src/scan-code.l

   1 /* Bison Action Scanner                             -*- C -*-
   2
   3    Copyright (C) 2006-2012 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.  */
  82 tag      [^\0\n>]+
  83
  84 /* Zero or more instances of backslash-newline.  Following GCC, allow
  85    white space between the backslash and the newline.  */
  86 splice   (\\[ \f\t\v]*\n)*
  87
  88 /* C style identifier. Must start with letter. Will be used for
  89    named symbol references. Shall be kept synchronized with
  90    scan-gram.l "letter" and "id". */
  91 letter    [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
  92 id        {letter}({letter}|[-0-9])*
  93 ref      -?[0-9]+|{id}|"["{id}"]"|"$"
  94
  95 %%
  96
  97 %{
  98   /* Nesting level of the current code in braces.  */
  99   int braces_level = 0;
 100
 101   /* Whether a semicolon is probably needed.
 102
 103      The heuristic is that a semicolon is not needed after '{', '}',
 104      ';', or a C preprocessor directive, and that whitespaces and
 105      comments do not affect this flag.  Note that '{' does not need a
 106      semicolon because of '{}'.  A semicolon may be needed before a
 107      cpp directive, but don't bother.
 108
 109      While it is maintained in several start-conditions (factoring
 110      opportunities), it is meaningful only for SC_RULE_ACTION. */
 111   bool need_semicolon = false;
 112
 113   /* Whether in a C preprocessor directive.  Don't use a start condition
 114      for this because, at the end of strings and comments, we still need
 115      to know whether we're in a directive.  */
 116   bool in_cpp = false;
 117
 118   /* This scanner is special: it is invoked only once, henceforth
 119      is expected to return only once.  This initialization is
 120      therefore done once per action to translate. */
 121   aver (sc_context == SC_SYMBOL_ACTION
 122         || sc_context == SC_RULE_ACTION
 123         || sc_context == INITIAL);
 124   BEGIN sc_context;
 125 %}
 126
 127   /*------------------------------------------------------------.
 128   | Scanning a C comment.  The initial '/ *' is already eaten.  |
 129   `------------------------------------------------------------*/
 130
 131 <SC_COMMENT>
 132 {
 133   "*"{splice}"/"  STRING_GROW; BEGIN sc_context;
 134 }
 135
 136
 137   /*--------------------------------------------------------------.
 138   | Scanning a line comment.  The initial '//' is already eaten.  |
 139   `--------------------------------------------------------------*/
 140
 141 <SC_LINE_COMMENT>
 142 {
 143   "\n"           STRING_GROW; BEGIN sc_context;
 144   {splice}       STRING_GROW;
 145 }
 146
 147
 148   /*--------------------------------------------.
 149   | Scanning user-code characters and strings.  |
 150   `--------------------------------------------*/
 151
 152 <SC_CHARACTER,SC_STRING>
 153 {
 154   {splice}|\\{splice}.  STRING_GROW;
 155 }
 156
 157 <SC_CHARACTER>
 158 {
 159   "'"           STRING_GROW; BEGIN sc_context;
 160 }
 161
 162 <SC_STRING>
 163 {
 164   "\""          STRING_GROW; BEGIN sc_context;
 165 }
 166
 167
 168 <SC_RULE_ACTION,SC_SYMBOL_ACTION>
 169 {
 170   "'" {
 171     STRING_GROW;
 172     BEGIN SC_CHARACTER;
 173     need_semicolon = true;
 174   }
 175   "\"" {
 176     STRING_GROW;
 177     BEGIN SC_STRING;
 178     need_semicolon = true;
 179   }
 180   "/"{splice}"*" {
 181     STRING_GROW;
 182     BEGIN SC_COMMENT;
 183   }
 184   "/"{splice}"/" {
 185     STRING_GROW;
 186     BEGIN SC_LINE_COMMENT;
 187   }
 188   [$@]  {
 189     complain_at (*loc, Wother, _("stray '%s'"), yytext);
 190     obstack_escape (&obstack_for_string, yytext);
 191     need_semicolon = true;
 192   }
 193   [\[\]]  {
