src/scan-code.l

   1 /* Bison Action Scanner                             -*- C -*-
   2
   3    Copyright (C) 2006, 2007, 2008, 2009 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 3 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, see <http://www.gnu.org/licenses/>.  */
  19
  20 %option debug nodefault noinput nounput noyywrap never-interactive
  21 %option prefix="code_" outfile="lex.yy.c"
  22
  23 %{
  24 /* Work around a bug in flex 2.5.31.  See Debian bug 333231
  25    <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=333231>.  */
  26 #undef code_wrap
  27 #define code_wrap() 1
  28
  29 #define FLEX_PREFIX(Id) code_ ## Id
  30 #include <src/flex-scanner.h>
  31
  32 #include <src/complain.h>
  33 #include <src/reader.h>
  34 #include <src/getargs.h>
  35 #include <src/muscle-tab.h>
  36 #include <src/scan-code.h>
  37 #include <src/symlist.h>
  38
  39 #include <c-ctype.h>
  40 #include <get-errno.h>
  41 #include <quote.h>
  42
  43 /* The current calling start condition: SC_RULE_ACTION or
  44    SC_SYMBOL_ACTION. */
  45 # define YY_DECL static char *code_lex (code_props *self, int sc_context)
  46 YY_DECL;
  47
  48 #define YY_USER_ACTION  location_compute (loc, &loc->end, yytext, yyleng);
  49
  50 static void handle_action_dollar (symbol_list *rule, char *cp,
  51                                   location dollar_loc);
  52 static void handle_action_at (symbol_list *rule, char *cp, location at_loc);
  53
  54 /* A string to be pushed to obstack after dollar/at has been handled. */
  55 static char *ref_tail_fields;
  56
  57 static location the_location;
  58 static location *loc = &the_location;
  59
  60 /* A string representing the most recent translation.  */
  61 static char *last_string;
  62
  63 /* True if an untyped $$ or $n was seen.  */
  64 static bool untyped_var_seen;
  65
  66 %}
  67  /* C and C++ comments in code. */
  68 %x SC_COMMENT SC_LINE_COMMENT
  69  /* Strings and characters in code. */
  70 %x SC_STRING SC_CHARACTER
  71  /* Whether in a rule or symbol action.  Specifies the translation
  72     of $ and @.  */
  73 %x SC_RULE_ACTION SC_SYMBOL_ACTION
  74
  75
  76 /* POSIX says that a tag must be both an id and a C union member, but
  77    historically almost any character is allowed in a tag.  We disallow
  78    NUL and newline, as this simplifies our implementation.  */
  79 tag      [^\0\n>]+
  80
  81 /* Zero or more instances of backslash-newline.  Following GCC, allow
  82    white space between the backslash and the newline.  */
  83 splice   (\\[ \f\t\v]*\n)*
  84
  85 /* C style identifier. Must start with letter. Will be used for
  86    named symbol references. Shall be kept synchronized with
  87    scan-gram.l "letter" and "id". */
  88 letter    [-.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
  89 id        {letter}({letter}|[0-9])*
  90 ref      -?[0-9]+|{id}|"["{id}"]"|"$"
  91
  92 %%
  93
  94 %{
  95   /* Nesting level of the current code in braces.  */
  96   int braces_level = 0;
  97
  98   /* Whether a semicolon is probably needed.
  99      The heuristic is that a semicolon is not needed after `{', `}', `;',
 100      or a C preprocessor directive, and that whitespaces and comments
 101      do not affect this flag.
 102      Note that `{' does not need a semicolon because of `{}'.
 103      A semicolon may be needed before a cpp direcive, but don't bother.  */
 104   bool need_semicolon = false;
 105
 106   /* Whether in a C preprocessor directive.  Don't use a start condition
 107      for this because, at the end of strings and comments, we still need
 108      to know whether we're in a directive.  */
 109   bool in_cpp = false;
 110
 111   /* This scanner is special: it is invoked only once, henceforth
 112      is expected to return only once.  This initialization is
 113      therefore done once per action to translate. */
 114   aver (sc_context == SC_SYMBOL_ACTION
 115         || sc_context == SC_RULE_ACTION
 116         || sc_context == INITIAL);
 117   BEGIN sc_context;
 118 %}
 119
 120   /*------------------------------------------------------------.
