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 "flex-scanner.h"
  31
  32 #include "complain.h"
  33 #include "reader.h"
  34 #include "getargs.h"
  35 #include "scan-code.h"
  36 #include "symlist.h"
  37
  38 #include <c-ctype.h>
  39 #include <get-errno.h>
  40 #include <quote.h>
  41
  42 /* The current calling start condition: SC_RULE_ACTION or
  43    SC_SYMBOL_ACTION. */
  44 # define YY_DECL static char *code_lex (code_props *self, int sc_context)
  45 YY_DECL;
  46
  47 #define YY_USER_ACTION  location_compute (loc, &loc->end, yytext, yyleng);
  48
  49 static void handle_action_dollar (symbol_list *rule, char *cp,
  50                                   location dollar_loc);
  51 static void handle_action_at (symbol_list *rule, char *cp, location at_loc);
  52
  53 /* A string to be pushed to obstack after dollar/at has been handled. */
  54 static char *ref_tail_fields;
  55
  56 static location the_location;
  57 static location *loc = &the_location;
  58
  59 /* A string representing the most recent translation.  */
  60 static char *last_string;
  61
  62 /* True if an untyped $$ or $n was seen.  */
  63 static bool untyped_var_seen;
  64
  65 %}
  66  /* C and C++ comments in code. */
  67 %x SC_COMMENT SC_LINE_COMMENT
  68  /* Strings and characters in code. */
  69 %x SC_STRING SC_CHARACTER
  70  /* Whether in a rule or symbol action.  Specifies the translation
  71     of $ and @.  */
  72 %x SC_RULE_ACTION SC_SYMBOL_ACTION
  73
  74
  75 /* POSIX says that a tag must be both an id and a C union member, but
  76    historically almost any character is allowed in a tag.  We disallow
  77    NUL and newline, as this simplifies our implementation.  */
  78 tag      [^\0\n>]+
  79
  80 /* Zero or more instances of backslash-newline.  Following GCC, allow
  81    white space between the backslash and the newline.  */
  82 splice   (\\[ \f\t\v]*\n)*
  83
  84 /* C style identifier. Must start with letter. Will be used for
  85    named symbol references. Shall be kept synchronized with
  86    scan-gram.l "letter" and "id". */
  87 letter    [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
  88 id        {letter}({letter}|[-0-9])*
  89 ref      -?[0-9]+|{id}|"["{id}"]"|"$"
  90
  91 %%
  92
  93 %{
  94   /* Nesting level of the current code in braces.  */
  95   int braces_level = 0;
  96
  97   /* Whether a semicolon is probably needed.
  98      The heuristic is that a semicolon is not needed after '{', '}', ';',
  99      or a C preprocessor directive, and that whitespaces and comments
 100      do not affect this flag.
 101      Note that '{' does not need a semicolon because of '{}'.
 102      A semicolon may be needed before a cpp direcive, but don't bother.  */
 103   bool need_semicolon = false;
 104
 105   /* Whether in a C preprocessor directive.  Don't use a start condition
 106      for this because, at the end of strings and comments, we still need
 107      to know whether we're in a directive.  */
 108   bool in_cpp = false;
 109
 110   /* This scanner is special: it is invoked only once, henceforth
 111      is expected to return only once.  This initialization is
 112      therefore done once per action to translate. */
 113   aver (sc_context == SC_SYMBOL_ACTION
 114         || sc_context == SC_RULE_ACTION
 115         || sc_context == INITIAL);
 116   BEGIN sc_context;
 117 %}
 118
 119   /*------------------------------------------------------------.
 120   | Scanning a C comment.  The initial '/ *' is already eaten.  |
 121   `------------------------------------------------------------*/
 122
 123 <SC_COMMENT>
 124 {
 125   "*"{splice}"/"  STRING_GROW; BEGIN sc_context;
 126 }
 127
 128
 129   /*--------------------------------------------------------------.
 130   | Scanning a line comment.  The initial '//' is already eaten.  |
 131   `--------------------------------------------------------------*/
 132
 133 <SC_LINE_COMMENT>
 134 {
 135   "\n"           STRING_GROW; BEGIN sc_context;
 136   {splice}       STRING_GROW;
 137 }
 138
 139
 140   /*--------------------------------------------.
