1 // Bits and pieces used in algorithms -*- C++ -*-
3 // Copyright (C) 2001, 2002, 2003, 2004 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.
33 * Hewlett-Packard Company
35 * Permission to use, copy, modify, distribute and sell this software
36 * and its documentation for any purpose is hereby granted without fee,
37 * provided that the above copyright notice appear in all copies and
38 * that both that copyright notice and this permission notice appear
39 * in supporting documentation. Hewlett-Packard Company makes no
40 * representations about the suitability of this software for any
41 * purpose. It is provided "as is" without express or implied warranty.
44 * Copyright (c) 1996-1998
45 * Silicon Graphics Computer Systems, Inc.
47 * Permission to use, copy, modify, distribute and sell this software
48 * and its documentation for any purpose is hereby granted without fee,
49 * provided that the above copyright notice appear in all copies and
50 * that both that copyright notice and this permission notice appear
51 * in supporting documentation. Silicon Graphics makes no
52 * representations about the suitability of this software for any
53 * purpose. It is provided "as is" without express or implied warranty.
56 /** @file stl_algobase.h
57 * This is an internal header file, included by other library headers.
58 * You should not attempt to use it directly.
64 #include <bits/c++config.h>
71 #include <bits/stl_pair.h>
72 #include <bits/type_traits.h>
73 #include <bits/stl_iterator_base_types.h>
74 #include <bits/stl_iterator_base_funcs.h>
75 #include <bits/stl_iterator.h>
76 #include <bits/concept_check.h>
77 #include <debug/debug.h>
82 * @brief Swaps the contents of two iterators.
83 * @param a An iterator.
84 * @param b Another iterator.
87 * This function swaps the values pointed to by two iterators, not the
88 * iterators themselves.
90 template<typename _ForwardIterator1, typename _ForwardIterator2>
92 iter_swap(_ForwardIterator1 __a, _ForwardIterator2 __b)
94 typedef typename iterator_traits<_ForwardIterator1>::value_type
96 typedef typename iterator_traits<_ForwardIterator2>::value_type
99 // concept requirements
100 __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
102 __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
104 __glibcxx_function_requires(_ConvertibleConcept<_ValueType1,
106 __glibcxx_function_requires(_ConvertibleConcept<_ValueType2,
109 const _ValueType1 __tmp = *__a;
115 * @brief Swaps two values.
116 * @param a A thing of arbitrary type.
117 * @param b Another thing of arbitrary type.
120 * This is the simple classic generic implementation. It will work on
121 * any type which has a copy constructor and an assignment operator.
123 template<typename _Tp>
125 swap(_Tp& __a, _Tp& __b)
127 // concept requirements
128 __glibcxx_function_requires(_SGIAssignableConcept<_Tp>)
130 const _Tp __tmp = __a;
139 * @brief This does what you think it does.
140 * @param a A thing of arbitrary type.
141 * @param b Another thing of arbitrary type.
142 * @return The lesser of the parameters.
144 * This is the simple classic generic implementation. It will work on
145 * temporary expressions, since they are only evaluated once, unlike a
146 * preprocessor macro.
148 template<typename _Tp>
150 min(const _Tp& __a, const _Tp& __b)
152 // concept requirements
153 __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
154 //return __b < __a ? __b : __a;
161 * @brief This does what you think it does.
162 * @param a A thing of arbitrary type.
163 * @param b Another thing of arbitrary type.
164 * @return The greater of the parameters.
166 * This is the simple classic generic implementation. It will work on
167 * temporary expressions, since they are only evaluated once, unlike a
168 * preprocessor macro.
170 template<typename _Tp>
172 max(const _Tp& __a, const _Tp& __b)
174 // concept requirements
175 __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
176 //return __a < __b ? __b : __a;
183 * @brief This does what you think it does.
184 * @param a A thing of arbitrary type.
185 * @param b Another thing of arbitrary type.
186 * @param comp A @link s20_3_3_comparisons comparison functor@endlink.
187 * @return The lesser of the parameters.
189 * This will work on temporary expressions, since they are only evaluated
190 * once, unlike a preprocessor macro.
192 template<typename _Tp, typename _Compare>
194 min(const _Tp& __a, const _Tp& __b, _Compare __comp)
196 //return __comp(__b, __a) ? __b : __a;
197 if (__comp(__b, __a))
203 * @brief This does what you think it does.
