* src/lex.c, src/lex.h (xgetc): No longer static.

[bison.git] / src / LR0.c

diff --git a/src/LR0.c b/src/LR0.c
index ff5fdb614123433ca3ccae7a386304b3fac067cd..5e8caef046bd4bf12751459bd53534b7d4c95a7c 100644 (file)
--- a/src/LR0.c
+++ b/src/LR0.c
@@ -30,18 +30,15 @@
 #include "complain.h"
 #include "closure.h"
 #include "LR0.h"
 #include "complain.h"
 #include "closure.h"
 #include "LR0.h"

+#include "lalr.h"

 #include "reduce.h"
 
 int nstates;
 int final_state;
 #include "reduce.h"
 
 int nstates;
 int final_state;

-state_t *first_state = NULL;
-shifts *first_shift = NULL;
-reductions *first_reduction = NULL;
+static state_t *first_state = NULL;

 
 static state_t *this_state = NULL;
 static state_t *last_state = NULL;
 
 static state_t *this_state = NULL;
 static state_t *last_state = NULL;

-static shifts *last_shift = NULL;
-static reductions *last_reduction = NULL;

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


@@ -319,32 +316,34 @@ static void
 save_shifts (void)
 {
   shifts *p = shifts_new (nshifts);
 save_shifts (void)
 {
   shifts *p = shifts_new (nshifts);

-
-  p->number = this_state->number;
-

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

-
-  if (last_shift)
-    last_shift->next = p;
-  else
-    first_shift = p;
-  last_shift = p;
+  this_state->shifts = p;

 }
 
 
 /*------------------------------------------------------------------.
 | Subroutine of augment_automaton.  Create the next-to-final state, |
 | to which a shift has already been made in the initial state.      |
 }
 
 
 /*------------------------------------------------------------------.
 | 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.                                          |

 `------------------------------------------------------------------*/
 
 static void
 `------------------------------------------------------------------*/
 
 static void

-insert_start_shift (void)
+insert_start_shifting_state (void)

 {
   state_t *statep;
   shifts *sp;
 
   statep = STATE_ALLOC (0);
 {
   state_t *statep;
   shifts *sp;
 
   statep = STATE_ALLOC (0);

-  statep->number = nstates;
+  statep->number = nstates++;
+
+  /* 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;
   statep->accessing_symbol = start_symbol;
 
   last_state->next = statep;


@@ -352,14 +351,63 @@ insert_start_shift (void)
 
   /* Make a shift from this state to (what will be) the final state.  */
   sp = shifts_new (1);
 
   /* Make a shift from this state to (what will be) the final state.  */
   sp = shifts_new (1);

-  sp->number = nstates++;
+  statep->shifts = sp;

   sp->shifts[0] = nstates;
   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.                                        |
+`-----------------------------------------------------------------*/
+
+static void
+insert_eof_shifting_state (void)
+{
+  state_t *statep;
+  shifts *sp;
+
+  /* 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++;
+
+  last_state->next = statep;
+  last_state = statep;

 
 

-  last_shift->next = sp;
-  last_shift = sp;
+  /* Make the shift from the final state to the termination state.  */
+  sp = shifts_new (1);
+  statep->shifts = sp;
+  sp->shifts[0] = nstates;

 }
 
 
 }
 
 

+/*---------------------------------------------------------------.
+| Subroutine of augment_automaton.  Create the accepting state.  |
+`---------------------------------------------------------------*/
+
+static void
+insert_accepting_state (void)
+{
+  state_t *statep;
+
+   /* Note that the variable `final_state' refers to what we sometimes
+      call the termination state.  */
+  final_state = nstates;
+
+  /* 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 |
 /*------------------------------------------------------------------.
 | 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 |


@@ -371,156 +419,83 @@ insert_start_shift (void)
 static void
 augment_automaton (void)
 {
 static void
 augment_automaton (void)
 {

-  state_t *statep;
-  shifts *sp;
-  shifts *sp1 = NULL;
-
-  sp = first_shift;
-
-  if (!sp->nshifts)
+  if (!first_state->shifts->nshifts)

     {
     {

-      /* There are no shifts for any state.  Make one shift, from the
+      /* The first state has no shifts.  Make one shift, from the

         initial state to the next-to-final state.  */
 
         initial state to the next-to-final state.  */
 

-      sp = shifts_new (1);
+      shifts *sp = shifts_new (1);
+      first_state->shifts = sp;

       sp->shifts[0] = nstates;
 
       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.  */
       /* Create the next-to-final state, with shift to
          what will be the final state.  */

-      insert_start_shift ();
+      insert_start_shifting_state ();

     }
     }

-  else if (sp->number == 0)
+  else

     {
     {

-      statep = first_state->next;
-
+      state_t *statep = first_state->next;

       /* The states reached by shifts from FIRST_STATE are numbered
       /* The states reached by shifts from FIRST_STATE are numbered

-        1..(SP->NSHIFTS).  Look for one reached by START_SYMBOL.  */
-      while (statep->accessing_symbol < start_symbol
-            && statep->number < sp->nshifts)
+        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)
        {
        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.  */
-         while (sp && sp->number < statep->number)
-           {
-             sp1 = sp;
-             sp = sp->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;

 
 

-         if (sp && sp->number == statep->number)
-           {
-             int i;
-             shifts *sp2 = shifts_new (sp->nshifts + 1);
-             sp2->number = statep->number;
-             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
-           {
-             shifts *sp2 = shifts_new (1);
-             sp2->number = statep->number;
-             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;
-           }
+         /* Find the shift of the inital state that leads to STATEP.  */
+         shifts *sp = statep->shifts;
+
+         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];
+
+         XFREE (sp);
+
+         insert_eof_shifting_state ();

        }
       else
        {
        }
       else
        {

+         /* There is no state for `start: start . ...'. */

          int i, k;
          int i, k;

-         shifts *sp2;
-
-         /* 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_new (sp->nshifts + 1);
+         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)
          /* 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];
+               sp1->shifts[k++] = nstates;
+             sp1->shifts[k] = sp->shifts[i];

              statep = statep->next;
            }
          if (i == k)
              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;
+           sp1->shifts[k++] = nstates;

 
          XFREE (sp);
 
 
          XFREE (sp);
 

-         /* Create the next-to-final state, with shift to
-            what will be the final state.  */
-         insert_start_shift ();
+         /* Create the next-to-final state, with shift to what will
+            be the final state.  Corresponds to `start: start . ...'.  */
+         insert_start_shifting_state ();

        }
     }
        }
     }

-  else
-    {
-      /* The initial state didn't even have any shifts.
-        Give it one shift, to the next-to-final state.  */
-      sp = shifts_new (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 ();
-    }
-
-  /* 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;
-  last_state->next = statep;
-  last_state = statep;

 
 

-  /* Make the shift from the final state to the termination state.  */
-  sp = shifts_new (1);
-  sp->number = nstates++;
-  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 = STATE_ALLOC (0);
-  statep->number = nstates++;
-  last_state->next = statep;
-  last_state = statep;
+  insert_accepting_state ();

 }
 
 
 }
 
 


@@ -551,21 +526,42 @@ save_reductions (void)
   if (count)
     {
       reductions *p = REDUCTIONS_ALLOC (count);
   if (count)
     {
       reductions *p = REDUCTIONS_ALLOC (count);

-
-      p->number = this_state->number;

       p->nreds = count;
       p->nreds = count;

-

       shortcpy (p->rules, redset, count);
 
       shortcpy (p->rules, redset, count);
 

-      if (last_reduction)
-       last_reduction->next = p;
-      else
-       first_reduction = p;
-      last_reduction = p;
+      this_state->reductions = p;

     }
 }
 
 \f
     }
 }
 
 \f

+/*--------------------.
+| Build STATE_TABLE.  |
+`--------------------*/
+
+static void
+set_state_table (void)
+{
+  /* 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);
+  }
+}
+

 /*-------------------------------------------------------------------.
 | 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.                                         |


@@ -609,4 +605,7 @@ generate_states (void)
 
   /* set up initial and final states as parser wants them */
   augment_automaton ();
 
   /* set up initial and final states as parser wants them */
   augment_automaton ();

+
+  /* Set up STATE_TABLE. */
+  set_state_table ();

 }
 }