src/state.c

/* Type definitions for the finite state machine for Bison.

   Copyright (C) 2001-2007, 2009-2012 Free Software Foundation, Inc.

   This file is part of Bison, the GNU Compiler Compiler.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>
#include "system.h"

#include <hash.h>

#include "complain.h"
#include "gram.h"
#include "state.h"
#include "print-xml.h"


                        /*-------------------.
                        | Shifts and Gotos.  |
                        `-------------------*/


/*-----------------------------------------.
| Create a new array of NUM shifts/gotos.  |
`-----------------------------------------*/

static transitions *
transitions_new (int num, state **the_states)
{
  size_t states_size = num * sizeof *the_states;
  transitions *res = xmalloc (offsetof (transitions, states) + states_size);
  res->num = num;
  memcpy (res->states, the_states, states_size);
  return res;
}


/*-------------------------------------------------------.
| Return the state such that SHIFTS contain a shift/goto |
| to it on SYM.  Abort if none found.                    |
`-------------------------------------------------------*/

state *
transitions_to (transitions *shifts, symbol_number sym)
{
  int j;
  for (j = 0; ; j++)
    {
      aver (j < shifts->num);
      if (TRANSITION_SYMBOL (shifts, j) == sym)
        return shifts->states[j];
    }
}


                        /*--------------------.
                        | Error transitions.  |
                        `--------------------*/


/*---------------------------------.
| Create a new array of NUM errs.  |
`---------------------------------*/

errs *
errs_new (int num, symbol **tokens)
{
  size_t symbols_size = num * sizeof *tokens;
  errs *res = xmalloc (offsetof (errs, symbols) + symbols_size);
  res->num = num;
  memcpy (res->symbols, tokens, symbols_size);
  return res;
}


                        /*-------------.
                        | Reductions.  |
                        `-------------*/


/*---------------------------------------.
| Create a new array of NUM reductions.  |
`---------------------------------------*/

static reductions *
reductions_new (int num, rule **reds)
{
  size_t rules_size = num * sizeof *reds;
  reductions *res = xmalloc (offsetof (reductions, rules) + rules_size);
  res->num = num;
  res->lookahead_tokens = NULL;
  memcpy (res->rules, reds, rules_size);
  return res;
}


                        /*---------.
                        | States.  |
                        `---------*/


state_number nstates = 0;
/* FINAL_STATE is properly set by new_state when it recognizes its
   accessing symbol: $end.  */
state *final_state = NULL;


/*------------------------------------------------------------------.
| Create a new state with ACCESSING_SYMBOL, for those items.  Store |
| it in the state hash table.                                       |
`------------------------------------------------------------------*/

state *
state_new (symbol_number accessing_symbol,
           size_t nitems, item_number *core)
{
  state *res;
  size_t items_size = nitems * sizeof *core;

  aver (nstates < STATE_NUMBER_MAXIMUM);

  res = xmalloc (offsetof (state, items) + items_size);
  res->number = nstates++;
  res->accessing_symbol = accessing_symbol;
  res->transitions = NULL;
  res->reductions = NULL;
  res->errs = NULL;
  res->state_list = NULL;
  res->consistent = 0;
  res->solved_conflicts = NULL;
  res->solved_conflicts_xml = NULL;

  res->nitems = nitems;
  memcpy (res->items, core, items_size);

  state_hash_insert (res);

  return res;
}

state *
state_new_isocore (state const *s)
{
  state *res;
  size_t items_size = s->nitems * sizeof *s->items;

  aver (nstates < STATE_NUMBER_MAXIMUM);

  res = xmalloc (offsetof (state, items) + items_size);
  res->number = nstates++;
  res->accessing_symbol = s->accessing_symbol;
  res->transitions =
    transitions_new (s->transitions->num, s->transitions->states);
  res->reductions = reductions_new (s->reductions->num, s->reductions->rules);
  res->errs = NULL;
  res->state_list = NULL;
  res->consistent = s->consistent;
  res->solved_conflicts = NULL;
  res->solved_conflicts_xml = NULL;

  res->nitems = s->nitems;
  memcpy (res->items, s->items, items_size);

  return res;
}


/*---------.
| Free S.  |
`---------*/

static void
state_free (state *s)
{
  free (s->transitions);
  free (s->reductions);
  free (s->errs);
  free (s);
}


