src/scan-code.l

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