396 lines
14 KiB
C++
396 lines
14 KiB
C++
// Functional extensions -*- C++ -*-
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// Copyright (C) 2002 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 2, 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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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING. If not, write to the Free
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// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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// USA.
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// As a special exception, you may use this file as part of a free software
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// library without restriction. Specifically, if other files instantiate
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// templates or use macros or inline functions from this file, or you compile
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// this file and link it with other files to produce an executable, this
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// file does not by itself cause the resulting executable to be covered by
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// the GNU General Public License. This exception does not however
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// invalidate any other reasons why the executable file might be covered by
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// the GNU General Public License.
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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
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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 ext/functional
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* This file is a GNU extension to the Standard C++ Library (possibly
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* containing extensions from the HP/SGI STL subset). You should only
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* include this header if you are using GCC 3 or later.
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*/
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#ifndef _EXT_FUNCTIONAL
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#define _EXT_FUNCTIONAL
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#pragma GCC system_header
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#include <functional>
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namespace __gnu_cxx
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{
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using std::unary_function;
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using std::binary_function;
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using std::mem_fun1_t;
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using std::const_mem_fun1_t;
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using std::mem_fun1_ref_t;
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using std::const_mem_fun1_ref_t;
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/** The @c identity_element functions are not part of the C++ standard; SGI
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* provided them as an extension. Its argument is an operation, and its
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* return value is the identity element for that operation. It is overloaded
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* for addition and multiplication, and you can overload it for your own
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* nefarious operations.
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*
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* @addtogroup SGIextensions
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* @{
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*/
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Tp> inline _Tp identity_element(std::plus<_Tp>) {
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return _Tp(0);
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}
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Tp> inline _Tp identity_element(std::multiplies<_Tp>) {
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return _Tp(1);
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}
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/** @} */
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/** As an extension to the binders, SGI provided composition functors and
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* wrapper functions to aid in their creation. The @c unary_compose
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* functor is constructed from two functions/functors, @c f and @c g.
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* Calling @c operator() with a single argument @c x returns @c f(g(x)).
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* The function @c compose1 takes the two functions and constructs a
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* @c unary_compose variable for you.
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*
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* @c binary_compose is constructed from three functors, @c f, @c g1,
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* and @c g2. Its @c operator() returns @c f(g1(x),g2(x)). The function
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* @compose2 takes f, g1, and g2, and constructs the @c binary_compose
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* instance for you. For example, if @c f returns an int, then
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* \code
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* int answer = (compose2(f,g1,g2))(x);
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* \endcode
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* is equivalent to
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* \code
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* int temp1 = g1(x);
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* int temp2 = g2(x);
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* int answer = f(temp1,temp2);
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* \endcode
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* But the first form is more compact, and can be passed around as a
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* functor to other algorithms.
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*
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* @addtogroup SGIextensions
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* @{
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*/
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Operation1, class _Operation2>
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class unary_compose
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: public unary_function<typename _Operation2::argument_type,
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typename _Operation1::result_type>
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{
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protected:
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_Operation1 _M_fn1;
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_Operation2 _M_fn2;
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public:
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unary_compose(const _Operation1& __x, const _Operation2& __y)
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: _M_fn1(__x), _M_fn2(__y) {}
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typename _Operation1::result_type
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operator()(const typename _Operation2::argument_type& __x) const {
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return _M_fn1(_M_fn2(__x));
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}
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};
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Operation1, class _Operation2>
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inline unary_compose<_Operation1,_Operation2>
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compose1(const _Operation1& __fn1, const _Operation2& __fn2)
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{
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return unary_compose<_Operation1,_Operation2>(__fn1, __fn2);
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}
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Operation1, class _Operation2, class _Operation3>
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class binary_compose
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: public unary_function<typename _Operation2::argument_type,
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typename _Operation1::result_type> {
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protected:
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_Operation1 _M_fn1;
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_Operation2 _M_fn2;
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_Operation3 _M_fn3;
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public:
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binary_compose(const _Operation1& __x, const _Operation2& __y,
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const _Operation3& __z)
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: _M_fn1(__x), _M_fn2(__y), _M_fn3(__z) { }
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typename _Operation1::result_type
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operator()(const typename _Operation2::argument_type& __x) const {
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return _M_fn1(_M_fn2(__x), _M_fn3(__x));
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}
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};
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Operation1, class _Operation2, class _Operation3>
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inline binary_compose<_Operation1, _Operation2, _Operation3>
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compose2(const _Operation1& __fn1, const _Operation2& __fn2,
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const _Operation3& __fn3)
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{
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return binary_compose<_Operation1,_Operation2,_Operation3>
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(__fn1, __fn2, __fn3);
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}
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/** @} */
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/** As an extension, SGI provided a functor called @c identity. When a
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* functor is required but no operations are desired, this can be used as a
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* pass-through. Its @c operator() returns its argument unchanged.
