1/* Type definitions for nondeterministic finite state machine for Bison.
2
3   Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006 Free Software
4   Foundation, Inc.
5
6   This file is part of Bison, the GNU Compiler Compiler.
7
8   Bison is free software; you can redistribute it and/or modify
9   it under the terms of the GNU General Public License as published by
10   the Free Software Foundation; either version 2, or (at your option)
11   any later version.
12
13   Bison is distributed in the hope that it will be useful,
14   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17
18   You should have received a copy of the GNU General Public License
19   along with Bison; see the file COPYING.  If not, write to
20   the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
21   Boston, MA 02110-1301, USA.  */
22
23#include <config.h>
24#include "system.h"
25
26#include <hash.h>
27
28#include "complain.h"
29#include "gram.h"
30#include "state.h"
31
32
33			/*-------------------.
34			| Shifts and Gotos.  |
35			`-------------------*/
36
37
38/*-----------------------------------------.
39| Create a new array of NUM shifts/gotos.  |
40`-----------------------------------------*/
41
42static transitions *
43transitions_new (int num, state **the_states)
44{
45  size_t states_size = num * sizeof *the_states;
46  transitions *res = xmalloc (offsetof (transitions, states) + states_size);
47  res->num = num;
48  memcpy (res->states, the_states, states_size);
49  return res;
50}
51
52
53/*-------------------------------------------------------.
54| Return the state such that SHIFTS contain a shift/goto |
55| to it on SYM.  Abort if none found.                    |
56`-------------------------------------------------------*/
57
58state *
59transitions_to (transitions *shifts, symbol_number sym)
60{
61  int j;
62  for (j = 0; ; j++)
63    {
64      assert (j < shifts->num);
65      if (TRANSITION_SYMBOL (shifts, j) == sym)
66	return shifts->states[j];
67    }
68}
69
70
71			/*--------------------.
72			| Error transitions.  |
73			`--------------------*/
74
75
76/*---------------------------------.
77| Create a new array of NUM errs.  |
78`---------------------------------*/
79
80errs *
81errs_new (int num, symbol **tokens)
82{
83  size_t symbols_size = num * sizeof *tokens;
84  errs *res = xmalloc (offsetof (errs, symbols) + symbols_size);
85  res->num = num;
86  memcpy (res->symbols, tokens, symbols_size);
87  return res;
88}
89
90
91
92
93			/*-------------.
94			| Reductions.  |
95			`-------------*/
96
97
98/*---------------------------------------.
99| Create a new array of NUM reductions.  |
100`---------------------------------------*/
101
102static reductions *
103reductions_new (int num, rule **reds)
104{
105  size_t rules_size = num * sizeof *reds;
106  reductions *res = xmalloc (offsetof (reductions, rules) + rules_size);
107  res->num = num;
108  res->look_ahead_tokens = NULL;
109  memcpy (res->rules, reds, rules_size);
110  return res;
111}
112
113
114
115			/*---------.
116			| States.  |
117			`---------*/
118
119
120state_number nstates = 0;
121/* FINAL_STATE is properly set by new_state when it recognizes its
122   accessing symbol: $end.  */
123state *final_state = NULL;
124
125
126/*------------------------------------------------------------------.
127| Create a new state with ACCESSING_SYMBOL, for those items.  Store |
128| it in the state hash table.                                       |
129`------------------------------------------------------------------*/
130
131state *
132state_new (symbol_number accessing_symbol,
133	   size_t nitems, item_number *core)
134{
135  state *res;
136  size_t items_size = nitems * sizeof *core;
137
138  assert (nstates < STATE_NUMBER_MAXIMUM);
139
140  res = xmalloc (offsetof (state, items) + items_size);
141  res->number = nstates++;
142  res->accessing_symbol = accessing_symbol;
143  res->transitions = NULL;
144  res->reductions = NULL;
145  res->errs = NULL;
146  res->consistent = 0;
147  res->solved_conflicts = NULL;
148
149  res->nitems = nitems;
150  memcpy (res->items, core, items_size);
151
152  state_hash_insert (res);
153
154  return res;
155}
156
157
158/*---------.
159| Free S.  |
160`---------*/
161
162static void
163state_free (state *s)
164{
165  free (s->transitions);
166  free (s->reductions);
167  free (s->errs);
168  free (s);
169}
170
171
172/*---------------------------.
173| Set the transitions of S.  |
174`---------------------------*/
175
176void
177state_transitions_set (state *s, int num, state **trans)
178{
179  assert (!s->transitions);
180  s->transitions = transitions_new (num, trans);
181}
182
183
184/*--------------------------.
