# ext/algorithm

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    00001 // Algorithm extensions -*- C++ -*-
    00002
    00003 // Copyright (C) 2001, 2002, 2004, 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
    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).
    00059  */
    00060
    00061 #ifndef _EXT_ALGORITHM
    00062 #define _EXT_ALGORITHM 1
    00063
    00064 #pragma GCC system_header
    00065
    00066 #include <algorithm>
    00067
    00068 _GLIBCXX_BEGIN_NAMESPACE(__gnu_cxx)
    00069
    00070   using std::ptrdiff_t;
    00071   using std::min;
    00072   using std::pair;
    00073   using std::input_iterator_tag;
    00074   using std::random_access_iterator_tag;
    00075   using std::iterator_traits;
    00076
    00077   //--------------------------------------------------
    00078   // copy_n (not part of the C++ standard)
    00079
    00080   template<typename _InputIterator, typename _Size, typename _OutputIterator>
    00081     pair<_InputIterator, _OutputIterator>
    00082     __copy_n(_InputIterator __first, _Size __count,
    00083          _OutputIterator __result,
    00084          input_iterator_tag)
    00085     {
    00086       for ( ; __count > 0; --__count)
    00087     {
    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, std::copy(__first,
    00103                                   __last,
    00104                                   __result));
    00105     }
    00106
    00107   /**
    00108    *  @brief Copies the range [first,first+count) into [result,result+count).
    00109    *  @param  first  An input iterator.
    00110    *  @param  count  The number of elements to copy.
    00111    *  @param  result An output iterator.
    00112    *  @return   A std::pair composed of first+count and result+count.
    00113    *
    00114    *  This is an SGI extension.
    00115    *  This inline function will boil down to a call to @c memmove whenever
    00116    *  possible.  Failing that, if random access iterators are passed, then the
    00117    *  loop count will be known (and therefore a candidate for compiler
    00118    *  optimizations such as unrolling).
    00119    *  @ingroup SGIextensions
    00120   */
    00121   template<typename _InputIterator, typename _Size, typename _OutputIterator>
    00122     inline pair<_InputIterator, _OutputIterator>
    00123     copy_n(_InputIterator __first, _Size __count, _OutputIterator __result)
    00124     {
    00125       // concept requirements
    00126       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00127       __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    00128         typename iterator_traits<_InputIterator>::value_type>)
    00129
    00130       return __copy_n(__first, __count, __result,
    00131               std::__iterator_category(__first));
    00132     }
    00133
    00134   template<typename _InputIterator1, typename _InputIterator2>
    00135     int
    00136     __lexicographical_compare_3way(_InputIterator1 __first1,
    00137                    _InputIterator1 __last1,
    00138                    _InputIterator2 __first2,
    00139                    _InputIterator2 __last2)
    00140     {
    00141       while (__first1 != __last1 && __first2 != __last2)
    00142     {
    00143       if (*__first1 < *__first2)
    00144         return -1;
    00145       if (*__first2 < *__first1)
    00146         return 1;
    00147       ++__first1;
    00148       ++__first2;
    00149     }
    00150       if (__first2 == __last2)
    00151     return !(__first1 == __last1);
    00152       else
    00153     return -1;
    00154     }
    00155
    00156   inline int
    00157   __lexicographical_compare_3way(const unsigned char* __first1,
    00158                  const unsigned char* __last1,
    00159                  const unsigned char* __first2,
    00160                  const unsigned char* __last2)
    00161   {
    00162     const ptrdiff_t __len1 = __last1 - __first1;
    00163     const ptrdiff_t __len2 = __last2 - __first2;
    00164     const int __result = std::memcmp(__first1, __first2, min(__len1, __len2));
    00165     return __result != 0 ? __result
    00166              : (__len1 == __len2 ? 0 : (__len1 < __len2 ? -1 : 1));
    00167   }
    00168
    00169   inline int
    00170   __lexicographical_compare_3way(const char* __first1, const char* __last1,
    00171                  const char* __first2, const char* __last2)
    00172   {
    00173 #if CHAR_MAX == SCHAR_MAX
    00174     return __lexicographical_compare_3way((const signed char*) __first1,
    00175                       (const signed char*) __last1,
    00176                       (const signed char*) __first2,
    00177                       (const signed char*) __last2);
    00178 #else
    00179     return __lexicographical_compare_3way((const unsigned char*) __first1,
    00180                       (const unsigned char*) __last1,
    00181                       (const unsigned char*) __first2,
    00182                       (const unsigned char*) __last2);
    00183 #endif
    00184   }
    00185
    00186   /**
    00187    *  @brief @c memcmp on steroids.
