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 = var->hidden_by ? var->hidden_by->id : var->id;
 346       location id_loc = var->hidden_by ? var->hidden_by->loc : var->loc;
 347
 348       /* Create the explanation message. */
 349       obstack_init (&msg_buf);
 350
 351       obstack_printf (&msg_buf, _("possibly meant: %c"), dollar_or_at);
 352       if (contains_dot_or_dash (id))
 353         obstack_printf (&msg_buf, "[%s]", id);
 354       else
 355         obstack_sgrow (&msg_buf, id);
 356       obstack_sgrow (&msg_buf, tail);
 357
 358       if (var->err & VARIANT_HIDDEN)
 359         {
 360           obstack_printf (&msg_buf, _(", hiding %c"), dollar_or_at);
 361           if (contains_dot_or_dash (var->id))
 362             obstack_printf (&msg_buf, "[%s]", var->id);
 363           else
 364             obstack_sgrow (&msg_buf, var->id);
 365           obstack_sgrow (&msg_buf, tail);
 366         }
 367
 368       obstack_printf (&msg_buf, _(" at %s"), at_spec);
 369
 370       if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
 371         obstack_printf (&msg_buf,
 372                         _(", cannot be accessed from mid-rule action at $%d"),
 373                         midrule_rhs_index);
 374
 375       complain_indent (&id_loc, warning, &indent, "%s",
 376                         obstack_finish0 (&msg_buf));
 377       obstack_free (&msg_buf, 0);
 378     }
 379 }
 380
 381 static void
 382 show_sub_messages (warnings warning,
 383                    const char* cp, bool explicit_bracketing,
 384                    int midrule_rhs_index, char dollar_or_at,
 385                    unsigned indent)
 386 {
 387   unsigned i;
 388
 389   for (i = 0; i < variant_count; ++i)
 390     show_sub_message (warning | silent,
 391                       cp, explicit_bracketing,
 392                       midrule_rhs_index, dollar_or_at,
 393                       indent, &variant_table[i]);
 394 }
 395
 396 /* Returned from "parse_ref" when the reference
 397    is inappropriate. */
 398 #define INVALID_REF (INT_MIN)
 399
 400 /* Returned from "parse_ref" when the reference
 401    points to LHS ($$) of the current rule or midrule. */
 402 #define LHS_REF (INT_MIN + 1)
 403
 404 /* Parse named or positional reference. In case of positional
 405    references, can return negative values for $-n "deep" stack
 406    accesses. */
 407 static long int
 408 parse_ref (char *cp, symbol_list *rule, int rule_length,
 409            int midrule_rhs_index, char *text, location text_loc,
 410            char dollar_or_at)
 411 {
 412   symbol_list *l;
 413   char *cp_end;
 414   bool explicit_bracketing;
 415   unsigned i;
 416   unsigned valid_variants = 0;
 417   unsigned valid_variant_index = 0;
 418
 419   if ('$' == *cp)
 420     return LHS_REF;
 421
 422   if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))
 423     {
 424       long int num = strtol (cp, &cp, 10);
 425       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
 426         return num;
 427       else
 428         {
 429           complain (&text_loc, complaint, _("integer out of range: %s"),
 430                     quote (text));
 431           return INVALID_REF;
 432         }
 433     }
 434
 435   if ('[' == *cp)
 436     {
 437       /* Ignore the brackets. */
 438       char *p;
 439       for (p = ++cp; *p != ']'; ++p)
 440         continue;
 441       cp_end = p;
 442
 443       explicit_bracketing = true;
 444     }
 445   else
 446     {
 447       /* Take all characters of the name. */
 448       char* p;
 449       for (p = cp; *p; ++p)
 450         if (is_dot_or_dash (*p))
 451           {
 452             ref_tail_fields = p;
 453             break;
 454           }
 455       for (p = cp; *p; ++p)
 456         continue;
 457       cp_end = p;
 458
 459       explicit_bracketing = false;
 460     }
 461
 462   /* Add all relevant variants. */
 463   {
 464     unsigned symbol_index;
 465     variant_count = 0;
 466     for (symbol_index = 0, l = rule; !symbol_list_null (l);
 467          ++symbol_index, l = l->next)
 468       {
 469         variant *var;
 470         if (l->content_type != SYMLIST_SYMBOL)
 471           continue;
 472
 473         var = variant_add (l->content.sym->tag, l->sym_loc,
 474                            symbol_index, cp, cp_end, explicit_bracketing);
 475         if (var && l->named_ref)
 476           var->hidden_by = l->named_ref;
 477
 478         if (l->named_ref)
 479           variant_add (l->named_ref->id, l->named_ref->loc,
 480                        symbol_index, cp, cp_end, explicit_bracketing);
 481       }
 482   }
 483
 484   /* Check errors. */
 485   for (i = 0; i < variant_count; ++i)
 486     {
 487       variant *var = &variant_table[i];
 488       unsigned symbol_index = var->symbol_index;
 489
 490       /* Check visibility from mid-rule actions. */
 491       if (midrule_rhs_index != 0
 492           && (symbol_index == 0 || midrule_rhs_index < symbol_index))
 493         var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
 494
 495       /* Check correct bracketing. */
 496       if (!explicit_bracketing && contains_dot_or_dash (var->id))
 497         var->err |= VARIANT_BAD_BRACKETING;
 498
 499       /* Check using of hidden symbols. */
 500       if (var->hidden_by)
 501         var->err |= VARIANT_HIDDEN;
 502
 503       if (!var->err)
 504         {
 505           valid_variant_index = i;
 506           ++valid_variants;
 507         }
 508     }
 509
 510   switch (valid_variants)
 511     {
 512     case 0:
 513       {
 514         unsigned len = (explicit_bracketing || !ref_tail_fields) ?
