stl_function.h
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// Functor implementations -*- C++ -*-
// Copyright (C) 2001-2013 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
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996-1998
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/** @file bits/stl_function.h
* This is an internal header file, included by other library headers.
* Do not attempt to use it directly. @headername{functional}
*/
#ifndef _STL_FUNCTION_H
#define _STL_FUNCTION_H 1
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
// 20.3.1 base classes
/** @defgroup functors Function Objects
* @ingroup utilities
*
* Function objects, or @e functors, are objects with an @c 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
* 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
* \code
* transform (a.begin(), a.end(), b.begin(), a.begin(), plus<double>());
* \endcode
* To negate every element in @c a, use
* \code
* transform(a.begin(), a.end(), a.begin(), negate<double>());
* \endcode
* The addition and negation functions will 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.
*
* @{
*/
/**
* This is one of the @link functors functor base classes@endlink.
*/
template<typename _Arg, typename _Result>
struct unary_function
{
/// @c argument_type is the type of the argument
typedef _Arg argument_type;
/// @c result_type is the return type
typedef _Result result_type;
};
/**
* This is one of the @link functors functor base classes@endlink.
*/
template<typename _Arg1, typename _Arg2, typename _Result>
struct binary_function
{
/// @c first_argument_type is the type of the first argument
typedef _Arg1 first_argument_type;
/// @c second_argument_type is the type of the second argument
typedef _Arg2 second_argument_type;
/// @c result_type is the return type
typedef _Result result_type;
};
/** @} */
// 20.3.2 arithmetic
/** @defgroup arithmetic_functors Arithmetic 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
* for examples of their use.
*
* @{
*/
/// One of the @link arithmetic_functors math functors@endlink.
template<typename _Tp>
struct plus : public binary_function<_Tp, _Tp, _Tp>
{
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x + __y; }
};
/// One of the @link arithmetic_functors math functors@endlink.
template<typename _Tp>
struct minus : public binary_function<_Tp, _Tp, _Tp>
{
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x - __y; }
};
/// One of the @link arithmetic_functors math functors@endlink.
template<typename _Tp>
struct multiplies : public binary_function<_Tp, _Tp, _Tp>
{
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x * __y; }
};
/// One of the @link arithmetic_functors math functors@endlink.
template<typename _Tp>
struct divides : public binary_function<_Tp, _Tp, _Tp>
{
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x / __y; }
};
/// One of the @link arithmetic_functors math functors@endlink.
template<typename _Tp>
struct modulus : public binary_function<_Tp, _Tp, _Tp>
{
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x % __y; }
};
/// One of the @link arithmetic_functors math functors@endlink.
template<typename _Tp>
struct negate : public unary_function<_Tp, _Tp>
{
_Tp
operator()(const _Tp& __x) const
{ return -__x; }
};
/** @} */
// 20.3.3 comparisons
/** @defgroup comparison_functors Comparison Classes
* @ingroup functors
*
* The library provides six wrapper functors for all the basic comparisons
* in C++, like @c <.
*
* @{
*/
/// One of the @link comparison_functors comparison functors@endlink.
template<typename _Tp>
struct equal_to : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x == __y; }
};
/// One of the @link comparison_functors comparison functors@endlink.
template<typename _Tp>
struct not_equal_to : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x != __y; }
};
/// One of the @link comparison_functors comparison functors@endlink.
template<typename _Tp>
struct greater : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x > __y; }
};
/// One of the @link comparison_functors comparison functors@endlink.
template<typename _Tp>
struct less : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x < __y; }
};
/// One of the @link comparison_functors comparison functors@endlink.
template<typename _Tp>
struct greater_equal : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x >= __y; }
};
/// One of the @link comparison_functors comparison functors@endlink.
template<typename _Tp>
struct less_equal : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x <= __y; }
};
/** @} */
// 20.3.4 logical operations
/** @defgroup logical_functors Boolean Operations Classes
* @ingroup functors
*
* Here are wrapper functors for Boolean operations: @c &&, @c ||,
* and @c !.
*
* @{
*/
/// One of the @link logical_functors Boolean operations functors@endlink.
template<typename _Tp>
struct logical_and : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x && __y; }
};
/// One of the @link logical_functors Boolean operations functors@endlink.
template<typename _Tp>
struct logical_or : public binary_function<_Tp, _Tp, bool>
{
bool
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x || __y; }
};
/// One of the @link logical_functors Boolean operations functors@endlink.
template<typename _Tp>
struct logical_not : public unary_function<_Tp, bool>
{
bool
operator()(const _Tp& __x) const
{ return !__x; }
};
/** @} */
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// DR 660. Missing Bitwise Operations.
template<typename _Tp>
struct bit_and : public binary_function<_Tp, _Tp, _Tp>
{
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x & __y; }
};
template<typename _Tp>
struct bit_or : public binary_function<_Tp, _Tp, _Tp>
{
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x | __y; }
};
template<typename _Tp>
struct bit_xor : public binary_function<_Tp, _Tp, _Tp>
{
_Tp
operator()(const _Tp& __x, const _Tp& __y) const
{ return __x ^ __y; }
};
// 20.3.5 negators
/** @defgroup negators Negators
* @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.
