Before this change, all automata would construct their own

dictionaries (map of BDD variables to LTL formulae).  This was
cumbersome, because to multiply two automata we had to build a
common dictionary (the union of the two LTL formula spaces), and
install wrappers to translate each automaton's BDD answers into
the common dictionary.  This translation, that had to be repeated
when several products were nested, was time consuming and was a
hindrance for some optimizations.
In the new scheme, all automata involved in a product must
share the same dictionary.  An empty dictionary should be
constructed by the user and passed to the automaton' constructors
as necessary.
This huge change removes most code than it adds.

* src/Makefile.am (libspot_la_LIBADD): Add misc/libmisc.la.
* src/misc/bddalloc.hh, src/misc/bddalloc.cc: New files.  These
partly replace src/tgba/bddfactory.hh and src/tgba/bddfactory.cc.
* src/misc/Makefile.am: Adjust to build bddalloc.hh and bddalloc.cc.
* src/tgba/bddfactory.hh, src/tgba/bddfactory.cc,
src/tgba/dictunion.hh, src/tgba/dictunion.cc,
src/tgba/tgbabdddict.hh, src/tgba/tgbabdddict.cc,
src/tgba/tgbabddtranslatefactory.hh,
src/tgba/tgbabddtranslatefactory.cc,
src/tgba/tgbatranslateproxy.hh, src/tgba/tgbatranslateproxy.cc:
Delete.
* src/tgba/bdddict.hh, src/tgba/bdddict.cc: New files.  These
replaces tgbabdddict.hh and tgbabdddict.cc, and also part of
bddfactory.hh and bddfactory.cc.
* src/tgba/bddprint.cc, src/tgba/bddprint.hh: Adjust to
use bdd_dict* instead of tgba_bdd_dict&.
* src/tgba/succiterconcrete.cc (succ_iter_concrete::next()):
Get next_to_now from the dictionary.
* src/tgba/tgba.hh (tgba::get_dict): Return a bdd_dict*,
not a const tgba_bdd_dict*.
* src/tgba/tgbabddconcrete.cc, src/tgba/tgbabddconcrete.hh:
Adjust to use the new dictionary, stored in data_.
* src/tgba/tgbabddconcretefactory.cc,
src/tgba/tgbabddconcretefactory.hh: Likewise.  Plus
now_to_next_ is now also stored in the dictionary.
* src/tgba/tgbabddconcreteproduct.cc: Likewise.  Now
that both operand share the same product, there is not
point in using tgba_bdd_translate_factory.
* src/tgba/tgbabddcoredata.cc, src/tgba/tgbabddcoredata.hh:
Store a bdd_dict (taken as constructor argument).
(tgba_bdd_core_data::~tgba_bdd_core_data): Remove.
(tgba_bdd_core_data::translate): Remove.
(tgba_bdd_core_data::next_to_now): Remove (now in dict).
(tgba_bdd_core_data::dict): New pointer.
* src/tgba/tgbabddfactory.hh: (tgba_bdd_factory::get_dict): Remove.
* src/tgba/tgbaexplicit.cc, src/tgba/tgbaexplicit.hh:
Adjust to use the new dictionary.
* src/tgba/tgbaproduct.cc, src/tgba/tgbaproduct.hh: Likewise.  Do
not use tgba_bdd_dict_union and tgba_bdd_translate_proxy anymore.
* src/tgbaalgos/lbtt.cc, src/tgbaalgos/save.cc: Adjust to
use bdd_dict* instead of tgba_bdd_dict&.
* src/tgbaalgos/ltl2tgba.cc, src/tgbaalgos/ltl2tgba.cc: Likewise.
(ltl_to_tgba): Take a dict argument.
* src/tgbaparse/public.hh (tgba_parse): Take a dict argument.
* src/tgbaparse/tgbaparse.yy (tgba_parse): Take a dict argument.
* src/tgbatest/explicit.cc, src/tgbatest/explprod.cc,
src/tgbatest/ltlprod.cc, src/tgbatest/mixprod.cc,
src/tgbatest/readsave.cc, src/tgbatest/spotlbtt.cc,
src/tgbatest/tgbaread.cc, src/tgbatest/tripprod.cc: Instantiate
a dictionary, and pass it to the automata' constructors.
* src/tgbatest/ltl2tgba.cc: Likewise, and remove the -o (defrag)
option.
* iface/gspn/gspn.hh (tgba_gspn::tgba_gspn): Take a bdd_dict argument.
(tgba_gspn::get_dict): Adjust return type.
* iface/gspn/gspn.cc: Do not use bdd_factory, adjust to
use the new dictionary instead.