 121   | Scanning a C comment.  The initial `/ *' is already eaten.  |
 122   `------------------------------------------------------------*/
 123
 124 <SC_COMMENT>
 125 {
 126   "*"{splice}"/"  STRING_GROW; BEGIN sc_context;
 127 }
 128
 129
 130   /*--------------------------------------------------------------.
 131   | Scanning a line comment.  The initial `//' is already eaten.  |
 132   `--------------------------------------------------------------*/
 133
 134 <SC_LINE_COMMENT>
 135 {
 136   "\n"           STRING_GROW; BEGIN sc_context;
 137   {splice}       STRING_GROW;
 138 }
 139
 140
 141   /*--------------------------------------------.
 142   | Scanning user-code characters and strings.  |
 143   `--------------------------------------------*/
 144
 145 <SC_CHARACTER,SC_STRING>
 146 {
 147   {splice}|\\{splice}.  STRING_GROW;
 148 }
 149
 150 <SC_CHARACTER>
 151 {
 152   "'"           STRING_GROW; BEGIN sc_context;
 153 }
 154
 155 <SC_STRING>
 156 {
 157   "\""          STRING_GROW; BEGIN sc_context;
 158 }
 159
 160
 161 <SC_RULE_ACTION,SC_SYMBOL_ACTION>{
 162   "'" {
 163     STRING_GROW;
 164     BEGIN SC_CHARACTER;
 165     need_semicolon = true;
 166   }
 167   "\"" {
 168     STRING_GROW;
 169     BEGIN SC_STRING;
 170     need_semicolon = true;
 171   }
 172   "/"{splice}"*" {
 173     STRING_GROW;
 174     BEGIN SC_COMMENT;
 175   }
 176   "/"{splice}"/" {
 177     STRING_GROW;
 178     BEGIN SC_LINE_COMMENT;
 179   }
 180 }
 181
 182 <SC_RULE_ACTION>
 183 {
 184   "$"("<"{tag}">")?{ref}  {
 185     ref_tail_fields = 0;
 186     handle_action_dollar (self->rule, yytext, *loc);
 187     if (ref_tail_fields) {
 188       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 189     }
 190     need_semicolon = true;
 191   }
 192   "@"{ref} {
 193     ref_tail_fields = 0;
 194     handle_action_at (self->rule, yytext, *loc);
 195     if (ref_tail_fields) {
 196       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 197     }
 198     need_semicolon = true;
 199   }
 200   "$"  {
 201     warn_at (*loc, _("stray `$'"));
 202     obstack_sgrow (&obstack_for_string, "$][");
 203     need_semicolon = true;
 204   }
 205   "@"  {
 206     warn_at (*loc, _("stray `@'"));
 207     obstack_sgrow (&obstack_for_string, "@@");
 208     need_semicolon = true;
 209   }
 210   "["  {
 211     obstack_sgrow (&obstack_for_string, "@{");
 212     need_semicolon = true;
 213   }
 214   "]"  {
 215     obstack_sgrow (&obstack_for_string, "@}");
 216     need_semicolon = true;
 217   }
 218
 219   ";"  STRING_GROW;                 need_semicolon = false;
 220   "{"  STRING_GROW; ++braces_level; need_semicolon = false;
 221   "}"  {
 222     bool outer_brace = --braces_level == 0;
 223
 224     /* As an undocumented Bison extension, append `;' before the last
 225        brace in braced code, so that the user code can omit trailing
 226        `;'.  But do not append `;' if emulating Yacc, since Yacc does
 227        not append one.  */
 228     if (outer_brace && !yacc_flag && language_prio == default_prio
 229         && skeleton_prio == default_prio && need_semicolon && ! in_cpp)
 230       {
 231         warn_at (*loc, _("a `;' might be needed at the end of action code"));
 232         warn_at (*loc, _("future versions of Bison will not add the `;'"));
 233         obstack_1grow (&obstack_for_string, ';');
 234       }
 235
 236     STRING_GROW;
 237     need_semicolon = false;
 238   }
 239
 240   /* Preprocessing directives should only be recognized at the beginning
 241      of lines, allowing whitespace including comments, but in C/C++,
 242      `#' can only be the start of preprocessor directives or within
 243      `#define' directives anyway, so don't bother with begin of line.  */
 244   "#"       STRING_GROW; in_cpp = true;
 245
 246   {splice}  STRING_GROW;
 247   [\n\r]    STRING_GROW; if (in_cpp) in_cpp = need_semicolon = false;
 248   [ \t\f]   STRING_GROW;
 249   .         STRING_GROW; need_semicolon = true;
 250 }
 251
 252 <SC_SYMBOL_ACTION>
 253 {
 254   "$$" {
 255     obstack_sgrow (&obstack_for_string, "]b4_dollar_dollar[");
 256     self->is_value_used = true;
 257   }
 258   "@$" {
 259     obstack_sgrow (&obstack_for_string, "]b4_at_dollar[");
 260     muscle_percent_define_ensure("locations", the_location, true);
 261   }
 262 }
 263
 264
 265   /*-----------------------------------------.
