src/scan-code.l

   1 /* Bison Action Scanner                             -*- C -*-
   2
   3    Copyright (C) 2006, 2007, 2008-2009 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   .         STRING_GROW; need_semicolon = true;
 249 }
 250
 251 <SC_SYMBOL_ACTION>
 252 {
 253   "$$" {
 254     obstack_sgrow (&obstack_for_string, "]b4_dollar_dollar[");
 255     self->is_value_used = true;
 256   }
 257   "@$" {
 258     obstack_sgrow (&obstack_for_string, "]b4_at_dollar[");
 259     locations_flag = true;
 260   }
 261 }
 262
 263
 264   /*-----------------------------------------.
 265   | Escape M4 quoting characters in C code.  |
 266   `-----------------------------------------*/
 267
 268 <*>
 269 {
 270   \$    obstack_sgrow (&obstack_for_string, "$][");
 271   \@    obstack_sgrow (&obstack_for_string, "@@");
 272   \[    obstack_sgrow (&obstack_for_string, "@{");
 273   \]    obstack_sgrow (&obstack_for_string, "@}");
 274 }
 275
 276   /*-----------------------------------------------------.
 277   | By default, grow the string obstack with the input.  |
 278   `-----------------------------------------------------*/
 279
 280 <*>.|\n STRING_GROW;
 281
 282  /* End of processing. */
 283 <*><<EOF>>       {
 284                    STRING_FINISH;
 285                    return last_string;
 286                  }
 287
 288 %%
 289
 290 static inline bool
 291 is_dot_or_dash (char ch)
 292 {
 293   return ch == '.' || ch == '-';
 294 }
 295
 296 static inline bool
 297 contains_dot_or_dash (const char* p)
 298 {
 299   for (; *p; ++p)
 300     if (is_dot_or_dash (*p))
 301       return true;
 302   return false;
 303 }
 304
 305 /* Defines a variant of a symbolic name resolution. */
 306 typedef struct
 307 {
 308   /* Index in symbol list. */
 309   unsigned symbol_index;
 310
 311   /* Matched symbol id and loc. */
 312   uniqstr id;
 313   location loc;
 314
 315   /* Hiding named reference. */
 316   named_ref* hidden_by;
 317
 318   /* Error flags. May contain zero (no errors) or
 319      a combination of VARIANT_* values. */
 320   unsigned err;
 321 } variant;
 322
 323 /* Set when the variant refers to a symbol hidden
 324    by an explicit symbol reference. */
 325 #define VARIANT_HIDDEN (1 << 0)
 326
 327 /* Set when the variant refers to a symbol containing
 328    dots or dashes. Will require explicit bracketing. */
 329 #define VARIANT_BAD_BRACKETING (1 << 1)
 330
 331 /* Set when the variant refers to a symbol which is
 332    not visible from current midrule. */
 333 #define VARIANT_NOT_VISIBLE_FROM_MIDRULE (1 << 2)
 334
 335 static variant *variant_table = 0;
 336 static unsigned variant_table_size = 0;
 337 static unsigned variant_count = 0;
 338
 339 static variant *
 340 variant_table_grow (void)
 341 {
 342   ++variant_count;
 343   if (variant_count > variant_table_size)
 344     {
 345       while (variant_count > variant_table_size)
 346         variant_table_size = 2 * variant_table_size + 3;
 347       variant_table = xnrealloc (variant_table, variant_table_size,
 348                                  sizeof *variant_table);
 349     }
 350   return &variant_table[variant_count - 1];
 351 }
 352
 353 static void
 354 variant_table_free (void)
 355 {
 356   free (variant_table);
 357   variant_table = 0;
 358   variant_table_size = variant_count = 0;
 359 }
 360
 361 static char *
 362 find_prefix_end (const char *prefix, char *begin, char *end)
 363 {
 364   char *ptr = begin;
 365
 366   for (; *prefix && ptr != end; ++prefix, ++ptr)
 367     if (*prefix != *ptr)
 368       return 0;
 369
 370   if (*prefix)
 371     return 0;
 372
 373   return ptr;
 374 }
 375
 376 static variant *
 377 variant_add (uniqstr id, location id_loc, unsigned symbol_index,
 378              char *cp, char *cp_end, bool explicit_bracketing)
 379 {
 380   char *prefix_end;
 381
 382   prefix_end = find_prefix_end (id, cp, cp_end);
 383   if (prefix_end &&
 384       (prefix_end == cp_end ||
 385        (!explicit_bracketing && is_dot_or_dash (*prefix_end))))
 386     {
 387       variant *r = variant_table_grow ();
 388       r->symbol_index = symbol_index;
 389       r->id = id;
 390       r->loc = id_loc;
 391       r->hidden_by = NULL;
 392       r->err = 0;
 393       return r;
 394     }
 395   else
 396     return NULL;
 397 }
 398
 399 static const char *
 400 get_at_spec(unsigned symbol_index)
 401 {
 402   static char at_buf[20];
 403   if (symbol_index == 0)
 404     strcpy (at_buf, "$$");
 405   else
 406     snprintf (at_buf, sizeof at_buf, "$%u", symbol_index);
