boost::function & boost::bind 源码分析

时间:2020-11-29 04:42:29

boost::bind实现代码


//  参数存储

template<class A1> struct storage1
{
    explicit storage1( A1 a1 ): a1_( a1 ) {}


    template<class V> void accept(V & v) const
    {
        BOOST_BIND_VISIT_EACH(v, a1_, 0);
    }


    A1 a1_;
};
template<int I> struct storage1< boost::arg<I> >
{
    explicit storage1( boost::arg<I> ) {}


    template<class V> void accept(V &) const { }


    static boost::arg<I> a1_() { return boost::arg<I>(); }
};


template<int I> struct storage1< boost::arg<I> (*) () >
{
    explicit storage1( boost::arg<I> (*) () ) {}


    template<class V> void accept(V &) const { }


    static boost::arg<I> a1_() { return boost::arg<I>(); }
};


// 参数列表,(实参,占位符)
template< class A1 > class list1: private storage1< A1 > {
A1 operator[] (boost::arg<1>) const { return base_type::a1_; }
template<class T> T & operator[] (_bi::value<T> & v) const { return v.get(); }


    template<class R, class F, class A> R operator()(type<R>, F & f, A & a, long)
    {
        return unwrapper<F>::unwrap(f, 0)(a[base_type::a1_], a[base_type::a2_], a[base_type::a3_], a[base_type::a4_], a[base_type::a5_], a[base_type::a6_], a[base_type::a7_], a[base_type::a8_], a[base_type::a9_]);
    }


    template<class R, class F, class A> R operator()(type<R>, F const & f, A & a, long) const
    {
        return unwrapper<F const>::unwrap(f, 0)(a[base_type::a1_], a[base_type::a2_], a[base_type::a3_], a[base_type::a4_], a[base_type::a5_], a[base_type::a6_], a[base_type::a7_], a[base_type::a8_], a[base_type::a9_]);
    }
}


// bind对象
template<class R, class F, class L> class bind_t
{
public:


    typedef bind_t this_type;


    bind_t(F f, L const & l): f_(f), l_(l) {}


    result_type operator()()
    {
        list0 a;
        BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0);
    }


    result_type operator()() const
    {
        list0 a;
        BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0);
    }


    template<class A1> result_type operator()(A1 & a1)
    {
        list1<A1 &> a(a1);
        BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0);
    }


    template<class A1> result_type operator()(A1 & a1) const
    {
        list1<A1 &> a(a1);
        BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0);
    }


    ...


    template<class A1, class A2> result_type operator()(A1 & a1, A2 & a2 /*调用参数*/)
    {
        list2<A1 &, A2 &> a(a1, a2);
        BOOST_BIND_RETURN l_(type<result_type>(), f_, a, 0);
    }


    ...


private:


    F f_;  // 函数、仿函数
    L l_;  // bind的参数


};


// bind函数,参数自动推到
template<class F>
    _bi::bind_t<_bi::unspecified, F, _bi::list0>
    BOOST_BIND(F f)
{
    typedef _bi::list0 list_type;
    return _bi::bind_t<_bi::unspecified, F, list_type> (f, list_type());
}


template<class F, class A1>
    _bi::bind_t<_bi::unspecified, F, typename _bi::list_av_1<A1>::type>
    BOOST_BIND(F f, A1 a1)
{
    typedef typename _bi::list1<A1> list_type;
    return _bi::bind_t<_bi::unspecified, F, list_type> (f, list_type(a1));
}

boost::functor实现代码


// 仿函数管理器


      /**
       * A buffer used to store small function objects in
       * boost::function. It is a union containing function pointers,
       * object pointers, and a structure that resembles a bound
       * member function pointer.
       */


      // 仿函数buffer
      union function_buffer
      {
        // For pointers to function objects
        mutable void* obj_ptr;


        // For pointers to std::type_info objects
        struct type_t {
          // (get_functor_type_tag, check_functor_type_tag).
          const detail::sp_typeinfo* type;


          // Whether the type is const-qualified.
          bool const_qualified;
          // Whether the type is volatile-qualified.
          bool volatile_qualified;
        } type;


        // For function pointers of all kinds
        mutable void (*func_ptr)();


        // For bound member pointers
        struct bound_memfunc_ptr_t {
          void (X::*memfunc_ptr)(int);
          void* obj_ptr;
        } bound_memfunc_ptr;


        // For references to function objects. We explicitly keep
        // track of the cv-qualifiers on the object referenced.
        struct obj_ref_t {
          mutable void* obj_ptr;
          bool is_const_qualified;
          bool is_volatile_qualified;
        } obj_ref;


        // To relax aliasing constraints
        mutable char data;
      };


      // 仿函数管理器
      template<typename Functor>
      struct functor_manager
      {
      private:
        typedef Functor functor_type;


