1 // Algorithm extensions -*- C++ -*-
3 // Copyright (C) 2001, 2002 Free Software Foundation, Inc.
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)
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.
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, 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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.
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45 * Silicon Graphics Computer Systems, Inc.
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56 /** @file ext/algorithm
57 * This file is a GNU extension to the Standard C++ Library (possibly
58 * containing extensions from the HP/SGI STL subset). You should only
59 * include this header if you are using GCC 3 or later.
62 #ifndef _EXT_ALGORITHM
63 #define _EXT_ALGORITHM
65 #pragma GCC system_header
73 using std::input_iterator_tag;
74 using std::random_access_iterator_tag;
75 using std::iterator_traits;
77 //--------------------------------------------------
78 // copy_n (not part of the C++ standard)
80 template<typename _InputIter, typename _Size, typename _OutputIter>
81 pair<_InputIter, _OutputIter>
82 __copy_n(_InputIter __first, _Size __count,
86 for ( ; __count > 0; --__count) {
91 return pair<_InputIter, _OutputIter>(__first, __result);
94 template<typename _RAIter, typename _Size, typename _OutputIter>
95 inline pair<_RAIter, _OutputIter>
96 __copy_n(_RAIter __first, _Size __count,
98 random_access_iterator_tag)
100 _RAIter __last = __first + __count;
101 return pair<_RAIter, _OutputIter>(__last,
102 std::copy(__first, __last, __result));
106 * @brief Copies the range [first,first+count) into [result,result+count).
107 * @param first An input iterator.
108 * @param count The number of elements to copy.
109 * @param result An output iterator.
110 * @return A std::pair composed of first+count and result+count.
112 * This is an SGI extension.
113 * This inline function will boil down to a call to @c memmove whenever
114 * possible. Failing that, if random access iterators are passed, then the
115 * loop count will be known (and therefore a candidate for compiler
116 * optimizations such as unrolling).
117 * @ingroup SGIextensions
119 template<typename _InputIter, typename _Size, typename _OutputIter>
120 inline pair<_InputIter, _OutputIter>
121 copy_n(_InputIter __first, _Size __count, _OutputIter __result)
123 // concept requirements
124 __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
125 __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
126 typename iterator_traits<_InputIter>::value_type>)
128 return __copy_n(__first, __count, __result,
129 std::__iterator_category(__first));
132 template<typename _InputIter1, typename _InputIter2>
134 __lexicographical_compare_3way(_InputIter1 __first1, _InputIter1 __last1,
135 _InputIter2 __first2, _InputIter2 __last2)
137 while (__first1 != __last1 && __first2 != __last2) {
138 if (*__first1 < *__first2)
140 if (*__first2 < *__first1)
145 if (__first2 == __last2) {
146 return !(__first1 == __last1);
154 __lexicographical_compare_3way(const unsigned char* __first1,
155 const unsigned char* __last1,
156 const unsigned char* __first2,
157 const unsigned char* __last2)
159 const ptrdiff_t __len1 = __last1 - __first1;
160 const ptrdiff_t __len2 = __last2 - __first2;
161 const int __result = std::memcmp(__first1, __first2, min(__len1, __len2));
162 return __result != 0 ? __result
163 : (__len1 == __len2 ? 0 : (__len1 < __len2 ? -1 : 1));
167 __lexicographical_compare_3way(const char* __first1, const char* __last1,
168 const char* __first2, const char* __last2)
170 #if CHAR_MAX == SCHAR_MAX
171 return __lexicographical_compare_3way(
172 (const signed char*) __first1,
173 (const signed char*) __last1,
174 (const signed char*) __first2,
175 (const signed char*) __last2);
177 return __lexicographical_compare_3way((const unsigned char*) __first1,
178 (const unsigned char*) __last1,
179 (const unsigned char*) __first2,
180 (const unsigned char*) __last2);
185 * @brief @c memcmp on steroids.
186 * @param first1 An input iterator.
187 * @param last1 An input iterator.
188 * @param first2 An input iterator.
189 * @param last2 An input iterator.
190 * @return An int, as with @c memcmp.