 407   return at_buf;
 408 }
 409
 410 static void
 411 show_sub_messages (const char* cp, bool explicit_bracketing,
 412                    int midrule_rhs_index, char dollar_or_at,
 413                    bool is_warning, unsigned indent)
 414 {
 415   unsigned i;
 416
 417   for (i = 0; i < variant_count; ++i)
 418     {
 419       const variant *var = &variant_table[i];
 420       const char *at_spec = get_at_spec (var->symbol_index);
 421
 422       if (var->err == 0)
 423         {
 424           if (is_warning)
 425             warn_at_indent (var->loc, &indent, _("refers to: %c%s at %s"),
 426                             dollar_or_at, var->id, at_spec);
 427           else
 428             complain_at_indent (var->loc, &indent, _("refers to: %c%s at %s"),
 429                                 dollar_or_at, var->id, at_spec);
 430         }
 431       else
 432         {
 433           static struct obstack msg_buf;
 434           const char *tail = explicit_bracketing ? "" :
 435             cp + strlen (var->id);
 436           const char *id = var->hidden_by ? var->hidden_by->id :
 437             var->id;
 438           location id_loc = var->hidden_by ? var->hidden_by->loc :
 439             var->loc;
 440
 441           /* Create the explanation message. */
 442           obstack_init (&msg_buf);
 443
 444           obstack_fgrow1 (&msg_buf, _("possibly meant: %c"), dollar_or_at);
 445           if (contains_dot_or_dash (id))
 446             obstack_fgrow1 (&msg_buf, "[%s]", id);
 447           else
 448             obstack_sgrow (&msg_buf, id);
 449           obstack_sgrow (&msg_buf, tail);
 450
 451           if (var->err & VARIANT_HIDDEN)
 452             {
 453               obstack_fgrow1 (&msg_buf, _(", hiding %c"), dollar_or_at);
 454               if (contains_dot_or_dash (var->id))
 455                 obstack_fgrow1 (&msg_buf, "[%s]", var->id);
 456               else
 457                 obstack_sgrow (&msg_buf, var->id);
 458               obstack_sgrow (&msg_buf, tail);
 459             }
 460
 461           obstack_fgrow1 (&msg_buf, _(" at %s"), at_spec);
 462
 463           if (var->err & VARIANT_NOT_VISIBLE_FROM_MIDRULE)
 464             {
 465               const char *format =
 466                 _(", cannot be accessed from mid-rule action at $%d");
 467               obstack_fgrow1 (&msg_buf, format, midrule_rhs_index);
 468             }
 469
 470           obstack_1grow (&msg_buf, '\0');
 471           if (is_warning)
 472             warn_at_indent (id_loc, &indent, "%s",
 473                             (char *) obstack_finish (&msg_buf));
 474           else
 475             complain_at_indent (id_loc, &indent, "%s",
 476                                 (char *) obstack_finish (&msg_buf));
 477           obstack_free (&msg_buf, 0);
 478         }
 479     }
 480 }
 481
 482 /* Returned from "parse_ref" when the reference
 483    is inappropriate. */
 484 #define INVALID_REF (INT_MIN)
 485
 486 /* Returned from "parse_ref" when the reference
 487    points to LHS ($$) of the current rule or midrule. */
 488 #define LHS_REF (INT_MIN + 1)
 489
 490 /* Sub-messages indent. */
 491 #define SUB_INDENT (4)
 492
 493 /* Parse named or positional reference. In case of positional
 494    references, can return negative values for $-n "deep" stack
 495    accesses. */
 496 static long int
 497 parse_ref (char *cp, symbol_list *rule, int rule_length,
 498            int midrule_rhs_index, char *text, location text_loc,
 499            char dollar_or_at)
 500 {
 501   symbol_list *l;
 502   char *cp_end;
 503   bool explicit_bracketing;
 504   unsigned i;
 505   unsigned valid_variants = 0;
 506   unsigned valid_variant_index = 0;
 507
 508   if ('$' == *cp)
 509     return LHS_REF;
 510
 511   if (c_isdigit (*cp) || (*cp == '-' && c_isdigit (* (cp + 1))))
 512     {
 513       long int num = strtol (cp, &cp, 10);
 514       if (1 - INT_MAX + rule_length <= num && num <= rule_length)
 515         return num;
 516       else
 517         {
 518           complain_at (text_loc, _("integer out of range: %s"),
 519                        quote (text));
 520           return INVALID_REF;
 521         }
 522     }
 523
 524   if ('[' == *cp)
 525     {
 526       /* Ignore the brackets. */
 527       char *p;
 528       for (p = ++cp; *p != ']'; ++p)
 529         continue;
 530       cp_end = p;
 531
 532       explicit_bracketing = true;
 533     }
 534   else
 535     {
 536       /* Take all characters of the name. */
 537       char* p;
 538       for (p = cp; *p; ++p)