        // Function pointers
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, function_ptr_tag)
        {
          functor_manager_common<Functor>::manage_ptr(in_buffer,out_buffer,op);
        }


        // Function objects that fit in the small-object buffer.
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, mpl::true_)
        {
          functor_manager_common<Functor>::manage_small(in_buffer,out_buffer,op);
        }
        
        // Function objects that require heap allocation
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, mpl::false_)
        {
          if (op == clone_functor_tag) {
            // Clone the functor
            // GCC 2.95.3 gets the CV qualifiers wrong here, so we
            // can't do the static_cast that we should do.
            // jewillco: Changing this to static_cast because GCC 2.95.3 is
            // obsolete.
            const functor_type* f =
              static_cast<const functor_type*>(in_buffer.obj_ptr);
            functor_type* new_f = new functor_type(*f);
            out_buffer.obj_ptr = new_f;
          } else if (op == move_functor_tag) {
            out_buffer.obj_ptr = in_buffer.obj_ptr;
            in_buffer.obj_ptr = 0;
          } else if (op == destroy_functor_tag) {
            /* Cast from the void pointer to the functor pointer type */
            functor_type* f =
              static_cast<functor_type*>(out_buffer.obj_ptr);
            delete f;
            out_buffer.obj_ptr = 0;
          } else if (op == check_functor_type_tag) {
            const detail::sp_typeinfo& check_type
              = *out_buffer.type.type;
            if (BOOST_FUNCTION_COMPARE_TYPE_ID(check_type, BOOST_SP_TYPEID(Functor)))
              out_buffer.obj_ptr = in_buffer.obj_ptr;
            else
              out_buffer.obj_ptr = 0;
          } else /* op == get_functor_type_tag */ {
            out_buffer.type.type = &BOOST_SP_TYPEID(Functor);
            out_buffer.type.const_qualified = false;
            out_buffer.type.volatile_qualified = false;
          }
        }


        // For function objects, we determine whether the function
        // object can use the small-object optimization buffer or
        // whether we need to allocate it on the heap.
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, function_obj_tag)
        {
          manager(in_buffer, out_buffer, op,
                  mpl::bool_<(function_allows_small_object_optimization<functor_type>::value)>());
        }


        // For member pointers, we use the small-object optimization buffer.
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, member_ptr_tag)
        {
          manager(in_buffer, out_buffer, op, mpl::true_());
        }


      public:
        /* Dispatch to an appropriate manager based on whether we have a
           function pointer or a function object pointer. */
        static inline void
        manage(const function_buffer& in_buffer, function_buffer& out_buffer, 
               functor_manager_operation_type op)
        {
          typedef typename get_function_tag<functor_type>::type tag_type;
          switch (op) {
          case get_functor_type_tag:
            out_buffer.type.type = &BOOST_SP_TYPEID(functor_type);
            out_buffer.type.const_qualified = false;
            out_buffer.type.volatile_qualified = false;
            return;


          default:
            manager(in_buffer, out_buffer, op, tag_type());
            return;
          }
        }
      };
      // 仿函数管理器,带分配器
      template<typename Functor, typename Allocator>
      struct functor_manager_a
      {
      private:
        typedef Functor functor_type;


        // Function pointers
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, function_ptr_tag)
        {
          functor_manager_common<Functor>::manage_ptr(in_buffer,out_buffer,op);
        }


        // Function objects that fit in the small-object buffer.
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, mpl::true_)
        {
          functor_manager_common<Functor>::manage_small(in_buffer,out_buffer,op);
        }
        
        // Function objects that require heap allocation
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, mpl::false_)
        {
          typedef functor_wrapper<Functor,Allocator> functor_wrapper_type;
          typedef typename Allocator::template rebind<functor_wrapper_type>::other
            wrapper_allocator_type;
          typedef typename wrapper_allocator_type::pointer wrapper_allocator_pointer_type;


          if (op == clone_functor_tag) {
            // Clone the functor
            // GCC 2.95.3 gets the CV qualifiers wrong here, so we
            // can't do the static_cast that we should do.
            const functor_wrapper_type* f =
              static_cast<const functor_wrapper_type*>(in_buffer.obj_ptr);
            wrapper_allocator_type wrapper_allocator(static_cast<Allocator const &>(*f));
            wrapper_allocator_pointer_type copy = wrapper_allocator.allocate(1);
            wrapper_allocator.construct(copy, *f);


