src/scan-code.l

   1 /* Bison Action Scanner                             -*- C -*-
   2
   3    Copyright (C) 2006-2012 Free Software Foundation, Inc.
   4
   5    This file is part of Bison, the GNU Compiler Compiler.
   6
   7    This program is free software: you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation, either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 %option debug nodefault noinput nounput noyywrap never-interactive
  21 %option prefix="code_" outfile="lex.yy.c"
  22
  23 %{
  24 /* Work around a bug in flex 2.5.31.  See Debian bug 333231
  25    <http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=333231>.  */
  26 #undef code_wrap
  27 #define code_wrap() 1
  28
  29 #define FLEX_PREFIX(Id) code_ ## Id
  30 #include <src/flex-scanner.h>
  31
  32 #include <src/complain.h>
  33 #include <src/reader.h>
  34 #include <src/getargs.h>
  35 #include <src/muscle-tab.h>
  36 #include <src/scan-code.h>
  37 #include <src/symlist.h>
  38
  39 #include <c-ctype.h>
  40 #include <get-errno.h>
  41 #include <quote.h>
  42
  43 /* The current calling start condition: SC_RULE_ACTION or
  44    SC_SYMBOL_ACTION. */
  45 # define YY_DECL static char *code_lex (code_props *self, int sc_context)
  46 YY_DECL;
  47
  48 #define YY_USER_ACTION  location_compute (loc, &loc->end, yytext, yyleng);
  49
  50 static char *fetch_type_name (char *cp, char const **type_name,
  51                               location dollar_loc);
  52
  53 static void handle_action_dollar (symbol_list *rule, char *cp,
  54                                   location dollar_loc);
  55 static void handle_action_at (symbol_list *rule, char *cp, location at_loc);
  56
  57 /* A string to be pushed to obstack after dollar/at has been handled. */
  58 static char *ref_tail_fields;
  59
  60 static location the_location;
  61 static location *loc = &the_location;
  62
  63 /* A string representing the most recent translation.  */
  64 static char *last_string;
  65
  66 /* True if an untyped $$ or $n was seen.  */
  67 static bool untyped_var_seen;
  68
  69 %}
  70  /* C and C++ comments in code. */
  71 %x SC_COMMENT SC_LINE_COMMENT
  72  /* Strings and characters in code. */
  73 %x SC_STRING SC_CHARACTER
  74  /* Whether in a rule or symbol action.  Specifies the translation
  75     of $ and @.  */
  76 %x SC_RULE_ACTION SC_SYMBOL_ACTION
  77
  78
  79 /* POSIX says that a tag must be both an id and a C union member, but
  80    historically almost any character is allowed in a tag.  We disallow
  81    NUL and newline, as this simplifies our implementation.  */
  82 tag      [^\0\n>]+
  83
  84 /* Zero or more instances of backslash-newline.  Following GCC, allow
  85    white space between the backslash and the newline.  */
  86 splice   (\\[ \f\t\v]*\n)*
  87
  88 /* C style identifier. Must start with letter. Will be used for
  89    named symbol references. Shall be kept synchronized with
  90    scan-gram.l "letter" and "id". */
  91 letter    [.abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_]
  92 id        {letter}({letter}|[-0-9])*
  93 ref      -?[0-9]+|{id}|"["{id}"]"|"$"
  94
  95 %%
  96
  97 %{
  98   /* Nesting level of the current code in braces.  */
  99   int braces_level = 0;
 100
 101   /* Whether a semicolon is probably needed.
 102
 103      The heuristic is that a semicolon is not needed after '{', '}',
 104      ';', or a C preprocessor directive, and that whitespaces and
 105      comments do not affect this flag.  Note that '{' does not need a
 106      semicolon because of '{}'.  A semicolon may be needed before a
 107      cpp directive, but don't bother.
