functional revision 169692
1// Functional extensions -*- C++ -*- 2 3// Copyright (C) 2002, 2004, 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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). 59 */ 60 61#ifndef _EXT_FUNCTIONAL 62#define _EXT_FUNCTIONAL 1 63 64#pragma GCC system_header 65 66#include <functional> 67 68_GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) 69 70 using std::size_t; 71 using std::unary_function; 72 using std::binary_function; 73 using std::mem_fun1_t; 74 using std::const_mem_fun1_t; 75 using std::mem_fun1_ref_t; 76 using std::const_mem_fun1_ref_t; 77 78 /** The @c identity_element functions are not part of the C++ 79 * standard; SGI provided them as an extension. Its argument is an 80 * operation, and its return value is the identity element for that 81 * operation. It is overloaded for addition and multiplication, 82 * and you can overload it for your own nefarious operations. 83 * 84 * @addtogroup SGIextensions 85 * @{ 86 */ 87 /// An \link SGIextensions SGI extension \endlink. 88 template <class _Tp> 89 inline _Tp 90 identity_element(std::plus<_Tp>) 91 { return _Tp(0); } 92 93 /// An \link SGIextensions SGI extension \endlink. 94 template <class _Tp> 95 inline _Tp 96 identity_element(std::multiplies<_Tp>) 97 { return _Tp(1); } 98 /** @} */ 99 100 /** As an extension to the binders, SGI provided composition functors and 101 * wrapper functions to aid in their creation. The @c unary_compose 102 * functor is constructed from two functions/functors, @c f and @c g. 103 * Calling @c operator() with a single argument @c x returns @c f(g(x)). 104 * The function @c compose1 takes the two functions and constructs a 105 * @c unary_compose variable for you. 106 * 107 * @c binary_compose is constructed from three functors, @c f, @c g1, 108 * and @c g2. Its @c operator() returns @c f(g1(x),g2(x)). The function 109 * @compose2 takes f, g1, and g2, and constructs the @c binary_compose 110 * instance for you. For example, if @c f returns an int, then 111 * \code 112 * int answer = (compose2(f,g1,g2))(x); 113 * \endcode 114 * is equivalent to 115 * \code 116 * int temp1 = g1(x); 117 * int temp2 = g2(x); 118 * int answer = f(temp1,temp2); 119 * \endcode 120 * But the first form is more compact, and can be passed around as a 121 * functor to other algorithms. 122 * 123 * @addtogroup SGIextensions 124 * @{ 125 */ 126 /// An \link SGIextensions SGI extension \endlink. 127 template <class _Operation1, class _Operation2> 128 class unary_compose 129 : public unary_function<typename _Operation2::argument_type, 130 typename _Operation1::result_type> 131 { 132 protected: 133 _Operation1 _M_fn1; 134 _Operation2 _M_fn2; 135 136 public: 137 unary_compose(const _Operation1& __x, const _Operation2& __y) 138 : _M_fn1(__x), _M_fn2(__y) {} 139 140 typename _Operation1::result_type 141 operator()(const typename _Operation2::argument_type& __x) const 142 { return _M_fn1(_M_fn2(__x)); } 143 }; 144 145 /// An \link SGIextensions SGI extension \endlink. 146 template <class _Operation1, class _Operation2> 147 inline unary_compose<_Operation1, _Operation2> 148 compose1(const _Operation1& __fn1, const _Operation2& __fn2) 149 { return unary_compose<_Operation1,_Operation2>(__fn1, __fn2); } 150 151 /// An \link SGIextensions SGI extension \endlink. 152 template <class _Operation1, class _Operation2, class _Operation3> 153 class binary_compose 154 : public unary_function<typename _Operation2::argument_type, 155 typename _Operation1::result_type> 156 { 157 protected: 158 _Operation1 _M_fn1; 159 _Operation2 _M_fn2; 160 _Operation3 _M_fn3; 161 162 public: 163 binary_compose(const _Operation1& __x, const _Operation2& __y, 164 const _Operation3& __z) 165 : _M_fn1(__x), _M_fn2(__y), _M_fn3(__z) { } 166 167 typename _Operation1::result_type 168 operator()(const typename _Operation2::argument_type& __x) const 169 { return _M_fn1(_M_fn2(__x), _M_fn3(__x)); } 170 }; 171 172 /// An \link SGIextensions SGI extension \endlink. 173 template <class _Operation1, class _Operation2, class _Operation3> 174 inline binary_compose<_Operation1, _Operation2, _Operation3> 175 compose2(const _Operation1& __fn1, const _Operation2& __fn2, 176 const _Operation3& __fn3) 177 { return binary_compose<_Operation1, _Operation2, _Operation3> 178 (__fn1, __fn2, __fn3); } 179 /** @} */ 180 181 /** As an extension, SGI provided a functor called @c identity. When a 182 * functor is required but no operations are desired, this can be used as a 183 * pass-through. Its @c operator() returns its argument unchanged. 184 * 185 * @addtogroup SGIextensions 186 */ 187 template <class _Tp> 188 struct identity : public std::_Identity<_Tp> {}; 189 190 /** @c select1st and @c select2nd are extensions provided by SGI. Their 191 * @c operator()s 192 * take a @c std::pair as an argument, and return either the first member 193 * or the second member, respectively. They can be used (especially with 194 * the composition functors) to "strip" data from a sequence before 195 * performing the remainder of an algorithm. 196 * 197 * @addtogroup SGIextensions 198 * @{ 199 */ 200 /// An \link SGIextensions SGI extension \endlink. 201 template <class _Pair> 202 struct select1st : public std::_Select1st<_Pair> {}; 203 204 /// An \link SGIextensions SGI extension \endlink. 205 template <class _Pair> 206 struct select2nd : public std::_Select2nd<_Pair> {}; 207 /** @} */ 208 209 // extension documented next 210 template <class _Arg1, class _Arg2> 211 struct _Project1st : public binary_function<_Arg1, _Arg2, _Arg1> 212 { 213 _Arg1 214 operator()(const _Arg1& __x, const _Arg2&) const 215 { return __x; } 216 }; 217 218 template <class _Arg1, class _Arg2> 219 struct _Project2nd : public binary_function<_Arg1, _Arg2, _Arg2> 220 { 221 _Arg2 222 operator()(const _Arg1&, const _Arg2& __y) const 223 { return __y; } 224 }; 225 226 /** The @c operator() of the @c project1st functor takes two arbitrary 227 * arguments and returns the first one, while @c project2nd returns the 228 * second one. They are extensions provided by SGI. 229 * 230 * @addtogroup SGIextensions 231 * @{ 232 */ 233 234 /// An \link SGIextensions SGI extension \endlink. 235 template <class _Arg1, class _Arg2> 236 struct project1st : public _Project1st<_Arg1, _Arg2> {}; 237 238 /// An \link SGIextensions SGI extension \endlink. 239 template <class _Arg1, class _Arg2> 240 struct project2nd : public _Project2nd<_Arg1, _Arg2> {}; 241 /** @} */ 242 243 // extension documented next 244 template <class _Result> 245 struct _Constant_void_fun 246 { 247 typedef _Result result_type; 248 result_type _M_val; 249 250 _Constant_void_fun(const result_type& __v) : _M_val(__v) {} 251 252 const result_type& 253 operator()() const 254 { return _M_val; } 255 }; 256 257 template <class _Result, class _Argument> 258 struct _Constant_unary_fun 259 { 260 typedef _Argument argument_type; 261 typedef _Result result_type; 262 result_type _M_val; 263 264 _Constant_unary_fun(const result_type& __v) : _M_val(__v) {} 265 266 const result_type& 267 operator()(const _Argument&) const 268 { return _M_val; } 269 }; 270 271 template <class _Result, class _Arg1, class _Arg2> 272 struct _Constant_binary_fun 273 { 274 typedef _Arg1 first_argument_type; 275 typedef _Arg2 second_argument_type; 276 typedef _Result result_type; 277 _Result _M_val; 278 279 _Constant_binary_fun(const _Result& __v) : _M_val(__v) {} 280 281 const result_type& 282 operator()(const _Arg1&, const _Arg2&) const 283 { return _M_val; } 284 }; 285 286 /** These three functors are each constructed from a single arbitrary 287 * variable/value. Later, their @c operator()s completely ignore any 288 * arguments passed, and return the stored value. 289 * - @c constant_void_fun's @c operator() takes no arguments 290 * - @c constant_unary_fun's @c operator() takes one argument (ignored) 291 * - @c constant_binary_fun's @c operator() takes two arguments (ignored) 292 * 293 * The helper creator functions @c constant0, @c constant1, and 294 * @c constant2 each take a "result" argument and construct variables of 295 * the appropriate functor type. 296 * 297 * @addtogroup SGIextensions 298 * @{ 299 */ 300 /// An \link SGIextensions SGI extension \endlink. 301 template <class _Result> 302 struct constant_void_fun 303 : public _Constant_void_fun<_Result> 304 { 305 constant_void_fun(const _Result& __v) 306 : _Constant_void_fun<_Result>(__v) {} 307 }; 308 309 /// An \link SGIextensions SGI extension \endlink. 310 template <class _Result, class _Argument = _Result> 311 struct constant_unary_fun : public _Constant_unary_fun<_Result, _Argument> 312 { 313 constant_unary_fun(const _Result& __v) 314 : _Constant_unary_fun<_Result, _Argument>(__v) {} 315 }; 316 317 /// An \link SGIextensions SGI extension \endlink. 318 template <class _Result, class _Arg1 = _Result, class _Arg2 = _Arg1> 319 struct constant_binary_fun 320 : public _Constant_binary_fun<_Result, _Arg1, _Arg2> 321 { 322 constant_binary_fun(const _Result& __v) 323 : _Constant_binary_fun<_Result, _Arg1, _Arg2>(__v) {} 324 }; 325 326 /// An \link SGIextensions SGI extension \endlink. 327 template <class _Result> 328 inline constant_void_fun<_Result> 329 constant0(const _Result& __val) 330 { return constant_void_fun<_Result>(__val); } 331 332 /// An \link SGIextensions SGI extension \endlink. 333 template <class _Result> 334 inline constant_unary_fun<_Result, _Result> 335 constant1(const _Result& __val) 336 { return constant_unary_fun<_Result, _Result>(__val); } 337 338 /// An \link SGIextensions SGI extension \endlink. 339 template <class _Result> 340 inline constant_binary_fun<_Result,_Result,_Result> 341 constant2(const _Result& __val) 342 { return constant_binary_fun<_Result, _Result, _Result>(__val); } 343 /** @} */ 344 345 /** The @c subtractive_rng class is documented on 346 * <a href="http://www.sgi.com/tech/stl/">SGI's site</a>. 347 * Note that this code assumes that @c int is 32 bits. 348 * 349 * @ingroup SGIextensions 350 */ 351 class subtractive_rng 352 : public unary_function<unsigned int, unsigned int> 353 { 354 private: 355 unsigned int _M_table[55]; 356 size_t _M_index1; 357 size_t _M_index2; 358 359 public: 360 /// Returns a number less than the argument. 361 unsigned int 362 operator()(unsigned int __limit) 363 { 364 _M_index1 = (_M_index1 + 1) % 55; 365 _M_index2 = (_M_index2 + 1) % 55; 366 _M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2]; 367 return _M_table[_M_index1] % __limit; 368 } 369 370 void 371 _M_initialize(unsigned int __seed) 372 { 373 unsigned int __k = 1; 374 _M_table[54] = __seed; 375 size_t __i; 376 for (__i = 0; __i < 54; __i++) 377 { 378 size_t __ii = (21 * (__i + 1) % 55) - 1; 379 _M_table[__ii] = __k; 380 __k = __seed - __k; 381 __seed = _M_table[__ii]; 382 } 383 for (int __loop = 0; __loop < 4; __loop++) 384 { 385 for (__i = 0; __i < 55; __i++) 386 _M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55]; 387 } 388 _M_index1 = 0; 389 _M_index2 = 31; 390 } 391 392 /// Ctor allowing you to initialize the seed. 393 subtractive_rng(unsigned int __seed) 394 { _M_initialize(__seed); } 395 396 /// Default ctor; initializes its state with some number you don't see. 397 subtractive_rng() 398 { _M_initialize(161803398u); } 399 }; 400 401 // Mem_fun adaptor helper functions mem_fun1 and mem_fun1_ref, 402 // provided for backward compatibility, they are no longer part of 403 // the C++ standard. 404 405 template <class _Ret, class _Tp, class _Arg> 406 inline mem_fun1_t<_Ret, _Tp, _Arg> 407 mem_fun1(_Ret (_Tp::*__f)(_Arg)) 408 { return mem_fun1_t<_Ret, _Tp, _Arg>(__f); } 409 410 template <class _Ret, class _Tp, class _Arg> 411 inline const_mem_fun1_t<_Ret, _Tp, _Arg> 412 mem_fun1(_Ret (_Tp::*__f)(_Arg) const) 413 { return const_mem_fun1_t<_Ret, _Tp, _Arg>(__f); } 414 415 template <class _Ret, class _Tp, class _Arg> 416 inline mem_fun1_ref_t<_Ret, _Tp, _Arg> 417 mem_fun1_ref(_Ret (_Tp::*__f)(_Arg)) 418 { return mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); } 419 420 template <class _Ret, class _Tp, class _Arg> 421 inline const_mem_fun1_ref_t<_Ret, _Tp, _Arg> 422 mem_fun1_ref(_Ret (_Tp::*__f)(_Arg) const) 423 { return const_mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); } 424 425_GLIBCXX_END_NAMESPACE 426 427#endif 428 429