gcc/testsuite/g++.dg/cpp0x/variadic-bind.C - gcc - Git at Google

 // { dg-do run { target c++11 } }
 // A basic implementation of TR1's bind using variadic teplates
 // Contributed by Douglas Gregor <doug.gregor@gmail.com>
 #include <cassert>

 // Trivial reference_wrapper
 template<typename T>
 struct reference_wrapper
 {
   reference_wrapper(T& x) : ptr(&x) { }

   operator T&() const { return *ptr; }

   T& get() const { return *ptr; }

   T* ptr;
 };

 template<typename T> reference_wrapper<T> ref(T& x) { return x; }
 template<typename T> reference_wrapper<const T> cref(const T& x) { return x; }

 // Simple type-traits we'll need
 template<typename T>
 struct add_reference
 {
   typedef T& type;
 };

 template<typename T>
 struct add_reference<T&>
 {
   typedef T& type;
 };

 template<typename T, typename U>
 struct is_same
 {
   static const bool value = false;
 };

 template<typename T>
 struct is_same<T, T>
 {
   static const bool value = true;
 };

 // For creating the constructor parameters of tuple<>
 template<typename T>
 struct add_const_reference
 {
   typedef const T& type;
 };

 template<typename T>
 struct add_const_reference<T&>
 {
   typedef T& type;
 };

 // 6.1.3 Class template tuple: Needed for bind() implementation
 template<typename... Values>
 class tuple;

 template<> class tuple<> { };

 template<typename Head, typename... Tail>
 class tuple<Head, Tail...>
   : private tuple<Tail...>
 {
   typedef tuple<Tail...> inherited;

  public:
   tuple() { }

   // implicit copy-constructor is okay

   tuple(typename add_const_reference<Head>::type v,
         typename add_const_reference<Tail>::type... vtail)
     : m_head(v), inherited(vtail...) { }

   template<typename... VValues>
   tuple(const tuple<VValues...>& other)
     : m_head(other.head()), inherited(other.tail()) { }

   template<typename... VValues>
   tuple& operator=(const tuple<VValues...>& other)
   {
     m_head = other.head();
     tail() = other.tail();
     return *this;
   }

   typename add_reference<Head>::type       head()       { return m_head; }
   typename add_reference<const Head>::type head() const { return m_head; }
   inherited&                               tail()       { return *this; }
   const inherited&                         tail() const { return *this; }

  protected:
   Head m_head;
 };

 template<typename T>
 struct make_tuple_result
 {
   typedef T type;
 };

 template<typename T>
 struct make_tuple_result<reference_wrapper<T> >
 {
   typedef T& type;
 };

 // 6.1.3.2 Tuple creation functions
 struct ignore_t {
   template<typename T> ignore_t& operator=(const T&) { return *this; }
 } ignore;

 template<typename... Values>
 tuple<typename make_tuple_result<Values>::type...>
 make_tuple(const Values&... values)
 {
   return tuple<typename make_tuple_result<Values>::type...>(values...);
 }

 template<typename... Values>
 tuple<Values&...> tie(Values&... values)
 {
   return tuple<Values&...>(values...);
 }

 // 6.1.3.3 Tuple helper classes
 template<typename Tuple>
 struct tuple_size;

 template<>
 struct tuple_size<tuple<> >
 {
   static const __SIZE_TYPE__ value = 0;
 };

 template<typename Head, typename... Tail>
 struct tuple_size<tuple<Head, Tail...> >
 {
   static const __SIZE_TYPE__ value = 1 + tuple_size<tuple<Tail...> >::value;
 };

 template<int I, typename Tuple>
 struct tuple_element;

 template<int I, typename Head, typename... Tail>
 struct tuple_element<I, tuple<Head, Tail...> >
 {
   typedef typename tuple_element<I-1, tuple<Tail...> >::type type;
 };

 template<typename Head, typename... Tail>
 struct tuple_element<0, tuple<Head, Tail...> >
 {
   typedef Head type;
 };

