algorithm

Go to the documentation of this file.
00001 // Algorithm extensions -*- C++ -*- 00002 00003 // Copyright (C) 2001, 2002 Free Software Foundation, Inc. 00004 // 00005 // This file is part of the GNU ISO C++ Library. This library is free 00006 // software; you can redistribute it and/or modify it under the 00007 // terms of the GNU General Public License as published by the 00008 // Free Software Foundation; either version 2, or (at your option) 00009 // any later version. 00010 00011 // This library is distributed in the hope that it will be useful, 00012 // but WITHOUT ANY WARRANTY; without even the implied warranty of 00013 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 00014 // GNU General Public License for more details. 00015 00016 // You should have received a copy of the GNU General Public License along 00017 // with this library; see the file COPYING. If not, write to the Free 00018 // Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, 00019 // USA. 00020 00021 // As a special exception, you may use this file as part of a free software 00022 // library without restriction. Specifically, if other files instantiate 00023 // templates or use macros or inline functions from this file, or you compile 00024 // this file and link it with other files to produce an executable, this 00025 // file does not by itself cause the resulting executable to be covered by 00026 // the GNU General Public License. This exception does not however 00027 // invalidate any other reasons why the executable file might be covered by 00028 // the GNU General Public License. 00029 00030 /* 00031 * 00032 * Copyright (c) 1994 00033 * Hewlett-Packard Company 00034 * 00035 * Permission to use, copy, modify, distribute and sell this software 00036 * and its documentation for any purpose is hereby granted without fee, 00037 * provided that the above copyright notice appear in all copies and 00038 * that both that copyright notice and this permission notice appear 00039 * in supporting documentation. Hewlett-Packard Company makes no 00040 * representations about the suitability of this software for any 00041 * purpose. It is provided "as is" without express or implied warranty. 00042 * 00043 * 00044 * Copyright (c) 1996 00045 * Silicon Graphics Computer Systems, Inc. 00046 * 00047 * Permission to use, copy, modify, distribute and sell this software 00048 * and its documentation for any purpose is hereby granted without fee, 00049 * provided that the above copyright notice appear in all copies and 00050 * that both that copyright notice and this permission notice appear 00051 * in supporting documentation. Silicon Graphics makes no 00052 * representations about the suitability of this software for any 00053 * purpose. It is provided "as is" without express or implied warranty. 00054 */ 00055 00056 /** @file ext/algorithm 00057 * This file is a GNU extension to the Standard C++ Library (possibly 00058 * containing extensions from the HP/SGI STL subset). You should only 00059 * include this header if you are using GCC 3 or later. 00060 */ 00061 00062 #ifndef _EXT_ALGORITHM 00063 #define _EXT_ALGORITHM 1 00064 00065 #pragma GCC system_header 00066 00067 #include <algorithm> 00068 00069 namespace __gnu_cxx 00070 { 00071 using std::ptrdiff_t; 00072 using std::min; 00073 using std::pair; 00074 using std::input_iterator_tag; 00075 using std::random_access_iterator_tag; 00076 using std::iterator_traits; 00077 00078 //-------------------------------------------------- 00079 // copy_n (not part of the C++ standard) 00080 00081 template<typename _InputIterator, typename _Size, typename _OutputIterator> 00082 pair<_InputIterator, _OutputIterator> 00083 __copy_n(_InputIterator __first, _Size __count, 00084 _OutputIterator __result, 00085 input_iterator_tag) 00086 { 00087 for ( ; __count > 0; --__count) { 00088 *__result = *__first; 00089 ++__first; 00090 ++__result; 00091 } 00092 return pair<_InputIterator, _OutputIterator>(__first, __result); 00093 } 00094 00095 template<typename _RAIterator, typename _Size, typename _OutputIterator> 00096 inline pair<_RAIterator, _OutputIterator> 00097 __copy_n(_RAIterator __first, _Size __count, 00098 _OutputIterator __result, 00099 random_access_iterator_tag) 00100 { 00101 _RAIterator __last = __first + __count; 00102 return pair<_RAIterator, _OutputIterator>(__last, 00103 std::copy(__first, __last, __result)); 00104 } 00105 00106 /** 00107 * @brief Copies the range [first,first+count) into [result,result+count). 00108 * @param first An input iterator. 00109 * @param count The number of elements to copy. 00110 * @param result An output iterator. 