introduce original-states

* spot/twaalgos/degen.cc, spot/twaalgos/degen.hh,
spot/twaalgos/mask.hh: Store original states in "original-states"
properties.
* spot/twaalgos/dot.cc: Add support for option 'd'.
* bin/common_aoutput.cc: Document it.
* doc/org/concepts.org, NEWS: Document "original-states".
* tests/core/readsave.test: Add some tests.

NEWS

@@ -20,6 +20,23 @@ New in spot 2.3.3.dev (not yet released)
 
   - spot::dtwa_complement now simply returns the result of dualize()
 
+  - There is a new named property for automata called
+    "original-states" that can be used to record the origin of a state
+    when an automaton is transformed.  It is currently defined by the
+    degeneralization algorithms, and by transform_accessible() and
+    algorithms based on it (like remove_ap::strip(),
+    decompose_strength(), decompose_scc()).  This is realy meant as an
+    aid for writing algorithms that need this mapping, but it can also
+    be used to debug these algorithms: the "original-states"
+    information is displayed by the dot printer when the 'd' option is
+    passed.  For instance in
+
+      % ltl2tgba 'GF(a <-> Fb)' --dot=s
+      % ltl2tgba 'GF(a <-> Fb)' | autfilt -B --dot=ds
+
+    the second command outputs an automaton with states that show
+    references to the first one.
+
   Bugs fixed:
 
   - the transformation to state-based acceptance (spot::sbacc()) was

bin/common_aoutput.cc

@@ -92,17 +92,22 @@ static const argp_option options[] =
       OPTION_ARG_OPTIONAL,
       "GraphViz's format.  Add letters for "
       "(1) force numbered states, "
-      "(a) acceptance display, (b) acceptance sets as bullets, "
+      "(a) display acceptance, "
+      "(b) acceptance sets as bullets, "
       "(B) bullets except for Büchi/co-Büchi automata, "
       "(c) force circular nodes, "
       "(C) color nodes with COLOR, "
+      "(d) show origins when known, "
       "(e) force elliptic nodes, "
-      "(f(FONT)) use FONT, (h) horizontal layout, "
+      "(f(FONT)) use FONT, "
+      "(h) horizontal layout, "
       "(k) use state labels when possible, "
-      "(n) with name, (N) without name, "
+      "(n) with name, "
+      "(N) without name, "
       "(o) ordered transitions, "
       "(r) rainbow colors for acceptance sets, "
-      "(R) color acceptance sets by Inf/Fin, (s) with SCCs, "
+      "(R) color acceptance sets by Inf/Fin, "
+      "(s) with SCCs, "
       "(t) force transition-based acceptance, "
       "(v) vertical layout, "
       "(y) split universal edges by color, "

doc/org/concepts.org

@@ -1118,6 +1118,7 @@ Here is a list of named properties currently used inside Spot:
 |---------------------+--------------------------------+---------------------------------------------------------------------------------------------------------------------------------|
 | ~automaton-name~    | ~std::string~                  | name for the automaton, for instance to display in the HOA format                                                               |
 | ~product-states~    | ~const spot::product_states~   | vector of pairs of states giving the left and right operands of each state in a product automaton                               |
+| ~original-states~   | ~std::vector<unsigned>~        | original state number before transformation (used by some algorithms like =degeneralize()=)                                     |
 | ~state-names~       | ~std::vector<std::string>~     | vector naming each state of the automaton, for display purpose                                                                  |
 | ~highlight-edges~   | ~std::map<unsigned, unsigned>~ | map of (edge number, color number) for highlighting the output                                                                  |
 | ~highlight-states~  | ~std::map<unsigned, unsigned>~ | map of (state number, color number) for highlighting the output                                                                 |

spot/twaalgos/degen.cc

@@ -214,6 +214,10 @@ namespace spot
       // Preserve determinism, weakness, and stutter-invariance
       res->prop_copy(a, { false, true, true, true, true, true });
 