 266   | Escape M4 quoting characters in C code.  |
 267   `-----------------------------------------*/
 268
 269 <*>
 270 {
 271   \$    obstack_sgrow (&obstack_for_string, "$][");
 272   \@    obstack_sgrow (&obstack_for_string, "@@");
 273   \[    obstack_sgrow (&obstack_for_string, "@{");
 274   \]    obstack_sgrow (&obstack_for_string, "@}");
 275 }
 276
 277   /*-----------------------------------------------------.
 278   | By default, grow the string obstack with the input.  |
 279   `-----------------------------------------------------*/
 280
 281 <*>.|\n STRING_GROW;
 282
 283  /* End of processing. */
 284 <*><<EOF>>       {
 285                    STRING_FINISH;
 286                    return last_string;
 287                  }
 288
 289 %%
 290
 291 static inline bool
 292 is_dot_or_dash (char ch)
 293 {
 294   return ch == '.' || ch == '-';
 295 }
 296
 297 static inline bool
 298 contains_dot_or_dash (const char* p)
 299 {
 300   for (; *p; ++p)
 301     if (is_dot_or_dash (*p))
 302       return true;
 303   return false;
 304 }
 305
 306 /* Defines a variant of a symbolic name resolution. */
 307 typedef struct
 308 {
 309   /* Index in symbol list. */
 310   unsigned symbol_index;
 311
 312   /* Matched symbol id and loc. */
 313   uniqstr id;
 314   location loc;
 315
 316   /* Hiding named reference. */
 317   named_ref* hidden_by;
 318
 319   /* Error flags. May contain zero (no errors) or
 320      a combination of VARIANT_* values. */
 321   unsigned err;
 322 } variant;
 323
 324 /* Set when the variant refers to a symbol hidden
 325    by an explicit symbol reference. */
 326 #define VARIANT_HIDDEN (1 << 0)
 327
 328 /* Set when the variant refers to a symbol containing
 329    dots or dashes. Will require explicit bracketing. */
 330 #define VARIANT_BAD_BRACKETING (1 << 1)
 331
 332 /* Set when the variant refers to a symbol which is
 333    not visible from current midrule. */
 334 #define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
 335
 336 static variant *variant_table = 0;
 337 static unsigned variant_table_size = 0;
 338 static unsigned variant_count = 0;
 339
 340 static variant *
 341 variant_table_grow (void)
 342 {
 343   ++variant_count;
 344   if (variant_count > variant_table_size)
 345     {
 346       while (variant_count > variant_table_size)
 347         variant_table_size = 2 * variant_table_size + 3;
 348       variant_table = xnrealloc (variant_table, variant_table_size,
 349                                  sizeof *variant_table);
 350     }
 351   return &variant_table[variant_count - 1];
 352 }
 353
 354 static void
 355 variant_table_free (void)
 356 {
 357   free (variant_table);
 358   variant_table = 0;
 359   variant_table_size = variant_count = 0;
 360 }
 361
 362 static char *
 363 find_prefix_end (const char *prefix, char *begin, char *end)
 364 {
 365   char *ptr = begin;
 366
 367   for (; *prefix && ptr != end; ++prefix, ++ptr)
 368     if (*prefix != *ptr)
 369       return 0;
 370
 371   if (*prefix)
 372     return 0;
 373
 374   return ptr;
 375 }
 376
 377 static variant *
 378 variant_add (uniqstr id, location id_loc, unsigned symbol_index,
 379              char *cp, char *cp_end, bool exact_mode)
 380 {
 381   char *prefix_end;
 382
 383   prefix_end = find_prefix_end (id, cp, cp_end);
 384   if (prefix_end &&
 385       (prefix_end == cp_end ||
 386        (!exact_mode && is_dot_or_dash (*prefix_end))))
 387     {
 388       variant *r = variant_table_grow ();
 389       r->symbol_index = symbol_index;
 390       r->id = id;
 391       r->loc = id_loc;
 392       r->hidden_by = NULL;
 393       r->err = 0;
 394       return r;
 395     }
 396   else
 397     return NULL;
 398 }
 399
 400 static const char *
 401 get_at_spec(unsigned symbol_index)
 402 {
 403   static char at_buf[20];
 404   if (symbol_index == 0)
 405     strcpy (at_buf, "$$");
 406   else
 407     snprintf (at_buf, sizeof at_buf, "$%u", symbol_index);
