| 1 |
// Algorithm extensions -*- C++ -*- |
| 2 |
|
| 3 |
// Copyright (C) 2001-2021 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 3, 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 |
// Under Section 7 of GPL version 3, you are granted additional |
| 17 |
// permissions described in the GCC Runtime Library Exception, version |
| 18 |
// 3.1, as published by the Free Software Foundation. |
| 19 |
|
| 20 |
// You should have received a copy of the GNU General Public License and |
| 21 |
// a copy of the GCC Runtime Library Exception along with this program; |
| 22 |
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see |
| 23 |
// <http://www.gnu.org/licenses/>. |
| 24 |
|
| 25 |
/* |
| 26 |
* |
| 27 |
* Copyright (c) 1994 |
| 28 |
* Hewlett-Packard Company |
| 29 |
* |
| 30 |
* Permission to use, copy, modify, distribute and sell this software |
| 31 |
* and its documentation for any purpose is hereby granted without fee, |
| 32 |
* provided that the above copyright notice appear in all copies and |
| 33 |
* that both that copyright notice and this permission notice appear |
| 34 |
* in supporting documentation. Hewlett-Packard Company makes no |
| 35 |
* representations about the suitability of this software for any |
| 36 |
* purpose. It is provided "as is" without express or implied warranty. |
| 37 |
* |
| 38 |
* |
| 39 |
* Copyright (c) 1996 |
| 40 |
* Silicon Graphics Computer Systems, Inc. |
| 41 |
* |
| 42 |
* Permission to use, copy, modify, distribute and sell this software |
| 43 |
* and its documentation for any purpose is hereby granted without fee, |
| 44 |
* provided that the above copyright notice appear in all copies and |
| 45 |
* that both that copyright notice and this permission notice appear |
| 46 |
* in supporting documentation. Silicon Graphics makes no |
| 47 |
* representations about the suitability of this software for any |
| 48 |
* purpose. It is provided "as is" without express or implied warranty. |
| 49 |
*/ |
| 50 |
|
| 51 |
/** @file ext/algorithm |
| 52 |
* This file is a GNU extension to the Standard C++ Library (possibly |
| 53 |
* containing extensions from the HP/SGI STL subset). |
| 54 |
*/ |
| 55 |
|
| 56 |
#ifndef _EXT_ALGORITHM |
| 57 |
#define _EXT_ALGORITHM 1 |
| 58 |
|
| 59 |
#pragma GCC system_header |
| 60 |
|
| 61 |
#include <algorithm> |
| 62 |
|
| 63 |
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) |
| 64 |
{ |
| 65 |
_GLIBCXX_BEGIN_NAMESPACE_VERSION |
| 66 |
|
| 67 |
//-------------------------------------------------- |
| 68 |
// copy_n (not part of the C++ standard) |
| 69 |
|
| 70 |
template<typename _InputIterator, typename _Size, typename _OutputIterator> |
| 71 |
std::pair<_InputIterator, _OutputIterator> |
| 72 |
__copy_n(_InputIterator __first, _Size __count, |
| 73 |
_OutputIterator __result, |
| 74 |
std::input_iterator_tag) |
| 75 |
{ |
| 76 |
for ( ; __count > 0; --__count) |
| 77 |
{ |
| 78 |
*__result = *__first; |
| 79 |
++__first; |
| 80 |
++__result; |
| 81 |
} |
| 82 |
return std::pair<_InputIterator, _OutputIterator>(__first, __result); |
| 83 |
} |
| 84 |
|
| 85 |
template<typename _RAIterator, typename _Size, typename _OutputIterator> |
