));
 146   [ \f\n\t\v]  |
 147   "//".*       ;
 148   "/*" {
 149     token_start = loc->start;
 150     context_state = YY_START;
 151     BEGIN SC_YACC_COMMENT;
 152   }
 153
 154   /* #line directives are not documented, and may be withdrawn or
 155      modified in future versions of Bison.  */
 156   ^"#line "{int}" \"".*"\"\n" {
 157     handle_syncline (yytext + sizeof "#line " - 1, *loc);
 158   }
 159 }
 160
 161
 162   /*----------------------------.
 163   | Scanning Bison directives.  |
 164   `----------------------------*/
 165 <INITIAL>
 166 {
 167   "%binary"                         return PERCENT_NONASSOC;
 168   "%debug"                          return PERCENT_DEBUG;
 169   "%default"[-_]"prec"              return PERCENT_DEFAULT_PREC;
 170   "%define"                         return PERCENT_DEFINE;
 171   "%defines"                        return PERCENT_DEFINES;
 172   "%destructor"                     return PERCENT_DESTRUCTOR;
 173   "%dprec"                          return PERCENT_DPREC;
 174   "%error"[-_]"verbose"             return PERCENT_ERROR_VERBOSE;
 175   "%expect"                         return PERCENT_EXPECT;
 176   "%expect"[-_]"rr"                 return PERCENT_EXPECT_RR;
 177   "%file-prefix"                    return PERCENT_FILE_PREFIX;
 178   "%fixed"[-_]"output"[-_]"files"   return PERCENT_YACC;
 179   "%initial-action"                 return PERCENT_INITIAL_ACTION;
 180   "%glr-parser"                     return PERCENT_GLR_PARSER;
 181   "%left"                           return PERCENT_LEFT;
 182   "%lex-param"                      return PERCENT_LEX_PARAM;
 183   "%locations"                      return PERCENT_LOCATIONS;
 184   "%merge"                          return PERCENT_MERGE;
 185   "%name"[-_]"prefix"               return PERCENT_NAME_PREFIX;
 186   "%no"[-_]"default"[-_]"prec"      return PERCENT_NO_DEFAULT_PREC;
 187   "%no"[-_]"lines"                  return PERCENT_NO_LINES;
 188   "%nonassoc"                       return PERCENT_NONASSOC;
 189   "%nondeterministic-parser"        return PERCENT_NONDETERMINISTIC_PARSER;
 190   "%nterm"                          return PERCENT_NTERM;
 191   "%output"                         return PERCENT_OUTPUT;
 192   "%parse-param"                    return PERCENT_PARSE_PARAM;
 193   "%prec"                           return PERCENT_PREC;
 194   "%printer"                        return PERCENT_PRINTER;
 195   "%pure"[-_]"parser"               return PERCENT_PURE_PARSER;
 196   "%require"                        return PERCENT_REQUIRE;
 197   "%right"                          return PERCENT_RIGHT;
 198   "%skeleton"                       return PERCENT_SKELETON;
 199   "%start"                          return PERCENT_START;
 200   "%term"                           return PERCENT_TOKEN;
 201   "%token"                          return PERCENT_TOKEN;
 202   "%token"[-_]"table"               return PERCENT_TOKEN_TABLE;
 203   "%type"                           return PERCENT_TYPE;
 204   "%union"                          return PERCENT_UNION;
 205   "%verbose"                        return PERCENT_VERBOSE;
 206   "%yacc"                           return PERCENT_YACC;
 207
 208   {directive} {
 209     complain_at (*loc, _("invalid directive: %s"), quote (yytext));
 210   }
 211
 212   "="                     return EQUAL;
 213   "|"                     return PIPE;
 214   ";"                     return SEMICOLON;
 215
 216   {id} {
 217     val->uniqstr = uniqstr_new (yytext);
 218     id_loc = *loc;
 219     BEGIN SC_AFTER_IDENTIFIER;
 220   }
 221
 222   {int} {
 223     val->integer = scan_integer (yytext, 10, *loc);
 224     return INT;
 225   }
 226   0[xX][0-9abcdefABCDEF]+ {
 227     val->integer = scan_integer (yytext, 16, *loc);
 228     return INT;
 229   }
 230
 231   /* Characters.  We don't check there is only one.  */
 232   "'"         STRING_GROW; token_start = loc->start; BEGIN SC_ESCAPED_CHARACTER;
 233
 234   /* Strings. */
 235   "\""        token_start = loc->start; BEGIN SC_ESCAPED_STRING;
 236
 237   /* Prologue. */
 238   "%{"        code_start = loc->start; BEGIN SC_PROLOGUE;
 239
 240   /* Code in between braces.  */
 241   "{" {
 242     if (current_rule && current_rule->action)
 243       grammar_midrule_action ();
 244     STRING_GROW;
 245     braces_level = 0;
 246     code_start = loc->start;
 247     BEGIN SC_BRACED_CODE;
 248   }
 249
 250   /* A type. */
 251   "<"{tag}">" {
 252     obstack_grow (&obstack_for_string, yytext + 1, yyleng - 2);
 253     STRING_FINISH;
 254     val->uniqstr = uniqstr_new (last_string);
 255     STRING_FREE;
 256     return TYPE;
 257   }
 258
 259   "%%" {
 260     static int percent_percent_count;
 261     if (++percent_percent_count == 2)
 262       BEGIN SC_EPILOGUE;
 263     return PERCENT_PERCENT;
 264   }
 265
 266   . {
 267     complain_at (*loc, _("invalid character: %s"), quote (yytext));
 268   }
 269
 270   <<EOF>> {
 271     loc->start = loc->end = scanner_cursor;
 272     yyterminate ();
 273   }
 274 }
 275
 276
 277   /*-----------------------------------------------------------------.
 278   | Scanning after an identifier, checking whether a colon is next.  |
 279   `-----------------------------------------------------------------*/
 280
 281 <SC_AFTER_IDENTIFIER>
 282 {
 283   ":" {
 284     *loc = id_loc;
 285     BEGIN INITIAL;
 286     return ID_COLON;
 287   }
 288   . {
 289     scanner_cursor.column -= mbsnwidth (yytext, yyleng, 0);
 290     yyless (0);
 291     *loc = id_loc;
 292     BEGIN INITIAL;
 293     return ID;
 294   }
 295   <<EOF>> {
 296     *loc = id_loc;
 297     BEGIN INITIAL;
 298     return ID;
 299   }
 300 }
 301
 302
 303   /*---------------------------------------------------------------.
 304   | Scanning a Yacc comment.  The initial `/ *' is already eaten.  |
 305   `---------------------------------------------------------------*/
 306
 307 <SC_YACC_COMMENT>
 308 {
 309   "*/"     BEGIN context_state;
 310   .|\n     ;
 311   <<EOF>>  unexpected_eof (token_start, "*/"); BEGIN context_state;
 312 }
 313
 314
 315   /*------------------------------------------------------------.
 316   | Scanning a C comment.  The initial `/ *' is already eaten.  |
 317   `------------------------------------------------------------*/
 318
 319 <SC_COMMENT>
 320 {
 321   "*"{splice}"/"  STRING_GROW; BEGIN context_state;
 322   <<EOF>>         unexpected_eof (token_start, "*/"); BEGIN context_state;
 323 }
 324
 325
 326   /*--------------------------------------------------------------.
 327   | Scanning a line comment.  The initial `//' is already eaten.  |
 328   `--------------------------------------------------------------*/
 329
 330 <SC_LINE_COMMENT>
 331 {
 332   "\n"           STRING_GROW; BEGIN context_state;
 333   {splice}       STRING_GROW;
 334   <<EOF>>        BEGIN context_state;
 335 }
 336
 337
 338   /*------------------------------------------------.
 339   | Scanning a Bison string, including its escapes. |
 340   | The initial quote is already eaten.             |
 341   `------------------------------------------------*/
 342
 343 <SC_ESCAPED_STRING>
 344 {
 345   "\"" {
 346     STRING_FINISH;
 347     loc->start = token_start;
 348     val->chars = last_string;
 349     BEGIN INITIAL;
 350     return STRING;
 351   }
 352   \n            unexpected_newline (token_start, "\""); BEGIN INITIAL;
 353   <<EOF>>       unexpected_eof (token_start, "\"");     BEGIN INITIAL;
 354 }
 355
 356   /*----------------------------------------------------------.
 357   | Scanning a Bison character literal, decoding its escapes. |
 358   | The initial quote is already eaten.                       |
 359   `----------------------------------------------------------*/
 360
 361 <SC_ESCAPED_CHARACTER>
 362 {
 363   "'" {
 364     unsigned char last_string_1;
 365     STRING_GROW;
 366     STRING_FINISH;
 367     loc->start = token_start;
 368     val->character = last_string[1];
 369     STRING_FREE;
 370     BEGIN INITIAL;
 371     return CHAR;
 372   }
 373   \n            unexpected_newline (token_start, "'");  BEGIN INITIAL;
 374   <<EOF>>       unexpected_eof (token_start, "'");      BEGIN INITIAL;
 375 }
 376
 377 <SC_ESCAPED_CHARACTER,SC_ESCAPED_STRING>
 378 {
 379   \0        complain_at (*loc, _("invalid null character"));
 380 }
 381
 382
 383   /*----------------------------.
 384   | Decode escaped characters.  |
 385   `----------------------------*/
 386
 387 <SC_ESCAPED_STRING,SC_ESCAPED_CHARACTER>
 388 {
 389   \\[0-7]{1,3} {
 390     unsigned long int c = strtoul (yytext + 1, NULL, 8);
 391     if (UCHAR_MAX < c)
 392       complain_at (*loc, _("invalid escape sequence: %s"), quote (yytext));
 393     else if (! c)
 394       complain_at (*loc, _("invalid null character: %s"), quote (yytext));
 395     else
 396       obstack_1grow (&obstack_for_string, c);
 397   }
 398
 399   \\x[0-9abcdefABCDEF]+ {
 400     verify (UCHAR_MAX < ULONG_MAX);
 401     unsigned long int c = strtoul (yytext + 2, NULL, 16);
 402     if (UCHAR_MAX < c)
 403       complain_at (*loc, _("invalid escape sequence: %s"), quote (yytext));
 404     else if (! c)
 405       complain_at (*loc, _("invalid null character: %s"), quote (yytext));
 406     else
 407       obstack_1grow (&obstack_for_string, c);
 408   }
 409
 410   \\a   obstack_1grow (&obstack_for_string, '\a');
 411   \\b   obstack_1grow (&obstack_for_string, '\b');
 412   \\f   obstack_1grow (&obstack_for_string, '\f');
 413   \\n   obstack_1grow (&obstack_for_string, '\n');
 414   \\r   obstack_1grow (&obstack_for_string, '\r');
 415   \\t   obstack_1grow (&obstack_for_string, '\t');
 416   \\v   obstack_1grow (&obstack_for_string, '\v');
 417
 418   /* \\[\"\'?\\] would be shorter, but it confuses xgettext.  */
 419   \\("\""|"'"|"?"|"\\")  obstack_1grow (&obstack_for_string, yytext[1]);
 420
 421   \\(u|U[0-9abcdefABCDEF]{4})[0-9abcdefABCDEF]{4} {
 422     int c = convert_ucn_to_byte (yytext);
 423     if (c < 0)
 424       complain_at (*loc, _("invalid escape sequence: %s"), quote (yytext));
 425     else if (! c)
 426       complain_at (*loc, _("invalid null character: %s"), quote (yytext));
 427     else
 428       obstack_1grow (&obstack_for_string, c);
 429   }
 430   \\(.|\n)      {
 431     complain_at (*loc, _("unrecognized escape sequence: %s"), quote (yytext));
 432     STRING_GROW;
 433   }
 434 }
 435
 436   /*--------------------------------------------.
 437   | Scanning user-code characters and strings.  |
 438   `--------------------------------------------*/
 439
 440 <SC_CHARACTER,SC_STRING>
 441 {
 442   {splice}|\\{splice}[^\n\[\]]  STRING_GROW;
 443 }
 444
 445 <SC_CHARACTER>
 446 {
 447   "'"           STRING_GROW; BEGIN context_state;
 448   \n            unexpected_newline (token_start, "'"); BEGIN context_state;
 449   <<EOF>>       unexpected_eof (token_start, "'"); BEGIN context_state;
 450 }
 451
 452 <SC_STRING>
 453 {
 454   "\""          STRING_GROW; BEGIN context_state;
 455   \n            unexpected_newline (token_start, "\""); BEGIN context_state;
 456   <<EOF>>       unexpected_eof (token_start, "\""); BEGIN context_state;
 457 }
 458
 459
 460   /*---------------------------------------------------.
 461   | Strings, comments etc. can be found in user code.  |
 462   `---------------------------------------------------*/
 463
 464 <SC_BRACED_CODE,SC_PROLOGUE,SC_EPILOGUE>
 465 {
 466   "'" {
 467     STRING_GROW;
 468     context_state = YY_START;
 469     token_start = loc->start;
 470     BEGIN SC_CHARACTER;
 471   }
 472   "\"" {
 473     STRING_GROW;
 474     context_state = YY_START;
 475     token_start = loc->start;
 476     BEGIN SC_STRING;
 477   }
 478   "/"{splice}"*" {
 479     STRING_GROW;
 480     context_state = YY_START;
 481     token_start = loc->start;
 482     BEGIN SC_COMMENT;
 483   }
 484   "/"{splice}"/" {
 485     STRING_GROW;
 486     context_state = YY_START;
 487     BEGIN SC_LINE_COMMENT;
 488   }
 489 }
 490
 491
 492
 493   /*-----------------------------------------------------------.
 494   | Scanning some code in braces (actions). The initial "{" is |
 495   | already eaten.                                             |
 496   `-----------------------------------------------------------*/
 497
 498 <SC_BRACED_CODE>
 499 {
 500   "{"|"<"{splice}"%"  STRING_GROW; braces_level++;
 501   "%"{splice}">"      STRING_GROW; braces_level--;
 502   "}" {
 503     obstack_1grow (&obstack_for_string, '}');
 504
 505     --braces_level;
 506     if (braces_level < 0)
 507       {
 508         STRING_FINISH;
 509         loc->start = code_start;
 510         val->chars = last_string;
 511         gram_last_braced_code_loc = *loc;
 512         BEGIN INITIAL;
 513         return BRACED_CODE;
 514       }
 515   }
 516
 517   /* Tokenize `<<%' correctly (as `<<' `%') rather than incorrrectly
 518      (as `<' `<%').  */
 519   "<"{splice}"<"  STRING_GROW;
 520
 521   <<EOF>>  unexpected_eof (code_start, "}"); BEGIN INITIAL;
 522 }
 523
 524
 525   /*--------------------------------------------------------------.
 526   | Scanning some prologue: from "%{" (already scanned) to "%}".  |
 527   `--------------------------------------------------------------*/
 528
 529 <SC_PROLOGUE>
 530 {
 531   "%}" {
 532     STRING_FINISH;
 533     loc->start = code_start;
 534     val->chars = last_string;
 535     BEGIN INITIAL;
 536     return PROLOGUE;
 537   }
 538
 539   <<EOF>>  unexpected_eof (code_start, "%}"); BEGIN INITIAL;
 540 }
 541
 542
 543   /*---------------------------------------------------------------.
 544   | Scanning the epilogue (everything after the second "%%", which |
 545   | has already been eaten).                                       |
 546   `---------------------------------------------------------------*/
 547
 548 <SC_EPILOGUE>
 549 {
 550   <<EOF>> {
 551     STRING_FINISH;
 552     loc->start = code_start;
 553     val->chars = last_string;
 554     BEGIN INITIAL;
 555     return EPILOGUE;
 556   }
 557 }
 558
 559
 560   /*-----------------------------------------------------.
 561   | By default, grow the string obstack with the input.  |
 562   `-----------------------------------------------------*/
 563
 564 <SC_COMMENT,SC_LINE_COMMENT,SC_BRACED_CODE,SC_PROLOGUE,SC_EPILOGUE,SC_STRING,SC_CHARACTER,SC_ESCAPED_STRING,SC_ESCAPED_CHARACTER>.      |
 565 <SC_COMMENT,SC_LINE_COMMENT,SC_BRACED_CODE,SC_PROLOGUE,SC_EPILOGUE>\n   STRING_GROW;
 566
 567 %%
 568
 569 /* Read bytes from FP into buffer BUF of size SIZE.  Return the
 570    number of bytes read.  Remove '\r' from input, treating \r\n
 571    and isolated \r as \n.  */
 572
 573 static size_t
 574 no_cr_read (FILE *fp, char *buf, size_t size)
 575 {
 576   size_t bytes_read = fread (buf, 1, size, fp);
 577   if (bytes_read)
 578     {
 579       char *w = memchr (buf, '\r', bytes_read);
 580       if (w)
 581         {
 582           char const *r = ++w;
 583           char const *lim = buf + bytes_read;
 584
 585           for (;;)
 586             {
 587               /* Found an '\r'.  Treat it like '\n', but ignore any
 588                  '\n' that immediately follows.  */
 589               w[-1] = '\n';
 590               if (r == lim)
 591                 {
 592                   int ch = getc (fp);
 593                   if (ch != '\n' && ungetc (ch, fp) != ch)
 594                     break;
 595                 }
 596               else if (*r == '\n')
 597                 r++;
 598
 599               /* Copy until the next '\r'.  */
 600               do
 601                 {
 602                   if (r == lim)
 603                     return w - buf;
 604                 }
 605               while ((*w++ = *r++) != '\r');
 606             }
 607
 608           return w - buf;
 609         }
 610     }
 611
 612   return bytes_read;
 613 }
 614
 615
 616
 617 /*------------------------------------------------------.
 618 | Scan NUMBER for a base-BASE integer at location LOC.  |
 619 `------------------------------------------------------*/
 620
 621 static unsigned long int
 622 scan_integer (char const *number, int base, location loc)
 623 {
 624   verify (INT_MAX < ULONG_MAX);
 625   unsigned long int num = strtoul (number, NULL, base);
 626
 627   if (INT_MAX < num)
 628     {
 629       complain_at (loc, _("integer out of range: %s"), quote (number));
 630       num = INT_MAX;
 631     }
 632
 633   return num;
 634 }
 635
 636
 637 /*------------------------------------------------------------------.
 638 | Convert universal character name UCN to a single-byte character,  |
 639 | and return that character.  Return -1 if UCN does not correspond  |
 640 | to a single-byte character.                                       |
 641 `------------------------------------------------------------------*/
 642
 643 static int
 644 convert_ucn_to_byte (char const *ucn)
 645 {
 646   verify (UCHAR_MAX <= INT_MAX);
 647   unsigned long int code = strtoul (ucn + 2, NULL, 16);
 648
 649   /* FIXME: Currently we assume Unicode-compatible unibyte characters
 650      on ASCII hosts (i.e., Latin-1 on hosts with 8-bit bytes).  On
 651      non-ASCII hosts we support only the portable C character set.
 652      These limitations should be removed once we add support for
 653      multibyte characters.  */
 654
 655   if (UCHAR_MAX < code)
 656     return -1;
 657
 658 #if ! ('$' == 0x24 && '@' == 0x40 && '`' == 0x60 && '~' == 0x7e)
 659   {
 660     /* A non-ASCII host.  Use CODE to index into a table of the C
 661        basic execution character set, which is guaranteed to exist on
 662        all Standard C platforms.  This table also includes '$', '@',
 663        and '`', which are not in the basic execution character set but
 664        which are unibyte characters on all the platforms that we know
 665        about.  */
 666     static signed char const table[] =
 667       {
 668         '\0',   -1,   -1,   -1,   -1,   -1,   -1, '\a',
 669         '\b', '\t', '\n', '\v', '\f', '\r',   -1,   -1,
 670           -1,   -1,   -1,   -1,   -1,   -1,   -1,   -1,
 671           -1,   -1,   -1,   -1,   -1,   -1,   -1,   -1,
 672          ' ',  '!',  '"',  '#',  '$',  '%',  '&', '\'',
 673          '(',  ')',  '*',  '+',  ',',  '-',  '.',  '/',
 674          '0',  '1',  '2',  '3',  '4',  '5',  '6',  '7',
 675          '8',  '9',  ':',  ';',  '<',  '=',  '>',  '?',
 676          '@',  'A',  'B',  'C',  'D',  'E',  'F',  'G',
 677          'H',  'I',  'J',  'K',  'L',  'M',  'N',  'O',
 678          'P',  'Q',  'R',  'S',  'T',  'U',  'V',  'W',
 679          'X',  'Y',  'Z',  '[', '\\',  ']',  '^',  '_',
 680          '`',  'a',  'b',  'c',  'd',  'e',  'f',  'g',
 681          'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o',
 682          'p',  'q',  'r',  's',  't',  'u',  'v',  'w',
 683          'x',  'y',  'z',  '{',  '|',  '}',  '~'
 684       };
 685
 686     code = code < sizeof table ? table[code] : -1;
 687   }
 688 #endif
 689
 690   return code;
 691 }
 692
 693
 694 /*----------------------------------------------------------------.
 695 | Handle `#line INT "FILE"'.  ARGS has already skipped `#line '.  |
 696 `----------------------------------------------------------------*/
 697
 698 static void
 699 handle_syncline (char *args, location loc)
 700 {
 701   char *after_num;
 702   unsigned long int lineno = strtoul (args, &after_num, 10);
 703   char *file = strchr (after_num, '"') + 1;
 704   *strchr (file, '"') = '\0';
 705   if (INT_MAX <= lineno)
 706     {
 707       warn_at (loc, _("line number overflow"));
 708       lineno = INT_MAX;
 709     }
 710   current_file = uniqstr_new (file);
 711   boundary_set (&scanner_cursor, current_file, lineno, 1);
 712 }
 713
 714
 715 /*----------------------------------------------------------------.
 716 | For a token or comment starting at START, report message MSGID, |
 717 | which should say that an end marker was found before            |
 718 | the expected TOKEN_END.                                         |
 719 `----------------------------------------------------------------*/
 720
 721 static void
 722 unexpected_end (boundary start, char const *msgid, char const *token_end)
 723 {
 724   location loc;
 725   loc.start = start;
 726   loc.end = scanner_cursor;
 727   complain_at (loc, _(msgid), token_end);
 728 }
 729
 730
 731 /*------------------------------------------------------------------------.
 732 | Report an unexpected EOF in a token or comment starting at START.       |
 733 | An end of file was encountered and the expected TOKEN_END was missing.  |
 734 `------------------------------------------------------------------------*/
 735
 736 static void
 737 unexpected_eof (boundary start, char const *token_end)
 738 {
 739   unexpected_end (start, N_("missing `%s' at end of file"), token_end);
 740 }
 741
 742
 743 /*----------------------------------------.
 744 | Likewise, but for unexpected newlines.  |
 745 `----------------------------------------*/
 746
 747 static void
 748 unexpected_newline (boundary start, char const *token_end)
 749 {
 750   unexpected_end (start, N_("missing `%s' at end of line"), token_end);
 751 }
 752
 753
 754 /*-------------------------.
 755 | Initialize the scanner.  |
 756 `-------------------------*/
 757
 758 void
 759 gram_scanner_initialize (void)
 760 {
 761   obstack_init (&obstack_for_string);
 762 }
 763
 764
 765 /*-----------------------------------------------.
 766 | Free all the memory allocated to the scanner.  |
 767 `-----------------------------------------------*/
 768
 769 void
 770 gram_scanner_free (void)
 771 {
 772   obstack_free (&obstack_for_string, 0);
 773   /* Reclaim Flex's buffers.  */
 774   yy_delete_buffer (YY_CURRENT_BUFFER);
 775 }