safra: implement powerset construction

* spot/twaalgos/Makefile.am: Update it.
* src/twaalgos/safra.cc, src/twaalgos/safra.hh: New.

src/twaalgos/safra.hh

@@ -0,0 +1,80 @@
+// -*- coding: utf-8 -*-
+// Copyright (C) 2015 Laboratoire de Recherche et Développement
+// de l'Epita.
+//
+// This file is part of Spot, a model checking library.
+//
+// Spot 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.
+//
+// Spot 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/>.
+
+#pragma once
+
+#include <set>
+
+#include "misc/bddlt.hh"
+#include "twa/twagraph.hh"
+
+namespace spot
+{
+  class safra_state
+  {
+    class node
+    {
+    public:
+      using brace_t = size_t;
+
+      bool operator==(const node& other) const;
+      bool operator<(const node& other) const;
+      void disable_construction() { in_construction_ = false; }
+      node(unsigned id)
+        : id_(id), in_construction_(true) {}
+      node(unsigned id, brace_t b_id, bool in_construction = true)
+        : id_(id), braces_(1, b_id), in_construction_(in_construction) {}
+      node(unsigned id, std::vector<brace_t> b, bool in_construction = true)
+        : id_(id), braces_(b), in_construction_(in_construction) {}
+      // The name used to identify a state
+      unsigned id_;
+      // The list of braces the state is nested in.
+      std::vector<brace_t> braces_;
+      // Hack to have two comparision functions during construction and after
+      // construction
+      // During construction only the nodes id matterns as the braces are under
+      // construction. After construction (id, braces) is what distinguishes a
+      // node.
+      bool in_construction_;
+    };
+
+  public:
+    typedef std::vector<std::pair<safra_state, bdd>> succs_t;
+    bool operator<(const safra_state& other) const;
+    safra_state(unsigned state_number, bool init_state = false);
+    // Given a certain transition_label, compute all the successors of that
+    // label, and return that new node.
+    succs_t compute_succs(const const_twa_graph_ptr& aut) const;
+    // Used when creating the list of successors
+    void update_succ(const node& src, unsigned dst, const acc_cond::mark_t);
+    void finalize_construction();
+    // A list of nodes similar to the ones of a
+    // safra tree.  These are constructed in the same way as the powerset
+    // algorithm.
+    std::set<node> nodes_;
+    // A counter that indicates the nomber of states within a brace.
+    // This enables us to compute the red value
+    std::vector<size_t> nb_braces_;
+    // A bitfield to know if a brace can emit green.
+    std::vector<bool> is_green_;
+  };
+
+  SPOT_API twa_graph_ptr
+  tgba_determinisation(const const_twa_graph_ptr& aut);
+}