// Functor implementations -*- C++ -*-
-// Copyright (C) 2001-2019 Free Software Foundation, Inc.
+// Copyright (C) 2001-2024 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// 20.3.1 base classes
/** @defgroup functors Function Objects
- * @ingroup utilities
+ * @ingroup utilities
*
- * Function objects, or @e functors, are objects with an @c operator()
+ * Function objects, or _functors_, are objects with an `operator()`
* defined and accessible. They can be passed as arguments to algorithm
* templates and used in place of a function pointer. Not only is the
* resulting expressiveness of the library increased, but the generated
* code can be more efficient than what you might write by hand. When we
- * refer to @a functors, then, generally we include function pointers in
+ * refer to _functors_, then, generally we include function pointers in
* the description as well.
*
* Often, functors are only created as temporaries passed to algorithm
* calls, rather than being created as named variables.
*
* Two examples taken from the standard itself follow. To perform a
- * by-element addition of two vectors @c a and @c b containing @c double,
- * and put the result in @c a, use
+ * by-element addition of two vectors `a` and `b` containing `double`,
+ * and put the result in `a`, use
* \code
* transform (a.begin(), a.end(), b.begin(), a.begin(), plus<double>());
* \endcode
- * To negate every element in @c a, use
+ * To negate every element in `a`, use
* \code
* transform(a.begin(), a.end(), a.begin(), negate<double>());
* \endcode
- * The addition and negation functions will be inlined directly.
+ * The addition and negation functions will usually be inlined directly.
*
- * The standard functors are derived from structs named @c unary_function
- * and @c binary_function. These two classes contain nothing but typedefs,
- * to aid in generic (template) programming. If you write your own
- * functors, you might consider doing the same.
+ * An _adaptable function object_ is one which provides nested typedefs
+ * `result_type` and either `argument_type` (for a unary function) or
+ * `first_argument_type` and `second_argument_type` (for a binary function).
+ * Those typedefs are used by function object adaptors such as `bind2nd`.
+ * The standard library provides two class templates, `unary_function` and
+ * `binary_function`, which define those typedefs and so can be used as
+ * base classes of adaptable function objects.
+ *
+ * Since C++11 the use of function object adaptors has been superseded by
+ * more powerful tools such as lambda expressions, `function<>`, and more
+ * powerful type deduction (using `auto` and `decltype`). The helpers for
+ * defining adaptable function objects are deprecated since C++11, and no
+ * longer part of the standard library since C++17. However, they are still
+ * defined and used by libstdc++ after C++17, as a conforming extension.
*
* @{
*/
+
/**
- * This is one of the @link functors functor base classes@endlink.
+ * Helper for defining adaptable unary function objects.
+ * @deprecated Deprecated in C++11, no longer in the standard since C++17.
*/
template<typename _Arg, typename _Result>
struct unary_function
/// @c result_type is the return type
typedef _Result result_type;
- };
+ } _GLIBCXX11_DEPRECATED;
/**
- * This is one of the @link functors functor base classes@endlink.
+ * Helper for defining adaptable binary function objects.
+ * @deprecated Deprecated in C++11, no longer in the standard since C++17.
*/
template<typename _Arg1, typename _Arg2, typename _Result>
struct binary_function
/// @c result_type is the return type
typedef _Result result_type;
- };
+ } _GLIBCXX11_DEPRECATED;
/** @} */
// 20.3.2 arithmetic
- /** @defgroup arithmetic_functors Arithmetic Classes
- * @ingroup functors
+
+ /** @defgroup arithmetic_functors Arithmetic Function Object Classes
+ * @ingroup functors
*
- * Because basic math often needs to be done during an algorithm,
- * the library provides functors for those operations. See the
- * documentation for @link functors the base classes@endlink
+ * The library provides function objects for basic arithmetic operations.
+ * See the documentation for @link functors function objects @endlink
* for examples of their use.
*
* @{
*/
-#if __cplusplus > 201103L
+#if __glibcxx_transparent_operators // C++ >= 14
struct __is_transparent; // undefined
template<typename _Tp = void>
struct negate;
#endif
+// Ignore warnings about unary_function and binary_function.