src/misc/.cvsignore

@@ -1,3 +1,6 @@
 Makefile
 Makefile.in
 .deps
+.libs
+*.lo
+*.la

src/misc/Makefile.am

@@ -1,2 +1,12 @@
+AM_CPPFLAGS = -I$(srcdir)/.. $(BUDDY_CPPFLAGS)
+AM_CXXFLAGS = $(WARNING_CXXFLAGS)
+
 miscdir = $(pkgincludedir)/misc
-misc_HEADERS = const_sel.hh
+
+misc_HEADERS = \
+  bddalloc.hh \
+  const_sel.hh
+
+noinst_LTLIBRARIES = libmisc.la
+libmisc_la_SOURCES = \
+  bddalloc.cc

src/misc/bddalloc.cc

@@ -0,0 +1,123 @@
+#include <bdd.h>
+#include <cassert>
+#include "bddalloc.hh"
+
+namespace spot
+{
+  bool bdd_allocator::initialized = false;
+  int bdd_allocator::varnum = 2;
+
+  bdd_allocator::bdd_allocator()
+  {
+    initialize();
+    free_list.push_front(pos_lenght_pair(0, varnum));
+  }
+
+  void
+  bdd_allocator::initialize()
+  {
+    if (initialized)
+      return;
+    initialized = true;
+    bdd_init(50000, 5000);
+    bdd_setvarnum(varnum);
+  }
+
+  int
+  bdd_allocator::allocate_variables(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 = free_list.end();
+    free_list_type::iterator cur;
+    for (cur = free_list.begin(); cur != free_list.end(); ++cur)
+      {
+	if (cur->second < n)
+	  continue;
+	if (n == cur->second)
+	  {
+	    best = cur;
+	    break;
+	  }
+	if (best == free_list.end()
+	    || cur->second < best->second)
+	  best = cur;
+      }
+
+    // We have found enough free variables.
+    if (best != free_list.end())
+      {
+	int result = best->first;
+	best->second -= n;
+	assert(best->second >= 0);
+	// Erase the range if it's now empty.
+	if (best->second == 0)
+	  free_list.erase(best);
+	else
+	  best->first += n;
+	return result;
+      }
+
+    // We haven't found enough adjacent free variables;
+    // ask BuDDy for some more.
+
+    // If we already have some free variable at the end
+    // of the variable space, allocate just the difference.
+    if (free_list.size() > 0
+	&& free_list.back().first + free_list.back().second == varnum)
+      {
+	int res = free_list.back().first;
+	int endvar = free_list.back().second;
+	assert(n > endvar);
+	bdd_extvarnum(n - endvar);
+	varnum += n - endvar;
+	free_list.pop_back();
+	return res;
+      }
+    else
+      {
+	// Otherwise, allocate as much variables as we need.
+	int res = varnum;
+	bdd_extvarnum(n);
+	varnum += n;
+	return res;
+      }
+  }
+
+  void
+  bdd_allocator::release_variables(int base, int n)
+  {
+    free_list_type::iterator cur;
+    int end = base + n;
+    for (cur = free_list.begin(); cur != free_list.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 != free_list.end()
+		&& next->first == end)
+	      {
+		cur->second += next->second;
+		free_list.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;
+      }
+    free_list.insert(cur, pos_lenght_pair(base, n));
+  }
+}

src/misc/bddalloc.hh

@@ -0,0 +1,32 @@
+#ifndef SPOT_MISC_BDDALLOC_HH
+# define SPOT_MISC_BDDALLOC_HH
+
+#include <list>
+#include <utility>
+
+namespace spot
+{
+
+  /// Manage ranges of variables.
+  class bdd_allocator
+  {
+  protected:
+    /// Default constructor.
+    bdd_allocator();
+    /// Initialize the BDD library.
+    static void initialize();
+    /// Allocate \a n BDD variables.
+    int allocate_variables(int n);
+    /// Release \a n BDD variables starting at \a base.
+    void release_variables(int base, int n);
+
+    static bool initialized; ///< Whether the BDD library has been initialized.
+    static int varnum; ///< number of variable in use in the BDD library.
+    typedef std::pair<int, int> pos_lenght_pair;
+    typedef std::list<pos_lenght_pair> free_list_type;
+    free_list_type free_list; ///< Tracks unused BDD variables.
+  };
+
+}
+
+#endif // SPOT_MISC_BDDALLOC_HH