192 * The return value will be less than zero if the first range is
193 * "lexigraphically less than" the second, greater than zero if the second
194 * range is "lexigraphically less than" the first, and zero otherwise.
195 * This is an SGI extension.
196 * @ingroup SGIextensions
198 template<typename _InputIter1, typename _InputIter2>
200 lexicographical_compare_3way(_InputIter1 __first1, _InputIter1 __last1,
201 _InputIter2 __first2, _InputIter2 __last2)
203 // concept requirements
204 __glibcpp_function_requires(_InputIteratorConcept<_InputIter1>)
205 __glibcpp_function_requires(_InputIteratorConcept<_InputIter2>)
206 __glibcpp_function_requires(_LessThanComparableConcept<
207 typename iterator_traits<_InputIter1>::value_type>)
208 __glibcpp_function_requires(_LessThanComparableConcept<
209 typename iterator_traits<_InputIter2>::value_type>)
211 return __lexicographical_compare_3way(__first1, __last1, __first2, __last2);
214 // count and count_if: this version, whose return type is void, was present
215 // in the HP STL, and is retained as an extension for backward compatibility.
217 template<typename _InputIter, typename _Tp, typename _Size>
219 count(_InputIter __first, _InputIter __last,
223 // concept requirements
224 __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
225 __glibcpp_function_requires(_EqualityComparableConcept<
226 typename iterator_traits<_InputIter>::value_type >)
227 __glibcpp_function_requires(_EqualityComparableConcept<_Tp>)
228 for ( ; __first != __last; ++__first)
229 if (*__first == __value)
233 template<typename _InputIter, typename _Predicate, typename _Size>
235 count_if(_InputIter __first, _InputIter __last,
239 // concept requirements
240 __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
241 __glibcpp_function_requires(_UnaryPredicateConcept<_Predicate,
242 typename iterator_traits<_InputIter>::value_type>)
243 for ( ; __first != __last; ++__first)
244 if (__pred(*__first))
248 // random_sample and random_sample_n (extensions, not part of the standard).
250 template<typename _ForwardIter, typename _OutputIter, typename _Distance>
252 random_sample_n(_ForwardIter __first, _ForwardIter __last,
253 _OutputIter __out, const _Distance __n)
255 // concept requirements
256 __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
257 __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
258 typename iterator_traits<_ForwardIter>::value_type>)
260 _Distance __remaining = std::distance(__first, __last);
261 _Distance __m = min(__n, __remaining);
264 if (std::__random_number(__remaining) < __m) {
276 template<typename _ForwardIter, typename _OutputIter, typename _Distance,
277 typename _RandomNumberGenerator>
279 random_sample_n(_ForwardIter __first, _ForwardIter __last,
280 _OutputIter __out, const _Distance __n,
281 _RandomNumberGenerator& __rand)
283 // concept requirements
284 __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
285 __glibcpp_function_requires(_OutputIteratorConcept<_OutputIter,
286 typename iterator_traits<_ForwardIter>::value_type>)
287 __glibcpp_function_requires(_UnaryFunctionConcept<
288 _RandomNumberGenerator, _Distance, _Distance>)
290 _Distance __remaining = std::distance(__first, __last);
291 _Distance __m = min(__n, __remaining);
294 if (__rand(__remaining) < __m) {
306 template<typename _InputIter, typename _RandomAccessIter, typename _Distance>
308 __random_sample(_InputIter __first, _InputIter __last,
309 _RandomAccessIter __out,
314 for ( ; __first != __last && __m < __n; ++__m, ++__first)
315 __out[__m] = *__first;
317 while (__first != __last) {
319 _Distance __M = std::__random_number(__t);
321 __out[__M] = *__first;
328 template<typename _InputIter, typename _RandomAccessIter,
329 typename _RandomNumberGenerator, typename _Distance>
331 __random_sample(_InputIter __first, _InputIter __last,
332 _RandomAccessIter __out,
333 _RandomNumberGenerator& __rand,
336 // concept requirements
337 __glibcpp_function_requires(_UnaryFunctionConcept<
338 _RandomNumberGenerator, _Distance, _Distance>)
342 for ( ; __first != __last && __m < __n; ++__m, ++__first)
343 __out[__m] = *__first;
345 while (__first != __last) {
347 _Distance __M = __rand(__t);
349 __out[__M] = *__first;
356 template<typename _InputIter, typename _RandomAccessIter>
357 inline _RandomAccessIter
358 random_sample(_InputIter __first, _InputIter __last,
359 _RandomAccessIter __out_first, _RandomAccessIter __out_last)
361 // concept requirements
362 __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
363 __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
366 return __random_sample(__first, __last,
367 __out_first, __out_last - __out_first);
370 template<typename _InputIter, typename _RandomAccessIter,
371 typename _RandomNumberGenerator>
372 inline _RandomAccessIter
373 random_sample(_InputIter __first, _InputIter __last,
374 _RandomAccessIter __out_first, _RandomAccessIter __out_last,
375 _RandomNumberGenerator& __rand)
377 // concept requirements
378 __glibcpp_function_requires(_InputIteratorConcept<_InputIter>)
379 __glibcpp_function_requires(_Mutable_RandomAccessIteratorConcept<
382 return __random_sample(__first, __last,
384 __out_last - __out_first);
387 // is_heap, a predicate testing whether or not a range is
388 // a heap. This function is an extension, not part of the C++
391 template<typename _RandomAccessIter, typename _Distance>
393 __is_heap(_RandomAccessIter __first, _Distance __n)
395 _Distance __parent = 0;
396 for (_Distance __child = 1; __child < __n; ++__child) {
397 if (__first[__parent] < __first[__child])
399 if ((__child & 1) == 0)
405 template<typename _RandomAccessIter, typename _Distance,
406 typename _StrictWeakOrdering>
408 __is_heap(_RandomAccessIter __first, _StrictWeakOrdering __comp,
411 _Distance __parent = 0;
412 for (_Distance __child = 1; __child < __n; ++__child) {
413 if (__comp(__first[__parent], __first[__child]))
415 if ((__child & 1) == 0)
421 template<typename _RandomAccessIter>
423 is_heap(_RandomAccessIter __first, _RandomAccessIter __last)
425 // concept requirements
426 __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIter>)
427 __glibcpp_function_requires(_LessThanComparableConcept<
428 typename iterator_traits<_RandomAccessIter>::value_type>)
430 return __is_heap(__first, __last - __first);
433 template<typename _RandomAccessIter, typename _StrictWeakOrdering>
435 is_heap(_RandomAccessIter __first, _RandomAccessIter __last,
436 _StrictWeakOrdering __comp)
438 // concept requirements
439 __glibcpp_function_requires(_RandomAccessIteratorConcept<_RandomAccessIter>)
440 __glibcpp_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
441 typename iterator_traits<_RandomAccessIter>::value_type,
442 typename iterator_traits<_RandomAccessIter>::value_type>)
444 return __is_heap(__first, __comp, __last - __first);
447 // is_sorted, a predicated testing whether a range is sorted in
448 // nondescending order. This is an extension, not part of the C++
451 template<typename _ForwardIter>
453 is_sorted(_ForwardIter __first, _ForwardIter __last)
455 // concept requirements
456 __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
457 __glibcpp_function_requires(_LessThanComparableConcept<
458 typename iterator_traits<_ForwardIter>::value_type>)
460 if (__first == __last)
463 _ForwardIter __next = __first;
464 for (++__next; __next != __last; __first = __next, ++__next) {
465 if (*__next < *__first)
472 template<typename _ForwardIter, typename _StrictWeakOrdering>
474 is_sorted(_ForwardIter __first, _ForwardIter __last, _StrictWeakOrdering __comp)
476 // concept requirements
477 __glibcpp_function_requires(_ForwardIteratorConcept<_ForwardIter>)
478 __glibcpp_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
479 typename iterator_traits<_ForwardIter>::value_type,
480 typename iterator_traits<_ForwardIter>::value_type>)
482 if (__first == __last)
485 _ForwardIter __next = __first;
486 for (++__next; __next != __last; __first = __next, ++__next) {
487 if (__comp(*__next, *__first))
494 } // namespace __gnu_cxx
496 #endif /* _EXT_ALGORITHM */