Add native Windows binary for bison.

bison/src/bison/2.4.1/bison-2.4.1-src/src/LR0.c

+/* Generate the nondeterministic finite state machine for Bison.
+
+   Copyright (C) 1984, 1986, 1989, 2000, 2001, 2002, 2004, 2005, 2006, 2007
+   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/>.  */
+
+
+/* See comments in state.h for the data structures that represent it.
+   The entry point is generate_states.  */
+
+#include <config.h>
+#include "system.h"
+
+#include <bitset.h>
+#include <quotearg.h>
+
+#include "LR0.h"
+#include "closure.h"
+#include "complain.h"
+#include "getargs.h"
+#include "gram.h"
+#include "gram.h"
+#include "lalr.h"
+#include "reader.h"
+#include "reduce.h"
+#include "state.h"
+#include "symtab.h"
+
+typedef struct state_list
+{
+  struct state_list *next;
+  state *state;
+} state_list;
+
+static state_list *first_state = NULL;
+static state_list *last_state = NULL;
+
+
+/*------------------------------------------------------------------.
+| A state was just discovered from another state.  Queue it for     |
+| later examination, in order to find its transitions.  Return it.  |
+`------------------------------------------------------------------*/
+
+static state *
+state_list_append (symbol_number sym, size_t core_size, item_number *core)
+{
+  state_list *node = xmalloc (sizeof *node);
+  state *s = state_new (sym, core_size, core);
+
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "state_list_append (state = %d, symbol = %d (%s))\n",
+             nstates, sym, symbols[sym]->tag);
+
+  node->next = NULL;
+  node->state = s;
+
+  if (!first_state)
+    first_state = node;
+  if (last_state)
+    last_state->next = node;
+  last_state = node;
+
+  return s;
+}
+
+static int nshifts;
+static symbol_number *shift_symbol;
+
+static rule **redset;
+static state **shiftset;
+
+static item_number **kernel_base;
+static int *kernel_size;
+static item_number *kernel_items;
+
+
+static void
+allocate_itemsets (void)
+{
+  symbol_number i;
+  rule_number r;
+  item_number *rhsp;
+
+  /* Count the number of occurrences of all the symbols in RITEMS.
+     Note that useless productions (hence useless nonterminals) are
+     browsed too, hence we need to allocate room for _all_ the
+     symbols.  */
+  size_t count = 0;
+  size_t *symbol_count = xcalloc (nsyms + nuseless_nonterminals,
+                                  sizeof *symbol_count);
+
+  for (r = 0; r < nrules; ++r)
+    for (rhsp = rules[r].rhs; *rhsp >= 0; ++rhsp)
+      {
+        count++;
+        symbol_count[*rhsp]++;
+      }
+
+  /* See comments before new_itemsets.  All the vectors of items
+     live inside KERNEL_ITEMS.  The number of active items after
+     some symbol S cannot be more than the number of times that S
+     appears as an item, which is SYMBOL_COUNT[S].
+     We allocate that much space for each symbol.  */
+
+  kernel_base = xnmalloc (nsyms, sizeof *kernel_base);
+  kernel_items = xnmalloc (count, sizeof *kernel_items);
+
+  count = 0;
+  for (i = 0; i < nsyms; i++)
+    {
+      kernel_base[i] = kernel_items + count;
+      count += symbol_count[i];
+    }
+
+  free (symbol_count);
+  kernel_size = xnmalloc (nsyms, sizeof *kernel_size);
+}
+
+
+static void
+allocate_storage (void)
+{
+  allocate_itemsets ();
+
+  shiftset = xnmalloc (nsyms, sizeof *shiftset);
+  redset = xnmalloc (nrules, sizeof *redset);
+  state_hash_new ();
+  shift_symbol = xnmalloc (nsyms, sizeof *shift_symbol);
+}
+
+
+static void
+free_storage (void)
+{
+  free (shift_symbol);
+  free (redset);
+  free (shiftset);
+  free (kernel_base);
+  free (kernel_size);
+  free (kernel_items);
+  state_hash_free ();
+}
+
+
+
+
+/*---------------------------------------------------------------.
+| Find which symbols can be shifted in S, and for each one       |
+| record which items would be active after that shift.  Uses the |
+| contents of itemset.                                           |
+|                                                                |
+| shift_symbol is set to a vector of the symbols that can be     |
+| shifted.  For each symbol in the grammar, kernel_base[symbol]  |
+| points to a vector of item numbers activated if that symbol is |
+| shifted, and kernel_size[symbol] is their numbers.             |
+|                                                                |
+| itemset is sorted on item index in ritem, which is sorted on   |
+| rule number.  Compute each kernel_base[symbol] with the same   |
+| sort.                                                          |
+`---------------------------------------------------------------*/
+
+static void
+new_itemsets (state *s)
+{
+  size_t i;
+
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "Entering new_itemsets, state = %d\n", s->number);
+
+  memset (kernel_size, 0, nsyms * sizeof *kernel_size);
+
+  nshifts = 0;
+
+  for (i = 0; i < nitemset; ++i)
+    if (item_number_is_symbol_number (ritem[itemset[i]]))
+      {
+        symbol_number sym = item_number_as_symbol_number (ritem[itemset[i]]);
+        if (!kernel_size[sym])
+          {
+            shift_symbol[nshifts] = sym;
+            nshifts++;
+          }
+
+        kernel_base[sym][kernel_size[sym]] = itemset[i] + 1;
+        kernel_size[sym]++;
+      }
+}
+
+
+
+/*--------------------------------------------------------------.