 108
 109      While it is maintained in several start-conditions (factoring
 110      opportunities), it is meaningful only for SC_RULE_ACTION. */
 111   bool need_semicolon = false;
 112
 113   /* Whether in a C preprocessor directive.  Don't use a start condition
 114      for this because, at the end of strings and comments, we still need
 115      to know whether we're in a directive.  */
 116   bool in_cpp = false;
 117
 118   /* This scanner is special: it is invoked only once, henceforth
 119      is expected to return only once.  This initialization is
 120      therefore done once per action to translate. */
 121   aver (sc_context == SC_SYMBOL_ACTION
 122         || sc_context == SC_RULE_ACTION
 123         || sc_context == INITIAL);
 124   BEGIN sc_context;
 125 %}
 126
 127   /*------------------------------------------------------------.
 128   | Scanning a C comment.  The initial '/ *' is already eaten.  |
 129   `------------------------------------------------------------*/
 130
 131 <SC_COMMENT>
 132 {
 133   "*"{splice}"/"  STRING_GROW; BEGIN sc_context;
 134 }
 135
 136
 137   /*--------------------------------------------------------------.
 138   | Scanning a line comment.  The initial '//' is already eaten.  |
 139   `--------------------------------------------------------------*/
 140
 141 <SC_LINE_COMMENT>
 142 {
 143   "\n"           STRING_GROW; BEGIN sc_context;
 144   {splice}       STRING_GROW;
 145 }
 146
 147
 148   /*--------------------------------------------.
 149   | Scanning user-code characters and strings.  |
 150   `--------------------------------------------*/
 151
 152 <SC_CHARACTER,SC_STRING>
 153 {
 154   {splice}|\\{splice}.  STRING_GROW;
 155 }
 156
 157 <SC_CHARACTER>
 158 {
 159   "'"           STRING_GROW; BEGIN sc_context;
 160 }
 161
 162 <SC_STRING>
 163 {
 164   "\""          STRING_GROW; BEGIN sc_context;
 165 }
 166
 167
 168 <SC_RULE_ACTION,SC_SYMBOL_ACTION>
 169 {
 170   "'" {
 171     STRING_GROW;
 172     BEGIN SC_CHARACTER;
 173     need_semicolon = true;
 174   }
 175   "\"" {
 176     STRING_GROW;
 177     BEGIN SC_STRING;
 178     need_semicolon = true;
 179   }
 180   "/"{splice}"*" {
 181     STRING_GROW;
 182     BEGIN SC_COMMENT;
 183   }
 184   "/"{splice}"/" {
 185     STRING_GROW;
 186     BEGIN SC_LINE_COMMENT;
 187   }
 188   [$@]  {
 189     complain (loc, Wother, _("stray '%s'"), yytext);
 190     obstack_escape (&obstack_for_string, yytext);
 191     need_semicolon = true;
 192   }
 193   [\[\]]  {
 194     obstack_escape (&obstack_for_string, yytext);
 195     need_semicolon = true;
 196   }
 197 }
 198
 199 <SC_RULE_ACTION>
 200 {
 201   "$"("<"{tag}">")?{ref}  {
 202     ref_tail_fields = NULL;
 203     handle_action_dollar (self->rule, yytext, *loc);
 204     if (ref_tail_fields)
 205       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 206     need_semicolon = true;
 207   }
 208   "@"{ref} {
 209     ref_tail_fields = NULL;
 210     handle_action_at (self->rule, yytext, *loc);
 211     if (ref_tail_fields)
 212       obstack_sgrow (&obstack_for_string, ref_tail_fields);
 213     need_semicolon = true;
 214   }
 215
 216   ";"  STRING_GROW;                 need_semicolon = false;
 217   "{"  STRING_GROW; ++braces_level; need_semicolon = false;
 218   "}"  {
 219     bool outer_brace = --braces_level == 0;
 220
 221     /* As an undocumented Bison extension, append ';' before the last
 222        brace in braced code, so that the user code can omit trailing
 223        ';'.  But do not append ';' if emulating Yacc, since Yacc does
 224        not append one.  This is deprecated since release 2.4.1.  */
 225     if (outer_brace && !yacc_flag && language_prio == default_prio
 226         && skeleton_prio == default_prio && need_semicolon && ! in_cpp)
 227       {
