169 lines
6.4 KiB
C++
169 lines
6.4 KiB
C++
// Functor implementations -*- C++ -*-
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// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009
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// Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/*
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*
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* Copyright (c) 1994
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* Hewlett-Packard Company
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Hewlett-Packard Company makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*
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*
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* Copyright (c) 1996-1998
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* Silicon Graphics Computer Systems, Inc.
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*
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* Permission to use, copy, modify, distribute and sell this software
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* and its documentation for any purpose is hereby granted without fee,
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* provided that the above copyright notice appear in all copies and
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* that both that copyright notice and this permission notice appear
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* in supporting documentation. Silicon Graphics makes no
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* representations about the suitability of this software for any
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* purpose. It is provided "as is" without express or implied warranty.
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*/
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/** @file backward/binders.h
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* This is an internal header file, included by other library headers.
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* You should not attempt to use it directly.
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*/
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#ifndef _GLIBCXX_BINDERS_H
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#define _GLIBCXX_BINDERS_H 1
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_GLIBCXX_BEGIN_NAMESPACE(std)
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// 20.3.6 binders
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/** @defgroup binders Binder Classes
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* @ingroup functors
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*
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* Binders turn functions/functors with two arguments into functors with
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* a single argument, storing an argument to be applied later. For
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* example, a variable @c B of type @c binder1st is constructed from a
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* functor @c f and an argument @c x. Later, B's @c operator() is called
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* with a single argument @c y. The return value is the value of @c f(x,y).
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* @c B can be "called" with various arguments (y1, y2, ...) and will in
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* turn call @c f(x,y1), @c f(x,y2), ...
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*
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* The function @c bind1st is provided to save some typing. It takes the
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* function and an argument as parameters, and returns an instance of
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* @c binder1st.
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*
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* The type @c binder2nd and its creator function @c bind2nd do the same
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* thing, but the stored argument is passed as the second parameter instead
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* of the first, e.g., @c bind2nd(std::minus<float>,1.3) will create a
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* functor whose @c operator() accepts a floating-point number, subtracts
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* 1.3 from it, and returns the result. (If @c bind1st had been used,
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* the functor would perform "1.3 - x" instead.
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*
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* Creator-wrapper functions like @c bind1st are intended to be used in
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* calling algorithms. Their return values will be temporary objects.
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* (The goal is to not require you to type names like
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* @c std::binder1st<std::plus<int>> for declaring a variable to hold the
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* return value from @c bind1st(std::plus<int>,5).
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*
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* These become more useful when combined with the composition functions.
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*
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* @{
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*/
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/// One of the @link binders binder functors@endlink.
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template<typename _Operation>
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class binder1st
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: public unary_function<typename _Operation::second_argument_type,
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typename _Operation::result_type>
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{
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protected:
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_Operation op;
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typename _Operation::first_argument_type value;
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public:
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binder1st(const _Operation& __x,
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const typename _Operation::first_argument_type& __y)
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: op(__x), value(__y) { }
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typename _Operation::result_type
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operator()(const typename _Operation::second_argument_type& __x) const
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{ return op(value, __x); }
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 109. Missing binders for non-const sequence elements
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typename _Operation::result_type
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operator()(typename _Operation::second_argument_type& __x) const
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{ return op(value, __x); }
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} _GLIBCXX_DEPRECATED_ATTR;
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/// One of the @link binders binder functors@endlink.
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template<typename _Operation, typename _Tp>
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inline binder1st<_Operation>
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bind1st(const _Operation& __fn, const _Tp& __x)
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{
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typedef typename _Operation::first_argument_type _Arg1_type;
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return binder1st<_Operation>(__fn, _Arg1_type(__x));
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}
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/// One of the @link binders binder functors@endlink.
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template<typename _Operation>
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class binder2nd
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: public unary_function<typename _Operation::first_argument_type,
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typename _Operation::result_type>
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{
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protected:
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_Operation op;
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typename _Operation::second_argument_type value;
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public:
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binder2nd(const _Operation& __x,
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const typename _Operation::second_argument_type& __y)
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: op(__x), value(__y) { }
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typename _Operation::result_type
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operator()(const typename _Operation::first_argument_type& __x) const
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{ return op(__x, value); }
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// _GLIBCXX_RESOLVE_LIB_DEFECTS
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// 109. Missing binders for non-const sequence elements
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typename _Operation::result_type
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operator()(typename _Operation::first_argument_type& __x) const
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{ return op(__x, value); }
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} _GLIBCXX_DEPRECATED_ATTR;
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/// One of the @link binders binder functors@endlink.
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template<typename _Operation, typename _Tp>
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inline binder2nd<_Operation>
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bind2nd(const _Operation& __fn, const _Tp& __x)
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{
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typedef typename _Operation::second_argument_type _Arg2_type;
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return binder2nd<_Operation>(__fn, _Arg2_type(__x));
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}
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/** @} */
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_GLIBCXX_END_NAMESPACE
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#endif /* _GLIBCXX_BINDERS_H */
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