doc: one of the fixes for an ambiguous grammar was ambiguous too

[bison.git] / src / print_graph.c

/* Output a graph of the generated parser, for Bison.

   Copyright (C) 2001-2007, 2009-2012 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/>.  */

#include <config.h>
#include "system.h"

#include "LR0.h"
#include "closure.h"
#include "complain.h"
#include "conflicts.h"
#include "files.h"
#include "getargs.h"
#include "gram.h"
#include "graphviz.h"
#include "lalr.h"
#include "print_graph.h"
#include "reader.h"
#include "state.h"
#include "symtab.h"


/*----------------------------.
| Construct the node labels.  |
`----------------------------*/

static void
print_core (struct obstack *oout, state *s)
{
  size_t i;
  item_number *sitems = s->items;
  size_t snritems = s->nitems;

  /* Output all the items of a state, not only its kernel.  */
  if (report_flag & report_itemsets)
    {
      closure (sitems, snritems);
      sitems = itemset;
      snritems = nitemset;
    }

  obstack_printf (oout, "%d", s->number);
  for (i = 0; i < snritems; i++)
    {
      item_number *sp;
      item_number *sp1;
      rule_number r;

      sp1 = sp = ritem + sitems[i];

      while (*sp >= 0)
	sp++;

      r = item_number_as_rule_number (*sp);

      obstack_printf (oout, "\n%s -> ", rules[r].lhs->tag);

      for (sp = rules[r].rhs; sp < sp1; sp++)
	obstack_printf (oout, "%s ", symbols[*sp]->tag);

      obstack_1grow (oout, '.');

      for (/* Nothing */; *sp >= 0; ++sp)
	obstack_printf (oout, " %s", symbols[*sp]->tag);

      /* Experimental feature: display the lookahead tokens. */
      if (report_flag & report_lookahead_tokens
          && item_number_is_rule_number (*sp1))
	{
	  /* Find the reduction we are handling.  */
	  reductions *reds = s->reductions;
	  int redno = state_reduction_find (s, &rules[r]);

	  /* Print them if there are.  */
	  if (reds->lookahead_tokens && redno != -1)
	    {
	      bitset_iterator biter;
	      int k;
	      char const *sep = "";
	      obstack_sgrow (oout, "[");
	      BITSET_FOR_EACH (biter, reds->lookahead_tokens[redno], k, 0)
		{
		  obstack_printf (oout, "%s%s", sep, symbols[k]->tag);
		  sep = ", ";
		}
	      obstack_sgrow (oout, "]");
	    }
	}
    }
}


/*---------------------------------------------------------------.
| Output in graph_obstack edges specifications in incidence with |
| current node.                                                  |
`---------------------------------------------------------------*/

static void
print_actions (state const *s, FILE *fgraph)
{
  int i;

  transitions const *trans = s->transitions;

  if (!trans->num && !s->reductions)
    return;

  for (i = 0; i < trans->num; i++)
    if (!TRANSITION_IS_DISABLED (trans, i))
      {
	state *s1 = trans->states[i];
	symbol_number sym = s1->accessing_symbol;

	/* Shifts are solid, gotos are dashed, and error is dotted.  */
	char const *style =
	  (TRANSITION_IS_ERROR (trans, i) ? "dotted"
	   : TRANSITION_IS_SHIFT (trans, i) ? "solid"
	   : "dashed");

	if (TRANSITION_IS_ERROR (trans, i)
	    && strcmp (symbols[sym]->tag, "error") != 0)
	  abort ();
	output_edge (s->number, s1->number,
		     TRANSITION_IS_ERROR (trans, i) ? NULL : symbols[sym]->tag,
		     style, fgraph);
      }
}


/*-------------------------------------------------------------.
| Output in FGRAPH the current node specifications and exiting |
| edges.                                                       |
`-------------------------------------------------------------*/

static void
print_state (state *s, FILE *fgraph)
{
  struct obstack node_obstack;

  /* A node's label contains its items.  */
  obstack_init (&node_obstack);
  print_core (&node_obstack, s);
  obstack_1grow (&node_obstack, '\0');
  output_node (s->number, obstack_finish (&node_obstack), fgraph);
  obstack_free (&node_obstack, 0);

  /* Output the edges.  */
  print_actions (s, fgraph);
}
\f

void
print_graph (void)
{
  state_number i;
  FILE *fgraph = xfopen (spec_graph_file, "w");
  start_graph (fgraph);

  /* Output nodes and edges. */
  new_closure (nritems);
  for (i = 0; i < nstates; i++)
    print_state (states[i], fgraph);
  free_closure ();

  finish_graph (fgraph);
  xfclose (fgraph);
}