204 * @param a A thing of arbitrary type.
205 * @param b Another thing of arbitrary type.
206 * @param comp A @link s20_3_3_comparisons comparison functor@endlink.
207 * @return The greater of the parameters.
209 * This will work on temporary expressions, since they are only evaluated
210 * once, unlike a preprocessor macro.
212 template<typename _Tp, typename _Compare>
214 max(const _Tp& __a, const _Tp& __b, _Compare __comp)
216 //return __comp(__a, __b) ? __b : __a;
217 if (__comp(__a, __b))
222 // All of these auxiliary functions serve two purposes. (1) Replace
223 // calls to copy with memmove whenever possible. (Memmove, not memcpy,
224 // because the input and output ranges are permitted to overlap.)
225 // (2) If we're using random access iterators, then write the loop as
226 // a for loop with an explicit count.
228 template<typename _InputIterator, typename _OutputIterator>
229 inline _OutputIterator
230 __copy(_InputIterator __first, _InputIterator __last,
231 _OutputIterator __result, input_iterator_tag)
233 for (; __first != __last; ++__result, ++__first)
234 *__result = *__first;
238 template<typename _RandomAccessIterator, typename _OutputIterator>
239 inline _OutputIterator
240 __copy(_RandomAccessIterator __first, _RandomAccessIterator __last,
241 _OutputIterator __result, random_access_iterator_tag)
243 typedef typename iterator_traits<_RandomAccessIterator>::difference_type
245 for (_Distance __n = __last - __first; __n > 0; --__n)
247 *__result = *__first;
254 template<typename _Tp>
256 __copy_trivial(const _Tp* __first, const _Tp* __last, _Tp* __result)
258 std::memmove(__result, __first, sizeof(_Tp) * (__last - __first));
259 return __result + (__last - __first);
262 template<typename _InputIterator, typename _OutputIterator>
263 inline _OutputIterator
264 __copy_aux2(_InputIterator __first, _InputIterator __last,
265 _OutputIterator __result, __false_type)
266 { return std::__copy(__first, __last, __result,
267 std::__iterator_category(__first)); }
269 template<typename _InputIterator, typename _OutputIterator>
270 inline _OutputIterator
271 __copy_aux2(_InputIterator __first, _InputIterator __last,
272 _OutputIterator __result, __true_type)
273 { return std::__copy(__first, __last, __result,
274 std::__iterator_category(__first)); }
276 template<typename _Tp>
278 __copy_aux2(_Tp* __first, _Tp* __last, _Tp* __result, __true_type)
279 { return std::__copy_trivial(__first, __last, __result); }
281 template<typename _Tp>
283 __copy_aux2(const _Tp* __first, const _Tp* __last, _Tp* __result,
285 { return std::__copy_trivial(__first, __last, __result); }
287 template<typename _InputIterator, typename _OutputIterator>
288 inline _OutputIterator
289 __copy_ni2(_InputIterator __first, _InputIterator __last,
290 _OutputIterator __result, __true_type)
292 typedef typename iterator_traits<_InputIterator>::value_type
294 typedef typename __type_traits<
295 _ValueType>::has_trivial_assignment_operator _Trivial;
296 return _OutputIterator(std::__copy_aux2(__first, __last, __result.base(),
300 template<typename _InputIterator, typename _OutputIterator>
301 inline _OutputIterator
302 __copy_ni2(_InputIterator __first, _InputIterator __last,
303 _OutputIterator __result, __false_type)
305 typedef typename iterator_traits<_InputIterator>::value_type _ValueType;
306 typedef typename __type_traits<
307 _ValueType>::has_trivial_assignment_operator _Trivial;
308 return std::__copy_aux2(__first, __last, __result, _Trivial());
311 template<typename _InputIterator, typename _OutputIterator>
312 inline _OutputIterator
313 __copy_ni1(_InputIterator __first, _InputIterator __last,
314 _OutputIterator __result, __true_type)
316 typedef typename _Is_normal_iterator<_OutputIterator>::_Normal __Normal;
317 return std::__copy_ni2(__first.base(), __last.base(),
318 __result, __Normal());
321 template<typename _InputIterator, typename _OutputIterator>
322 inline _OutputIterator
323 __copy_ni1(_InputIterator __first, _InputIterator __last,
324 _OutputIterator __result, __false_type)
326 typedef typename _Is_normal_iterator<_OutputIterator>::_Normal __Normal;
327 return std::__copy_ni2(__first, __last, __result, __Normal());
331 * @brief Copies the range [first,last) into result.