 228         unsigned int indent = 0;
 229         complain_indent (loc, Wdeprecated, &indent,
 230                          _("a ';' might be needed at the end of action code"));
 231         indent += SUB_INDENT;
 232         complain_indent (loc, Wdeprecated | silent, &indent,
 233                          _("future versions of Bison will not add the ';'"));
 234         obstack_1grow (&obstack_for_string, ';');
 235       }
 236
 237     STRING_GROW;
 238     need_semicolon = false;
 239   }
 240
 241   /* Preprocessing directives should only be recognized at the beginning
 242      of lines, allowing whitespace including comments, but in C/C++,
 243      '#' can only be the start of preprocessor directives or within
 244      '#define' directives anyway, so don't bother with begin of line.  */
 245   "#"       STRING_GROW; in_cpp = true;
 246
 247   {splice}  STRING_GROW;
 248   [\n\r]    STRING_GROW; if (in_cpp) in_cpp = need_semicolon = false;
 249   [ \t\f]   STRING_GROW;
 250   .         STRING_GROW; need_semicolon = true;
 251 }
 252
 253 <SC_SYMBOL_ACTION>
 254 {
 255   "$"("<"{tag}">")?"$" {
 256     const char *type_name = NULL;
 257     fetch_type_name (yytext + 1, &type_name, *loc)[-1] = 0;
 258     obstack_sgrow (&obstack_for_string, "]b4_dollar_dollar(");
 259     obstack_quote (&obstack_for_string, type_name);
 260     obstack_sgrow (&obstack_for_string, ")[");
 261     self->is_value_used = true;
 262   }
 263   "@$" {
 264     obstack_sgrow (&obstack_for_string, "]b4_at_dollar[");
 265     muscle_percent_define_ensure("locations", the_location, true);
 266   }
 267 }
 268
 269
 270 <*>
 271 {
 272   /* Escape M4 quoting characters in C code.  */
 273   [$@\[\]]    obstack_escape (&obstack_for_string, yytext);
 274
 275   /* By default, grow the string obstack with the input.  */
 276   .|\n        STRING_GROW;
 277
 278  /* End of processing. */
 279   <<EOF>>     STRING_FINISH; return last_string;
 280 }
 281
 282 %%
 283
 284 static inline bool
 285 is_dot_or_dash (char ch)
 286 {
 287   return ch == '.' || ch == '-';
 288 }
 289
 290 static inline bool
 291 contains_dot_or_dash (const char* p)
 292 {
 293   for (; *p; ++p)
 294     if (is_dot_or_dash (*p))
 295       return true;
 296   return false;
 297 }
 298
 299 /* Defines a variant of a symbolic name resolution. */
 300 typedef struct
 301 {
 302   /* Index in symbol list. */
 303   unsigned symbol_index;
 304
 305   /* Matched symbol id and loc. */
 306   uniqstr id;
 307   location loc;
 308
 309   /* Hiding named reference. */
 310   named_ref* hidden_by;
 311
 312   /* Error flags. May contain zero (no errors) or
 313      a combination of VARIANT_* values. */
 314   unsigned err;
 315 } variant;
 316
 317 /* Set when the variant refers to a symbol hidden
 318    by an explicit symbol reference. */
 319 #define VARIANT_HIDDEN (1 << 0)
 320
 321 /* Set when the variant refers to a symbol containing
 322    dots or dashes. Will require explicit bracketing. */
 323 #define VARIANT_BAD_BRACKETING (1 << 1)
 324
 325 /* Set when the variant refers to a symbol which is
 326    not visible from current midrule. */
 327 #define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
 328
 329 static variant *variant_table = NULL;
 330 static unsigned variant_table_size = 0;
 331 static unsigned variant_count = 0;
 332
 333 static variant *
 334 variant_table_grow (void)
 335 {
 336   ++variant_count;
 337   if (variant_count > variant_table_size)
 338     {
 339       while (variant_count > variant_table_size)
 340         variant_table_size = 2 * variant_table_size + 3;
 341       variant_table = xnrealloc (variant_table, variant_table_size,
 342                                  sizeof *variant_table);
 343     }
 344   return &variant_table[variant_count - 1];
 345 }
 346
 347 static void
 348 variant_table_free (void)