| 86 |
inline std::pair<_RAIterator, _OutputIterator> |
| 87 |
__copy_n(_RAIterator __first, _Size __count, |
| 88 |
_OutputIterator __result, |
| 89 |
std::random_access_iterator_tag) |
| 90 |
{ |
| 91 |
_RAIterator __last = __first + __count; |
| 92 |
return std::pair<_RAIterator, _OutputIterator>(__last, std::copy(__first, |
| 93 |
__last, |
| 94 |
__result)); |
| 95 |
} |
| 96 |
|
| 97 |
/** |
| 98 |
* @brief Copies the range [first,first+count) into [result,result+count). |
| 99 |
* @param __first An input iterator. |
| 100 |
* @param __count The number of elements to copy. |
| 101 |
* @param __result An output iterator. |
| 102 |
* @return A std::pair composed of first+count and result+count. |
| 103 |
* |
| 104 |
* This is an SGI extension. |
| 105 |
* This inline function will boil down to a call to @c memmove whenever |
| 106 |
* possible. Failing that, if random access iterators are passed, then the |
| 107 |
* loop count will be known (and therefore a candidate for compiler |
| 108 |
* optimizations such as unrolling). |
| 109 |
* @ingroup SGIextensions |
| 110 |
*/ |
| 111 |
template<typename _InputIterator, typename _Size, typename _OutputIterator> |
| 112 |
inline std::pair<_InputIterator, _OutputIterator> |
| 113 |
copy_n(_InputIterator __first, _Size __count, _OutputIterator __result) |
| 114 |
{ |
| 115 |
// concept requirements |
| 116 |
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) |
| 117 |
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator, |
| 118 |
typename std::iterator_traits<_InputIterator>::value_type>) |
| 119 |
|
| 120 |
return __gnu_cxx::__copy_n(__first, __count, __result, |
| 121 |
std::__iterator_category(__first)); |
| 122 |
} |
| 123 |
|
| 124 |
template<typename _InputIterator1, typename _InputIterator2> |
| 125 |
int |
| 126 |
__lexicographical_compare_3way(_InputIterator1 __first1, |
| 127 |
_InputIterator1 __last1, |
| 128 |
_InputIterator2 __first2, |
| 129 |
_InputIterator2 __last2) |
| 130 |
{ |
| 131 |
while (__first1 != __last1 && __first2 != __last2) |
| 132 |
{ |
| 133 |
if (*__first1 < *__first2) |
| 134 |
return -1; |
| 135 |
if (*__first2 < *__first1) |
| 136 |
return 1; |
| 137 |
++__first1; |
| 138 |
++__first2; |
| 139 |
} |
| 140 |
if (__first2 == __last2) |
| 141 |
return !(__first1 == __last1); |
| 142 |
else |
| 143 |
return -1; |
| 144 |
} |
| 145 |
|
| 146 |
inline int |
| 147 |
__lexicographical_compare_3way(const unsigned char* __first1, |
| 148 |
const unsigned char* __last1, |
| 149 |
const unsigned char* __first2, |
| 150 |
const unsigned char* __last2) |
| 151 |
{ |
| 152 |
const std::ptrdiff_t __len1 = __last1 - __first1; |
| 153 |
const std::ptrdiff_t __len2 = __last2 - __first2; |
| 154 |
const int __result = __builtin_memcmp(__first1, __first2, |
| 155 |
(std::min)(__len1, __len2)); |
| 156 |
return __result != 0 ? __result |
| 157 |
: (__len1 == __len2 ? 0 : (__len1 < __len2 ? -1 : 1)); |
| 158 |
} |
| 159 |
|
| 160 |
inline int |
| 161 |
__lexicographical_compare_3way(const char* __first1, const char* __last1, |
| 162 |
const char* __first2, const char* __last2) |
| 163 |
{ |
| 164 |