 408   return at_buf;
 409 }
 410
 411 static void
 412 show_sub_messages (const char* cp, bool exact_mode, int midrule_rhs_index,
 413                    char dollar_or_at, bool is_warning)
 414 {
 415   unsigned i;
 416
 417   for (i = 0; i < variant_count; ++i)
 418     {
 419       const variant *var = &variant_table[i];
 420       const char *at_spec = get_at_spec (var->symbol_index);
 421
 422       if (var->err == 0)
 423         {
 424           if (is_warning)
 425             warn_at (var->loc, _("  refers to: %c%s at %s"),
 426                      dollar_or_at, var->id, at_spec);
 427           else
 428             complain_at (var->loc, _("  refers to: %c%s at %s"),
 429                          dollar_or_at, var->id, at_spec);
 430         }
 431       else
 432         {
 433           static struct obstack msg_buf;
 434           const char *tail = exact_mode ? "" :
 435             cp + strlen (var->id);
 436           const char *id = var->hidden_by ? var->hidden_by->id :
 437             var->id;
 438           location id_loc = var->hidden_by ? var->hidden_by->loc :
 439             var->loc;
 440
 441           /* Create the explanation message. */
 442           obstack_init (&msg_buf);
 443
 444           obstack_fgrow1 (&msg_buf, "  possibly meant: %c", dollar_or_at);
 445           if (contains_dot_or_dash (id))
 446             obstack_fgrow1 (&msg_buf, "[%s]", id);
 447           else
 448             obstack_sgrow (&msg_buf, id);
 449           obstack_sgrow (&msg_buf, tail);
 450
 451           if (var->err & VARIANT_HIDDEN)
 452             {
 453               obstack_fgrow1 (&msg_buf, ", hiding %c", dollar_or_at);
 454               if (contains_dot_or_dash (var->id))
 455                 obstack_fgrow1 (&msg_buf, "[%s]", var->id);
 456               else
 457                 obstack_sgrow (&msg_buf, var->id);
 458               obstack_sgrow (&msg_buf, tail);
 459             }
 460
 461           obstack_fgrow1 (&msg_buf, " at %s", at_spec);
 462
 463           if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
 464             obstack_fgrow1 (&msg_buf, ", cannot be accessed from "
 465                             "mid-rule action at $%d", midrule_rhs_index);
 466
 467           obstack_1grow (&msg_buf, '\0');
 468           if (is_warning)
 469             warn_at (id_loc, _("%s"), (char *) obstack_finish (&msg_buf));
 470           else
 471             complain_at (id_loc, _("%s"), (char *) obstack_finish (&msg_buf));
 472           obstack_free (&msg_buf, 0);
 473         }
 474     }
 475 }
 476
 477 /* Returned from "parse_ref" when the reference
 478    is inappropriate. */
 479 #define INVALID_REF (INT_MIN)
 480
 481 /* Returned from "parse_ref" when the reference
 482    points to LHS ($$) of the current rule or midrule. */
 483 #define LHS_REF (INT_MIN + 1)
 484
 485 /* Parse named or positional reference. In case of positional
 486    references, can return negative values for $-n "deep" stack
 487    accesses. */
 488 static long int
 489 parse_ref (char *cp, symbol_list *rule, int rule_length,
 490            int midrule_rhs_index, char *text, location text_loc,
 491            char dollar_or_at)
 492 {
 493   symbol_list *l;
 494   char *cp_end;
 495   bool exact_mode;
 496   unsigned i;
 497   unsigned valid_variants = 0;
 498   unsigned valid_variant_index = 0;
 499
 500   if ('$' == *cp)
 501     return LHS_REF;
 502
 503   if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))
 504     {
 505       long int num = strtol (cp, &cp, 10);
 506       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
 507         return num;
 508       else
 509         {
 510           complain_at (text_loc, _("integer out of range: %s"),
 511                        quote (text));
 512           return INVALID_REF;
 513         }
 514     }
 515
 516   if ('[' == *cp)
 517     {
 518       /* Ignore the brackets. */