*
* 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; }
* };
*
* 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 not1/unary_negate combination works on predicates taking a single
* argument. The not2/binary_negate combination works on predicates which
* take two arguments.
*
* @{
*/
/// One of the @link negators negation functors@endlink.
template<typename _Predicate>
class unary_negate
: public unary_function<typename _Predicate::argument_type, bool>
{
protected:
_Predicate _M_pred;
public:
explicit
unary_negate(const _Predicate& __x) : _M_pred(__x) { }
bool
operator()(const typename _Predicate::argument_type& __x) const
{ return !_M_pred(__x); }
};
/// One of the @link negators negation functors@endlink.
template<typename _Predicate>
inline unary_negate<_Predicate>
not1(const _Predicate& __pred)
{ return unary_negate<_Predicate>(__pred); }
/// One of the @link negators negation functors@endlink.
template<typename _Predicate>
class binary_negate
: public binary_function<typename _Predicate::first_argument_type,
typename _Predicate::second_argument_type, bool>
{
protected:
_Predicate _M_pred;
public:
explicit
binary_negate(const _Predicate& __x) : _M_pred(__x) { }
bool
operator()(const typename _Predicate::first_argument_type& __x,
const typename _Predicate::second_argument_type& __y) const
{ return !_M_pred(__x, __y); }
};
/// One of the @link negators negation functors@endlink.
template<typename _Predicate>
inline binary_negate<_Predicate>
not2(const _Predicate& __pred)
{ return binary_negate<_Predicate>(__pred); }
/** @} */
// 20.3.7 adaptors pointers functions
/** @defgroup pointer_adaptors Adaptors for pointers to functions
* @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).
* 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().
*
* The function @c ptr_fun takes a pointer-to-function @c f and constructs
* an instance of the appropriate functor.
*
* @{
*/
/// One of the @link pointer_adaptors adaptors for function pointers@endlink.
template<typename _Arg, typename _Result>
class pointer_to_unary_function : public unary_function<_Arg, _Result>
{
protected:
_Result (*_M_ptr)(_Arg);
public:
pointer_to_unary_function() { }
explicit
pointer_to_unary_function(_Result (*__x)(_Arg))
: _M_ptr(__x) { }
_Result
operator()(_Arg __x) const
{ return _M_ptr(__x); }
};
/// One of the @link pointer_adaptors adaptors for function pointers@endlink.
template<typename _Arg, typename _Result>
inline pointer_to_unary_function<_Arg, _Result>
ptr_fun(_Result (*__x)(_Arg))
{ return pointer_to_unary_function<_Arg, _Result>(__x); }
/// One of the @link pointer_adaptors adaptors for function pointers@endlink.
template<typename _Arg1, typename _Arg2, typename _Result>
class pointer_to_binary_function
: public binary_function<_Arg1, _Arg2, _Result>
{
protected:
_Result (*_M_ptr)(_Arg1, _Arg2);
public:
pointer_to_binary_function() { }
explicit
pointer_to_binary_function(_Result (*__x)(_Arg1, _Arg2))
: _M_ptr(__x) { }
_Result
operator()(_Arg1 __x, _Arg2 __y) const
{ return _M_ptr(__x, __y); }
};
/// One of the @link pointer_adaptors adaptors for function pointers@endlink.
template<typename _Arg1, typename _Arg2, typename _Result>
inline pointer_to_binary_function<_Arg1, _Arg2, _Result>
ptr_fun(_Result (*__x)(_Arg1, _Arg2))
{ return pointer_to_binary_function<_Arg1, _Arg2, _Result>(__x); }
/** @} */
template<typename _Tp>
struct _Identity
: public unary_function<_Tp,_Tp>
{
_Tp&
operator()(_Tp& __x) const
{ return __x; }
const _Tp&
operator()(const _Tp& __x) const
{ return __x; }
};
template<typename _Pair>
struct _Select1st
: public unary_function<_Pair, typename _Pair::first_type>
{
typename _Pair::first_type&
operator()(_Pair& __x) const
{ return __x.first; }
const typename _Pair::first_type&
operator()(const _Pair& __x) const
{ return __x.first; }
#if __cplusplus >= 201103L
template<typename _Pair2>
typename _Pair2::first_type&
operator()(_Pair2& __x) const
{ return __x.first; }
template<typename _Pair2>
const typename _Pair2::first_type&
operator()(const _Pair2& __x) const
{ return __x.first; }
#endif
};
template<typename _Pair>
struct _Select2nd
: public unary_function<_Pair, typename _Pair::second_type>
{
typename _Pair::second_type&
operator()(_Pair& __x) const
{ return __x.second; }
const typename _Pair::second_type&
operator()(const _Pair& __x) const
{ return __x.second; }
};
// 20.3.8 adaptors pointers members
/** @defgroup memory_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
* one argument.