185| Set the reductions of S.  |
186`--------------------------*/
187
188void
189state_reductions_set (state *s, int num, rule **reds)
190{
191  assert (!s->reductions);
192  s->reductions = reductions_new (num, reds);
193}
194
195
196int
197state_reduction_find (state *s, rule *r)
198{
199  int i;
200  reductions *reds = s->reductions;
201  for (i = 0; i < reds->num; ++i)
202    if (reds->rules[i] == r)
203      return i;
204  return -1;
205}
206
207
208/*--------------------.
209| Set the errs of S.  |
210`--------------------*/
211
212void
213state_errs_set (state *s, int num, symbol **tokens)
214{
215  assert (!s->errs);
216  s->errs = errs_new (num, tokens);
217}
218
219
220
221/*---------------------------------------------------.
222| Print on OUT all the look-ahead tokens such that S |
223| wants to reduce R.                                 |
224`---------------------------------------------------*/
225
226void
227state_rule_look_ahead_tokens_print (state *s, rule *r, FILE *out)
228{
229  /* Find the reduction we are handling.  */
230  reductions *reds = s->reductions;
231  int red = state_reduction_find (s, r);
232
233  /* Print them if there are.  */
234  if (reds->look_ahead_tokens && red != -1)
235    {
236      bitset_iterator biter;
237      int k;
238      char const *sep = "";
239      fprintf (out, "  [");
240      BITSET_FOR_EACH (biter, reds->look_ahead_tokens[red], k, 0)
241	{
242	  fprintf (out, "%s%s", sep, symbols[k]->tag);
243	  sep = ", ";
244	}
245      fprintf (out, "]");
246    }
247}
248
249
250/*---------------------.
251| A state hash table.  |
252`---------------------*/
253
254/* Initial capacity of states hash table.  */
255#define HT_INITIAL_CAPACITY 257
256
257static struct hash_table *state_table = NULL;
258
259/* Two states are equal if they have the same core items.  */
260static inline bool
261state_compare (state const *s1, state const *s2)
262{
263  size_t i;
264
265  if (s1->nitems != s2->nitems)
266    return false;
267
268  for (i = 0; i < s1->nitems; ++i)
269    if (s1->items[i] != s2->items[i])
270      return false;
271
272  return true;
273}
274
275static bool
276state_comparator (void const *s1, void const *s2)
277{
278  return state_compare (s1, s2);
279}
280
281static inline size_t
282state_hash (state const *s, size_t tablesize)
283{
284  /* Add up the state's item numbers to get a hash key.  */
285  size_t key = 0;
286  size_t i;
287  for (i = 0; i < s->nitems; ++i)
288    key += s->items[i];
289  return key % tablesize;
290}
291
292static size_t
293state_hasher (void const *s, size_t tablesize)
294{
295  return state_hash (s, tablesize);
296}
297
298
299/*-------------------------------.
300| Create the states hash table.  |
301`-------------------------------*/
302
303void
304state_hash_new (void)
305{
306  state_table = hash_initialize (HT_INITIAL_CAPACITY,
307				 NULL,
308				 state_hasher,
309				 state_comparator,
310				 NULL);
311}
312
313
314/*---------------------------------------------.
315| Free the states hash table, not the states.  |
316`---------------------------------------------*/
317
318void
319state_hash_free (void)
320{
321  hash_free (state_table);
322}
323
324
325/*-----------------------------------.
326| Insert S in the state hash table.  |
327`-----------------------------------*/
328
329void
330state_hash_insert (state *s)
331{
332  hash_insert (state_table, s);
333}
334
335
336/*------------------------------------------------------------------.
337| Find the state associated to the CORE, and return it.  If it does |
338| not exist yet, return NULL.                                       |
339`------------------------------------------------------------------*/
340
341state *
342state_hash_lookup (size_t nitems, item_number *core)
343{
344  size_t items_size = nitems * sizeof *core;
345  state *probe = xmalloc (offsetof (state, items) + items_size);
346  state *entry;
347
348  probe->nitems = nitems;
349  memcpy (probe->items, core, items_size);
350  entry = hash_lookup (state_table, probe);
351  free (probe);
352  return entry;
353}
354
355/* All the decorated states, indexed by the state number.  */
356state **states = NULL;
357
358
359/*----------------------.
360| Free all the states.  |
361`----------------------*/
362
363void
364states_free (void)
365{
366  state_number i;
367  for (i = 0; i < nstates; ++i)
368    state_free (states[i]);
369  free (states);
370}
371