 519       char *p;
 520       for (p = ++cp; *p != ']'; ++p)
 521         continue;
 522       cp_end = p;
 523
 524       exact_mode = true;
 525     }
 526   else
 527     {
 528       /* Take all characters of the name. */
 529       char* p;
 530       for (p = cp; *p; ++p)
 531         if (is_dot_or_dash (*p))
 532           {
 533             ref_tail_fields = p;
 534             break;
 535           }
 536       for (p = cp; *p; ++p)
 537         continue;
 538       cp_end = p;
 539
 540       exact_mode = false;
 541     }
 542
 543   /* Add all relevant variants. */
 544   {
 545     unsigned symbol_index;
 546     variant_count = 0;
 547     for (symbol_index = 0, l = rule; !symbol_list_null (l);
 548          ++symbol_index, l = l->next)
 549       {
 550         variant *var;
 551         if (l->content_type != SYMLIST_SYMBOL)
 552           continue;
 553
 554         var = variant_add (l->content.sym->tag, l->sym_loc,
 555                            symbol_index, cp, cp_end, exact_mode);
 556         if (var && l->named_ref)
 557           var->hidden_by = l->named_ref;
 558
 559         if (l->named_ref)
 560           variant_add (l->named_ref->id, l->named_ref->loc,
 561                        symbol_index, cp, cp_end, exact_mode);
 562       }
 563   }
 564
 565   /* Check errors. */
 566   for (i = 0; i < variant_count; ++i)
 567     {
 568       variant *var = &variant_table[i];
 569       unsigned symbol_index = var->symbol_index;
 570
 571       /* Check visibility from mid-rule actions. */
 572       if (midrule_rhs_index != 0
 573           && (symbol_index == 0 || midrule_rhs_index < symbol_index))
 574         var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
 575
 576       /* Check correct bracketing. */
 577       if (!exact_mode && contains_dot_or_dash (var->id))
 578         var->err |= VARIANT_BAD_BRACKETING;
 579
 580       /* Check using of hidden symbols. */
 581       if (var->hidden_by)
 582         var->err |= VARIANT_HIDDEN;
 583
 584       if (!var->err)
 585         {
 586           valid_variant_index = i;
 587           ++valid_variants;
 588         }
 589     }
 590
 591   switch (valid_variants)
 592     {
 593     case 0:
 594       if (variant_count == 0)
 595         complain_at (text_loc, _("invalid reference: %s, symbol not found"),
 596                      quote (text));
 597       else
 598         {
 599           complain_at (text_loc, _("invalid reference: %s"),
 600                        quote (text));
 601           show_sub_messages (cp, exact_mode, midrule_rhs_index,
 602                              dollar_or_at, false);
 603         }
 604       return INVALID_REF;
 605     case 1:
 606       {
 607         if (variant_count > 1)
 608           {
 609             warn_at (text_loc, _("misleading reference: %s"),
 610                      quote (text));
 611             show_sub_messages (cp, exact_mode, midrule_rhs_index,
 612                                dollar_or_at, true);
 613           }
 614         {
 615           unsigned symbol_index =
 616             variant_table[valid_variant_index].symbol_index;
 617           return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
 618         }
 619       }
 620     case 2:
 621     default:
 622       complain_at (text_loc, _("ambiguous reference: %s"),
 623                    quote (text));
 624       show_sub_messages (cp, exact_mode, midrule_rhs_index,
 625                          dollar_or_at, false);
 626       return INVALID_REF;
 627     }
 628
 629   /* Not reachable. */
 630   return INVALID_REF;
 631 }
 632
 633 /* Keeps track of the maximum number of semantic values to the left of
 634    a handle (those referenced by $0, $-1, etc.) are required by the
 635    semantic actions of this grammar. */
 636 int max_left_semantic_context = 0;
 637
 638
 639 /*------------------------------------------------------------------.
 640 | TEXT is pointing to a wannabee semantic value (i.e., a `$').      |
 641 |                                                                   |
 642 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 643 |                                                                   |
 644 | Output to OBSTACK_FOR_STRING a reference to this semantic value.  |
 645 `------------------------------------------------------------------*/
 646
 647 static void
 648 handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 649 {
 650   char const *type_name = NULL;
 651   char *cp = text + 1;
 652   char *gt_ptr = 0;
 653   symbol_list *effective_rule;
 654   int effective_rule_length;
 655   int n;
 656
 657   if (rule->midrule_parent_rule)
 658     {
 659       effective_rule = rule->midrule_parent_rule;
 660       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 661     }
 662   else
 663     {
 664       effective_rule = rule;
 665       effective_rule_length = symbol_list_length (rule->next);
 666     }
 667
 668   /* Get the type name if explicit. */
 669   if (*cp == '<')
 670     {
 671       type_name = ++cp;
 672       while (*cp != '>')
 673         ++cp;
 674
 675       /* The '>' symbol will be later replaced by '\0'. Original
 676          'text' is needed for error messages. */
 677       gt_ptr = cp;
 678       ++cp;
 679       if (untyped_var_seen)
 680         complain_at (dollar_loc, _("explicit type given in untyped grammar"));
 681       tag_seen = true;
 682     }
 683
 684   n = parse_ref (cp, effective_rule, effective_rule_length,
 685                  rule->midrule_parent_rhs_index, text, dollar_loc, '$');
 686
 687   if (gt_ptr)
 688     *gt_ptr = '\0';
 689
 690   switch (n)
 691     {
 692     case INVALID_REF:
 693       break;
 694
 695     case LHS_REF:
 696       if (!type_name)
 697         type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
 698
 699       if (!type_name)
 700         {
 701           if (union_seen | tag_seen)
 702             {
 703               if (rule->midrule_parent_rule)
 704                 complain_at (dollar_loc,
 705                              _("$$ for the midrule at $%d of `%s'"
 706                                " has no declared type"),
 707                              rule->midrule_parent_rhs_index,
 708                              effective_rule->content.sym->tag);
 709               else
 710                 complain_at (dollar_loc, _("$$ of `%s' has no declared type"),
 711                              rule->content.sym->tag);
 712             }
 713           else
 714             untyped_var_seen = true;
 715           type_name = "";
 716         }
 717
 718       obstack_fgrow1 (&obstack_for_string,
 719                       "]b4_lhs_value([%s])[", type_name);
 720       rule->action_props.is_value_used = true;
 721       break;
 722
 723     default:
 724       if (max_left_semantic_context < 1 - n)
 725         max_left_semantic_context = 1 - n;
 726       if (!type_name && 0 < n)
 727         type_name =
 728           symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
 729       if (!type_name)
 730         {
 731           if (union_seen | tag_seen)
 732             complain_at (dollar_loc, _("$%s of `%s' has no declared type"),
 733                          cp, effective_rule->content.sym->tag);
 734           else
 735             untyped_var_seen = true;
 736           type_name = "";
 737         }
 738
 739       obstack_fgrow3 (&obstack_for_string,
 740                       "]b4_rhs_value(%d, %d, [%s])[",
 741                       effective_rule_length, n, type_name);
 742       if (n > 0)
 743         symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
 744           true;
 745       break;
 746     }
 747 }
 748
 749
 750 /*------------------------------------------------------.
