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 SHIFTS_ALLOC(Nshifts)                                           \
  39   (shifts_t *) xcalloc ((unsigned) (sizeof (shifts_t)                   \
  40                                   + (Nshifts - 1) * sizeof (state_number_t)), 1)
  41
  42 static shifts_t *
  43 shifts_new (int nshifts, state_number_t *shifts)
  44 {
  45   shifts_t *res = SHIFTS_ALLOC (nshifts);
  46   res->nshifts = nshifts;
  47   memcpy (res->shifts, shifts, nshifts * sizeof (shifts[0]));
  48   return res;
  49 }
  50
  51
  52
  53
  54                         /*--------------------.
  55                         | Error transitions.  |
  56                         `--------------------*/
  57
  58
  59 /*-------------------------------.
  60 | Create a new array of N errs.  |
  61 `-------------------------------*/
  62
  63 #define ERRS_ALLOC(Nerrs)                                               \
  64   (errs *) xcalloc ((unsigned) (sizeof (errs)                           \
  65                                   + (Nerrs - 1) * sizeof (short)), 1)
  66
  67
  68 errs *
  69 errs_new (int n)
  70 {
  71   errs *res = ERRS_ALLOC (n);
  72   res->nerrs = n;
  73   return res;
  74 }
  75
  76
  77 errs *
  78 errs_dup (errs *src)
  79 {
  80   errs *res = errs_new (src->nerrs);
  81   memcpy (res->errs, src->errs, src->nerrs * sizeof (src->errs[0]));
  82   return res;
  83 }
  84
  85
  86
  87
  88                         /*-------------.
  89                         | Reductions.  |
  90                         `-------------*/
  91
  92
  93 /*-------------------------------------.
  94 | Create a new array of N reductions.  |
  95 `-------------------------------------*/
  96
  97 #define REDUCTIONS_ALLOC(Nreductions)                                   \
  98   (reductions *) xcalloc ((unsigned) (sizeof (reductions)               \
  99                                   + (Nreductions - 1) * sizeof (short)), 1)
 100
 101 reductions *
 102 reductions_new (int n)
 103 {
 104   reductions *res = REDUCTIONS_ALLOC (n);
 105   res->nreds = n;
 106   return res;
 107 }
 108
 109
 110
 111                         /*---------.
 112                         | States.  |
 113                         `---------*/
 114
 115
 116 state_number_t nstates = 0;
 117 /* FINAL_STATE is properly set by new_state when it recognizes its
 118    accessing symbol: EOF.  */
 119 state_t *final_state = NULL;
 120
 121 #define STATE_ALLOC(Nitems)                                             \
 122   (state_t *) xcalloc ((unsigned) (sizeof (state_t)                     \
 123                                   + (Nitems - 1) * sizeof (item_number_t)), 1)
 124
 125 /*------------------------------------------------------------.
 126 | Create a new state with ACCESSING_SYMBOL, for those items.  |
 127 `------------------------------------------------------------*/
 128
 129 state_t *
 130 state_new (symbol_number_t accessing_symbol,
 131            size_t core_size, item_number_t *core)
 132 {
 133   state_t *res;
 134
 135   if (nstates >= STATE_NUMBER_MAX)
 136     fatal (_("too many states (max %d)"), STATE_NUMBER_MAX);
 137
 138   res = STATE_ALLOC (core_size);
 139   res->accessing_symbol = accessing_symbol;
 140   res->number = nstates;
 141   ++nstates;
 142   res->solved_conflicts = NULL;
 143
 144   res->nitems = core_size;
 145   memcpy (res->items, core, core_size * sizeof (core[0]));
 146
 147   return res;
 148 }
 149
 150
 151 /*--------------------------.
 152 | Set the shifts of STATE.  |
 153 `--------------------------*/
 154
 155 void
 156 state_shifts_set (state_t *state, int nshifts, state_number_t *shifts)
 157 {
 158   state->shifts = shifts_new (nshifts, shifts);
 159 }
 160
 161
 162
 163 /*--------------------------------------------------------------.