 194     obstack_escape (&obstack_for_string, yytext);
 195     need_semicolon = true;
 196   }
 197 }
 198
 199 <SC_RULE_ACTION>
 200 {
 201   "$"("<"{tag}">")?{ref}  {
 202     ref_tail_fields = NULL;
 203     handle_action_dollar (self->rule, yytext, *loc);
 204     if (ref_tail_fields)
 205       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 206     need_semicolon = true;
 207   }
 208   "@"{ref} {
 209     ref_tail_fields = NULL;
 210     handle_action_at (self->rule, yytext, *loc);
 211     if (ref_tail_fields)
 212       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 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         complain_at (*loc, Wdeprecated,
 229                      _("a ';' might be needed at the end of action code"));
 230         complain_at (*loc, Wdeprecated,
 231                      _("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   "$"("<"{tag}">")?"$" {
 254     const char *type_name = NULL;
 255     fetch_type_name (yytext + 1, &type_name, *loc)[-1] = 0;
 256     obstack_sgrow (&obstack_for_string, "]b4_dollar_dollar(");
 257     obstack_quote (&obstack_for_string, type_name);
 258     obstack_sgrow (&obstack_for_string, ")[");
 259     self->is_value_used = true;
 260   }
 261   "@$" {
 262     obstack_sgrow (&obstack_for_string, "]b4_at_dollar[");
 263     muscle_percent_define_ensure("locations", the_location, true);
 264   }
 265 }
 266
 267
 268 <*>
 269 {
 270   /* Escape M4 quoting characters in C code.  */
 271   [$@\[\]]    obstack_escape (&obstack_for_string, yytext);
 272
 273   /* By default, grow the string obstack with the input.  */
 274   .|\n        STRING_GROW;
 275
 276  /* End of processing. */
 277   <<EOF>>     STRING_FINISH; return last_string;
 278 }
 279
 280 %%
 281
 282 static inline bool
 283 is_dot_or_dash (char ch)
 284 {
 285   return ch == '.' || ch == '-';
 286 }
 287
 288 static inline bool
 289 contains_dot_or_dash (const char* p)
 290 {
 291   for (; *p; ++p)
 292     if (is_dot_or_dash (*p))
 293       return true;
 294   return false;
 295 }
 296
 297 /* Defines a variant of a symbolic name resolution. */
 298 typedef struct
 299 {
 300   /* Index in symbol list. */
 301   unsigned symbol_index;
 302
 303   /* Matched symbol id and loc. */
 304   uniqstr id;
 305   location loc;
 306
 307   /* Hiding named reference. */
 308   named_ref* hidden_by;
 309
 310   /* Error flags. May contain zero (no errors) or
 311      a combination of VARIANT_* values. */
 312   unsigned err;
 313 } variant;
 314
 315 /* Set when the variant refers to a symbol hidden
 316    by an explicit symbol reference. */
 317 #define VARIANT_HIDDEN (1 << 0)
 318
 319 /* Set when the variant refers to a symbol containing
 320    dots or dashes. Will require explicit bracketing. */
 321 #define VARIANT_BAD_BRACKETING (1 << 1)
 322
 323 /* Set when the variant refers to a symbol which is
 324    not visible from current midrule. */
 325 #define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
 326
 327 static variant *variant_table = NULL;
 328 static unsigned variant_table_size = 0;
 329 static unsigned variant_count = 0;
 330
 331 static variant *
 332 variant_table_grow (void)
 333 {
 334   ++variant_count;
 335   if (variant_count > variant_table_size)
 336     {
 337       while (variant_count > variant_table_size)
 338         variant_table_size = 2 * variant_table_size + 3;
 339       variant_table = xnrealloc (variant_table, variant_table_size,
 340                                  sizeof *variant_table);
 341     }
 342   return &variant_table[variant_count - 1];
 343 }
 344
 345 static void
 346 variant_table_free (void)
 347 {
 348   free (variant_table);
 349   variant_table = NULL;
 350   variant_table_size = variant_count = 0;
 351 }
 352
 353 static char *
