1 // Functional extensions -*- C++ -*- 2 3 // Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2009 4 // Free Software Foundation, Inc. 5 // 6 // This file is part of the GNU ISO C++ Library. This library is free 7 // software; you can redistribute it and/or modify it under the 8 // terms of the GNU General Public License as published by the 9 // Free Software Foundation; either version 3, or (at your option) 10 // any later version. 11 12 // This library is distributed in the hope that it will be useful, 13 // but WITHOUT ANY WARRANTY; without even the implied warranty of 14 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 // GNU General Public License for more details. 16 17 // Under Section 7 of GPL version 3, you are granted additional 18 // permissions described in the GCC Runtime Library Exception, version 19 // 3.1, as published by the Free Software Foundation. 20 21 // You should have received a copy of the GNU General Public License and 22 // a copy of the GCC Runtime Library Exception along with this program; 23 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 24 // <http://www.gnu.org/licenses/>. 25 26 /* 27 * 28 * Copyright (c) 1994 29 * Hewlett-Packard Company 30 * 31 * Permission to use, copy, modify, distribute and sell this software 32 * and its documentation for any purpose is hereby granted without fee, 33 * provided that the above copyright notice appear in all copies and 34 * that both that copyright notice and this permission notice appear 35 * in supporting documentation. Hewlett-Packard Company makes no 36 * representations about the suitability of this software for any 37 * purpose. It is provided "as is" without express or implied warranty. 38 * 39 * 40 * Copyright (c) 1996 41 * Silicon Graphics Computer Systems, Inc. 42 * 43 * Permission to use, copy, modify, distribute and sell this software 44 * and its documentation for any purpose is hereby granted without fee, 45 * provided that the above copyright notice appear in all copies and 46 * that both that copyright notice and this permission notice appear 47 * in supporting documentation. Silicon Graphics makes no 48 * representations about the suitability of this software for any 49 * purpose. It is provided "as is" without express or implied warranty. 50 */ 51 52 /** @file ext/functional 53 * This file is a GNU extension to the Standard C++ Library (possibly 54 * containing extensions from the HP/SGI STL subset). 55 */ 56 57 #ifndef _EXT_FUNCTIONAL 58 #define _EXT_FUNCTIONAL 1 59 60 #pragma GCC system_header 61 62 #include <functional> 63 #include <cstddef> 64 65 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx) 66 67 using std::size_t; 68 using std::unary_function; 69 using std::binary_function; 70 using std::mem_fun1_t; 71 using std::const_mem_fun1_t; 72 using std::mem_fun1_ref_t; 73 using std::const_mem_fun1_ref_t; 74 75 /** The @c identity_element functions are not part of the C++ 76 * standard; SGI provided them as an extension. Its argument is an 77 * operation, and its return value is the identity element for that 78 * operation. It is overloaded for addition and multiplication, 79 * and you can overload it for your own nefarious operations. 80 * 81 * @addtogroup SGIextensions 82 * @{ 83 */ 84 /// An \link SGIextensions SGI extension \endlink. 85 template <class _Tp> 86 inline _Tp 87 identity_element(std::plus<_Tp>) 88 { return _Tp(0); } 89 90 /// An \link SGIextensions SGI extension \endlink. 91 template <class _Tp> 92 inline _Tp 93 identity_element(std::multiplies<_Tp>) 94 { return _Tp(1); } 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. 124 template <class _Operation1, class _Operation2> 125 class unary_compose 126 : public unary_function<typename _Operation2::argument_type, 127 typename _Operation1::result_type> 128 { 129 protected: 130 _Operation1 _M_fn1; 131 _Operation2 _M_fn2; 132 133 public: 134 unary_compose(const _Operation1& __x, const _Operation2& __y) 135 : _M_fn1(__x), _M_fn2(__y) {} 136 137 typename _Operation1::result_type 138 operator()(const typename _Operation2::argument_type& __x) const 139 { return _M_fn1(_M_fn2(__x)); } 140 }; 141 142 /// An \link SGIextensions SGI extension \endlink. 