            // Get back to the original pointer type
            functor_wrapper_type* new_f = static_cast<functor_wrapper_type*>(copy);
            out_buffer.obj_ptr = new_f;
          } else if (op == move_functor_tag) {
            out_buffer.obj_ptr = in_buffer.obj_ptr;
            in_buffer.obj_ptr = 0;
          } else if (op == destroy_functor_tag) {
            /* Cast from the void pointer to the functor_wrapper_type */
            functor_wrapper_type* victim =
              static_cast<functor_wrapper_type*>(in_buffer.obj_ptr);
            wrapper_allocator_type wrapper_allocator(static_cast<Allocator const &>(*victim));
            wrapper_allocator.destroy(victim);
            wrapper_allocator.deallocate(victim,1);
            out_buffer.obj_ptr = 0;
          } else if (op == check_functor_type_tag) {
            const detail::sp_typeinfo& check_type 
              = *out_buffer.type.type;
            if (BOOST_FUNCTION_COMPARE_TYPE_ID(check_type, BOOST_SP_TYPEID(Functor)))
              out_buffer.obj_ptr = in_buffer.obj_ptr;
            else
              out_buffer.obj_ptr = 0;
          } else /* op == get_functor_type_tag */ {
            out_buffer.type.type = &BOOST_SP_TYPEID(Functor);
            out_buffer.type.const_qualified = false;
            out_buffer.type.volatile_qualified = false;
          }
        }


        // For function objects, we determine whether the function
        // object can use the small-object optimization buffer or
        // whether we need to allocate it on the heap.
        static inline void
        manager(const function_buffer& in_buffer, function_buffer& out_buffer, 
                functor_manager_operation_type op, function_obj_tag)
        {
          manager(in_buffer, out_buffer, op,
                  mpl::bool_<(function_allows_small_object_optimization<functor_type>::value)>());
        }


      public:
        /* Dispatch to an appropriate manager based on whether we have a
           function pointer or a function object pointer. */
        static inline void
        manage(const function_buffer& in_buffer, function_buffer& out_buffer, 
               functor_manager_operation_type op)
        {
          typedef typename get_function_tag<functor_type>::type tag_type;
          switch (op) {
          case get_functor_type_tag:
            out_buffer.type.type = &BOOST_SP_TYPEID(functor_type);
            out_buffer.type.const_qualified = false;
            out_buffer.type.volatile_qualified = false;
            return;


          default:
            manager(in_buffer, out_buffer, op, tag_type());
            return;
          }
        }
      };
      // 虚表
      struct vtable_base
      {
        void (*manager)(const function_buffer& in_buffer, 
                        function_buffer& out_buffer, 
                        functor_manager_operation_type op);
      };




class function_base
{
public:
  function_base() : vtable(0) { }


  /** Determine if the function is empty (i.e., has no target). */
  bool empty() const { return !vtable; }


  /** Retrieve the type of the stored function object, or BOOST_SP_TYPEID(void)
      if this is empty. */
  const detail::sp_typeinfo& target_type() const
  {
    if (!vtable) return BOOST_SP_TYPEID(void);


    detail::function::function_buffer type;
    get_vtable()->manager(functor, type, detail::function::get_functor_type_tag);
    return *type.type.type;
  }


  template<typename Functor>
    Functor* target()
    {
      if (!vtable) return 0;


      detail::function::function_buffer type_result;
      type_result.type.type = &BOOST_SP_TYPEID(Functor);
      type_result.type.const_qualified = is_const<Functor>::value;
      type_result.type.volatile_qualified = is_volatile<Functor>::value;
      get_vtable()->manager(functor, type_result, 
                      detail::function::check_functor_type_tag);
      return static_cast<Functor*>(type_result.obj_ptr);
    }


  template<typename Functor>
#if defined(BOOST_MSVC) && BOOST_WORKAROUND(BOOST_MSVC, < 1300)
    const Functor* target( Functor * = 0 ) const
#else
    const Functor* target() const
#endif
    {
      if (!vtable) return 0;


      detail::function::function_buffer type_result;
      type_result.type.type = &BOOST_SP_TYPEID(Functor);
      type_result.type.const_qualified = true;
      type_result.type.volatile_qualified = is_volatile<Functor>::value;
      get_vtable()->manager(functor, type_result, 
                      detail::function::check_functor_type_tag);
      // GCC 2.95.3 gets the CV qualifiers wrong here, so we
      // can't do the static_cast that we should do.
      return static_cast<const Functor*>(type_result.obj_ptr);
    }


  template<typename F>
    bool contains(const F& f) const
    {
#if defined(BOOST_MSVC) && BOOST_WORKAROUND(BOOST_MSVC, < 1300)
      if (const F* fp = this->target( (F*)0 ))
#else
      if (const F* fp = this->template target<F>())
#endif
      {
        return function_equal(*fp, f);
      } else {
        return false;
      }
    }


