Add a cleanup_acceptance() algorithm

* src/tgbaalgos/cleanacc.cc, src/tgbaalgos/cleanacc.hh: New file.
* src/tgbaalgos/Makefile.am: Add them.
* src/tgba/acc.hh, src/tgba/tgba.hh (get_acceptance): Return a
reference.
* src/bin/autfilt.cc: Add a --cleanup-acceptance option.
* src/tgbatest/hoaparse.test: Test it.

src/tgbaalgos/cleanacc.cc

@@ -0,0 +1,135 @@
+// -*- 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/>.
+
+#include "tgbaalgos/cleanacc.hh"
+
+namespace spot
+{
+  namespace
+  {
+    acc_cond::acc_code strip(const acc_cond& acc,
+			     const acc_cond::acc_word* pos,
+			     acc_cond::mark_t useless)
+    {
+      auto start = pos - pos->size;
+      switch (pos->op)
+	{
+	case acc_cond::acc_op::And:
+	  {
+	    --pos;
+	    acc_cond::acc_code res;
+	    do
+	      {
+		auto tmp = strip(acc, pos, useless);
+		tmp.append_and(std::move(res));
+		std::swap(tmp, res);
+		pos -= pos->size + 1;
+	      }
+	    while (pos > start);
+	    return res;
+	  }
+	case acc_cond::acc_op::Or:
+	  {
+	    --pos;
+	    acc_cond::acc_code res = acc.fin(0); // f
+	    do
+	      {
+		auto tmp = strip(acc, pos, useless);
+		tmp.append_or(std::move(res));
+		std::swap(tmp, res);
+		pos -= pos->size + 1;
+	      }
+	    while (pos > start);
+	    return res;
+	  }
+	case acc_cond::acc_op::Fin:
+	  if (pos[-1].mark & useless)
+	    return acc.inf(0U);	// t
+	  return acc.fin(acc.strip(pos[-1].mark, useless));
+	case acc_cond::acc_op::Inf:
+	  if (pos[-1].mark & useless)
+	    return acc.fin(0U);	// f
+	  return acc.inf(acc.strip(pos[-1].mark, useless));
+	case acc_cond::acc_op::FinNeg:
+	case acc_cond::acc_op::InfNeg:
+	  SPOT_UNREACHABLE();
+	  return acc_cond::acc_code{};
+	}
+      SPOT_UNREACHABLE();
+      return acc_cond::acc_code{};
+    }
+  }
+
+  void cleanup_acceptance(tgba_digraph_ptr& aut)
+  {
+    auto& acc = aut->acc();
+    if (acc.num_sets() == 0)
+      return;
+
+    auto& c = aut->get_acceptance();
+    acc_cond::mark_t used_in_cond = 0U;
+    if (!c.is_true())
+      {
+	auto pos = &c.back();
+	auto end = &c.front();
+	while (pos > end)
+	  {
+	    switch (pos->op)
+	      {
+	      case acc_cond::acc_op::And:
+	      case acc_cond::acc_op::Or:
+		--pos;
+		break;
+	      case acc_cond::acc_op::Fin:
+	      case acc_cond::acc_op::Inf:
+	      case acc_cond::acc_op::FinNeg:
+	      case acc_cond::acc_op::InfNeg:
+		used_in_cond |= pos[-1].mark;
+		pos -= 2;
+		break;
+	      }
+	  }
+      }
+
+    acc_cond::mark_t used_in_aut = 0U;
+    for (auto& t: aut->transitions())
+      used_in_aut |= t.acc;
+
+    auto useful = used_in_aut & used_in_cond;
+
+    auto useless = acc.comp(useful);
+
+    if (!useless)
+      return;
+
+    // Remove useless marks from the automaton
+    for (auto& t: aut->transitions())
+      t.acc = acc.strip(t.acc, useless);
+
+    // Remove useless marks from the acceptance condition
+    acc_cond::acc_code newc;
+    if (c.is_true() || c.is_false())
+      newc = c;
+    else
+      newc = strip(acc, &c.back(), useless);
+
+    aut->set_acceptance(useful.count(), newc);
+  }
+
+}