c++11: Replace boost::shared_ptr by std::shared_ptr.

* src/eltlparse/eltlparse.yy, src/ltlast/formula_tree.hh,
src/ltlast/nfa.hh, src/saba/sabastate.hh, src/tgba/state.hh: Here.

src/eltlparse/eltlparse.yy

@@ -32,7 +32,6 @@
 #include <limits>
 #include <cerrno>
 #include <algorithm>
-#include <boost/shared_ptr.hpp>
 #include "public.hh"
 #include "ltlast/allnodes.hh"
 #include "ltlast/formula_tree.hh"
@@ -376,9 +375,9 @@ nfa_arg: ARG
 	    CHECK_ARITY(@1, $1, $3->children.size(), arity);
 
 	    // Hack to return the right type without screwing with the
-	    // boost::shared_ptr memory handling by using get for
-	    // example. FIXME: Wait for the next version of boost and
-	    // modify the %union to handle formula_tree::node_ptr.
+	    // std::shared_ptr memory handling by using get for
+	    // example. FIXME: modify the %union to handle
+	    // formula_tree::node_ptr.
 	    formula_tree::node_unop* tmp1 = new formula_tree::node_unop;
 	    tmp1->op = unop::Not;
 	    tmp1->child = realias(i->second, $3->children);

src/ltlast/formula_tree.hh

@@ -24,7 +24,7 @@
 
 # include "formula.hh"
 # include <vector>
-# include <boost/shared_ptr.hpp>
+# include <memory>
 # include "multop.hh"
 # include "binop.hh"
 # include "unop.hh"
@@ -44,8 +44,7 @@ namespace spot
       {
 	virtual ~node() {};
       };
-      /// We use boost::shared_ptr to easily handle deletion.
-      typedef boost::shared_ptr<node> node_ptr;
+      typedef std::shared_ptr<node> node_ptr;
 
       struct SPOT_API node_unop : node
       {

src/ltlast/nfa.hh

@@ -24,7 +24,7 @@
 
 # include "misc/common.hh"
 # include "misc/hash.hh"
-# include <boost/shared_ptr.hpp>
+# include <memory>
 # include <list>
 # include <set>
 # include <map>
@@ -52,10 +52,10 @@ namespace spot
     public:
       struct transition;
       typedef std::list<transition*> state;
-      typedef boost::shared_ptr<formula_tree::node> label;
+      typedef std::shared_ptr<formula_tree::node> label;
       /// Iterator over the successors of a state.
       typedef succ_iterator iterator;
-      typedef boost::shared_ptr<nfa> ptr;
+      typedef std::shared_ptr<nfa> ptr;
 
       /// Explicit transitions.
       struct transition

src/saba/sabastate.hh

@@ -23,7 +23,8 @@
 #include "misc/common.hh"
 #include <bdd.h>
 #include <functional>
-#include <boost/shared_ptr.hpp>
+#include <memory>
+#include <cassert>
 
 namespace spot
 {
@@ -156,7 +157,7 @@ namespace spot
   // Functions related to shared_ptr.
   //////////////////////////////////////////////////
 
-  typedef boost::shared_ptr<const saba_state> shared_saba_state;
+  typedef std::shared_ptr<const saba_state> shared_saba_state;
 
   /// \ingroup saba_essentials
   /// \brief Strict Weak Ordering for \c shared_saba_state

src/tgba/state.hh

@@ -28,7 +28,7 @@
 #include <bdd.h>
 #include <cassert>
 #include <functional>
-#include <boost/shared_ptr.hpp>
+#include <memory>
 #include "misc/casts.hh"
 #include "misc/hash.hh"
 
@@ -179,7 +179,7 @@ namespace spot
   // Functions related to shared_ptr.
   //////////////////////////////////////////////////
 
-  typedef boost::shared_ptr<const state> shared_state;
+  typedef std::shared_ptr<const state> shared_state;
 
   inline void shared_state_deleter(state* s) { s->destroy(); }