00111 * @return A std::pair composed of first+count and result+count. 00112 * 00113 * This is an SGI extension. 00114 * This inline function will boil down to a call to @c memmove whenever 00115 * possible. Failing that, if random access iterators are passed, then the 00116 * loop count will be known (and therefore a candidate for compiler 00117 * optimizations such as unrolling). 00118 * @ingroup SGIextensions 00119 */ 00120 template<typename _InputIterator, typename _Size, typename _OutputIterator> 00121 inline pair<_InputIterator, _OutputIterator> 00122 copy_n(_InputIterator __first, _Size __count, _OutputIterator __result) 00123 { 00124 // concept requirements 00125 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00126 __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator, 00127 typename iterator_traits<_InputIterator>::value_type>) 00128 00129 return __copy_n(__first, __count, __result, 00130 std::__iterator_category(__first)); 00131 } 00132 00133 template<typename _InputIterator1, typename _InputIterator2> 00134 int 00135 __lexicographical_compare_3way(_InputIterator1 __first1, _InputIterator1 __last1, 00136 _InputIterator2 __first2, _InputIterator2 __last2) 00137 { 00138 while (__first1 != __last1 && __first2 != __last2) { 00139 if (*__first1 < *__first2) 00140 return -1; 00141 if (*__first2 < *__first1) 00142 return 1; 00143 ++__first1; 00144 ++__first2; 00145 } 00146 if (__first2 == __last2) { 00147 return !(__first1 == __last1); 00148 } 00149 else { 00150 return -1; 00151 } 00152 } 00153 00154 inline int 00155 __lexicographical_compare_3way(const unsigned char* __first1, 00156 const unsigned char* __last1, 00157 const unsigned char* __first2, 00158 const unsigned char* __last2) 00159 { 00160 const ptrdiff_t __len1 = __last1 - __first1; 00161 const ptrdiff_t __len2 = __last2 - __first2; 00162 const int __result = std::memcmp(__first1, __first2, min(__len1, __len2)); 00163 return __result != 0 ? __result 00164 : (__len1 == __len2 ? 0 : (__len1 < __len2 ? -1 : 1)); 00165 } 00166 00167 inline int 00168 __lexicographical_compare_3way(const char* __first1, const char* __last1, 00169 const char* __first2, const char* __last2) 00170 { 00171 #if CHAR_MAX == SCHAR_MAX 00172 return __lexicographical_compare_3way( 00173 (const signed char*) __first1, 00174 (const signed char*) __last1, 00175 (const signed char*) __first2, 00176 (const signed char*) __last2); 00177 #else 00178 return __lexicographical_compare_3way((const unsigned char*) __first1, 00179 (const unsigned char*) __last1, 00180 (const unsigned char*) __first2, 00181 (const unsigned char*) __last2); 00182 #endif 00183 } 00184 00185 /** 00186 * @brief @c memcmp on steroids. 00187 * @param first1 An input iterator. 00188 * @param last1 An input iterator. 00189 * @param first2 An input iterator. 00190 * @param last2 An input iterator. 00191 * @return An int, as with @c memcmp. 00192 * 00193 * The return value will be less than zero if the first range is 00194 * "lexigraphically less than" the second, greater than zero if the second 00195 * range is "lexigraphically less than" the first, and zero otherwise. 00196 * This is an SGI extension. 00197 * @ingroup SGIextensions 00198 */ 00199 template<typename _InputIterator1, typename _InputIterator2> 00200 int 00201 lexicographical_compare_3way(_InputIterator1 __first1, _InputIterator1 __last1, 00202 _InputIterator2 __first2, _InputIterator2 __last2) 00203 { 00204 // concept requirements 00205 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>) 00206 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>) 00207 __glibcxx_function_requires(_LessThanComparableConcept< 00208 typename iterator_traits<_InputIterator1>::value_type>) 00209 __glibcxx_function_requires(_LessThanComparableConcept< 00210 typename iterator_traits<_InputIterator2>::value_type>) 00211 __glibcxx_requires_valid_range(__first1, __last1); 00212 __glibcxx_requires_valid_range(__first2, __last2); 00213 00214 return __lexicographical_compare_3way(__first1, __last1, __first2, __last2); 00215 } 00216 00217 // count and count_if: this version, whose return type is void, was present 00218 // in the HP STL, and is retained as an extension for backward compatibility. 