ext/functional
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// Functional extensions -*- C++ -*-
// Copyright (C) 2002-2021 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
* 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 ext/functional
* This file is a GNU extension to the Standard C++ Library (possibly
* containing extensions from the HP/SGI STL subset).
*/
#ifndef _EXT_FUNCTIONAL
#define _EXT_FUNCTIONAL 1
#pragma GCC system_header
#include <functional>
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
/** The @c identity_element functions are not part of the C++
* standard; SGI provided them as an extension. Its argument is an
* operation, and its return value is the identity element for that
* operation. It is overloaded for addition and multiplication,
* and you can overload it for your own nefarious operations.
*
* @addtogroup SGIextensions
* @{
*/
/// An \link SGIextensions SGI extension \endlink.
template <class _Tp>
inline _Tp
identity_element(std::plus<_Tp>)
{ return _Tp(0); }
/// An \link SGIextensions SGI extension \endlink.
template <class _Tp>
inline _Tp
identity_element(std::multiplies<_Tp>)
{ return _Tp(1); }
/** @} */
/** As an extension to the binders, SGI provided composition functors and
* wrapper functions to aid in their creation. The @c unary_compose
* functor is constructed from two functions/functors, @c f and @c g.
* Calling @c operator() with a single argument @c x returns @c f(g(x)).
* The function @c compose1 takes the two functions and constructs a
* @c unary_compose variable for you.
*
* @c binary_compose is constructed from three functors, @c f, @c g1,
* and @c g2. Its @c operator() returns @c f(g1(x),g2(x)). The function
* compose2 takes f, g1, and g2, and constructs the @c binary_compose
* instance for you. For example, if @c f returns an int, then
* \code
* int answer = (compose2(f,g1,g2))(x);
* \endcode
* is equivalent to
* \code
* int temp1 = g1(x);
* int temp2 = g2(x);
* int answer = f(temp1,temp2);
* \endcode
* But the first form is more compact, and can be passed around as a
* functor to other algorithms.
*
* @addtogroup SGIextensions
* @{
*/
/// An \link SGIextensions SGI extension \endlink.
template <class _Operation1, class _Operation2>
class unary_compose
: public std::unary_function<typename _Operation2::argument_type,
typename _Operation1::result_type>
{
protected:
_Operation1 _M_fn1;
_Operation2 _M_fn2;
public:
unary_compose(const _Operation1& __x, const _Operation2& __y)
: _M_fn1(__x), _M_fn2(__y) {}
typename _Operation1::result_type
operator()(const typename _Operation2::argument_type& __x) const
{ return _M_fn1(_M_fn2(__x)); }
};
/// An \link SGIextensions SGI extension \endlink.
template <class _Operation1, class _Operation2>
inline unary_compose<_Operation1, _Operation2>
compose1(const _Operation1& __fn1, const _Operation2& __fn2)
{ return unary_compose<_Operation1,_Operation2>(__fn1, __fn2); }
/// An \link SGIextensions SGI extension \endlink.
template <class _Operation1, class _Operation2, class _Operation3>
class binary_compose
: public std::unary_function<typename _Operation2::argument_type,
typename _Operation1::result_type>
{
protected:
_Operation1 _M_fn1;
_Operation2 _M_fn2;
_Operation3 _M_fn3;
public:
binary_compose(const _Operation1& __x, const _Operation2& __y,
const _Operation3& __z)
: _M_fn1(__x), _M_fn2(__y), _M_fn3(__z) { }
typename _Operation1::result_type
operator()(const typename _Operation2::argument_type& __x) const
{ return _M_fn1(_M_fn2(__x), _M_fn3(__x)); }
};
/// An \link SGIextensions SGI extension \endlink.
template <class _Operation1, class _Operation2, class _Operation3>
inline binary_compose<_Operation1, _Operation2, _Operation3>
compose2(const _Operation1& __fn1, const _Operation2& __fn2,
const _Operation3& __fn3)
{ return binary_compose<_Operation1, _Operation2, _Operation3>
(__fn1, __fn2, __fn3); }
/** @} */
/** As an extension, SGI provided a functor called @c identity. When a
* functor is required but no operations are desired, this can be used as a
* pass-through. Its @c operator() returns its argument unchanged.
