functional revision 132720
1// Functional extensions -*- C++ -*- 2 3// Copyright (C) 2002 Free Software Foundation, Inc. 4// 5// This file is part of the GNU ISO C++ Library. This library is free 6// software; you can redistribute it and/or modify it under the 7// terms of the GNU General Public License as published by the 8// Free Software Foundation; either version 2, or (at your option) 9// any later version. 10 11// This library is distributed in the hope that it will be useful, 12// but WITHOUT ANY WARRANTY; without even the implied warranty of 13// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14// GNU General Public License for more details. 15 16// You should have received a copy of the GNU General Public License along 17// with this library; see the file COPYING. If not, write to the Free 18// Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, 19// USA. 20 21// As a special exception, you may use this file as part of a free software 22// library without restriction. Specifically, if other files instantiate 23// templates or use macros or inline functions from this file, or you compile 24// this file and link it with other files to produce an executable, this 25// file does not by itself cause the resulting executable to be covered by 26// the GNU General Public License. This exception does not however 27// invalidate any other reasons why the executable file might be covered by 28// the GNU General Public License. 29 30/* 31 * 32 * Copyright (c) 1994 33 * Hewlett-Packard Company 34 * 35 * Permission to use, copy, modify, distribute and sell this software 36 * and its documentation for any purpose is hereby granted without fee, 37 * provided that the above copyright notice appear in all copies and 38 * that both that copyright notice and this permission notice appear 39 * in supporting documentation. Hewlett-Packard Company makes no 40 * representations about the suitability of this software for any 41 * purpose. It is provided "as is" without express or implied warranty. 42 * 43 * 44 * Copyright (c) 1996 45 * Silicon Graphics Computer Systems, Inc. 46 * 47 * Permission to use, copy, modify, distribute and sell this software 48 * and its documentation for any purpose is hereby granted without fee, 49 * provided that the above copyright notice appear in all copies and 50 * that both that copyright notice and this permission notice appear 51 * in supporting documentation. Silicon Graphics makes no 52 * representations about the suitability of this software for any 53 * purpose. It is provided "as is" without express or implied warranty. 54 */ 55 56/** @file ext/functional 57 * This file is a GNU extension to the Standard C++ Library (possibly 58 * containing extensions from the HP/SGI STL subset). You should only 59 * include this header if you are using GCC 3 or later. 60 */ 61 62#ifndef _EXT_FUNCTIONAL 63#define _EXT_FUNCTIONAL 1 64 65#pragma GCC system_header 66 67#include <functional> 68 69namespace __gnu_cxx 70{ 71using std::unary_function; 72using std::binary_function; 73using std::mem_fun1_t; 74using std::const_mem_fun1_t; 75using std::mem_fun1_ref_t; 76using std::const_mem_fun1_ref_t; 77 78/** The @c identity_element functions are not part of the C++ standard; SGI 79 * provided them as an extension. Its argument is an operation, and its 80 * return value is the identity element for that operation. It is overloaded 81 * for addition and multiplication, and you can overload it for your own 82 * nefarious operations. 83 * 84 * @addtogroup SGIextensions 85 * @{ 86*/ 87/// An \link SGIextensions SGI extension \endlink. 