* src/closure.c (firsts): Now, also a bitset.

[bison.git] / src / LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index db42fe30a8c913961f45b7005de73abee8f87af1..6a911f240f47fe0bc569729854dd6c9e820aa4dc 100644 (file)
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -1,5 +1,5 @@
 /* Generate the nondeterministic finite state machine for bison,
 /* Generate the nondeterministic finite state machine for bison,

-   Copyright 1984, 1986, 1989, 2000 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.
 


@@ -23,23 +23,30 @@
    The entry point is generate_states.  */
 
 #include "system.h"
    The entry point is generate_states.  */
 
 #include "system.h"

+#include "symtab.h"
+#include "getargs.h"
+#include "reader.h"

 #include "gram.h"
 #include "state.h"
 #include "complain.h"
 #include "closure.h"
 #include "LR0.h"
 #include "gram.h"
 #include "state.h"
 #include "complain.h"
 #include "closure.h"
 #include "LR0.h"

-
+#include "lalr.h"
+#include "reduce.h"

 
 int nstates;
 
 int nstates;

-int final_state;
-core *first_state = NULL;
-shifts *first_shift = NULL;
-reductions *first_reduction = NULL;
+/* Initialize the final state to -1, otherwise, it might be set to 0
+   by default, and since we don't compute the reductions of the final
+   state, we end up not computing the reductions of the initial state,
+   which is of course needed.
+
+   FINAL_STATE is properly set by new_state when it recognizes the
+   accessing symbol: EOF.  */
+int final_state = -1;
+static state_t *first_state = NULL;

 
 

-static core *this_state = NULL;
-static core *last_state = NULL;
-static shifts *last_shift = NULL;
-static reductions *last_reduction = NULL;
+static state_t *this_state = NULL;
+static state_t *last_state = NULL;

 
 static int nshifts;
 static short *shift_symbol = NULL;
 
 static int nshifts;
 static short *shift_symbol = NULL;


@@ -48,38 +55,33 @@ static short *redset = NULL;
 static short *shiftset = NULL;
 
 static short **kernel_base = NULL;
 static short *shiftset = NULL;
 
 static short **kernel_base = NULL;

-static short **kernel_end = NULL;
+static int *kernel_size = NULL;

 static short *kernel_items = NULL;
 
 /* hash table for states, to recognize equivalent ones.  */
 
 static short *kernel_items = NULL;
 
 /* hash table for states, to recognize equivalent ones.  */
 

-#define        STATE_TABLE_SIZE        1009
-static core **state_table = NULL;
+#define        STATE_HASH_SIZE 1009
+static state_t **state_hash = NULL;

 
 \f
 static void
 allocate_itemsets (void)
 {
 
 \f
 static void
 allocate_itemsets (void)
 {

-  short *itemp = NULL;
-  int symbol;

   int i;
   int i;

-  int count;
-  short *symbol_count = NULL;

 
 

-  count = 0;
-  symbol_count = XCALLOC (short, nsyms);
+  /* 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);

 
 

-  itemp = ritem;
-  symbol = *itemp++;
-  while (symbol)
-    {
-      if (symbol > 0)
-       {
-         count++;
-         symbol_count[symbol]++;
-       }
-      symbol = *itemp++;
-    }
+  for (i = 0; i < nritems; ++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
 
   /* See comments before new_itemsets.  All the vectors of items
      live inside KERNEL_ITEMS.  The number of active items after


@@ -98,8 +100,8 @@ allocate_itemsets (void)
       count += symbol_count[i];
     }
 
       count += symbol_count[i];
     }
 

-  shift_symbol = symbol_count;
-  kernel_end = XCALLOC (short *, nsyms);
+  free (symbol_count);
+  kernel_size = XCALLOC (int, nsyms);

 }
 
 
 }
 
 


@@ -110,20 +112,21 @@ allocate_storage (void)
 
   shiftset = XCALLOC (short, nsyms);
   redset = XCALLOC (short, nrules + 1);
 
   shiftset = XCALLOC (short, nsyms);
   redset = XCALLOC (short, nrules + 1);

-  state_table = XCALLOC (core *, STATE_TABLE_SIZE);
+  state_hash = XCALLOC (state_t *, STATE_HASH_SIZE);
+  shift_symbol = XCALLOC (short, nsyms);

 }
 
 
 static void
 free_storage (void)
 {
 }
 
 
 static void
 free_storage (void)
 {

-  XFREE (shift_symbol);
-  XFREE (redset);
-  XFREE (shiftset);
-  XFREE (kernel_base);
-  XFREE (kernel_end);
+  free (shift_symbol);
+  free (redset);
+  free (shiftset);
+  free (kernel_base);
+  free (kernel_size);

