src/scan-code.l

   1 /* Bison Action Scanner                             -*- C -*-
   2
   3    Copyright (C) 2006-2011 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 void handle_action_dollar (symbol_list *rule, char *cp,
  51                                   location dollar_loc);
  52 static void handle_action_at (symbol_list *rule, char *cp, location at_loc);
  53
  54 /* A string to be pushed to obstack after dollar/at has been handled. */
  55 static char *ref_tail_fields;
  56
  57 static location the_location;
  58 static location *loc = &the_location;
  59
  60 /* A string representing the most recent translation.  */
  61 static char *last_string;
  62
  63 /* True if an untyped $$ or $n was seen.  */
  64 static bool untyped_var_seen;
  65
  66 %}
  67  /* C and C++ comments in code. */
  68 %x SC_COMMENT SC_LINE_COMMENT
  69  /* Strings and characters in code. */
  70 %x SC_STRING SC_CHARACTER
  71  /* Whether in a rule or symbol action.  Specifies the translation
  72     of $ and @.  */
  73 %x SC_RULE_ACTION SC_SYMBOL_ACTION
  74
  75
  76 /* POSIX says that a tag must be both an id and a C union member, but
  77    historically almost any character is allowed in a tag.  We disallow
  78    NUL and newline, as this simplifies our implementation.  */
  79 tag      [^\0\n>]+
  80
  81 /* Zero or more instances of backslash-newline.  Following GCC, allow
  82    white space between the backslash and the newline.  */
  83 splice   (\\[ \f\t\v]*\n)*
  84
  85 /* C style identifier. Must start with letter. Will be used for
  86    named symbol references. Shall be kept synchronized with
  87    scan-gram.l "letter" and "id". */
  88 letter    [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
  89 id        {letter}({letter}|[-0-9])*
  90 ref      -?[0-9]+|{id}|"["{id}"]"|"$"
  91
  92 %%
  93
  94 %{
  95   /* Nesting level of the current code in braces.  */
  96   int braces_level = 0;
  97
  98   /* Whether a semicolon is probably needed.
  99      The heuristic is that a semicolon is not needed after `{', `}', `;',
 100      or a C preprocessor directive, and that whitespaces and comments
 101      do not affect this flag.
 102      Note that `{' does not need a semicolon because of `{}'.
 103      A semicolon may be needed before a cpp direcive, but don't bother.  */
 104   bool need_semicolon = false;
 105
 106   /* Whether in a C preprocessor directive.  Don't use a start condition
 107      for this because, at the end of strings and comments, we still need
 108      to know whether we're in a directive.  */
 109   bool in_cpp = false;
 110
 111   /* This scanner is special: it is invoked only once, henceforth
 112      is expected to return only once.  This initialization is
 113      therefore done once per action to translate. */
 114   aver (sc_context == SC_SYMBOL_ACTION
 115         || sc_context == SC_RULE_ACTION
 116         || sc_context == INITIAL);
 117   BEGIN sc_context;
 118 %}
 119
 120   /*------------------------------------------------------------.
 121   | Scanning a C comment.  The initial `/ *' is already eaten.  |
 122   `------------------------------------------------------------*/
 123
 124 <SC_COMMENT>
 125 {
 126   "*"{splice}"/"  STRING_GROW; BEGIN sc_context;
 127 }
 128
 129
 130   /*--------------------------------------------------------------.
 131   | Scanning a line comment.  The initial `//' is already eaten.  |
 132   `--------------------------------------------------------------*/
 133
 134 <SC_LINE_COMMENT>
 135 {
 136   "\n"           STRING_GROW; BEGIN sc_context;
 137   {splice}       STRING_GROW;
 138 }
 139
 140
 141   /*--------------------------------------------.
