src/state.c

   1 /* Type definitions for nondeterministic finite state machine for bison,
   2    Copyright (C) 2001, 2002  Free Software Foundation, Inc.
   3
   4    This file is part of Bison, the GNU Compiler Compiler.
   5
   6    Bison is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    Bison is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with Bison; see the file COPYING.  If not, write to
  18    the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  19    Boston, MA 02111-1307, USA.  */
  20
  21
  22 #include "system.h"
  23 #include "hash.h"
  24 #include "complain.h"
  25 #include "gram.h"
  26 #include "state.h"
  27
  28
  29                         /*-------------------.
  30                         | Shifts and Gotos.  |
  31                         `-------------------*/
  32
  33
  34 /*---------------------------------------.
  35 | Create a new array of N shifts/gotos.  |
  36 `---------------------------------------*/
  37
  38 #define TRANSITIONS_ALLOC(Num)                                          \
  39   (transitions_t *) xcalloc ((sizeof (transitions_t)                    \
  40                                   + (Num - 1) * sizeof (state_t *)), 1)
  41
  42 static transitions_t *
  43 transitions_new (int num, state_t **the_states)
  44 {
  45   transitions_t *res = TRANSITIONS_ALLOC (num);
  46   res->num = num;
  47   memcpy (res->states, the_states, num * sizeof (the_states[0]));
  48   return res;
  49 }
  50
  51
  52 /*-------------------------------------------------------------------.
  53 | Return the state such these TRANSITIONS contain a shift/goto to it |
  54 | on SYMBOL.  Aborts if none found.                                  |
  55 `-------------------------------------------------------------------*/
  56
  57 state_t *
  58 transitions_to (transitions_t *shifts, symbol_number_t s)
  59 {
  60   int j;
  61   for (j = 0; j < shifts->num; j++)
  62     if (TRANSITION_SYMBOL (shifts, j) == s)
  63       return shifts->states[j];
  64   abort ();
  65 }
  66
  67
  68                         /*--------------------.
  69                         | Error transitions.  |
  70                         `--------------------*/
  71
  72
  73 /*-------------------------------.
  74 | Create a new array of N errs.  |
  75 `-------------------------------*/
  76
  77 #define ERRS_ALLOC(Nerrs)                               \
  78   (errs_t *) xcalloc ((sizeof (errs_t)                  \
  79                       + (Nerrs - 1) * sizeof (symbol_t *)), 1)
  80
  81
  82 errs_t *
  83 errs_new (int num, symbol_t **tokens)
  84 {
  85   errs_t *res = ERRS_ALLOC (num);
  86   res->num = num;
  87   memcpy (res->symbols, tokens, num * sizeof (tokens[0]));
  88   return res;
  89 }
  90
  91
  92
  93
  94                         /*-------------.
  95                         | Reductions.  |
  96                         `-------------*/
  97
  98
  99 /*-------------------------------------.
 100 | Create a new array of N reductions.  |
 101 `-------------------------------------*/
 102
 103 #define REDUCTIONS_ALLOC(Nreductions)                          \
 104   (reductions_t *) xcalloc ((sizeof (reductions_t)             \
 105                             + (Nreductions - 1) * sizeof (rule_t *)), 1)
 106
 107 static reductions_t *
 108 reductions_new (int num, rule_t **reductions)
 109 {
 110   reductions_t *res = REDUCTIONS_ALLOC (num);
 111   res->num = num;
 112   memcpy (res->rules, reductions, num * sizeof (reductions[0]));
 113   res->lookaheads = NULL;
 114   return res;
 115 }
 116
 117
 118
 119                         /*---------.
 120                         | States.  |
 121                         `---------*/
 122
 123
 124 state_number_t nstates = 0;
 125 /* FINAL_STATE is properly set by new_state when it recognizes its
 126    accessing symbol: $end.  */
 127 state_t *final_state = NULL;
 128
 129 #define STATE_ALLOC(Nitems)                                             \
 130   (state_t *) xcalloc ((sizeof (state_t)                                \
 131                         + (Nitems - 1) * sizeof (item_number_t)), 1)
 132
 133 /*------------------------------------------------------------------.
 134 | Create a new state with ACCESSING_SYMBOL, for those items.  Store |
 135 | it in the state hash table.                                       |
 136 `------------------------------------------------------------------*/
 137
 138 state_t *
 139 state_new (symbol_number_t accessing_symbol,
 140            size_t core_size, item_number_t *core)
 141 {
 142   state_t *res;
 143
 144   assert (nstates < STATE_NUMBER_MAX);
 145
 146   res = STATE_ALLOC (core_size);
 147   res->accessing_symbol = accessing_symbol;
 148   res->number = nstates;
 149   ++nstates;
 150   res->solved_conflicts = NULL;
 151
 152   res->nitems = core_size;
 153   memcpy (res->items, core, core_size * sizeof (core[0]));
 154
 155   state_hash_insert (res);
 156
 157   return res;
 158 }
 159
 160
 161 /*-------------.
 162 | Free STATE.  |
 163 `-------------*/
 164
 165 static void
 166 state_free (state_t *state)
 167 {
 168   free (state->transitions);
 169   free (state->reductions);
 170   free (state->errs);
 171   free (state);
 172 }
 173
 174
 175 /*-------------------------------.