   XFREE (kernel_items);
   XFREE (kernel_items);

-  XFREE (state_table);
+  free (state_hash);

 }
 
 
 }
 
 


@@ -137,51 +140,38 @@ free_storage (void)
 | 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  |
 | 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.                                                         |
+| shifted, and kernel_size[symbol] is their numbers.              |

 `----------------------------------------------------------------*/
 
 static void
 new_itemsets (void)
 {
   int i;
 `----------------------------------------------------------------*/
 
 static void
 new_itemsets (void)
 {
   int i;

-  int shiftcount;
-  short *isp;
-  short *ksp;
-  int symbol;

 
 

-#if TRACE
-  fprintf (stderr, "Entering new_itemsets, state = %d\n",
-          this_state->number);
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering new_itemsets, state = %d\n",
+            this_state->number);

 
   for (i = 0; i < nsyms; i++)
 
   for (i = 0; i < nsyms; i++)

-    kernel_end[i] = NULL;
+    kernel_size[i] = 0;

 
 

-  shiftcount = 0;
+  nshifts = 0;

 
 

-  isp = itemset;
-
-  while (isp < itemsetend)
+  for (i = 0; i < nitemset; ++i)

     {
     {

-      i = *isp++;
-      symbol = ritem[i];
-      if (symbol > 0)
+      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;

 }
 
 
 }
 
 


@@ -191,34 +181,33 @@ new_itemsets (void)
 | necessary.                                                       |
 `-----------------------------------------------------------------*/
 
 | necessary.                                                       |
 `-----------------------------------------------------------------*/
 

-static core *
+static state_t *

 new_state (int symbol)
 {
 new_state (int symbol)
 {

-  int n;
-  core *p;
+  state_t *p;

 
 

-#if TRACE
-  fprintf (stderr, "Entering new_state, symbol = %d, state = %d\n",
-          symbol, nstates);
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering new_state, state = %d, symbol = %d (%s)\n",
+            this_state->number, symbol, symbols[symbol]->tag);

 
   if (nstates >= MAXSHORT)
     fatal (_("too many states (max %d)"), MAXSHORT);
 
 
   if (nstates >= MAXSHORT)
     fatal (_("too many states (max %d)"), MAXSHORT);
 

-  n = kernel_end[symbol] - kernel_base[symbol];
-
-  p = CORE_ALLOC (n);
+  p = STATE_ALLOC (kernel_size[symbol]);

   p->accessing_symbol = symbol;
   p->number = nstates;
   p->accessing_symbol = symbol;
   p->number = nstates;

-  p->nitems = n;
+  p->nitems = kernel_size[symbol];

 
 

-  shortcpy (p->items, kernel_base[symbol], n);
+  shortcpy (p->items, kernel_base[symbol], kernel_size[symbol]);

 
   last_state->next = p;
   last_state = p;
 
   last_state->next = p;
   last_state = p;

-

   nstates++;
 
   nstates++;
 

+  /* If this is the eoftoken, then this is the final state. */
+  if (symbol == 0)
+    final_state = p->number;
+

   return p;
 }
 
   return p;
 }
 


@@ -226,54 +215,39 @@ new_state (int symbol)
 /*--------------------------------------------------------------.
 | Find the state number for the state we would get to (from the |
 | current state) by shifting symbol.  Create a new state if no  |
 /*--------------------------------------------------------------.
 | 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.         |
+| equivalent one exists already.  Used by append_states.        |

 `--------------------------------------------------------------*/
 
 static int
 get_state (int symbol)
 {
   int key;
 `--------------------------------------------------------------*/
 
 static int
 get_state (int symbol)
 {
   int key;

-  short *isp1;
-  short *isp2;
-  short *iend;
-  core *sp;
-  int found;
-
-  int n;
-
-#if TRACE
-  fprintf (stderr, "Entering get_state, symbol = %d\n", symbol);
-#endif
+  int i;
+  state_t *sp;

 
 

-  isp1 = kernel_base[symbol];
-  iend = kernel_end[symbol];
-  n = iend - isp1;
+  if (trace_flag)
+    fprintf (stderr, "Entering get_state, state = %d, symbol = %d (%s)\n",
+            this_state->number, symbol, symbols[symbol]->tag);

 
 

-  /* 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;
   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)
     {
 
   if (sp)
     {

-      found = 0;
+      int found = 0;

       while (!found)
        {
       while (!found)
        {

-         if (sp->nitems == n)
+         if (sp->nitems == kernel_size[symbol])

            {
              found = 1;
            {
              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)
            }
 
          if (!found)


@@ -292,9 +266,12 @@ get_state (int symbol)
     }
   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;
 }
 
   return sp->number;
 }
 


@@ -312,9 +289,9 @@ append_states (void)
   int j;
   int symbol;
 
   int j;
   int symbol;
 

-#if TRACE
-  fprintf (stderr, "Entering append_states\n");
-#endif
+  if (trace_flag)
+    fprintf (stderr, "Entering append_states, state = %d\n",
+            this_state->number);

 
   /* first sort shift_symbol into increasing order */
 
 
   /* first sort shift_symbol into increasing order */
 


@@ -331,250 +308,28 @@ append_states (void)
     }
 
   for (i = 0; i < nshifts; i++)
     }
 
   for (i = 0; i < nshifts; i++)

-    {
-      symbol = shift_symbol[i];
-      shiftset[i] = get_state (symbol);
-    }
+    shiftset[i] = get_state (shift_symbol[i]);

 }
 
 
 static void
 new_states (void)
 {
 }
 
 
 static void
 new_states (void)
 {

-  core *p;
-
-  p = CORE_ALLOC (0);
-  first_state = last_state = this_state = p;
+  first_state = last_state = this_state = STATE_ALLOC (0);

   nstates = 1;
 }
 
 
   nstates = 1;
 }
 
 

+/*------------------------------------------------------------.
+| Save the NSHIFTS of SHIFTSET into the current linked list.  |
+`------------------------------------------------------------*/
+

 static void
 save_shifts (void)
 {
 static void
 save_shifts (void)
 {

-  shifts *p;
-
-  p = SHIFTS_ALLOC (nshifts);
-
-  p->number = this_state->number;
-  p->nshifts = nshifts;
-
+  shifts *p = shifts_new (nshifts);

   shortcpy (p->shifts, shiftset, nshifts);
   shortcpy (p->shifts, shiftset, nshifts);

-
-  if (last_shift)
-    {
-      last_shift->next = p;
-      last_shift = p;
-    }
-  else
-    {
-      first_shift = p;
-      last_shift = p;
-    }
-}
-
-
-/*------------------------------------------------------------------.
-| 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)
-{
-  core *statep;
-  shifts *sp;
-
-  statep = CORE_ALLOC (0);
-  statep->number = nstates;
-  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_ALLOC (1);
-  sp->number = nstates++;
-  sp->nshifts = 1;
-  sp->shifts[0] = nstates;
-
-  last_shift->next = sp;
-  last_shift = sp;
-}
-
-
-/*------------------------------------------------------------------.
-| 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)
-{
-  int i;
-  int k;
-  core *statep;
-  shifts *sp;
-  shifts *sp2;
-  shifts *sp1 = NULL;
-
-  sp = first_shift;
-
-  if (sp)
-    {
-      if (sp->number == 0)
-       {
-         k = sp->nshifts;
-         statep = first_state->next;
-
-         /* 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;
-
-         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;
-
-             while (sp && sp->number < k)
-               {
-                 sp1 = sp;
-                 sp = sp->next;
-               }
-
-             if (sp && sp->number == k)
-               {
-                 sp2 = SHIFTS_ALLOC (sp->nshifts + 1);
-                 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;
-                 XFREE (sp);
-               }
-             else
-               {
-                 sp2 = SHIFTS_ALLOC (1);
-                 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_ALLOC (sp->nshifts + 1);
-             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;
-
-             XFREE (sp);
-
-             /* Create the next-to-final state, with shift to
-                what will be the final state.  */
-             insert_start_shift ();
-           }
-       }
-      else
-       {
-         /* The initial state didn't even have any shifts.
-            Give it one shift, to the next-to-final state.  */
-         sp = SHIFTS_ALLOC (1);
-         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 ();
-       }
-    }
-  else
-    {
-      /* There are no shifts for any state.
-         Make one shift, from the initial state to the next-to-final state.  */
-
-      sp = SHIFTS_ALLOC (1);
-      sp->nshifts = 1;
-      sp->shifts[0] = nstates;
-
-      /* 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 ();
-    }
-
-  /* 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_ALLOC (0);
-  statep->number = nstates;
-  last_state->next = statep;
-  last_state = statep;
-
-  /* Make the shift from the final state to the termination state.  */
-  sp = SHIFTS_ALLOC (1);
-  sp->number = nstates++;
-  sp->nshifts = 1;
-  sp->shifts[0] = nstates;
-  last_shift->next = sp;
-  last_shift = sp;
-
-  /* Note that the variable `final_state' refers to what we sometimes call
-     the termination state.  */
-  final_state = nstates;
-
-  /* Make the termination state.  */
-  statep = CORE_ALLOC (0);
-  statep->number = nstates++;
-  last_state->next = statep;
-  last_state = statep;
+  this_state->shifts = p;

 }
 
 
 }
 
 


@@ -587,48 +342,54 @@ augment_automaton (void)
 static void
 save_reductions (void)
 {
 static void
 save_reductions (void)
 {

-  short *isp;
-  int item;
-  int count;
-  reductions *p;
+  int count = 0;
+  int i;

 
 

-  short *rend;
+  /* If this is the final state, we want it to have no reductions at
+     all, although it has one for `START_SYMBOL EOF .'.  */
+  if (this_state->number == final_state)
+    return;

 
   /* Find and count the active items that represent ends of rules. */
 
   /* Find and count the active items that represent ends of rules. */

-
-  count = 0;
-  for (isp = itemset; isp < itemsetend; isp++)
+  for (i = 0; i < nitemset; ++i)

     {
     {

-      item = ritem[*isp];
+      int item = ritem[itemset[i]];

       if (item < 0)
        redset[count++] = -item;
     }
 
   /* Make a reductions structure and copy the data into it.  */
       if (item < 0)
        redset[count++] = -item;
     }
 
   /* Make a reductions structure and copy the data into it.  */

+  this_state->reductions = reductions_new (count);
+  shortcpy (this_state->reductions->rules, redset, count);
+}

 
 

-  if (count)
-    {
-      p = REDUCTIONS_ALLOC (count);
-
-      p->number = this_state->number;
-      p->nreds = count;
+\f
+/*---------------.
+| Build STATES.  |
+`---------------*/

 
 

-      shortcpy (p->rules, redset, count);
+static void
+set_states (void)
+{
+  state_t *sp;
+  states = XCALLOC (state_t *, nstates);

 
 

-      if (last_reduction)
-       {
-         last_reduction->next = p;
-         last_reduction = p;
-       }
-      else
-       {
-         first_reduction = p;
-         last_reduction = p;
-       }
+  for (sp = first_state; sp; sp = sp->next)
+    {
+      /* Pessimization, but simplification of the code: make sure all
+        the states have a shifts, errs, and reductions, even if
+        reduced to 0.  */
+      if (!sp->shifts)
+       sp->shifts = shifts_new (0);
+      if (!sp->errs)
+       sp->errs = errs_new (0);
+      if (!sp->reductions)
+       sp->reductions = reductions_new (0);
+
+      states[sp->number] = sp;

     }
 }
 
     }
 }
 

-\f

 /*-------------------------------------------------------------------.
 | Compute the nondeterministic finite state machine (see state.h for |
 | details) from the grammar.                                         |
 /*-------------------------------------------------------------------.
 | Compute the nondeterministic finite state machine (see state.h for |
 | details) from the grammar.                                         |


@@ -638,11 +399,15 @@ void
 generate_states (void)
 {
   allocate_storage ();
 generate_states (void)
 {
   allocate_storage ();

-  new_closure (nitems);
+  new_closure (nritems);

   new_states ();
 
   while (this_state)
     {
   new_states ();
 
   while (this_state)
     {

+      if (trace_flag)
+       fprintf (stderr, "Processing state %d (reached by %s)\n",
+                this_state->number,
+                symbols[this_state->accessing_symbol]->tag);

       /* 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
       /* 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


@@ -657,8 +422,7 @@ generate_states (void)
 
       /* create the shifts structures for the shifts to those states,
          now that the state numbers transitioning to are known */
 
       /* create the shifts structures for the shifts to those states,
          now that the state numbers transitioning to are known */

-      if (nshifts > 0)
-       save_shifts ();
+      save_shifts ();

 
       /* states are queued when they are created; process them all */
       this_state = this_state->next;
 
       /* states are queued when they are created; process them all */
       this_state = this_state->next;


@@ -668,6 +432,6 @@ generate_states (void)
   free_closure ();
   free_storage ();
 
   free_closure ();
   free_storage ();
 

-  /* set up initial and final states as parser wants them */
-  augment_automaton ();
+  /* Set up STATES. */
+  set_states ();

 }
 }