libstdc++
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00001 // Functional extensions -*- C++ -*- 00002 00003 // Copyright (C) 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010 00004 // Free Software Foundation, Inc. 00005 // 00006 // This file is part of the GNU ISO C++ Library. This library is free 00007 // software; you can redistribute it and/or modify it under the 00008 // terms of the GNU General Public License as published by the 00009 // Free Software Foundation; either version 3, or (at your option) 00010 // any later version. 00011 00012 // This library is distributed in the hope that it will be useful, 00013 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00014 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00015 // GNU General Public License for more details. 00016 00017 // Under Section 7 of GPL version 3, you are granted additional 00018 // permissions described in the GCC Runtime Library Exception, version 00019 // 3.1, as published by the Free Software Foundation. 00020 00021 // You should have received a copy of the GNU General Public License and 00022 // a copy of the GCC Runtime Library Exception along with this program; 00023 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see 00024 // <http://www.gnu.org/licenses/>. 00025 00026 /* 00027 * 00028 * Copyright (c) 1994 00029 * Hewlett-Packard Company 00030 * 00031 * Permission to use, copy, modify, distribute and sell this software 00032 * and its documentation for any purpose is hereby granted without fee, 00033 * provided that the above copyright notice appear in all copies and 00034 * that both that copyright notice and this permission notice appear 00035 * in supporting documentation. Hewlett-Packard Company makes no 00036 * representations about the suitability of this software for any 00037 * purpose. It is provided "as is" without express or implied warranty. 00038 * 00039 * 00040 * Copyright (c) 1996 00041 * Silicon Graphics Computer Systems, Inc. 00042 * 00043 * Permission to use, copy, modify, distribute and sell this software 00044 * and its documentation for any purpose is hereby granted without fee, 00045 * provided that the above copyright notice appear in all copies and 00046 * that both that copyright notice and this permission notice appear 00047 * in supporting documentation. Silicon Graphics makes no 00048 * representations about the suitability of this software for any 00049 * purpose. It is provided "as is" without express or implied warranty. 00050 */ 00051 00052 /** @file ext/functional 00053 * This file is a GNU extension to the Standard C++ Library (possibly 00054 * containing extensions from the HP/SGI STL subset). 00055 */ 00056 00057 #ifndef _EXT_FUNCTIONAL 00058 #define _EXT_FUNCTIONAL 1 00059 00060 #pragma GCC system_header 00061 00062 #include <functional> 00063 00064 namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) 00065 { 00066 _GLIBCXX_BEGIN_NAMESPACE_VERSION 00067 00068 using std::size_t; 00069 using std::unary_function; 00070 using std::binary_function; 00071 using std::mem_fun1_t; 00072 using std::const_mem_fun1_t; 00073 using std::mem_fun1_ref_t; 00074 using std::const_mem_fun1_ref_t; 00075 00076 /** The @c identity_element functions are not part of the C++ 00077 * standard; SGI provided them as an extension. Its argument is an 00078 * operation, and its return value is the identity element for that 00079 * operation. It is overloaded for addition and multiplication, 00080 * and you can overload it for your own nefarious operations. 00081 * 00082 * @addtogroup SGIextensions 00083 * @{ 00084 */ 00085 /// An \link SGIextensions SGI extension \endlink. 00086 template <class _Tp> 00087 inline _Tp 00088 identity_element(std::plus<_Tp>) 00089 { return _Tp(0); } 00090 00091 /// An \link SGIextensions SGI extension \endlink. 