 349 {
 350   free (variant_table);
 351   variant_table = NULL;
 352   variant_table_size = variant_count = 0;
 353 }
 354
 355 static char *
 356 find_prefix_end (const char *prefix, char *begin, char *end)
 357 {
 358   char *ptr = begin;
 359
 360   for (; *prefix && ptr != end; ++prefix, ++ptr)
 361     if (*prefix != *ptr)
 362       return 0;
 363
 364   if (*prefix)
 365     return 0;
 366
 367   return ptr;
 368 }
 369
 370 static variant *
 371 variant_add (uniqstr id, location id_loc, unsigned symbol_index,
 372              char *cp, char *cp_end, bool explicit_bracketing)
 373 {
 374   char *prefix_end;
 375
 376   prefix_end = find_prefix_end (id, cp, cp_end);
 377   if (prefix_end &&
 378       (prefix_end == cp_end ||
 379        (!explicit_bracketing && is_dot_or_dash (*prefix_end))))
 380     {
 381       variant *r = variant_table_grow ();
 382       r->symbol_index = symbol_index;
 383       r->id = id;
 384       r->loc = id_loc;
 385       r->hidden_by = NULL;
 386       r->err = 0;
 387       return r;
 388     }
 389   else
 390     return NULL;
 391 }
 392
 393 static const char *
 394 get_at_spec(unsigned symbol_index)
 395 {
 396   static char at_buf[20];
 397   if (symbol_index == 0)
 398     strcpy (at_buf, "$$");
 399   else
 400     snprintf (at_buf, sizeof at_buf, "$%u", symbol_index);
 401   return at_buf;
 402 }
 403
 404 static void
 405 show_sub_message (warnings warning,
 406                   const char* cp, bool explicit_bracketing,
 407                   int midrule_rhs_index, char dollar_or_at,
 408                   unsigned indent, const variant *var)
 409 {
 410   const char *at_spec = get_at_spec (var->symbol_index);
 411
 412   if (var->err == 0)
 413     complain_indent (&var->loc, warning, &indent,
 414                      _("refers to: %c%s at %s"), dollar_or_at,
 415                      var->id, at_spec);
 416   else
 417     {
 418       static struct obstack msg_buf;
 419       const char *tail = explicit_bracketing ? "" : cp + strlen (var->id);
 420       const char *id = var->hidden_by ? var->hidden_by->id : var->id;
 421       location id_loc = var->hidden_by ? var->hidden_by->loc : var->loc;
 422
 423       /* Create the explanation message. */
 424       obstack_init (&msg_buf);
 425
 426       obstack_printf (&msg_buf, _("possibly meant: %c"), dollar_or_at);
 427       if (contains_dot_or_dash (id))
 428         obstack_printf (&msg_buf, "[%s]", id);
 429       else
 430         obstack_sgrow (&msg_buf, id);
 431       obstack_sgrow (&msg_buf, tail);
 432
 433       if (var->err & VARIANT_HIDDEN)
 434         {
 435           obstack_printf (&msg_buf, _(", hiding %c"), dollar_or_at);
 436           if (contains_dot_or_dash (var->id))
 437             obstack_printf (&msg_buf, "[%s]", var->id);
 438           else
 439             obstack_sgrow (&msg_buf, var->id);
 440           obstack_sgrow (&msg_buf, tail);
 441         }
 442
 443       obstack_printf (&msg_buf, _(" at %s"), at_spec);
 444
 445       if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
 446         obstack_printf (&msg_buf,
 447                         _(", cannot be accessed from mid-rule action at $%d"),
 448                         midrule_rhs_index);
 449
 450       complain_indent (&id_loc, warning, &indent, "%s",
 451                         obstack_finish0 (&msg_buf));
 452       obstack_free (&msg_buf, 0);
 453     }
 454 }
 455
 456 static void
 457 show_sub_messages (warnings warning,
 458                    const char* cp, bool explicit_bracketing,
 459                    int midrule_rhs_index, char dollar_or_at,
 460                    unsigned indent)
 461 {
 462   unsigned i;
 463
 464   for (i = 0; i < variant_count; ++i)
 465     show_sub_message (warning | silent,
 466                       cp, explicit_bracketing,