/*---------------------------.
| Set the transitions of S.  |
`---------------------------*/

void
state_transitions_set (state *s, int num, state **trans)
{
  aver (!s->transitions);
  s->transitions = transitions_new (num, trans);
}


/*--------------------------.
| Set the reductions of S.  |
`--------------------------*/

void
state_reductions_set (state *s, int num, rule **reds)
{
  aver (!s->reductions);
  s->reductions = reductions_new (num, reds);
}


int
state_reduction_find (state *s, rule *r)
{
  int i;
  reductions *reds = s->reductions;
  for (i = 0; i < reds->num; ++i)
    if (reds->rules[i] == r)
      return i;
  return -1;
}


/*--------------------.
| Set the errs of S.  |
`--------------------*/

void
state_errs_set (state *s, int num, symbol **tokens)
{
  aver (!s->errs);
  s->errs = errs_new (num, tokens);
}


/*--------------------------------------------------.
| Print on OUT all the lookahead tokens such that S |
| wants to reduce R.                                |
`--------------------------------------------------*/

void
state_rule_lookahead_tokens_print (state *s, rule *r, FILE *out)
{
  /* Find the reduction we are handling.  */
  reductions *reds = s->reductions;
  int red = state_reduction_find (s, r);

  /* Print them if there are.  */
  if (reds->lookahead_tokens && red != -1)
    {
      bitset_iterator biter;
      int k;
      char const *sep = "";
      fprintf (out, "  [");
      BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
        {
          fprintf (out, "%s%s", sep, symbols[k]->tag);
          sep = ", ";
        }
      fprintf (out, "]");
    }
}

void
state_rule_lookahead_tokens_print_xml (state *s, rule *r,
                                       FILE *out, int level)
{
  /* Find the reduction we are handling.  */
  reductions *reds = s->reductions;
  int red = state_reduction_find (s, r);

  /* Print them if there are.  */
  if (reds->lookahead_tokens && red != -1)
    {
      bitset_iterator biter;
      int k;
      xml_puts (out, level, "<lookaheads>");
      BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
        {
          xml_printf (out, level + 1, "<symbol>%s</symbol>",
                      xml_escape (symbols[k]->tag));
        }
      xml_puts (out, level, "</lookaheads>");
    }
}


/*---------------------.
| A state hash table.  |
`---------------------*/

/* Initial capacity of states hash table.  */
#define HT_INITIAL_CAPACITY 257

static struct hash_table *state_table = NULL;

/* Two states are equal if they have the same core items.  */
static inline bool
state_compare (state const *s1, state const *s2)
{
  size_t i;

  if (s1->nitems != s2->nitems)
    return false;

  for (i = 0; i < s1->nitems; ++i)
    if (s1->items[i] != s2->items[i])
      return false;

  return true;
}

static bool
state_comparator (void const *s1, void const *s2)
{
  return state_compare (s1, s2);
}

static inline size_t
state_hash (state const *s, size_t tablesize)
{
  /* Add up the state's item numbers to get a hash key.  */
  size_t key = 0;
  size_t i;
  for (i = 0; i < s->nitems; ++i)
    key += s->items[i];
  return key % tablesize;
}

static size_t
state_hasher (void const *s, size_t tablesize)
{
  return state_hash (s, tablesize);
}


/*-------------------------------.
| Create the states hash table.  |
`-------------------------------*/

void
state_hash_new (void)
{
  state_table = hash_initialize (HT_INITIAL_CAPACITY,
                                 NULL,
                                 state_hasher,
                                 state_comparator,
                                 NULL);
}


/*---------------------------------------------.
| Free the states hash table, not the states.  |
`---------------------------------------------*/

void
state_hash_free (void)
{
  hash_free (state_table);
}


/*-----------------------------------.
| Insert S in the state hash table.  |
`-----------------------------------*/

void
state_hash_insert (state *s)
{
  if (!hash_insert (state_table, s))
    xalloc_die ();
}


/*------------------------------------------------------------------.
| Find the state associated to the CORE, and return it.  If it does |
| not exist yet, return NULL.                                       |
`------------------------------------------------------------------*/

state *
state_hash_lookup (size_t nitems, item_number *core)
{
  size_t items_size = nitems * sizeof *core;
  state *probe = xmalloc (offsetof (state, items) + items_size);
  state *entry;

  probe->nitems = nitems;
  memcpy (probe->items, core, items_size);
  entry = hash_lookup (state_table, probe);
  free (probe);
  return entry;
}


/*--------------------------------------------------------.
| Record S and all states reachable from S in REACHABLE.  |
`--------------------------------------------------------*/

static void
state_record_reachable_states (state *s, bitset reachable)
{
  if (bitset_test (reachable, s->number))
    return;
  bitset_set (reachable, s->number);
  {
    int i;
    for (i = 0; i < s->transitions->num; ++i)
      if (!TRANSITION_IS_DISABLED (s->transitions, i))
        state_record_reachable_states (s->transitions->states[i], reachable);
  }
}

void
state_remove_unreachable_states (state_number old_to_new[])
{
  state_number nstates_reachable = 0;
  bitset reachable = bitset_create (nstates, BITSET_FIXED);
  state_record_reachable_states (states[0], reachable);
  {
    state_number i;
    for (i = 0; i < nstates; ++i)
      {
        if (bitset_test (reachable, states[i]->number))
          {
            states[nstates_reachable] = states[i];
            states[nstates_reachable]->number = nstates_reachable;
            old_to_new[i] = nstates_reachable++;
          }
        else
          {
            state_free (states[i]);
            old_to_new[i] = nstates;
          }
      }
  }
  nstates = nstates_reachable;
  bitset_free (reachable);
}

/* All the decorated states, indexed by the state number.  */
state **states = NULL;