88template <class _Tp> inline _Tp identity_element(std::plus<_Tp>) { 89 return _Tp(0); 90} 91/// An \link SGIextensions SGI extension \endlink. 92template <class _Tp> inline _Tp identity_element(std::multiplies<_Tp>) { 93 return _Tp(1); 94} 95/** @} */ 96 97/** As an extension to the binders, SGI provided composition functors and 98 * wrapper functions to aid in their creation. The @c unary_compose 99 * functor is constructed from two functions/functors, @c f and @c g. 100 * Calling @c operator() with a single argument @c x returns @c f(g(x)). 101 * The function @c compose1 takes the two functions and constructs a 102 * @c unary_compose variable for you. 103 * 104 * @c binary_compose is constructed from three functors, @c f, @c g1, 105 * and @c g2. Its @c operator() returns @c f(g1(x),g2(x)). The function 106 * @compose2 takes f, g1, and g2, and constructs the @c binary_compose 107 * instance for you. For example, if @c f returns an int, then 108 * \code 109 * int answer = (compose2(f,g1,g2))(x); 110 * \endcode 111 * is equivalent to 112 * \code 113 * int temp1 = g1(x); 114 * int temp2 = g2(x); 115 * int answer = f(temp1,temp2); 116 * \endcode 117 * But the first form is more compact, and can be passed around as a 118 * functor to other algorithms. 119 * 120 * @addtogroup SGIextensions 121 * @{ 122*/ 123/// An \link SGIextensions SGI extension \endlink. 124template <class _Operation1, class _Operation2> 125class unary_compose 126 : public unary_function<typename _Operation2::argument_type, 127 typename _Operation1::result_type> 128{ 129protected: 130 _Operation1 _M_fn1; 131 _Operation2 _M_fn2; 132public: 133 unary_compose(const _Operation1& __x, const _Operation2& __y) 134 : _M_fn1(__x), _M_fn2(__y) {} 135 typename _Operation1::result_type 136 operator()(const typename _Operation2::argument_type& __x) const { 137 return _M_fn1(_M_fn2(__x)); 138 } 139}; 140 141/// An \link SGIextensions SGI extension \endlink. 142template <class _Operation1, class _Operation2> 143inline unary_compose<_Operation1,_Operation2> 144compose1(const _Operation1& __fn1, const _Operation2& __fn2) 145{ 146 return unary_compose<_Operation1,_Operation2>(__fn1, __fn2); 147} 148 149/// An \link SGIextensions SGI extension \endlink. 150template <class _Operation1, class _Operation2, class _Operation3> 151class binary_compose 152 : public unary_function<typename _Operation2::argument_type, 153 typename _Operation1::result_type> { 154protected: 155 _Operation1 _M_fn1; 156 _Operation2 _M_fn2; 157 _Operation3 _M_fn3; 158public: 159 binary_compose(const _Operation1& __x, const _Operation2& __y, 160 const _Operation3& __z) 161 : _M_fn1(__x), _M_fn2(__y), _M_fn3(__z) { } 162 typename _Operation1::result_type 163 operator()(const typename _Operation2::argument_type& __x) const { 164 return _M_fn1(_M_fn2(__x), _M_fn3(__x)); 165 } 166}; 167 168/// An \link SGIextensions SGI extension \endlink. 169template <class _Operation1, class _Operation2, class _Operation3> 170inline binary_compose<_Operation1, _Operation2, _Operation3> 171compose2(const _Operation1& __fn1, const _Operation2& __fn2, 172 const _Operation3& __fn3) 173{ 174 return binary_compose<_Operation1,_Operation2,_Operation3> 175 (__fn1, __fn2, __fn3); 176} 177/** @} */ 178 179/** As an extension, SGI provided a functor called @c identity. When a 180 * functor is required but no operations are desired, this can be used as a 181 * pass-through. Its @c operator() returns its argument unchanged. 