 467                       midrule_rhs_index, dollar_or_at,
 468                       indent, &variant_table[i]);
 469 }
 470
 471 /* Returned from "parse_ref" when the reference
 472    is inappropriate. */
 473 #define INVALID_REF (INT_MIN)
 474
 475 /* Returned from "parse_ref" when the reference
 476    points to LHS ($$) of the current rule or midrule. */
 477 #define LHS_REF (INT_MIN + 1)
 478
 479 /* Parse named or positional reference. In case of positional
 480    references, can return negative values for $-n "deep" stack
 481    accesses. */
 482 static long int
 483 parse_ref (char *cp, symbol_list *rule, int rule_length,
 484            int midrule_rhs_index, char *text, location text_loc,
 485            char dollar_or_at)
 486 {
 487   symbol_list *l;
 488   char *cp_end;
 489   bool explicit_bracketing;
 490   unsigned i;
 491   unsigned valid_variants = 0;
 492   unsigned valid_variant_index = 0;
 493
 494   if ('$' == *cp)
 495     return LHS_REF;
 496
 497   if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))
 498     {
 499       long int num = strtol (cp, &cp, 10);
 500       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
 501         return num;
 502       else
 503         {
 504           complain (&text_loc, complaint, _("integer out of range: %s"),
 505                     quote (text));
 506           return INVALID_REF;
 507         }
 508     }
 509
 510   if ('[' == *cp)
 511     {
 512       /* Ignore the brackets. */
 513       char *p;
 514       for (p = ++cp; *p != ']'; ++p)
 515         continue;
 516       cp_end = p;
 517
 518       explicit_bracketing = true;
 519     }
 520   else
 521     {
 522       /* Take all characters of the name. */
 523       char* p;
 524       for (p = cp; *p; ++p)
 525         if (is_dot_or_dash (*p))
 526           {
 527             ref_tail_fields = p;
 528             break;
 529           }
 530       for (p = cp; *p; ++p)
 531         continue;
 532       cp_end = p;
 533
 534       explicit_bracketing = false;
 535     }
 536
 537   /* Add all relevant variants. */
 538   {
 539     unsigned symbol_index;
 540     variant_count = 0;
 541     for (symbol_index = 0, l = rule; !symbol_list_null (l);
 542          ++symbol_index, l = l->next)
 543       {
 544         variant *var;
 545         if (l->content_type != SYMLIST_SYMBOL)
 546           continue;
 547
 548         var = variant_add (l->content.sym->tag, l->sym_loc,
 549                            symbol_index, cp, cp_end, explicit_bracketing);
 550         if (var && l->named_ref)
 551           var->hidden_by = l->named_ref;
 552
 553         if (l->named_ref)
 554           variant_add (l->named_ref->id, l->named_ref->loc,
 555                        symbol_index, cp, cp_end, explicit_bracketing);
 556       }
 557   }
 558
 559   /* Check errors. */
 560   for (i = 0; i < variant_count; ++i)
 561     {
 562       variant *var = &variant_table[i];
 563       unsigned symbol_index = var->symbol_index;
 564
 565       /* Check visibility from mid-rule actions. */
 566       if (midrule_rhs_index != 0
 567           && (symbol_index == 0 || midrule_rhs_index < symbol_index))
 568         var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
 569
 570       /* Check correct bracketing. */
 571       if (!explicit_bracketing && contains_dot_or_dash (var->id))
 572         var->err |= VARIANT_BAD_BRACKETING;
 573
 574       /* Check using of hidden symbols. */
 575       if (var->hidden_by)
 576         var->err |= VARIANT_HIDDEN;
 577
 578       if (!var->err)
 579         {
 580           valid_variant_index = i;
 581           ++valid_variants;
 582         }
 583     }
 584
 585   switch (valid_variants)
 586     {
 587     case 0:
 588       {
 589         unsigned len = (explicit_bracketing || !ref_tail_fields) ?