 141   | Scanning user-code characters and strings.  |
 142   `--------------------------------------------*/
 143
 144 <SC_CHARACTER,SC_STRING>
 145 {
 146   {splice}|\\{splice}.  STRING_GROW;
 147 }
 148
 149 <SC_CHARACTER>
 150 {
 151   "'"           STRING_GROW; BEGIN sc_context;
 152 }
 153
 154 <SC_STRING>
 155 {
 156   "\""          STRING_GROW; BEGIN sc_context;
 157 }
 158
 159
 160 <SC_RULE_ACTION,SC_SYMBOL_ACTION>{
 161   "'" {
 162     STRING_GROW;
 163     BEGIN SC_CHARACTER;
 164     need_semicolon = true;
 165   }
 166   "\"" {
 167     STRING_GROW;
 168     BEGIN SC_STRING;
 169     need_semicolon = true;
 170   }
 171   "/"{splice}"*" {
 172     STRING_GROW;
 173     BEGIN SC_COMMENT;
 174   }
 175   "/"{splice}"/" {
 176     STRING_GROW;
 177     BEGIN SC_LINE_COMMENT;
 178   }
 179 }
 180
 181 <SC_RULE_ACTION>
 182 {
 183   "$"("<"{tag}">")?{ref}  {
 184     ref_tail_fields = 0;
 185     handle_action_dollar (self->rule, yytext, *loc);
 186     if (ref_tail_fields) {
 187       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 188     }
 189     need_semicolon = true;
 190   }
 191   "@"{ref} {
 192     ref_tail_fields = 0;
 193     handle_action_at (self->rule, yytext, *loc);
 194     if (ref_tail_fields) {
 195       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 196     }
 197     need_semicolon = true;
 198   }
 199   "$"  {
 200     warn_at (*loc, _("stray '$'"));
 201     obstack_sgrow (&obstack_for_string, "$][");
 202     need_semicolon = true;
 203   }
 204   "@"  {
 205     warn_at (*loc, _("stray '@'"));
 206     obstack_sgrow (&obstack_for_string, "@@");
 207     need_semicolon = true;
 208   }
 209   "["  {
 210     obstack_sgrow (&obstack_for_string, "@{");
 211     need_semicolon = true;
 212   }
 213   "]"  {
 214     obstack_sgrow (&obstack_for_string, "@}");
 215     need_semicolon = true;
 216   }
 217
 218   ";"  STRING_GROW;                 need_semicolon = false;
 219   "{"  STRING_GROW; ++braces_level; need_semicolon = false;
 220   "}"  {
 221     bool outer_brace = --braces_level == 0;
 222
 223     /* As an undocumented Bison extension, append ';' before the last
 224        brace in braced code, so that the user code can omit trailing
 225        ';'.  But do not append ';' if emulating Yacc, since Yacc does
 226        not append one.  */
 227     if (outer_brace && !yacc_flag && language_prio == default_prio
 228         && skeleton_prio == default_prio && need_semicolon && ! in_cpp)
 229       {
 230         warn_at (*loc, _("a ';' might be needed at the end of action code"));
 231         warn_at (*loc, _("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
 249   /* YYFAIL is undocumented and was formally deprecated in Bison
 250      2.4.2.  */
 251   YYFAIL {
 252     STRING_GROW; need_semicolon = true;
 253     warn_at (*loc, _("use of YYFAIL, which is deprecated and will be"
 254                      " removed"));
 255   }
 256
 257   /* The sole purpose of this is to make sure identifiers that merely
 258      contain YYFAIL don't produce the above warning.  */
 259   [A-Za-z_][0-9A-Za-z_]* STRING_GROW; need_semicolon = true;
 260
 261   . STRING_GROW; need_semicolon = true;
 262 }
 263
 264 <SC_SYMBOL_ACTION>
 265 {
 266   "$$" {
 267     obstack_sgrow (&obstack_for_string, "]b4_dollar_dollar[");
 268     self->is_value_used = true;
 269   }
 270   "@$" {
 271     obstack_sgrow (&obstack_for_string, "]b4_at_dollar[");
 272     locations_flag = true;
 273   }
 274 }
 275
 276
 277   /*-----------------------------------------.
