Move the free_list management into a separate class for reuse.

* src/misc/freelist.hh, src/misc/freelist.cc: New files.
* src/misc/Makefile.am (misc_HEADERS, libmisc_la_SOURCES): Add them.
* src/misc/bddalloc.hh (bdd_allocator): Inherit from free_list and
make dump_free_list visible.
* src/misc/bddalloc.cc (bdd_allocator::allocate_variables): Move
all the code into free_list::register_n() and
bdd_allocator::extend(), and call the former.
(bdd_allocator::release_variables): Move all the code into
free_list::release_n() and call it.
(bdd_allocator::extend): New method.
* src/tgba/bdddict.cc (bdd_dict::dump): Call dump_free_list;

src/misc/freelist.hh

@@ -0,0 +1,69 @@
+// Copyright (C) 2004  Laboratoire d'Informatique de Paris 6 (LIP6),
+// département Systèmes Répartis Coopératifs (SRC), Université Pierre
+// et Marie Curie.
+//
+// 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 2 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 Spot; see the file COPYING.  If not, write to the Free
+// Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+// 02111-1307, USA.
+
+
+#ifndef SPOT_MISC_FREELIST_HH
+# define SPOT_MISC_FREELIST_HH
+
+#include <list>
+#include <utility>
+
+namespace spot
+{
+
+  /// Manage list of free integers.
+  class free_list
+  {
+  public:
+    virtual ~free_list();
+
+    /// \brief Find \a n consecutive integers.
+    ///
+    /// Browse the list of free integers until \a n consecutive
+    /// integers are found.  Extend the list (using extend()) otherwise.
+    /// \return the first integer of the range
+    int register_n(int n);
+
+    /// Release \a n consecutive integers starting at \a base.
+    void release_n(int base, int n);
+
+    /// Dump the list to \a os for debugging.
+    std::ostream& dump_free_list(std::ostream& os) const;
+  protected:
+
+    /// Allocate \a n integer.
+    ///
+    /// This function is called by register_n() when the free list is
+    /// empty or if \a n consecutive integers could not be found.  It
+    /// should allocate more integers, possibly changing the list, and
+    /// return the first integer on a range of n consecutive integer
+    /// requested by the user.
+    virtual int extend(int n) = 0;
+
+    /// Such pairs describe \c second free integer starting at \first.
+    typedef std::pair<int, int> pos_lenght_pair;
+    typedef std::list<pos_lenght_pair> free_list_type;
+    free_list_type fl; ///< Tracks unused BDD variables.
+  };
+
+}
+
+#endif // SPOT_MISC_FREELIST_HH