#if CHAR_MAX == SCHAR_MAX |
| 165 |
return __lexicographical_compare_3way((const signed char*) __first1, |
| 166 |
(const signed char*) __last1, |
| 167 |
(const signed char*) __first2, |
| 168 |
(const signed char*) __last2); |
| 169 |
#else |
| 170 |
return __lexicographical_compare_3way((const unsigned char*) __first1, |
| 171 |
(const unsigned char*) __last1, |
| 172 |
(const unsigned char*) __first2, |
| 173 |
(const unsigned char*) __last2); |
| 174 |
#endif |
| 175 |
} |
| 176 |
|
| 177 |
/** |
| 178 |
* @brief @c memcmp on steroids. |
| 179 |
* @param __first1 An input iterator. |
| 180 |
* @param __last1 An input iterator. |
| 181 |
* @param __first2 An input iterator. |
| 182 |
* @param __last2 An input iterator. |
| 183 |
* @return An int, as with @c memcmp. |
| 184 |
* |
| 185 |
* The return value will be less than zero if the first range is |
| 186 |
* <em>lexigraphically less than</em> the second, greater than zero |
| 187 |
* if the second range is <em>lexigraphically less than</em> the |
| 188 |
* first, and zero otherwise. |
| 189 |
* This is an SGI extension. |
| 190 |
* @ingroup SGIextensions |
| 191 |
*/ |
| 192 |
template<typename _InputIterator1, typename _InputIterator2> |
| 193 |
int |
| 194 |
lexicographical_compare_3way(_InputIterator1 __first1, |
| 195 |
_InputIterator1 __last1, |
| 196 |
_InputIterator2 __first2, |
| 197 |
_InputIterator2 __last2) |
| 198 |
{ |
| 199 |
// concept requirements |
| 200 |
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>) |
| 201 |
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>) |
| 202 |
__glibcxx_function_requires(_LessThanComparableConcept< |
| 203 |
typename std::iterator_traits<_InputIterator1>::value_type>) |
| 204 |
__glibcxx_function_requires(_LessThanComparableConcept< |
| 205 |
typename std::iterator_traits<_InputIterator2>::value_type>) |
| 206 |
__glibcxx_requires_valid_range(__first1, __last1); |
| 207 |
__glibcxx_requires_valid_range(__first2, __last2); |
| 208 |
|
| 209 |
return __lexicographical_compare_3way(__first1, __last1, __first2, |
| 210 |
__last2); |
| 211 |
} |
| 212 |
|
| 213 |
// count and count_if: this version, whose return type is void, was present |
| 214 |
// in the HP STL, and is retained as an extension for backward compatibility. |
| 215 |
template<typename _InputIterator, typename _Tp, typename _Size> |
| 216 |
void |
| 217 |
count(_InputIterator __first, _InputIterator __last, |
| 218 |
const _Tp& __value, |
| 219 |
_Size& __n) |
| 220 |
{ |
| 221 |
// concept requirements |
| 222 |
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) |
| 223 |
__glibcxx_function_requires(_EqualityComparableConcept< |
| 224 |
typename std::iterator_traits<_InputIterator>::value_type >) |
| 225 |
__glibcxx_function_requires(_EqualityComparableConcept<_Tp>) |
| 226 |
__glibcxx_requires_valid_range(__first, __last); |
| 227 |
|
| 228 |
for ( ; __first != __last; ++__first) |
| 229 |
if (*__first == __value) |
| 230 |
++__n; |
| 231 |
} |
| 232 |
|
| 233 |
template<typename _InputIterator, typename _Predicate, typename _Size> |
| 234 |
void |
| 235 |
count_if(_InputIterator __first, _InputIterator __last, |
| 236 |
_Predicate __pred, |
| 237 |
_Size& __n) |
| 238 |
{ |
| 239 |
// concept requirements |
| 240 |
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) |
| 241 |
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate, |
| 242 |
typename std::iterator_traits<_InputIterator>::value_type>) |
| 243 |
__glibcxx_requires_valid_range(__first, __last); |
| 244 |
|
| 245 |
for ( ; __first != __last; ++__first) |
| 246 |
if (__pred(*__first)) |
| 247 |
++__n; |
| 248 |
} |
| 249 |
|
| 250 |
// random_sample and random_sample_n (extensions, not part of the standard). |
| 251 |
|
| 252 |
/** |
| 253 |
* This is an SGI extension. |
| 254 |
* @ingroup SGIextensions |
| 255 |
* @doctodo |
| 256 |
*/ |
| 257 |
template<typename _ForwardIterator, typename _OutputIterator, |
| 258 |
typename _Distance> |
| 259 |
_OutputIterator |
| 260 |
random_sample_n(_ForwardIterator __first, _ForwardIterator __last, |
| 261 |
_OutputIterator __out, const _Distance __n) |
| 262 |
{ |
| 263 |
// concept requirements |
| 264 |
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>) |
| 265 |
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator, |
| 266 |
typename std::iterator_traits<_ForwardIterator>::value_type>) |
| 267 |
__glibcxx_requires_valid_range(__first, __last); |
| 268 |
|
| 269 |
_Distance __remaining = std::distance(__first, __last); |
| 270 |
_Distance __m = (std::min)(__n, __remaining); |
| 271 |
|
| 272 |
while (__m > 0) |
| 273 |
{ |
| 274 |
if ((std::rand() % __remaining) < __m) |
| 275 |
{ |
| 276 |
*__out = *__first; |
| 277 |
++__out; |
| 278 |
--__m; |
| 279 |
} |
| 280 |
--__remaining; |
| 281 |
++__first; |
| 282 |
} |
| 283 |
return __out; |
| 284 |
} |
| 285 |
|
| 286 |
/** |
| 287 |
* This is an SGI extension. |
| 288 |
* @ingroup SGIextensions |
| 289 |
* @doctodo |
| 290 |
*/ |
| 291 |
template<typename _ForwardIterator, typename _OutputIterator, |
| 292 |
typename _Distance, typename _RandomNumberGenerator> |
| 293 |
_OutputIterator |
| 294 |
random_sample_n(_ForwardIterator __first, _ForwardIterator __last, |
| 295 |
_OutputIterator __out, const _Distance __n, |
| 296 |
_RandomNumberGenerator& __rand) |
| 297 |
{ |
| 298 |
// concept requirements |
| 299 |
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>) |
| 300 |
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator, |
| 301 |
typename std::iterator_traits<_ForwardIterator>::value_type>) |
| 302 |
__glibcxx_function_requires(_UnaryFunctionConcept< |
| 303 |
_RandomNumberGenerator, _Distance, _Distance>) |
| 304 |
__glibcxx_requires_valid_range(__first, __last); |
| 305 |
|
| 306 |
_Distance __remaining = std::distance(__first, __last); |
| 307 |
_Distance __m = (std::min)(__n, __remaining); |
| 308 |
|
| 309 |
while (__m > 0) |
| 310 |
{ |
| 311 |
if (__rand(__remaining) < __m) |
| 312 |
{ |
| 313 |
*__out = *__first; |
| 314 |
++__out; |
| 315 |
--__m; |
| 316 |
} |
| 317 |
--__remaining; |
| 318 |
++__first; |
| 319 |
} |
| 320 |
return __out; |
| 321 |
} |
| 322 |
|
| 323 |
template<typename _InputIterator, typename _RandomAccessIterator, |
| 324 |
typename _Distance> |
| 325 |
_RandomAccessIterator |
| 326 |
__random_sample(_InputIterator __first, _InputIterator __last, |
| 327 |
_RandomAccessIterator __out, |
| 328 |
const _Distance __n) |
| 329 |
{ |
| 330 |
_Distance __m = 0; |
| 331 |
_Distance __t = __n; |
| 332 |
for ( ; __first != __last && __m < __n; ++__m, ++__first) |
| 333 |
__out[__m] = *__first; |
| 334 |
|
| 335 |
while (__first != __last) |
| 336 |
{ |
| 337 |
++__t; |
| 338 |
_Distance __M = std::rand() % (__t); |
| 339 |
if (__M < __n) |
| 340 |
__out[__M] = *__first; |
| 341 |
++__first; |
| 342 |
} |
| 343 |
return __out + __m; |
| 344 |
} |
| 345 |
|
| 346 |
template<typename _InputIterator, typename _RandomAccessIterator, |
| 347 |
typename _RandomNumberGenerator, typename _Distance> |
| 348 |
_RandomAccessIterator |
| 349 |
__random_sample(_InputIterator __first, _InputIterator __last, |
| 350 |
_RandomAccessIterator __out, |
| 351 |
_RandomNumberGenerator& __rand, |
| 352 |
const _Distance __n) |
| 353 |
{ |
| 354 |
// concept requirements |
| 355 |
__glibcxx_function_requires(_UnaryFunctionConcept< |
| 356 |
_RandomNumberGenerator, _Distance, _Distance>) |
| 357 |
|
| 358 |
_Distance __m = 0; |
| 359 |
_Distance __t = __n; |
| 360 |
for ( ; __first != __last && __m < __n; ++__m, ++__first) |
| 361 |
__out[__m] = *__first; |
| 362 |
|
| 363 |
while (__first != __last) |
| 364 |
{ |
| 365 |
++__t; |
| 366 |
_Distance __M = __rand(__t); |
| 367 |
if (__M < __n) |
| 368 |
__out[__M] = *__first; |
| 369 |
++__first; |
| 370 |
} |
| 371 |
return __out + __m; |
| 372 |
} |
| 373 |
|
| 374 |
/** |
| 375 |
* This is an SGI extension. |
| 376 |
* @ingroup SGIextensions |
| 377 |
* @doctodo |
| 378 |
*/ |
| 379 |
template<typename _InputIterator, typename _RandomAccessIterator> |
| 380 |
inline _RandomAccessIterator |
| 381 |
random_sample(_InputIterator __first, _InputIterator __last, |
| 382 |
_RandomAccessIterator __out_first, |
| 383 |
_RandomAccessIterator __out_last) |
| 384 |
{ |
| 385 |
// concept requirements |
| 386 |
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) |
| 387 |
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept< |
| 388 |
_RandomAccessIterator>) |
| 389 |
__glibcxx_requires_valid_range(__first, __last); |
| 390 |
__glibcxx_requires_valid_range(__out_first, __out_last); |
| 391 |
|
| 392 |
return __random_sample(__first, __last, |
| 393 |
__out_first, __out_last - __out_first); |
| 394 |
} |
| 395 |
|
| 396 |
/** |
| 397 |
* This is an SGI extension. |
| 398 |
* @ingroup SGIextensions |
| 399 |
* @doctodo |
| 400 |
*/ |
| 401 |
template<typename _InputIterator, typename _RandomAccessIterator, |
| 402 |
typename _RandomNumberGenerator> |
| 403 |
inline _RandomAccessIterator |
| 404 |
random_sample(_InputIterator __first, _InputIterator __last, |
| 405 |
_RandomAccessIterator __out_first, |
| 406 |
_RandomAccessIterator __out_last, |
| 407 |
_RandomNumberGenerator& __rand) |
| 408 |
{ |
| 409 |
// concept requirements |
| 410 |
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>) |
| 411 |
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept< |
| 412 |
_RandomAccessIterator>) |
| 413 |
__glibcxx_requires_valid_range(__first, __last); |
| 414 |
__glibcxx_requires_valid_range(__out_first, __out_last); |
| 415 |
|
| 416 |
return __random_sample(__first, __last, |
| 417 |
__out_first, __rand, |
| 418 |
__out_last - __out_first); |
| 419 |
} |
| 420 |
|
| 421 |
#if __cplusplus >= 201103L |
| 422 |
using std::is_heap; |
| 423 |
#else |
| 424 |
/** |
| 425 |
* This is an SGI extension. |
| 426 |
* @ingroup SGIextensions |
| 427 |
* @doctodo |
| 428 |
*/ |
| 429 |
template<typename _RandomAccessIterator> |
| 430 |
inline bool |
| 431 |
is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last) |
| 432 |
{ |
| 433 |
// concept requirements |
| 434 |
__glibcxx_function_requires(_RandomAccessIteratorConcept< |
| 435 |
_RandomAccessIterator>) |
| 436 |
__glibcxx_function_requires(_LessThanComparableConcept< |
| 437 |
typename std::iterator_traits<_RandomAccessIterator>::value_type>) |
| 438 |
__glibcxx_requires_valid_range(__first, __last); |
| 439 |
|
| 440 |
return std::__is_heap(__first, __last - __first); |
| 441 |
} |
| 442 |
|
| 443 |
/** |
| 444 |
* This is an SGI extension. |
| 445 |
* @ingroup SGIextensions |
| 446 |
* @doctodo |
| 447 |
*/ |
| 448 |
template<typename _RandomAccessIterator, typename _StrictWeakOrdering> |
| 449 |
inline bool |
| 450 |
is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last, |
| 451 |
_StrictWeakOrdering __comp) |
| 452 |
{ |
| 453 |
// concept requirements |
| 454 |
__glibcxx_function_requires(_RandomAccessIteratorConcept< |
| 455 |
_RandomAccessIterator>) |
| 456 |
__glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering, |
| 457 |
typename std::iterator_traits<_RandomAccessIterator>::value_type, |
| 458 |
typename std::iterator_traits<_RandomAccessIterator>::value_type>) |
| 459 |
__glibcxx_requires_valid_range(__first, __last); |
| 460 |
|
| 461 |
return std::__is_heap(__first, __comp, __last - __first); |
| 462 |
} |
| 463 |
#endif |
| 464 |
|
| 465 |
#if __cplusplus >= 201103L |
| 466 |
using std::is_sorted; |
| 467 |
#else |
| 468 |
// is_sorted, a predicated testing whether a range is sorted in |
| 469 |
// nondescending order. This is an extension, not part of the C++ |
| 470 |
// standard. |
| 471 |
|
| 472 |
/** |
| 473 |
* This is an SGI extension. |
| 474 |
* @ingroup SGIextensions |
| 475 |
* @doctodo |
| 476 |
*/ |
| 477 |
template<typename _ForwardIterator> |
| 478 |
bool |
| 479 |
is_sorted(_ForwardIterator __first, _ForwardIterator __last) |
| 480 |
{ |
| 481 |
// concept requirements |
| 482 |
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>) |
| 483 |
__glibcxx_function_requires(_LessThanComparableConcept< |
| 484 |
typename std::iterator_traits<_ForwardIterator>::value_type>) |
| 485 |
__glibcxx_requires_valid_range(__first, __last); |
| 486 |
|
| 487 |
if (__first == __last) |
| 488 |
return true; |
| 489 |
|
| 490 |
_ForwardIterator __next = __first; |
| 491 |
for (++__next; __next != __last; __first = __next, ++__next) |
| 492 |
if (*__next < *__first) |
| 493 |
return false; |
| 494 |
return true; |
| 495 |
} |
| 496 |
|
| 497 |
/** |
| 498 |
* This is an SGI extension. |
| 499 |
* @ingroup SGIextensions |
| 500 |
* @doctodo |
| 501 |
*/ |
| 502 |
template<typename _ForwardIterator, typename _StrictWeakOrdering> |
| 503 |
bool |
| 504 |
is_sorted(_ForwardIterator __first, _ForwardIterator __last, |
| 505 |
_StrictWeakOrdering __comp) |
| 506 |
{ |
| 507 |
// concept requirements |
| 508 |
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>) |
| 509 |
__glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering, |
| 510 |
typename std::iterator_traits<_ForwardIterator>::value_type, |
| 511 |
typename std::iterator_traits<_ForwardIterator>::value_type>) |
| 512 |
__glibcxx_requires_valid_range(__first, __last); |
| 513 |
|
| 514 |
if (__first == __last) |
| 515 |
return true; |
| 516 |
|
| 517 |
_ForwardIterator __next = __first; |
| 518 |
for (++__next; __next != __last; __first = __next, ++__next) |
| 519 |
if (__comp(*__next, *__first)) |
| 520 |
return false; |
| 521 |
return true; |
| 522 |
} |
| 523 |
#endif // C++11 |
| 524 |
|
| 525 |
/** |
| 526 |
* @brief Find the median of three values. |
| 527 |
* @param __a A value. |
| 528 |
* @param __b A value. |
| 529 |
* @param __c A value. |
| 530 |
* @return One of @p a, @p b or @p c. |
| 531 |
* |
| 532 |
* If @c {l,m,n} is some convolution of @p {a,b,c} such that @c l<=m<=n |
| 533 |
* then the value returned will be @c m. |
| 534 |
* This is an SGI extension. |
| 535 |
* @ingroup SGIextensions |
| 536 |
*/ |
| 537 |
template<typename _Tp> |
| 538 |
const _Tp& |
| 539 |
__median(const _Tp& __a, const _Tp& __b, const _Tp& __c) |
| 540 |
{ |
| 541 |
// concept requirements |
| 542 |
__glibcxx_function_requires(_LessThanComparableConcept<_Tp>) |
| 543 |
if (__a < __b) |
| 544 |
if (__b < __c) |
| 545 |
return __b; |
| 546 |
else if (__a < __c) |
| 547 |
return __c; |
| 548 |
else |
| 549 |
return __a; |
| 550 |
else if (__a < __c) |
| 551 |
return __a; |
| 552 |
else if (__b < __c) |
| 553 |
return __c; |
| 554 |
else |
| 555 |
return __b; |
| 556 |
} |
| 557 |
|
| 558 |
/** |
| 559 |
* @brief Find the median of three values using a predicate for comparison. |
| 560 |
* @param __a A value. |
| 561 |
* @param __b A value. |
| 562 |
* @param __c A value. |
| 563 |
* @param __comp A binary predicate. |
| 564 |
* @return One of @p a, @p b or @p c. |
| 565 |
* |
| 566 |
* If @c {l,m,n} is some convolution of @p {a,b,c} such that @p comp(l,m) |
| 567 |
* and @p comp(m,n) are both true then the value returned will be @c m. |
| 568 |
* This is an SGI extension. |
| 569 |
* @ingroup SGIextensions |
| 570 |
*/ |
| 571 |
template<typename _Tp, typename _Compare> |
| 572 |
const _Tp& |
| 573 |
__median(const _Tp& __a, const _Tp& __b, const _Tp& __c, _Compare __comp) |
| 574 |
{ |
| 575 |
// concept requirements |
| 576 |
__glibcxx_function_requires(_BinaryFunctionConcept<_Compare, bool, |
| 577 |
_Tp, _Tp>) |
| 578 |
if (__comp(__a, __b)) |
| 579 |
if (__comp(__b, __c)) |
| 580 |
return __b; |
| 581 |
else if (__comp(__a, __c)) |
| 582 |
return __c; |
| 583 |
else |
| 584 |
return __a; |
| 585 |
else if (__comp(__a, __c)) |
| 586 |
return __a; |
| 587 |
else if (__comp(__b, __c)) |
| 588 |
return __c; |
| 589 |
else |
| 590 |
return __b; |
| 591 |
} |
| 592 |
|
| 593 |
_GLIBCXX_END_NAMESPACE_VERSION |
| 594 |
} // namespace |
| 595 |
|
| 596 |
#endif /* _EXT_ALGORITHM */ |