* (2) Call through pointer vs call through reference.
* (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,
* which create whichever type of adaptor is appropriate.
*
* @{
*/
/// One of the @link memory_adaptors adaptors for member
/// pointers@endlink.
template<typename _Ret, typename _Tp>
class mem_fun_t : public unary_function<_Tp*, _Ret>
{
public:
explicit
mem_fun_t(_Ret (_Tp::*__pf)())
: _M_f(__pf) { }
_Ret
operator()(_Tp* __p) const
{ return (__p->*_M_f)(); }
private:
_Ret (_Tp::*_M_f)();
};
/// One of the @link memory_adaptors adaptors for member
/// pointers@endlink.
template<typename _Ret, typename _Tp>
class const_mem_fun_t : public unary_function<const _Tp*, _Ret>
{
public:
explicit
const_mem_fun_t(_Ret (_Tp::*__pf)() const)
: _M_f(__pf) { }
_Ret
operator()(const _Tp* __p) const
{ return (__p->*_M_f)(); }
private:
_Ret (_Tp::*_M_f)() const;
};
/// One of the @link memory_adaptors adaptors for member
/// pointers@endlink.
template<typename _Ret, typename _Tp>
class mem_fun_ref_t : public unary_function<_Tp, _Ret>
{
public:
explicit
mem_fun_ref_t(_Ret (_Tp::*__pf)())
: _M_f(__pf) { }
_Ret
operator()(_Tp& __r) const
{ return (__r.*_M_f)(); }
private:
_Ret (_Tp::*_M_f)();
};
/// One of the @link memory_adaptors adaptors for member
/// pointers@endlink.
template<typename _Ret, typename _Tp>
class const_mem_fun_ref_t : public unary_function<_Tp, _Ret>
{
public:
explicit
const_mem_fun_ref_t(_Ret (_Tp::*__pf)() const)
: _M_f(__pf) { }
_Ret
operator()(const _Tp& __r) const
{ return (__r.*_M_f)(); }
private:
_Ret (_Tp::*_M_f)() const;
};
/// One of the @link memory_adaptors adaptors for member
/// pointers@endlink.
template<typename _Ret, typename _Tp, typename _Arg>
class mem_fun1_t : public binary_function<_Tp*, _Arg, _Ret>
{
public:
explicit
mem_fun1_t(_Ret (_Tp::*__pf)(_Arg))
: _M_f(__pf) { }
_Ret
operator()(_Tp* __p, _Arg __x) const
{ return (__p->*_M_f)(__x); }
private:
_Ret (_Tp::*_M_f)(_Arg);
};
/// One of the @link memory_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>
{
public:
explicit
const_mem_fun1_t(_Ret (_Tp::*__pf)(_Arg) const)
: _M_f(__pf) { }
_Ret
operator()(const _Tp* __p, _Arg __x) const
{ return (__p->*_M_f)(__x); }
private:
_Ret (_Tp::*_M_f)(_Arg) const;
};
/// One of the @link memory_adaptors adaptors for member
/// pointers@endlink.
template<typename _Ret, typename _Tp, typename _Arg>
class mem_fun1_ref_t : public binary_function<_Tp, _Arg, _Ret>
{
public:
explicit
mem_fun1_ref_t(_Ret (_Tp::*__pf)(_Arg))
: _M_f(__pf) { }
_Ret
operator()(_Tp& __r, _Arg __x) const
{ return (__r.*_M_f)(__x); }
private:
_Ret (_Tp::*_M_f)(_Arg);
};
/// One of the @link memory_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>
{
public:
explicit
const_mem_fun1_ref_t(_Ret (_Tp::*__pf)(_Arg) const)
: _M_f(__pf) { }
_Ret
operator()(const _Tp& __r, _Arg __x) const
{ return (__r.*_M_f)(__x); }
private:
_Ret (_Tp::*_M_f)(_Arg) const;
};
// Mem_fun adaptor helper functions. There are only two:
// mem_fun and mem_fun_ref.
template<typename _Ret, typename _Tp>
inline mem_fun_t<_Ret, _Tp>
mem_fun(_Ret (_Tp::*__f)())
{ return mem_fun_t<_Ret, _Tp>(__f); }
template<typename _Ret, typename _Tp>
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>
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>
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>
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>
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>
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>
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); }
/** @} */
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#if (__cplusplus < 201103L) || _GLIBCXX_USE_DEPRECATED
# include <backward/binders.h>
#endif
#endif /* _STL_FUNCTION_H */