// Functor implementations -*- C++ -*- // Copyright (C) 2001-2020 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) 1996-1998 * 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 backward/binders.h * This is an internal header file, included by other library headers. * Do not attempt to use it directly. @headername{functional} */ #ifndef _BACKWARD_BINDERS_H #define _BACKWARD_BINDERS_H 1 // Suppress deprecated warning for this file. #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wdeprecated-declarations" namespace std _GLIBCXX_VISIBILITY(default) { _GLIBCXX_BEGIN_NAMESPACE_VERSION // 20.3.6 binders /** @defgroup binders Binder Classes * @ingroup functors * * Binders turn functions/functors with two arguments into functors * with a single argument, storing an argument to be applied later. * For example, a variable @c B of type @c binder1st is constructed * from a functor @c f and an argument @c x. Later, B's @c * operator() is called with a single argument @c y. The return * value is the value of @c f(x,y). @c B can be @a called with * various arguments (y1, y2, ...) and will in turn call @c * f(x,y1), @c f(x,y2), ... * * The function @c bind1st is provided to save some typing. It takes the * function and an argument as parameters, and returns an instance of * @c binder1st. * * The type @c binder2nd and its creator function @c bind2nd do the same * thing, but the stored argument is passed as the second parameter instead * of the first, e.g., @c bind2nd(std::minus<float>(),1.3) will create a * functor whose @c operator() accepts a floating-point number, subtracts * 1.3 from it, and returns the result. (If @c bind1st had been used, * the functor would perform <em>1.3 - x</em> instead. * * Creator-wrapper functions like @c bind1st are intended to be used in * calling algorithms. Their return values will be temporary objects. * (The goal is to not require you to type names like * @c std::binder1st<std::plus<int>> for declaring a variable to hold the * return value from @c bind1st(std::plus<int>(),5). * * These become more useful when combined with the composition functions. * * These functions are deprecated in C++11 and can be replaced by * @c std::bind (or @c std::tr1::bind) which is more powerful and flexible, * supporting functions with any number of arguments. Uses of @c bind1st * can be replaced by @c std::bind(f, x, std::placeholders::_1) and * @c bind2nd by @c std::bind(f, std::placeholders::_1, x). * @{ */ /// One of the @link binders binder functors@endlink. template<typename _Operation> class binder1st : public unary_function<typename _Operation::second_argument_type, typename _Operation::result_type> { protected: _Operation op; typename _Operation::first_argument_type value; public: binder1st(const _Operation& __x, const typename _Operation::first_argument_type& __y) : op(__x), value(__y) { } typename _Operation::result_type operator()(const typename _Operation::second_argument_type& __x) const { return op(value, __x); } // _GLIBCXX_RESOLVE_LIB_DEFECTS // 109. Missing binders for non-const sequence elements typename _Operation::result_type operator()(typename _Operation::second_argument_type& __x) const { return op(value, __x); } } _GLIBCXX_DEPRECATED; /// One of the @link binders binder functors@endlink. template<typename _Operation, typename _Tp> inline binder1st<_Operation> bind1st(const _Operation& __fn, const _Tp& __x) { typedef typename _Operation::first_argument_type _Arg1_type; return binder1st<_Operation>(__fn, _Arg1_type(__x)); } /// One of the @link binders binder functors@endlink. template<typename _Operation> class binder2nd : public unary_function<typename _Operation::first_argument_type, typename _Operation::result_type> { protected: _Operation op; typename _Operation::second_argument_type value; public: binder2nd(const _Operation& __x, const typename _Operation::second_argument_type& __y) : op(__x), value(__y) { } typename _Operation::result_type operator()(const typename _Operation::first_argument_type& __x) const { return op(__x, value); } // _GLIBCXX_RESOLVE_LIB_DEFECTS // 109. Missing binders for non-const sequence elements typename _Operation::result_type operator()(typename _Operation::first_argument_type& __x) const { return op(__x, value); } } _GLIBCXX_DEPRECATED; /// One of the @link binders binder functors@endlink. template<typename _Operation, typename _Tp> inline binder2nd<_Operation> bind2nd(const _Operation& __fn, const _Tp& __x) { typedef typename _Operation::second_argument_type _Arg2_type; return binder2nd<_Operation>(__fn, _Arg2_type(__x)); } /** @} */ _GLIBCXX_END_NAMESPACE_VERSION } // namespace #pragma GCC diagnostic pop #endif /* _BACKWARD_BINDERS_H */