X-Git-Url: https://git.saurik.com/bison.git/blobdiff_plain/ceed8467b7db3615d3c9bfa9f3e5525d54c6a161..796d61fbdd7bd5db9947451a204c76b5d046b308:/src/LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index 401c11c0..5e8caef0 100644
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,117 +1,89 @@
 /* Generate the nondeterministic finite state machine for bison,
-   Copyright (C) 1984, 1986, 1989 Free Software Foundation, Inc.
+   Copyright 1984, 1986, 1989, 2000, 2001  Free Software Foundation, Inc.
 
-This file is part of Bison, the GNU Compiler Compiler.
+   This file is part of Bison, the GNU Compiler Compiler.
 
-Bison 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 2, or (at your option)
-any later version.
+   Bison 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 2, or (at your option)
+   any later version.
 
-Bison 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.
+   Bison 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 Bison; see the file COPYING.  If not, write to
-the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
-Boston, MA 02111-1307, USA.  */
+   You should have received a copy of the GNU General Public License
+   along with Bison; see the file COPYING.  If not, write to
+   the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+   Boston, MA 02111-1307, USA.  */
 
 
 /* See comments in state.h for the data structures that represent it.
    The entry point is generate_states.  */
 
 #include "system.h"
-#include "alloc.h"
+#include "getargs.h"
+#include "reader.h"
 #include "gram.h"
 #include "state.h"
 #include "complain.h"
-
-
-extern char *nullable;
-extern short *itemset;
-extern short *itemsetend;
-
+#include "closure.h"
+#include "LR0.h"
+#include "lalr.h"
+#include "reduce.h"
 
 int nstates;
 int final_state;
-core *first_state;
-shifts *first_shift;
-reductions *first_reduction;
-
-extern void generate_states PARAMS((void));
-
-static int get_state PARAMS((int));
-static core *new_state PARAMS((int));
-static void allocate_itemsets PARAMS((void));
-static void allocate_storage PARAMS((void));
-static void free_storage PARAMS((void));
-static void new_itemsets PARAMS((void));
-static void append_states PARAMS((void));
-static void initialize_states PARAMS((void));
-static void save_shifts PARAMS((void));
-static void save_reductions PARAMS((void));
-static void augment_automaton PARAMS((void));
-static void insert_start_shift PARAMS((void));
-extern void initialize_closure PARAMS((int));
-extern void closure PARAMS((short *, int));
-extern void finalize_closure PARAMS((void));
-
-static core *this_state;
-static core *last_state;
-static shifts *last_shift;
-static reductions *last_reduction;
+static state_t *first_state = NULL;
+
+static state_t *this_state = NULL;
+static state_t *last_state = NULL;
 
 static int nshifts;
-static short *shift_symbol;
+static short *shift_symbol = NULL;
 
-static short *redset;
-static short *shiftset;
+static short *redset = NULL;
+static short *shiftset = NULL;
 
-static short **kernel_base;
-static short **kernel_end;
-static short *kernel_items;
+static short **kernel_base = NULL;
+static int *kernel_size = NULL;
+static short *kernel_items = NULL;
 
 /* hash table for states, to recognize equivalent ones.  */
 
-#define	STATE_TABLE_SIZE	1009
-static core **state_table;
-
-
+#define	STATE_HASH_SIZE	1009
+static state_t **state_hash = NULL;
 
+
 static void
 allocate_itemsets (void)
 {
-  register short *itemp;
-  register int symbol;
-  register int i;
-  register int count;
-  register short *symbol_count;
-
-  count = 0;
-  symbol_count = NEW2(nsyms, short);
-
-  itemp = ritem;
-  symbol = *itemp++;
-  while (symbol)
-    {
-      if (symbol > 0)
-	{
-	  count++;
-	  symbol_count[symbol]++;
-	}
-      symbol = *itemp++;
-    }
-
-  /* see comments before new_itemsets.  All the vectors of items
-     live inside kernel_items.  The number of active items after
+  int i;
+
+  /* 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.  */
+  int count = 0;
+  short *symbol_count = XCALLOC (short, nsyms + nuseless_nonterminals);
+
+  for (i = 0; ritem[i]; ++i)
+    if (ritem[i] > 0)
+      {
+	count++;
+	symbol_count[ritem[i]]++;
+      }
+
+  /* See comments before new_itemsets.  All the vectors of items
+     live inside KERNEL_ITEMS.  The number of active items after
      some symbol cannot be more than the number of times that symbol
      appears as an item, which is symbol_count[symbol].
      We allocate that much space for each symbol.  */
 