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*
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* @addtogroup SGIextensions
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*/
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template <class _Tp> struct identity : public std::_Identity<_Tp> {};
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/** @c select1st and @c select2nd are extensions provided by SGI. Their
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* @c operator()s
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* take a @c std::pair as an argument, and return either the first member
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* or the second member, respectively. They can be used (especially with
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* the composition functors) to "strip" data from a sequence before
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* performing the remainder of an algorithm.
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*
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* @addtogroup SGIextensions
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* @{
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*/
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Pair> struct select1st : public std::_Select1st<_Pair> {};
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Pair> struct select2nd : public std::_Select2nd<_Pair> {};
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/** @} */
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// extension documented next
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template <class _Arg1, class _Arg2>
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struct _Project1st : public binary_function<_Arg1, _Arg2, _Arg1> {
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_Arg1 operator()(const _Arg1& __x, const _Arg2&) const { return __x; }
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};
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template <class _Arg1, class _Arg2>
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struct _Project2nd : public binary_function<_Arg1, _Arg2, _Arg2> {
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_Arg2 operator()(const _Arg1&, const _Arg2& __y) const { return __y; }
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};
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/** The @c operator() of the @c project1st functor takes two arbitrary
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* arguments and returns the first one, while @c project2nd returns the
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* second one. They are extensions provided by SGI.
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*
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* @addtogroup SGIextensions
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* @{
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*/
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Arg1, class _Arg2>
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struct project1st : public _Project1st<_Arg1, _Arg2> {};
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Arg1, class _Arg2>
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struct project2nd : public _Project2nd<_Arg1, _Arg2> {};
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/** @} */
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// extension documented next
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template <class _Result>
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struct _Constant_void_fun {
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typedef _Result result_type;
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result_type _M_val;
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_Constant_void_fun(const result_type& __v) : _M_val(__v) {}
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const result_type& operator()() const { return _M_val; }
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};
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template <class _Result, class _Argument>
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struct _Constant_unary_fun {
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typedef _Argument argument_type;
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typedef _Result result_type;
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result_type _M_val;
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_Constant_unary_fun(const result_type& __v) : _M_val(__v) {}
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const result_type& operator()(const _Argument&) const { return _M_val; }
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};
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template <class _Result, class _Arg1, class _Arg2>
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struct _Constant_binary_fun {
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typedef _Arg1 first_argument_type;
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typedef _Arg2 second_argument_type;
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typedef _Result result_type;
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_Result _M_val;
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_Constant_binary_fun(const _Result& __v) : _M_val(__v) {}
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const result_type& operator()(const _Arg1&, const _Arg2&) const {
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return _M_val;
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}
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};
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/** These three functors are each constructed from a single arbitrary
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* variable/value. Later, their @c operator()s completely ignore any
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* arguments passed, and return the stored value.
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* - @c constant_void_fun's @c operator() takes no arguments
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* - @c constant_unary_fun's @c operator() takes one argument (ignored)
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* - @c constant_binary_fun's @c operator() takes two arguments (ignored)
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*
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* The helper creator functions @c constant0, @c constant1, and
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* @c constant2 each take a "result" argument and construct variables of
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* the appropriate functor type.