143 template <class _Operation1, class _Operation2> 144 inline unary_compose<_Operation1, _Operation2> 145 compose1(const _Operation1& __fn1, const _Operation2& __fn2) 146 { return unary_compose<_Operation1,_Operation2>(__fn1, __fn2); } 147 148 /// An \link SGIextensions SGI extension \endlink. 149 template <class _Operation1, class _Operation2, class _Operation3> 150 class binary_compose 151 : public unary_function<typename _Operation2::argument_type, 152 typename _Operation1::result_type> 153 { 154 protected: 155 _Operation1 _M_fn1; 156 _Operation2 _M_fn2; 157 _Operation3 _M_fn3; 158 159 public: 160 binary_compose(const _Operation1& __x, const _Operation2& __y, 161 const _Operation3& __z) 162 : _M_fn1(__x), _M_fn2(__y), _M_fn3(__z) { } 163 164 typename _Operation1::result_type 165 operator()(const typename _Operation2::argument_type& __x) const 166 { return _M_fn1(_M_fn2(__x), _M_fn3(__x)); } 167 }; 168 169 /// An \link SGIextensions SGI extension \endlink. 170 template <class _Operation1, class _Operation2, class _Operation3> 171 inline binary_compose<_Operation1, _Operation2, _Operation3> 172 compose2(const _Operation1& __fn1, const _Operation2& __fn2, 173 const _Operation3& __fn3) 174 { return binary_compose<_Operation1, _Operation2, _Operation3> 175 (__fn1, __fn2, __fn3); } 176 /** @} */ 177 178 /** As an extension, SGI provided a functor called @c identity. When a 179 * functor is required but no operations are desired, this can be used as a 180 * pass-through. Its @c operator() returns its argument unchanged. 181 * 182 * @addtogroup SGIextensions 183 */ 184 template <class _Tp> 185 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. 198 template <class _Pair> 199 struct select1st : public std::_Select1st<_Pair> {}; 200 201 /// An \link SGIextensions SGI extension \endlink. 202 template <class _Pair> 203 struct select2nd : public std::_Select2nd<_Pair> {}; 204 /** @} */ 205 206 // extension documented next 207 template <class _Arg1, class _Arg2> 208 struct _Project1st : public binary_function<_Arg1, _Arg2, _Arg1> 209 { 210 _Arg1 211 operator()(const _Arg1& __x, const _Arg2&) const 212 { return __x; } 213 }; 214 215 template <class _Arg1, class _Arg2> 216 struct _Project2nd : public binary_function<_Arg1, _Arg2, _Arg2> 217 { 218 _Arg2 219 operator()(const _Arg1&, const _Arg2& __y) const 220 { return __y; } 221 }; 222 223 /** The @c operator() of the @c project1st functor takes two arbitrary 224 * arguments and returns the first one, while @c project2nd returns the 225 * second one. They are extensions provided by SGI. 226 * 227 * @addtogroup SGIextensions 228 * @{ 229 */ 230 231 /// An \link SGIextensions SGI extension \endlink. 232 template <class _Arg1, class _Arg2> 233 struct project1st : public _Project1st<_Arg1, _Arg2> {}; 234 235 /// An \link SGIextensions SGI extension \endlink. 236 template <class _Arg1, class _Arg2> 237 struct project2nd : public _Project2nd<_Arg1, _Arg2> {}; 238 /** @} */ 239 240 // extension documented next 241 template <class _Result> 242 struct _Constant_void_fun 243 { 244 typedef _Result result_type; 245 result_type _M_val; 246 247 _Constant_void_fun(const result_type& __v) : _M_val(__v) {} 248 249 const result_type& 250 operator()() const 251 { return _M_val; } 252 }; 253 254 template <class _Result, class _Argument> 255 struct _Constant_unary_fun 256 { 257 typedef _Argument argument_type; 258 typedef _Result result_type; 259 result_type _M_val; 260 261 _Constant_unary_fun(const result_type& __v) : _M_val(__v) {} 262 263 const result_type& 264 operator()(const _Argument&) const 265 { return _M_val; } 266 }; 267 268 template <class _Result, class _Arg1, class _Arg2> 269 struct _Constant_binary_fun 270 { 271 typedef _Arg1 first_argument_type; 272 typedef _Arg2 second_argument_type; 273 typedef _Result result_type; 274 _Result _M_val; 275 276 _Constant_binary_fun(const _Result& __v) : _M_val(__v) {} 277 278 const result_type& 279 operator()(const _Arg1&, const _Arg2&) const 280 { return _M_val; } 281 }; 282 283 /** These three functors are each constructed from a single arbitrary 284 * variable/value. Later, their @c operator()s completely ignore any 285 * arguments passed, and return the stored value. 