-  kernel_base = NEW2(nsyms, short *);
-  kernel_items = NEW2(count, short);
+  kernel_base = XCALLOC (short *, nsyms);
+  if (count)
+    kernel_items = XCALLOC (short, count);
 
   count = 0;
   for (i = 0; i < nsyms; i++)
@@ -120,216 +92,150 @@ allocate_itemsets (void)
       count += symbol_count[i];
     }
 
-  shift_symbol = symbol_count;
-  kernel_end = NEW2(nsyms, short *);
+  free (symbol_count);
+  kernel_size = XCALLOC (int, nsyms);
 }
 
 
 static void
 allocate_storage (void)
 {
-  allocate_itemsets();
+  allocate_itemsets ();
 
-  shiftset = NEW2(nsyms, short);
-  redset = NEW2(nrules + 1, short);
-  state_table = NEW2(STATE_TABLE_SIZE, core *);
+  shiftset = XCALLOC (short, nsyms);
+  redset = XCALLOC (short, nrules + 1);
+  state_hash = XCALLOC (state_t *, STATE_HASH_SIZE);
 }
 
 
 static void
 free_storage (void)
 {
-  FREE(shift_symbol);
-  FREE(redset);
-  FREE(shiftset);
-  FREE(kernel_base);
-  FREE(kernel_end);
-  FREE(kernel_items);
-  FREE(state_table);
+  free (shift_symbol);
+  free (redset);
+  free (shiftset);
+  free (kernel_base);
+  free (kernel_size);
+  XFREE (kernel_items);
+  free (state_hash);
 }
 
 
 
-/* compute the nondeterministic finite state machine (see state.h for details)
-from the grammar.  */
-void
-generate_states (void)
-{
-  allocate_storage();
-  initialize_closure(nitems);
-  initialize_states();
-
-  while (this_state)
-    {
-      /* Set up ruleset and itemset for the transitions out of this state.
-         ruleset gets a 1 bit for each rule that could reduce now.
-	 itemset gets a vector of all the items that could be accepted next.  */
-      closure(this_state->items, this_state->nitems);
-      /* record the reductions allowed out of this state */
-      save_reductions();
-      /* find the itemsets of the states that shifts can reach */
-      new_itemsets();
-      /* find or create the core structures for those states */
-      append_states();
-
-      /* create the shifts structures for the shifts to those states,
-         now that the state numbers transitioning to are known */
-      if (nshifts > 0)
-        save_shifts();
-
-      /* states are queued when they are created; process them all */
-      this_state = this_state->next;
-    }
-
-  /* discard various storage */
-  finalize_closure();
-  free_storage();
-
-  /* set up initial and final states as parser wants them */
-  augment_automaton();
-}
-
 
+/*----------------------------------------------------------------.
+| Find which symbols can be shifted in the current state, 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.              |
+`----------------------------------------------------------------*/
 
-/* Find which symbols can be shifted in the current state,
-   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_end[symbol] points after the end of that vector.  */
 static void
 new_itemsets (void)
 {
-  register int i;
-  register int shiftcount;
-  register short *isp;
-  register short *ksp;
-  register int symbol;
+  int i;
 
-#ifdef	TRACE
-  fprintf(stderr, "Entering new_itemsets\n");
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering new_itemsets, state = %d\n",
+	     this_state->number);
 
   for (i = 0; i < nsyms; i++)
-    kernel_end[i] = NULL;
-
-  shiftcount = 0;
+    kernel_size[i] = 0;
 
-  isp = itemset;
+  shift_symbol = XCALLOC (short, nsyms);
+  nshifts = 0;
 