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+
/// One of the @link arithmetic_functors math functors@endlink.
template<typename _Tp>
struct plus : public binary_function<_Tp, _Tp, _Tp>
{
+ /// Returns the sum
_GLIBCXX14_CONSTEXPR
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
operator()(const _Tp& __x) const
{ return -__x; }
};
+#pragma GCC diagnostic pop
-#if __cplusplus > 201103L
-
-#define __cpp_lib_transparent_operators 201510
-
+#ifdef __glibcxx_transparent_operators // C++ >= 14
template<>
struct plus<void>
{
// 20.3.3 comparisons
/** @defgroup comparison_functors Comparison Classes
- * @ingroup functors
+ * @ingroup functors
*
* The library provides six wrapper functors for all the basic comparisons
* in C++, like @c <.
*
* @{
*/
-#if __cplusplus > 201103L
+#if __glibcxx_transparent_operators // C++ >= 14
template<typename _Tp = void>
struct equal_to;
struct less_equal;
#endif
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+
/// One of the @link comparison_functors comparison functors@endlink.
template<typename _Tp>
struct equal_to : public binary_function<_Tp, _Tp, bool>
operator()(_Tp* __x, _Tp* __y) const _GLIBCXX_NOTHROW
{
#if __cplusplus >= 201402L
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
-#else
- if (__builtin_constant_p(__x > __y))
-#endif
+ if (std::__is_constant_evaluated())
return __x > __y;
#endif
return (__UINTPTR_TYPE__)__x > (__UINTPTR_TYPE__)__y;
operator()(_Tp* __x, _Tp* __y) const _GLIBCXX_NOTHROW
{
#if __cplusplus >= 201402L
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
-#else
- if (__builtin_constant_p(__x < __y))
-#endif
+ if (std::__is_constant_evaluated())
return __x < __y;
#endif
return (__UINTPTR_TYPE__)__x < (__UINTPTR_TYPE__)__y;
operator()(_Tp* __x, _Tp* __y) const _GLIBCXX_NOTHROW
{
#if __cplusplus >= 201402L
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
-#else
- if (__builtin_constant_p(__x >= __y))
-#endif
+ if (std::__is_constant_evaluated())
return __x >= __y;
#endif
return (__UINTPTR_TYPE__)__x >= (__UINTPTR_TYPE__)__y;
operator()(_Tp* __x, _Tp* __y) const _GLIBCXX_NOTHROW
{
#if __cplusplus >= 201402L
-#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
- if (__builtin_is_constant_evaluated())
-#else
- if (__builtin_constant_p(__x <= __y))
-#endif
+ if (std::__is_constant_evaluated())
return __x <= __y;
#endif
return (__UINTPTR_TYPE__)__x <= (__UINTPTR_TYPE__)__y;
}
};
+#pragma GCC diagnostic pop
-#if __cplusplus >= 201402L
+#ifdef __glibcxx_transparent_operators // C++ >= 14
/// One of the @link comparison_functors comparison functors@endlink.
template<>
struct equal_to<void>
is_convertible<_Tp, const volatile void*>,
is_convertible<_Up, const volatile void*>>;
};
-#endif // C++14
+#endif // __glibcxx_transparent_operators
/** @} */
// 20.3.4 logical operations
/** @defgroup logical_functors Boolean Operations Classes
- * @ingroup functors
+ * @ingroup functors
*
- * Here are wrapper functors for Boolean operations: @c &&, @c ||,
- * and @c !.
+ * The library provides function objects for the logical operations:
+ * `&&`, `||`, and `!`.
*
* @{
*/
-#if __cplusplus > 201103L
+#ifdef __glibcxx_transparent_operators // C++ >= 14
template<typename _Tp = void>
struct logical_and;
struct logical_not;
#endif
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+
/// One of the @link logical_functors Boolean operations functors@endlink.
template<typename _Tp>
struct logical_and : public binary_function<_Tp, _Tp, bool>
operator()(const _Tp& __x) const
{ return !__x; }
};
+#pragma GCC diagnostic pop
-#if __cplusplus > 201103L
+#ifdef __glibcxx_transparent_operators // C++ >= 14
/// One of the @link logical_functors Boolean operations functors@endlink.
template<>
struct logical_and<void>
typedef __is_transparent is_transparent;
};
-#endif
+#endif // __glibcxx_transparent_operators
/** @} */
-#if __cplusplus > 201103L
+#ifdef __glibcxx_transparent_operators // C++ >= 14
template<typename _Tp = void>
struct bit_and;
struct bit_not;
#endif
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
+
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 660. Missing Bitwise Operations.