 278   | Escape M4 quoting characters in C code.  |
 279   `-----------------------------------------*/
 280
 281 <*>
 282 {
 283   \$    obstack_sgrow (&obstack_for_string, "$][");
 284   \@    obstack_sgrow (&obstack_for_string, "@@");
 285   \[    obstack_sgrow (&obstack_for_string, "@{");
 286   \]    obstack_sgrow (&obstack_for_string, "@}");
 287 }
 288
 289   /*-----------------------------------------------------.
 290   | By default, grow the string obstack with the input.  |
 291   `-----------------------------------------------------*/
 292
 293 <*>.|\n STRING_GROW;
 294
 295  /* End of processing. */
 296 <*><<EOF>>       {
 297                    STRING_FINISH;
 298                    return last_string;
 299                  }
 300
 301 %%
 302
 303 static inline bool
 304 is_dot_or_dash (char ch)
 305 {
 306   return ch == '.' || ch == '-';
 307 }
 308
 309 static inline bool
 310 contains_dot_or_dash (const char* p)
 311 {
 312   for (; *p; ++p)
 313     if (is_dot_or_dash (*p))
 314       return true;
 315   return false;
 316 }
 317
 318 /* Defines a variant of a symbolic name resolution. */
 319 typedef struct
 320 {
 321   /* Index in symbol list. */
 322   unsigned symbol_index;
 323
 324   /* Matched symbol id and loc. */
 325   uniqstr id;
 326   location loc;
 327
 328   /* Hiding named reference. */
 329   named_ref* hidden_by;
 330
 331   /* Error flags. May contain zero (no errors) or
 332      a combination of VARIANT_* values. */
 333   unsigned err;
 334 } variant;
 335
 336 /* Set when the variant refers to a symbol hidden
 337    by an explicit symbol reference. */
 338 #define VARIANT_HIDDEN (1 << 0)
 339
 340 /* Set when the variant refers to a symbol containing
 341    dots or dashes. Will require explicit bracketing. */
 342 #define VARIANT_BAD_BRACKETING (1 << 1)
 343
 344 /* Set when the variant refers to a symbol which is
 345    not visible from current midrule. */
 346 #define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
 347
 348 static variant *variant_table = 0;
 349 static unsigned variant_table_size = 0;
 350 static unsigned variant_count = 0;
 351
 352 static variant *
 353 variant_table_grow (void)
 354 {
 355   ++variant_count;
 356   if (variant_count > variant_table_size)
 357     {
 358       while (variant_count > variant_table_size)
 359         variant_table_size = 2 * variant_table_size + 3;
 360       variant_table = xnrealloc (variant_table, variant_table_size,
 361                                  sizeof *variant_table);
 362     }
 363   return &variant_table[variant_count - 1];
 364 }
 365
 366 static void
 367 variant_table_free (void)
 368 {
 369   free (variant_table);
 370   variant_table = 0;
 371   variant_table_size = variant_count = 0;
 372 }
 373
 374 static char *
 375 find_prefix_end (const char *prefix, char *begin, char *end)
 376 {
 377   char *ptr = begin;
 378
 379   for (; *prefix && ptr != end; ++prefix, ++ptr)
 380     if (*prefix != *ptr)
 381       return 0;
 382
 383   if (*prefix)
 384     return 0;
 385
 386   return ptr;
 387 }
 388
 389 static variant *
 390 variant_add (uniqstr id, location id_loc, unsigned symbol_index,
 391              char *cp, char *cp_end, bool explicit_bracketing)
 392 {
 393   char *prefix_end;
 394
 395   prefix_end = find_prefix_end (id, cp, cp_end);
 396   if (prefix_end &&
 397       (prefix_end == cp_end ||
 398        (!explicit_bracketing && is_dot_or_dash (*prefix_end))))
 399     {
 400       variant *r = variant_table_grow ();
 401       r->symbol_index = symbol_index;
 402       r->id = id;
 403       r->loc = id_loc;
 404       r->hidden_by = NULL;
 405       r->err = 0;
 406       return r;
 407     }
 408   else
 409     return NULL;
 410 }
 411
 412 static const char *
 413 get_at_spec(unsigned symbol_index)
 414 {
 415   static char at_buf[20];
 416   if (symbol_index == 0)
 417     strcpy (at_buf, "$$");
 418   else
 419     snprintf (at_buf, sizeof at_buf, "$%u", symbol_index);
 420   return at_buf;
 421 }
 422
 423 static void
 424 show_sub_messages (const char* cp, bool explicit_bracketing,
 425                    int midrule_rhs_index, char dollar_or_at,
 426                    bool is_warning, unsigned indent)
 427 {
 428   unsigned i;
 429
 430   for (i = 0; i < variant_count; ++i)
 431     {
 432       const variant *var = &variant_table[i];
 433       const char *at_spec = get_at_spec (var->symbol_index);
 434
 435       if (var->err == 0)
 436         {
 437           if (is_warning)