-  while (isp < itemsetend)
+  for (i = 0; i < nitemset; ++i)
     {
-      i = *isp++;
-      symbol = ritem[i];
+      int symbol = ritem[itemset[i]];
       if (symbol > 0)
 	{
-          ksp = kernel_end[symbol];
-
-          if (!ksp)
+	  if (!kernel_size[symbol])
 	    {
-	      shift_symbol[shiftcount++] = symbol;
-	      ksp = kernel_base[symbol];
+	      shift_symbol[nshifts] = symbol;
+	      nshifts++;
 	    }
 
-          *ksp++ = i + 1;
-          kernel_end[symbol] = ksp;
+	  kernel_base[symbol][kernel_size[symbol]] = itemset[i] + 1;
+	  kernel_size[symbol]++;
 	}
     }
-
-  nshifts = shiftcount;
 }
 
 
 
-/* Use the information computed by new_itemsets to find the state numbers
-   reached by each shift transition from the current state.
+/*-----------------------------------------------------------------.
+| Subroutine of get_state.  Create a new state for those items, if |
+| necessary.                                                       |
+`-----------------------------------------------------------------*/
 
-   shiftset is set up as a vector of state numbers of those states.  */
-static void
-append_states (void)
+static state_t *
+new_state (int symbol)
 {
-  register int i;
-  register int j;
-  register int symbol;
+  state_t *p;
 
-#ifdef	TRACE
-  fprintf(stderr, "Entering append_states\n");
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
+	     this_state->number, symbol, tags[symbol]);
 
-  /* first sort shift_symbol into increasing order */
+  if (nstates >= MAXSHORT)
+    fatal (_("too many states (max %d)"), MAXSHORT);
 
-  for (i = 1; i < nshifts; i++)
-    {
-      symbol = shift_symbol[i];
-      j = i;
-      while (j > 0 && shift_symbol[j - 1] > symbol)
-	{
-	  shift_symbol[j] = shift_symbol[j - 1];
-	  j--;
-	}
-      shift_symbol[j] = symbol;
-    }
+  p = STATE_ALLOC (kernel_size[symbol]);
+  p->accessing_symbol = symbol;
+  p->number = nstates;
+  p->nitems = kernel_size[symbol];
 
-  for (i = 0; i < nshifts; i++)
-    {
-      symbol = shift_symbol[i];
-      shiftset[i] = get_state(symbol);
-    }
-}
+  shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]);
+
+  last_state->next = p;
+  last_state = p;
+  nstates++;
 
+  return p;
+}
 
 
-/* find the state number for the state we would get to
-(from the current state) by shifting symbol.
-Create a new state if no equivalent one exists already.
-Used by append_states  */
+/*--------------------------------------------------------------.
+| Find the state number for the state we would get to (from the |
+| current state) by shifting symbol.  Create a new state if no  |
+| equivalent one exists already.  Used by append_states.        |
+`--------------------------------------------------------------*/
 
 static int
 get_state (int symbol)
 {
-  register int key;
-  register short *isp1;
-  register short *isp2;
-  register short *iend;
-  register core *sp;
-  register int found;
-
-  int n;
+  int key;
+  int i;
+  state_t *sp;
 
-#ifdef	TRACE
-  fprintf(stderr, "Entering get_state, symbol = %d\n", symbol);
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
+	     this_state->number, symbol, tags[symbol]);
 
-  isp1 = kernel_base[symbol];
-  iend = kernel_end[symbol];
-  n = iend - isp1;
-
-  /* add up the target state's active item numbers to get a hash key */
+  /* Add up the target state's active item numbers to get a hash key.
+     */
   key = 0;
-  while (isp1 < iend)
-    key += *isp1++;
-
-  key = key % STATE_TABLE_SIZE;
-
-  sp = state_table[key];
+  for (i = 0; i < kernel_size[symbol]; ++i)
+    key += kernel_base[symbol][i];
+  key = key % STATE_HASH_SIZE;
+  sp = state_hash[key];
 