template<typename _Tp>
operator()(const _Tp& __x) const
{ return ~__x; }
};
+#pragma GCC diagnostic pop
-#if __cplusplus > 201103L
+#ifdef __glibcxx_transparent_operators // C++ >= 14
template <>
struct bit_and<void>
{
typedef __is_transparent is_transparent;
};
-#endif
+#endif // C++14
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wdeprecated-declarations"
// 20.3.5 negators
/** @defgroup negators Negators
- * @ingroup functors
+ * @ingroup functors
*
- * The functions @c not1 and @c not2 each take a predicate functor
- * and return an instance of @c unary_negate or
- * @c binary_negate, respectively. These classes are functors whose
- * @c operator() performs the stored predicate function and then returns
- * the negation of the result.
+ * The function templates `not1` and `not2` are function object adaptors,
+ * which each take a predicate functor and wrap it in an instance of
+ * `unary_negate` or `binary_negate`, respectively. Those classes are
+ * functors whose `operator()` evaluates the wrapped predicate function
+ * and then returns the negation of the result.
*
* For example, given a vector of integers and a trivial predicate,
* \code
* struct IntGreaterThanThree
* : public std::unary_function<int, bool>
* {
- * bool operator() (int x) { return x > 3; }
+ * bool operator() (int x) const { return x > 3; }
* };
*
* std::find_if (v.begin(), v.end(), not1(IntGreaterThanThree()));
* \endcode
- * The call to @c find_if will locate the first index (i) of @c v for which
- * <code>!(v[i] > 3)</code> is true.
+ * The call to `find_if` will locate the first index (i) of `v` for which
+ * `!(v[i] > 3)` is true.
*
* The not1/unary_negate combination works on predicates taking a single
- * argument. The not2/binary_negate combination works on predicates which
- * take two arguments.
+ * argument. The not2/binary_negate combination works on predicates taking
+ * two arguments.
+ *
+ * @deprecated Deprecated in C++17, no longer in the standard since C++20.
+ * Use `not_fn` instead.
*
* @{
*/
/// One of the @link negators negation functors@endlink.
template<typename _Predicate>
- class unary_negate
+ class _GLIBCXX17_DEPRECATED unary_negate
: public unary_function<typename _Predicate::argument_type, bool>
{
protected:
/// One of the @link negators negation functors@endlink.
template<typename _Predicate>
+ _GLIBCXX17_DEPRECATED_SUGGEST("std::not_fn")
_GLIBCXX14_CONSTEXPR
inline unary_negate<_Predicate>
not1(const _Predicate& __pred)
/// One of the @link negators negation functors@endlink.
template<typename _Predicate>
- class binary_negate
+ class _GLIBCXX17_DEPRECATED binary_negate
: public binary_function<typename _Predicate::first_argument_type,
typename _Predicate::second_argument_type, bool>
{
/// One of the @link negators negation functors@endlink.
template<typename _Predicate>
+ _GLIBCXX17_DEPRECATED_SUGGEST("std::not_fn")
_GLIBCXX14_CONSTEXPR
inline binary_negate<_Predicate>
not2(const _Predicate& __pred)
// 20.3.7 adaptors pointers functions
/** @defgroup pointer_adaptors Adaptors for pointers to functions
- * @ingroup functors
+ * @ingroup functors
*
* The advantage of function objects over pointers to functions is that
* the objects in the standard library declare nested typedefs describing
- * their argument and result types with uniform names (e.g., @c result_type
- * from the base classes @c unary_function and @c binary_function).
+ * their argument and result types with uniform names (e.g., `result_type`
+ * from the base classes `unary_function` and `binary_function`).
* Sometimes those typedefs are required, not just optional.
*
* Adaptors are provided to turn pointers to unary (single-argument) and
* binary (double-argument) functions into function objects. The
- * long-winded functor @c pointer_to_unary_function is constructed with a
- * function pointer @c f, and its @c operator() called with argument @c x
- * returns @c f(x). The functor @c pointer_to_binary_function does the same
- * thing, but with a double-argument @c f and @c operator().
+ * long-winded functor `pointer_to_unary_function` is constructed with a
+ * function pointer `f`, and its `operator()` called with argument `x`
+ * returns `f(x)`. The functor `pointer_to_binary_function` does the same
+ * thing, but with a double-argument `f` and `operator()`.