 164 | Print on OUT all the lookaheads such that this STATE wants to |
 165 | reduce this RULE.                                             |
 166 `--------------------------------------------------------------*/
 167
 168 void
 169 state_rule_lookaheads_print (state_t *state, rule_t *rule, FILE *out)
 170 {
 171   int j, k;
 172   int nlookaheads = 0;
 173   /* Count the number of lookaheads corresponding to this rule.  */
 174   for (j = 0; j < state->nlookaheads; ++j)
 175     for (k = 0; k < ntokens; ++k)
 176       if (bitset_test (state->lookaheads[j], k)
 177           && state->lookaheads_rule[j]->number == rule->number)
 178         nlookaheads++;
 179
 180   /* Print them if there are.  */
 181   if (nlookaheads)
 182     {
 183       fprintf (out, "  [");
 184       for (j = 0; j < state->nlookaheads; ++j)
 185         for (k = 0; k < ntokens; ++k)
 186           if (bitset_test (state->lookaheads[j], k)
 187               && state->lookaheads_rule[j]->number == rule->number)
 188             fprintf (out, "%s%s",
 189                      symbol_tag_get (symbols[k]),
 190                      --nlookaheads ? ", " : "");
 191       fprintf (out, "]");
 192     }
 193 }
 194
 195
 196 /*----------------------.
 197 | A state hash table.  |
 198 `----------------------*/
 199
 200 /* Initial capacity of states hash table.  */
 201 #define HT_INITIAL_CAPACITY 257
 202
 203 static struct hash_table *state_table = NULL;
 204
 205 /* Two states are equal if they have the same core items.  */
 206 static bool
 207 state_compare (const state_t *s1, const state_t *s2)
 208 {
 209   int i;
 210
 211   if (s1->nitems != s2->nitems)
 212     return FALSE;
 213
 214   for (i = 0; i < s1->nitems; ++i)
 215     if (s1->items[i] != s2->items[i])
 216       return FALSE;
 217
 218   return TRUE;
 219 }
 220
 221 static unsigned int
 222 state_hash (const state_t *state, unsigned int tablesize)
 223 {
 224   /* Add up the state's item numbers to get a hash key.  */
 225   int key = 0;
 226   int i;
 227   for (i = 0; i < state->nitems; ++i)
 228     key += state->items[i];
 229   return key % tablesize;
 230 }
 231
 232
 233 /*-------------------------------.
 234 | Create the states hash table.  |
 235 `-------------------------------*/
 236
 237 void
 238 state_hash_new (void)
 239 {
 240   state_table = hash_initialize (HT_INITIAL_CAPACITY,
 241                                  NULL,
 242                                  (Hash_hasher) state_hash,
 243                                  (Hash_comparator) state_compare,
 244                                  (Hash_data_freer) NULL);
 245 }
 246
 247
 248 /*---------------------------------------------.
 249 | Free the states hash table, not the states.  |
 250 `---------------------------------------------*/
 251
 252 void
 253 state_hash_free (void)
 254 {
 255   hash_free (state_table);
 256 }
 257
 258
 259 /*---------------------------------------.
 260 | Insert STATE in the state hash table.  |
 261 `---------------------------------------*/
 262
 263 void
 264 state_hash_insert (state_t *state)
 265 {
 266   hash_insert (state_table, state);
 267 }
 268
 269
 270 /*------------------------------------------------------------------.
 271 | Find the state associated to the CORE, and return it.  If it does |
 272 | not exist yet, return NULL.                                       |
 273 `------------------------------------------------------------------*/
 274
 275 state_t *
 276 state_hash_lookup (size_t core_size, item_number_t *core)
 277 {
 278   state_t *probe = STATE_ALLOC (core_size);
 279   state_t *entry;
 280
 281   probe->nitems = core_size;
 282   memcpy (probe->items, core, core_size * sizeof (core[0]));
 283   entry = hash_lookup (state_table, probe);
 284   free (probe);
 285   return entry;
 286 }
 287
 288 /* All the decorated states, indexed by the state number.  */
 289 state_t **states = NULL;
 290
 291
 292 /*----------------------.
 293 | Free all the states.  |
 294 `----------------------*/
 295
 296 void
 297 states_free (void)
 298 {
 299   state_number_t i;
 300
 301   for (i = 0; i < nstates; ++i)
 302     {
 303       free (states[i]->shifts);
 304       XFREE (states[i]->reductions);
 305       free (states[i]->errs);
 306       free (states[i]);
 307     }
 308   XFREE (states);
 309 }