 354 find_prefix_end (const char *prefix, char *begin, char *end)
 355 {
 356   char *ptr = begin;
 357
 358   for (; *prefix && ptr != end; ++prefix, ++ptr)
 359     if (*prefix != *ptr)
 360       return 0;
 361
 362   if (*prefix)
 363     return 0;
 364
 365   return ptr;
 366 }
 367
 368 static variant *
 369 variant_add (uniqstr id, location id_loc, unsigned symbol_index,
 370              char *cp, char *cp_end, bool explicit_bracketing)
 371 {
 372   char *prefix_end;
 373
 374   prefix_end = find_prefix_end (id, cp, cp_end);
 375   if (prefix_end &&
 376       (prefix_end == cp_end ||
 377        (!explicit_bracketing && is_dot_or_dash (*prefix_end))))
 378     {
 379       variant *r = variant_table_grow ();
 380       r->symbol_index = symbol_index;
 381       r->id = id;
 382       r->loc = id_loc;
 383       r->hidden_by = NULL;
 384       r->err = 0;
 385       return r;
 386     }
 387   else
 388     return NULL;
 389 }
 390
 391 static const char *
 392 get_at_spec(unsigned symbol_index)
 393 {
 394   static char at_buf[20];
 395   if (symbol_index == 0)
 396     strcpy (at_buf, "$$");
 397   else
 398     snprintf (at_buf, sizeof at_buf, "$%u", symbol_index);
 399   return at_buf;
 400 }
 401
 402 static void
 403 show_sub_message (const char* cp, bool explicit_bracketing,
 404                   int midrule_rhs_index, char dollar_or_at,
 405                   warnings wflags, unsigned indent,
 406                   const variant *var)
 407 {
 408   const char *at_spec = get_at_spec (var->symbol_index);
 409
 410   if (var->err == 0)
 411     complain_at_indent (var->loc, wflags, &indent,
 412                         _("refers to: %c%s at %s"), dollar_or_at,
 413                         var->id, at_spec);
 414   else
 415     {
 416       static struct obstack msg_buf;
 417       const char *tail = explicit_bracketing ? "" : cp + strlen (var->id);
 418       const char *id = var->hidden_by ? var->hidden_by->id : var->id;
 419       location id_loc = var->hidden_by ? var->hidden_by->loc : var->loc;
 420
 421       /* Create the explanation message. */
 422       obstack_init (&msg_buf);
 423
 424       obstack_printf (&msg_buf, _("possibly meant: %c"), dollar_or_at);
 425       if (contains_dot_or_dash (id))
 426         obstack_printf (&msg_buf, "[%s]", id);
 427       else
 428         obstack_sgrow (&msg_buf, id);
 429       obstack_sgrow (&msg_buf, tail);
 430
 431       if (var->err & VARIANT_HIDDEN)
 432         {
 433           obstack_printf (&msg_buf, _(", hiding %c"), dollar_or_at);
 434           if (contains_dot_or_dash (var->id))
 435             obstack_printf (&msg_buf, "[%s]", var->id);
 436           else
 437             obstack_sgrow (&msg_buf, var->id);
 438           obstack_sgrow (&msg_buf, tail);
 439         }
 440
 441       obstack_printf (&msg_buf, _(" at %s"), at_spec);
 442
 443       if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
 444         obstack_printf (&msg_buf,
 445                         _(", cannot be accessed from mid-rule action at $%d"),
 446                         midrule_rhs_index);
 447
 448       complain_at_indent (id_loc, wflags, &indent, "%s",
 449                           obstack_finish0 (&msg_buf));
 450       obstack_free (&msg_buf, 0);
 451     }
 452 }
 453
 454 static void
 455 show_sub_messages (const char* cp, bool explicit_bracketing,
 456                    int midrule_rhs_index, char dollar_or_at,
 457                    warnings wflags, unsigned indent)
 458 {
 459   unsigned i;
 460
 461   for (i = 0; i < variant_count; ++i)
 462     show_sub_message (cp, explicit_bracketing,
 463                       midrule_rhs_index, dollar_or_at,
 464                       wflags, indent, &variant_table[i]);
 465 }
 466