#if defined(__GNUC__) && __GNUC__ == 3 && __GNUC_MINOR__ <= 3
  // GCC 3.3 and newer cannot copy with the global operator==, due to
  // problems with instantiation of function return types before it
  // has been verified that the argument types match up.
  template<typename Functor>
    BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool)
    operator==(Functor g) const
    {
      if (const Functor* fp = target<Functor>())
        return function_equal(*fp, g);
      else return false;
    }


  template<typename Functor>
    BOOST_FUNCTION_ENABLE_IF_NOT_INTEGRAL(Functor, bool)
    operator!=(Functor g) const
    {
      if (const Functor* fp = target<Functor>())
        return !function_equal(*fp, g);
      else return true;
    }
#endif


public: // should be protected, but GCC 2.95.3 will fail to allow access
  detail::function::vtable_base* get_vtable() const {
    return reinterpret_cast<detail::function::vtable_base*>(
             reinterpret_cast<std::size_t>(vtable) & ~static_cast<std::size_t>(0x01));
  }


  bool has_trivial_copy_and_destroy() const {
    return reinterpret_cast<std::size_t>(vtable) & 0x01;
  }


  detail::function::vtable_base* vtable;
  mutable detail::function::function_buffer functor;
};




      template<
        typename FunctionPtr,
        typename R BOOST_FUNCTION_COMMA
        BOOST_FUNCTION_TEMPLATE_PARMS
        >
      struct BOOST_FUNCTION_FUNCTION_INVOKER
      {
        static R invoke(function_buffer& function_ptr BOOST_FUNCTION_COMMA
                        BOOST_FUNCTION_PARMS)
        {
          FunctionPtr f = reinterpret_cast<FunctionPtr>(function_ptr.func_ptr);
          return f(BOOST_FUNCTION_ARGS);
        }
      };
      template<
        typename FunctionObj,
        typename R BOOST_FUNCTION_COMMA
        BOOST_FUNCTION_TEMPLATE_PARMS
      >
      struct BOOST_FUNCTION_VOID_FUNCTION_OBJ_INVOKER
      {
        static BOOST_FUNCTION_VOID_RETURN_TYPE
        invoke(function_buffer& function_obj_ptr BOOST_FUNCTION_COMMA
               BOOST_FUNCTION_PARMS)


        {
          FunctionObj* f;
          if (function_allows_small_object_optimization<FunctionObj>::value)
            f = reinterpret_cast<FunctionObj*>(&function_obj_ptr.data);
          else
            f = reinterpret_cast<FunctionObj*>(function_obj_ptr.obj_ptr);
          BOOST_FUNCTION_RETURN((*f)(BOOST_FUNCTION_ARGS));
        }
      };






  template<
    typename R BOOST_FUNCTION_COMMA
    BOOST_FUNCTION_TEMPLATE_PARMS
  >
  class BOOST_FUNCTION_FUNCTION : public function_base


#if BOOST_FUNCTION_NUM_ARGS == 1


    , public std::unary_function<T0,R>


#elif BOOST_FUNCTION_NUM_ARGS == 2


    , public std::binary_function<T0,T1,R>


#endif


  {
  public:
#ifndef BOOST_NO_VOID_RETURNS
    typedef R         result_type;
#else
    typedef  typename boost::detail::function::function_return_type<R>::type
      result_type;
#endif // BOOST_NO_VOID_RETURNS


  private:
    typedef boost::detail::function::BOOST_FUNCTION_VTABLE<
              R BOOST_FUNCTION_COMMA BOOST_FUNCTION_TEMPLATE_ARGS>
      vtable_type;


    vtable_type* get_vtable() const {
      return reinterpret_cast<vtable_type*>(
               reinterpret_cast<std::size_t>(vtable) & ~static_cast<size_t>(0x01));
    }


    struct clear_type {};


  public:
    BOOST_STATIC_CONSTANT(int, args = BOOST_FUNCTION_NUM_ARGS);


    // add signature for boost::lambda
    template<typename Args>
    struct sig
    {
      typedef result_type type;
    };


#if BOOST_FUNCTION_NUM_ARGS == 1
    typedef T0 argument_type;
#elif BOOST_FUNCTION_NUM_ARGS == 2
    typedef T0 first_argument_type;
    typedef T1 second_argument_type;
#endif


    BOOST_STATIC_CONSTANT(int, arity = BOOST_FUNCTION_NUM_ARGS);
    BOOST_FUNCTION_ARG_TYPES


    typedef BOOST_FUNCTION_FUNCTION self_type;