 515           cp_end - cp : ref_tail_fields - cp;
 516         unsigned indent = 0;
 517
 518         complain_indent (&text_loc, complaint, &indent,
 519                          _("invalid reference: %s"), quote (text));
 520         indent += SUB_INDENT;
 521         if (len == 0)
 522           {
 523             location sym_loc = text_loc;
 524             sym_loc.start.column += 1;
 525             sym_loc.end = sym_loc.start;
 526             complain_indent (&sym_loc, complaint, &indent,
 527                              _("syntax error after '%c', expecting integer, "
 528                                "letter, '_', '[', or '$'"),
 529                              dollar_or_at);
 530           }
 531         else if (midrule_rhs_index)
 532           complain_indent (&rule->location, complaint, &indent,
 533                            _("symbol not found in production before $%d: "
 534                              "%.*s"),
 535                            midrule_rhs_index, len, cp);
 536         else
 537           complain_indent (&rule->location, complaint, &indent,
 538                            _("symbol not found in production: %.*s"),
 539                            len, cp);
 540
 541         if (variant_count > 0)
 542           show_sub_messages (complaint,
 543                              cp, explicit_bracketing, midrule_rhs_index,
 544                              dollar_or_at, indent);
 545         return INVALID_REF;
 546       }
 547     case 1:
 548       {
 549         unsigned indent = 0;
 550         if (variant_count > 1)
 551           {
 552             complain_indent (&text_loc, Wother, &indent,
 553                              _("misleading reference: %s"), quote (text));
 554             show_sub_messages (Wother,
 555                                cp, explicit_bracketing, midrule_rhs_index,
 556                                dollar_or_at, indent + SUB_INDENT);
 557           }
 558         {
 559           unsigned symbol_index =
 560             variant_table[valid_variant_index].symbol_index;
 561           return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
 562         }
 563       }
 564     case 2:
 565     default:
 566       {
 567         unsigned indent = 0;
 568         complain_indent (&text_loc, complaint, &indent,
 569                          _("ambiguous reference: %s"), quote (text));
 570         show_sub_messages (complaint,
 571                            cp, explicit_bracketing, midrule_rhs_index,
 572                            dollar_or_at, indent + SUB_INDENT);
 573         return INVALID_REF;
 574       }
 575     }
 576
 577   /* Not reachable. */
 578   return INVALID_REF;
 579 }
 580
 581 /* Keeps track of the maximum number of semantic values to the left of
 582    a handle (those referenced by $0, $-1, etc.) are required by the
 583    semantic actions of this grammar. */
 584 int max_left_semantic_context = 0;
 585
 586
 587 /* If CP points to a typename (i.e., <.*?>), set TYPE_NAME to its
 588    beginning (i.e., after the opening "<", and return the pointer
 589    immediately after it.  */
 590
 591 static
 592 char *
 593 fetch_type_name (char *cp, char const **type_name,
 594                  location dollar_loc)
 595 {
 596   if (*cp == '<')
 597     {
 598       *type_name = ++cp;
 599       /* Series of non-'>' or "->".  */
 600       while (*cp != '>' || cp[-1] == '-')
 601         ++cp;
 602
 603       /* The '>' symbol will be later replaced by '\0'. Original
 604          'text' is needed for error messages. */
 605       ++cp;
 606       if (untyped_var_seen)
 607         complain (&dollar_loc, complaint,
 608                   _("explicit type given in untyped grammar"));
 609       tag_seen = true;
 610     }
 611   return cp;
 612 }
 613
 614 /*------------------------------------------------------------------.