*
- * The function @c ptr_fun takes a pointer-to-function @c f and constructs
+ * The function `ptr_fun` takes a pointer-to-function `f` and constructs
* an instance of the appropriate functor.
*
+ * @deprecated Deprecated in C++11, no longer in the standard since C++17.
+ *
* @{
*/
/// One of the @link pointer_adaptors adaptors for function pointers@endlink.
_Result
operator()(_Arg __x) const
{ return _M_ptr(__x); }
- };
+ } _GLIBCXX11_DEPRECATED;
/// One of the @link pointer_adaptors adaptors for function pointers@endlink.
template<typename _Arg, typename _Result>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::function")
inline pointer_to_unary_function<_Arg, _Result>
ptr_fun(_Result (*__x)(_Arg))
{ return pointer_to_unary_function<_Arg, _Result>(__x); }
_Result
operator()(_Arg1 __x, _Arg2 __y) const
{ return _M_ptr(__x, __y); }
- };
+ } _GLIBCXX11_DEPRECATED;
/// One of the @link pointer_adaptors adaptors for function pointers@endlink.
template<typename _Arg1, typename _Arg2, typename _Result>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::function")
inline pointer_to_binary_function<_Arg1, _Arg2, _Result>
ptr_fun(_Result (*__x)(_Arg1, _Arg2))
{ return pointer_to_binary_function<_Arg1, _Arg2, _Result>(__x); }
};
// 20.3.8 adaptors pointers members
- /** @defgroup memory_adaptors Adaptors for pointers to members
- * @ingroup functors
+ /** @defgroup ptrmem_adaptors Adaptors for pointers to members
+ * @ingroup functors
*
* There are a total of 8 = 2^3 function objects in this family.
* (1) Member functions taking no arguments vs member functions taking
* (3) Const vs non-const member function.
*
* All of this complexity is in the function objects themselves. You can
- * ignore it by using the helper function mem_fun and mem_fun_ref,
+ * ignore it by using the helper function `mem_fun` and `mem_fun_ref`,
* which create whichever type of adaptor is appropriate.
*
+ * @deprecated Deprecated in C++11, no longer in the standard since C++17.
+ * Use `mem_fn` instead.
+ *
* @{
*/
- /// One of the @link memory_adaptors adaptors for member
- /// pointers@endlink.
+ /// One of the @link ptrmem_adaptors adaptors for member pointers@endlink.
template<typename _Ret, typename _Tp>
class mem_fun_t : public unary_function<_Tp*, _Ret>
{
private:
_Ret (_Tp::*_M_f)();
- };
+ } _GLIBCXX11_DEPRECATED;
- /// One of the @link memory_adaptors adaptors for member
- /// pointers@endlink.
+ /// One of the @link ptrmem_adaptors adaptors for member pointers@endlink.
template<typename _Ret, typename _Tp>
class const_mem_fun_t : public unary_function<const _Tp*, _Ret>
{
private:
_Ret (_Tp::*_M_f)() const;
- };
+ } _GLIBCXX11_DEPRECATED;
- /// One of the @link memory_adaptors adaptors for member
- /// pointers@endlink.
+ /// One of the @link ptrmem_adaptors adaptors for member pointers@endlink.
template<typename _Ret, typename _Tp>
class mem_fun_ref_t : public unary_function<_Tp, _Ret>
{
private:
_Ret (_Tp::*_M_f)();
- };
+ } _GLIBCXX11_DEPRECATED;
- /// One of the @link memory_adaptors adaptors for member
- /// pointers@endlink.
+ /// One of the @link ptrmem_adaptors adaptors for member pointers@endlink.
template<typename _Ret, typename _Tp>
class const_mem_fun_ref_t : public unary_function<_Tp, _Ret>
{
private:
_Ret (_Tp::*_M_f)() const;
- };
+ } _GLIBCXX11_DEPRECATED;
- /// One of the @link memory_adaptors adaptors for member
- /// pointers@endlink.
+ /// One of the @link ptrmem_adaptors adaptors for member pointers@endlink.
template<typename _Ret, typename _Tp, typename _Arg>
class mem_fun1_t : public binary_function<_Tp*, _Arg, _Ret>
{
private:
_Ret (_Tp::*_M_f)(_Arg);
- };
+ } _GLIBCXX11_DEPRECATED;
- /// One of the @link memory_adaptors adaptors for member
- /// pointers@endlink.