332 * @param first An input iterator.
333 * @param last An input iterator.
334 * @param result An output iterator.
335 * @return result + (first - last)
337 * This inline function will boil down to a call to @c memmove whenever
338 * possible. Failing that, if random access iterators are passed, then the
339 * loop count will be known (and therefore a candidate for compiler
340 * optimizations such as unrolling). Result may not be contained within
341 * [first,last); the copy_backward function should be used instead.
343 * Note that the end of the output range is permitted to be contained
344 * within [first,last).
346 template<typename _InputIterator, typename _OutputIterator>
347 inline _OutputIterator
348 copy(_InputIterator __first, _InputIterator __last,
349 _OutputIterator __result)
351 // concept requirements
352 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
353 __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
354 typename iterator_traits<_InputIterator>::value_type>)
355 __glibcxx_requires_valid_range(__first, __last);
357 typedef typename _Is_normal_iterator<_InputIterator>::_Normal __Normal;
358 return std::__copy_ni1(__first, __last, __result, __Normal());
361 template<typename _BidirectionalIterator1, typename _BidirectionalIterator2>
362 inline _BidirectionalIterator2
363 __copy_backward(_BidirectionalIterator1 __first,
364 _BidirectionalIterator1 __last,
365 _BidirectionalIterator2 __result,
366 bidirectional_iterator_tag)
368 while (__first != __last)
369 *--__result = *--__last;
373 template<typename _RandomAccessIterator, typename _BidirectionalIterator>
374 inline _BidirectionalIterator
375 __copy_backward(_RandomAccessIterator __first, _RandomAccessIterator __last,
376 _BidirectionalIterator __result, random_access_iterator_tag)
378 typename iterator_traits<_RandomAccessIterator>::difference_type __n;
379 for (__n = __last - __first; __n > 0; --__n)
380 *--__result = *--__last;
385 // This dispatch class is a workaround for compilers that do not
386 // have partial ordering of function templates. All we're doing is
387 // creating a specialization so that we can turn a call to copy_backward
388 // into a memmove whenever possible.
389 template<typename _BidirectionalIterator1, typename _BidirectionalIterator2,
391 struct __copy_backward_dispatch
393 static _BidirectionalIterator2
394 copy(_BidirectionalIterator1 __first, _BidirectionalIterator1 __last,
395 _BidirectionalIterator2 __result)
396 { return std::__copy_backward(__first, __last, __result,
397 std::__iterator_category(__first)); }
400 template<typename _Tp>
401 struct __copy_backward_dispatch<_Tp*, _Tp*, __true_type>
404 copy(const _Tp* __first, const _Tp* __last, _Tp* __result)
406 const ptrdiff_t _Num = __last - __first;
407 std::memmove(__result - _Num, __first, sizeof(_Tp) * _Num);
408 return __result - _Num;
412 template<typename _Tp>
413 struct __copy_backward_dispatch<const _Tp*, _Tp*, __true_type>
416 copy(const _Tp* __first, const _Tp* __last, _Tp* __result)
418 return std::__copy_backward_dispatch<_Tp*, _Tp*, __true_type>
419 ::copy(__first, __last, __result);
423 template<typename _BI1, typename _BI2>
425 __copy_backward_aux(_BI1 __first, _BI1 __last, _BI2 __result)
427 typedef typename __type_traits<typename iterator_traits<_BI2>::value_type>
428 ::has_trivial_assignment_operator _Trivial;
430 std::__copy_backward_dispatch<_BI1, _BI2, _Trivial>::copy(__first,
435 template <typename _BI1, typename _BI2>
437 __copy_backward_output_normal_iterator(_BI1 __first, _BI1 __last,
438 _BI2 __result, __true_type)
439 { return _BI2(std::__copy_backward_aux(__first, __last, __result.base())); }
441 template <typename _BI1, typename _BI2>
443 __copy_backward_output_normal_iterator(_BI1 __first, _BI1 __last,
444 _BI2 __result, __false_type)
445 { return std::__copy_backward_aux(__first, __last, __result); }
447 template <typename _BI1, typename _BI2>
449 __copy_backward_input_normal_iterator(_BI1 __first, _BI1 __last,
450 _BI2 __result, __true_type)
452 typedef typename _Is_normal_iterator<_BI2>::_Normal __Normal;
453 return std::__copy_backward_output_normal_iterator(__first.base(),
455 __result, __Normal());
458 template <typename _BI1, typename _BI2>
460 __copy_backward_input_normal_iterator(_BI1 __first, _BI1 __last,
461 _BI2 __result, __false_type)
463 typedef typename _Is_normal_iterator<_BI2>::_Normal __Normal;
464 return std::__copy_backward_output_normal_iterator(__first, __last,
465 __result, __Normal());
469 * @brief Copies the range [first,last) into result.