    00188    *  @param  first1  An input iterator.
    00189    *  @param  last1   An input iterator.
    00190    *  @param  first2  An input iterator.
    00191    *  @param  last2   An input iterator.
    00192    *  @return   An int, as with @c memcmp.
    00193    *
    00194    *  The return value will be less than zero if the first range is
    00195    *  "lexigraphically less than" the second, greater than zero if the second
    00196    *  range is "lexigraphically less than" the first, and zero otherwise.
    00197    *  This is an SGI extension.
    00198    *  @ingroup SGIextensions
    00199   */
    00200   template<typename _InputIterator1, typename _InputIterator2>
    00201     int
    00202     lexicographical_compare_3way(_InputIterator1 __first1,
    00203                  _InputIterator1 __last1,
    00204                  _InputIterator2 __first2,
    00205                  _InputIterator2 __last2)
    00206     {
    00207       // concept requirements
    00208       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
    00209       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
    00210       __glibcxx_function_requires(_LessThanComparableConcept<
    00211         typename iterator_traits<_InputIterator1>::value_type>)
    00212       __glibcxx_function_requires(_LessThanComparableConcept<
    00213         typename iterator_traits<_InputIterator2>::value_type>)
    00214       __glibcxx_requires_valid_range(__first1, __last1);
    00215       __glibcxx_requires_valid_range(__first2, __last2);
    00216
    00217       return __lexicographical_compare_3way(__first1, __last1, __first2,
    00218                         __last2);
    00219     }
    00220
    00221   // count and count_if: this version, whose return type is void, was present
    00222   // in the HP STL, and is retained as an extension for backward compatibility.
    00223   template<typename _InputIterator, typename _Tp, typename _Size>
    00224     void
    00225     count(_InputIterator __first, _InputIterator __last,
    00226       const _Tp& __value,
    00227       _Size& __n)
    00228     {
    00229       // concept requirements
    00230       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00231       __glibcxx_function_requires(_EqualityComparableConcept<
    00232         typename iterator_traits<_InputIterator>::value_type >)
    00233       __glibcxx_function_requires(_EqualityComparableConcept<_Tp>)
    00234       __glibcxx_requires_valid_range(__first, __last);
    00235
    00236       for ( ; __first != __last; ++__first)
    00237     if (*__first == __value)
    00238       ++__n;
    00239     }
    00240
    00241   template<typename _InputIterator, typename _Predicate, typename _Size>
    00242     void
    00243     count_if(_InputIterator __first, _InputIterator __last,
    00244          _Predicate __pred,
    00245          _Size& __n)
    00246     {
    00247       // concept requirements
    00248       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00249       __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
    00250         typename iterator_traits<_InputIterator>::value_type>)
    00251       __glibcxx_requires_valid_range(__first, __last);
    00252
    00253       for ( ; __first != __last; ++__first)
    00254     if (__pred(*__first))
    00255       ++__n;
    00256     }
    00257
    00258   // random_sample and random_sample_n (extensions, not part of the standard).
    00259
    00260   /**
    00261    *  This is an SGI extension.