 176 | Set the transitions of STATE.  |
 177 `-------------------------------*/
 178
 179 void
 180 state_transitions_set (state_t *state, int num, state_t **transitions)
 181 {
 182   assert (!state->transitions);
 183   state->transitions = transitions_new (num, transitions);
 184 }
 185
 186
 187 /*------------------------------.
 188 | Set the reductions of STATE.  |
 189 `------------------------------*/
 190
 191 void
 192 state_reductions_set (state_t *state, int num, rule_t **reductions)
 193 {
 194   assert (!state->reductions);
 195   state->reductions = reductions_new (num, reductions);
 196 }
 197
 198
 199 int
 200 state_reduction_find (state_t *state, rule_t *rule)
 201 {
 202   int i;
 203   reductions_t *reds = state->reductions;
 204   for (i = 0; i < reds->num; ++i)
 205     if (reds->rules[i] == rule)
 206       return i;
 207   return -1;
 208 }
 209
 210
 211 /*------------------------.
 212 | Set the errs of STATE.  |
 213 `------------------------*/
 214
 215 void
 216 state_errs_set (state_t *state, int num, symbol_t **tokens)
 217 {
 218   assert (!state->errs);
 219   state->errs = errs_new (num, tokens);
 220 }
 221
 222
 223
 224 /*--------------------------------------------------------------.
 225 | Print on OUT all the lookaheads such that this STATE wants to |
 226 | reduce this RULE.                                             |
 227 `--------------------------------------------------------------*/
 228
 229 void
 230 state_rule_lookaheads_print (state_t *state, rule_t *rule, FILE *out)
 231 {
 232   /* Find the reduction we are handling.  */
 233   reductions_t *reds = state->reductions;
 234   int red = state_reduction_find (state, rule);
 235
 236   /* Print them if there are.  */
 237   if (reds->lookaheads && red != -1)
 238     {
 239       bitset_iterator biter;
 240       int k;
 241       int not_first = 0;
 242       fprintf (out, "  [");
 243       BITSET_FOR_EACH (biter, reds->lookaheads[red], k, 0)
 244         fprintf (out, "%s%s",
 245                  not_first++ ? ", " : "",
 246                  symbols[k]->tag);
 247       fprintf (out, "]");
 248     }
 249 }
 250
 251
 252 /*----------------------.
 253 | A state hash table.  |
 254 `----------------------*/
 255
 256 /* Initial capacity of states hash table.  */
 257 #define HT_INITIAL_CAPACITY 257
 258
 259 static struct hash_table *state_table = NULL;
 260
 261 /* Two states are equal if they have the same core items.  */
 262 static bool
 263 state_compare (const state_t *s1, const state_t *s2)
 264 {
 265   int i;
 266
 267   if (s1->nitems != s2->nitems)
 268     return false;
 269
 270   for (i = 0; i < s1->nitems; ++i)
 271     if (s1->items[i] != s2->items[i])
 272       return false;
 273
 274   return true;
 275 }
 276
 277 static unsigned int
 278 state_hash (const state_t *state, unsigned int tablesize)
 279 {
 280   /* Add up the state's item numbers to get a hash key.  */
 281   int key = 0;
 282   int i;
 283   for (i = 0; i < state->nitems; ++i)
 284     key += state->items[i];
 285   return key % tablesize;
 286 }
 287
 288
 289 /*-------------------------------.
 290 | Create the states hash table.  |
 291 `-------------------------------*/
 292
 293 void
 294 state_hash_new (void)
 295 {
 296   state_table = hash_initialize (HT_INITIAL_CAPACITY,
 297                                  NULL,
 298                                  (Hash_hasher) state_hash,
 299                                  (Hash_comparator) state_compare,
 300                                  (Hash_data_freer) NULL);
 301 }
 302
 303
 304 /*---------------------------------------------.
 305 | Free the states hash table, not the states.  |
 306 `---------------------------------------------*/
 307
 308 void
 309 state_hash_free (void)
 310 {
 311   hash_free (state_table);
 312 }
 313
 314
 315 /*---------------------------------------.
 316 | Insert STATE in the state hash table.  |
 317 `---------------------------------------*/
 318
 319 void
 320 state_hash_insert (state_t *state)
 321 {
 322   hash_insert (state_table, state);
 323 }
 324
 325
 326 /*------------------------------------------------------------------.
 327 | Find the state associated to the CORE, and return it.  If it does |
 328 | not exist yet, return NULL.                                       |
 329 `------------------------------------------------------------------*/
 330
 331 state_t *
 332 state_hash_lookup (size_t core_size, item_number_t *core)
 333 {
 334   state_t *probe = STATE_ALLOC (core_size);
 335   state_t *entry;
 336
 337   probe->nitems = core_size;
 338   memcpy (probe->items, core, core_size * sizeof (core[0]));
 339   entry = hash_lookup (state_table, probe);
 340   free (probe);
 341   return entry;
 342 }
 343
 344 /* All the decorated states, indexed by the state number.  */
 345 state_t **states = NULL;
 346
 347
 348 /*----------------------.
 349 | Free all the states.  |
 350 `----------------------*/
 351
 352 void
 353 states_free (void)
 354 {
 355   state_number_t i;
 356   for (i = 0; i < nstates; ++i)
 357     state_free (states[i]);
 358   free (states);
 359 }