 438             warn_at_indent (var->loc, &indent, _("refers to: %c%s at %s"),
 439                             dollar_or_at, var->id, at_spec);
 440           else
 441             complain_at_indent (var->loc, &indent, _("refers to: %c%s at %s"),
 442                                 dollar_or_at, var->id, at_spec);
 443         }
 444       else
 445         {
 446           static struct obstack msg_buf;
 447           const char *tail = explicit_bracketing ? "" :
 448             cp + strlen (var->id);
 449           const char *id = var->hidden_by ? var->hidden_by->id :
 450             var->id;
 451           location id_loc = var->hidden_by ? var->hidden_by->loc :
 452             var->loc;
 453
 454           /* Create the explanation message. */
 455           obstack_init (&msg_buf);
 456
 457           obstack_fgrow1 (&msg_buf, _("possibly meant: %c"), dollar_or_at);
 458           if (contains_dot_or_dash (id))
 459             obstack_fgrow1 (&msg_buf, "[%s]", id);
 460           else
 461             obstack_sgrow (&msg_buf, id);
 462           obstack_sgrow (&msg_buf, tail);
 463
 464           if (var->err & VARIANT_HIDDEN)
 465             {
 466               obstack_fgrow1 (&msg_buf, _(", hiding %c"), dollar_or_at);
 467               if (contains_dot_or_dash (var->id))
 468                 obstack_fgrow1 (&msg_buf, "[%s]", var->id);
 469               else
 470                 obstack_sgrow (&msg_buf, var->id);
 471               obstack_sgrow (&msg_buf, tail);
 472             }
 473
 474           obstack_fgrow1 (&msg_buf, _(" at %s"), at_spec);
 475
 476           if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
 477             {
 478               const char *format =
 479                 _(", cannot be accessed from mid-rule action at $%d");
 480               obstack_fgrow1 (&msg_buf, format, midrule_rhs_index);
 481             }
 482
 483           obstack_1grow (&msg_buf, '\0');
 484           if (is_warning)
 485             warn_at_indent (id_loc, &indent, "%s",
 486                             (char *) obstack_finish (&msg_buf));
 487           else
 488             complain_at_indent (id_loc, &indent, "%s",
 489                                 (char *) obstack_finish (&msg_buf));
 490           obstack_free (&msg_buf, 0);
 491         }
 492     }
 493 }
 494
 495 /* Returned from "parse_ref" when the reference
 496    is inappropriate. */
 497 #define INVALID_REF (INT_MIN)
 498
 499 /* Returned from "parse_ref" when the reference
 500    points to LHS ($$) of the current rule or midrule. */
 501 #define LHS_REF (INT_MIN + 1)
 502
 503 /* Sub-messages indent. */
 504 #define SUB_INDENT (4)
 505
 506 /* Parse named or positional reference. In case of positional
 507    references, can return negative values for $-n "deep" stack
 508    accesses. */
 509 static long int
 510 parse_ref (char *cp, symbol_list *rule, int rule_length,
 511            int midrule_rhs_index, char *text, location text_loc,
 512            char dollar_or_at)
 513 {
 514   symbol_list *l;
 515   char *cp_end;
 516   bool explicit_bracketing;
 517   unsigned i;
 518   unsigned valid_variants = 0;
 519   unsigned valid_variant_index = 0;
 520
 521   if ('$' == *cp)
 522     return LHS_REF;
 523
 524   if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))
 525     {
 526       long int num = strtol (cp, &cp, 10);
 527       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
 528         return num;
 529       else
 530         {
 531           complain_at (text_loc, _("integer out of range: %s"),
 532                        quote (text));
 533           return INVALID_REF;
 534         }
 535     }
 536
 537   if ('[' == *cp)
 538     {
 539       /* Ignore the brackets. */
 540       char *p;
 541       for (p = ++cp; *p != ']'; ++p)
 542         continue;
 543       cp_end = p;
 544
 545       explicit_bracketing = true;
 546     }
 547   else
 548     {
 549       /* Take all characters of the name. */
 550       char* p;
 551       for (p = cp; *p; ++p)
 552         if (is_dot_or_dash (*p))
 553           {
 554             ref_tail_fields = p;
 555             break;
 556           }
 557       for (p = cp; *p; ++p)
 558         continue;
 559       cp_end = p;
 560
 561       explicit_bracketing = false;
 562     }
 563
 564   /* Add all relevant variants. */
 565   {
 566     unsigned symbol_index;
 567     variant_count = 0;
 568     for (symbol_index = 0, l = rule; !symbol_list_null (l);
 569          ++symbol_index, l = l->next)