 142   | Scanning user-code characters and strings.  |
 143   `--------------------------------------------*/
 144
 145 <SC_CHARACTER,SC_STRING>
 146 {
 147   {splice}|\\{splice}.  STRING_GROW;
 148 }
 149
 150 <SC_CHARACTER>
 151 {
 152   "'"           STRING_GROW; BEGIN sc_context;
 153 }
 154
 155 <SC_STRING>
 156 {
 157   "\""          STRING_GROW; BEGIN sc_context;
 158 }
 159
 160
 161 <SC_RULE_ACTION,SC_SYMBOL_ACTION>{
 162   "'" {
 163     STRING_GROW;
 164     BEGIN SC_CHARACTER;
 165     need_semicolon = true;
 166   }
 167   "\"" {
 168     STRING_GROW;
 169     BEGIN SC_STRING;
 170     need_semicolon = true;
 171   }
 172   "/"{splice}"*" {
 173     STRING_GROW;
 174     BEGIN SC_COMMENT;
 175   }
 176   "/"{splice}"/" {
 177     STRING_GROW;
 178     BEGIN SC_LINE_COMMENT;
 179   }
 180 }
 181
 182 <SC_RULE_ACTION>
 183 {
 184   "$"("<"{tag}">")?{ref}  {
 185     ref_tail_fields = 0;
 186     handle_action_dollar (self->rule, yytext, *loc);
 187     if (ref_tail_fields) {
 188       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 189     }
 190     need_semicolon = true;
 191   }
 192   "@"{ref} {
 193     ref_tail_fields = 0;
 194     handle_action_at (self->rule, yytext, *loc);
 195     if (ref_tail_fields) {
 196       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 197     }
 198     need_semicolon = true;
 199   }
 200   "$"  {
 201     warn_at (*loc, _("stray `$'"));
 202     obstack_sgrow (&obstack_for_string, "$][");
 203     need_semicolon = true;
 204   }
 205   "@"  {
 206     warn_at (*loc, _("stray `@'"));
 207     obstack_sgrow (&obstack_for_string, "@@");
 208     need_semicolon = true;
 209   }
 210   "["  {
 211     obstack_sgrow (&obstack_for_string, "@{");
 212     need_semicolon = true;
 213   }
 214   "]"  {
 215     obstack_sgrow (&obstack_for_string, "@}");
 216     need_semicolon = true;
 217   }
 218
 219   ";"  STRING_GROW;                 need_semicolon = false;
 220   "{"  STRING_GROW; ++braces_level; need_semicolon = false;
 221   "}"  {
 222     bool outer_brace = --braces_level == 0;
 223
 224     /* As an undocumented Bison extension, append `;' before the last
 225        brace in braced code, so that the user code can omit trailing
 226        `;'.  But do not append `;' if emulating Yacc, since Yacc does
 227        not append one.  */
 228     if (outer_brace && !yacc_flag && language_prio == default_prio
 229         && skeleton_prio == default_prio && need_semicolon && ! in_cpp)
 230       {
 231         warn_at (*loc, _("a `;' might be needed at the end of action code"));
 232         warn_at (*loc, _("future versions of Bison will not add the `;'"));
 233         obstack_1grow (&obstack_for_string, ';');
 234       }
 235
 236     STRING_GROW;
 237     need_semicolon = false;
 238   }
 239
 240   /* Preprocessing directives should only be recognized at the beginning
 241      of lines, allowing whitespace including comments, but in C/C++,
 242      `#' can only be the start of preprocessor directives or within
 243      `#define' directives anyway, so don't bother with begin of line.  */
 244   "#"       STRING_GROW; in_cpp = true;
 245
 246   {splice}  STRING_GROW;
 247   [\n\r]    STRING_GROW; if (in_cpp) in_cpp = need_semicolon = false;
 248   [ \t\f]   STRING_GROW;
 249
 250   /* YYFAIL is undocumented and was formally deprecated in Bison
 251      2.4.2.  */
 252   YYFAIL {
 253     STRING_GROW; need_semicolon = true;
 254     warn_at (*loc, _("use of YYFAIL, which is deprecated and will be"
 255                      " removed"));
 256   }
 257
 258   /* The sole purpose of this is to make sure identifiers that merely
 259      contain YYFAIL don't produce the above warning.  */
 260   [A-Za-z_][0-9A-Za-z_]* STRING_GROW; need_semicolon = true;
 261
 262   . STRING_GROW; need_semicolon = true;
 263 }
 264
 265 <SC_SYMBOL_ACTION>
 266 {
 267   "$$" {
 268     obstack_sgrow (&obstack_for_string, "]b4_dollar_dollar[");
 269     self->is_value_used = true;
 270   }
 271   "@$" {
 272     obstack_sgrow (&obstack_for_string, "]b4_at_dollar[");
 273     muscle_percent_define_ensure("locations", the_location, true);
 274   }
 275 }
 276
 277
 278   /*-----------------------------------------.