 539         if (is_dot_or_dash (*p))
 540           {
 541             ref_tail_fields = p;
 542             break;
 543           }
 544       for (p = cp; *p; ++p)
 545         continue;
 546       cp_end = p;
 547
 548       explicit_bracketing = false;
 549     }
 550
 551   /* Add all relevant variants. */
 552   {
 553     unsigned symbol_index;
 554     variant_count = 0;
 555     for (symbol_index = 0, l = rule; !symbol_list_null (l);
 556          ++symbol_index, l = l->next)
 557       {
 558         variant *var;
 559         if (l->content_type != SYMLIST_SYMBOL)
 560           continue;
 561
 562         var = variant_add (l->content.sym->tag, l->sym_loc,
 563                            symbol_index, cp, cp_end, explicit_bracketing);
 564         if (var && l->named_ref)
 565           var->hidden_by = l->named_ref;
 566
 567         if (l->named_ref)
 568           variant_add (l->named_ref->id, l->named_ref->loc,
 569                        symbol_index, cp, cp_end, explicit_bracketing);
 570       }
 571   }
 572
 573   /* Check errors. */
 574   for (i = 0; i < variant_count; ++i)
 575     {
 576       variant *var = &variant_table[i];
 577       unsigned symbol_index = var->symbol_index;
 578
 579       /* Check visibility from mid-rule actions. */
 580       if (midrule_rhs_index != 0
 581           && (symbol_index == 0 || midrule_rhs_index < symbol_index))
 582         var->err |= VARIANT_NOT_VISIBLE_FROM_MIDRULE;
 583
 584       /* Check correct bracketing. */
 585       if (!explicit_bracketing && contains_dot_or_dash (var->id))
 586         var->err |= VARIANT_BAD_BRACKETING;
 587
 588       /* Check using of hidden symbols. */
 589       if (var->hidden_by)
 590         var->err |= VARIANT_HIDDEN;
 591
 592       if (!var->err)
 593         {
 594           valid_variant_index = i;
 595           ++valid_variants;
 596         }
 597     }
 598
 599   switch (valid_variants)
 600     {
 601     case 0:
 602       {
 603         unsigned len = (explicit_bracketing || !ref_tail_fields) ?
 604           cp_end - cp : ref_tail_fields - cp;
 605         unsigned indent = 0;
 606
 607         complain_at_indent (text_loc, &indent, _("invalid reference: %s"),
 608                             quote (text));
 609         indent += SUB_INDENT;
 610         if (midrule_rhs_index)
 611           {
 612             const char *format =
 613               _("symbol not found in production before $%d: %.*s");
 614             complain_at_indent (rule->location, &indent, format,
 615                                 midrule_rhs_index, len, cp);
 616           }
 617         else
 618           {
 619             const char *format =
 620               _("symbol not found in production: %.*s");
 621             complain_at_indent (rule->location, &indent, format,
 622                                 len, cp);
 623           }
 624
 625         if (variant_count > 0)
 626           show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 627                              dollar_or_at, false, indent);
 628         return INVALID_REF;
 629       }
 630     case 1:
 631       {
 632         unsigned indent = 0;
 633         if (variant_count > 1)
 634           {
 635             warn_at_indent (text_loc, &indent, _("misleading reference: %s"),
 636                             quote (text));
 637             show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 638                                dollar_or_at, true, indent + SUB_INDENT);
 639           }
 640         {
 641           unsigned symbol_index =
 642             variant_table[valid_variant_index].symbol_index;
 643           return (symbol_index == midrule_rhs_index) ? LHS_REF : symbol_index;
 644         }
 645       }
 646     case 2:
 647     default:
 648       {
 649         unsigned indent = 0;
 650         complain_at_indent (text_loc, &indent, _("ambiguous reference: %s"),
 651                             quote (text));
 652         show_sub_messages (cp, explicit_bracketing, midrule_rhs_index,
 653                            dollar_or_at, false, indent + SUB_INDENT);
 654         return INVALID_REF;
 655       }
 656     }
 657
 658   /* Not reachable. */
 659   return INVALID_REF;
 660 }
 661
 662 /* Keeps track of the maximum number of semantic values to the left of
 663    a handle (those referenced by $0, $-1, etc.) are required by the
 664    semantic actions of this grammar. */
 665 int max_left_semantic_context = 0;
 666
 667
 668 /*------------------------------------------------------------------.