 // 6.1.3.4 Element access
 template<int I, typename Tuple>
 class get_impl;

 template<int I, typename Head, typename... Values>
 class get_impl<I, tuple<Head, Values...> >
 {
   typedef typename tuple_element<I-1, tuple<Values...> >::type Element;
   typedef typename add_reference<Element>::type RJ;
   typedef typename add_const_reference<Element>::type PJ;
   typedef get_impl<I-1, tuple<Values...> > Next;

  public:
   static RJ get(tuple<Head, Values...>& t)
   { return Next::get(t.tail()); }

   static PJ get(const tuple<Head, Values...>& t)
   { return Next::get(t.tail()); }
 };

 template<typename Head, typename... Values>
 class get_impl<0, tuple<Head, Values...> >
 {
   typedef typename add_reference<Head>::type RJ;
   typedef typename add_const_reference<Head>::type PJ;

  public:
   static RJ get(tuple<Head, Values...>& t)       { return t.head(); }
   static PJ get(const tuple<Head, Values...>& t) { return t.head(); }
 };

 template<int I, typename... Values>
 typename add_reference<
            typename tuple_element<I, tuple<Values...> >::type
          >::type
 get(tuple<Values...>& t)
 {
   return get_impl<I, tuple<Values...> >::get(t);
 }

 template<int I, typename... Values>
 typename add_const_reference<
            typename tuple_element<I, tuple<Values...> >::type
          >::type
 get(const tuple<Values...>& t)
 {
   return get_impl<I, tuple<Values...> >::get(t);
 }

 // 6.1.3.5 Relational operators
 inline bool operator==(const tuple<>&, const tuple<>&) { return true; }

 template<typename T, typename... TTail, typename U, typename... UTail>
 bool operator==(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u)
 {
   return t.head() == u.head() && t.tail() == u.tail();
 }

 template<typename... TValues, typename... UValues>
 bool operator!=(const tuple<TValues...>& t, const tuple<UValues...>& u)
 {
   return !(t == u);
 }

 inline bool operator<(const tuple<>&, const tuple<>&) { return false; }

 template<typename T, typename... TTail, typename U, typename... UTail>
 bool operator<(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u)
 {
   return (t.head() < u.head() ||
           (!(t.head() < u.head()) && t.tail() < u.tail()));
 }

 template<typename... TValues, typename... UValues>
 bool operator>(const tuple<TValues...>& t, const tuple<UValues...>& u)
 {
   return u < t;
 }

 template<typename... TValues, typename... UValues>
 bool operator<=(const tuple<TValues...>& t, const tuple<UValues...>& u)
 {
   return !(u < t);
 }

 template<typename... TValues, typename... UValues>
 bool operator>=(const tuple<TValues...>& t, const tuple<UValues...>& u)
 {
   return !(t < u);
 }

 // enable_if, the breakfast of champions
 template<bool Cond, typename Type = void>
 struct enable_if {
   typedef Type type;
 };

 template<typename Type>
 struct enable_if<false, Type> { };

 // 3.6 Function object binders

 // 3.6.1 Class template is_bind_expression
 template<typename T>
 struct is_bind_expression {
   static const bool value = false;
 };

 // 3.6.2 Class template is_placeholder
 template<typename T>
 struct is_placeholder {
   static const int value = 0;
 };

 // 3.6.3 Function template bind
 template<int I> struct placeholder {} ;

 template<int N> struct int_c { };

 // A tuple of integer values
 template<int...> struct int_tuple {};

 // make_indexes_impl is a helper for make_indexes
 template<int I, typename IntTuple, typename... Types>
 struct make_indexes_impl;


 template<int I, int... Indexes, typename T, typename... Types>
 struct make_indexes_impl<I, int_tuple<Indexes...>, T, Types...>
 {
   typedef typename make_indexes_impl<I+1,
                                      int_tuple<Indexes..., I>,
                                      Types...>::type type;
 };

 template<int I, int... Indexes>
 struct make_indexes_impl<I, int_tuple<Indexes...> > {
   typedef int_tuple<Indexes...> type;
 };

 // make_indexes takes a variable-length number of N types and
 // generates an int_tuple that contains <0, 1, 2, ..., N-1>. These can
 // be used as indexes for tuple's get or tuple_element operation.
 template<typename... Types>
 struct make_indexes : make_indexes_impl<0, int_tuple<>, Types...> { };

 // Get the Ith tuple element, but only if I is in bounds.
 template<int I, typename Tuple, typename = void>
 struct safe_tuple_element{ };

 template<int I, typename... Values>
 struct safe_tuple_element<I, tuple<Values...>,
          typename enable_if<(I >= 0 &&
                              I < tuple_size<tuple<Values...> >::value)
                             >::type>
 {
   typedef typename tuple_element<I, tuple<Values...> >::type type;
 };

 // mu maps a bound argument to an actual argument, given a tuple of
 // the arguments passed to the function object returned by bind().