286 * - @c constant_void_fun's @c operator() takes no arguments 287 * - @c constant_unary_fun's @c operator() takes one argument (ignored) 288 * - @c constant_binary_fun's @c operator() takes two arguments (ignored) 289 * 290 * The helper creator functions @c constant0, @c constant1, and 291 * @c constant2 each take a "result" argument and construct variables of 292 * the appropriate functor type. 293 * 294 * @addtogroup SGIextensions 295 * @{ 296 */ 297 /// An \link SGIextensions SGI extension \endlink. 298 template <class _Result> 299 struct constant_void_fun 300 : public _Constant_void_fun<_Result> 301 { 302 constant_void_fun(const _Result& __v) 303 : _Constant_void_fun<_Result>(__v) {} 304 }; 305 306 /// An \link SGIextensions SGI extension \endlink. 307 template <class _Result, class _Argument = _Result> 308 struct constant_unary_fun : public _Constant_unary_fun<_Result, _Argument> 309 { 310 constant_unary_fun(const _Result& __v) 311 : _Constant_unary_fun<_Result, _Argument>(__v) {} 312 }; 313 314 /// An \link SGIextensions SGI extension \endlink. 315 template <class _Result, class _Arg1 = _Result, class _Arg2 = _Arg1> 316 struct constant_binary_fun 317 : public _Constant_binary_fun<_Result, _Arg1, _Arg2> 318 { 319 constant_binary_fun(const _Result& __v) 320 : _Constant_binary_fun<_Result, _Arg1, _Arg2>(__v) {} 321 }; 322 323 /// An \link SGIextensions SGI extension \endlink. 324 template <class _Result> 325 inline constant_void_fun<_Result> 326 constant0(const _Result& __val) 327 { return constant_void_fun<_Result>(__val); } 328 329 /// An \link SGIextensions SGI extension \endlink. 330 template <class _Result> 331 inline constant_unary_fun<_Result, _Result> 332 constant1(const _Result& __val) 333 { return constant_unary_fun<_Result, _Result>(__val); } 334 335 /// An \link SGIextensions SGI extension \endlink. 336 template <class _Result> 337 inline constant_binary_fun<_Result,_Result,_Result> 338 constant2(const _Result& __val) 339 { return constant_binary_fun<_Result, _Result, _Result>(__val); } 340 /** @} */ 341 342 /** The @c subtractive_rng class is documented on 343 * <a href="http://www.sgi.com/tech/stl/">SGI's site</a>. 344 * Note that this code assumes that @c int is 32 bits. 345 * 346 * @ingroup SGIextensions 347 */ 348 class subtractive_rng 349 : public unary_function<unsigned int, unsigned int> 350 { 351 private: 352 unsigned int _M_table[55]; 353 size_t _M_index1; 354 size_t _M_index2; 355 356 public: 357 /// Returns a number less than the argument. 358 unsigned int 359 operator()(unsigned int __limit) 360 { 361 _M_index1 = (_M_index1 + 1) % 55; 362 _M_index2 = (_M_index2 + 1) % 55; 363 _M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2]; 364 return _M_table[_M_index1] % __limit; 365 } 366 367 void 368 _M_initialize(unsigned int __seed) 369 { 370 unsigned int __k = 1; 371 _M_table[54] = __seed; 372 size_t __i; 373 for (__i = 0; __i < 54; __i++) 374 { 375 size_t __ii = (21 * (__i + 1) % 55) - 1; 376 _M_table[__ii] = __k; 377 __k = __seed - __k; 378 __seed = _M_table[__ii]; 379 } 380 for (int __loop = 0; __loop < 4; __loop++) 381 { 382 for (__i = 0; __i < 55; __i++) 383 _M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55]; 384 } 385 _M_index1 = 0; 386 _M_index2 = 31; 387 } 388 389 /// Ctor allowing you to initialize the seed. 390 subtractive_rng(unsigned int __seed) 391 { _M_initialize(__seed); } 392 393 /// Default ctor; initializes its state with some number you don't see. 394 subtractive_rng() 395 { _M_initialize(161803398u); } 396 }; 397 398 // Mem_fun adaptor helper functions mem_fun1 and mem_fun1_ref, 399 // provided for backward compatibility, they are no longer part of 400 // the C++ standard. 401 402 template <class _Ret, class _Tp, class _Arg> 403 inline mem_fun1_t<_Ret, _Tp, _Arg> 404 mem_fun1(_Ret (_Tp::*__f)(_Arg)) 405 { return mem_fun1_t<_Ret, _Tp, _Arg>(__f); } 406 407 template <class _Ret, class _Tp, class _Arg> 408 inline const_mem_fun1_t<_Ret, _Tp, _Arg> 409 mem_fun1(_Ret (_Tp::*__f)(_Arg) const) 410 { return const_mem_fun1_t<_Ret, _Tp, _Arg>(__f); } 411 412 template <class _Ret, class _Tp, class _Arg> 413 inline mem_fun1_ref_t<_Ret, _Tp, _Arg> 414 mem_fun1_ref(_Ret (_Tp::*__f)(_Arg)) 415 { return mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); } 416 417 template <class _Ret, class _Tp, class _Arg> 418 inline const_mem_fun1_ref_t<_Ret, _Tp, _Arg> 419 mem_fun1_ref(_Ret (_Tp::*__f)(_Arg) const) 420 { return const_mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); } 421 422 _GLIBCXX_END_NAMESPACE 423 424 #endif 425 426
