// Functional extensions -*- C++ -*- // Copyright (C) 2002-2020 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