+ /// One of the @link ptrmem_adaptors adaptors for member pointers@endlink.
template<typename _Ret, typename _Tp, typename _Arg>
class const_mem_fun1_t : public binary_function<const _Tp*, _Arg, _Ret>
{
private:
_Ret (_Tp::*_M_f)(_Arg) const;
- };
+ } _GLIBCXX11_DEPRECATED;
- /// One of the @link memory_adaptors adaptors for member
- /// pointers@endlink.
+ /// One of the @link ptrmem_adaptors adaptors for member pointers@endlink.
template<typename _Ret, typename _Tp, typename _Arg>
class mem_fun1_ref_t : public binary_function<_Tp, _Arg, _Ret>
{
private:
_Ret (_Tp::*_M_f)(_Arg);
- };
+ } _GLIBCXX11_DEPRECATED;
- /// One of the @link memory_adaptors adaptors for member
- /// pointers@endlink.
+ /// One of the @link ptrmem_adaptors adaptors for member pointers@endlink.
template<typename _Ret, typename _Tp, typename _Arg>
class const_mem_fun1_ref_t : public binary_function<_Tp, _Arg, _Ret>
{
private:
_Ret (_Tp::*_M_f)(_Arg) const;
- };
+ } _GLIBCXX11_DEPRECATED;
// Mem_fun adaptor helper functions. There are only two:
// mem_fun and mem_fun_ref.
template<typename _Ret, typename _Tp>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::mem_fn")
inline mem_fun_t<_Ret, _Tp>
mem_fun(_Ret (_Tp::*__f)())
{ return mem_fun_t<_Ret, _Tp>(__f); }
template<typename _Ret, typename _Tp>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::mem_fn")
inline const_mem_fun_t<_Ret, _Tp>
mem_fun(_Ret (_Tp::*__f)() const)
{ return const_mem_fun_t<_Ret, _Tp>(__f); }
template<typename _Ret, typename _Tp>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::mem_fn")
inline mem_fun_ref_t<_Ret, _Tp>
mem_fun_ref(_Ret (_Tp::*__f)())
{ return mem_fun_ref_t<_Ret, _Tp>(__f); }
template<typename _Ret, typename _Tp>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::mem_fn")
inline const_mem_fun_ref_t<_Ret, _Tp>
mem_fun_ref(_Ret (_Tp::*__f)() const)
{ return const_mem_fun_ref_t<_Ret, _Tp>(__f); }
template<typename _Ret, typename _Tp, typename _Arg>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::mem_fn")
inline mem_fun1_t<_Ret, _Tp, _Arg>
mem_fun(_Ret (_Tp::*__f)(_Arg))
{ return mem_fun1_t<_Ret, _Tp, _Arg>(__f); }
template<typename _Ret, typename _Tp, typename _Arg>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::mem_fn")
inline const_mem_fun1_t<_Ret, _Tp, _Arg>
mem_fun(_Ret (_Tp::*__f)(_Arg) const)
{ return const_mem_fun1_t<_Ret, _Tp, _Arg>(__f); }
template<typename _Ret, typename _Tp, typename _Arg>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::mem_fn")
inline mem_fun1_ref_t<_Ret, _Tp, _Arg>
mem_fun_ref(_Ret (_Tp::*__f)(_Arg))
{ return mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); }
template<typename _Ret, typename _Tp, typename _Arg>
+ _GLIBCXX11_DEPRECATED_SUGGEST("std::mem_fn")
inline const_mem_fun1_ref_t<_Ret, _Tp, _Arg>
mem_fun_ref(_Ret (_Tp::*__f)(_Arg) const)
{ return const_mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); }
+#pragma GCC diagnostic pop
/** @} */
+#ifdef __glibcxx_transparent_operators // C++ >= 14
+ template<typename _Func, typename _SfinaeType, typename = __void_t<>>
+ struct __has_is_transparent
+ { };
+
+ template<typename _Func, typename _SfinaeType>
+ struct __has_is_transparent<_Func, _SfinaeType,
+ __void_t<typename _Func::is_transparent>>
+ { typedef void type; };
+
+ template<typename _Func, typename _SfinaeType>
+ using __has_is_transparent_t
+ = typename __has_is_transparent<_Func, _SfinaeType>::type;
+#endif
+
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace