src/scan-code.l

   1 /* Bison Action Scanner                             -*- C -*-
   2
   3    Copyright (C) 2006-2013 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 char *fetch_type_name (char *cp, char const **type_name,
  51                               location dollar_loc);
  52
  53 static void handle_action_dollar (symbol_list *rule, char *cp,
  54                                   location dollar_loc);
  55 static void handle_action_at (symbol_list *rule, char *cp, location at_loc);
  56
  57 /* A string to be pushed to obstack after dollar/at has been handled. */
  58 static char *ref_tail_fields;
  59
  60 static location the_location;
  61 static location *loc = &the_location;
  62
  63 /* A string representing the most recent translation.  */
  64 static char *last_string;
  65
  66 /* True if an untyped $$ or $n was seen.  */
  67 static bool untyped_var_seen;
  68
  69 %}
  70  /* C and C++ comments in code. */
  71 %x SC_COMMENT SC_LINE_COMMENT
  72  /* Strings and characters in code. */
  73 %x SC_STRING SC_CHARACTER
  74  /* Whether in a rule or symbol action.  Specifies the translation
  75     of $ and @.  */
  76 %x SC_RULE_ACTION SC_SYMBOL_ACTION
  77
  78
  79 /* POSIX says that a tag must be both an id and a C union member, but
  80    historically almost any character is allowed in a tag.  We disallow
  81    NUL and newline, as this simplifies our implementation.  We allow
  82    "->" as a means to dereference a pointer.  */
  83 tag      ([^\0\n>]|->)+
  84
  85 /* Zero or more instances of backslash-newline.  Following GCC, allow
  86    white space between the backslash and the newline.  */
  87 splice   (\\[ \f\t\v]*\n)*
  88
  89 /* C style identifier. Must start with letter. Will be used for
  90    named symbol references. Shall be kept synchronized with
  91    scan-gram.l "letter" and "id". */
  92 letter    [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
  93 id        {letter}({letter}|[-0-9])*
  94 ref      -?[0-9]+|{id}|"["{id}"]"|"$"
  95
  96 %%
  97
  98 %{
  99   /* This scanner is special: it is invoked only once, henceforth
 100      is expected to return only once.  This initialization is
 101      therefore done once per action to translate. */
 102   aver (sc_context == SC_SYMBOL_ACTION
 103         || sc_context == SC_RULE_ACTION
 104         || sc_context == INITIAL);
 105   BEGIN sc_context;
 106 %}
 107
 108   /*------------------------------------------------------------.
 109   | Scanning a C comment.  The initial '/ *' is already eaten.  |
 110   `------------------------------------------------------------*/
 111
 112 <SC_COMMENT>
 113 {
 114   "*"{splice}"/"  STRING_GROW; BEGIN sc_context;
 115 }
 116
 117
 118   /*--------------------------------------------------------------.
 119   | Scanning a line comment.  The initial '//' is already eaten.  |
 120   `--------------------------------------------------------------*/
 121
 122 <SC_LINE_COMMENT>
 123 {
 124   "\n"           STRING_GROW; BEGIN sc_context;
 125   {splice}       STRING_GROW;
 126 }
 127
 128
 129   /*--------------------------------------------.
 130   | Scanning user-code characters and strings.  |
 131   `--------------------------------------------*/
 132
 133 <SC_CHARACTER,SC_STRING>
 134 {
 135   {splice}|\\{splice}.  STRING_GROW;
 136 }
 137
 138 <SC_CHARACTER>
 139 {
 140   "'"           STRING_GROW; BEGIN sc_context;
 141 }
 142
 143 <SC_STRING>
 144 {
 145   "\""          STRING_GROW; BEGIN sc_context;
 146 }
 147
 148
 149 <SC_RULE_ACTION,SC_SYMBOL_ACTION>
 150 {
 151   "'"              STRING_GROW; BEGIN SC_CHARACTER;
 152   "\""             STRING_GROW; BEGIN SC_STRING;
 153   "/"{splice}"*"   STRING_GROW; BEGIN SC_COMMENT;
 154   "/"{splice}"/"   STRING_GROW; BEGIN SC_LINE_COMMENT;
 155
 156   [$@]  {
 157     complain (loc, Wother, _("stray '%s'"), yytext);
 158     obstack_escape (&obstack_for_string, yytext);
 159   }
 160 }
 161
 162 <SC_RULE_ACTION>
 163 {
 164   "$"("<"{tag}">")?{ref}  {
 165     ref_tail_fields = NULL;
 166     handle_action_dollar (self->rule, yytext, *loc);
 167     if (ref_tail_fields)
 168       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 169   }
 170   "@"{ref} {
 171     ref_tail_fields = NULL;
 172     handle_action_at (self->rule, yytext, *loc);
 173     if (ref_tail_fields)
 174       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 175   }
 176 }
 177
 178 <SC_SYMBOL_ACTION>
 179 {
 180   "$"("<"{tag}">")?"$" {
 181     const char *type_name = NULL;
 182     fetch_type_name (yytext + 1, &type_name, *loc)[-1] = 0;
 183     obstack_sgrow (&obstack_for_string, "]b4_dollar_dollar(");
 184     obstack_quote (&obstack_for_string, type_name);
 185     obstack_sgrow (&obstack_for_string, ")[");
 186     self->is_value_used = true;
 187   }
 188   "@$" {
 189     obstack_sgrow (&obstack_for_string, "]b4_at_dollar[");
 190     muscle_percent_define_ensure("locations", the_location, true);
 191   }
 192 }
 193
 194
 195 <*>
 196 {
 197   /* Escape M4 quoting characters in C code.  */
 198   [$@\[\]]    obstack_escape (&obstack_for_string, yytext);
 199
 200   /* By default, grow the string obstack with the input.  */
 201   .|\n        STRING_GROW;
 202
 203  /* End of processing. */
 204   <<EOF>>     STRING_FINISH; return last_string;
 205 }
 206
 207 %%
 208
 209 static inline bool
 210 is_dot_or_dash (char ch)
 211 {
 212   return ch == '.' || ch == '-';
 213 }
 214
 215 static inline bool
 216 contains_dot_or_dash (const char* p)
 217 {
 218   for (; *p; ++p)
 219     if (is_dot_or_dash (*p))
 220       return true;
 221   return false;
 222 }
 223
 224 /* Defines a variant of a symbolic name resolution. */
 225 typedef struct
 226 {
 227   /* Index in symbol list. */
 228   unsigned symbol_index;
 229
 230   /* Matched symbol id and loc. */
 231   uniqstr id;
 232   location loc;
 233
 234   /* Hiding named reference. */
 235   named_ref* hidden_by;
 236
 237   /* Error flags. May contain zero (no errors) or
 238      a combination of VARIANT_* values. */
 239   unsigned err;
 240 } variant;
 241
 242 /* Set when the variant refers to a symbol hidden
 243    by an explicit symbol reference. */
 244 #define VARIANT_HIDDEN (1 << 0)
 245
 246 /* Set when the variant refers to a symbol containing
 247    dots or dashes. Will require explicit bracketing. */
 248 #define VARIANT_BAD_BRACKETING (1 << 1)
 249
 250 /* Set when the variant refers to a symbol which is
 251    not visible from current midrule. */
 252 #define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
 253
 254 static variant *variant_table = NULL;
 255 static unsigned variant_table_size = 0;
 256 static unsigned variant_count = 0;
 257
 258 static variant *
 259 variant_table_grow (void)
 260 {
 261   ++variant_count;
 262   if (variant_count > variant_table_size)
 263     {
 264       while (variant_count > variant_table_size)
 265         variant_table_size = 2 * variant_table_size + 3;
 266       variant_table = xnrealloc (variant_table, variant_table_size,
 267                                  sizeof *variant_table);
 268     }
 269   return &variant_table[variant_count - 1];
 270 }
 271
 272 static void
 273 variant_table_free (void)
 274 {
 275   free (variant_table);
 276   variant_table = NULL;
 277   variant_table_size = variant_count = 0;
 278 }
 279
 280 static char *
 281 find_prefix_end (const char *prefix, char *begin, char *end)
 282 {
 283   char *ptr = begin;
 284
 285   for (; *prefix && ptr != end; ++prefix, ++ptr)
 286     if (*prefix != *ptr)
 287       return 0;
 288
 289   if (*prefix)
 290     return 0;
 291
 292   return ptr;
 293 }
 294
 295 static variant *
 296 variant_add (uniqstr id, location id_loc, unsigned symbol_index,
 297              char *cp, char *cp_end, bool explicit_bracketing)
 298 {
 299   char *prefix_end;
 300
 301   prefix_end = find_prefix_end (id, cp, cp_end);
 302   if (prefix_end &&
 303       (prefix_end == cp_end ||
 304        (!explicit_bracketing && is_dot_or_dash (*prefix_end))))
 305     {
 306       variant *r = variant_table_grow ();
 307       r->symbol_index = symbol_index;
 308       r->id = id;
 309       r->loc = id_loc;
 310       r->hidden_by = NULL;
 311       r->err = 0;
 312       return r;
 313     }
 314   else
 315     return NULL;
 316 }
 317
 318 static const char *
 319 get_at_spec(unsigned symbol_index)
 320 {
 321   static char at_buf[20];
 322   if (symbol_index == 0)
 323     strcpy (at_buf, "$$");
 324   else
 325     snprintf (at_buf, sizeof at_buf, "$%u", symbol_index);
 326   return at_buf;
 327 }
 328
 329 static void
 330 show_sub_message (warnings warning,
 331                   const char* cp, bool explicit_bracketing,
 332                   int midrule_rhs_index, char dollar_or_at,
 333                   unsigned indent, const variant *var)
 334 {
 335   const char *at_spec = get_at_spec (var->symbol_index);
 336
 337   if (var->err == 0)
 338     complain_indent (&var->loc, warning, &indent,
 339                      _("refers to: %c%s at %s"), dollar_or_at,
 340                      var->id, at_spec);
 341   else
 342     {
 343       static struct obstack msg_buf;
 344       const char *tail = explicit_bracketing ? "" : cp + strlen (var->id);
 345       const char *id;
 346       location id_loc;
 347
 348       if (var->hidden_by)
 349         {
 350           id = var->hidden_by->id;
 351           id_loc = var->hidden_by->loc;
 352         }
 353       else
 354         {
 355           id = var->id;
 356           id_loc = var->loc;
 357         }
 358
 359       /* Create the explanation message. */
 360       obstack_init (&msg_buf);
 361
 362       obstack_printf (&msg_buf, _("possibly meant: %c"), dollar_or_at);
 363       if (contains_dot_or_dash (id))
 364         obstack_printf (&msg_buf, "[%s]", id);
 365       else
 366         obstack_sgrow (&msg_buf, id);
 367       obstack_sgrow (&msg_buf, tail);
 368
 369       if (var->err & VARIANT_HIDDEN)
 370         {
 371           obstack_printf (&msg_buf, _(", hiding %c"), dollar_or_at);
 372           if (contains_dot_or_dash (var->id))
 373             obstack_printf (&msg_buf, "[%s]", var->id);
 374           else
 375             obstack_sgrow (&msg_buf, var->id);
 376           obstack_sgrow (&msg_buf, tail);
 377         }
 378
 379       obstack_printf (&msg_buf, _(" at %s"), at_spec);
 380
 381       if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
 382         obstack_printf (&msg_buf,
 383                         _(", cannot be accessed from mid-rule action at $%d"),
 384                         midrule_rhs_index);
 385
 386       complain_indent (&id_loc, warning, &indent, "%s",
 387                         obstack_finish0 (&msg_buf));
 388       obstack_free (&msg_buf, 0);
 389     }
 390 }
 391
 392 static void
 393 show_sub_messages (warnings warning,
 394                    const char* cp, bool explicit_bracketing,
 395                    int midrule_rhs_index, char dollar_or_at,
 396                    unsigned indent)
 397 {
 398   unsigned i;
 399
 400   for (i = 0; i < variant_count; ++i)
 401     show_sub_message (warning | silent,
 402                       cp, explicit_bracketing,
 403                       midrule_rhs_index, dollar_or_at,
 404                       indent, &variant_table[i]);
 405 }
 406
 407 /* Returned from "parse_ref" when the reference
 408    is inappropriate. */
 409 #define INVALID_REF (INT_MIN)
 410
 411 /* Returned from "parse_ref" when the reference
 412    points to LHS ($$) of the current rule or midrule. */
 413 #define LHS_REF (INT_MIN + 1)
 414
 415 /* Parse named or positional reference. In case of positional
 416    references, can return negative values for $-n "deep" stack
 417    accesses. */
 418 static long int
 419 parse_ref (char *cp, symbol_list *rule, int rule_length,
 420            int midrule_rhs_index, char *text, location text_loc,
 421            char dollar_or_at)
 422 {
 423   symbol_list *l;
 424   char *cp_end;
 425   bool explicit_bracketing;
 426   unsigned i;
 427   unsigned valid_variants = 0;
 428   unsigned valid_variant_index = 0;
 429
 430   if ('$' == *cp)
 431     return LHS_REF;
 432
 433   if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))
 434     {
 435       long int num = strtol (cp, &cp, 10);
 436       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
 437         return num;
 438       else
 439         {
 440           complain (&text_loc, complaint, _("integer out of range: %s"),
 441                     quote (text));
 442           return INVALID_REF;
 443         }
 444     }
 445
 446   if ('[' == *cp)
 447     {
 448       /* Ignore the brackets. */
 449       char *p;
 450       for (p = ++cp; *p != ']'; ++p)
 451         continue;
 452       cp_end = p;
 453
 454       explicit_bracketing = true;
 455     }
 456   else
 457     {
 458       /* Take all characters of the name. */
 459       char* p;
 460       for (p = cp; *p; ++p)
 461         if (is_dot_or_dash (*p))
 462           {
 463             ref_tail_fields = p;
 464             break;
 465           }
 466       for (p = cp; *p; ++p)
 467         continue;
 468       cp_end = p;
 469
 470       explicit_bracketing = false;
 471     }
 472
 473   /* Add all relevant variants. */
 474   {
 475     unsigned symbol_index;
 476     variant_count = 0;
 477     for (symbol_index = 0, l = rule; !symbol_list_null (l);
 478          ++symbol_index, l = l->next)
 479       {
 480         variant *var;
 481         if (l->content_type != SYMLIST_SYMBOL)
 482           continue;
 483
 484         var = variant_add (l->content.sym->tag, l->sym_loc,
 485                            symbol_index, cp, cp_end, explicit_bracketing);
 486         if (var && l->named_ref)
 487           var->hidden_by = l->named_ref;
 488
 489         if (l->named_ref)
 490           variant_add (l->named_ref->id, l->named_ref->loc,
 491                        symbol_index, cp, cp_end, explicit_bracketing);
 492       }
 493   }
 494
 495   /* Check errors. */
 496   for (i = 0; i < variant_count; ++i)
 497     {
 498       variant *var = &variant_table[i];
 499       unsigned symbol_index = var->symbol_index;
 500
 501       /* Check visibility from mid-rule actions. */
 502       if (midrule_rhs_index != 0
 503           && (symbol_index == 0 || midrule_rhs_index < symbol_index))
 504         var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
 505
 506       /* Check correct bracketing. */
 507       if (!explicit_bracketing && contains_dot_or_dash (var->id))
 508         var->err |= VARIANT_BAD_BRACKETING;
 509
 510       /* Check using of hidden symbols. */
 511       if (var->hidden_by)
 512         var->err |= VARIANT_HIDDEN;
 513
 514       if (!var->err)
 515         {
 516           valid_variant_index = i;
 517           ++valid_variants;
 518         }
 519     }
 520
 521   switch (valid_variants)
 522     {
 523     case 0:
 524       {
 525         unsigned len = (explicit_bracketing || !ref_tail_fields) ?
 526           cp_end - cp : ref_tail_fields - cp;
 527         unsigned indent = 0;
 528
 529         complain_indent (&text_loc, complaint, &indent,
 530                          _("invalid reference: %s"), quote (text));
 531         indent += SUB_INDENT;
 532         if (len == 0)
 533           {
 534             location sym_loc = text_loc;
 535             sym_loc.start.column += 1;
 536             sym_loc.end = sym_loc.start;
 537             complain_indent (&sym_loc, complaint, &indent,
 538                              _("syntax error after '%c', expecting integer, "
 539                                "letter, '_', '[', or '$'"),
 540                              dollar_or_at);
 541           }
 542         else if (midrule_rhs_index)
 543           complain_indent (&rule->location, complaint, &indent,
 544                            _("symbol not found in production before $%d: "
 545                              "%.*s"),
 546                            midrule_rhs_index, len, cp);
 547         else
 548           complain_indent (&rule->location, complaint, &indent,
 549                            _("symbol not found in production: %.*s"),
 550                            len, cp);
 551
 552         if (variant_count > 0)
 553           show_sub_messages (complaint,
 554                              cp, explicit_bracketing, midrule_rhs_index,
 555                              dollar_or_at, indent);
 556         return INVALID_REF;
 557       }
 558     case 1:
 559       {
 560         unsigned indent = 0;
 561         if (variant_count > 1)
 562           {
 563             complain_indent (&text_loc, Wother, &indent,
 564                              _("misleading reference: %s"), quote (text));
 565             show_sub_messages (Wother,
 566                                cp, explicit_bracketing, midrule_rhs_index,
 567                                dollar_or_at, indent + SUB_INDENT);
 568           }
 569         {
 570           unsigned symbol_index =
 571             variant_table[valid_variant_index].symbol_index;
 572           return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
 573         }
 574       }
 575     case 2:
 576     default:
 577       {
 578         unsigned indent = 0;
 579         complain_indent (&text_loc, complaint, &indent,
 580                          _("ambiguous reference: %s"), quote (text));
 581         show_sub_messages (complaint,
 582                            cp, explicit_bracketing, midrule_rhs_index,
 583                            dollar_or_at, indent + SUB_INDENT);
 584         return INVALID_REF;
 585       }
 586     }
 587 }
 588
 589 /* Keeps track of the maximum number of semantic values to the left of
 590    a handle (those referenced by $0, $-1, etc.) are required by the
 591    semantic actions of this grammar. */
 592 int max_left_semantic_context = 0;
 593
 594
 595 /* If CP points to a typename (i.e., <.*?>), set TYPE_NAME to its
 596    beginning (i.e., after the opening "<", and return the pointer
 597    immediately after it.  */
 598
 599 static
 600 char *
 601 fetch_type_name (char *cp, char const **type_name,
 602                  location dollar_loc)
 603 {
 604   if (*cp == '<')
 605     {
 606       *type_name = ++cp;
 607       /* Series of non-'>' or "->".  */
 608       while (*cp != '>' || cp[-1] == '-')
 609         ++cp;
 610
 611       /* The '>' symbol will be later replaced by '\0'. Original
 612          'text' is needed for error messages. */
 613       ++cp;
 614       if (untyped_var_seen)
 615         complain (&dollar_loc, complaint,
 616                   _("explicit type given in untyped grammar"));
 617       tag_seen = true;
 618     }
 619   return cp;
 620 }
 621
 622 /*------------------------------------------------------------------.
 623 | TEXT is pointing to a wannabee semantic value (i.e., a '$').      |
 624 |                                                                   |
 625 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 626 |                                                                   |
 627 | Output to OBSTACK_FOR_STRING a reference to this semantic value.  |
 628 `------------------------------------------------------------------*/
 629
 630 static void
 631 handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 632 {
 633   char const *type_name = NULL;
 634   char *cp = text + 1;
 635   symbol_list *effective_rule;
 636   int effective_rule_length;
 637   int n;
 638
 639   if (rule->midrule_parent_rule)
 640     {
 641       effective_rule = rule->midrule_parent_rule;
 642       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 643     }
 644   else
 645     {
 646       effective_rule = rule;
 647       effective_rule_length = symbol_list_length (rule->next);
 648     }
 649
 650   /* Get the type name if explicit. */
 651   cp = fetch_type_name (cp, &type_name, dollar_loc);
 652
 653   n = parse_ref (cp, effective_rule, effective_rule_length,
 654                  rule->midrule_parent_rhs_index, text, dollar_loc, '$');
 655
 656   /* End type_name. */
 657   if (type_name)
 658     cp[-1] = '\0';
 659
 660   switch (n)
 661     {
 662     case INVALID_REF:
 663       break;
 664
 665     case LHS_REF:
 666       if (!type_name)
 667         type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
 668
 669       if (!type_name)
 670         {
 671           if (union_seen | tag_seen)
 672             {
 673               if (rule->midrule_parent_rule)
 674                 complain (&dollar_loc, complaint,
 675                              _("$$ for the midrule at $%d of %s"
 676                                " has no declared type"),
 677                              rule->midrule_parent_rhs_index,
 678                              quote (effective_rule->content.sym->tag));
 679               else
 680                 complain (&dollar_loc, complaint,
 681                           _("$$ of %s has no declared type"),
 682                           quote (rule->content.sym->tag));
 683             }
 684           else
 685             untyped_var_seen = true;
 686         }
 687
 688       obstack_sgrow (&obstack_for_string, "]b4_lhs_value(");
 689       obstack_quote (&obstack_for_string, type_name);
 690       obstack_sgrow (&obstack_for_string, ")[");
 691       rule->action_props.is_value_used = true;
 692       break;
 693
 694     default:
 695       if (max_left_semantic_context < 1 - n)
 696         max_left_semantic_context = 1 - n;
 697       if (!type_name && 0 < n)
 698         type_name =
 699           symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
 700       if (!type_name)
 701         {
 702           if (union_seen | tag_seen)
 703             complain (&dollar_loc, complaint,
 704                       _("$%s of %s has no declared type"), cp,
 705                       quote (effective_rule->content.sym->tag));
 706           else
 707             untyped_var_seen = true;
 708         }
 709
 710       obstack_printf (&obstack_for_string,
 711                       "]b4_rhs_value(%d, %d, ", effective_rule_length, n);
 712       obstack_quote (&obstack_for_string, type_name);
 713       obstack_sgrow (&obstack_for_string, ")[");
 714       if (n > 0)
 715         symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
 716           true;
 717       break;
 718     }
 719 }
 720
 721
 722 /*------------------------------------------------------.
 723 | TEXT is a location token (i.e., a '@...').  Output to |
 724 | OBSTACK_FOR_STRING a reference to this location.      |
 725 `------------------------------------------------------*/
 726
 727 static void
 728 handle_action_at (symbol_list *rule, char *text, location at_loc)
 729 {
 730   char *cp = text + 1;
 731   symbol_list *effective_rule;
 732   int effective_rule_length;
 733   int n;
 734
 735   if (rule->midrule_parent_rule)
 736     {
 737       effective_rule = rule->midrule_parent_rule;
 738       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 739     }
 740   else
 741     {
 742       effective_rule = rule;
 743       effective_rule_length = symbol_list_length (rule->next);
 744     }
 745
 746   muscle_percent_define_ensure("locations", at_loc, true);
 747
 748   n = parse_ref (cp, effective_rule, effective_rule_length,
 749                        rule->midrule_parent_rhs_index, text, at_loc, '@');
 750   switch (n)
 751     {
 752     case INVALID_REF:
 753       break;
 754
 755     case LHS_REF:
 756       obstack_sgrow (&obstack_for_string, "]b4_lhs_location[");
 757       break;
 758
 759     default:
 760       obstack_printf (&obstack_for_string, "]b4_rhs_location(%d, %d)[",
 761                       effective_rule_length, n);
 762       break;
 763     }
 764 }
 765
 766
 767 /*-------------------------.
 768 | Initialize the scanner.  |
 769 `-------------------------*/
 770
 771 /* Translate the dollars and ats in \a self, in the context \a sc_context
 772    (SC_RULE_ACTION, SC_SYMBOL_ACTION, INITIAL).  */
 773
 774 static char const *
 775 translate_action (code_props *self, int sc_context)
 776 {
 777   char *res;
 778   static bool initialized = false;
 779   if (!initialized)
 780     {
 781       obstack_init (&obstack_for_string);
 782       yy_flex_debug = 0;
 783       initialized = true;
 784     }
 785
 786   loc->start = loc->end = self->location.start;
 787   yy_switch_to_buffer (yy_scan_string (self->code));
 788   res = code_lex (self, sc_context);
 789   yy_delete_buffer (YY_CURRENT_BUFFER);
 790
 791   return res;
 792 }
 793
 794 /*------------------------------------------------------------------------.
 795 | Implementation of the public interface as documented in "scan-code.h".  |
 796 `------------------------------------------------------------------------*/
 797
 798 void
 799 code_props_none_init (code_props *self)
 800 {
 801   *self = code_props_none;
 802 }
 803
 804 code_props code_props_none = CODE_PROPS_NONE_INIT;
 805
 806 void
 807 code_props_plain_init (code_props *self, char const *code,
 808                        location code_loc)
 809 {
 810   code_props_none_init (self);
 811   self->kind = CODE_PROPS_PLAIN;
 812   self->code = code;
 813   self->location = code_loc;
 814 }
 815
 816 void
 817 code_props_symbol_action_init (code_props *self, char const *code,
 818                                location code_loc)
 819 {
 820   code_props_none_init (self);
 821   self->kind = CODE_PROPS_SYMBOL_ACTION;
 822   self->code = code;
 823   self->location = code_loc;
 824 }
 825
 826 void
 827 code_props_rule_action_init (code_props *self, char const *code,
 828                              location code_loc, symbol_list *rule,
 829                              named_ref *name, bool is_predicate)
 830 {
 831   code_props_none_init (self);
 832   self->kind = CODE_PROPS_RULE_ACTION;
 833   self->code = code;
 834   self->location = code_loc;
 835   self->rule = rule;
 836   self->named_ref = name;
 837   self->is_predicate = is_predicate;
 838 }
 839
 840 void
 841 code_props_translate_code (code_props *self)
 842 {
 843   switch (self->kind)
 844     {
 845       case CODE_PROPS_NONE:
 846         break;
 847       case CODE_PROPS_PLAIN:
 848         self->code = translate_action (self, INITIAL);
 849         break;
 850       case CODE_PROPS_SYMBOL_ACTION:
 851         self->code = translate_action (self, SC_SYMBOL_ACTION);
 852         break;
 853       case CODE_PROPS_RULE_ACTION:
 854         self->code = translate_action (self, SC_RULE_ACTION);
 855         break;
 856     }
 857 }
 858
 859 void
 860 code_scanner_last_string_free (void)
 861 {
 862   STRING_FREE;
 863 }
 864
 865 void
 866 code_scanner_free (void)
 867 {
 868   obstack_free (&obstack_for_string, 0);
 869   variant_table_free ();
 870
 871   /* Reclaim Flex's buffers.  */
 872   yylex_destroy ();
 873 }