*
* @addtogroup SGIextensions
*/
template <class _Tp>
struct identity
: public std::_Identity<_Tp> {};
/** @c select1st and @c select2nd are extensions provided by SGI. Their
* @c operator()s
* take a @c std::pair as an argument, and return either the first member
* or the second member, respectively. They can be used (especially with
* the composition functors) to @a strip data from a sequence before
* performing the remainder of an algorithm.
*
* @addtogroup SGIextensions
* @{
*/
/// An \link SGIextensions SGI extension \endlink.
template <class _Pair>
struct select1st
: public std::_Select1st<_Pair> {};
/// An \link SGIextensions SGI extension \endlink.
template <class _Pair>
struct select2nd
: public std::_Select2nd<_Pair> {};
/** @} */
// extension documented next
template <class _Arg1, class _Arg2>
struct _Project1st : public std::binary_function<_Arg1, _Arg2, _Arg1>
{
_Arg1
operator()(const _Arg1& __x, const _Arg2&) const
{ return __x; }
};
template <class _Arg1, class _Arg2>
struct _Project2nd : public std::binary_function<_Arg1, _Arg2, _Arg2>
{
_Arg2
operator()(const _Arg1&, const _Arg2& __y) const
{ return __y; }
};
/** The @c operator() of the @c project1st functor takes two arbitrary
* arguments and returns the first one, while @c project2nd returns the
* second one. They are extensions provided by SGI.
*
* @addtogroup SGIextensions
* @{
*/
/// An \link SGIextensions SGI extension \endlink.
template <class _Arg1, class _Arg2>
struct project1st : public _Project1st<_Arg1, _Arg2> {};
/// An \link SGIextensions SGI extension \endlink.
template <class _Arg1, class _Arg2>
struct project2nd : public _Project2nd<_Arg1, _Arg2> {};
/** @} */
// extension documented next
template <class _Result>
struct _Constant_void_fun
{
typedef _Result result_type;
result_type _M_val;
_Constant_void_fun(const result_type& __v) : _M_val(__v) {}
const result_type&
operator()() const
{ return _M_val; }
};
template <class _Result, class _Argument>
struct _Constant_unary_fun
{
typedef _Argument argument_type;
typedef _Result result_type;
result_type _M_val;
_Constant_unary_fun(const result_type& __v) : _M_val(__v) {}
const result_type&
operator()(const _Argument&) const
{ return _M_val; }
};
template <class _Result, class _Arg1, class _Arg2>
struct _Constant_binary_fun
{
typedef _Arg1 first_argument_type;
typedef _Arg2 second_argument_type;
typedef _Result result_type;
_Result _M_val;
_Constant_binary_fun(const _Result& __v) : _M_val(__v) {}
const result_type&
operator()(const _Arg1&, const _Arg2&) const
{ return _M_val; }
};
/** These three functors are each constructed from a single arbitrary
* variable/value. Later, their @c operator()s completely ignore any
* arguments passed, and return the stored value.
* - @c constant_void_fun's @c operator() takes no arguments
* - @c constant_unary_fun's @c operator() takes one argument (ignored)
* - @c constant_binary_fun's @c operator() takes two arguments (ignored)
*
* The helper creator functions @c constant0, @c constant1, and
* @c constant2 each take a @a result argument and construct variables of
* the appropriate functor type.
