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.cc

@@ -0,0 +1,118 @@
+// 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.
+
+#include "freelist.hh"
+#include <cassert>
+#include <iostream>
+
+namespace spot
+{
+
+  free_list::~free_list()
+  {
+  }
+
+  int
+  free_list::register_n(int n)
+  {
+    // Browse the free list until we find N consecutive variables.  We
+    // try not to fragment the list my allocating the variables in the
+    // smallest free range we find.
+    free_list_type::iterator best = fl.end();
+    free_list_type::iterator cur;
+    for (cur = fl.begin(); cur != fl.end(); ++cur)
+      {
+	if (cur->second < n)
+	  continue;
+	if (n == cur->second)
+	  {
+	    best = cur;
+	    break;
+	  }
+	if (best == fl.end()
+	    || cur->second < best->second)
+	  best = cur;
+      }
+
+    // We have found enough free variables.
+    if (best != fl.end())
+      {
+	int result = best->first;
+	best->second -= n;
+	assert(best->second >= 0);
+	// Erase the range if it's now empty.
+	if (best->second == 0)
+	  fl.erase(best);
+	else
+	  best->first += n;
+	return result;
+      }
+
+    // We haven't found enough adjacent free variables;
+    // ask for some more.
+    return extend(n);
+  }
+
+  void
+  free_list::release_n(int base, int n)
+  {
+    free_list_type::iterator cur;
+    int end = base + n;
+    for (cur = fl.begin(); cur != fl.end(); ++cur)
+      {
+	// Append to a range ...
+	if (cur->first + cur->second == base)
+	  {
+	    cur->second += n;
+	    // Maybe the next item on the list can be merged.
+	    free_list_type::iterator next = cur;
+	    ++next;
+	    if (next != fl.end() && next->first == end)
+	      {
+		cur->second += next->second;
+		fl.erase(next);
+	      }
+	    return;
+	  }
+	// ... or prepend to a range ...
+	if (cur->first == end)
+	  {
+	    cur->first -= n;
+	    cur->second += n;
+	    return;
+	  }
+	// ... or insert a new range.
+	if (cur->first > end)
+	  break;
+      }
+    fl.insert(cur, pos_lenght_pair(base, n));
+  }
+
+  std::ostream&
+  free_list::dump_free_list(std::ostream& os) const
+  {
+    free_list_type::const_iterator i;
+    for (i = fl.begin(); i != fl.end(); ++i)
+      os << "  (" << i->first << ", " << i->second << ")";
+    return os;
+  }
+
+}