00092 template <class _Tp> 00093 inline _Tp 00094 identity_element(std::multiplies<_Tp>) 00095 { return _Tp(1); } 00096 /** @} */ 00097 00098 /** As an extension to the binders, SGI provided composition functors and 00099 * wrapper functions to aid in their creation. The @c unary_compose 00100 * functor is constructed from two functions/functors, @c f and @c g. 00101 * Calling @c operator() with a single argument @c x returns @c f(g(x)). 00102 * The function @c compose1 takes the two functions and constructs a 00103 * @c unary_compose variable for you. 00104 * 00105 * @c binary_compose is constructed from three functors, @c f, @c g1, 00106 * and @c g2. Its @c operator() returns @c f(g1(x),g2(x)). The function 00107 * compose2 takes f, g1, and g2, and constructs the @c binary_compose 00108 * instance for you. For example, if @c f returns an int, then 00109 * \code 00110 * int answer = (compose2(f,g1,g2))(x); 00111 * \endcode 00112 * is equivalent to 00113 * \code 00114 * int temp1 = g1(x); 00115 * int temp2 = g2(x); 00116 * int answer = f(temp1,temp2); 00117 * \endcode 00118 * But the first form is more compact, and can be passed around as a 00119 * functor to other algorithms. 00120 * 00121 * @addtogroup SGIextensions 00122 * @{ 00123 */ 00124 /// An \link SGIextensions SGI extension \endlink. 00125 template <class _Operation1, class _Operation2> 00126 class unary_compose 00127 : public unary_function<typename _Operation2::argument_type, 00128 typename _Operation1::result_type> 00129 { 00130 protected: 00131 _Operation1 _M_fn1; 00132 _Operation2 _M_fn2; 00133 00134 public: 00135 unary_compose(const _Operation1& __x, const _Operation2& __y) 00136 : _M_fn1(__x), _M_fn2(__y) {} 00137 00138 typename _Operation1::result_type 00139 operator()(const typename _Operation2::argument_type& __x) const 00140 { return _M_fn1(_M_fn2(__x)); } 00141 }; 00142 00143 /// An \link SGIextensions SGI extension \endlink. 00144 template <class _Operation1, class _Operation2> 00145 inline unary_compose<_Operation1, _Operation2> 00146 compose1(const _Operation1& __fn1, const _Operation2& __fn2) 00147 { return unary_compose<_Operation1,_Operation2>(__fn1, __fn2); } 00148 00149 /// An \link SGIextensions SGI extension \endlink. 00150 template <class _Operation1, class _Operation2, class _Operation3> 00151 class binary_compose 00152 : public unary_function<typename _Operation2::argument_type, 00153 typename _Operation1::result_type> 00154 { 00155 protected: 00156 _Operation1 _M_fn1; 00157 _Operation2 _M_fn2; 00158 _Operation3 _M_fn3; 00159 00160 public: 00161 binary_compose(const _Operation1& __x, const _Operation2& __y, 00162 const _Operation3& __z) 00163 : _M_fn1(__x), _M_fn2(__y), _M_fn3(__z) { } 00164 00165 typename _Operation1::result_type 00166 operator()(const typename _Operation2::argument_type& __x) const 00167 { return _M_fn1(_M_fn2(__x), _M_fn3(__x)); } 00168 }; 00169 00170 /// An \link SGIextensions SGI extension \endlink. 00171 template <class _Operation1, class _Operation2, class _Operation3> 00172 inline binary_compose<_Operation1, _Operation2, _Operation3> 00173 compose2(const _Operation1& __fn1, const _Operation2& __fn2, 00174 const _Operation3& __fn3) 00175 { return binary_compose<_Operation1, _Operation2, _Operation3> 00176 (__fn1, __fn2, __fn3); } 00177 /** @} */ 00178 00179 /** As an extension, SGI provided a functor called @c identity. When a 00180 * functor is required but no operations are desired, this can be used as a 00181 * pass-through. Its @c operator() returns its argument unchanged. 00182 * 00183 * @addtogroup SGIextensions 00184 */ 00185 template <class _Tp> 00186 struct identity : public std::_Identity<_Tp> {}; 00187 00188 /** @c select1st and @c select2nd are extensions provided by SGI. Their 00189 * @c operator()s 00190 * take a @c std::pair as an argument, and return either the first member 00191 * or the second member, respectively. They can be used (especially with 00192 * the composition functors) to @a strip data from a sequence before 00193 * performing the remainder of an algorithm. 00194 * 00195 * @addtogroup SGIextensions 00196 * @{ 00197 */ 00198 /// An \link SGIextensions SGI extension \endlink. 00199 template <class _Pair> 00200 struct select1st : public std::_Select1st<_Pair> {}; 00201 00202 /// An \link SGIextensions SGI extension \endlink. 00203 template <class _Pair> 00204 struct select2nd : public std::_Select2nd<_Pair> {}; 00205 /** @} */ 00206 00207 // extension documented next 00208 template <class _Arg1, class _Arg2> 00209 struct _Project1st : public binary_function<_Arg1, _Arg2, _Arg1> 00210 { 00211 _Arg1 00212 operator()(const _Arg1& __x, const _Arg2&) const 00213 { return __x; } 00214 }; 00215 00216 template <class _Arg1, class _Arg2> 00217 struct _Project2nd : public binary_function<_Arg1, _Arg2, _Arg2> 00218 { 00219 _Arg2 00220 operator()(const _Arg1&, const _Arg2& __y) const 00221 { return __y; } 00222 }; 00223 00224 /** The @c operator() of the @c project1st functor takes two arbitrary 00225 * arguments and returns the first one, while @c project2nd returns the 00226 * second one. They are extensions provided by SGI. 00227 * 00228 * @addtogroup SGIextensions 00229 * @{ 00230 */ 00231 00232 /// An \link SGIextensions SGI extension \endlink. 00233 template <class _Arg1, class _Arg2> 00234 struct project1st : public _Project1st<_Arg1, _Arg2> {}; 00235 00236 /// An \link SGIextensions SGI extension \endlink. 00237 template <class _Arg1, class _Arg2> 00238 struct project2nd : public _Project2nd<_Arg1, _Arg2> {}; 00239 /** @} */ 00240 00241 // extension documented next 00242 template <class _Result> 00243 struct _Constant_void_fun 00244 { 00245 typedef _Result result_type; 00246 result_type _M_val; 00247 00248 _Constant_void_fun(const result_type& __v) : _M_val(__v) {} 00249 00250 const result_type& 00251 operator()() const 00252 { return _M_val; } 00253 }; 00254 00255 template <class _Result, class _Argument> 00256 struct _Constant_unary_fun 00257 { 00258 typedef _Argument argument_type; 00259 typedef _Result result_type; 00260 result_type _M_val; 00261 00262 _Constant_unary_fun(const result_type& __v) : _M_val(__v) {} 00263 00264 const result_type& 00265 operator()(const _Argument&) const 00266 { return _M_val; } 00267 }; 00268 00269 template <class _Result, class _Arg1, class _Arg2> 00270 struct _Constant_binary_fun 00271 { 00272 typedef _Arg1 first_argument_type; 00273 typedef _Arg2 second_argument_type; 00274 typedef _Result result_type; 00275 _Result _M_val; 00276 00277 _Constant_binary_fun(const _Result& __v) : _M_val(__v) {} 00278 00279 const result_type& 00280 operator()(const _Arg1&, const _Arg2&) const 00281 { return _M_val; } 00282 }; 00283 00284 /** These three functors are each constructed from a single arbitrary 00285 * variable/value. Later, their @c operator()s completely ignore any 00286 * arguments passed, and return the stored value. 00287 * - @c constant_void_fun's @c operator() takes no arguments 00288 * - @c constant_unary_fun's @c operator() takes one argument (ignored) 00289 * - @c constant_binary_fun's @c operator() takes two arguments (ignored) 00290 * 00291 * The helper creator functions @c constant0, @c constant1, and 00292 * @c constant2 each take a @a result argument and construct variables of 00293 * the appropriate functor type. 00294 * 00295 * @addtogroup SGIextensions 00296 * @{ 00297 */ 00298 /// An \link SGIextensions SGI extension \endlink. 00299 template <class _Result> 00300 struct constant_void_fun 00301 : public _Constant_void_fun<_Result> 00302 { 00303 constant_void_fun(const _Result& __v) 00304 : _Constant_void_fun<_Result>(__v) {} 00305 }; 00306 00307 /// An \link SGIextensions SGI extension \endlink. 00308 template <class _Result, class _Argument = _Result> 00309 struct constant_unary_fun : public _Constant_unary_fun<_Result, _Argument> 00310 { 00311 constant_unary_fun(const _Result& __v) 00312 : _Constant_unary_fun<_Result, _Argument>(__v) {} 00313 }; 00314 00315 /// An \link SGIextensions SGI extension \endlink. 00316 template <class _Result, class _Arg1 = _Result, class _Arg2 = _Arg1> 00317 struct constant_binary_fun 00318 : public _Constant_binary_fun<_Result, _Arg1, _Arg2> 00319 { 00320 constant_binary_fun(const _Result& __v) 00321 : _Constant_binary_fun<_Result, _Arg1, _Arg2>(__v) {} 00322 }; 00323 00324 /// An \link SGIextensions SGI extension \endlink. 00325 template <class _Result> 00326 inline constant_void_fun<_Result> 00327 constant0(const _Result& __val) 00328 { return constant_void_fun<_Result>(__val); } 00329 00330 /// An \link SGIextensions SGI extension \endlink. 00331 template <class _Result> 00332 inline constant_unary_fun<_Result, _Result> 00333 constant1(const _Result& __val) 00334 { return constant_unary_fun<_Result, _Result>(__val); } 00335 00336 /// An \link SGIextensions SGI extension \endlink. 00337 template <class _Result> 00338 inline constant_binary_fun<_Result,_Result,_Result> 00339 constant2(const _Result& __val) 00340 { return constant_binary_fun<_Result, _Result, _Result>(__val); } 00341 /** @} */ 00342 00343 /** The @c subtractive_rng class is documented on 00344 * <a href="http://www.sgi.com/tech/stl/">SGI's site</a>. 00345 * Note that this code assumes that @c int is 32 bits. 00346 * 00347 * @ingroup SGIextensions 00348 */ 00349 class subtractive_rng 00350 : public unary_function<unsigned int, unsigned int> 00351 { 00352 private: 00353 unsigned int _M_table[55]; 00354 size_t _M_index1; 00355 size_t _M_index2; 00356 00357 public: 00358 /// Returns a number less than the argument. 00359 unsigned int 00360 operator()(unsigned int __limit) 00361 { 00362 _M_index1 = (_M_index1 + 1) % 55; 00363 _M_index2 = (_M_index2 + 1) % 55; 00364 _M_table[_M_index1] = _M_table[_M_index1] - _M_table[_M_index2]; 00365 return _M_table[_M_index1] % __limit; 00366 } 00367 00368 void 00369 _M_initialize(unsigned int __seed) 00370 { 00371 unsigned int __k = 1; 00372 _M_table[54] = __seed; 00373 size_t __i; 00374 for (__i = 0; __i < 54; __i++) 00375 { 00376 size_t __ii = (21 * (__i + 1) % 55) - 1; 00377 _M_table[__ii] = __k; 00378 __k = __seed - __k; 00379 __seed = _M_table[__ii]; 00380 } 00381 for (int __loop = 0; __loop < 4; __loop++) 00382 { 00383 for (__i = 0; __i < 55; __i++) 00384 _M_table[__i] = _M_table[__i] - _M_table[(1 + __i + 30) % 55]; 00385 } 00386 _M_index1 = 0; 00387 _M_index2 = 31; 00388 } 00389 00390 /// Ctor allowing you to initialize the seed. 00391 subtractive_rng(unsigned int __seed) 00392 { _M_initialize(__seed); } 00393 00394 /// Default ctor; initializes its state with some number you don't see. 00395 subtractive_rng() 00396 { _M_initialize(161803398u); } 00397 }; 00398 00399 // Mem_fun adaptor helper functions mem_fun1 and mem_fun1_ref, 00400 // provided for backward compatibility, they are no longer part of 00401 // the C++ standard. 00402 00403 template <class _Ret, class _Tp, class _Arg> 00404 inline mem_fun1_t<_Ret, _Tp, _Arg> 00405 mem_fun1(_Ret (_Tp::*__f)(_Arg)) 00406 { return mem_fun1_t<_Ret, _Tp, _Arg>(__f); } 00407 00408 template <class _Ret, class _Tp, class _Arg> 00409 inline const_mem_fun1_t<_Ret, _Tp, _Arg> 00410 mem_fun1(_Ret (_Tp::*__f)(_Arg) const) 00411 { return const_mem_fun1_t<_Ret, _Tp, _Arg>(__f); } 00412 00413 template <class _Ret, class _Tp, class _Arg> 00414 inline mem_fun1_ref_t<_Ret, _Tp, _Arg> 00415 mem_fun1_ref(_Ret (_Tp::*__f)(_Arg)) 00416 { return mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); } 00417 00418 template <class _Ret, class _Tp, class _Arg> 00419 inline const_mem_fun1_ref_t<_Ret, _Tp, _Arg> 00420 mem_fun1_ref(_Ret (_Tp::*__f)(_Arg) const) 00421 { return const_mem_fun1_ref_t<_Ret, _Tp, _Arg>(__f); } 00422 00423 _GLIBCXX_END_NAMESPACE_VERSION 00424 } // namespace 00425 00426 #endif 00427