 279   | Escape M4 quoting characters in C code.  |
 280   `-----------------------------------------*/
 281
 282 <*>
 283 {
 284   \$    obstack_sgrow (&obstack_for_string, "$][");
 285   \@    obstack_sgrow (&obstack_for_string, "@@");
 286   \[    obstack_sgrow (&obstack_for_string, "@{");
 287   \]    obstack_sgrow (&obstack_for_string, "@}");
 288 }
 289
 290   /*-----------------------------------------------------.
 291   | By default, grow the string obstack with the input.  |
 292   `-----------------------------------------------------*/
 293
 294 <*>.|\n STRING_GROW;
 295
 296  /* End of processing. */
 297 <*><<EOF>>       {
 298                    STRING_FINISH;
 299                    return last_string;
 300                  }
 301
 302 %%
 303
 304 static inline bool
 305 is_dot_or_dash (char ch)
 306 {
 307   return ch == '.' || ch == '-';
 308 }
 309
 310 static inline bool
 311 contains_dot_or_dash (const char* p)
 312 {
 313   for (; *p; ++p)
 314     if (is_dot_or_dash (*p))
 315       return true;
 316   return false;
 317 }
 318
 319 /* Defines a variant of a symbolic name resolution. */
 320 typedef struct
 321 {
 322   /* Index in symbol list. */
 323   unsigned symbol_index;
 324
 325   /* Matched symbol id and loc. */
 326   uniqstr id;
 327   location loc;
 328
 329   /* Hiding named reference. */
 330   named_ref* hidden_by;
 331
 332   /* Error flags. May contain zero (no errors) or
 333      a combination of VARIANT_* values. */
 334   unsigned err;
 335 } variant;
 336
 337 /* Set when the variant refers to a symbol hidden
 338    by an explicit symbol reference. */
 339 #define VARIANT_HIDDEN (1 << 0)
 340
 341 /* Set when the variant refers to a symbol containing
 342    dots or dashes. Will require explicit bracketing. */
 343 #define VARIANT_BAD_BRACKETING (1 << 1)
 344
 345 /* Set when the variant refers to a symbol which is
 346    not visible from current midrule. */
 347 #define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
 348
 349 static variant *variant_table = 0;
 350 static unsigned variant_table_size = 0;
 351 static unsigned variant_count = 0;
 352
 353 static variant *
 354 variant_table_grow (void)
 355 {
 356   ++variant_count;
 357   if (variant_count > variant_table_size)
 358     {
 359       while (variant_count > variant_table_size)
 360         variant_table_size = 2 * variant_table_size + 3;
 361       variant_table = xnrealloc (variant_table, variant_table_size,
 362                                  sizeof *variant_table);
 363     }
 364   return &variant_table[variant_count - 1];
 365 }
 366
 367 static void
 368 variant_table_free (void)
 369 {
 370   free (variant_table);
 371   variant_table = 0;
 372   variant_table_size = variant_count = 0;
 373 }
 374
 375 static char *
 376 find_prefix_end (const char *prefix, char *begin, char *end)
 377 {
 378   char *ptr = begin;
 379
 380   for (; *prefix && ptr != end; ++prefix, ++ptr)
 381     if (*prefix != *ptr)
 382       return 0;
 383
 384   if (*prefix)
 385     return 0;
 386
 387   return ptr;
 388 }
 389
 390 static variant *
 391 variant_add (uniqstr id, location id_loc, unsigned symbol_index,
 392              char *cp, char *cp_end, bool explicit_bracketing)
 393 {
 394   char *prefix_end;
 395
 396   prefix_end = find_prefix_end (id, cp, cp_end);
 397   if (prefix_end &&
 398       (prefix_end == cp_end ||
 399        (!explicit_bracketing && is_dot_or_dash (*prefix_end))))
 400     {
 401       variant *r = variant_table_grow ();
 402       r->symbol_index = symbol_index;
 403       r->id = id;
 404       r->loc = id_loc;
 405       r->hidden_by = NULL;
 406       r->err = 0;
 407       return r;
 408     }
 409   else
 410     return NULL;
 411 }
 412
 413 static const char *
 414 get_at_spec(unsigned symbol_index)
 415 {
 416   static char at_buf[20];
 417   if (symbol_index == 0)
 418     strcpy (at_buf, "$$");
 419   else
 420     snprintf (at_buf, sizeof at_buf, "$%u", symbol_index);
 421   return at_buf;
 422 }
 423
 424 static void
 425 show_sub_messages (const char* cp, bool explicit_bracketing,
 426                    int midrule_rhs_index, char dollar_or_at,
 427                    bool is_warning, unsigned indent)
 428 {
 429   unsigned i;
 430
 431   for (i = 0; i < variant_count; ++i)
 432     {
 433       const variant *var = &variant_table[i];
 434       const char *at_spec = get_at_spec (var->symbol_index);
 435
 436       if (var->err == 0)
 437         {
 438           if (is_warning)
 439             warn_at_indent (var->loc, &indent, _("refers to: %c%s at %s"),
 440                             dollar_or_at, var->id, at_spec);
 441           else
 442             complain_at_indent (var->loc, &indent, _("refers to: %c%s at %s"),
 443                                 dollar_or_at, var->id, at_spec);
 444         }
 445       else
 446         {
 447           static struct obstack msg_buf;
 448           const char *tail = explicit_bracketing ? "" :
 449             cp + strlen (var->id);
 450           const char *id = var->hidden_by ? var->hidden_by->id :
 451             var->id;
 452           location id_loc = var->hidden_by ? var->hidden_by->loc :
 453             var->loc;
 454
 455           /* Create the explanation message. */
 456           obstack_init (&msg_buf);
 457
 458           obstack_fgrow1 (&msg_buf, _("possibly meant: %c"), dollar_or_at);
 459           if (contains_dot_or_dash (id))
 460             obstack_fgrow1 (&msg_buf, "[%s]", id);
 461           else
 462             obstack_sgrow (&msg_buf, id);
 463           obstack_sgrow (&msg_buf, tail);
 464
 465           if (var->err & VARIANT_HIDDEN)
 466             {
 467               obstack_fgrow1 (&msg_buf, _(", hiding %c"), dollar_or_at);
 468               if (contains_dot_or_dash (var->id))
 469                 obstack_fgrow1 (&msg_buf, "[%s]", var->id);
 470               else
 471                 obstack_sgrow (&msg_buf, var->id);
 472               obstack_sgrow (&msg_buf, tail);
 473             }
 474
 475           obstack_fgrow1 (&msg_buf, _(" at %s"), at_spec);
 476
 477           if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
 478             {
 479               const char *format =
 480                 _(", cannot be accessed from mid-rule action at $%d");
 481               obstack_fgrow1 (&msg_buf, format, midrule_rhs_index);
 482             }
 483
 484           obstack_1grow (&msg_buf, '\0');
 485           if (is_warning)
 486             warn_at_indent (id_loc, &indent, "%s",
 487                             (char *) obstack_finish (&msg_buf));
 488           else
 489             complain_at_indent (id_loc, &indent, "%s",
 490                                 (char *) obstack_finish (&msg_buf));
 491           obstack_free (&msg_buf, 0);
 492         }
 493     }
 494 }
 495
 496 /* Returned from "parse_ref" when the reference
 497    is inappropriate. */
 498 #define INVALID_REF (INT_MIN)
 499
 500 /* Returned from "parse_ref" when the reference
 501    points to LHS ($$) of the current rule or midrule. */
 502 #define LHS_REF (INT_MIN + 1)
 503
 504 /* Sub-messages indent. */
 505 #define SUB_INDENT (4)
 506
 507 /* Parse named or positional reference. In case of positional
 508    references, can return negative values for $-n "deep" stack
 509    accesses. */
 510 static long int
 511 parse_ref (char *cp, symbol_list *rule, int rule_length,
 512            int midrule_rhs_index, char *text, location text_loc,
 513            char dollar_or_at)
 514 {
 515   symbol_list *l;
 516   char *cp_end;
 517   bool explicit_bracketing;
 518   unsigned i;
 519   unsigned valid_variants = 0;
 520   unsigned valid_variant_index = 0;
 521
 522   if ('$' == *cp)
 523     return LHS_REF;
 524
 525   if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))
 526     {
 527       long int num = strtol (cp, &cp, 10);
 528       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
 529         return num;
 530       else
 531         {
 532           complain_at (text_loc, _("integer out of range: %s"),
 533                        quote (text));
 534           return INVALID_REF;
 535         }
 536     }
 537
 538   if ('[' == *cp)
 539     {
 540       /* Ignore the brackets. */
 541       char *p;
 542       for (p = ++cp; *p != ']'; ++p)
 543         continue;
 544       cp_end = p;
 545
 546       explicit_bracketing = true;
 547     }
 548   else
 549     {
 550       /* Take all characters of the name. */
 551       char* p;
 552       for (p = cp; *p; ++p)
 553         if (is_dot_or_dash (*p))
 554           {
 555             ref_tail_fields = p;
 556             break;
 557           }
 558       for (p = cp; *p; ++p)
 559         continue;
 560       cp_end = p;
 561
 562       explicit_bracketing = false;
 563     }
 564
 565   /* Add all relevant variants. */
 566   {
 567     unsigned symbol_index;
 568     variant_count = 0;
 569     for (symbol_index = 0, l = rule; !symbol_list_null (l);
 570          ++symbol_index, l = l->next)