 570       {
 571         variant *var;
 572         if (l->content_type != SYMLIST_SYMBOL)
 573           continue;
 574
 575         var = variant_add (l->content.sym->tag, l->sym_loc,
 576                            symbol_index, cp, cp_end, explicit_bracketing);
 577         if (var && l->named_ref)
 578           var->hidden_by = l->named_ref;
 579
 580         if (l->named_ref)
 581           variant_add (l->named_ref->id, l->named_ref->loc,
 582                        symbol_index, cp, cp_end, explicit_bracketing);
 583       }
 584   }
 585
 586   /* Check errors. */
 587   for (i = 0; i < variant_count; ++i)
 588     {
 589       variant *var = &variant_table[i];
 590       unsigned symbol_index = var->symbol_index;
 591
 592       /* Check visibility from mid-rule actions. */
 593       if (midrule_rhs_index != 0
 594           && (symbol_index == 0 || midrule_rhs_index < symbol_index))
 595         var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
 596
 597       /* Check correct bracketing. */
 598       if (!explicit_bracketing && contains_dot_or_dash (var->id))
 599         var->err |= VARIANT_BAD_BRACKETING;
 600
 601       /* Check using of hidden symbols. */
 602       if (var->hidden_by)
 603         var->err |= VARIANT_HIDDEN;
 604
 605       if (!var->err)
 606         {
 607           valid_variant_index = i;
 608           ++valid_variants;
 609         }
 610     }
 611
 612   switch (valid_variants)
 613     {
 614     case 0:
 615       {
 616         unsigned len = (explicit_bracketing || !ref_tail_fields) ?
 617           cp_end - cp : ref_tail_fields - cp;
 618         unsigned indent = 0;
 619
 620         complain_at_indent (text_loc, &indent, _("invalid reference: %s"),
 621                             quote (text));
 622         indent += SUB_INDENT;
 623         if (len == 0)
 624           {
 625             location sym_loc = text_loc;
 626             sym_loc.start.column += 1;
 627             sym_loc.end = sym_loc.start;
 628             const char *format =
 629               _("syntax error after '%c', expecting integer, letter,"
 630                 " '_', '[', or '$'");
 631             complain_at_indent (sym_loc, &indent, format, dollar_or_at);
 632           }
 633         else if (midrule_rhs_index)
 634           {
 635             const char *format =
 636               _("symbol not found in production before $%d: %.*s");
 637             complain_at_indent (rule->location, &indent, format,
 638                                 midrule_rhs_index, len, cp);
 639           }
 640         else
 641           {
 642             const char *format =
 643               _("symbol not found in production: %.*s");
 644             complain_at_indent (rule->location, &indent, format,
 645                                 len, cp);
 646           }
 647
 648         if (variant_count > 0)
 649           show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 650                              dollar_or_at, false, indent);
 651         return INVALID_REF;
 652       }
 653     case 1:
 654       {
 655         unsigned indent = 0;
 656         if (variant_count > 1)
 657           {
 658             warn_at_indent (text_loc, &indent, _("misleading reference: %s"),
 659                             quote (text));
 660             show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 661                                dollar_or_at, true, indent + SUB_INDENT);
 662           }
 663         {
 664           unsigned symbol_index =
 665             variant_table[valid_variant_index].symbol_index;
 666           return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
 667         }
 668       }
 669     case 2:
 670     default:
 671       {
 672         unsigned indent = 0;
 673         complain_at_indent (text_loc, &indent, _("ambiguous reference: %s"),
 674                             quote (text));
 675         show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 676                            dollar_or_at, false, indent + SUB_INDENT);
 677         return INVALID_REF;
 678       }
 679     }
 680
 681   /* Not reachable. */
 682   return INVALID_REF;
 683 }
 684
 685 /* Keeps track of the maximum number of semantic values to the left of
 686    a handle (those referenced by $0, $-1, etc.) are required by the
 687    semantic actions of this grammar. */
 688 int max_left_semantic_context = 0;
 689
 690
 691 /*------------------------------------------------------------------.