 // Return the stored reference from reference_wrapper
 template<typename T, typename... Args>
 inline T& mu(reference_wrapper<T>& bound_arg, const tuple<Args&...>&)
 {
   return bound_arg.get();
 }

 // Unwrap a tuple into separate arguments and forward to the function
 // object f.
 template<typename F, int... Indexes, typename... Args>
 inline typename F::result_type
 unwrap_and_forward(F& f, int_tuple<Indexes...>, const tuple<Args&...>& args)
 {
   return f(get<Indexes>(args)...);
 }

 // Evaluate the inner bind expression
 template<typename Bound, typename... Args>
 inline typename enable_if<is_bind_expression<Bound>::value,
                           typename Bound::result_type>::type
 mu(Bound& bound_arg, const tuple<Args&...>& args)
 {
   typedef typename make_indexes<Args...>::type Indexes;
   return unwrap_and_forward(bound_arg, Indexes(), args);
 }

 // Retrieve the Ith argument from args
 template<typename Bound, typename... Args>
 inline typename safe_tuple_element<is_placeholder<Bound>::value - 1,
                                    tuple<Args...> >::type
 mu(Bound& bound_arg, const tuple<Args&...>& args)
 {
   return get<is_placeholder<Bound>::value-1>(args);
 }

 // Return the stored value.
 template<typename T>
 struct is_reference_wrapper {
   static const bool value = false;
 };

 template<typename T>
 struct is_reference_wrapper<reference_wrapper<T> > {
   static const bool value = true;
 };

 template<typename Bound, typename... Args>
 inline typename enable_if<(!is_bind_expression<Bound>::value
                            && !is_placeholder<Bound>::value
                            && !is_reference_wrapper<Bound>::value),
                           Bound&>::type
 mu(Bound& bound_arg, const tuple<Args&...>&)
 {
   return bound_arg;
 }

 //
 template<typename F, typename... BoundArgs, int... Indexes, typename... Args>
 typename F::result_type
 apply_functor(F& f, tuple<BoundArgs...>& bound_args, int_tuple<Indexes...>,
               const tuple<Args&...>& args)
 {
   return f(mu(get<Indexes>(bound_args), args)...);
 }

 template<typename F, typename... BoundArgs>
 class bound_functor
 {
   typedef typename make_indexes<BoundArgs...>::type indexes;

  public:
   typedef typename F::result_type result_type;

   explicit bound_functor(const F& f, const BoundArgs&... bound_args)
     : f(f), bound_args(bound_args...) { }

   template<typename... Args>
   typename F::result_type operator()(Args&... args) {
     return apply_functor(f, bound_args, indexes(), tie(args...));
   }

  private:
   F f;
   tuple<BoundArgs...> bound_args;
 };

 template<typename F, typename... BoundArgs>
 struct is_bind_expression<bound_functor<F, BoundArgs...> > {
   static const bool value = true;
 };

 template<typename F, typename... BoundArgs>
 inline bound_functor<F, BoundArgs...>
 bind(const F& f, const BoundArgs&... bound_args)
 {
   return bound_functor<F, BoundArgs...>(f, bound_args...);
 }


 // 3.6.4 Placeholders
 template<int I>
 struct is_placeholder<placeholder<I> > {
   static const int value = I;
 };

 placeholder<1> _1;
 placeholder<2> _2;
 placeholder<3> _3;
 placeholder<4> _4;
 placeholder<5> _5;
 placeholder<6> _6;
 placeholder<7> _7;
 placeholder<8> _8;
 placeholder<9> _9;

 // Test code
 template<typename T>
 struct plus {
   typedef T result_type;

   T operator()(T x, T y) { return x + y; }
 };

 template<typename T>
 struct multiplies {
   typedef T result_type;

   T operator()(T x, T y) { return x * y; }
 };

 template<typename T>
 struct negate {
   typedef T result_type;

   T operator()(T x) { return -x; }
 };

 int main()
 {
   int seventeen = 17;
   int forty_two = 42;

   assert(bind(plus<int>(), _1, _2)(seventeen, forty_two) == 59);
   assert(bind(plus<int>(), _1, _1)(seventeen, forty_two) == 34);
   assert(bind(plus<int>(), _2, _1)(seventeen, forty_two) == 59);
   assert(bind(plus<int>(), 5, _1)(seventeen, forty_two) == 22);
   assert(bind(plus<int>(), ref(seventeen), _2)(seventeen, forty_two) == 59);
   assert(bind(plus<int>(), bind(multiplies<int>(), 3, _1), _2)(seventeen, forty_two)
          == 93);
   return 0;
 }
	// { dg-do run { target c++11 } }
	// A basic implementation of TR1's bind using variadic teplates
	// Contributed by Douglas Gregor <doug.gregor@gmail.com>
	#include <cassert>