 751 | TEXT is a location token (i.e., a `@...').  Output to |
 752 | OBSTACK_FOR_STRING a reference to this location.      |
 753 `------------------------------------------------------*/
 754
 755 static void
 756 handle_action_at (symbol_list *rule, char *text, location at_loc)
 757 {
 758   char *cp = text + 1;
 759   symbol_list *effective_rule;
 760   int effective_rule_length;
 761   int n;
 762
 763   if (rule->midrule_parent_rule)
 764     {
 765       effective_rule = rule->midrule_parent_rule;
 766       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 767     }
 768   else
 769     {
 770       effective_rule = rule;
 771       effective_rule_length = symbol_list_length (rule->next);
 772     }
 773
 774   muscle_percent_define_ensure("locations", at_loc, true);
 775
 776   n = parse_ref (cp, effective_rule, effective_rule_length,
 777                        rule->midrule_parent_rhs_index, text, at_loc, '@');
 778   switch (n)
 779     {
 780     case INVALID_REF:
 781       break;
 782
 783     case LHS_REF:
 784       obstack_sgrow (&obstack_for_string, "]b4_lhs_location[");
 785       break;
 786
 787     default:
 788       obstack_fgrow2 (&obstack_for_string, "]b4_rhs_location(%d, %d)[",
 789                       effective_rule_length, n);
 790       break;
 791     }
 792 }
 793
 794
 795 /*-------------------------.
 796 | Initialize the scanner.  |
 797 `-------------------------*/
 798
 799 /* Translate the dollars and ats in \a self, in the context \a sc_context
 800    (SC_RULE_ACTION, SC_SYMBOL_ACTION, INITIAL).  */
 801
 802 static char const *
 803 translate_action (code_props *self, int sc_context)
 804 {
 805   char *res;
 806   static bool initialized = false;
 807   if (!initialized)
 808     {
 809       obstack_init (&obstack_for_string);
 810       yy_flex_debug = 0;
 811       initialized = true;
 812     }
 813
 814   loc->start = loc->end = self->location.start;
 815   yy_switch_to_buffer (yy_scan_string (self->code));
 816   res = code_lex (self, sc_context);
 817   yy_delete_buffer (YY_CURRENT_BUFFER);
 818
 819   return res;
 820 }
 821
 822 /*------------------------------------------------------------------------.
 823 | Implementation of the public interface as documented in "scan-code.h".  |
 824 `------------------------------------------------------------------------*/
 825
 826 void
 827 code_props_none_init (code_props *self)
 828 {
 829   *self = code_props_none;
 830 }
 831
 832 code_props const code_props_none = CODE_PROPS_NONE_INIT;
 833
 834 void
 835 code_props_plain_init (code_props *self, char const *code,
 836                        location code_loc)
 837 {
 838   self->kind = CODE_PROPS_PLAIN;
 839   self->code = code;
 840   self->location = code_loc;
 841   self->is_value_used = false;
 842   self->rule = NULL;
 843   self->named_ref = NULL;
 844 }
 845
 846 void
 847 code_props_symbol_action_init (code_props *self, char const *code,
 848                                location code_loc)
 849 {
 850   self->kind = CODE_PROPS_SYMBOL_ACTION;
 851   self->code = code;
 852   self->location = code_loc;
 853   self->is_value_used = false;
 854   self->rule = NULL;
 855   self->named_ref = NULL;
 856 }
 857
 858 void
 859 code_props_rule_action_init (code_props *self, char const *code,
 860                              location code_loc, symbol_list *rule,
 861                              named_ref *name)
 862 {
 863   self->kind = CODE_PROPS_RULE_ACTION;
 864   self->code = code;
 865   self->location = code_loc;
 866   self->is_value_used = false;
 867   self->rule = rule;
 868   self->named_ref = name;
 869 }
 870
 871 void
 872 code_props_translate_code (code_props *self)
 873 {
 874   switch (self->kind)
 875     {
 876       case CODE_PROPS_NONE:
 877         break;
 878       case CODE_PROPS_PLAIN:
 879         self->code = translate_action (self, INITIAL);
 880         break;
 881       case CODE_PROPS_SYMBOL_ACTION:
 882         self->code = translate_action (self, SC_SYMBOL_ACTION);
 883         break;
 884       case CODE_PROPS_RULE_ACTION:
 885         self->code = translate_action (self, SC_RULE_ACTION);
 886         break;
 887     }
 888 }
 889
 890 void
 891 code_scanner_last_string_free (void)
 892 {
 893   STRING_FREE;
 894 }
 895
 896 void
 897 code_scanner_free (void)
 898 {
 899   obstack_free (&obstack_for_string, 0);
 900   variant_table_free ();
 901
 902   /* Reclaim Flex's buffers.  */
 903   yylex_destroy ();
 904 }