/*----------------------.
| Free all the states.  |
`----------------------*/

void
states_free (void)
{
  state_number i;
  for (i = 0; i < nstates; ++i)
    state_free (states[i]);
  free (states);
}
Commit	Line	Data
	1	/* Type definitions for the finite state machine for Bison.
	2
	3	Copyright (C) 2001-2007, 2009-2012 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	#include <config.h>
	21	#include "system.h"
	22
	23	#include <hash.h>
	24
	25	#include "complain.h"
	26	#include "gram.h"
	27	#include "state.h"
	28	#include "print-xml.h"
	29
	30
	31	/*-------------------.
	32	\| Shifts and Gotos. \|
	33	`-------------------*/
	34
	35
	36	/*-----------------------------------------.
	37	\| Create a new array of NUM shifts/gotos. \|
	38	`-----------------------------------------*/
	39
	40	static transitions *
	41	transitions_new (int num, state **the_states)
	42	{
	43	size_t states_size = num * sizeof *the_states;
	44	transitions *res = xmalloc (offsetof (transitions, states) + states_size);
	45	res->num = num;
	46	memcpy (res->states, the_states, states_size);
	47	return res;
	48	}
	49
	50
	51	/*-------------------------------------------------------.
	52	\| Return the state such that SHIFTS contain a shift/goto \|
	53	\| to it on SYM. Abort if none found. \|
	54	`-------------------------------------------------------*/
	55
	56	state *
	57	transitions_to (transitions *shifts, symbol_number sym)
	58	{
	59	int j;
	60	for (j = 0; ; j++)
	61	{
	62	aver (j < shifts->num);
	63	if (TRANSITION_SYMBOL (shifts, j) == sym)
	64	return shifts->states[j];
	65	}
	66	}
	67
	68
	69	/*--------------------.
	70	\| Error transitions. \|
	71	`--------------------*/
	72
	73
	74	/*---------------------------------.
	75	\| Create a new array of NUM errs. \|
	76	`---------------------------------*/
	77
	78	errs *
	79	errs_new (int num, symbol **tokens)
	80	{
	81	size_t symbols_size = num * sizeof *tokens;
	82	errs *res = xmalloc (offsetof (errs, symbols) + symbols_size);
	83	res->num = num;
	84	memcpy (res->symbols, tokens, symbols_size);
	85	return res;
	86	}
	87
	88
	89
	90
	91	/*-------------.
	92	\| Reductions. \|
	93	`-------------*/
	94
	95
	96	/*---------------------------------------.
	97	\| Create a new array of NUM reductions. \|
	98	`---------------------------------------*/
	99
	100	static reductions *
	101	reductions_new (int num, rule **reds)
	102	{
	103	size_t rules_size = num * sizeof *reds;
	104	reductions *res = xmalloc (offsetof (reductions, rules) + rules_size);
	105	res->num = num;
	106	res->lookahead_tokens = NULL;
	107	memcpy (res->rules, reds, rules_size);
	108	return res;
	109	}
	110
	111
	112
	113	/*---------.
	114	\| States. \|
	115	`---------*/
	116
	117
	118	state_number nstates = 0;
	119	/* FINAL_STATE is properly set by new_state when it recognizes its
	120	accessing symbol: $end. */
	121	state *final_state = NULL;
	122
	123
	124	/*------------------------------------------------------------------.
	125	\| Create a new state with ACCESSING_SYMBOL, for those items. Store \|
	126	\| it in the state hash table. \|
	127	`------------------------------------------------------------------*/
	128
	129	state *
	130	state_new (symbol_number accessing_symbol,
	131	size_t nitems, item_number *core)
	132	{
	133	state *res;
	134	size_t items_size = nitems * sizeof *core;
	135
	136	aver (nstates < STATE_NUMBER_MAXIMUM);
	137
	138	res = xmalloc (offsetof (state, items) + items_size);
	139	res->number = nstates++;
	140	res->accessing_symbol = accessing_symbol;
	141	res->transitions = NULL;
	142	res->reductions = NULL;
	143	res->errs = NULL;
	144	res->state_list = NULL;
	145	res->consistent = 0;
	146	res->solved_conflicts = NULL;
	147	res->solved_conflicts_xml = 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	state *
	158	state_new_isocore (state const *s)
	159	{
	160	state *res;
	161	size_t items_size = s->nitems * sizeof *s->items;
	162
	163	aver (nstates < STATE_NUMBER_MAXIMUM);
	164
	165	res = xmalloc (offsetof (state, items) + items_size);
	166	res->number = nstates++;
	167	res->accessing_symbol = s->accessing_symbol;
	168	res->transitions =
	169	transitions_new (s->transitions->num, s->transitions->states);
	170	res->reductions = reductions_new (s->reductions->num, s->reductions->rules);
	171	res->errs = NULL;
	172	res->state_list = NULL;
	173	res->consistent = s->consistent;
	174	res->solved_conflicts = NULL;
	175	res->solved_conflicts_xml = NULL;
	176
	177	res->nitems = s->nitems;
	178	memcpy (res->items, s->items, items_size);
	179
	180	return res;
	181	}
	182
	183
	184	/*---------.
	185	\| Free S. \|
	186	`---------*/
	187
	188	static void
	189	state_free (state *s)
	190	{
	191	free (s->transitions);
	192	free (s->reductions);
	193	free (s->errs);
	194	free (s);
	195	}
	196
	197
	198	/*---------------------------.
	199	\| Set the transitions of S. \|
	200	`---------------------------*/
	201
	202	void
	203	state_transitions_set (state s, int num, state *trans)
	204	{
	205	aver (!s->transitions);
	206	s->transitions = transitions_new (num, trans);
	207	}
	208
	209
	210	/*--------------------------.
	211	\| Set the reductions of S. \|
	212	`--------------------------*/
	213
	214	void
	215	state_reductions_set (state s, int num, rule *reds)
	216	{
	217	aver (!s->reductions);
	218	s->reductions = reductions_new (num, reds);
	219	}
	220
	221
	222	int
	223	state_reduction_find (state s, rule r)
	224	{
	225	int i;
	226	reductions *reds = s->reductions;
	227	for (i = 0; i < reds->num; ++i)
	228	if (reds->rules[i] == r)
	229	return i;
	230	return -1;
	231	}
	232
	233
	234	/*--------------------.
	235	\| Set the errs of S. \|
	236	`--------------------*/
	237
	238	void
	239	state_errs_set (state s, int num, symbol *tokens)
	240	{
	241	aver (!s->errs);
	242	s->errs = errs_new (num, tokens);
	243	}
	244
	245
	246
	247	/*--------------------------------------------------.
	248	\| Print on OUT all the lookahead tokens such that S \|
	249	\| wants to reduce R. \|
	250	`--------------------------------------------------*/
	251
	252	void
	253	state_rule_lookahead_tokens_print (state s, rule r, FILE *out)
	254	{
	255	/* Find the reduction we are handling. */
	256	reductions *reds = s->reductions;
	257	int red = state_reduction_find (s, r);
	258
	259	/* Print them if there are. */
	260	if (reds->lookahead_tokens && red != -1)
	261	{
	262	bitset_iterator biter;
	263	int k;
	264	char const *sep = "";
	265	fprintf (out, " [");
	266	BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
	267	{
	268	fprintf (out, "%s%s", sep, symbols[k]->tag);
	269	sep = ", ";
	270	}
	271	fprintf (out, "]");
	272	}
	273	}
	274
	275	void
	276	state_rule_lookahead_tokens_print_xml (state s, rule r,
	277	FILE *out, int level)
	278	{
	279	/* Find the reduction we are handling. */
	280	reductions *reds = s->reductions;
	281	int red = state_reduction_find (s, r);
	282
	283	/* Print them if there are. */
	284	if (reds->lookahead_tokens && red != -1)
	285	{
	286	bitset_iterator biter;
	287	int k;
	288	xml_puts (out, level, "<lookaheads>");
	289	BITSET_FOR_EACH (biter, reds->lookahead_tokens[red], k, 0)
	290	{
	291	xml_printf (out, level + 1, "<symbol>%s</symbol>",
	292	xml_escape (symbols[k]->tag));
	293	}
	294	xml_puts (out, level, "</lookaheads>");
	295	}
	296	}
	297
	298
	299	/*---------------------.
	300	\| A state hash table. \|
	301	`---------------------*/
	302
	303	/* Initial capacity of states hash table. */
	304	#define HT_INITIAL_CAPACITY 257
	305
	306	static struct hash_table *state_table = NULL;
	307
	308	/* Two states are equal if they have the same core items. */
	309	static inline bool
	310	state_compare (state const s1, state const s2)
	311	{
	312	size_t i;
	313
	314	if (s1->nitems != s2->nitems)
