* src/ltlvisit/clone.hh, src/ltlvisit/clone.cc: New files.

* src/ltlvisit/Makefile.am (libltlvisit_a_SOURCES): Add them.
* src/ltlvisit/lunabbrev.hh, src/ltlvisit/lunabbrev.cc: Inherit
from clone_visitor and remove all useless methods (now inherited).

src/ltlvisit/clone.cc

@@ -0,0 +1,74 @@
+#include "ltlast/allnodes.hh"
+#include "clone.hh"
+
+namespace spot 
+{
+  namespace ltl
+  {
+    clone_visitor::clone_visitor()
+    {
+    }
+
+    clone_visitor::~clone_visitor()
+    {
+    }
+
+    formula*
+    clone_visitor::result() const
+    {
+      return result_;
+    }
+    
+    void 
+    clone_visitor::visit(const atomic_prop* ap)
+    {
+      result_ = new atomic_prop(ap->name());
+    }
+
+    void 
+    clone_visitor::visit(const constant* c)
+    {
+      result_ = new constant(c->val());
+    }
+
+    void 
+    clone_visitor::visit(const unop* uo)
+    {
+      result_ = new unop(uo->op(), recurse(uo->child()));
+    }
+    
+    void 
+    clone_visitor::visit(const binop* bo)
+    {
+      result_ = new binop(bo->op(), 
+			  recurse(bo->first()), recurse(bo->second()));
+    }
+    
+    void 
+    clone_visitor::visit(const multop* mo)
+    {
+      multop* res = new multop(mo->op());
+      unsigned mos = mo->size();
+      for (unsigned i = 0; i < mos; ++i)
+	{
+	  res->add(recurse(mo->nth(i)));
+	}
+      result_ = res;
+    }
+
+    formula* 
+    clone_visitor::recurse(const formula* f)
+    {
+      return clone(f);
+    }
+
+    formula* 
+    clone(const formula* f)
+    {
+      clone_visitor v;
+      f->accept(v);
+      return v.result();
+    }
+
+  }
+}