 669 | TEXT is pointing to a wannabee semantic value (i.e., a `$').      |
 670 |                                                                   |
 671 | Possible inputs: $[<TYPENAME>]($|integer)                         |
 672 |                                                                   |
 673 | Output to OBSTACK_FOR_STRING a reference to this semantic value.  |
 674 `------------------------------------------------------------------*/
 675
 676 static void
 677 handle_action_dollar (symbol_list *rule, char *text, location dollar_loc)
 678 {
 679   char const *type_name = NULL;
 680   char *cp = text + 1;
 681   char *gt_ptr = 0;
 682   symbol_list *effective_rule;
 683   int effective_rule_length;
 684   int n;
 685
 686   if (rule->midrule_parent_rule)
 687     {
 688       effective_rule = rule->midrule_parent_rule;
 689       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 690     }
 691   else
 692     {
 693       effective_rule = rule;
 694       effective_rule_length = symbol_list_length (rule->next);
 695     }
 696
 697   /* Get the type name if explicit. */
 698   if (*cp == '<')
 699     {
 700       type_name = ++cp;
 701       while (*cp != '>')
 702         ++cp;
 703
 704       /* The '>' symbol will be later replaced by '\0'. Original
 705          'text' is needed for error messages. */
 706       gt_ptr = cp;
 707       ++cp;
 708       if (untyped_var_seen)
 709         complain_at (dollar_loc, _("explicit type given in untyped grammar"));
 710       tag_seen = true;
 711     }
 712
 713   n = parse_ref (cp, effective_rule, effective_rule_length,
 714                  rule->midrule_parent_rhs_index, text, dollar_loc, '$');
 715
 716   if (gt_ptr)
 717     *gt_ptr = '\0';
 718
 719   switch (n)
 720     {
 721     case INVALID_REF:
 722       break;
 723
 724     case LHS_REF:
 725       if (!type_name)
 726         type_name = symbol_list_n_type_name_get (rule, dollar_loc, 0);
 727
 728       if (!type_name)
 729         {
 730           if (union_seen | tag_seen)
 731             {
 732               if (rule->midrule_parent_rule)
 733                 complain_at (dollar_loc,
 734                              _("$$ for the midrule at $%d of `%s'"
 735                                " has no declared type"),
 736                              rule->midrule_parent_rhs_index,
 737                              effective_rule->content.sym->tag);
 738               else
 739                 complain_at (dollar_loc, _("$$ of `%s' has no declared type"),
 740                              rule->content.sym->tag);
 741             }
 742           else
 743             untyped_var_seen = true;
 744           type_name = "";
 745         }
 746
 747       obstack_fgrow1 (&obstack_for_string,
 748                       "]b4_lhs_value([%s])[", type_name);
 749       rule->action_props.is_value_used = true;
 750       break;
 751
 752     default:
 753       if (max_left_semantic_context < 1 - n)
 754         max_left_semantic_context = 1 - n;
 755       if (!type_name && 0 < n)
 756         type_name =
 757           symbol_list_n_type_name_get (effective_rule, dollar_loc, n);
 758       if (!type_name)
 759         {
 760           if (union_seen | tag_seen)
 761             complain_at (dollar_loc, _("$%s of `%s' has no declared type"),
 762                          cp, effective_rule->content.sym->tag);
 763           else
 764             untyped_var_seen = true;
 765           type_name = "";
 766         }
 767
 768       obstack_fgrow3 (&obstack_for_string,
 769                       "]b4_rhs_value(%d, %d, [%s])[",
 770                       effective_rule_length, n, type_name);
 771       if (n > 0)
 772         symbol_list_n_get (effective_rule, n)->action_props.is_value_used =
 773           true;
 774       break;
 775     }
 776 }
 777
 778
 779 /*------------------------------------------------------.