	315	return false;
	316
	317	for (i = 0; i < s1->nitems; ++i)
	318	if (s1->items[i] != s2->items[i])
	319	return false;
	320
	321	return true;
	322	}
	323
	324	static bool
	325	state_comparator (void const s1, void const s2)
	326	{
	327	return state_compare (s1, s2);
	328	}
	329
	330	static inline size_t
	331	state_hash (state const *s, size_t tablesize)
	332	{
	333	/* Add up the state's item numbers to get a hash key. */
	334	size_t key = 0;
	335	size_t i;
	336	for (i = 0; i < s->nitems; ++i)
	337	key += s->items[i];
	338	return key % tablesize;
	339	}
	340
	341	static size_t
	342	state_hasher (void const *s, size_t tablesize)
	343	{
	344	return state_hash (s, tablesize);
	345	}
	346
	347
	348	/*-------------------------------.
	349	\| Create the states hash table. \|
	350	`-------------------------------*/
	351
	352	void
	353	state_hash_new (void)
	354	{
	355	state_table = hash_initialize (HT_INITIAL_CAPACITY,
	356	NULL,
	357	state_hasher,
	358	state_comparator,
	359	NULL);
	360	}
	361
	362
	363	/*---------------------------------------------.
	364	\| Free the states hash table, not the states. \|
	365	`---------------------------------------------*/
	366
	367	void
	368	state_hash_free (void)
	369	{
	370	hash_free (state_table);
	371	}
	372
	373
	374	/*-----------------------------------.
	375	\| Insert S in the state hash table. \|
	376	`-----------------------------------*/
	377
	378	void
	379	state_hash_insert (state *s)
	380	{
	381	if (!hash_insert (state_table, s))
	382	xalloc_die ();
	383	}
	384
	385
	386	/*------------------------------------------------------------------.
	387	\| Find the state associated to the CORE, and return it. If it does \|
	388	\| not exist yet, return NULL. \|
	389	`------------------------------------------------------------------*/
	390
	391	state *
	392	state_hash_lookup (size_t nitems, item_number *core)
	393	{
	394	size_t items_size = nitems * sizeof *core;
	395	state *probe = xmalloc (offsetof (state, items) + items_size);
	396	state *entry;
	397
	398	probe->nitems = nitems;
	399	memcpy (probe->items, core, items_size);
	400	entry = hash_lookup (state_table, probe);
	401	free (probe);
	402	return entry;
	403	}
	404
	405
	406	/*--------------------------------------------------------.
	407	\| Record S and all states reachable from S in REACHABLE. \|
	408	`--------------------------------------------------------*/
	409
	410	static void
	411	state_record_reachable_states (state *s, bitset reachable)
	412	{
	413	if (bitset_test (reachable, s->number))
	414	return;
	415	bitset_set (reachable, s->number);
	416	{
	417	int i;
	418	for (i = 0; i < s->transitions->num; ++i)
	419	if (!TRANSITION_IS_DISABLED (s->transitions, i))
	420	state_record_reachable_states (s->transitions->states[i], reachable);
	421	}
	422	}
	423
	424	void
	425	state_remove_unreachable_states (state_number old_to_new[])
	426	{
	427	state_number nstates_reachable = 0;
	428	bitset reachable = bitset_create (nstates, BITSET_FIXED);
	429	state_record_reachable_states (states[0], reachable);
	430	{
	431	state_number i;
	432	for (i = 0; i < nstates; ++i)
	433	{
	434	if (bitset_test (reachable, states[i]->number))
	435	{
	436	states[nstates_reachable] = states[i];
	437	states[nstates_reachable]->number = nstates_reachable;
	438	old_to_new[i] = nstates_reachable++;
	439	}
	440	else
	441	{
	442	state_free (states[i]);
	443	old_to_new[i] = nstates;
	444	}
	445	}
	446	}
	447	nstates = nstates_reachable;
	448	bitset_free (reachable);
	449	}
	450
	451	/* All the decorated states, indexed by the state number. */
	452	state **states = NULL;
	453
	454
	455	/*----------------------.
	456	\| Free all the states. \|
	457	`----------------------*/
	458
	459	void
	460	states_free (void)
	461	{
	462	state_number i;
	463	for (i = 0; i < nstates; ++i)
	464	state_free (states[i]);
	465	free (states);
	466	}