 615 | TEXT is pointing to a wannabee semantic value (i.e., a '$').      |
 616 |                                                                   |
 617 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 618 |                                                                   |
 619 | Output to OBSTACK_FOR_STRING a reference to this semantic value.  |
 620 `------------------------------------------------------------------*/
 621
 622 static void
 623 handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 624 {
 625   char const *type_name = NULL;
 626   char *cp = text + 1;
 627   symbol_list *effective_rule;
 628   int effective_rule_length;
 629   int n;
 630
 631   if (rule->midrule_parent_rule)
 632     {
 633       effective_rule = rule->midrule_parent_rule;
 634       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 635     }
 636   else
 637     {
 638       effective_rule = rule;
 639       effective_rule_length = symbol_list_length (rule->next);
 640     }
 641
 642   /* Get the type name if explicit. */
 643   cp = fetch_type_name (cp, &type_name, dollar_loc);
 644
 645   n = parse_ref (cp, effective_rule, effective_rule_length,
 646                  rule->midrule_parent_rhs_index, text, dollar_loc, '$');
 647
 648   /* End type_name. */
 649   if (type_name)
 650     cp[-1] = '\0';
 651
 652   switch (n)
 653     {
 654     case INVALID_REF:
 655       break;
 656
 657     case LHS_REF:
 658       if (!type_name)
 659         type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
 660
 661       if (!type_name)
 662         {
 663           if (union_seen | tag_seen)
 664             {
 665               if (rule->midrule_parent_rule)
 666                 complain (&dollar_loc, complaint,
 667                              _("$$ for the midrule at $%d of %s"
 668                                " has no declared type"),
 669                              rule->midrule_parent_rhs_index,
 670                              quote (effective_rule->content.sym->tag));
 671               else
 672                 complain (&dollar_loc, complaint,
 673                           _("$$ of %s has no declared type"),
 674                           quote (rule->content.sym->tag));
 675             }
 676           else
 677             untyped_var_seen = true;
 678         }
 679
 680       obstack_sgrow (&obstack_for_string, "]b4_lhs_value(");
 681       obstack_quote (&obstack_for_string, type_name);
 682       obstack_sgrow (&obstack_for_string, ")[");
 683       rule->action_props.is_value_used = true;
 684       break;
 685
 686     default:
 687       if (max_left_semantic_context < 1 - n)
 688         max_left_semantic_context = 1 - n;
 689       if (!type_name && 0 < n)
 690         type_name =
 691           symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
 692       if (!type_name)
 693         {
 694           if (union_seen | tag_seen)
 695             complain (&dollar_loc, complaint,
 696                       _("$%s of %s has no declared type"), cp,
 697                       quote (effective_rule->content.sym->tag));
 698           else
 699             untyped_var_seen = true;
 700         }
 701
 702       obstack_printf (&obstack_for_string,
 703                       "]b4_rhs_value(%d, %d, ", effective_rule_length, n);
 704       obstack_quote (&obstack_for_string, type_name);
 705       obstack_sgrow (&obstack_for_string, ")[");
 706       if (n > 0)
 707         symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
 708           true;
 709       break;
 710     }
 711 }
 712
 713
 714 /*------------------------------------------------------.
 715 | TEXT is a location token (i.e., a '@...').  Output to |
 716 | OBSTACK_FOR_STRING a reference to this location.      |
 717 `------------------------------------------------------*/
 718
 719 static void
 720 handle_action_at (symbol_list *rule, char *text, location at_loc)
 721 {
 722   char *cp = text + 1;
 723   symbol_list *effective_rule;
 724   int effective_rule_length;
 725   int 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   muscle_percent_define_ensure("locations", at_loc, true);
 739
 740   n = parse_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_printf (&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 code_props_none = CODE_PROPS_NONE_INIT;
 797
 798 void
 799 code_props_plain_init (code_props *self, char const *code,
 800                        location code_loc)
 801 {
 802   code_props_none_init (self);
 803   self->kind = CODE_PROPS_PLAIN;
 804   self->code = code;
 805   self->location = code_loc;
 806 }
 807
 808 void
 809 code_props_symbol_action_init (code_props *self, char const *code,
 810                                location code_loc)
 811 {
 812   code_props_none_init (self);
 813   self->kind = CODE_PROPS_SYMBOL_ACTION;
 814   self->code = code;
 815   self->location = code_loc;
 816 }
 817
 818 void
 819 code_props_rule_action_init (code_props *self, char const *code,
 820                              location code_loc, symbol_list *rule,
 821                              named_ref *name, bool is_predicate)
 822 {
 823   code_props_none_init (self);
 824   self->kind = CODE_PROPS_RULE_ACTION;
 825   self->code = code;
 826   self->location = code_loc;
 827   self->rule = rule;
 828   self->named_ref = name;
 829   self->is_predicate = is_predicate;
 830 }
 831
 832 void
 833 code_props_translate_code (code_props *self)
 834 {
 835   switch (self->kind)
 836     {
 837       case CODE_PROPS_NONE:
 838         break;
 839       case CODE_PROPS_PLAIN:
 840         self->code = translate_action (self, INITIAL);
 841         break;
 842       case CODE_PROPS_SYMBOL_ACTION:
 843         self->code = translate_action (self, SC_SYMBOL_ACTION);
 844         break;
 845       case CODE_PROPS_RULE_ACTION:
 846         self->code = translate_action (self, SC_RULE_ACTION);
 847         break;
 848     }
 849 }
 850
 851 void
 852 code_scanner_last_string_free (void)
 853 {
 854   STRING_FREE;
 855 }
 856
 857 void
 858 code_scanner_free (void)
 859 {
 860   obstack_free (&obstack_for_string, 0);
 861   variant_table_free ();
 862
 863   /* Reclaim Flex's buffers.  */
 864   yylex_destroy ();
 865 }