 780 | TEXT is a location token (i.e., a `@...').  Output to |
 781 | OBSTACK_FOR_STRING a reference to this location.      |
 782 `------------------------------------------------------*/
 783
 784 static void
 785 handle_action_at (symbol_list *rule, char *text, location at_loc)
 786 {
 787   char *cp = text + 1;
 788   symbol_list *effective_rule;
 789   int effective_rule_length;
 790   int n;
 791
 792   if (rule->midrule_parent_rule)
 793     {
 794       effective_rule = rule->midrule_parent_rule;
 795       effective_rule_length = rule->midrule_parent_rhs_index - 1;
 796     }
 797   else
 798     {
 799       effective_rule = rule;
 800       effective_rule_length = symbol_list_length (rule->next);
 801     }
 802
 803   locations_flag = true;
 804
 805   n = parse_ref (cp, effective_rule, effective_rule_length,
 806                        rule->midrule_parent_rhs_index, text, at_loc, '@');
 807   switch (n)
 808     {
 809     case INVALID_REF:
 810       break;
 811
 812     case LHS_REF:
 813       obstack_sgrow (&obstack_for_string, "]b4_lhs_location[");
 814       break;
 815
 816     default:
 817       obstack_fgrow2 (&obstack_for_string, "]b4_rhs_location(%d, %d)[",
 818                       effective_rule_length, n);
 819       break;
 820     }
 821 }
 822
 823
 824 /*-------------------------.
 825 | Initialize the scanner.  |
 826 `-------------------------*/
 827
 828 /* Translate the dollars and ats in \a self, in the context \a sc_context
 829    (SC_RULE_ACTION, SC_SYMBOL_ACTION, INITIAL).  */
 830
 831 static char const *
 832 translate_action (code_props *self, int sc_context)
 833 {
 834   char *res;
 835   static bool initialized = false;
 836   if (!initialized)
 837     {
 838       obstack_init (&obstack_for_string);
 839       yy_flex_debug = 0;
 840       initialized = true;
 841     }
 842
 843   loc->start = loc->end = self->location.start;
 844   yy_switch_to_buffer (yy_scan_string (self->code));
 845   res = code_lex (self, sc_context);
 846   yy_delete_buffer (YY_CURRENT_BUFFER);
 847
 848   return res;
 849 }
 850
 851 /*------------------------------------------------------------------------.
 852 | Implementation of the public interface as documented in "scan-code.h".  |
 853 `------------------------------------------------------------------------*/
 854
 855 void
 856 code_props_none_init (code_props *self)
 857 {
 858   *self = code_props_none;
 859 }
 860
 861 code_props const code_props_none = CODE_PROPS_NONE_INIT;
 862
 863 void
 864 code_props_plain_init (code_props *self, char const *code,
 865                        location code_loc)
 866 {
 867   self->kind = CODE_PROPS_PLAIN;
 868   self->code = code;
 869   self->location = code_loc;
 870   self->is_value_used = false;
 871   self->rule = NULL;
 872   self->named_ref = NULL;
 873 }
 874
 875 void
 876 code_props_symbol_action_init (code_props *self, char const *code,
 877                                location code_loc)
 878 {
 879   self->kind = CODE_PROPS_SYMBOL_ACTION;
 880   self->code = code;
 881   self->location = code_loc;
 882   self->is_value_used = false;
 883   self->rule = NULL;
 884   self->named_ref = NULL;
 885 }
 886
 887 void
 888 code_props_rule_action_init (code_props *self, char const *code,
 889                              location code_loc, symbol_list *rule,
 890                              named_ref *name)
 891 {
 892   self->kind = CODE_PROPS_RULE_ACTION;
 893   self->code = code;
 894   self->location = code_loc;
 895   self->is_value_used = false;
 896   self->rule = rule;
 897   self->named_ref = name;
 898 }
 899
 900 void
 901 code_props_translate_code (code_props *self)
 902 {
 903   switch (self->kind)
 904     {
 905       case CODE_PROPS_NONE:
 906         break;
 907       case CODE_PROPS_PLAIN:
 908         self->code = translate_action (self, INITIAL);
 909         break;
 910       case CODE_PROPS_SYMBOL_ACTION:
 911         self->code = translate_action (self, SC_SYMBOL_ACTION);
 912         break;
 913       case CODE_PROPS_RULE_ACTION:
 914         self->code = translate_action (self, SC_RULE_ACTION);
 915         break;
 916     }
 917 }
 918
 919 void
 920 code_scanner_last_string_free (void)
 921 {
 922   STRING_FREE;
 923 }
 924
 925 void
 926 code_scanner_free (void)
 927 {
 928   obstack_free (&obstack_for_string, 0);
 929   variant_table_free ();
 930
 931   /* Reclaim Flex's buffers.  */
 932   yylex_destroy ();
 933 }