182 * 183 * @addtogroup SGIextensions 184*/ 185template <class _Tp> struct identity : public std::_Identity<_Tp> {}; 186 187/** @c select1st and @c select2nd are extensions provided by SGI. Their 188 * @c operator()s 189 * take a @c std::pair as an argument, and return either the first member 190 * or the second member, respectively. They can be used (especially with 191 * the composition functors) to "strip" data from a sequence before 192 * performing the remainder of an algorithm. 193 * 194 * @addtogroup SGIextensions 195 * @{ 196*/ 197/// An \link SGIextensions SGI extension \endlink. 198template <class _Pair> struct select1st : public std::_Select1st<_Pair> {}; 199/// An \link SGIextensions SGI extension \endlink. 200template <class _Pair> struct select2nd : public std::_Select2nd<_Pair> {}; 201/** @} */ 202 203// extension documented next 204template <class _Arg1, class _Arg2> 205struct _Project1st : public binary_function<_Arg1, _Arg2, _Arg1> { 206 _Arg1 operator()(const _Arg1& __x, const _Arg2&) const { return __x; } 207}; 208 209template <class _Arg1, class _Arg2> 210struct _Project2nd : public binary_function<_Arg1, _Arg2, _Arg2> { 211 _Arg2 operator()(const _Arg1&, const _Arg2& __y) const { return __y; } 212}; 213 214/** The @c operator() of the @c project1st functor takes two arbitrary 215 * arguments and returns the first one, while @c project2nd returns the 216 * second one. They are extensions provided by SGI. 217 * 218 * @addtogroup SGIextensions 219 * @{ 220*/ 221 222/// An \link SGIextensions SGI extension \endlink. 223template <class _Arg1, class _Arg2> 224struct project1st : public _Project1st<_Arg1, _Arg2> {}; 225 226/// An \link SGIextensions SGI extension \endlink. 227template <class _Arg1, class _Arg2> 228struct project2nd : public _Project2nd<_Arg1, _Arg2> {}; 229/** @} */ 230 231// extension documented next 232template <class _Result> 233struct _Constant_void_fun { 234 typedef _Result result_type; 235 result_type _M_val; 236 237 _Constant_void_fun(const result_type& __v) : _M_val(__v) {} 238 const result_type& operator()() const { return _M_val; } 239}; 240 241template <class _Result, class _Argument> 242struct _Constant_unary_fun { 243 typedef _Argument argument_type; 244 typedef _Result result_type; 245 result_type _M_val; 246 247 _Constant_unary_fun(const result_type& __v) : _M_val(__v) {} 248 const result_type& operator()(const _Argument&) const { return _M_val; } 249}; 250 251template <class _Result, class _Arg1, class _Arg2> 252struct _Constant_binary_fun { 253 typedef _Arg1 first_argument_type; 254 typedef _Arg2 second_argument_type; 255 typedef _Result result_type; 256 _Result _M_val; 257 258 _Constant_binary_fun(const _Result& __v) : _M_val(__v) {} 259 const result_type& operator()(const _Arg1&, const _Arg2&) const { 260 return _M_val; 261 } 262}; 263 264/** These three functors are each constructed from a single arbitrary 265 * variable/value. Later, their @c operator()s completely ignore any 266 * arguments passed, and return the stored value. 267 * - @c constant_void_fun's @c operator() takes no arguments 268 * - @c constant_unary_fun's @c operator() takes one argument (ignored) 269 * - @c constant_binary_fun's @c operator() takes two arguments (ignored) 270 * 271 * The helper creator functions @c constant0, @c constant1, and 272 * @c constant2 each take a "result" argument and construct variables of 273 * the appropriate functor type. 274 * 275 * @addtogroup SGIextensions 276 * @{ 277*/ 278/// An \link SGIextensions SGI extension \endlink. 279template <class _Result> 280struct constant_void_fun : public _Constant_void_fun<_Result> { 281 constant_void_fun(const _Result& __v) : _Constant_void_fun<_Result>(__v) {} 282}; 283 284/// An \link SGIextensions SGI extension \endlink. 