470 * @param first A bidirectional iterator.
471 * @param last A bidirectional iterator.
472 * @param result A bidirectional iterator.
473 * @return result - (first - last)
475 * The function has the same effect as copy, but starts at the end of the
476 * range and works its way to the start, returning the start of the result.
477 * This inline function will boil down to a call to @c memmove whenever
478 * possible. Failing that, if random access iterators are passed, then the
479 * loop count will be known (and therefore a candidate for compiler
480 * optimizations such as unrolling).
482 * Result may not be in the range [first,last). Use copy instead. Note
483 * that the start of the output range may overlap [first,last).
485 template <typename _BI1, typename _BI2>
487 copy_backward(_BI1 __first, _BI1 __last, _BI2 __result)
489 // concept requirements
490 __glibcxx_function_requires(_BidirectionalIteratorConcept<_BI1>)
491 __glibcxx_function_requires(_Mutable_BidirectionalIteratorConcept<_BI2>)
492 __glibcxx_function_requires(_ConvertibleConcept<
493 typename iterator_traits<_BI1>::value_type,
494 typename iterator_traits<_BI2>::value_type>)
495 __glibcxx_requires_valid_range(__first, __last);
497 typedef typename _Is_normal_iterator<_BI1>::_Normal __Normal;
498 return std::__copy_backward_input_normal_iterator(__first, __last,
499 __result, __Normal());
504 * @brief Fills the range [first,last) with copies of value.
505 * @param first A forward iterator.
506 * @param last A forward iterator.
507 * @param value A reference-to-const of arbitrary type.
510 * This function fills a range with copies of the same value. For one-byte
511 * types filling contiguous areas of memory, this becomes an inline call to
514 template<typename _ForwardIterator, typename _Tp>
516 fill(_ForwardIterator __first, _ForwardIterator __last, const _Tp& __value)
518 // concept requirements
519 __glibcxx_function_requires(_Mutable_ForwardIteratorConcept<
521 __glibcxx_requires_valid_range(__first, __last);
523 for ( ; __first != __last; ++__first)
528 * @brief Fills the range [first,first+n) with copies of value.
529 * @param first An output iterator.
530 * @param n The count of copies to perform.
531 * @param value A reference-to-const of arbitrary type.
532 * @return The iterator at first+n.
534 * This function fills a range with copies of the same value. For one-byte
535 * types filling contiguous areas of memory, this becomes an inline call to
538 template<typename _OutputIterator, typename _Size, typename _Tp>
540 fill_n(_OutputIterator __first, _Size __n, const _Tp& __value)
542 // concept requirements
543 __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,_Tp>)
545 for ( ; __n > 0; --__n, ++__first)
550 // Specialization: for one-byte types we can use memset.