+      auto orig_states = new std::vector<unsigned>();
+      orig_states->reserve(a->num_states()); // likely more are needed.
+      res->set_named_prop("original-states", orig_states);
+
       // Create an order of acceptance conditions.  Each entry in this
       // vector correspond to an acceptance set.  Each index can
       // be used as a level in degen_state to indicate the next expected
@@ -290,16 +294,37 @@ namespace spot
             s.second = 0;
         }
 
-      ds2num[s] = res->new_state();
+      auto new_state = [&](degen_state& ds)
-      todo.emplace_back(s);
+        {
+          unsigned ns = res->new_state();
+          ds2num[ds] = ns;
+          todo.emplace_back(ds);
 
-      // If use_lvl_cache is on insert initial state to level cache
+          assert(ns == orig_states->size());
-      // Level cache stores first encountered level for each state.
+          orig_states->emplace_back(ds.first);
-      // When entering an SCC first the lvl_cache is checked.
+
-      // If such state exists level from chache is used.
+          // Level cache stores one encountered level for each state
-      // If not, a new level (starting with 0) is computed.
+          // (the value of use_lvl_cache determinates which level
-      if (use_lvl_cache)
+          // should be remembered).
-        lvl_cache[s.first] = std::make_pair(s.second, true);
+          // When entering an SCC first the lvl_cache is checked.
+          // If such state exists level from chache is used.
+          if (use_lvl_cache)
+            {
+              unsigned lvl = ds.second;
+              if (lvl_cache[ds.first].second)
+                {
+                  if (use_lvl_cache == 3)
+                    lvl = std::max(lvl_cache[ds.first].first, lvl);
+                  else if (use_lvl_cache == 2)
+                    lvl = std::min(lvl_cache[ds.first].first, lvl);
+                  else
+                    lvl = lvl_cache[ds.first].first; // Do not change
+                }
+              lvl_cache[ds.first] = std::make_pair(lvl, true);
+            }
+          return ns;
+        };
+      new_state(s);
 
       while (!todo.empty())
         {
@@ -502,31 +527,9 @@ namespace spot
               int dest;
               ds2num_map::const_iterator di = ds2num.find(d);
               if (di != ds2num.end())
-                {
+                dest = di->second;
-                  dest = di->second;
-                }
               else
-                {
+                dest = new_state(d);
-                  dest = res->new_state();
-                  ds2num[d] = dest;
-                  todo.emplace_back(d);
-                  // Insert new state to cache
-
-                  if (use_lvl_cache)
-                    {
-                      auto lvl = d.second;
-                      if (lvl_cache[d.first].second)
-                        {
-                          if (use_lvl_cache == 3)
-                            lvl = std::max(lvl_cache[d.first].first, lvl);
-                          else if (use_lvl_cache == 2)
-                            lvl = std::min(lvl_cache[d.first].first, lvl);
-                          else
-                            lvl = lvl_cache[d.first].first; // Do not change
-                        }
-                      lvl_cache[d.first] = std::make_pair(lvl, true);
-                    }
-                }
 
               unsigned& t = tr_cache[dest * 2 + is_acc];
 

spot/twaalgos/degen.hh

@@ -1,5 +1,5 @@
 // -*- coding: utf-8 -*-
-// Copyright (C) 2012, 2013, 2014 2015, Laboratoire de Recherche et
+// Copyright (C) 2012, 2013, 2014 2015, 2017, Laboratoire de Recherche et
 // Développement de l'Epita.
 //
 // This file is part of Spot, a model checking library.
@@ -48,6 +48,14 @@ namespace spot
   ///
   /// The degeneralize_tba() variant produce a degeneralized automaton
   /// with transition-based acceptance.
+  ///
+  /// The mapping between each state of the resulting automaton
+  /// and the original state of the input automaton is stored in the
+  /// "original-states" named property of the produced automaton.  Call
+  /// `aut->get_named_prop<std::vector<unsigned>>("original-states")`
+  /// to retrieve it.  Note that these functions may return the original
+  /// automaton as-is if it is already degeneralized; in this case
+  /// the "original-states" property is not defined.
   /// \@{
   SPOT_API twa_graph_ptr
   degeneralize(const const_twa_graph_ptr& a, bool use_z_lvl = true,