*
* @addtogroup SGIextensions
* @{
*/
/// An \link SGIextensions SGI extension \endlink.
template <class _Result>
struct constant_void_fun
: public _Constant_void_fun<_Result>
{
constant_void_fun(const _Result& __v)
: _Constant_void_fun<_Result>(__v) {}
};
/// An \link SGIextensions SGI extension \endlink.
template <class _Result, class _Argument = _Result>
struct constant_unary_fun : public _Constant_unary_fun<_Result, _Argument>
{
constant_unary_fun(const _Result& __v)
: _Constant_unary_fun<_Result, _Argument>(__v) {}
};
/// An \link SGIextensions SGI extension \endlink.
template <class _Result, class _Arg1 = _Result, class _Arg2 = _Arg1>
struct constant_binary_fun
: public _Constant_binary_fun<_Result, _Arg1, _Arg2>
{
constant_binary_fun(const _Result& __v)
: _Constant_binary_fun<_Result, _Arg1, _Arg2>(__v) {}
};
/// An \link SGIextensions SGI extension \endlink.
template <class _Result>
inline constant_void_fun<_Result>
constant0(const _Result& __val)
{ return constant_void_fun<_Result>(__val); }
/// An \link SGIextensions SGI extension \endlink.
template <class _Result>
inline constant_unary_fun<_Result, _Result>
constant1(const _Result& __val)
{ return constant_unary_fun<_Result, _Result>(__val); }
/// An \link SGIextensions SGI extension \endlink.
template <class _Result>
inline constant_binary_fun<_Result,_Result,_Result>
constant2(const _Result& __val)
{ return constant_binary_fun<_Result, _Result, _Result>(__val); }
/** @} */
/** The @c subtractive_rng class is documented on
* <a href="http://www.sgi.com/tech/stl/">SGI's site</a>.
* Note that this code assumes that @c int is 32 bits.
*
* @ingroup SGIextensions
*/
class subtractive_rng
: public std::unary_function<unsigned int, unsigned int>
{
private:
unsigned int _M_table[55];
std::size_t _M_index1;
std::size_t _M_index2;
public:
/// Returns a number less than the argument.
unsigned int
operator()(unsigned int __limit)
{
_M_index1 = (_M_index1 + 1) % 55;
_M_index2 = (_M_index2 + 1) % 55;
_M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2];
return _M_table[_M_index1] % __limit;
}
void
_M_initialize(unsigned int __seed)
{
unsigned int __k = 1;
_M_table[54] = __seed;
std::size_t __i;
for (__i = 0; __i < 54; __i++)
{
std::size_t __ii = (21 * (__i + 1) % 55) - 1;
_M_table[__ii] = __k;
__k = __seed - __k;
__seed = _M_table[__ii];
}
for (int __loop = 0; __loop < 4; __loop++)
{
for (__i = 0; __i < 55; __i++)
_M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55];
}
_M_index1 = 0;
_M_index2 = 31;
}
/// Ctor allowing you to initialize the seed.
subtractive_rng(unsigned int __seed)
{ _M_initialize(__seed); }
/// Default ctor; initializes its state with some number you don't see.
subtractive_rng()
{ _M_initialize(161803398u); }
};
// Mem_fun adaptor helper functions mem_fun1 and mem_fun1_ref,
// provided for backward compatibility, they are no longer part of
// the C++ standard.
template <class _Ret, class _Tp, class _Arg>
inline std::mem_fun1_t<_Ret, _Tp, _Arg>
mem_fun1(_Ret (_Tp::*__f)(_Arg))
{ return std::mem_fun1_t<_Ret, _Tp, _Arg>(__f); }
template <class _Ret, class _Tp, class _Arg>
inline std::const_mem_fun1_t<_Ret, _Tp, _Arg>
mem_fun1(_Ret (_Tp::*__f)(_Arg) const)
{ return std::const_mem_fun1_t<_Ret, _Tp, _Arg>(__f); }
template <class _Ret, class _Tp, class _Arg>
inline std::mem_fun1_ref_t<_Ret, _Tp, _Arg>
mem_fun1_ref(_Ret (_Tp::*__f)(_Arg))
{ return std::mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); }
template <class _Ret, class _Tp, class _Arg>
inline std::const_mem_fun1_ref_t<_Ret, _Tp, _Arg>
mem_fun1_ref(_Ret (_Tp::*__f)(_Arg) const)
{ return std::const_mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); }
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif