src/print-graph.c

   1 /* Output a graph of the generated parser, for Bison.
   2
   3    Copyright (C) 2001-2007, 2009-2015, 2018-2021 Free Software
   4    Foundation, Inc.
   5
   6    This file is part of Bison, the GNU Compiler Compiler.
   7
   8    This program is free software: you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation, either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  20
  21 #include <config.h>
  22 #include "print-graph.h"
  23
  24 #include "system.h"
  25
  26 #include "closure.h"
  27 #include "complain.h"
  28 #include "conflicts.h"
  29 #include "files.h"
  30 #include "getargs.h"
  31 #include "gram.h"
  32 #include "graphviz.h"
  33 #include "lalr.h"
  34 #include "lr0.h"
  35 #include "reader.h"
  36 #include "state.h"
  37 #include "symtab.h"
  38
  39
  40 /*----------------------------.
  41 | Construct the node labels.  |
  42 `----------------------------*/
  43
  44 /* Print the lhs of a rule in such a manner that there is no vertical
  45    repetition, like in *.output files. */
  46
  47 static void
  48 print_core (struct obstack *oout, state *s)
  49 {
  50   item_index const *sitems = s->items;
  51   sym_content *previous_lhs = NULL;
  52   size_t snritems = s->nitems;
  53
  54   /* Output all the items of a state, not just its kernel.  */
  55   if (report_flag & report_itemsets)
  56     {
  57       closure (sitems, snritems);
  58       sitems = itemset;
  59       snritems = nitemset;
  60     }
  61
  62   obstack_printf (oout, _("State %d"), s->number);
  63   obstack_sgrow (oout, "\\n\\l");
  64   for (size_t i = 0; i < snritems; ++i)
  65     {
  66       item_number const *sp1 = ritem + sitems[i];
  67       rule const *r = item_rule (sp1);
  68
  69       obstack_printf (oout, "%3d ", r->number);
  70       if (previous_lhs && UNIQSTR_EQ (previous_lhs->symbol->tag,
  71                                       r->lhs->symbol->tag))
  72         obstack_printf (oout, "%*s| ",
  73                         (int) strlen (previous_lhs->symbol->tag), "");
  74       else
  75         {
  76           obstack_backslash (oout, r->lhs->symbol->tag);
  77           obstack_printf (oout, ": ");
  78         }
  79       previous_lhs = r->lhs;
  80
  81       for (item_number const *sp = r->rhs; sp < sp1; sp++)
  82         {
  83           obstack_backslash (oout, symbols[*sp]->tag);
  84           obstack_1grow (oout, ' ');
  85         }
  86
  87       obstack_sgrow (oout, "•");
  88
  89       if (0 <= *r->rhs)
  90         for (item_number const *sp = sp1; 0 <= *sp; ++sp)
  91           {
  92             obstack_1grow (oout, ' ');
  93             obstack_backslash (oout, symbols[*sp]->tag);
  94           }
  95       else
  96         obstack_sgrow (oout, " %empty");
  97
  98       /* Experimental feature: display the lookahead tokens. */
  99       if (report_flag & report_lookaheads
 100           && item_number_is_rule_number (*sp1))
 101         {
 102           /* Find the reduction we are handling.  */
 103           reductions *reds = s->reductions;
 104           int redno = state_reduction_find (s, r);
 105
 106           /* Print them if there are.  */
 107           if (reds->lookaheads && redno != -1)
 108             {
 109               bitset_iterator biter;
 110               int k;
 111               char const *sep = "";
 112               obstack_sgrow (oout, "  [");
 113               BITSET_FOR_EACH (biter, reds->lookaheads[redno], k, 0)
 114                 {
 115                   obstack_sgrow (oout, sep);
 116                   obstack_backslash (oout, symbols[k]->tag);
 117                   sep = ", ";
 118                 }
 119               obstack_1grow (oout, ']');
 120             }
 121         }
 122       obstack_sgrow (oout, "\\l");
 123     }
 124 }
 125
 126
 127 /*---------------------------------------------------------------.
 128 | Output in graph_obstack edges specifications in incidence with |
 129 | current node.                                                  |
 130 `---------------------------------------------------------------*/
 131
 132 static void
 133 print_actions (state const *s, FILE *fgraph)
 134 {
 135   transitions const *trans = s->transitions;
 136
 137   if (!trans->num && !s->reductions)
 138     return;
 139
 140   for (int i = 0; i < trans->num; i++)
 141     if (!TRANSITION_IS_DISABLED (trans, i))
 142       {
 143         const state *s1 = trans->states[i];
 144         const symbol_number sym = s1->accessing_symbol;
 145
 146         /* Shifts are solid, gotos are dashed, and error is dotted.  */
 147         char const *style =
 148           (TRANSITION_IS_ERROR (trans, i) ? "dotted"
 149            : TRANSITION_IS_SHIFT (trans, i) ? "solid"
 150            : "dashed");
 151
 152         if (TRANSITION_IS_ERROR (trans, i)
 153             && STRNEQ (symbols[sym]->tag, "error"))
 154           abort ();
 155         output_edge (s->number, s1->number,
 156                      TRANSITION_IS_ERROR (trans, i) ? NULL : symbols[sym]->tag,
 157                      style, fgraph);
 158       }
 159   /* Display reductions. */
 160   output_red (s, s->reductions, fgraph);
 161 }
 162
 163
 164 /*-------------------------------------------------------------.
 165 | Output in FGRAPH the current node specifications and exiting |
 166 | edges.                                                       |
 167 `-------------------------------------------------------------*/
 168
 169 static void
 170 print_state (state *s, FILE *fgraph)
 171 {
 172   struct obstack node_obstack;
 173
 174   /* A node's label contains its items.  */
 175   obstack_init (&node_obstack);
 176   print_core (&node_obstack, s);
 177   output_node (s->number, obstack_finish0 (&node_obstack), fgraph);
 178   obstack_free (&node_obstack, 0);
 179
 180   /* Output the edges.  */
 181   print_actions (s, fgraph);
 182 }
 183 \f
 184
 185 void
 186 print_graph (void)
 187 {
 188   FILE *fgraph = xfopen (spec_graph_file, "w");
 189   start_graph (fgraph);
 190
 191   /* Output nodes and edges. */
 192   for (int i = 0; i < nstates; i++)
 193     print_state (states[i], fgraph);
 194
 195   finish_graph (fgraph);
 196   xfclose (fgraph);
 197 }