	// Trivial reference_wrapper
	template<typename T>
	struct reference_wrapper
	{
	reference_wrapper(T& x) : ptr(&x) { }

	operator T&() const { return *ptr; }

	T& get() const { return *ptr; }

	T* ptr;
	};

	template<typename T> reference_wrapper<T> ref(T& x) { return x; }
	template<typename T> reference_wrapper<const T> cref(const T& x) { return x; }

	// Simple type-traits we'll need
	template<typename T>
	struct add_reference
	{
	typedef T& type;
	};

	template<typename T>
	struct add_reference<T&>
	{
	typedef T& type;
	};

	template<typename T, typename U>
	struct is_same
	{
	static const bool value = false;
	};

	template<typename T>
	struct is_same<T, T>
	{
	static const bool value = true;
	};

	// For creating the constructor parameters of tuple<>
	template<typename T>
	struct add_const_reference
	{
	typedef const T& type;
	};

	template<typename T>
	struct add_const_reference<T&>
	{
	typedef T& type;
	};

	// 6.1.3 Class template tuple: Needed for bind() implementation
	template<typename... Values>
	class tuple;

	template<> class tuple<> { };

	template<typename Head, typename... Tail>
	class tuple<Head, Tail...>
	: private tuple<Tail...>
	{
	typedef tuple<Tail...> inherited;

	public:
	tuple() { }

	// implicit copy-constructor is okay

	tuple(typename add_const_reference<Head>::type v,
	typename add_const_reference<Tail>::type... vtail)
	: m_head(v), inherited(vtail...) { }

	template<typename... VValues>
	tuple(const tuple<VValues...>& other)
	: m_head(other.head()), inherited(other.tail()) { }

	template<typename... VValues>
	tuple& operator=(const tuple<VValues...>& other)
	{
	m_head = other.head();
	tail() = other.tail();
	return *this;
	}

	typename add_reference<Head>::type head() { return m_head; }
	typename add_reference<const Head>::type head() const { return m_head; }
	inherited& tail() { return *this; }
	const inherited& tail() const { return *this; }

	protected:
	Head m_head;
	};

	template<typename T>
	struct make_tuple_result
	{
	typedef T type;
	};

	template<typename T>
	struct make_tuple_result<reference_wrapper<T> >
	{
	typedef T& type;
	};

	// 6.1.3.2 Tuple creation functions
	struct ignore_t {
	template<typename T> ignore_t& operator=(const T&) { return *this; }
	} ignore;

	template<typename... Values>
	tuple<typename make_tuple_result<Values>::type...>
	make_tuple(const Values&... values)
	{
	return tuple<typename make_tuple_result<Values>::type...>(values...);
	}

	template<typename... Values>
	tuple<Values&...> tie(Values&... values)
	{
	return tuple<Values&...>(values...);
	}

	// 6.1.3.3 Tuple helper classes
	template<typename Tuple>
	struct tuple_size;

	template<>
	struct tuple_size<tuple<> >
	{
	static const __SIZE_TYPE__ value = 0;
	};

	template<typename Head, typename... Tail>
	struct tuple_size<tuple<Head, Tail...> >
	{
	static const __SIZE_TYPE__ value = 1 + tuple_size<tuple<Tail...> >::value;
	};

	template<int I, typename Tuple>
	struct tuple_element;

	template<int I, typename Head, typename... Tail>
	struct tuple_element<I, tuple<Head, Tail...> >
	{
	typedef typename tuple_element<I-1, tuple<Tail...> >::type type;
	};

	template<typename Head, typename... Tail>
	struct tuple_element<0, tuple<Head, Tail...> >
	{
	typedef Head type;
	};