552 fill(unsigned char* __first, unsigned char* __last, const unsigned char& __c)
554 __glibcxx_requires_valid_range(__first, __last);
555 const unsigned char __tmp = __c;
556 std::memset(__first, __tmp, __last - __first);
560 fill(signed char* __first, signed char* __last, const signed char& __c)
562 __glibcxx_requires_valid_range(__first, __last);
563 const signed char __tmp = __c;
564 std::memset(__first, static_cast<unsigned char>(__tmp), __last - __first);
568 fill(char* __first, char* __last, const char& __c)
570 __glibcxx_requires_valid_range(__first, __last);
571 const char __tmp = __c;
572 std::memset(__first, static_cast<unsigned char>(__tmp), __last - __first);
575 template<typename _Size>
576 inline unsigned char*
577 fill_n(unsigned char* __first, _Size __n, const unsigned char& __c)
579 std::fill(__first, __first + __n, __c);
580 return __first + __n;
583 template<typename _Size>
585 fill_n(char* __first, _Size __n, const signed char& __c)
587 std::fill(__first, __first + __n, __c);
588 return __first + __n;
591 template<typename _Size>
593 fill_n(char* __first, _Size __n, const char& __c)
595 std::fill(__first, __first + __n, __c);
596 return __first + __n;
601 * @brief Finds the places in ranges which don't match.
602 * @param first1 An input iterator.
603 * @param last1 An input iterator.
604 * @param first2 An input iterator.
605 * @return A pair of iterators pointing to the first mismatch.
607 * This compares the elements of two ranges using @c == and returns a pair
608 * of iterators. The first iterator points into the first range, the
609 * second iterator points into the second range, and the elements pointed
610 * to by the iterators are not equal.
612 template<typename _InputIterator1, typename _InputIterator2>
613 pair<_InputIterator1, _InputIterator2>
614 mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
615 _InputIterator2 __first2)
617 // concept requirements
618 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
619 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
620 __glibcxx_function_requires(_EqualityComparableConcept<
621 typename iterator_traits<_InputIterator1>::value_type>)
622 __glibcxx_function_requires(_EqualityComparableConcept<
623 typename iterator_traits<_InputIterator2>::value_type>)
624 __glibcxx_requires_valid_range(__first1, __last1);
626 while (__first1 != __last1 && *__first1 == *__first2)
631 return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
635 * @brief Finds the places in ranges which don't match.
636 * @param first1 An input iterator.
637 * @param last1 An input iterator.
638 * @param first2 An input iterator.
639 * @param binary_pred A binary predicate @link s20_3_1_base functor@endlink.
640 * @return A pair of iterators pointing to the first mismatch.
642 * This compares the elements of two ranges using the binary_pred
643 * parameter, and returns a pair
644 * of iterators. The first iterator points into the first range, the
645 * second iterator points into the second range, and the elements pointed
646 * to by the iterators are not equal.
648 template<typename _InputIterator1, typename _InputIterator2,
649 typename _BinaryPredicate>
650 pair<_InputIterator1, _InputIterator2>
651 mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
652 _InputIterator2 __first2, _BinaryPredicate __binary_pred)
654 // concept requirements
655 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
656 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
657 __glibcxx_requires_valid_range(__first1, __last1);
659 while (__first1 != __last1 && __binary_pred(*__first1, *__first2))
664 return pair<_InputIterator1, _InputIterator2>(__first1, __first2);
668 * @brief Tests a range for element-wise equality.
669 * @param first1 An input iterator.
670 * @param last1 An input iterator.
671 * @param first2 An input iterator.
672 * @return A boolean true or false.
674 * This compares the elements of two ranges using @c == and returns true or
675 * false depending on whether all of the corresponding elements of the
678 template<typename _InputIterator1, typename _InputIterator2>
680 equal(_InputIterator1 __first1, _InputIterator1 __last1,
681 _InputIterator2 __first2)
683 // concept requirements
684 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
685 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
686 __glibcxx_function_requires(_EqualOpConcept<
687 typename iterator_traits<_InputIterator1>::value_type,
688 typename iterator_traits<_InputIterator2>::value_type>)
689 __glibcxx_requires_valid_range(__first1, __last1);
691 for ( ; __first1 != __last1; ++__first1, ++__first2)
692 if (!(*__first1 == *__first2))
698 * @brief Tests a range for element-wise equality.
699 * @param first1 An input iterator.
700 * @param last1 An input iterator.
701 * @param first2 An input iterator.
702 * @param binary_pred A binary predicate @link s20_3_1_base functor@endlink.
703 * @return A boolean true or false.