 590           cp_end - cp : ref_tail_fields - cp;
 591         unsigned indent = 0;
 592
 593         complain_indent (&text_loc, complaint, &indent,
 594                          _("invalid reference: %s"), quote (text));
 595         indent += SUB_INDENT;
 596         if (len == 0)
 597           {
 598             location sym_loc = text_loc;
 599             sym_loc.start.column += 1;
 600             sym_loc.end = sym_loc.start;
 601             complain_indent (&sym_loc, complaint, &indent,
 602                              _("syntax error after '%c', expecting integer, "
 603                                "letter, '_', '[', or '$'"),
 604                              dollar_or_at);
 605           }
 606         else if (midrule_rhs_index)
 607           complain_indent (&rule->location, complaint, &indent,
 608                            _("symbol not found in production before $%d: "
 609                              "%.*s"),
 610                            midrule_rhs_index, len, cp);
 611         else
 612           complain_indent (&rule->location, complaint, &indent,
 613                            _("symbol not found in production: %.*s"),
 614                            len, cp);
 615
 616         if (variant_count > 0)
 617           show_sub_messages (complaint,
 618                              cp, explicit_bracketing, midrule_rhs_index,
 619                              dollar_or_at, indent);
 620         return INVALID_REF;
 621       }
 622     case 1:
 623       {
 624         unsigned indent = 0;
 625         if (variant_count > 1)
 626           {
 627             complain_indent (&text_loc, Wother, &indent,
 628                              _("misleading reference: %s"), quote (text));
 629             show_sub_messages (Wother,
 630                                cp, explicit_bracketing, midrule_rhs_index,
 631                                dollar_or_at, indent + SUB_INDENT);
 632           }
 633         {
 634           unsigned symbol_index =
 635             variant_table[valid_variant_index].symbol_index;
 636           return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
 637         }
 638       }
 639     case 2:
 640     default:
 641       {
 642         unsigned indent = 0;
 643         complain_indent (&text_loc, complaint, &indent,
 644                          _("ambiguous reference: %s"), quote (text));
 645         show_sub_messages (complaint,
 646                            cp, explicit_bracketing, midrule_rhs_index,
 647                            dollar_or_at, indent + SUB_INDENT);
 648         return INVALID_REF;
 649       }
 650     }
 651
 652   /* Not reachable. */
 653   return INVALID_REF;
 654 }
 655
 656 /* Keeps track of the maximum number of semantic values to the left of
 657    a handle (those referenced by $0, $-1, etc.) are required by the
 658    semantic actions of this grammar. */
 659 int max_left_semantic_context = 0;
 660
 661
 662 /* If CP points to a typename (i.e., <.*?>), set TYPE_NAME to its
 663    beginning (i.e., after the opening "<", and return the pointer
 664    immediately after it.  */
 665
 666 static
 667 char *
 668 fetch_type_name (char *cp, char const **type_name,
 669                  location dollar_loc)
 670 {
 671   if (*cp == '<')
 672     {
 673       *type_name = ++cp;
 674       while (*cp != '>')
 675         ++cp;
 676
 677       /* The '>' symbol will be later replaced by '\0'. Original
 678          'text' is needed for error messages. */
 679       ++cp;
 680       if (untyped_var_seen)
 681         complain (&dollar_loc, complaint,
 682                   _("explicit type given in untyped grammar"));
 683       tag_seen = true;
 684     }
 685   return cp;
 686 }
 687
 688 /*------------------------------------------------------------------.
 689 | TEXT is pointing to a wannabee semantic value (i.e., a '$').      |
 690 |                                                                   |
 691 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 692 |                                                                   |
 693 | Output to OBSTACK_FOR_STRING a reference to this semantic value.  |
 694 `------------------------------------------------------------------*/
 695
 696 static void
 697 handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 698 {
 699   char const *type_name = NULL;
 700   char *cp = text + 1;
 701   symbol_list *effective_rule;
 702   int effective_rule_length;
 703   int n;
 704
 705   if (rule->midrule_parent_rule)
 706     {
 707       effective_rule = rule->midrule_parent_rule;
 708       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 709     }
 710   else
 711     {
 712       effective_rule = rule;
 713       effective_rule_length = symbol_list_length (rule->next);
 714     }
 715
 716   /* Get the type name if explicit. */
 717   cp = fetch_type_name (cp, &type_name, dollar_loc);
 718
 719   n = parse_ref (cp, effective_rule, effective_rule_length,
 720                  rule->midrule_parent_rhs_index, text, dollar_loc, '$');
 721
 722   /* End type_name. */
 723   if (type_name)
 724     cp[-1] = '\0';
 725
 726   switch (n)
 727     {
 728     case INVALID_REF:
 729       break;
 730
 731     case LHS_REF:
 732       if (!type_name)
 733         type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
 734
 735       if (!type_name)
 736         {
 737           if (union_seen | tag_seen)
 738             {
 739               if (rule->midrule_parent_rule)
 740                 complain (&dollar_loc, complaint,
 741                              _("$$ for the midrule at $%d of %s"
 742                                " has no declared type"),
 743                              rule->midrule_parent_rhs_index,
 744                              quote (effective_rule->content.sym->tag));
 745               else
 746                 complain (&dollar_loc, complaint,
 747                           _("$$ of %s has no declared type"),
 748                           quote (rule->content.sym->tag));
 749             }
 750           else
 751             untyped_var_seen = true;
 752         }
 753
 754       obstack_sgrow (&obstack_for_string, "]b4_lhs_value(");
 755       obstack_quote (&obstack_for_string, type_name);
 756       obstack_sgrow (&obstack_for_string, ")[");
 757       rule->action_props.is_value_used = true;
 758       break;
 759
 760     default:
 761       if (max_left_semantic_context < 1 - n)
 762         max_left_semantic_context = 1 - n;
 763       if (!type_name && 0 < n)
 764         type_name =
 765           symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
 766       if (!type_name)
 767         {
 768           if (union_seen | tag_seen)
 769             complain (&dollar_loc, complaint,
 770                       _("$%s of %s has no declared type"), cp,
 771                       quote (effective_rule->content.sym->tag));
 772           else
 773             untyped_var_seen = true;
 774         }
 775
 776       obstack_printf (&obstack_for_string,
 777                       "]b4_rhs_value(%d, %d, ", effective_rule_length, n);
 778       obstack_quote (&obstack_for_string, type_name);
 779       obstack_sgrow (&obstack_for_string, ")[");
 780       if (n > 0)
 781         symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
 782           true;
 783       break;
 784     }
 785 }
 786
 787
 788 /*------------------------------------------------------.
 789 | TEXT is a location token (i.e., a '@...').  Output to |
 790 | OBSTACK_FOR_STRING a reference to this location.      |
 791 `------------------------------------------------------*/
 792
 793 static void
 794 handle_action_at (symbol_list *rule, char *text, location at_loc)
 795 {
 796   char *cp = text + 1;
 797   symbol_list *effective_rule;
 798   int effective_rule_length;
 799   int n;
 800
 801   if (rule->midrule_parent_rule)
 802     {
 803       effective_rule = rule->midrule_parent_rule;
 804       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 805     }
 806   else
 807     {
 808       effective_rule = rule;
 809       effective_rule_length = symbol_list_length (rule->next);
 810     }
 811
 812   muscle_percent_define_ensure("locations", at_loc, true);
 813
 814   n = parse_ref (cp, effective_rule, effective_rule_length,
 815                        rule->midrule_parent_rhs_index, text, at_loc, '@');
 816   switch (n)
 817     {
 818     case INVALID_REF:
 819       break;
 820
 821     case LHS_REF:
 822       obstack_sgrow (&obstack_for_string, "]b4_lhs_location[");
 823       break;
 824
 825     default:
 826       obstack_printf (&obstack_for_string, "]b4_rhs_location(%d, %d)[",
 827                       effective_rule_length, n);
 828       break;
 829     }
 830 }
 831
 832
 833 /*-------------------------.