    BOOST_FUNCTION_FUNCTION() : function_base() { }


    // MSVC chokes if the following two constructors are collapsed into
    // one with a default parameter.
    template<typename Functor>
    BOOST_FUNCTION_FUNCTION(Functor BOOST_FUNCTION_TARGET_FIX(const &) f
#ifndef BOOST_NO_SFINAE
                            ,typename enable_if_c<
                            (boost::type_traits::ice_not<
                             (is_integral<Functor>::value)>::value),
                                        int>::type = 0
#endif // BOOST_NO_SFINAE
                            ) :
      function_base()
    {
      this->assign_to(f);
    }
    template<typename Functor,typename Allocator>
    BOOST_FUNCTION_FUNCTION(Functor BOOST_FUNCTION_TARGET_FIX(const &) f, Allocator a
#ifndef BOOST_NO_SFINAE
                            ,typename enable_if_c<
                            (boost::type_traits::ice_not<
                             (is_integral<Functor>::value)>::value),
                                        int>::type = 0
#endif // BOOST_NO_SFINAE
                            ) :
      function_base()
    {
      this->assign_to_a(f,a);
    }


#ifndef BOOST_NO_SFINAE
    BOOST_FUNCTION_FUNCTION(clear_type*) : function_base() { }
#else
    BOOST_FUNCTION_FUNCTION(int zero) : function_base()
    {
      BOOST_ASSERT(zero == 0);
    }
#endif


    BOOST_FUNCTION_FUNCTION(const BOOST_FUNCTION_FUNCTION& f) : function_base()
    {
      this->assign_to_own(f);
    }


    ~BOOST_FUNCTION_FUNCTION() { clear(); }


    result_type operator()(BOOST_FUNCTION_PARMS) const
    {
      if (this->empty())
        boost::throw_exception(bad_function_call());


      return get_vtable()->invoker
               (this->functor BOOST_FUNCTION_COMMA BOOST_FUNCTION_ARGS);
    }


    // The distinction between when to use BOOST_FUNCTION_FUNCTION and
    // when to use self_type is obnoxious. MSVC cannot handle self_type as
    // the return type of these assignment operators, but Borland C++ cannot
    // handle BOOST_FUNCTION_FUNCTION as the type of the temporary to
    // construct.
    template<typename Functor>
#ifndef BOOST_NO_SFINAE
    typename enable_if_c<
               (boost::type_traits::ice_not<
                 (is_integral<Functor>::value)>::value),
               BOOST_FUNCTION_FUNCTION&>::type
#else
    BOOST_FUNCTION_FUNCTION&
#endif
    operator=(Functor BOOST_FUNCTION_TARGET_FIX(const &) f)
    {
      this->clear();
      BOOST_TRY  {
        this->assign_to(f);
      } BOOST_CATCH (...) {
        vtable = 0;
        BOOST_RETHROW;
      }
      BOOST_CATCH_END
      return *this;
    }
    template<typename Functor,typename Allocator>
    void assign(Functor BOOST_FUNCTION_TARGET_FIX(const &) f, Allocator a)
    {
      this->clear();
      BOOST_TRY{
        this->assign_to_a(f,a);
      } BOOST_CATCH (...) {
        vtable = 0;
        BOOST_RETHROW;
      }
      BOOST_CATCH_END
    }


#ifndef BOOST_NO_SFINAE
    BOOST_FUNCTION_FUNCTION& operator=(clear_type*)
    {
      this->clear();
      return *this;
    }
#else
    BOOST_FUNCTION_FUNCTION& operator=(int zero)
    {
      BOOST_ASSERT(zero == 0);
      this->clear();
      return *this;
    }
#endif


    // Assignment from another BOOST_FUNCTION_FUNCTION
    BOOST_FUNCTION_FUNCTION& operator=(const BOOST_FUNCTION_FUNCTION& f)
    {
      if (&f == this)
        return *this;


      this->clear();
      BOOST_TRY {
        this->assign_to_own(f);
      } BOOST_CATCH (...) {
        vtable = 0;
        BOOST_RETHROW;
      }
      BOOST_CATCH_END
      return *this;
    }


    void swap(BOOST_FUNCTION_FUNCTION& other)
    {
      if (&other == this)
        return;


      BOOST_FUNCTION_FUNCTION tmp;
      tmp.move_assign(*this);
      this->move_assign(other);
      other.move_assign(tmp);
    }


    // Clear out a target, if there is one
    void clear()
    {
      if (vtable) {
        if (!this->has_trivial_copy_and_destroy())
          get_vtable()->clear(this->functor);
        vtable = 0;
      }
    }