    00262    *  @ingroup SGIextensions
    00263    *  @doctodo
    00264   */
    00265   template<typename _ForwardIterator, typename _OutputIterator,
    00266        typename _Distance>
    00267     _OutputIterator
    00268     random_sample_n(_ForwardIterator __first, _ForwardIterator __last,
    00269                     _OutputIterator __out, const _Distance __n)
    00270     {
    00271       // concept requirements
    00272       __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
    00273       __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    00274         typename iterator_traits<_ForwardIterator>::value_type>)
    00275       __glibcxx_requires_valid_range(__first, __last);
    00276
    00277       _Distance __remaining = std::distance(__first, __last);
    00278       _Distance __m = min(__n, __remaining);
    00279
    00280       while (__m > 0)
    00281     {
    00282       if ((std::rand() % __remaining) < __m)
    00283         {
    00284           *__out = *__first;
    00285           ++__out;
    00286           --__m;
    00287         }
    00288       --__remaining;
    00289       ++__first;
    00290     }
    00291       return __out;
    00292     }
    00293
    00294   /**
    00295    *  This is an SGI extension.
    00296    *  @ingroup SGIextensions
    00297    *  @doctodo
    00298   */
    00299   template<typename _ForwardIterator, typename _OutputIterator,
    00300        typename _Distance, typename _RandomNumberGenerator>
    00301     _OutputIterator
    00302     random_sample_n(_ForwardIterator __first, _ForwardIterator __last,
    00303                    _OutputIterator __out, const _Distance __n,
    00304            _RandomNumberGenerator& __rand)
    00305     {
    00306       // concept requirements
    00307       __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
    00308       __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
    00309         typename iterator_traits<_ForwardIterator>::value_type>)
    00310       __glibcxx_function_requires(_UnaryFunctionConcept<
    00311         _RandomNumberGenerator, _Distance, _Distance>)
    00312       __glibcxx_requires_valid_range(__first, __last);
    00313
    00314       _Distance __remaining = std::distance(__first, __last);
    00315       _Distance __m = min(__n, __remaining);
    00316
    00317       while (__m > 0)
    00318     {
    00319       if (__rand(__remaining) < __m)
    00320         {
    00321           *__out = *__first;
    00322           ++__out;
    00323           --__m;
    00324         }
    00325       --__remaining;
    00326       ++__first;
    00327     }
    00328       return __out;
    00329     }
    00330
    00331   template<typename _InputIterator, typename _RandomAccessIterator,
    00332        typename _Distance>
    00333     _RandomAccessIterator
    00334     __random_sample(_InputIterator __first, _InputIterator __last,
    00335             _RandomAccessIterator __out,
    00336             const _Distance __n)
    00337     {
    00338       _Distance __m = 0;
    00339       _Distance __t = __n;
    00340       for ( ; __first != __last && __m < __n; ++__m, ++__first)
    00341     __out[__m] = *__first;
    00342
    00343       while (__first != __last)
    00344     {
    00345       ++__t;
    00346       _Distance __M = std::rand() % (__t);
    00347       if (__M < __n)
    00348         __out[__M] = *__first;
    00349       ++__first;
    00350     }
    00351       return __out + __m;
    00352     }
    00353
    00354   template<typename _InputIterator, typename _RandomAccessIterator,
    00355        typename _RandomNumberGenerator, typename _Distance>
    00356     _RandomAccessIterator
    00357     __random_sample(_InputIterator __first, _InputIterator __last,
    00358             _RandomAccessIterator __out,
    00359             _RandomNumberGenerator& __rand,
    00360             const _Distance __n)
    00361     {
    00362       // concept requirements
    00363       __glibcxx_function_requires(_UnaryFunctionConcept<
    00364         _RandomNumberGenerator, _Distance, _Distance>)
    00365
    00366       _Distance __m = 0;
    00367       _Distance __t = __n;
    00368       for ( ; __first != __last && __m < __n; ++__m, ++__first)
    00369     __out[__m] = *__first;
    00370
    00371       while (__first != __last)
    00372     {
    00373       ++__t;
    00374       _Distance __M = __rand(__t);
    00375       if (__M < __n)
    00376         __out[__M] = *__first;
    00377       ++__first;
    00378     }
    00379       return __out + __m;
    00380     }
    00381
    00382   /**
    00383    *  This is an SGI extension.