 834 | Initialize the scanner.  |
 835 `-------------------------*/
 836
 837 /* Translate the dollars and ats in \a self, in the context \a sc_context
 838    (SC_RULE_ACTION, SC_SYMBOL_ACTION, INITIAL).  */
 839
 840 static char const *
 841 translate_action (code_props *self, int sc_context)
 842 {
 843   char *res;
 844   static bool initialized = false;
 845   if (!initialized)
 846     {
 847       obstack_init (&obstack_for_string);
 848       yy_flex_debug = 0;
 849       initialized = true;
 850     }
 851
 852   loc->start = loc->end = self->location.start;
 853   yy_switch_to_buffer (yy_scan_string (self->code));
 854   res = code_lex (self, sc_context);
 855   yy_delete_buffer (YY_CURRENT_BUFFER);
 856
 857   return res;
 858 }
 859
 860 /*------------------------------------------------------------------------.
 861 | Implementation of the public interface as documented in "scan-code.h".  |
 862 `------------------------------------------------------------------------*/
 863
 864 void
 865 code_props_none_init (code_props *self)
 866 {
 867   *self = code_props_none;
 868 }
 869
 870 code_props code_props_none = CODE_PROPS_NONE_INIT;
 871
 872 void
 873 code_props_plain_init (code_props *self, char const *code,
 874                        location code_loc)
 875 {
 876   code_props_none_init (self);
 877   self->kind = CODE_PROPS_PLAIN;
 878   self->code = code;
 879   self->location = code_loc;
 880 }
 881
 882 void
 883 code_props_symbol_action_init (code_props *self, char const *code,
 884                                location code_loc)
 885 {
 886   code_props_none_init (self);
 887   self->kind = CODE_PROPS_SYMBOL_ACTION;
 888   self->code = code;
 889   self->location = code_loc;
 890 }
 891
 892 void
 893 code_props_rule_action_init (code_props *self, char const *code,
 894                              location code_loc, symbol_list *rule,
 895                              named_ref *name, bool is_predicate)
 896 {
 897   code_props_none_init (self);
 898   self->kind = CODE_PROPS_RULE_ACTION;
 899   self->code = code;
 900   self->location = code_loc;
 901   self->rule = rule;
 902   self->named_ref = name;
 903   self->is_predicate = is_predicate;
 904 }
 905
 906 void
 907 code_props_translate_code (code_props *self)
 908 {
 909   switch (self->kind)
 910     {
 911       case CODE_PROPS_NONE:
 912         break;
 913       case CODE_PROPS_PLAIN:
 914         self->code = translate_action (self, INITIAL);
 915         break;
 916       case CODE_PROPS_SYMBOL_ACTION:
 917         self->code = translate_action (self, SC_SYMBOL_ACTION);
 918         break;
 919       case CODE_PROPS_RULE_ACTION:
 920         self->code = translate_action (self, SC_RULE_ACTION);
 921         break;
 922     }
 923 }
 924
 925 void
 926 code_scanner_last_string_free (void)
 927 {
 928   STRING_FREE;
 929 }
 930
 931 void
 932 code_scanner_free (void)
 933 {
 934   obstack_free (&obstack_for_string, 0);
 935   variant_table_free ();
 936
 937   /* Reclaim Flex's buffers.  */
 938   yylex_destroy ();
 939 }