 692 | TEXT is pointing to a wannabee semantic value (i.e., a '$').      |
 693 |                                                                   |
 694 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 695 |                                                                   |
 696 | Output to OBSTACK_FOR_STRING a reference to this semantic value.  |
 697 `------------------------------------------------------------------*/
 698
 699 static void
 700 handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 701 {
 702   char const *type_name = NULL;
 703   char *cp = text + 1;
 704   char *gt_ptr = 0;
 705   symbol_list *effective_rule;
 706   int effective_rule_length;
 707   int n;
 708
 709   if (rule->midrule_parent_rule)
 710     {
 711       effective_rule = rule->midrule_parent_rule;
 712       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 713     }
 714   else
 715     {
 716       effective_rule = rule;
 717       effective_rule_length = symbol_list_length (rule->next);
 718     }
 719
 720   /* Get the type name if explicit. */
 721   if (*cp == '<')
 722     {
 723       type_name = ++cp;
 724       while (*cp != '>')
 725         ++cp;
 726
 727       /* The '>' symbol will be later replaced by '\0'. Original
 728          'text' is needed for error messages. */
 729       gt_ptr = cp;
 730       ++cp;
 731       if (untyped_var_seen)
 732         complain_at (dollar_loc, _("explicit type given in untyped grammar"));
 733       tag_seen = true;
 734     }
 735
 736   n = parse_ref (cp, effective_rule, effective_rule_length,
 737                  rule->midrule_parent_rhs_index, text, dollar_loc, '$');
 738
 739   if (gt_ptr)
 740     *gt_ptr = '\0';
 741
 742   switch (n)
 743     {
 744     case INVALID_REF:
 745       break;
 746
 747     case LHS_REF:
 748       if (!type_name)
 749         type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
 750
 751       if (!type_name)
 752         {
 753           if (union_seen | tag_seen)
 754             {
 755               if (rule->midrule_parent_rule)
 756                 complain_at (dollar_loc,
 757                              _("$$ for the midrule at $%d of %s"
 758                                " has no declared type"),
 759                              rule->midrule_parent_rhs_index,
 760                              quote (effective_rule->content.sym->tag));
 761               else
 762                 complain_at (dollar_loc, _("$$ of %s has no declared type"),
 763                              quote (rule->content.sym->tag));
 764             }
 765           else
 766             untyped_var_seen = true;
 767           type_name = "";
 768         }
 769
 770       obstack_fgrow1 (&obstack_for_string,
 771                       "]b4_lhs_value([%s])[", type_name);
 772       rule->action_props.is_value_used = true;
 773       break;
 774
 775     default:
 776       if (max_left_semantic_context < 1 - n)
 777         max_left_semantic_context = 1 - n;
 778       if (!type_name && 0 < n)
 779         type_name =
 780           symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
 781       if (!type_name)
 782         {
 783           if (union_seen | tag_seen)
 784             complain_at (dollar_loc, _("$%s of %s has no declared type"),
 785                          cp, quote (effective_rule->content.sym->tag));
 786           else
 787             untyped_var_seen = true;
 788           type_name = "";
 789         }
 790
 791       obstack_fgrow3 (&obstack_for_string,
 792                       "]b4_rhs_value(%d, %d, [%s])[",
 793                       effective_rule_length, n, type_name);
 794       if (n > 0)
 795         symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
 796           true;
 797       break;
 798     }
 799 }
 800
 801
 802 /*------------------------------------------------------.