285template <class _Result, 286 class _Argument = _Result> 287struct constant_unary_fun : public _Constant_unary_fun<_Result, _Argument> 288{ 289 constant_unary_fun(const _Result& __v) 290 : _Constant_unary_fun<_Result, _Argument>(__v) {} 291}; 292 293/// An \link SGIextensions SGI extension \endlink. 294template <class _Result, 295 class _Arg1 = _Result, 296 class _Arg2 = _Arg1> 297struct constant_binary_fun 298 : public _Constant_binary_fun<_Result, _Arg1, _Arg2> 299{ 300 constant_binary_fun(const _Result& __v) 301 : _Constant_binary_fun<_Result, _Arg1, _Arg2>(__v) {} 302}; 303 304/// An \link SGIextensions SGI extension \endlink. 305template <class _Result> 306inline constant_void_fun<_Result> constant0(const _Result& __val) 307{ 308 return constant_void_fun<_Result>(__val); 309} 310 311/// An \link SGIextensions SGI extension \endlink. 312template <class _Result> 313inline constant_unary_fun<_Result,_Result> constant1(const _Result& __val) 314{ 315 return constant_unary_fun<_Result,_Result>(__val); 316} 317 318/// An \link SGIextensions SGI extension \endlink. 319template <class _Result> 320inline constant_binary_fun<_Result,_Result,_Result> 321constant2(const _Result& __val) 322{ 323 return constant_binary_fun<_Result,_Result,_Result>(__val); 324} 325/** @} */ 326 327/** The @c subtractive_rng class is documented on 328 * <a href="http://www.sgi.com/tech/stl/">SGI's site</a>. 329 * Note that this code assumes that @c int is 32 bits. 330 * 331 * @ingroup SGIextensions 332*/ 333class subtractive_rng : public unary_function<unsigned int, unsigned int> { 334private: 335 unsigned int _M_table[55]; 336 size_t _M_index1; 337 size_t _M_index2; 338public: 339 /// Returns a number less than the argument. 340 unsigned int operator()(unsigned int __limit) { 341 _M_index1 = (_M_index1 + 1) % 55; 342 _M_index2 = (_M_index2 + 1) % 55; 343 _M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2]; 344 return _M_table[_M_index1] % __limit; 345 } 346 347 void _M_initialize(unsigned int __seed) 348 { 349 unsigned int __k = 1; 350 _M_table[54] = __seed; 351 size_t __i; 352 for (__i = 0; __i < 54; __i++) { 353 size_t __ii = (21 * (__i + 1) % 55) - 1; 354 _M_table[__ii] = __k; 355 __k = __seed - __k; 356 __seed = _M_table[__ii]; 357 } 358 for (int __loop = 0; __loop < 4; __loop++) { 359 for (__i = 0; __i < 55; __i++) 360 _M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55]; 361 } 362 _M_index1 = 0; 363 _M_index2 = 31; 364 } 365 366 /// Ctor allowing you to initialize the seed. 367 subtractive_rng(unsigned int __seed) { _M_initialize(__seed); } 368 /// Default ctor; initializes its state with some number you don't see. 369 subtractive_rng() { _M_initialize(161803398u); } 370}; 371 372// Mem_fun adaptor helper functions mem_fun1 and mem_fun1_ref, 373// provided for backward compatibility, they are no longer part of 374// the C++ standard. 375 376template <class _Ret, class _Tp, class _Arg> 377inline mem_fun1_t<_Ret,_Tp,_Arg> mem_fun1(_Ret (_Tp::*__f)(_Arg)) 378 { return mem_fun1_t<_Ret,_Tp,_Arg>(__f); } 379 380template <class _Ret, class _Tp, class _Arg> 381inline const_mem_fun1_t<_Ret,_Tp,_Arg> mem_fun1(_Ret (_Tp::*__f)(_Arg) const) 382 { return const_mem_fun1_t<_Ret,_Tp,_Arg>(__f); } 383 384template <class _Ret, class _Tp, class _Arg> 385inline mem_fun1_ref_t<_Ret,_Tp,_Arg> mem_fun1_ref(_Ret (_Tp::*__f)(_Arg)) 386 { return mem_fun1_ref_t<_Ret,_Tp,_Arg>(__f); } 387 388template <class _Ret, class _Tp, class _Arg> 389inline const_mem_fun1_ref_t<_Ret,_Tp,_Arg> 390mem_fun1_ref(_Ret (_Tp::*__f)(_Arg) const) 391 { return const_mem_fun1_ref_t<_Ret,_Tp,_Arg>(__f); } 392} // namespace __gnu_cxx 393 394#endif 395 396