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