 803 | TEXT is a location token (i.e., a '@...').  Output to |
 804 | OBSTACK_FOR_STRING a reference to this location.      |
 805 `------------------------------------------------------*/
 806
 807 static void
 808 handle_action_at (symbol_list *rule, char *text, location at_loc)
 809 {
 810   char *cp = text + 1;
 811   symbol_list *effective_rule;
 812   int effective_rule_length;
 813   int n;
 814
 815   if (rule->midrule_parent_rule)
 816     {
 817       effective_rule = rule->midrule_parent_rule;
 818       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 819     }
 820   else
 821     {
 822       effective_rule = rule;
 823       effective_rule_length = symbol_list_length (rule->next);
 824     }
 825
 826   locations_flag = true;
 827
 828   n = parse_ref (cp, effective_rule, effective_rule_length,
 829                        rule->midrule_parent_rhs_index, text, at_loc, '@');
 830   switch (n)
 831     {
 832     case INVALID_REF:
 833       break;
 834
 835     case LHS_REF:
 836       obstack_sgrow (&obstack_for_string, "]b4_lhs_location[");
 837       break;
 838
 839     default:
 840       obstack_fgrow2 (&obstack_for_string, "]b4_rhs_location(%d, %d)[",
 841                       effective_rule_length, n);
 842       break;
 843     }
 844 }
 845
 846
 847 /*-------------------------.
 848 | Initialize the scanner.  |
 849 `-------------------------*/
 850
 851 /* Translate the dollars and ats in \a self, in the context \a sc_context
 852    (SC_RULE_ACTION, SC_SYMBOL_ACTION, INITIAL).  */
 853
 854 static char const *
 855 translate_action (code_props *self, int sc_context)
 856 {
 857   char *res;
 858   static bool initialized = false;
 859   if (!initialized)
 860     {
 861       obstack_init (&obstack_for_string);
 862       yy_flex_debug = 0;
 863       initialized = true;
 864     }
 865
 866   loc->start = loc->end = self->location.start;
 867   yy_switch_to_buffer (yy_scan_string (self->code));
 868   res = code_lex (self, sc_context);
 869   yy_delete_buffer (YY_CURRENT_BUFFER);
 870
 871   return res;
 872 }
 873
 874 /*------------------------------------------------------------------------.
 875 | Implementation of the public interface as documented in "scan-code.h".  |
 876 `------------------------------------------------------------------------*/
 877
 878 void
 879 code_props_none_init (code_props *self)
 880 {
 881   *self = code_props_none;
 882 }
 883
 884 code_props const code_props_none = CODE_PROPS_NONE_INIT;
 885
 886 void
 887 code_props_plain_init (code_props *self, char const *code,
 888                        location code_loc)
 889 {
 890   self->kind = CODE_PROPS_PLAIN;
 891   self->code = code;
 892   self->location = code_loc;
 893   self->is_value_used = false;
 894   self->rule = NULL;
 895   self->named_ref = NULL;
 896 }
 897
 898 void
 899 code_props_symbol_action_init (code_props *self, char const *code,
 900                                location code_loc)
 901 {
 902   self->kind = CODE_PROPS_SYMBOL_ACTION;
 903   self->code = code;
 904   self->location = code_loc;
 905   self->is_value_used = false;
 906   self->rule = NULL;
 907   self->named_ref = NULL;
 908 }
 909
 910 void
 911 code_props_rule_action_init (code_props *self, char const *code,
 912                              location code_loc, symbol_list *rule,
 913                              named_ref *name)
 914 {
 915   self->kind = CODE_PROPS_RULE_ACTION;
 916   self->code = code;
 917   self->location = code_loc;
 918   self->is_value_used = false;
 919   self->rule = rule;
 920   self->named_ref = name;
 921 }
 922
 923 void
 924 code_props_translate_code (code_props *self)
 925 {
 926   switch (self->kind)
 927     {
 928       case CODE_PROPS_NONE:
 929         break;
 930       case CODE_PROPS_PLAIN:
 931         self->code = translate_action (self, INITIAL);
 932         break;
 933       case CODE_PROPS_SYMBOL_ACTION:
 934         self->code = translate_action (self, SC_SYMBOL_ACTION);
 935         break;
 936       case CODE_PROPS_RULE_ACTION:
 937         self->code = translate_action (self, SC_RULE_ACTION);
 938         break;
 939     }
 940 }
 941
 942 void
 943 code_scanner_last_string_free (void)
 944 {
 945   STRING_FREE;
 946 }
 947
 948 void
 949 code_scanner_free (void)
 950 {
 951   obstack_free (&obstack_for_string, 0);
 952   variant_table_free ();
 953
 954   /* Reclaim Flex's buffers.  */
 955   yylex_destroy ();
 956 }