   if (sp)
     {
-      found = 0;
+      int found = 0;
       while (!found)
 	{
-	  if (sp->nitems == n)
+	  if (sp->nitems == kernel_size[symbol])
 	    {
 	      found = 1;
-	      isp1 = kernel_base[symbol];
-	      isp2 = sp->items;
-
-	      while (found && isp1 < iend)
-		{
-		  if (*isp1++ != *isp2++)
-		    found = 0;
-		}
+	      for (i = 0; i < kernel_size[symbol]; ++i)
+		if (kernel_base[symbol][i] != sp->items[i])
+		  found = 0;
 	    }
 
 	  if (!found)
@@ -338,368 +244,368 @@ get_state (int symbol)
 		{
 		  sp = sp->link;
 		}
-	      else   /* bucket exhausted and no match */
+	      else		/* bucket exhausted and no match */
 		{
-		  sp = sp->link = new_state(symbol);
+		  sp = sp->link = new_state (symbol);
 		  found = 1;
 		}
 	    }
 	}
     }
-  else      /* bucket is empty */
+  else				/* bucket is empty */
     {
-      state_table[key] = sp = new_state(symbol);
+      state_hash[key] = sp = new_state (symbol);
     }
 
+  if (trace_flag)
+    fprintf (stderr, "Exiting get_state => %d\n", sp->number);
+
   return sp->number;
 }
 
+/*------------------------------------------------------------------.
+| Use the information computed by new_itemsets to find the state    |
+| numbers reached by each shift transition from the current state.  |
+|                                                                   |
+| shiftset is set up as a vector of state numbers of those states.  |
+`------------------------------------------------------------------*/
 
-
-/* subroutine of get_state.  create a new state for those items, if necessary.  */
-
-static core *
-new_state (int symbol)
+static void
+append_states (void)
 {
-  register int n;
-  register core *p;
-  register short *isp1;
-  register short *isp2;
-  register short *iend;
+  int i;
+  int j;
+  int symbol;
 
-#ifdef	TRACE
-  fprintf(stderr, "Entering new_state, symbol = %d\n", symbol);
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering append_states, state = %d\n",
+	     this_state->number);
 
-  if (nstates >= MAXSHORT)
-    fatal (_("too many states (max %d)"), MAXSHORT);
-
-  isp1 = kernel_base[symbol];
-  iend = kernel_end[symbol];
-  n = iend - isp1;
-
-  p = (core *) xmalloc((unsigned) (sizeof(core) + (n - 1) * sizeof(short)));
-  p->accessing_symbol = symbol;
-  p->number = nstates;
-  p->nitems = n;
-
-  isp2 = p->items;
-  while (isp1 < iend)
-    *isp2++ = *isp1++;
-
-  last_state->next = p;
-  last_state = p;
+  /* first sort shift_symbol into increasing order */
 
-  nstates++;
+  for (i = 1; i < nshifts; i++)
+    {
+      symbol = shift_symbol[i];
+      j = i;
+      while (j > 0 && shift_symbol[j - 1] > symbol)
+	{
+	  shift_symbol[j] = shift_symbol[j - 1];
+	  j--;
+	}
+      shift_symbol[j] = symbol;
+    }
 
-  return p;
+  for (i = 0; i < nshifts; i++)
+    shiftset[i] = get_state (shift_symbol[i]);
 }
 
 
 static void
-initialize_states (void)
+new_states (void)
 {
-  register core *p;
-/*  register unsigned *rp1; JF unused */
-/*  register unsigned *rp2; JF unused */
-/*  register unsigned *rend; JF unused */
-
-  p = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short)));
-  first_state = last_state = this_state = p;
+  first_state = last_state = this_state = STATE_ALLOC (0);
   nstates = 1;
 }
 
 
+/*------------------------------------------------------------.
+| Save the NSHIFTS of SHIFTSET into the current linked list.  |
+`------------------------------------------------------------*/
+
 static void
 save_shifts (void)
 {
-  register shifts *p;
-  register short *sp1;
-  register short *sp2;
-  register short *send;
+  shifts *p = shifts_new (nshifts);
+  shortcpy (p->shifts, shiftset, nshifts);
+  this_state->shifts = p;
+}
 
-  p = (shifts *) xmalloc((unsigned) (sizeof(shifts) +
-				     (nshifts - 1) * sizeof(short)));
 