 467 /* Returned from "parse_ref" when the reference
 468    is inappropriate. */
 469 #define INVALID_REF (INT_MIN)
 470
 471 /* Returned from "parse_ref" when the reference
 472    points to LHS ($$) of the current rule or midrule. */
 473 #define LHS_REF (INT_MIN + 1)
 474
 475 /* Sub-messages indent. */
 476 #define SUB_INDENT (4)
 477
 478 /* Parse named or positional reference. In case of positional
 479    references, can return negative values for $-n "deep" stack
 480    accesses. */
 481 static long int
 482 parse_ref (char *cp, symbol_list *rule, int rule_length,
 483            int midrule_rhs_index, char *text, location text_loc,
 484            char dollar_or_at)
 485 {
 486   symbol_list *l;
 487   char *cp_end;
 488   bool explicit_bracketing;
 489   unsigned i;
 490   unsigned valid_variants = 0;
 491   unsigned valid_variant_index = 0;
 492
 493   if ('$' == *cp)
 494     return LHS_REF;
 495
 496   if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))
 497     {
 498       long int num = strtol (cp, &cp, 10);
 499       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
 500         return num;
 501       else
 502         {
 503           complain_at (text_loc, complaint, _("integer out of range: %s"),
 504                        quote (text));
 505           return INVALID_REF;
 506         }
 507     }
 508
 509   if ('[' == *cp)
 510     {
 511       /* Ignore the brackets. */
 512       char *p;
 513       for (p = ++cp; *p != ']'; ++p)
 514         continue;
 515       cp_end = p;
 516
 517       explicit_bracketing = true;
 518     }
 519   else
 520     {
 521       /* Take all characters of the name. */
 522       char* p;
 523       for (p = cp; *p; ++p)
 524         if (is_dot_or_dash (*p))
 525           {
 526             ref_tail_fields = p;
 527             break;
 528           }
 529       for (p = cp; *p; ++p)
 530         continue;
 531       cp_end = p;
 532
 533       explicit_bracketing = false;
 534     }
 535
 536   /* Add all relevant variants. */
 537   {
 538     unsigned symbol_index;
 539     variant_count = 0;
 540     for (symbol_index = 0, l = rule; !symbol_list_null (l);
 541          ++symbol_index, l = l->next)
 542       {
 543         variant *var;
 544         if (l->content_type != SYMLIST_SYMBOL)
 545           continue;
 546
 547         var = variant_add (l->content.sym->tag, l->sym_loc,
 548                            symbol_index, cp, cp_end, explicit_bracketing);
 549         if (var && l->named_ref)
 550           var->hidden_by = l->named_ref;
 551
 552         if (l->named_ref)
 553           variant_add (l->named_ref->id, l->named_ref->loc,
 554                        symbol_index, cp, cp_end, explicit_bracketing);
 555       }
 556   }
 557
 558   /* Check errors. */
 559   for (i = 0; i < variant_count; ++i)
 560     {
 561       variant *var = &variant_table[i];
 562       unsigned symbol_index = var->symbol_index;
 563
 564       /* Check visibility from mid-rule actions. */
 565       if (midrule_rhs_index != 0
 566           && (symbol_index == 0 || midrule_rhs_index < symbol_index))
 567         var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
 568
 569       /* Check correct bracketing. */
 570       if (!explicit_bracketing && contains_dot_or_dash (var->id))
 571         var->err |= VARIANT_BAD_BRACKETING;
 572
 573       /* Check using of hidden symbols. */
 574       if (var->hidden_by)
 575         var->err |= VARIANT_HIDDEN;
 576
 577       if (!var->err)
 578         {
 579           valid_variant_index = i;
 580           ++valid_variants;
 581         }
 582     }
 583
 584   switch (valid_variants)
 585     {
 586     case 0:
 587       {
 588         unsigned len = (explicit_bracketing || !ref_tail_fields) ?
