src/scan-gram.l

   1 /* Bison Grammar Scanner                             -*- C -*-
   2
   3    Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation,
   4    Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    This program is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  20
  21 %option debug nodefault nounput noyywrap never-interactive
  22 %option prefix="gram_" outfile="lex.yy.c"
  23
  24 %{
  25 /* Work around a bug in flex 2.5.31.  See Debian bug 333231
  26    <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=333231>.  */
  27 #undef gram_wrap
  28 #define gram_wrap() 1
  29
  30 #define FLEX_PREFIX(Id) gram_ ## Id
  31 #include "flex-scanner.h"
  32
  33 #include "complain.h"
  34 #include "files.h"
  35 #include "gram.h"
  36 #include "quotearg.h"
  37 #include "reader.h"
  38 #include "uniqstr.h"
  39
  40 #include <mbswidth.h>
  41 #include <quote.h>
  42
  43 #include "scan-gram.h"
  44
  45 #define YY_DECL GRAM_LEX_DECL
  46
  47 #define YY_USER_INIT                                    \
  48    code_start = scanner_cursor = loc->start;            \
  49
  50 /* Location of scanner cursor.  */
  51 static boundary scanner_cursor;
  52
  53 #define YY_USER_ACTION  location_compute (loc, &scanner_cursor, yytext, yyleng);
  54
  55 static size_t no_cr_read (FILE *, char *, size_t);
  56 #define YY_INPUT(buf, result, size) ((result) = no_cr_read (yyin, buf, size))
  57
  58 /* A string representing the most recently saved token.  */
  59 static char *last_string;
  60
  61 void
  62 gram_scanner_last_string_free (void)
  63 {
  64   STRING_FREE;
  65 }
  66
  67 static void handle_syncline (char *, location);
  68 static unsigned long int scan_integer (char const *p, int base, location loc);
  69 static int convert_ucn_to_byte (char const *hex_text);
  70 static void unexpected_eof (boundary, char const *);
  71 static void unexpected_newline (boundary, char const *);
  72
  73 %}
  74  /* A C-like comment in directives/rules. */
  75 %x SC_YACC_COMMENT
  76  /* Strings and characters in directives/rules. */
  77 %x SC_ESCAPED_STRING SC_ESCAPED_CHARACTER
  78  /* A identifier was just read in directives/rules.  Special state
  79     to capture the sequence `identifier :'. */
  80 %x SC_AFTER_IDENTIFIER
  81
  82  /* Three types of user code:
  83     - prologue (code between `%{' `%}' in the first section, before %%);
  84     - actions, printers, union, etc, (between braced in the middle section);
  85     - epilogue (everything after the second %%). */
  86 %x SC_PROLOGUE SC_BRACED_CODE SC_EPILOGUE
  87  /* C and C++ comments in code. */
  88 %x SC_COMMENT SC_LINE_COMMENT
  89  /* Strings and characters in code. */
  90 %x SC_STRING SC_CHARACTER
  91
  92 letter    [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
  93 id        {letter}({letter}|[0-9])*
  94 directive %{letter}({letter}|[0-9]|-)*
  95 int       [0-9]+
  96
  97 /* POSIX says that a tag must be both an id and a C union member, but
  98    historically almost any character is allowed in a tag.  We disallow
  99    NUL and newline, as this simplifies our implementation.  */
 100 tag      [^\0\n>]+
 101
 102 /* Zero or more instances of backslash-newline.  Following GCC, allow
 103    white space between the backslash and the newline.  */
 104 splice   (\\[ \f\t\v]*\n)*
 105
 106 %%
 107 %{
 108   /* Nesting level of the current code in braces.  */
 109   int braces_level IF_LINT (= 0);
 110
 111   /* Parent context state, when applicable.  */
 112   int context_state IF_LINT (= 0);
 113
 114   /* Location of most recent identifier, when applicable.  */
 115   location id_loc IF_LINT (= empty_location);
 116
 117   /* Where containing code started, when applicable.  Its initial
 118      value is relevant only when yylex is invoked in the SC_EPILOGUE
 119      start condition.  */
 120   boundary code_start = scanner_cursor;
 121
 122   /* Where containing comment or string or character literal started,
 123      when applicable.  */
 124   boundary token_start IF_LINT (= scanner_cursor);
 125 %}
 126
 127
 128   /*-----------------------.