-  p->number = this_state->number;
-  p->nshifts = nshifts;
+/*------------------------------------------------------------------.
+| Subroutine of augment_automaton.  Create the next-to-final state, |
+| to which a shift has already been made in the initial state.      |
+|                                                                   |
+| The task of this state consists in shifting (actually, it's a     |
+| goto, but shifts and gotos are both stored in SHIFTS) the start   |
+| symbols, hence the name.                                          |
+`------------------------------------------------------------------*/
 
-  sp1 = shiftset;
-  sp2 = p->shifts;
-  send = shiftset + nshifts;
+static void
+insert_start_shifting_state (void)
+{
+  state_t *statep;
+  shifts *sp;
 
-  while (sp1 < send)
-    *sp2++ = *sp1++;
+  statep = STATE_ALLOC (0);
+  statep->number = nstates++;
 
-  if (last_shift)
-    {
-      last_shift->next = p;
-      last_shift = p;
-    }
-  else
-    {
-      first_shift = p;
-      last_shift = p;
-    }
+  /* The distinctive feature of this state from the
+     eof_shifting_state, is that it is labeled as post-start-symbol
+     shifting.  I fail to understand why this state, and the
+     post-start-start can't be merged into one.  But it does fail if
+     you try. --akim */
+  statep->accessing_symbol = start_symbol;
+
+  last_state->next = statep;
+  last_state = statep;
+
+  /* Make a shift from this state to (what will be) the final state.  */
+  sp = shifts_new (1);
+  statep->shifts = sp;
+  sp->shifts[0] = nstates;
 }
 
 
+/*-----------------------------------------------------------------.
+| Subroutine of augment_automaton.  Create the final state, which  |
+| shifts `0', the end of file.  The initial state shifts the start |
+| symbol, and goes to here.                                        |
+`-----------------------------------------------------------------*/
 
-/* 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 (void)
+insert_eof_shifting_state (void)
 {
-  register short *isp;
-  register short *rp1;
-  register short *rp2;
-  register int item;
-  register int count;
-  register reductions *p;
-
-  short *rend;
+  state_t *statep;
+  shifts *sp;
 
-  /* find and count the active items that represent ends of rules */
+  /* Make the final state--the one that follows a shift from the
+     next-to-final state.
+     The symbol for that shift is 0 (end-of-file).  */
+  statep = STATE_ALLOC (0);
+  statep->number = nstates++;
 
-  count = 0;
-  for (isp = itemset; isp < itemsetend; isp++)
-    {
-      item = ritem[*isp];
-      if (item < 0)
-	{
-	  redset[count++] = -item;
-	}
-    }
+  last_state->next = statep;
+  last_state = statep;
 
-  /* make a reductions structure and copy the data into it.  */
+  /* Make the shift from the final state to the termination state.  */
+  sp = shifts_new (1);
+  statep->shifts = sp;
+  sp->shifts[0] = nstates;
+}
 
-  if (count)
-    {
-      p = (reductions *) xmalloc((unsigned) (sizeof(reductions) +
-					     (count - 1) * sizeof(short)));
 
-      p->number = this_state->number;
-      p->nreds = count;
+/*---------------------------------------------------------------.
+| Subroutine of augment_automaton.  Create the accepting state.  |
+`---------------------------------------------------------------*/
 
-      rp1 = redset;
-      rp2 = p->rules;
-      rend = rp1 + count;
+static void
+insert_accepting_state (void)
+{
+  state_t *statep;
 
-      while (rp1 < rend)
-	*rp2++ = *rp1++;
+   /* Note that the variable `final_state' refers to what we sometimes
+      call the termination state.  */
+  final_state = nstates;
 
-      if (last_reduction)
-	{
-	  last_reduction->next = p;
-	  last_reduction = p;
-	}
-      else
-	{
-	  first_reduction = p;
-	  last_reduction = p;
-	}
-    }
+  /* Make the termination state.  */
+  statep = STATE_ALLOC (0);
+  statep->number = nstates++;
+  last_state->next = statep;
+  last_state = statep;
 }
 
 
 
-/* Make sure that the initial state has a shift that accepts the
-grammar's start symbol and goes to the next-to-final state,
-which has a shift going to the final state, which has a shift
-to the termination state.
-Create such states and shifts if they don't happen to exist already.  */
+
+
+/*------------------------------------------------------------------.
+| Make sure that the initial state has a shift that accepts the     |
+| grammar's start symbol and goes to the next-to-final state, which |
+| has a shift going to the final state, which has a shift to the    |
+| termination state.  Create such states and shifts if they don't   |
+| happen to exist already.                                          |
+`------------------------------------------------------------------*/
+
 static void
 augment_automaton (void)
 {
-  register int i;
-  register int k;
-/*  register int found; JF unused */
-  register core *statep;
-  register shifts *sp;
-  register shifts *sp2;
-  register shifts *sp1 = NULL;
+  if (!first_state->shifts->nshifts)
+    {
+      /* The first state has no shifts.  Make one shift, from the
+	 initial state to the next-to-final state.  */
 
-  sp = first_shift;
+      shifts *sp = shifts_new (1);
+      first_state->shifts = sp;
+      sp->shifts[0] = nstates;
 
-  if (sp)
+      /* Create the next-to-final state, with shift to
+         what will be the final state.  */
+      insert_start_shifting_state ();
+    }
+  else
     {
-      if (sp->number == 0)
+      state_t *statep = first_state->next;
+      /* The states reached by shifts from FIRST_STATE are numbered
+	 1..(SP->NSHIFTS).  Look for one reached by START_SYMBOL.
+	 This is typical of `start: start ... ;': there is a state
+	 with the item `start: start . ...'.  We want to add a `shift
+	 on EOF to eof-shifting state here.  */
+      while (statep->accessing_symbol != start_symbol
+	     && statep->number < first_state->shifts->nshifts)
+	statep = statep->next;
+
+      if (statep->accessing_symbol == start_symbol)
 	{
-	  k = sp->nshifts;
-	  statep = first_state->next;
+	  /* We already have STATEP, a next-to-final state for `start:
+	     start . ...'.  Make sure it has a shift to what will be
+	     the final state.  */
+	  int i;
 
-	  /* The states reached by shifts from first_state are numbered 1...K.
-	     Look for one reached by start_symbol.  */
-	  while (statep->accessing_symbol < start_symbol
-		  && statep->number < k)
-	    statep = statep->next;
+	  /* Find the shift of the inital state that leads to STATEP.  */
+	  shifts *sp = statep->shifts;
 
-	  if (statep->accessing_symbol == start_symbol)
-	    {
-	      /* We already have a next-to-final state.
-		 Make sure it has a shift to what will be the final state.  */
-	      k = statep->number;
+	  shifts *sp1 = shifts_new (sp->nshifts + 1);
+	  statep->shifts = sp1;
+	  sp1->shifts[0] = nstates;
+	  for (i = sp->nshifts; i > 0; i--)
+	    sp1->shifts[i] = sp->shifts[i - 1];
 
-	      while (sp && sp->number < k)
-		{
-		  sp1 = sp;
-		  sp = sp->next;
-		}
+	  XFREE (sp);
 
-	      if (sp && sp->number == k)
-		{
-		  sp2 = (shifts *) xmalloc((unsigned) (sizeof(shifts)
-						       + sp->nshifts * sizeof(short)));
-		  sp2->number = k;
-		  sp2->nshifts = sp->nshifts + 1;
-		  sp2->shifts[0] = nstates;
-		  for (i = sp->nshifts; i > 0; i--)
-		    sp2->shifts[i] = sp->shifts[i - 1];
-
-		  /* Patch sp2 into the chain of shifts in place of sp,
-		     following sp1.  */
-		  sp2->next = sp->next;
-		  sp1->next = sp2;
-		  if (sp == last_shift)
-		    last_shift = sp2;
-		  FREE(sp);
-		}
-	      else
-		{
-		  sp2 = NEW(shifts);
-		  sp2->number = k;
-		  sp2->nshifts = 1;
-		  sp2->shifts[0] = nstates;
-
-		  /* Patch sp2 into the chain of shifts between sp1 and sp.  */
-		  sp2->next = sp;
-		  sp1->next = sp2;
-		  if (sp == 0)
-		    last_shift = sp2;
-		}
-	    }
-	  else
-	    {
-	      /* There is no next-to-final state as yet.  */
-	      /* Add one more shift in first_shift,
-		 going to the next-to-final state (yet to be made).  */
-	      sp = first_shift;
-
-	      sp2 = (shifts *) xmalloc(sizeof(shifts)
-					 + sp->nshifts * sizeof(short));
-	      sp2->nshifts = sp->nshifts + 1;
-
-	      /* Stick this shift into the vector at the proper place.  */
-	      statep = first_state->next;
-	      for (k = 0, i = 0; i < sp->nshifts; k++, i++)
-		{
-		  if (statep->accessing_symbol > start_symbol && i == k)
-		    sp2->shifts[k++] = nstates;
-		  sp2->shifts[k] = sp->shifts[i];
-		  statep = statep->next;
-		}
-	      if (i == k)
-		sp2->shifts[k++] = nstates;
-
-	      /* Patch sp2 into the chain of shifts
-		 in place of sp, at the beginning.  */
-	      sp2->next = sp->next;
-	      first_shift = sp2;
-	      if (last_shift == sp)
-		last_shift = sp2;
-
-	      FREE(sp);
-
-	      /* Create the next-to-final state, with shift to
-		 what will be the final state.  */
-	      insert_start_shift();
-	    }
+	  insert_eof_shifting_state ();
 	}
       else
 	{
-	  /* The initial state didn't even have any shifts.
-	     Give it one shift, to the next-to-final state.  */
-	  sp = NEW(shifts);
-	  sp->nshifts = 1;
-	  sp->shifts[0] = nstates;
-
-	  /* Patch sp into the chain of shifts at the beginning.  */
-	  sp->next = first_shift;
-	  first_shift = sp;
-
-	  /* Create the next-to-final state, with shift to
-	     what will be the final state.  */
-	  insert_start_shift();
+	  /* There is no state for `start: start . ...'. */
+	  int i, k;
+	  shifts *sp = first_state->shifts;
+	  shifts *sp1 = NULL;
+
+	  /* Add one more shift to the initial state, going to the
+	     next-to-final state (yet to be made).  */
+	  sp1 = shifts_new (sp->nshifts + 1);
+	  first_state->shifts = sp1;
+	  /* Stick this shift into the vector at the proper place.  */
+	  statep = first_state->next;
+	  for (k = 0, i = 0; i < sp->nshifts; k++, i++)
+	    {
+	      if (statep->accessing_symbol > start_symbol && i == k)
+		sp1->shifts[k++] = nstates;
+	      sp1->shifts[k] = sp->shifts[i];
+	      statep = statep->next;
+	    }
+	  if (i == k)
+	    sp1->shifts[k++] = nstates;
+
+	  XFREE (sp);
+
+	  /* Create the next-to-final state, with shift to what will
+	     be the final state.  Corresponds to `start: start . ...'.  */
+	  insert_start_shifting_state ();
 	}
     }
-  else
-    {
-      /* There are no shifts for any state.
-	 Make one shift, from the initial state to the next-to-final state.  */
 
-      sp = NEW(shifts);
-      sp->nshifts = 1;
-      sp->shifts[0] = nstates;
+  insert_accepting_state ();
+}
 
-      /* Initialize the chain of shifts with sp.  */
-      first_shift = sp;
-      last_shift = sp;
 
-      /* Create the next-to-final state, with shift to
-	 what will be the final state.  */
-      insert_start_shift();
-    }
+/*----------------------------------------------------------------.
+| 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.                                      |
+`----------------------------------------------------------------*/
 
-  /* Make the final state--the one that follows a shift from the
-     next-to-final state.
-     The symbol for that shift is 0 (end-of-file).  */
-  statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short)));
-  statep->number = nstates;
-  last_state->next = statep;
-  last_state = statep;
+static void
+save_reductions (void)
+{
+  int count;
+  int i;
 