 589           cp_end - cp : ref_tail_fields - cp;
 590         unsigned indent = 0;
 591
 592         complain_at_indent (text_loc, complaint, &indent,
 593                             _("invalid reference: %s"), quote (text));
 594         indent += SUB_INDENT;
 595         if (len == 0)
 596           {
 597             location sym_loc = text_loc;
 598             sym_loc.start.column += 1;
 599             sym_loc.end = sym_loc.start;
 600             complain_at_indent (sym_loc, complaint, &indent,
 601                                 _("syntax error after '%c', expecting integer, "
 602                                   "letter, '_', '[', or '$'"),
 603                                 dollar_or_at);
 604           }
 605         else if (midrule_rhs_index)
 606           complain_at_indent (rule->location, complaint, &indent,
 607                               _("symbol not found in production before $%d: "
 608                                 "%.*s"),
 609                               midrule_rhs_index, len, cp);
 610         else
 611           complain_at_indent (rule->location, complaint, &indent,
 612                               _("symbol not found in production: %.*s"),
 613                               len, cp);
 614
 615         if (variant_count > 0)
 616           show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 617                              dollar_or_at, complaint, indent);
 618         return INVALID_REF;
 619       }
 620     case 1:
 621       {
 622         unsigned indent = 0;
 623         if (variant_count > 1)
 624           {
 625             complain_at_indent (text_loc, Wother, &indent,
 626                                 _("misleading reference: %s"), quote (text));
 627             show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 628                                dollar_or_at, Wother, indent + SUB_INDENT);
 629           }
 630         {
 631           unsigned symbol_index =
 632             variant_table[valid_variant_index].symbol_index;
 633           return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
 634         }
 635       }
 636     case 2:
 637     default:
 638       {
 639         unsigned indent = 0;
 640         complain_at_indent (text_loc, complaint, &indent,
 641                             _("ambiguous reference: %s"), quote (text));
 642         show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 643                            dollar_or_at, complaint, indent + SUB_INDENT);
 644         return INVALID_REF;
 645       }
 646     }
 647
 648   /* Not reachable. */
 649   return INVALID_REF;
 650 }
 651
 652 /* Keeps track of the maximum number of semantic values to the left of
 653    a handle (those referenced by $0, $-1, etc.) are required by the
 654    semantic actions of this grammar. */
 655 int max_left_semantic_context = 0;
 656
 657
 658 /* If CP points to a typename (i.e., <.*?>), set TYPE_NAME to its
 659    beginning (i.e., after the opening "<", and return the pointer
 660    immediately after it.  */
 661
 662 static
 663 char *
 664 fetch_type_name (char *cp, char const **type_name,
 665                  location dollar_loc)
 666 {
 667   if (*cp == '<')
 668     {
 669       *type_name = ++cp;
 670       while (*cp != '>')
 671         ++cp;
 672
 673       /* The '>' symbol will be later replaced by '\0'. Original
 674          'text' is needed for error messages. */
 675       ++cp;
 676       if (untyped_var_seen)
 677         complain_at (dollar_loc, complaint,
 678                      _("explicit type given in untyped grammar"));
 679       tag_seen = true;
 680     }
 681   return cp;
 682 }
 683
 684 /*------------------------------------------------------------------.