 571       {
 572         variant *var;
 573         if (l->content_type != SYMLIST_SYMBOL)
 574           continue;
 575
 576         var = variant_add (l->content.sym->tag, l->sym_loc,
 577                            symbol_index, cp, cp_end, explicit_bracketing);
 578         if (var && l->named_ref)
 579           var->hidden_by = l->named_ref;
 580
 581         if (l->named_ref)
 582           variant_add (l->named_ref->id, l->named_ref->loc,
 583                        symbol_index, cp, cp_end, explicit_bracketing);
 584       }
 585   }
 586
 587   /* Check errors. */
 588   for (i = 0; i < variant_count; ++i)
 589     {
 590       variant *var = &variant_table[i];
 591       unsigned symbol_index = var->symbol_index;
 592
 593       /* Check visibility from mid-rule actions. */
 594       if (midrule_rhs_index != 0
 595           && (symbol_index == 0 || midrule_rhs_index < symbol_index))
 596         var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
 597
 598       /* Check correct bracketing. */
 599       if (!explicit_bracketing && contains_dot_or_dash (var->id))
 600         var->err |= VARIANT_BAD_BRACKETING;
 601
 602       /* Check using of hidden symbols. */
 603       if (var->hidden_by)
 604         var->err |= VARIANT_HIDDEN;
 605
 606       if (!var->err)
 607         {
 608           valid_variant_index = i;
 609           ++valid_variants;
 610         }
 611     }
 612
 613   switch (valid_variants)
 614     {
 615     case 0:
 616       {
 617         unsigned len = (explicit_bracketing || !ref_tail_fields) ?
 618           cp_end - cp : ref_tail_fields - cp;
 619         unsigned indent = 0;
 620
 621         complain_at_indent (text_loc, &indent, _("invalid reference: %s"),
 622                             quote (text));
 623         indent += SUB_INDENT;
 624         if (len == 0)
 625           {
 626             location sym_loc = text_loc;
 627             sym_loc.start.column += 1;
 628             sym_loc.end = sym_loc.start;
 629             const char *format =
 630               _("syntax error after `%c', expecting integer, letter,"
 631                 " `_', `[', or `$'");
 632             complain_at_indent (sym_loc, &indent, format, dollar_or_at);
 633           }
 634         else if (midrule_rhs_index)
 635           {
 636             const char *format =
 637               _("symbol not found in production before $%d: %.*s");
 638             complain_at_indent (rule->location, &indent, format,
 639                                 midrule_rhs_index, len, cp);
 640           }
 641         else
 642           {
 643             const char *format =
 644               _("symbol not found in production: %.*s");
 645             complain_at_indent (rule->location, &indent, format,
 646                                 len, cp);
 647           }
 648
 649         if (variant_count > 0)
 650           show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 651                              dollar_or_at, false, indent);
 652         return INVALID_REF;
 653       }
 654     case 1:
 655       {
 656         unsigned indent = 0;
 657         if (variant_count > 1)
 658           {
 659             warn_at_indent (text_loc, &indent, _("misleading reference: %s"),
 660                             quote (text));
 661             show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 662                                dollar_or_at, true, indent + SUB_INDENT);
 663           }
 664         {
 665           unsigned symbol_index =
 666             variant_table[valid_variant_index].symbol_index;
 667           return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
 668         }
 669       }
 670     case 2:
 671     default:
 672       {
 673         unsigned indent = 0;
 674         complain_at_indent (text_loc, &indent, _("ambiguous reference: %s"),
 675                             quote (text));
 676         show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 677                            dollar_or_at, false, indent + SUB_INDENT);
 678         return INVALID_REF;
 679       }
 680     }
 681
 682   /* Not reachable. */
 683   return INVALID_REF;
 684 }
 685
 686 /* Keeps track of the maximum number of semantic values to the left of
 687    a handle (those referenced by $0, $-1, etc.) are required by the
 688    semantic actions of this grammar. */
 689 int max_left_semantic_context = 0;
 690
 691
 692 /*------------------------------------------------------------------.
 693 | TEXT is pointing to a wannabee semantic value (i.e., a `$').      |
 694 |                                                                   |
 695 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 696 |                                                                   |
 697 | Output to OBSTACK_FOR_STRING a reference to this semantic value.  |
 698 `------------------------------------------------------------------*/
 699
 700 static void
 701 handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 702 {
 703   char const *type_name = NULL;
 704   char *cp = text + 1;
 705   char *gt_ptr = 0;
 706   symbol_list *effective_rule;
 707   int effective_rule_length;
 708   int n;
 709
 710   if (rule->midrule_parent_rule)
 711     {
 712       effective_rule = rule->midrule_parent_rule;
 713       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 714     }
 715   else
 716     {
 717       effective_rule = rule;
 718       effective_rule_length = symbol_list_length (rule->next);
 719     }
 720
 721   /* Get the type name if explicit. */
 722   if (*cp == '<')
 723     {
 724       type_name = ++cp;
 725       while (*cp != '>')
 726         ++cp;
 727
 728       /* The '>' symbol will be later replaced by '\0'. Original
 729          'text' is needed for error messages. */
 730       gt_ptr = cp;
 731       ++cp;
 732       if (untyped_var_seen)
 733         complain_at (dollar_loc, _("explicit type given in untyped grammar"));
 734       tag_seen = true;
 735     }
 736
 737   n = parse_ref (cp, effective_rule, effective_rule_length,
 738                  rule->midrule_parent_rhs_index, text, dollar_loc, '$');
 739
 740   if (gt_ptr)
 741     *gt_ptr = '\0';
 742
 743   switch (n)
 744     {
 745     case INVALID_REF:
 746       break;
 747
 748     case LHS_REF:
 749       if (!type_name)
 750         type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
 751
 752       if (!type_name)
 753         {
 754           if (union_seen | tag_seen)
 755             {
 756               if (rule->midrule_parent_rule)
 757                 complain_at (dollar_loc,
 758                              _("$$ for the midrule at $%d of `%s'"
 759                                " has no declared type"),
 760                              rule->midrule_parent_rhs_index,
 761                              effective_rule->content.sym->tag);
 762               else
 763                 complain_at (dollar_loc, _("$$ of `%s' has no declared type"),
 764                              rule->content.sym->tag);
 765             }
 766           else
 767             untyped_var_seen = true;
 768           type_name = "";
 769         }
 770
 771       obstack_fgrow1 (&obstack_for_string,
 772                       "]b4_lhs_value([%s])[", type_name);
 773       rule->action_props.is_value_used = true;
 774       break;
 775
 776     default:
 777       if (max_left_semantic_context < 1 - n)
 778         max_left_semantic_context = 1 - n;
 779       if (!type_name && 0 < n)
 780         type_name =
 781           symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
 782       if (!type_name)
 783         {
 784           if (union_seen | tag_seen)
 785             complain_at (dollar_loc, _("$%s of `%s' has no declared type"),
 786                          cp, effective_rule->content.sym->tag);
 787           else
 788             untyped_var_seen = true;
 789           type_name = "";
 790         }
 791
 792       obstack_fgrow3 (&obstack_for_string,
 793                       "]b4_rhs_value(%d, %d, [%s])[",
 794                       effective_rule_length, n, type_name);
 795       if (n > 0)
 796         symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
 797           true;
 798       break;
 799     }
 800 }
 801
 802
 803 /*------------------------------------------------------.
 804 | TEXT is a location token (i.e., a `@...').  Output to |
 805 | OBSTACK_FOR_STRING a reference to this location.      |
 806 `------------------------------------------------------*/
 807
 808 static void
 809 handle_action_at (symbol_list *rule, char *text, location at_loc)
 810 {
 811   char *cp = text + 1;
 812   symbol_list *effective_rule;
 813   int effective_rule_length;
 814   int n;
 815
 816   if (rule->midrule_parent_rule)
 817     {
 818       effective_rule = rule->midrule_parent_rule;
 819       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 820     }
 821   else
 822     {
 823       effective_rule = rule;
 824       effective_rule_length = symbol_list_length (rule->next);
 825     }
 826
 827   muscle_percent_define_ensure("locations", at_loc, true);
 828
 829   n = parse_ref (cp, effective_rule, effective_rule_length,
 830                        rule->midrule_parent_rhs_index, text, at_loc, '@');
 831   switch (n)
 832     {
 833     case INVALID_REF:
 834       break;
 835
 836     case LHS_REF:
 837       obstack_sgrow (&obstack_for_string, "]b4_lhs_location[");
 838       break;
 839
 840     default:
 841       obstack_fgrow2 (&obstack_for_string, "]b4_rhs_location(%d, %d)[",
 842                       effective_rule_length, n);
 843       break;
 844     }
 845 }
 846
 847
 848 /*-------------------------.
 849 | Initialize the scanner.  |
 850 `-------------------------*/
 851
 852 /* Translate the dollars and ats in \a self, in the context \a sc_context
 853    (SC_RULE_ACTION, SC_SYMBOL_ACTION, INITIAL).  */
 854
 855 static char const *
 856 translate_action (code_props *self, int sc_context)
 857 {
 858   char *res;
 859   static bool initialized = false;
 860   if (!initialized)
 861     {
 862       obstack_init (&obstack_for_string);
 863       yy_flex_debug = 0;
 864       initialized = true;
 865     }
 866
 867   loc->start = loc->end = self->location.start;
 868   yy_switch_to_buffer (yy_scan_string (self->code));
 869   res = code_lex (self, sc_context);
 870   yy_delete_buffer (YY_CURRENT_BUFFER);
 871
 872   return res;
 873 }
 874
 875 /*------------------------------------------------------------------------.
 876 | Implementation of the public interface as documented in "scan-code.h".  |
 877 `------------------------------------------------------------------------*/
 878
 879 void
 880 code_props_none_init (code_props *self)
 881 {
 882   *self = code_props_none;
 883 }
 884
 885 code_props const code_props_none = CODE_PROPS_NONE_INIT;
 886
 887 void
 888 code_props_plain_init (code_props *self, char const *code,
 889                        location code_loc)
 890 {
 891   self->kind = CODE_PROPS_PLAIN;
 892   self->code = code;
 893   self->location = code_loc;
 894   self->is_value_used = false;
 895   self->rule = NULL;
 896   self->named_ref = NULL;
 897 }
 898
 899 void
 900 code_props_symbol_action_init (code_props *self, char const *code,
 901                                location code_loc)
 902 {
 903   self->kind = CODE_PROPS_SYMBOL_ACTION;
 904   self->code = code;
 905   self->location = code_loc;
 906   self->is_value_used = false;
 907   self->rule = NULL;
 908   self->named_ref = NULL;
 909 }
 910
 911 void
 912 code_props_rule_action_init (code_props *self, char const *code,
 913                              location code_loc, symbol_list *rule,
 914                              named_ref *name, bool is_predicate)
 915 {
 916   self->kind = CODE_PROPS_RULE_ACTION;
 917   self->code = code;
 918   self->location = code_loc;
 919   self->is_value_used = false;
 920   self->rule = rule;
 921   self->named_ref = name;
 922   self->is_predicate = is_predicate;
 923 }
 924
 925 void
 926 code_props_translate_code (code_props *self)
 927 {
 928   switch (self->kind)
 929     {
 930       case CODE_PROPS_NONE:
 931         break;
 932       case CODE_PROPS_PLAIN:
 933         self->code = translate_action (self, INITIAL);
 934         break;
 935       case CODE_PROPS_SYMBOL_ACTION:
 936         self->code = translate_action (self, SC_SYMBOL_ACTION);
 937         break;
 938       case CODE_PROPS_RULE_ACTION:
 939         self->code = translate_action (self, SC_RULE_ACTION);
 940         break;
 941     }
 942 }
 943
 944 void
 945 code_scanner_last_string_free (void)
 946 {
 947   STRING_FREE;
 948 }
 949
 950 void
 951 code_scanner_free (void)
 952 {
 953   obstack_free (&obstack_for_string, 0);
 954   variant_table_free ();
 955
 956   /* Reclaim Flex's buffers.  */
 957   yylex_destroy ();
 958 }