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