-  /* Make the shift from the final state to the termination state.  */
-  sp = NEW(shifts);
-  sp->number = nstates++;
-  sp->nshifts = 1;
-  sp->shifts[0] = nstates;
-  last_shift->next = sp;
-  last_shift = sp;
+  /* Find and count the active items that represent ends of rules. */
 
-  /* Note that the variable `final_state' refers to what we sometimes call
-     the termination state.  */
-  final_state = nstates;
+  count = 0;
+  for (i = 0; i < nitemset; ++i)
+    {
+      int item = ritem[itemset[i]];
+      if (item < 0)
+	redset[count++] = -item;
+    }
 
-  /* Make the termination state.  */
-  statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short)));
-  statep->number = nstates++;
-  last_state->next = statep;
-  last_state = statep;
+  /* Make a reductions structure and copy the data into it.  */
+
+  if (count)
+    {
+      reductions *p = REDUCTIONS_ALLOC (count);
+      p->nreds = count;
+      shortcpy (p->rules, redset, count);
+
+      this_state->reductions = p;
+    }
 }
 
+
+/*--------------------.
+| Build STATE_TABLE.  |
+`--------------------*/
 
-/* subroutine of augment_automaton.
-   Create the next-to-final state, to which a shift has already been made in
-   the initial state.  */
 static void
-insert_start_shift (void)
+set_state_table (void)
 {
-  register core *statep;
-  register shifts *sp;
+  /* NSTATES + 1 because lookahead for the pseudo state number NSTATES
+     might be used (see conflicts.c).  It is too opaque for me to
+     provide a probably less hacky implementation. --akim */
+  state_table = XCALLOC (state_t *, nstates + 1);
+
+  {
+    state_t *sp;
+    for (sp = first_state; sp; sp = sp->next)
+      state_table[sp->number] = sp;
+  }
+
+  /* Pessimization, but simplification of the code: make sure all the
+     states have a shifts, even if reduced to 0 shifts.  */
+  {
+    int i;
+    for (i = 0; i < nstates; i++)
+      if (!state_table[i]->shifts)
+	state_table[i]->shifts = shifts_new (0);
+  }
+}
 
-  statep = (core *) xmalloc((unsigned) (sizeof(core) - sizeof(short)));
-  statep->number = nstates;
-  statep->accessing_symbol = start_symbol;
+/*-------------------------------------------------------------------.
+| Compute the nondeterministic finite state machine (see state.h for |
+| details) from the grammar.                                         |
+`-------------------------------------------------------------------*/
 
-  last_state->next = statep;
-  last_state = statep;
+void
+generate_states (void)
+{
+  allocate_storage ();
+  new_closure (nitems);
+  new_states ();
 
-  /* Make a shift from this state to (what will be) the final state.  */
-  sp = NEW(shifts);
-  sp->number = nstates++;
-  sp->nshifts = 1;
-  sp->shifts[0] = nstates;
+  while (this_state)
+    {
+      if (trace_flag)
+	fprintf (stderr, "Processing state %d (reached by %s)\n",
+		 this_state->number, tags[this_state->accessing_symbol]);
+      /* Set up ruleset and itemset for the transitions out of this
+         state.  ruleset gets a 1 bit for each rule that could reduce
+         now.  itemset gets a vector of all the items that could be
+         accepted next.  */
+      closure (this_state->items, this_state->nitems);
+      /* record the reductions allowed out of this state */
+      save_reductions ();
+      /* find the itemsets of the states that shifts can reach */
+      new_itemsets ();
+      /* find or create the core structures for those states */
+      append_states ();
+
+      /* create the shifts structures for the shifts to those states,
+         now that the state numbers transitioning to are known */
+      save_shifts ();
+
+      /* states are queued when they are created; process them all */
+      this_state = this_state->next;
+    }
+
+  /* discard various storage */
+  free_closure ();
+  free_storage ();
+
+  /* set up initial and final states as parser wants them */
+  augment_automaton ();
 
-  last_shift->next = sp;
-  last_shift = sp;
+  /* Set up STATE_TABLE. */
+  set_state_table ();
 }