705 * This compares the elements of two ranges using the binary_pred
706 * parameter, and returns true or
707 * false depending on whether all of the corresponding elements of the
710 template<typename _InputIterator1, typename _InputIterator2,
711 typename _BinaryPredicate>
713 equal(_InputIterator1 __first1, _InputIterator1 __last1,
714 _InputIterator2 __first2,
715 _BinaryPredicate __binary_pred)
717 // concept requirements
718 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
719 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
720 __glibcxx_requires_valid_range(__first1, __last1);
722 for ( ; __first1 != __last1; ++__first1, ++__first2)
723 if (!__binary_pred(*__first1, *__first2))
729 * @brief Performs "dictionary" comparison on ranges.
730 * @param first1 An input iterator.
731 * @param last1 An input iterator.
732 * @param first2 An input iterator.
733 * @param last2 An input iterator.
734 * @return A boolean true or false.
736 * "Returns true if the sequence of elements defined by the range
737 * [first1,last1) is lexicographically less than the sequence of elements
738 * defined by the range [first2,last2). Returns false otherwise."
739 * (Quoted from [25.3.8]/1.) If the iterators are all character pointers,
740 * then this is an inline call to @c memcmp.
742 template<typename _InputIterator1, typename _InputIterator2>
744 lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
745 _InputIterator2 __first2, _InputIterator2 __last2)
747 // concept requirements
748 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
749 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
750 __glibcxx_function_requires(_LessThanComparableConcept<
751 typename iterator_traits<_InputIterator1>::value_type>)
752 __glibcxx_function_requires(_LessThanComparableConcept<
753 typename iterator_traits<_InputIterator2>::value_type>)
754 __glibcxx_requires_valid_range(__first1, __last1);
755 __glibcxx_requires_valid_range(__first2, __last2);
757 for (;__first1 != __last1 && __first2 != __last2; ++__first1, ++__first2)
759 if (*__first1 < *__first2)
761 if (*__first2 < *__first1)
764 return __first1 == __last1 && __first2 != __last2;
768 * @brief Performs "dictionary" comparison on ranges.
769 * @param first1 An input iterator.
770 * @param last1 An input iterator.
771 * @param first2 An input iterator.
772 * @param last2 An input iterator.
773 * @param comp A @link s20_3_3_comparisons comparison functor@endlink.
774 * @return A boolean true or false.
776 * The same as the four-parameter @c lexigraphical_compare, but uses the
777 * comp parameter instead of @c <.
779 template<typename _InputIterator1, typename _InputIterator2,
782 lexicographical_compare(_InputIterator1 __first1, _InputIterator1 __last1,
783 _InputIterator2 __first2, _InputIterator2 __last2,
786 // concept requirements
787 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
788 __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
789 __glibcxx_requires_valid_range(__first1, __last1);
790 __glibcxx_requires_valid_range(__first2, __last2);
792 for ( ; __first1 != __last1 && __first2 != __last2
793 ; ++__first1, ++__first2)
795 if (__comp(*__first1, *__first2))
797 if (__comp(*__first2, *__first1))
800 return __first1 == __last1 && __first2 != __last2;
804 lexicographical_compare(const unsigned char* __first1,
805 const unsigned char* __last1,
806 const unsigned char* __first2,
807 const unsigned char* __last2)
809 __glibcxx_requires_valid_range(__first1, __last1);
810 __glibcxx_requires_valid_range(__first2, __last2);
812 const size_t __len1 = __last1 - __first1;
813 const size_t __len2 = __last2 - __first2;
814 const int __result = std::memcmp(__first1, __first2,
815 std::min(__len1, __len2));
816 return __result != 0 ? __result < 0 : __len1 < __len2;
820 lexicographical_compare(const char* __first1, const char* __last1,
821 const char* __first2, const char* __last2)
823 __glibcxx_requires_valid_range(__first1, __last1);
824 __glibcxx_requires_valid_range(__first2, __last2);
826 #if CHAR_MAX == SCHAR_MAX
827 return std::lexicographical_compare((const signed char*) __first1,
828 (const signed char*) __last1,
829 (const signed char*) __first2,
830 (const signed char*) __last2);
831 #else /* CHAR_MAX == SCHAR_MAX */
832 return std::lexicographical_compare((const unsigned char*) __first1,
833 (const unsigned char*) __last1,
834 (const unsigned char*) __first2,
835 (const unsigned char*) __last2);
836 #endif /* CHAR_MAX == SCHAR_MAX */