00219 00220 template<typename _InputIterator, typename _Tp, typename _Size> 00221 void 00222 count(_InputIterator __first, _InputIterator __last, 00223 const _Tp& __value, 00224 _Size& __n) 00225 { 00226 // concept requirements 00227 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00228 __glibcxx_function_requires(_EqualityComparableConcept< 00229 typename iterator_traits<_InputIterator>::value_type >) 00230 __glibcxx_function_requires(_EqualityComparableConcept<_Tp>) 00231 __glibcxx_requires_valid_range(__first, __last); 00232 00233 for ( ; __first != __last; ++__first) 00234 if (*__first == __value) 00235 ++__n; 00236 } 00237 00238 template<typename _InputIterator, typename _Predicate, typename _Size> 00239 void 00240 count_if(_InputIterator __first, _InputIterator __last, 00241 _Predicate __pred, 00242 _Size& __n) 00243 { 00244 // concept requirements 00245 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00246 __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate, 00247 typename iterator_traits<_InputIterator>::value_type>) 00248 __glibcxx_requires_valid_range(__first, __last); 00249 00250 for ( ; __first != __last; ++__first) 00251 if (__pred(*__first)) 00252 ++__n; 00253 } 00254 00255 // random_sample and random_sample_n (extensions, not part of the standard). 00256 00257 /** 00258 * This is an SGI extension. 00259 * @ingroup SGIextensions 00260 * @doctodo 00261 */ 00262 template<typename _ForwardIterator, typename _OutputIterator, typename _Distance> 00263 _OutputIterator 00264 random_sample_n(_ForwardIterator __first, _ForwardIterator __last, 00265 _OutputIterator __out, const _Distance __n) 00266 { 00267 // concept requirements 00268 __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>) 00269 __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator, 00270 typename iterator_traits<_ForwardIterator>::value_type>) 00271 __glibcxx_requires_valid_range(__first, __last); 00272 00273 _Distance __remaining = std::distance(__first, __last); 00274 _Distance __m = min(__n, __remaining); 00275 00276 while (__m > 0) { 00277 if ((std::rand() % __remaining) < __m) { 00278 *__out = *__first; 00279 ++__out; 00280 --__m; 00281 } 00282 00283 --__remaining; 00284 ++__first; 00285 } 00286 return __out; 00287 } 00288 00289 /** 00290 * This is an SGI extension. 00291 * @ingroup SGIextensions 00292 * @doctodo 00293 */ 00294 template<typename _ForwardIterator, typename _OutputIterator, typename _Distance, 00295 typename _RandomNumberGenerator> 00296 _OutputIterator 00297 random_sample_n(_ForwardIterator __first, _ForwardIterator __last, 00298 _OutputIterator __out, const _Distance __n, 00299 _RandomNumberGenerator& __rand) 00300 { 00301 // concept requirements 00302 __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>) 00303 __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator, 00304 typename iterator_traits<_ForwardIterator>::value_type>) 00305 __glibcxx_function_requires(_UnaryFunctionConcept< 00306 _RandomNumberGenerator, _Distance, _Distance>) 00307 __glibcxx_requires_valid_range(__first, __last); 00308 00309 _Distance __remaining = std::distance(__first, __last); 00310 _Distance __m = min(__n, __remaining); 00311 00312 while (__m > 0) { 00313 if (__rand(__remaining) < __m) { 00314 *__out = *__first; 00315 ++__out; 00316 --__m; 00317 } 00318 00319 --__remaining; 00320 ++__first; 00321 } 00322 return __out; 00323 } 00324 00325 template<typename _InputIterator, typename _RandomAccessIterator, typename _Distance> 00326 _RandomAccessIterator 00327 __random_sample(_InputIterator __first, _InputIterator __last, 00328 _RandomAccessIterator __out, 00329 const _Distance __n) 00330 { 00331 _Distance __m = 0; 00332 _Distance __t = __n; 00333 for ( ; __first != __last && __m < __n; ++__m, ++__first) 00334 __out[__m] = *__first; 00335 00336 while (__first != __last) { 00337 ++__t; 00338 _Distance __M = std::rand() % (__t); 00339 if (__M < __n) 00340 __out[__M] = *__first; 00341 ++__first; 00342 } 00343 00344 return __out + __m; 00345 } 00346 00347 template<typename _InputIterator, typename _RandomAccessIterator, 00348 typename _RandomNumberGenerator, typename _Distance> 00349 _RandomAccessIterator 00350 __random_sample(_InputIterator __first, _InputIterator __last, 00351 _RandomAccessIterator __out, 00352 _RandomNumberGenerator& __rand, 00353 const _Distance __n) 00354 { 00355 // concept requirements 00356 __glibcxx_function_requires(_UnaryFunctionConcept< 00357 _RandomNumberGenerator, _Distance, _Distance>) 00358 00359 _Distance __m = 0; 00360 _Distance __t = __n; 00361 for ( ; __first != __last && __m < __n; ++__m, ++__first) 00362 __out[__m] = *__first; 00363 00364 while (__first != __last) { 00365 ++__t; 00366 _Distance __M = __rand(__t); 00367 if (__M < __n) 00368 __out[__M] = *__first; 00369 ++__first; 00370 } 00371 00372 return __out + __m; 00373 } 00374 00375 /** 00376 * This is an SGI extension. 