]> git.saurik.com Git - bison.git/blobdiff - src/state.c
* doc/bison.texinfo (Stack Overflow): xref to Recursion.
[bison.git] / src / state.c
index 7c3b69210e463e3166538a97fd01b3ac7c1358bb..71914025c96ac2112921bad287f0d5cde056c2b8 100644 (file)
@@ -1,5 +1,5 @@
 /* Type definitions for nondeterministic finite state machine for bison,
 /* Type definitions for nondeterministic finite state machine for bison,
-   Copyright 2001 Free Software Foundation, Inc.
+   Copyright (C) 2001, 2002  Free Software Foundation, Inc.
 
    This file is part of Bison, the GNU Compiler Compiler.
 
 
    This file is part of Bison, the GNU Compiler Compiler.
 
 
 
 #include "system.h"
 
 
 #include "system.h"
+#include "hash.h"
+#include "complain.h"
+#include "gram.h"
 #include "state.h"
 
 #include "state.h"
 
-/*---------------------------------.
-| Create a new array of N shitfs.  |
-`---------------------------------*/
 
 
-shifts *
-shifts_new (int n)
+                       /*-------------------.
+                       | Shifts and Gotos.  |
+                       `-------------------*/
+
+
+/*---------------------------------------.
+| Create a new array of N shifts/gotos.  |
+`---------------------------------------*/
+
+#define TRANSITIONS_ALLOC(Num)                                         \
+  (transitions_t *) xcalloc ((sizeof (transitions_t)                   \
+                                  + (Num - 1) * sizeof (state_t *)), 1)
+
+static transitions_t *
+transitions_new (int num, state_t **the_states)
+{
+  transitions_t *res = TRANSITIONS_ALLOC (num);
+  res->num = num;
+  memcpy (res->states, the_states, num * sizeof (the_states[0]));
+  return res;
+}
+
+
+/*-------------------------------------------------------------------.
+| Return the state such these TRANSITIONS contain a shift/goto to it |
+| on SYMBOL.  Aborts if none found.                                  |
+`-------------------------------------------------------------------*/
+
+state_t *
+transitions_to (transitions_t *shifts, symbol_number_t s)
+{
+  int j;
+  for (j = 0; j < shifts->num; j++)
+    if (TRANSITION_SYMBOL (shifts, j) == s)
+      return shifts->states[j];
+  abort ();
+}
+
+
+                       /*--------------------.
+                       | Error transitions.  |
+                       `--------------------*/
+
+
+/*-------------------------------.
+| Create a new array of N errs.  |
+`-------------------------------*/
+
+#define ERRS_ALLOC(Nerrs)                              \
+  (errs_t *) xcalloc ((sizeof (errs_t)                 \
+                      + (Nerrs - 1) * sizeof (symbol_t *)), 1)
+
+
+errs_t *
+errs_new (int num, symbol_t **tokens)
+{
+  errs_t *res = ERRS_ALLOC (num);
+  res->num = num;
+  memcpy (res->symbols, tokens, num * sizeof (tokens[0]));
+  return res;
+}
+
+
+
+
+                       /*-------------.
+                       | Reductions.  |
+                       `-------------*/
+
+
+/*-------------------------------------.
+| Create a new array of N reductions.  |
+`-------------------------------------*/
+
+#define REDUCTIONS_ALLOC(Nreductions)                          \
+  (reductions_t *) xcalloc ((sizeof (reductions_t)             \
+                            + (Nreductions - 1) * sizeof (rule_t *)), 1)
+
+static reductions_t *
+reductions_new (int num, rule_t **reductions)
 {
 {
-  shifts *res = SHIFTS_ALLOC (n);
-  res->nshifts = n;
+  reductions_t *res = REDUCTIONS_ALLOC (num);
+  res->num = num;
+  memcpy (res->rules, reductions, num * sizeof (reductions[0]));
+  res->lookaheads = NULL;
   return res;
 }
   return res;
 }
+
+
+
+                       /*---------.
+                       | States.  |
+                       `---------*/
+
+
+state_number_t nstates = 0;
+/* FINAL_STATE is properly set by new_state when it recognizes its
+   accessing symbol: $end.  */
+state_t *final_state = NULL;
+
+#define STATE_ALLOC(Nitems)                                            \
+  (state_t *) xcalloc ((sizeof (state_t)                               \
+                       + (Nitems - 1) * sizeof (item_number_t)), 1)
+
+/*------------------------------------------------------------------.
+| Create a new state with ACCESSING_SYMBOL, for those items.  Store |
+| it in the state hash table.                                       |
+`------------------------------------------------------------------*/
+
+state_t *
+state_new (symbol_number_t accessing_symbol,
+          size_t core_size, item_number_t *core)
+{
+  state_t *res;
+
+  if (nstates >= STATE_NUMBER_MAX)
+    fatal (_("too many states (max %d)"), STATE_NUMBER_MAX);
+
