dot: add option 'g'

* spot/twaalgos/dot.cc: Implement support for hidding labels.
* tests/core/readsave.test: Test it.
* bin/common_aoutput.cc: Add --help text.
* NEWS: Mention it.

NEWS

@@ -35,6 +35,10 @@ New in spot 2.7.2.dev (not yet released)
     by spot::generic_emptiness_check() when processing SCCs
     recursively, and makes it easier to write similar code in Python.
 
+  - print_dot has a new option 'g', to hide edge labels.  This is
+    helpful to display automata as "graphs", e.g., when illustrating
+    algorithms that do not care about labels.
+
   Bugs fixed:
 
   - When processing CSV files with MSDOS-style \r\n line endings,

bin/common_aoutput.cc

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2012-2018 Laboratoire de Recherche et Développement
+// Copyright (C) 2012-2019 Laboratoire de Recherche et Développement
 // de l'Epita (LRDE).
 //
 // This file is part of Spot, a model checking library.
@@ -101,6 +101,7 @@ static const argp_option options[] =
       "(d) show origins when known, "
       "(e) force elliptic nodes, "
       "(f(FONT)) use FONT, "
+      "(g) hide edge labels, "
       "(h) horizontal layout, "
       "(k) use state labels when possible, "
       "(K) use transition labels (default), "

spot/twaalgos/dot.cc

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2011, 2012, 2014-2018 Laboratoire de Recherche
+// Copyright (C) 2011, 2012, 2014-2019 Laboratoire de Recherche
 // et Développement de l'Epita (LRDE).
 // Copyright (C) 2003, 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
 // département Systèmes Répartis Coopératifs (SRC), Université Pierre
@@ -108,6 +108,7 @@ namespace spot
       bool opt_orig_show_ = false;
       bool max_states_given_ = false; // related to max_states_
       bool opt_latex_ = false;
+      bool opt_showlabel_ = true;
       const char* nl_ = "\\n";
       const char* label_pre_ = "label=\"";
       char label_post_ = '"';
@@ -266,6 +267,9 @@ namespace spot
                 options = end + 1;
               }
               break;
+            case 'g':           // "graphs" are unlabeled automata
+              opt_showlabel_ = false;
+              break;
             case 'h':
               opt_vertical_ = false;
               break;
@@ -756,12 +760,12 @@ namespace spot
                   os_ << '.' << iter->second % palette_mod;
               }
             os_ << " [" << label_pre_;
-            if (!opt_state_labels_)
+            if (!opt_state_labels_ && opt_showlabel_)
               format_label(os_, t.cond);
             if (!mark_states_)
               if (auto a = t.acc)
                 {
-                  if (!opt_state_labels_)
+                  if (!opt_state_labels_ && opt_showlabel_)
                     os_ << nl_;
                   output_mark(a);
                 }

tests/core/readsave.test

@@ -1,6 +1,6 @@
 #!/bin/sh
 # -*- coding: utf-8 -*-
-# Copyright (C) 2009, 2010, 2012, 2014-2018 Laboratoire de
+# Copyright (C) 2009, 2010, 2012, 2014-2019 Laboratoire de
 # Recherche et Développement de l'Epita (LRDE).
 # Copyright (C) 2003, 2004 Laboratoire d'Informatique de Paris 6 (LIP6),
 # département Systèmes Répartis Coopératifs (SRC), Université Pierre
@@ -390,6 +390,25 @@ digraph "G(Fa & Fb)" {
 EOF
 diff output expected
 
+ltl2tgba -dbang 'GFa & GFb' >output
+cat output
+cat >expected <<EOF
+digraph "G(Fa & Fb)" {
+  rankdir=LR
+  label="G(Fa & Fb)\nInf(⓿)&Inf(❶)\n[gen. Büchi 2]"
+  labelloc="t"
+  node [shape="circle"]
+  I [label="", style=invis, width=0]
+  I -> 0
+  0 [label="0"]
+  0 -> 0 [label=""]
+  0 -> 0 [label="❶"]
+  0 -> 0 [label="⓿"]
+  0 -> 0 [label="⓿❶"]
+}
+EOF
+diff output expected
+
 
 SPOT_DOTDEFAULT=bra ltl2tgba --dot='Ae.f(Lato)' 'GFa & GFb' >output
 cat output