 685 | TEXT is pointing to a wannabee semantic value (i.e., a '$').      |
 686 |                                                                   |
 687 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 688 |                                                                   |
 689 | Output to OBSTACK_FOR_STRING a reference to this semantic value.  |
 690 `------------------------------------------------------------------*/
 691
 692 static void
 693 handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 694 {
 695   char const *type_name = NULL;
 696   char *cp = text + 1;
 697   symbol_list *effective_rule;
 698   int effective_rule_length;
 699   int n;
 700
 701   if (rule->midrule_parent_rule)
 702     {
 703       effective_rule = rule->midrule_parent_rule;
 704       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 705     }
 706   else
 707     {
 708       effective_rule = rule;
 709       effective_rule_length = symbol_list_length (rule->next);
 710     }
 711
 712   /* Get the type name if explicit. */
 713   cp = fetch_type_name (cp, &type_name, dollar_loc);
 714
 715   n = parse_ref (cp, effective_rule, effective_rule_length,
 716                  rule->midrule_parent_rhs_index, text, dollar_loc, '$');
 717
 718   /* End type_name. */
 719   if (type_name)
 720     cp[-1] = '\0';
 721
 722   switch (n)
 723     {
 724     case INVALID_REF:
 725       break;
 726
 727     case LHS_REF:
 728       if (!type_name)
 729         type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
 730
 731       if (!type_name)
 732         {
 733           if (union_seen | tag_seen)
 734             {
 735               if (rule->midrule_parent_rule)
 736                 complain_at (dollar_loc, complaint,
 737                              _("$$ for the midrule at $%d of %s"
 738                                " has no declared type"),
 739                              rule->midrule_parent_rhs_index,
 740                              quote (effective_rule->content.sym->tag));
 741               else
 742                 complain_at (dollar_loc, complaint,
 743                              _("$$ of %s has no declared type"),
 744                              quote (rule->content.sym->tag));
 745             }
 746           else
 747             untyped_var_seen = true;
 748         }
 749
 750       obstack_sgrow (&obstack_for_string, "]b4_lhs_value(");
 751       obstack_quote (&obstack_for_string, type_name);
 752       obstack_sgrow (&obstack_for_string, ")[");
 753       rule->action_props.is_value_used = true;
 754       break;
 755
 756     default:
 757       if (max_left_semantic_context < 1 - n)
 758         max_left_semantic_context = 1 - n;
 759       if (!type_name && 0 < n)
 760         type_name =
 761           symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
 762       if (!type_name)
 763         {
 764           if (union_seen | tag_seen)
 765             complain_at (dollar_loc, complaint,
 766                          _("$%s of %s has no declared type"), cp,
 767                          quote (effective_rule->content.sym->tag));
 768           else
 769             untyped_var_seen = true;
 770         }
 771
 772       obstack_printf (&obstack_for_string,
 773                       "]b4_rhs_value(%d, %d, ", effective_rule_length, n);
 774       obstack_quote (&obstack_for_string, type_name);
 775       obstack_sgrow (&obstack_for_string, ")[");
 776       if (n > 0)
 777         symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
 778           true;
 779       break;
 780     }
 781 }
 782
 783
 784 /*------------------------------------------------------.
 785 | TEXT is a location token (i.e., a '@...').  Output to |
 786 | OBSTACK_FOR_STRING a reference to this location.      |
 787 `------------------------------------------------------*/
 788
 789 static void
 790 handle_action_at (symbol_list *rule, char *text, location at_loc)
 791 {
 792   char *cp = text + 1;
 793   symbol_list *effective_rule;
 794   int effective_rule_length;
 795   int n;
 796
 797   if (rule->midrule_parent_rule)
 798     {
 799       effective_rule = rule->midrule_parent_rule;
 800       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 801     }
 802   else
 803     {
 804       effective_rule = rule;
 805       effective_rule_length = symbol_list_length (rule->next);
 806     }
 807
 808   muscle_percent_define_ensure("locations", at_loc, true);
 809
 810   n = parse_ref (cp, effective_rule, effective_rule_length,
 811                        rule->midrule_parent_rhs_index, text, at_loc, '@');
 812   switch (n)
 813     {
 814     case INVALID_REF:
 815       break;
 816
 817     case LHS_REF:
 818       obstack_sgrow (&obstack_for_string, "]b4_lhs_location[");
 819       break;
 820
 821     default:
 822       obstack_printf (&obstack_for_string, "]b4_rhs_location(%d, %d)[",
 823                       effective_rule_length, n);
 824       break;
 825     }
 826 }
 827
 828
 829 /*-------------------------.
 830 | Initialize the scanner.  |
 831 `-------------------------*/
 832
 833 /* Translate the dollars and ats in \a self, in the context \a sc_context
 834    (SC_RULE_ACTION, SC_SYMBOL_ACTION, INITIAL).  */
 835
 836 static char const *
 837 translate_action (code_props *self, int sc_context)
 838 {
 839   char *res;
 840   static bool initialized = false;
 841   if (!initialized)
 842     {
 843       obstack_init (&obstack_for_string);
 844       yy_flex_debug = 0;
 845       initialized = true;
 846     }
 847
 848   loc->start = loc->end = self->location.start;
 849   yy_switch_to_buffer (yy_scan_string (self->code));
 850   res = code_lex (self, sc_context);
 851   yy_delete_buffer (YY_CURRENT_BUFFER);
 852
 853   return res;
 854 }
 855
 856 /*------------------------------------------------------------------------.
 857 | Implementation of the public interface as documented in "scan-code.h".  |
 858 `------------------------------------------------------------------------*/
 859
 860 void
 861 code_props_none_init (code_props *self)
 862 {
 863   *self = code_props_none;
 864 }
 865
 866 code_props code_props_none = CODE_PROPS_NONE_INIT;
 867
 868 void
 869 code_props_plain_init (code_props *self, char const *code,
 870                        location code_loc)
 871 {
 872   code_props_none_init (self);
 873   self->kind = CODE_PROPS_PLAIN;
 874   self->code = code;
 875   self->location = code_loc;
 876 }
 877
 878 void
 879 code_props_symbol_action_init (code_props *self, char const *code,
 880                                location code_loc)
 881 {
 882   code_props_none_init (self);
 883   self->kind = CODE_PROPS_SYMBOL_ACTION;
 884   self->code = code;
 885   self->location = code_loc;
 886 }
 887
 888 void
 889 code_props_rule_action_init (code_props *self, char const *code,
 890                              location code_loc, symbol_list *rule,
 891                              named_ref *name, bool is_predicate)
 892 {
 893   code_props_none_init (self);
 894   self->kind = CODE_PROPS_RULE_ACTION;
 895   self->code = code;
 896   self->location = code_loc;
 897   self->rule = rule;
 898   self->named_ref = name;
 899   self->is_predicate = is_predicate;
 900 }
 901
 902 void
 903 code_props_translate_code (code_props *self)
 904 {
 905   switch (self->kind)
 906     {
 907       case CODE_PROPS_NONE:
 908         break;
 909       case CODE_PROPS_PLAIN:
 910         self->code = translate_action (self, INITIAL);
 911         break;
 912       case CODE_PROPS_SYMBOL_ACTION:
 913         self->code = translate_action (self, SC_SYMBOL_ACTION);
 914         break;
 915       case CODE_PROPS_RULE_ACTION:
 916         self->code = translate_action (self, SC_RULE_ACTION);
 917         break;
 918     }
 919 }
 920
 921 void
 922 code_scanner_last_string_free (void)
 923 {
 924   STRING_FREE;
 925 }
 926
 927 void
 928 code_scanner_free (void)
 929 {
 930   obstack_free (&obstack_for_string, 0);
 931   variant_table_free ();
 932
 933   /* Reclaim Flex's buffers.  */
 934   yylex_destroy ();
 935 }