+  res = STATE_ALLOC (core_size);
+  res->accessing_symbol = accessing_symbol;
+  res->number = nstates;
+  ++nstates;
+  res->solved_conflicts = NULL;
+
+  res->nitems = core_size;
+  memcpy (res->items, core, core_size * sizeof (core[0]));
+
+  state_hash_insert (res);
+
+  return res;
+}
+
+
+/*-------------.
+| Free STATE.  |
+`-------------*/
+
+static void
+state_free (state_t *state)
+{
+  free (state->transitions);
+  free (state->reductions);
+  free (state->errs);
+  free (state);
+}
+
+
+/*-------------------------------.
+| Set the transitions of STATE.  |
+`-------------------------------*/
+
+void
+state_transitions_set (state_t *state, int num, state_t **transitions)
+{
+  assert (!state->transitions);
+  state->transitions = transitions_new (num, transitions);
+}
+
+
+/*------------------------------.
+| Set the reductions of STATE.  |
+`------------------------------*/
+
+void
+state_reductions_set (state_t *state, int num, rule_t **reductions)
+{
+  assert (!state->reductions);
+  state->reductions = reductions_new (num, reductions);
+}
+
+
+int
+state_reduction_find (state_t *state, rule_t *rule)
+{
+  int i;
+  reductions_t *reds = state->reductions;
+  for (i = 0; i < reds->num; ++i)
+    if (reds->rules[i] == rule)
+      return i;
+  return -1;
+}
+
+
+/*------------------------.
+| Set the errs of STATE.  |
+`------------------------*/
+
+void
+state_errs_set (state_t *state, int num, symbol_t **tokens)
+{
+  assert (!state->errs);
+  state->errs = errs_new (num, tokens);
+}
+
+
+
+/*--------------------------------------------------------------.
+| Print on OUT all the lookaheads such that this STATE wants to |
+| reduce this RULE.                                             |
+`--------------------------------------------------------------*/
+
+void
+state_rule_lookaheads_print (state_t *state, rule_t *rule, FILE *out)
+{
+  /* Find the reduction we are handling.  */
+  reductions_t *reds = state->reductions;
+  int red = state_reduction_find (state, rule);
+
+  /* Print them if there are.  */
+  if (reds->lookaheads && red != -1)
+    {
+      bitset_iterator biter;
+      int k;
+      int not_first = 0;
+      fprintf (out, "  [");
+      BITSET_FOR_EACH (biter, reds->lookaheads[red], k, 0)
+       fprintf (out, "%s%s",
+                not_first++ ? ", " : "",
+                symbols[k]->tag);
+      fprintf (out, "]");
+    }
+}
+
+
+/*----------------------.
+| 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 bool
+state_compare (const state_t *s1, const state_t *s2)
+{
+  int 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 unsigned int
+state_hash (const state_t *state, unsigned int tablesize)
+{
+  /* Add up the state's item numbers to get a hash key.  */
+  int key = 0;
+  int i;
+  for (i = 0; i < state->nitems; ++i)
+    key += state->items[i];
+  return key % tablesize;
+}
+
+
+/*-------------------------------.
+| Create the states hash table.  |
+`-------------------------------*/
+
+void
+state_hash_new (void)
+{
+  state_table = hash_initialize (HT_INITIAL_CAPACITY,
+                                NULL,
+                                (Hash_hasher) state_hash,
+                                (Hash_comparator) state_compare,
+                                (Hash_data_freer) NULL);
+}
+
+
+/*---------------------------------------------.
+| Free the states hash table, not the states.  |
+`---------------------------------------------*/
+
+void
+state_hash_free (void)
+{
+  hash_free (state_table);
+}
+
+
+/*---------------------------------------.
+| Insert STATE in the state hash table.  |
+`---------------------------------------*/
+
+void
+state_hash_insert (state_t *state)
+{
+  hash_insert (state_table, state);
+}
+
+
+/*------------------------------------------------------------------.
+| Find the state associated to the CORE, and return it.  If it does |
+| not exist yet, return NULL.                                       |
+`------------------------------------------------------------------*/
+
+state_t *
+state_hash_lookup (size_t core_size, item_number_t *core)
+{
+  state_t *probe = STATE_ALLOC (core_size);
+  state_t *entry;
+
+  probe->nitems = core_size;
+  memcpy (probe->items, core, core_size * sizeof (core[0]));
+  entry = hash_lookup (state_table, probe);
+  free (probe);
+  return entry;
+}
+
+/* All the decorated states, indexed by the state number.  */
+state_t **states = NULL;
+
+
+/*----------------------.
+| Free all the states.  |
+`----------------------*/
+
+void
+states_free (void)
+{
+  state_number_t i;
+  for (i = 0; i < nstates; ++i)
+    state_free (states[i]);
+  free (states);
+}