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*
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* @addtogroup SGIextensions
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* @{
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*/
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Result>
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struct constant_void_fun : public _Constant_void_fun<_Result> {
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constant_void_fun(const _Result& __v) : _Constant_void_fun<_Result>(__v) {}
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};
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Result,
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class _Argument = _Result>
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struct constant_unary_fun : public _Constant_unary_fun<_Result, _Argument>
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{
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constant_unary_fun(const _Result& __v)
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: _Constant_unary_fun<_Result, _Argument>(__v) {}
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};
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Result,
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class _Arg1 = _Result,
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class _Arg2 = _Arg1>
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struct constant_binary_fun
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: public _Constant_binary_fun<_Result, _Arg1, _Arg2>
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{
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constant_binary_fun(const _Result& __v)
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: _Constant_binary_fun<_Result, _Arg1, _Arg2>(__v) {}
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};
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Result>
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inline constant_void_fun<_Result> constant0(const _Result& __val)
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{
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return constant_void_fun<_Result>(__val);
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}
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Result>
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inline constant_unary_fun<_Result,_Result> constant1(const _Result& __val)
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{
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return constant_unary_fun<_Result,_Result>(__val);
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}
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/// An \link SGIextensions SGI extension \endlink.
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template <class _Result>
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inline constant_binary_fun<_Result,_Result,_Result>
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constant2(const _Result& __val)
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{
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return constant_binary_fun<_Result,_Result,_Result>(__val);
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}
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/** @} */
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/** The @c subtractive_rng class is documented on
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* <a href="http://www.sgi.com/tech/stl/">SGI's site</a>.
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* Note that this code assumes that @c int is 32 bits.
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*
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* @ingroup SGIextensions
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*/
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class subtractive_rng : public unary_function<unsigned int, unsigned int> {
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private:
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unsigned int _M_table[55];
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size_t _M_index1;
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size_t _M_index2;
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public:
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/// Returns a number less than the argument.
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unsigned int operator()(unsigned int __limit) {
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_M_index1 = (_M_index1 + 1) % 55;
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_M_index2 = (_M_index2 + 1) % 55;
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_M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2];
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return _M_table[_M_index1] % __limit;
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}
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void _M_initialize(unsigned int __seed)
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{
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unsigned int __k = 1;
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_M_table[54] = __seed;
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size_t __i;
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for (__i = 0; __i < 54; __i++) {
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size_t __ii = (21 * (__i + 1) % 55) - 1;
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_M_table[__ii] = __k;
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__k = __seed - __k;
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__seed = _M_table[__ii];
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}
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for (int __loop = 0; __loop < 4; __loop++) {
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for (__i = 0; __i < 55; __i++)
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_M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55];
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}
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_M_index1 = 0;
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_M_index2 = 31;
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}
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/// Ctor allowing you to initialize the seed.
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subtractive_rng(unsigned int __seed) { _M_initialize(__seed); }
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/// Default ctor; initializes its state with some number you don't see.
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subtractive_rng() { _M_initialize(161803398u); }
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};
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// Mem_fun adaptor helper functions mem_fun1 and mem_fun1_ref,
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// provided for backward compatibility, they are no longer part of
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// the C++ standard.
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template <class _Ret, class _Tp, class _Arg>
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inline mem_fun1_t<_Ret,_Tp,_Arg> mem_fun1(_Ret (_Tp::*__f)(_Arg))
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{ return mem_fun1_t<_Ret,_Tp,_Arg>(__f); }
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template <class _Ret, class _Tp, class _Arg>
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inline const_mem_fun1_t<_Ret,_Tp,_Arg> mem_fun1(_Ret (_Tp::*__f)(_Arg) const)
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{ return const_mem_fun1_t<_Ret,_Tp,_Arg>(__f); }
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template <class _Ret, class _Tp, class _Arg>
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inline mem_fun1_ref_t<_Ret,_Tp,_Arg> mem_fun1_ref(_Ret (_Tp::*__f)(_Arg))
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{ return mem_fun1_ref_t<_Ret,_Tp,_Arg>(__f); }
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template <class _Ret, class _Tp, class _Arg>
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inline const_mem_fun1_ref_t<_Ret,_Tp,_Arg>
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mem_fun1_ref(_Ret (_Tp::*__f)(_Arg) const)
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{ return const_mem_fun1_ref_t<_Ret,_Tp,_Arg>(__f); }
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} // namespace __gnu_cxx
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#endif /* _EXT_FUNCTIONAL */
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