spot/twaalgos/dot.cc

@@ -67,6 +67,7 @@ namespace spot
       std::map<unsigned, unsigned>* highlight_edges_ = nullptr;
       std::map<unsigned, unsigned>* highlight_states_ = nullptr;
       std::vector<std::pair<unsigned, unsigned>>* sprod_ = nullptr;
+      std::vector<unsigned>* orig_ = nullptr;
       std::set<unsigned>* incomplete_ = nullptr;
       std::string* name_ = nullptr;
       acc_cond::mark_t inf_sets_ = 0U;
@@ -87,6 +88,7 @@ namespace spot
       bool opt_all_bullets = false;
       bool opt_ordered_edges_ = false;
       bool opt_numbered_edges_ = false;
+      bool opt_orig_show_ = false;
       bool max_states_given_ = false; // related to max_states_
 
       const_twa_graph_ptr aut_;
@@ -199,6 +201,9 @@ namespace spot
                 options = end + 1;
               }
               break;
+            case 'd':
+              opt_orig_show_ = true;
+              break;
             case 'e':
               opt_shape_ = ShapeEllipse;
               break;
@@ -520,6 +525,8 @@ namespace spot
                   os_ << (*sprod_)[s].first << ',' << (*sprod_)[s].second;
                 else
                   os_ << s;
+                if (orig_ && s < orig_->size())
+                  os_ << " (" << (*orig_)[s] << ')';
                 if (acc)
                   {
                     os_ << "\\n";
@@ -538,6 +545,8 @@ namespace spot
                   os_ << (*sprod_)[s].first << ',' << (*sprod_)[s].second;
                 else
                   os_ << s;
+                if (orig_ && s < orig_->size())
+                  os_ << " (" << (*orig_)[s] << ')';
                 if (acc)
                   {
                     os_ << "<br/>";
@@ -557,6 +566,8 @@ namespace spot
               os_ << (*sprod_)[s].first << ',' << (*sprod_)[s].second;
             else
               os_ << s;
+            if (orig_ && s < orig_->size())
+              os_ << " (" << (*orig_)[s] << ')';
             if (opt_state_labels_)
               escape_str(os_ << "\\n", state_label(s));
             os_ << '"';
@@ -687,6 +698,8 @@ namespace spot
                   sprod_ = nullptr;
               }
           }
+        if (opt_orig_show_)
+          orig_ = aut->get_named_prop<std::vector<unsigned>>("original-states");
         if (opt_state_labels_)
           {
             // Verify that we can use state labels for this automaton.
@@ -720,11 +733,12 @@ namespace spot
                         && aut_->prop_state_acc().is_true());
         if (opt_shape_ == ShapeAuto)
           {
-            if (sn_ || sprod_ || aut->num_states() > 100 || opt_state_labels_)
+            if (sn_ || sprod_ || aut->num_states() > 100
+                || opt_state_labels_ || orig_)
               {
                 opt_shape_ = ShapeEllipse;
                 // If all state names are short, prefer circles.
-                if (!opt_state_labels_ &&
+                if (!opt_state_labels_ && !orig_ &&
                     sn_ && std::all_of(sn_->begin(), sn_->end(),
                                        [](const std::string& s)
                                        { return s.size() <= 2; }))

spot/twaalgos/mask.hh

@@ -25,19 +25,26 @@ namespace spot
 {
   /// \brief Clone and mask an automaton.
   ///
-  /// Copy the edges of automaton \a old, into automaton
+  /// Copy the edges of automaton \a old into the empty automaton \a
-  /// \a cpy, creating new states at the same time.  The argument \a
+  /// cpy, creating new states as needed.  The argument \a trans
-  /// trans should behave as a function with the following prototype:
+  /// should behave as a function with the following prototype:
   /// <code>
   ///   void (*trans) (unsigned src, bdd& cond, acc_cond::mark_t& acc,
   ///   unsigned dst)
   /// </code>
-  /// It can modify either the condition or the acceptance sets of
+  ///
-  /// the edges.  Set the condition to bddfalse to remove the edge
+  /// The \a trans function may modify either the condition or the
-  /// (this will also remove the destination state and its descendants
+  /// acceptance sets of the edges.  Set the condition to bddfalse to
-  /// if they are not reachable by another edge).
+  /// remove the edge (this will also remove the destination state and
+  /// its descendants if they are not reachable by another edge).
+  ///
+  /// The mapping between each state of the resulting automaton
+  /// and the original state of the input automaton is stored in the
+  /// "original-states" named property of the produced automaton.  Call
+  /// `aut->get_named_prop<std::vector<unsigned>>("original-states")`
+  /// to retrieve it.
+  ///
   /// \param init The optional new initial state.
-
   template<typename Trans>
   void transform_accessible(const const_twa_graph_ptr& old,
                             twa_graph_ptr& cpy,
@@ -50,6 +57,10 @@ namespace spot
     std::vector<unsigned> todo;
     std::vector<unsigned> seen(old->num_states(), -1U);
 
+    auto orig_states = new std::vector<unsigned>();
+    orig_states->reserve(old->num_states()); // maybe less are needed.
+    cpy->set_named_prop("original-states", orig_states);
+
     auto new_state =
       [&](unsigned old_state) -> unsigned
       {
@@ -58,12 +69,17 @@ namespace spot
           {
             tmp = cpy->new_state();
             seen[old_state] = tmp;
+            orig_states->emplace_back(old_state);
             todo.emplace_back(old_state);
           }
         return tmp;
       };
 
     cpy->set_init_state(new_state(init));
+    if (seen[init] != 0)
+      throw std::runtime_error
+        ("the destination automaton of transform_accessible() should be empty");
+
     while (!todo.empty())
       {
         unsigned old_src = todo.back();
@@ -79,11 +95,12 @@ namespace spot
             trans(t.src, cond, acc, t.dst);
 
             if (cond != bddfalse)
-              cpy->new_edge(new_src,
+              cpy->new_edge(new_src, new_state(t.dst),
-                                  new_state(t.dst),
+                            cond, acc);
-                                  cond, acc);
           }
       }
+
+    orig_states->shrink_to_fit();
   }
 
   /// \brief Copy an automaton and update each edge.
@@ -133,6 +150,7 @@ namespace spot
   {
     transform_accessible(old, cpy, trans, old->get_init_state_number());
   }
+
   template<typename Trans>
   void transform_copy(const const_twa_graph_ptr& old,
                       twa_graph_ptr& cpy,

tests/core/readsave.test

@@ -1,6 +1,6 @@
 #!/bin/sh
 # -*- coding: utf-8 -*-
-# Copyright (C) 2009, 2010, 2012, 2014, 2015, 2016 Laboratoire de
+# Copyright (C) 2009, 2010, 2012, 2014, 2015, 2016, 2017 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
@@ -1041,3 +1041,26 @@ test 2 = `ltl2tgba 'GFa' 'a U b' 'a U b U c'| autfilt --ap=2..3 --count`
 test 2 = `genltl --dac=1..3 | ltl2tgba --stats='%e,"%h",%s' |
           dstar2tgba -F-/2 --stats='%<,%>,"%h"' |
           autfilt --states=2..3 -F-/3 --stats='%<,"%h"' | wc -l`
+
+# --dot=d
+ltl2tgba 'GF(a <-> Fb)' | autfilt -B --dot=d | grep ' (' >out
+cat >expected <<EOF
+  0 [label="0 (0)", peripheries=2]
+  1 [label="1 (0)"]
+  2 [label="2 (1)"]
+  3 [label="3 (2)", peripheries=2]
+  4 [label="4 (2)"]
+EOF
+diff out expected
+# --dot=d should also not use circles
+ltl2tgba 'a U b' | autfilt --remove-ap=b=0 --dot=d >out
+cat >expected <<EOF
+digraph G {
+  rankdir=LR
+  I [label="", style=invis, width=0]
+  I -> 0
+  0 [label="0 (1)"]
+  0 -> 0 [label="a"]
+}
+EOF
+diff out expected