	// 6.1.3.4 Element access
	template<int I, typename Tuple>
	class get_impl;

	template<int I, typename Head, typename... Values>
	class get_impl<I, tuple<Head, Values...> >
	{
	typedef typename tuple_element<I-1, tuple<Values...> >::type Element;
	typedef typename add_reference<Element>::type RJ;
	typedef typename add_const_reference<Element>::type PJ;
	typedef get_impl<I-1, tuple<Values...> > Next;

	public:
	static RJ get(tuple<Head, Values...>& t)
	{ return Next::get(t.tail()); }

	static PJ get(const tuple<Head, Values...>& t)
	{ return Next::get(t.tail()); }
	};

	template<typename Head, typename... Values>
	class get_impl<0, tuple<Head, Values...> >
	{
	typedef typename add_reference<Head>::type RJ;
	typedef typename add_const_reference<Head>::type PJ;

	public:
	static RJ get(tuple<Head, Values...>& t) { return t.head(); }
	static PJ get(const tuple<Head, Values...>& t) { return t.head(); }
	};

	template<int I, typename... Values>
	typename add_reference<
	typename tuple_element<I, tuple<Values...> >::type
	>::type
	get(tuple<Values...>& t)
	{
	return get_impl<I, tuple<Values...> >::get(t);
	}

	template<int I, typename... Values>
	typename add_const_reference<
	typename tuple_element<I, tuple<Values...> >::type
	>::type
	get(const tuple<Values...>& t)
	{
	return get_impl<I, tuple<Values...> >::get(t);
	}

	// 6.1.3.5 Relational operators
	inline bool operator==(const tuple<>&, const tuple<>&) { return true; }

	template<typename T, typename... TTail, typename U, typename... UTail>
	bool operator==(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u)
	{
	return t.head() == u.head() && t.tail() == u.tail();
	}

	template<typename... TValues, typename... UValues>
	bool operator!=(const tuple<TValues...>& t, const tuple<UValues...>& u)
	{
	return !(t == u);
	}

	inline bool operator<(const tuple<>&, const tuple<>&) { return false; }

	template<typename T, typename... TTail, typename U, typename... UTail>
	bool operator<(const tuple<T, TTail...>& t, const tuple<U, UTail...>& u)
	{
	return (t.head() < u.head() \|\|
	(!(t.head() < u.head()) && t.tail() < u.tail()));
	}

	template<typename... TValues, typename... UValues>
	bool operator>(const tuple<TValues...>& t, const tuple<UValues...>& u)
	{
	return u < t;
	}

	template<typename... TValues, typename... UValues>
	bool operator<=(const tuple<TValues...>& t, const tuple<UValues...>& u)
	{
	return !(u < t);
	}

	template<typename... TValues, typename... UValues>
	bool operator>=(const tuple<TValues...>& t, const tuple<UValues...>& u)
	{
	return !(t < u);
	}

	// enable_if, the breakfast of champions
	template<bool Cond, typename Type = void>
	struct enable_if {
	typedef Type type;
	};

	template<typename Type>
	struct enable_if<false, Type> { };

	// 3.6 Function object binders

	// 3.6.1 Class template is_bind_expression
	template<typename T>
	struct is_bind_expression {
	static const bool value = false;
	};

	// 3.6.2 Class template is_placeholder
	template<typename T>
	struct is_placeholder {
	static const int value = 0;
	};

	// 3.6.3 Function template bind
	template<int I> struct placeholder {} ;

	template<int N> struct int_c { };

	// A tuple of integer values
	template<int...> struct int_tuple {};

	// make_indexes_impl is a helper for make_indexes
	template<int I, typename IntTuple, typename... Types>
	struct make_indexes_impl;


	template<int I, int... Indexes, typename T, typename... Types>
	struct make_indexes_impl<I, int_tuple<Indexes...>, T, Types...>
	{
	typedef typename make_indexes_impl<I+1,
	int_tuple<Indexes..., I>,
	Types...>::type type;
	};

	template<int I, int... Indexes>
	struct make_indexes_impl<I, int_tuple<Indexes...> > {
	typedef int_tuple<Indexes...> type;
	};

	// make_indexes takes a variable-length number of N types and
	// generates an int_tuple that contains <0, 1, 2, ..., N-1>. These can
	// be used as indexes for tuple's get or tuple_element operation.
	template<typename... Types>
	struct make_indexes : make_indexes_impl<0, int_tuple<>, Types...> { };

	// Get the Ith tuple element, but only if I is in bounds.
	template<int I, typename Tuple, typename = void>
	struct safe_tuple_element{ };

	template<int I, typename... Values>
	struct safe_tuple_element<I, tuple<Values...>,
	typename enable_if<(I >= 0 &&
	I < tuple_size<tuple<Values...> >::value)
	>::type>
	{
	typedef typename tuple_element<I, tuple<Values...> >::type type;
	};

	// mu maps a bound argument to an actual argument, given a tuple of
	// the arguments passed to the function object returned by bind().

	// Return the stored reference from reference_wrapper
	template<typename T, typename... Args>
	inline T& mu(reference_wrapper<T>& bound_arg, const tuple<Args&...>&)
	{
	return bound_arg.get();
	}

	// Unwrap a tuple into separate arguments and forward to the function
	// object f.
	template<typename F, int... Indexes, typename... Args>
	inline typename F::result_type
	unwrap_and_forward(F& f, int_tuple<Indexes...>, const tuple<Args&...>& args)
	{
	return f(get<Indexes>(args)...);
	}

	// Evaluate the inner bind expression
	template<typename Bound, typename... Args>
	inline typename enable_if<is_bind_expression<Bound>::value,
	typename Bound::result_type>::type
	mu(Bound& bound_arg, const tuple<Args&...>& args)
	{
	typedef typename make_indexes<Args...>::type Indexes;
	return unwrap_and_forward(bound_arg, Indexes(), args);
	}

	// Retrieve the Ith argument from args
	template<typename Bound, typename... Args>
	inline typename safe_tuple_element<is_placeholder<Bound>::value - 1,
	tuple<Args...> >::type
	mu(Bound& bound_arg, const tuple<Args&...>& args)
	{
	return get<is_placeholder<Bound>::value-1>(args);
	}

	// Return the stored value.
	template<typename T>
	struct is_reference_wrapper {
	static const bool value = false;
	};

	template<typename T>
	struct is_reference_wrapper<reference_wrapper<T> > {
	static const bool value = true;
	};

	template<typename Bound, typename... Args>
	inline typename enable_if<(!is_bind_expression<Bound>::value
	&& !is_placeholder<Bound>::value
	&& !is_reference_wrapper<Bound>::value),
	Bound&>::type
	mu(Bound& bound_arg, const tuple<Args&...>&)
	{
	return bound_arg;
	}

	//
	template<typename F, typename... BoundArgs, int... Indexes, typename... Args>
	typename F::result_type
	apply_functor(F& f, tuple<BoundArgs...>& bound_args, int_tuple<Indexes...>,
	const tuple<Args&...>& args)
	{
	return f(mu(get<Indexes>(bound_args), args)...);
	}

	template<typename F, typename... BoundArgs>
	class bound_functor
	{
	typedef typename make_indexes<BoundArgs...>::type indexes;

	public:
	typedef typename F::result_type result_type;

	explicit bound_functor(const F& f, const BoundArgs&... bound_args)
	: f(f), bound_args(bound_args...) { }

	template<typename... Args>
	typename F::result_type operator()(Args&... args) {
	return apply_functor(f, bound_args, indexes(), tie(args...));
	}

	private:
	F f;
	tuple<BoundArgs...> bound_args;
	};

	template<typename F, typename... BoundArgs>
	struct is_bind_expression<bound_functor<F, BoundArgs...> > {
	static const bool value = true;
	};

	template<typename F, typename... BoundArgs>
	inline bound_functor<F, BoundArgs...>
	bind(const F& f, const BoundArgs&... bound_args)
	{
	return bound_functor<F, BoundArgs...>(f, bound_args...);
	}


	// 3.6.4 Placeholders
	template<int I>
	struct is_placeholder<placeholder<I> > {
	static const int value = I;
	};

	placeholder<1> _1;
	placeholder<2> _2;
	placeholder<3> _3;
	placeholder<4> _4;
	placeholder<5> _5;
	placeholder<6> _6;
	placeholder<7> _7;
	placeholder<8> _8;
	placeholder<9> _9;

	// Test code
	template<typename T>
	struct plus {
	typedef T result_type;

	T operator()(T x, T y) { return x + y; }
	};

	template<typename T>
	struct multiplies {
	typedef T result_type;

	T operator()(T x, T y) { return x * y; }
	};

	template<typename T>
	struct negate {
	typedef T result_type;

	T operator()(T x) { return -x; }
	};

	int main()
	{
	int seventeen = 17;
	int forty_two = 42;

	assert(bind(plus<int>(), _1, _2)(seventeen, forty_two) == 59);
	assert(bind(plus<int>(), _1, _1)(seventeen, forty_two) == 34);
	assert(bind(plus<int>(), _2, _1)(seventeen, forty_two) == 59);
	assert(bind(plus<int>(), 5, _1)(seventeen, forty_two) == 22);
	assert(bind(plus<int>(), ref(seventeen), _2)(seventeen, forty_two) == 59);
	assert(bind(plus<int>(), bind(multiplies<int>(), 3, _1), _2)(seventeen, forty_two)
	== 93);
	return 0;
	}