 129   | Scanning white space.  |
 130   `-----------------------*/
 131
 132 <INITIAL,SC_AFTER_IDENTIFIER>
 133 {
 134   /* Comments and white space.  */
 135   ","          warn_at (*loc, _("stray `,' treated as white space"));
 136   [ \f\n\t\v]  |
 137   "//".*       ;
 138   "/*" {
 139     token_start = loc->start;
 140     context_state = YY_START;
 141     BEGIN SC_YACC_COMMENT;
 142   }
 143
 144   /* #line directives are not documented, and may be withdrawn or
 145      modified in future versions of Bison.  */
 146   ^"#line "{int}" \"".*"\"\n" {
 147     handle_syncline (yytext + sizeof "#line " - 1, *loc);
 148   }
 149 }
 150
 151
 152   /*----------------------------.
 153   | Scanning Bison directives.  |
 154   `----------------------------*/
 155 <INITIAL>
 156 {
 157   "%binary"                         return PERCENT_NONASSOC;
 158   "%code"                           return PERCENT_CODE;
 159   "%debug"                          return PERCENT_DEBUG;
 160   "%default"[-_]"prec"              return PERCENT_DEFAULT_PREC;
 161   "%define"                         return PERCENT_DEFINE;
 162   "%defines"                        return PERCENT_DEFINES;
 163   "%destructor"                     return PERCENT_DESTRUCTOR;
 164   "%dprec"                          return PERCENT_DPREC;
 165   "%error"[-_]"verbose"             return PERCENT_ERROR_VERBOSE;
 166   "%expect"                         return PERCENT_EXPECT;
 167   "%expect"[-_]"rr"                 return PERCENT_EXPECT_RR;
 168   "%file-prefix"                    return PERCENT_FILE_PREFIX;
 169   "%fixed"[-_]"output"[-_]"files"   return PERCENT_YACC;
 170   "%initial-action"                 return PERCENT_INITIAL_ACTION;
 171   "%glr-parser"                     return PERCENT_GLR_PARSER;
 172   "%language"                       return PERCENT_LANGUAGE;
 173   "%left"                           return PERCENT_LEFT;
 174   "%lex-param"                      return PERCENT_LEX_PARAM;
 175   "%locations"                      return PERCENT_LOCATIONS;
 176   "%merge"                          return PERCENT_MERGE;
 177   "%name"[-_]"prefix"               return PERCENT_NAME_PREFIX;
 178   "%no"[-_]"default"[-_]"prec"      return PERCENT_NO_DEFAULT_PREC;
 179   "%no"[-_]"lines"                  return PERCENT_NO_LINES;
 180   "%nonassoc"                       return PERCENT_NONASSOC;
 181   "%nondeterministic-parser"        return PERCENT_NONDETERMINISTIC_PARSER;
 182   "%nterm"                          return PERCENT_NTERM;
 183   "%output"                         return PERCENT_OUTPUT;
 184   "%parse-param"                    return PERCENT_PARSE_PARAM;
 185   "%prec"                           return PERCENT_PREC;
 186   "%printer"                        return PERCENT_PRINTER;
 187   "%pure"[-_]"parser"               return PERCENT_PURE_PARSER;
 188   "%push-parser"                    return PERCENT_PUSH_PARSER;
 189   "%push-pull-parser"               return PERCENT_PUSH_PULL_PARSER;
 190   "%require"                        return PERCENT_REQUIRE;
 191   "%right"                          return PERCENT_RIGHT;
 192   "%skeleton"                       return PERCENT_SKELETON;
 193   "%start"                          return PERCENT_START;
 194   "%term"                           return PERCENT_TOKEN;
 195   "%token"                          return PERCENT_TOKEN;
 196   "%token"[-_]"table"               return PERCENT_TOKEN_TABLE;
 197   "%type"                           return PERCENT_TYPE;
 198   "%union"                          return PERCENT_UNION;
 199   "%verbose"                        return PERCENT_VERBOSE;
 200   "%yacc"                           return PERCENT_YACC;
 201
 202   {directive} {