+| Find the state we would get to (from the current state) by    |
+| shifting SYM.  Create a new state if no equivalent one exists |
+| already.  Used by append_states.                              |
+`--------------------------------------------------------------*/
+
+static state *
+get_state (symbol_number sym, size_t core_size, item_number *core)
+{
+  state *s;
+
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "Entering get_state, symbol = %d (%s)\n",
+             sym, symbols[sym]->tag);
+
+  s = state_hash_lookup (core_size, core);
+  if (!s)
+    s = state_list_append (sym, core_size, core);
+
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "Exiting get_state => %d\n", s->number);
+
+  return s;
+}
+
+/*---------------------------------------------------------------.
+| Use the information computed by new_itemsets to find the state |
+| numbers reached by each shift transition from S.               |
+|                                                                |
+| SHIFTSET is set up as a vector of those states.                |
+`---------------------------------------------------------------*/
+
+static void
+append_states (state *s)
+{
+  int i;
+
+  if (trace_flag & trace_automaton)
+    fprintf (stderr, "Entering append_states, state = %d\n", s->number);
+
+  /* First sort shift_symbol into increasing order.  */
+
+  for (i = 1; i < nshifts; i++)
+    {
+      symbol_number sym = shift_symbol[i];
+      int j;
+      for (j = i; 0 < j && sym < shift_symbol[j - 1]; j--)
+        shift_symbol[j] = shift_symbol[j - 1];
+      shift_symbol[j] = sym;
+    }
+
+  for (i = 0; i < nshifts; i++)
+    {
+      symbol_number sym = shift_symbol[i];
+      shiftset[i] = get_state (sym, kernel_size[sym], kernel_base[sym]);
+    }
+}
+
+
+/*----------------------------------------------------------------.
+| Find which rules can be used for reduction transitions from the |
+| current state and make a reductions structure for the state to  |
+| record their rule numbers.                                      |
+`----------------------------------------------------------------*/
+
+static void
+save_reductions (state *s)
+{
+  int count = 0;
+  size_t i;
+
+  /* Find and count the active items that represent ends of rules. */
+  for (i = 0; i < nitemset; ++i)
+    {
+      item_number item = ritem[itemset[i]];
+      if (item_number_is_rule_number (item))
+        {
+          rule_number r = item_number_as_rule_number (item);
+          redset[count++] = &rules[r];
+          if (r == 0)
+            {
+              /* This is "reduce 0", i.e., accept. */
+              aver (!final_state);
+              final_state = s;
+            }
+        }
+    }
+
+  /* Make a reductions structure and copy the data into it.  */
+  state_reductions_set (s, count, redset);
+}
+
+
+/*---------------.
+| Build STATES.  |
+`---------------*/
+
+static void
+set_states (void)
+{
+  states = xcalloc (nstates, sizeof *states);
+
+  while (first_state)
+    {
+      state_list *this = first_state;
+
+      /* Pessimization, but simplification of the code: make sure all
+         the states have valid transitions and reductions members,
+         even if reduced to 0.  It is too soon for errs, which are
+         computed later, but set_conflicts.  */
+      state *s = this->state;
+      if (!s->transitions)
+        state_transitions_set (s, 0, 0);
+      if (!s->reductions)
+        state_reductions_set (s, 0, 0);
+
+      states[s->number] = s;
+
+      first_state = this->next;
+      free (this);
+    }
+  first_state = NULL;
+  last_state = NULL;
+}
+
+
+/*-------------------------------------------------------------------.
+| Compute the nondeterministic finite state machine (see state.h for |
+| details) from the grammar.                                         |
+`-------------------------------------------------------------------*/
+
+void
+generate_states (void)
+{
+  item_number initial_core = 0;
+  state_list *list = NULL;
+  allocate_storage ();
+  new_closure (nritems);
+
+  /* Create the initial state.  The 0 at the lhs is the index of the
+     item of this initial rule.  */
+  state_list_append (0, 1, &initial_core);
+
+  /* States are queued when they are created; process them all.  */
+  for (list = first_state; list; list = list->next)
+    {
+      state *s = list->state;
+      if (trace_flag & trace_automaton)
+        fprintf (stderr, "Processing state %d (reached by %s)\n",
+                 s->number,
+                 symbols[s->accessing_symbol]->tag);
+      /* Set up itemset for the transitions out of this state.  itemset gets a
+         vector of all the items that could be accepted next.  */
+      closure (s->items, s->nitems);
+      /* Record the reductions allowed out of this state.  */
+      save_reductions (s);
+      /* Find the itemsets of the states that shifts can reach.  */
+      new_itemsets (s);
+      /* Find or create the core structures for those states.  */
+      append_states (s);
+
+      /* Create the shifts structures for the shifts to those states,
+         now that the state numbers transitioning to are known.  */
+      state_transitions_set (s, nshifts, shiftset);
+    }
+
+  /* discard various storage */
+  free_closure ();
+  free_storage ();
+
+  /* Set up STATES. */
+  set_states ();
+}