#if (defined __SUNPRO_CC) && (__SUNPRO_CC <= 0x530) && !(defined BOOST_NO_COMPILER_CONFIG)
    // Sun C++ 5.3 can't handle the safe_bool idiom, so don't use it
    operator bool () const { return !this->empty(); }
#else
  private:
    struct dummy {
      void nonnull() {}
    };


    typedef void (dummy::*safe_bool)();


  public:
    operator safe_bool () const
      { return (this->empty())? 0 : &dummy::nonnull; }


    bool operator!() const
      { return this->empty(); }
#endif


  private:
    void assign_to_own(const BOOST_FUNCTION_FUNCTION& f)
    {
      if (!f.empty()) {
        this->vtable = f.vtable;
        if (this->has_trivial_copy_and_destroy())
          this->functor = f.functor;
        else
          get_vtable()->base.manager(f.functor, this->functor,
                                     boost::detail::function::clone_functor_tag);
      }
    }


    template<typename Functor>
    void assign_to(Functor f)
    {
      using detail::function::vtable_base;


      typedef typename detail::function::get_function_tag<Functor>::type tag;
      typedef detail::function::BOOST_FUNCTION_GET_INVOKER<tag> get_invoker;
      /*
      template<typename Tag>
      struct BOOST_FUNCTION_GET_INVOKER { };


      template<>
      struct BOOST_FUNCTION_GET_INVOKER<function_ptr_tag>
      {
        template<typename FunctionPtr,
                 typename R BOOST_FUNCTION_COMMA BOOST_FUNCTION_TEMPLATE_PARMS>
        struct apply
        {
          typedef typename BOOST_FUNCTION_GET_FUNCTION_INVOKER<
                             FunctionPtr,
                             R BOOST_FUNCTION_COMMA
                             BOOST_FUNCTION_TEMPLATE_ARGS
                           >::type
            invoker_type;


          typedef functor_manager<FunctionPtr> manager_type;
        };


        template<typename FunctionPtr,
                 typename R BOOST_FUNCTION_COMMA BOOST_FUNCTION_TEMPLATE_PARMS,
                 typename Allocator>
        struct apply_a
        {
          typedef typename BOOST_FUNCTION_GET_FUNCTION_INVOKER<
                             FunctionPtr,
                             R BOOST_FUNCTION_COMMA
                             BOOST_FUNCTION_TEMPLATE_ARGS
                           >::type
            invoker_type;


          typedef functor_manager<FunctionPtr> manager_type;
        };
      };


      template<
        typename FunctionPtr,
        typename R BOOST_FUNCTION_COMMA
        BOOST_FUNCTION_TEMPLATE_PARMS
      >
      struct BOOST_FUNCTION_GET_FUNCTION_INVOKER
      {
        typedef typename mpl::if_c<(is_void<R>::value),
                            BOOST_FUNCTION_VOID_FUNCTION_INVOKER<
                            FunctionPtr,
                            R BOOST_FUNCTION_COMMA
                            BOOST_FUNCTION_TEMPLATE_ARGS
                          >,
                          BOOST_FUNCTION_FUNCTION_INVOKER<
                            FunctionPtr,
                            R BOOST_FUNCTION_COMMA
                            BOOST_FUNCTION_TEMPLATE_ARGS
                          >
                       >::type type;
      };
      */
      typedef typename get_invoker::
                         template apply<Functor, R BOOST_FUNCTION_COMMA 
                        BOOST_FUNCTION_TEMPLATE_ARGS>
        handler_type;
      
      typedef typename handler_type::invoker_type invoker_type;
      typedef typename handler_type::manager_type manager_type;


      // Note: it is extremely important that this initialization use
      // static initialization. Otherwise, we will have a race
      // condition here in multi-threaded code. See
      // http://thread.gmane.org/gmane.comp.lib.boost.devel/164902/.
      static const vtable_type stored_vtable = 
        { { &manager_type::manage }, &invoker_type::invoke };


      if (stored_vtable.assign_to(f, functor)) {
        std::size_t value = reinterpret_cast<std::size_t>(&stored_vtable.base);
        if (boost::has_trivial_copy_constructor<Functor>::value &&
            boost::has_trivial_destructor<Functor>::value &&
            detail::function::function_allows_small_object_optimization<Functor>::value)
          value |= static_cast<size_t>(0x01);
        vtable = reinterpret_cast<detail::function::vtable_base *>(value);
      } else 
        vtable = 0;
    }


    template<typename Functor,typename Allocator>
    void assign_to_a(Functor f,Allocator a)
    {
      using detail::function::vtable_base;


      typedef typename detail::function::get_function_tag<Functor>::type tag;
      typedef detail::function::BOOST_FUNCTION_GET_INVOKER<tag> get_invoker;
      typedef typename get_invoker::
                         template apply_a<Functor, R BOOST_FUNCTION_COMMA 
                         BOOST_FUNCTION_TEMPLATE_ARGS,
                         Allocator>
        handler_type;
      
      typedef typename handler_type::invoker_type invoker_type;
      typedef typename handler_type::manager_type manager_type;


      // Note: it is extremely important that this initialization use
      // static initialization. Otherwise, we will have a race
      // condition here in multi-threaded code. See
      // http://thread.gmane.org/gmane.comp.lib.boost.devel/164902/.
      static const vtable_type stored_vtable =
        { { &manager_type::manage }, &invoker_type::invoke };


      if (stored_vtable.assign_to_a(f, functor, a)) { 
        std::size_t value = reinterpret_cast<std::size_t>(&stored_vtable.base);
        if (boost::has_trivial_copy_constructor<Functor>::value &&
            boost::has_trivial_destructor<Functor>::value &&
            detail::function::function_allows_small_object_optimization<Functor>::value)
          value |= static_cast<std::size_t>(0x01);
        vtable = reinterpret_cast<detail::function::vtable_base *>(value);
      } else 
        vtable = 0;
    }


    // Moves the value from the specified argument to *this. If the argument 
    // has its function object allocated on the heap, move_assign will pass 
    // its buffer to *this, and set the argument's buffer pointer to NULL. 
    void move_assign(BOOST_FUNCTION_FUNCTION& f) 
    { 
      if (&f == this)
        return;


      BOOST_TRY {
        if (!f.empty()) {
          this->vtable = f.vtable;
          if (this->has_trivial_copy_and_destroy())
            this->functor = f.functor;
          else
            get_vtable()->base.manager(f.functor, this->functor,
                                     boost::detail::function::move_functor_tag);
          f.vtable = 0;
        } else {
          clear();
        }
      } BOOST_CATCH (...) {
        vtable = 0;
        BOOST_RETHROW;
      }
      BOOST_CATCH_END
    }
  };
  
  
  
  
  
      /**
       * vtable for a specific boost::function instance. This
       * structure must be an aggregate so that we can use static
       * initialization in boost::function's assign_to and assign_to_a
       * members. It therefore cannot have any constructors,
       * destructors, base classes, etc.
       */
      template<typename R BOOST_FUNCTION_COMMA BOOST_FUNCTION_TEMPLATE_PARMS>
      struct BOOST_FUNCTION_VTABLE
      {
#ifndef BOOST_NO_VOID_RETURNS
        typedef R         result_type;
#else
        typedef typename function_return_type<R>::type result_type;
#endif // BOOST_NO_VOID_RETURNS


        typedef result_type (*invoker_type)(function_buffer&
                                            BOOST_FUNCTION_COMMA
                                            BOOST_FUNCTION_TEMPLATE_ARGS);


        template<typename F>
        bool assign_to(F f, function_buffer& functor) const
        {
          typedef typename get_function_tag<F>::type tag;
          return assign_to(f, functor, tag());
        }
        template<typename F,typename Allocator>
        bool assign_to_a(F f, function_buffer& functor, Allocator a) const
        {
          typedef typename get_function_tag<F>::type tag;
          return assign_to_a(f, functor, a, tag());
        }


        void clear(function_buffer& functor) const
        {
          if (base.manager)
            base.manager(functor, functor, destroy_functor_tag);
        }


      private:
        // Function pointers
        template<typename FunctionPtr>
        bool 
        assign_to(FunctionPtr f, function_buffer& functor, function_ptr_tag) const
        {
          this->clear(functor);
          if (f) {
            // should be a reinterpret cast, but some compilers insist
            // on giving cv-qualifiers to free functions
            functor.func_ptr = reinterpret_cast<void (*)()>(f);
            return true;
          } else {
            return false;
          }
        }
        template<typename FunctionPtr,typename Allocator>
        bool 
        assign_to_a(FunctionPtr f, function_buffer& functor, Allocator, function_ptr_tag) const
        {
          return assign_to(f,functor,function_ptr_tag());
        }


        // Member pointers
#if BOOST_FUNCTION_NUM_ARGS > 0
        template<typename MemberPtr>
        bool assign_to(MemberPtr f, function_buffer& functor, member_ptr_tag) const
        {
          // DPG TBD: Add explicit support for member function
          // objects, so we invoke through mem_fn() but we retain the
          // right target_type() values.
          if (f) {
            this->assign_to(boost::mem_fn(f), functor);
            return true;
          } else {
            return false;
          }
        }
        template<typename MemberPtr,typename Allocator>
        bool assign_to_a(MemberPtr f, function_buffer& functor, Allocator a, member_ptr_tag) const
        {
          // DPG TBD: Add explicit support for member function
          // objects, so we invoke through mem_fn() but we retain the
          // right target_type() values.
          if (f) {
            this->assign_to_a(boost::mem_fn(f), functor, a);
            return true;
          } else {
            return false;
          }
        }
#endif // BOOST_FUNCTION_NUM_ARGS > 0


        // Function objects
        // Assign to a function object using the small object optimization
        template<typename FunctionObj>
        void 
        assign_functor(FunctionObj f, function_buffer& functor, mpl::true_) const
        {
          new (reinterpret_cast<void*>(&functor.data)) FunctionObj(f);
        }
        template<typename FunctionObj,typename Allocator>
        void 
        assign_functor_a(FunctionObj f, function_buffer& functor, Allocator, mpl::true_) const
        {
          assign_functor(f,functor,mpl::true_());
        }


        // Assign to a function object allocated on the heap.
        template<typename FunctionObj>
        void 
        assign_functor(FunctionObj f, function_buffer& functor, mpl::false_) const
        {
          functor.obj_ptr = new FunctionObj(f);
        }
        template<typename FunctionObj,typename Allocator>
        void 
        assign_functor_a(FunctionObj f, function_buffer& functor, Allocator a, mpl::false_) const
        {
          typedef functor_wrapper<FunctionObj,Allocator> functor_wrapper_type;
          typedef typename Allocator::template rebind<functor_wrapper_type>::other
            wrapper_allocator_type;
          typedef typename wrapper_allocator_type::pointer wrapper_allocator_pointer_type;
          wrapper_allocator_type wrapper_allocator(a);
          wrapper_allocator_pointer_type copy = wrapper_allocator.allocate(1);
          wrapper_allocator.construct(copy, functor_wrapper_type(f,a));
          functor_wrapper_type* new_f = static_cast<functor_wrapper_type*>(copy);
          functor.obj_ptr = new_f;
        }


        template<typename FunctionObj>
        bool 
        assign_to(FunctionObj f, function_buffer& functor, function_obj_tag) const
        {
          if (!boost::detail::function::has_empty_target(boost::addressof(f))) {
            assign_functor(f, functor, 
                           mpl::bool_<(function_allows_small_object_optimization<FunctionObj>::value)>());
            return true;
          } else {
            return false;
          }
        }
        template<typename FunctionObj,typename Allocator>
        bool 
        assign_to_a(FunctionObj f, function_buffer& functor, Allocator a, function_obj_tag) const
        {
          if (!boost::detail::function::has_empty_target(boost::addressof(f))) {
            assign_functor_a(f, functor, a,
                           mpl::bool_<(function_allows_small_object_optimization<FunctionObj>::value)>());
            return true;
          } else {
            return false;
          }
        }


        // Reference to a function object
        template<typename FunctionObj>
        bool 
        assign_to(const reference_wrapper<FunctionObj>& f, 
                  function_buffer& functor, function_obj_ref_tag) const
        {
          functor.obj_ref.obj_ptr = (void *)(f.get_pointer());
          functor.obj_ref.is_const_qualified = is_const<FunctionObj>::value;
          functor.obj_ref.is_volatile_qualified = is_volatile<FunctionObj>::value;
          return true;
        }
        template<typename FunctionObj,typename Allocator>
        bool 
        assign_to_a(const reference_wrapper<FunctionObj>& f, 
                  function_buffer& functor, Allocator, function_obj_ref_tag) const
        {
          return assign_to(f,functor,function_obj_ref_tag());
        }


      public:
        vtable_base base;
        invoker_type invoker;
      };

 

测试代码

/***
#include "stdafx.h"
#include <iostream>
#include <string>


class InvokeBase {
public:
    virtual void invoke() = 0;
};


template<class T>
class Invoke : public InvokeBase {
public:
    Invoke(T& functor) : m_functor(functor) {}


    virtual void invoke() {
        m_functor();
    }
    T&  m_functor;
};


class TestFunction {
public:
    template<class T>
    TestFunction(T& f) {
        m_f = new Invoke<T>(f);
    }


    ~TestFunction() {
        if (m_f) {
            delete m_f;
        }
    }


    void operator()() {
        m_f->invoke();
    }


private:
    InvokeBase*  m_f;
};


template<class T> void invokeType(void* funObj) {
    (*((T*)funObj))();
}


class TestFunction1 {
public:
    typedef void (*invoke_type)(void*);
    template<class T>
    TestFunction1(T& f) {
        m_f = invokeType<T>;
        m_funObj = new T(f);
    }




    void operator()() {
        m_f(m_funObj);
    }


private:
    invoke_type  m_f;
    void*        m_funObj;
};


class Test1 {
public:
    void operator()() {
        std::cout << "test1 " << std::endl;
    }
};


class Test2 {
public:
    void operator()() {
        std::cout << "test2" <<std::endl;
    }
};


void testF() {
    std::cout << "testF" <<std::endl;
}




int _tmain(int argc, _TCHAR* argv[])
{
    Test1  tt1;
    TestFunction1  ft1(tt1);
    ft1();


    Test1  t1;
    Test2  t2;
    TestFunction f1(t1), f2(t2), f3(testF);
    f1();
    f2();
    f3();


    f2 = f1;


    f1();
    f2();
return 0;
}
*/