00377 * @ingroup SGIextensions 00378 * @doctodo 00379 */ 00380 template<typename _InputIterator, typename _RandomAccessIterator> 00381 inline _RandomAccessIterator 00382 random_sample(_InputIterator __first, _InputIterator __last, 00383 _RandomAccessIterator __out_first, _RandomAccessIterator __out_last) 00384 { 00385 // concept requirements 00386 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00387 __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept< 00388 _RandomAccessIterator>) 00389 __glibcxx_requires_valid_range(__first, __last); 00390 __glibcxx_requires_valid_range(__out_first, __out_last); 00391 00392 return __random_sample(__first, __last, 00393 __out_first, __out_last - __out_first); 00394 } 00395 00396 /** 00397 * This is an SGI extension. 00398 * @ingroup SGIextensions 00399 * @doctodo 00400 */ 00401 template<typename _InputIterator, typename _RandomAccessIterator, 00402 typename _RandomNumberGenerator> 00403 inline _RandomAccessIterator 00404 random_sample(_InputIterator __first, _InputIterator __last, 00405 _RandomAccessIterator __out_first, _RandomAccessIterator __out_last, 00406 _RandomNumberGenerator& __rand) 00407 { 00408 // concept requirements 00409 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) 00410 __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept< 00411 _RandomAccessIterator>) 00412 __glibcxx_requires_valid_range(__first, __last); 00413 __glibcxx_requires_valid_range(__out_first, __out_last); 00414 00415 return __random_sample(__first, __last, 00416 __out_first, __rand, 00417 __out_last - __out_first); 00418 } 00419 00420 /** 00421 * This is an SGI extension. 00422 * @ingroup SGIextensions 00423 * @doctodo 00424 */ 00425 template<typename _RandomAccessIterator> 00426 inline bool 00427 is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last) 00428 { 00429 // concept requirements 00430 __glibcxx_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>) 00431 __glibcxx_function_requires(_LessThanComparableConcept< 00432 typename iterator_traits<_RandomAccessIterator>::value_type>) 00433 __glibcxx_requires_valid_range(__first, __last); 00434 00435 return std::__is_heap(__first, __last - __first); 00436 } 00437 00438 /** 00439 * This is an SGI extension. 00440 * @ingroup SGIextensions 00441 * @doctodo 00442 */ 00443 template<typename _RandomAccessIterator, typename _StrictWeakOrdering> 00444 inline bool 00445 is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, 00446 _StrictWeakOrdering __comp) 00447 { 00448 // concept requirements 00449 __glibcxx_function_requires(_RandomAccessIteratorConcept<_RandomAccessIterator>) 00450 __glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering, 00451 typename iterator_traits<_RandomAccessIterator>::value_type, 00452 typename iterator_traits<_RandomAccessIterator>::value_type>) 00453 __glibcxx_requires_valid_range(__first, __last); 00454 00455 return std::__is_heap(__first, __comp, __last - __first); 00456 } 00457 00458 // is_sorted, a predicated testing whether a range is sorted in 00459 // nondescending order. This is an extension, not part of the C++ 00460 // standard. 00461 00462 /** 00463 * This is an SGI extension. 00464 * @ingroup SGIextensions 00465 * @doctodo 00466 */ 00467 template<typename _ForwardIterator> 00468 bool 00469 is_sorted(_ForwardIterator __first, _ForwardIterator __last) 00470 { 00471 // concept requirements 00472 __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>) 00473 __glibcxx_function_requires(_LessThanComparableConcept< 00474 typename iterator_traits<_ForwardIterator>::value_type>) 00475 __glibcxx_requires_valid_range(__first, __last); 00476 00477 if (__first == __last) 00478 return true; 00479 00480 _ForwardIterator __next = __first; 00481 for (++__next; __next != __last; __first = __next, ++__next) { 00482 if (*__next < *__first) 00483 return false; 00484 } 00485 00486 return true; 00487 } 00488 00489 /** 00490 * This is an SGI extension. 00491 * @ingroup SGIextensions 00492 * @doctodo 00493 */ 00494 template<typename _ForwardIterator, typename _StrictWeakOrdering> 00495 bool 00496 is_sorted(_ForwardIterator __first, _ForwardIterator __last, _StrictWeakOrdering __comp) 00497 { 00498 // concept requirements 00499 __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>) 00500 __glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering, 00501 typename iterator_traits<_ForwardIterator>::value_type, 00502 typename iterator_traits<_ForwardIterator>::value_type>) 00503 __glibcxx_requires_valid_range(__first, __last); 00504 00505 if (__first == __last) 00506 return true; 00507 00508 _ForwardIterator __next = __first; 00509 for (++__next; __next != __last; __first = __next, ++__next) { 00510 if (__comp(*__next, *__first)) 00511 return false; 00512 } 00513 00514 return true; 00515 } 00516 } // namespace __gnu_cxx 00517 00518 #endif /* _EXT_ALGORITHM */

Generated on Wed Sep 8 10:19:27 2004 for libstdc++-v3 Source by doxygen 1.3.8