 203     complain_at (*loc, _("invalid directive: %s"), quote (yytext));
 204   }
 205
 206   "="                     return EQUAL;
 207   "|"                     return PIPE;
 208   ";"                     return SEMICOLON;
 209   "<*>"                   return TYPE_TAG_ANY;
 210   "<>"                    return TYPE_TAG_NONE;
 211
 212   {id} {
 213     val->uniqstr = uniqstr_new (yytext);
 214     id_loc = *loc;
 215     BEGIN SC_AFTER_IDENTIFIER;
 216   }
 217
 218   {int} {
 219     val->integer = scan_integer (yytext, 10, *loc);
 220     return INT;
 221   }
 222   0[xX][0-9abcdefABCDEF]+ {
 223     val->integer = scan_integer (yytext, 16, *loc);
 224     return INT;
 225   }
 226
 227   /* Characters.  We don't check there is only one.  */
 228   "'"         STRING_GROW; token_start = loc->start; BEGIN SC_ESCAPED_CHARACTER;
 229
 230   /* Strings. */
 231   "\""        token_start = loc->start; BEGIN SC_ESCAPED_STRING;
 232
 233   /* Prologue. */
 234   "%{"        code_start = loc->start; BEGIN SC_PROLOGUE;
 235
 236   /* Code in between braces.  */
 237   "{" {
 238     STRING_GROW;
 239     braces_level = 0;
 240     code_start = loc->start;
 241     BEGIN SC_BRACED_CODE;
 242   }
 243
 244   /* A type. */
 245   "<"{tag}">" {
 246     obstack_grow (&obstack_for_string, yytext + 1, yyleng - 2);
 247     STRING_FINISH;
 248     val->uniqstr = uniqstr_new (last_string);
 249     STRING_FREE;
 250     return TYPE;
 251   }
 252
 253   "%%" {
 254     static int percent_percent_count;
 255     if (++percent_percent_count == 2)
 256       BEGIN SC_EPILOGUE;
 257     return PERCENT_PERCENT;
 258   }
 259
 260   . {
 261     complain_at (*loc, _("invalid character: %s"), quote (yytext));
 262   }
 263
 264   <<EOF>> {
 265     loc->start = loc->end = scanner_cursor;
 266     yyterminate ();
 267   }
 268 }
 269
 270
 271   /*-----------------------------------------------------------------.
 272   | Scanning after an identifier, checking whether a colon is next.  |
 273   `-----------------------------------------------------------------*/
 274
 275 <SC_AFTER_IDENTIFIER>
 276 {
 277   ":" {
 278     *loc = id_loc;
 279     BEGIN INITIAL;
 280     return ID_COLON;
 281   }
 282   . {
 283     scanner_cursor.column -= mbsnwidth (yytext, yyleng, 0);
 284     yyless (0);
 285     *loc = id_loc;
 286     BEGIN INITIAL;
 287     return ID;
 288   }
 289   <<EOF>> {
 290     *loc = id_loc;
 291     BEGIN INITIAL;
 292     return ID;
 293   }
 294 }
 295
 296
 297   /*---------------------------------------------------------------.
 298   | Scanning a Yacc comment.  The initial `/ *' is already eaten.  |
 299   `---------------------------------------------------------------*/
 300
 301 <SC_YACC_COMMENT>
 302 {
 303   "*/"     BEGIN context_state;
 304   .|\n     ;
 305   <<EOF>>  unexpected_eof (token_start, "*/"); BEGIN context_state;
 306 }
 307
 308
 309   /*------------------------------------------------------------.
 310   | Scanning a C comment.  The initial `/ *' is already eaten.  |
 311   `------------------------------------------------------------*/
 312
 313 <SC_COMMENT>
 314 {
 315   "*"{splice}"/"  STRING_GROW; BEGIN context_state;
 316   <<EOF>>         unexpected_eof (token_start, "*/"); BEGIN context_state;
 317 }
 318
 319
 320   /*--------------------------------------------------------------.
 321   | Scanning a line comment.  The initial `//' is already eaten.  |
 322   `--------------------------------------------------------------*/
 323
 324 <SC_LINE_COMMENT>
 325 {
 326   "\n"           STRING_GROW; BEGIN context_state;
 327   {splice}       STRING_GROW;
 328   <<EOF>>        BEGIN context_state;
 329 }
 330
 331
 332   /*------------------------------------------------.
 333   | Scanning a Bison string, including its escapes. |
 334   | The initial quote is already eaten.             |
 335   `------------------------------------------------*/
 336
 337 <SC_ESCAPED_STRING>
 338 {
 339   "\""|"\n" {
 340     if (yytext[0] == '\n')
 341       unexpected_newline (token_start, "\"");
 342     STRING_FINISH;
 343     loc->start = token_start;
 344     val->chars = last_string;
 345     BEGIN INITIAL;
 346     return STRING;
 347   }
 348   <<EOF>> {
 349     unexpected_eof (token_start, "\"");
 350     STRING_FINISH;
 351     loc->start = token_start;
 352     val->chars = last_string;
 353     BEGIN INITIAL;
 354     return STRING;
 355   }
 356 }
 357
 358   /*----------------------------------------------------------.
 359   | Scanning a Bison character literal, decoding its escapes. |
 360   | The initial quote is already eaten.                       |
 361   `----------------------------------------------------------*/
 362
 363 <SC_ESCAPED_CHARACTER>
 364 {
 365   "'"|"\n" {
 366     if (yytext[0] == '\n')
 367       unexpected_newline (token_start, "'");
 368     STRING_GROW;
 369     STRING_FINISH;
 370     loc->start = token_start;
 371     val->character = last_string[1];
 372     STRING_FREE;
 373     BEGIN INITIAL;
 374     return CHAR;
 375   }
 376   <<EOF>> {
 377     unexpected_eof (token_start, "'");
 378     STRING_FINISH;
 379     loc->start = token_start;
 380     if (strlen(last_string) > 1)
 381       val->character = last_string[1];
 382     else
 383       val->character = last_string[0];
 384     STRING_FREE;
 385     BEGIN INITIAL;
 386     return CHAR;
 387   }
 388 }
 389
 390 <SC_ESCAPED_CHARACTER,SC_ESCAPED_STRING>
 391 {
 392   \0        complain_at (*loc, _("invalid null character"));
 393 }
 394
 395
 396   /*----------------------------.
 397   | Decode escaped characters.  |
 398   `----------------------------*/
 399
 400 <SC_ESCAPED_STRING,SC_ESCAPED_CHARACTER>
 401 {
 402   \\[0-7]{1,3} {
 403     unsigned long int c = strtoul (yytext + 1, NULL, 8);
 404     if (UCHAR_MAX < c)
 405       complain_at (*loc, _("invalid escape sequence: %s"), quote (yytext));
 406     else if (! c)
 407       complain_at (*loc, _("invalid null character: %s"), quote (yytext));
 408     else
 409       obstack_1grow (&obstack_for_string, c);
 410   }
 411
 412   \\x[0-9abcdefABCDEF]+ {
 413     verify (UCHAR_MAX < ULONG_MAX);
 414     unsigned long int c = strtoul (yytext + 2, NULL, 16);
 415     if (UCHAR_MAX < c)
 416       complain_at (*loc, _("invalid escape sequence: %s"), quote (yytext));
 417     else if (! c)
 418       complain_at (*loc, _("invalid null character: %s"), quote (yytext));
 419     else
 420       obstack_1grow (&obstack_for_string, c);
 421   }
 422
 423   \\a   obstack_1grow (&obstack_for_string, '\a');
 424   \\b   obstack_1grow (&obstack_for_string, '\b');
 425   \\f   obstack_1grow (&obstack_for_string, '\f');
 426   \\n   obstack_1grow (&obstack_for_string, '\n');
 427   \\r   obstack_1grow (&obstack_for_string, '\r');
 428   \\t   obstack_1grow (&obstack_for_string, '\t');
 429   \\v   obstack_1grow (&obstack_for_string, '\v');
 430
 431   /* \\[\"\'?\\] would be shorter, but it confuses xgettext.  */
 432   \\("\""|"'"|"?"|"\\")  obstack_1grow (&obstack_for_string, yytext[1]);
 433
 434   \\(u|U[0-9abcdefABCDEF]{4})[0-9abcdefABCDEF]{4} {
 435     int c = convert_ucn_to_byte (yytext);
 436     if (c < 0)
 437       complain_at (*loc, _("invalid escape sequence: %s"), quote (yytext));
 438     else if (! c)
 439       complain_at (*loc, _("invalid null character: %s"), quote (yytext));
 440     else
 441       obstack_1grow (&obstack_for_string, c);
 442   }
 443   \\(.|\n)      {
 444     complain_at (*loc, _("unrecognized escape sequence: %s"), quote (yytext));
 445     STRING_GROW;
 446   }
 447 }
 448
 449   /*--------------------------------------------.
 450   | Scanning user-code characters and strings.  |
 451   `--------------------------------------------*/
 452
 453 <SC_CHARACTER,SC_STRING>
 454 {
 455   {splice}|\\{splice}[^\n\[\]]  STRING_GROW;
 456 }
 457
 458 <SC_CHARACTER>
 459 {
 460   "'"           STRING_GROW; BEGIN context_state;
 461   \n            unexpected_newline (token_start, "'"); BEGIN context_state;
 462   <<EOF>>       unexpected_eof (token_start, "'"); BEGIN context_state;
 463 }
 464
 465 <SC_STRING>
 466 {
 467   "\""          STRING_GROW; BEGIN context_state;
 468   \n            unexpected_newline (token_start, "\""); BEGIN context_state;
 469   <<EOF>>       unexpected_eof (token_start, "\""); BEGIN context_state;
 470 }
 471
 472
 473   /*---------------------------------------------------.
 474   | Strings, comments etc. can be found in user code.  |
 475   `---------------------------------------------------*/
 476
 477 <SC_BRACED_CODE,SC_PROLOGUE,SC_EPILOGUE>
 478 {
 479   "'" {
 480     STRING_GROW;
 481     context_state = YY_START;
 482     token_start = loc->start;
 483     BEGIN SC_CHARACTER;
 484   }
 485   "\"" {
 486     STRING_GROW;
 487     context_state = YY_START;
 488     token_start = loc->start;
 489     BEGIN SC_STRING;
 490   }
 491   "/"{splice}"*" {
 492     STRING_GROW;
 493     context_state = YY_START;
 494     token_start = loc->start;
 495     BEGIN SC_COMMENT;
 496   }
 497   "/"{splice}"/" {
 498     STRING_GROW;
 499     context_state = YY_START;
 500     BEGIN SC_LINE_COMMENT;
 501   }
 502 }
 503
 504
 505
 506   /*-----------------------------------------------------------.
 507   | Scanning some code in braces (actions). The initial "{" is |
 508   | already eaten.                                             |
 509   `-----------------------------------------------------------*/
 510
 511 <SC_BRACED_CODE>
 512 {
 513   "{"|"<"{splice}"%"  STRING_GROW; braces_level++;
 514   "%"{splice}">"      STRING_GROW; braces_level--;
 515   "}" {
 516     obstack_1grow (&obstack_for_string, '}');
 517
 518     --braces_level;
 519     if (braces_level < 0)
 520       {
 521         STRING_FINISH;
 522         loc->start = code_start;
 523         val->code = last_string;
 524         BEGIN INITIAL;
 525         return BRACED_CODE;
 526       }
 527   }
 528
 529   /* Tokenize `<<%' correctly (as `<<' `%') rather than incorrrectly
 530      (as `<' `<%').  */
 531   "<"{splice}"<"  STRING_GROW;
 532
 533   <<EOF>> {
 534     unexpected_eof (code_start, "}");
 535     STRING_FINISH;
 536     loc->start = code_start;
 537     val->code = last_string;
 538     BEGIN INITIAL;
 539     return BRACED_CODE;
 540   }
 541 }
 542
 543
 544   /*--------------------------------------------------------------.
 545   | Scanning some prologue: from "%{" (already scanned) to "%}".  |
 546   `--------------------------------------------------------------*/
 547
 548 <SC_PROLOGUE>
 549 {
 550   "%}" {
 551     STRING_FINISH;
 552     loc->start = code_start;
 553     val->chars = last_string;
 554     BEGIN INITIAL;
 555     return PROLOGUE;
 556   }
 557
 558   <<EOF>> {
 559     unexpected_eof (code_start, "%}");
 560     STRING_FINISH;
 561     loc->start = code_start;
 562     val->chars = last_string;
 563     BEGIN INITIAL;
 564     return PROLOGUE;
 565   }
 566 }
 567
 568
 569   /*---------------------------------------------------------------.
 570   | Scanning the epilogue (everything after the second "%%", which |
 571   | has already been eaten).                                       |
 572   `---------------------------------------------------------------*/
 573
 574 <SC_EPILOGUE>
 575 {
 576   <<EOF>> {
 577     STRING_FINISH;
 578     loc->start = code_start;
 579     val->chars = last_string;
 580     BEGIN INITIAL;
 581     return EPILOGUE;
 582   }
 583 }
 584
 585
 586   /*-----------------------------------------------------.
 587   | By default, grow the string obstack with the input.  |
 588   `-----------------------------------------------------*/
 589
 590 <SC_COMMENT,SC_LINE_COMMENT,SC_BRACED_CODE,SC_PROLOGUE,SC_EPILOGUE,SC_STRING,SC_CHARACTER,SC_ESCAPED_STRING,SC_ESCAPED_CHARACTER>.      |
 591 <SC_COMMENT,SC_LINE_COMMENT,SC_BRACED_CODE,SC_PROLOGUE,SC_EPILOGUE>\n   STRING_GROW;
 592
 593 %%
 594
 595 /* Read bytes from FP into buffer BUF of size SIZE.  Return the
 596    number of bytes read.  Remove '\r' from input, treating \r\n
 597    and isolated \r as \n.  */
 598
 599 static size_t
 600 no_cr_read (FILE *fp, char *buf, size_t size)
 601 {
 602   size_t bytes_read = fread (buf, 1, size, fp);
 603   if (bytes_read)
 604     {
 605       char *w = memchr (buf, '\r', bytes_read);
 606       if (w)
 607         {
 608           char const *r = ++w;
 609           char const *lim = buf + bytes_read;
 610
 611           for (;;)
 612             {
 613               /* Found an '\r'.  Treat it like '\n', but ignore any
 614                  '\n' that immediately follows.  */
 615               w[-1] = '\n';
 616               if (r == lim)
 617                 {
 618                   int ch = getc (fp);
 619                   if (ch != '\n' && ungetc (ch, fp) != ch)
 620                     break;
 621                 }
 622               else if (*r == '\n')
 623                 r++;
 624
 625               /* Copy until the next '\r'.  */
 626               do
 627                 {
 628                   if (r == lim)
 629                     return w - buf;
 630                 }
 631               while ((*w++ = *r++) != '\r');
 632             }
 633
 634           return w - buf;
 635         }
 636     }
 637
 638   return bytes_read;
 639 }
 640
 641
 642
 643 /*------------------------------------------------------.
 644 | Scan NUMBER for a base-BASE integer at location LOC.  |
 645 `------------------------------------------------------*/
 646
 647 static unsigned long int
 648 scan_integer (char const *number, int base, location loc)
 649 {
 650   verify (INT_MAX < ULONG_MAX);
 651   unsigned long int num = strtoul (number, NULL, base);
 652
 653   if (INT_MAX < num)
 654     {
 655       complain_at (loc, _("integer out of range: %s"), quote (number));
 656       num = INT_MAX;
 657     }
 658
 659   return num;
 660 }
 661
 662
 663 /*------------------------------------------------------------------.
 664 | Convert universal character name UCN to a single-byte character,  |
 665 | and return that character.  Return -1 if UCN does not correspond  |
 666 | to a single-byte character.                                       |
 667 `------------------------------------------------------------------*/
 668
 669 static int
 670 convert_ucn_to_byte (char const *ucn)
 671 {
 672   verify (UCHAR_MAX <= INT_MAX);
 673   unsigned long int code = strtoul (ucn + 2, NULL, 16);
 674
 675   /* FIXME: Currently we assume Unicode-compatible unibyte characters
 676      on ASCII hosts (i.e., Latin-1 on hosts with 8-bit bytes).  On
 677      non-ASCII hosts we support only the portable C character set.
 678      These limitations should be removed once we add support for
 679      multibyte characters.  */
 680
 681   if (UCHAR_MAX < code)
 682     return -1;
 683
 684 #if ! ('$' == 0x24 && '@' == 0x40 && '`' == 0x60 && '~' == 0x7e)
 685   {
 686     /* A non-ASCII host.  Use CODE to index into a table of the C
 687        basic execution character set, which is guaranteed to exist on
 688        all Standard C platforms.  This table also includes '$', '@',
 689        and '`', which are not in the basic execution character set but
 690        which are unibyte characters on all the platforms that we know
 691        about.  */
 692     static signed char const table[] =
 693       {
 694         '\0',   -1,   -1,   -1,   -1,   -1,   -1, '\a',
 695         '\b', '\t', '\n', '\v', '\f', '\r',   -1,   -1,
 696           -1,   -1,   -1,   -1,   -1,   -1,   -1,   -1,
 697           -1,   -1,   -1,   -1,   -1,   -1,   -1,   -1,
 698          ' ',  '!',  '"',  '#',  '$',  '%',  '&', '\'',
 699          '(',  ')',  '*',  '+',  ',',  '-',  '.',  '/',
 700          '0',  '1',  '2',  '3',  '4',  '5',  '6',  '7',
 701          '8',  '9',  ':',  ';',  '<',  '=',  '>',  '?',
 702          '@',  'A',  'B',  'C',  'D',  'E',  'F',  'G',
 703          'H',  'I',  'J',  'K',  'L',  'M',  'N',  'O',
 704          'P',  'Q',  'R',  'S',  'T',  'U',  'V',  'W',
 705          'X',  'Y',  'Z',  '[', '\\',  ']',  '^',  '_',
 706          '`',  'a',  'b',  'c',  'd',  'e',  'f',  'g',
 707          'h',  'i',  'j',  'k',  'l',  'm',  'n',  'o',
 708          'p',  'q',  'r',  's',  't',  'u',  'v',  'w',
 709          'x',  'y',  'z',  '{',  '|',  '}',  '~'
 710       };
 711
 712     code = code < sizeof table ? table[code] : -1;
 713   }
 714 #endif
 715
 716   return code;
 717 }
 718
 719
 720 /*----------------------------------------------------------------.
 721 | Handle `#line INT "FILE"'.  ARGS has already skipped `#line '.  |
 722 `----------------------------------------------------------------*/
 723
 724 static void
 725 handle_syncline (char *args, location loc)
 726 {
 727   char *after_num;
 728   unsigned long int lineno = strtoul (args, &after_num, 10);
 729   char *file = strchr (after_num, '"') + 1;
 730   *strchr (file, '"') = '\0';
 731   if (INT_MAX <= lineno)
 732     {
 733       warn_at (loc, _("line number overflow"));
 734       lineno = INT_MAX;
 735     }
 736   current_file = uniqstr_new (file);
 737   boundary_set (&scanner_cursor, current_file, lineno, 1);
 738 }
 739
 740
 741 /*----------------------------------------------------------------.
 742 | For a token or comment starting at START, report message MSGID, |
 743 | which should say that an end marker was found before            |
 744 | the expected TOKEN_END.                                         |
 745 `----------------------------------------------------------------*/
 746
 747 static void
 748 unexpected_end (boundary start, char const *msgid, char const *token_end)
 749 {
 750   location loc;
 751   loc.start = start;
 752   loc.end = scanner_cursor;
 753   complain_at (loc, _(msgid), token_end);
 754 }
 755
 756
 757 /*------------------------------------------------------------------------.
 758 | Report an unexpected EOF in a token or comment starting at START.       |
 759 | An end of file was encountered and the expected TOKEN_END was missing.  |
 760 `------------------------------------------------------------------------*/
 761
 762 static void
 763 unexpected_eof (boundary start, char const *token_end)
 764 {
 765   unexpected_end (start, N_("missing `%s' at end of file"), token_end);
 766 }
 767
 768
 769 /*----------------------------------------.
 770 | Likewise, but for unexpected newlines.  |
 771 `----------------------------------------*/
 772
 773 static void
 774 unexpected_newline (boundary start, char const *token_end)
 775 {
 776   unexpected_end (start, N_("missing `%s' at end of line"), token_end);
 777 }
 778
 779
 780 /*-------------------------.
 781 | Initialize the scanner.  |
 782 `-------------------------*/
 783
 784 void
 785 gram_scanner_initialize (void)
 786 {
 787   obstack_init (&obstack_for_string);
 788 }
 789
 790
 791 /*-----------------------------------------------.
 792 | Free all the memory allocated to the scanner.  |
 793 `-----------------------------------------------*/
 794
 795 void
 796 gram_scanner_free (void)
 797 {
 798   obstack_free (&obstack_for_string, 0);
 799   /* Reclaim Flex's buffers.  */
 800   yylex_destroy ();
 801 }