    00384    *  @ingroup SGIextensions
    00385    *  @doctodo
    00386   */
    00387   template<typename _InputIterator, typename _RandomAccessIterator>
    00388     inline _RandomAccessIterator
    00389     random_sample(_InputIterator __first, _InputIterator __last,
    00390           _RandomAccessIterator __out_first,
    00391           _RandomAccessIterator __out_last)
    00392     {
    00393       // concept requirements
    00394       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00395       __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    00396         _RandomAccessIterator>)
    00397       __glibcxx_requires_valid_range(__first, __last);
    00398       __glibcxx_requires_valid_range(__out_first, __out_last);
    00399
    00400       return __random_sample(__first, __last,
    00401                  __out_first, __out_last - __out_first);
    00402     }
    00403
    00404   /**
    00405    *  This is an SGI extension.
    00406    *  @ingroup SGIextensions
    00407    *  @doctodo
    00408   */
    00409   template<typename _InputIterator, typename _RandomAccessIterator,
    00410        typename _RandomNumberGenerator>
    00411     inline _RandomAccessIterator
    00412     random_sample(_InputIterator __first, _InputIterator __last,
    00413           _RandomAccessIterator __out_first,
    00414           _RandomAccessIterator __out_last,
    00415           _RandomNumberGenerator& __rand)
    00416     {
    00417       // concept requirements
    00418       __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
    00419       __glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
    00420         _RandomAccessIterator>)
    00421       __glibcxx_requires_valid_range(__first, __last);
    00422       __glibcxx_requires_valid_range(__out_first, __out_last);
    00423
    00424       return __random_sample(__first, __last,
    00425                  __out_first, __rand,
    00426                  __out_last - __out_first);
    00427     }
    00428
    00429   /**
    00430    *  This is an SGI extension.
    00431    *  @ingroup SGIextensions
    00432    *  @doctodo
    00433   */
    00434   template<typename _RandomAccessIterator>
    00435     inline bool
    00436     is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
    00437     {
    00438       // concept requirements
    00439       __glibcxx_function_requires(_RandomAccessIteratorConcept<
    00440                   _RandomAccessIterator>)
    00441       __glibcxx_function_requires(_LessThanComparableConcept<
    00442         typename iterator_traits<_RandomAccessIterator>::value_type>)
    00443       __glibcxx_requires_valid_range(__first, __last);
    00444
    00445       return std::__is_heap(__first, __last - __first);
    00446     }
    00447
    00448   /**
    00449    *  This is an SGI extension.
    00450    *  @ingroup SGIextensions
    00451    *  @doctodo
    00452   */
    00453   template<typename _RandomAccessIterator, typename _StrictWeakOrdering>
    00454     inline bool
    00455     is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
    00456         _StrictWeakOrdering __comp)
    00457     {
    00458       // concept requirements
    00459       __glibcxx_function_requires(_RandomAccessIteratorConcept<
    00460                   _RandomAccessIterator>)
    00461       __glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
    00462         typename iterator_traits<_RandomAccessIterator>::value_type,
    00463         typename iterator_traits<_RandomAccessIterator>::value_type>)
    00464       __glibcxx_requires_valid_range(__first, __last);
    00465
    00466       return std::__is_heap(__first, __comp, __last - __first);
    00467     }
    00468
    00469   // is_sorted, a predicated testing whether a range is sorted in
    00470   // nondescending order.  This is an extension, not part of the C++
    00471   // standard.
    00472
    00473   /**
    00474    *  This is an SGI extension.
    00475    *  @ingroup SGIextensions
    00476    *  @doctodo
    00477   */
    00478   template<typename _ForwardIterator>
    00479     bool
    00480     is_sorted(_ForwardIterator __first, _ForwardIterator __last)
    00481     {
    00482       // concept requirements
    00483       __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
    00484       __glibcxx_function_requires(_LessThanComparableConcept<
    00485         typename iterator_traits<_ForwardIterator>::value_type>)
    00486       __glibcxx_requires_valid_range(__first, __last);
    00487
    00488       if (__first == __last)
    00489     return true;
    00490
    00491       _ForwardIterator __next = __first;
    00492       for (++__next; __next != __last; __first = __next, ++__next)
    00493     if (*__next < *__first)
    00494       return false;
    00495       return true;
    00496     }
    00497
    00498   /**
    00499    *  This is an SGI extension.
    00500    *  @ingroup SGIextensions
    00501    *  @doctodo
    00502   */
    00503   template<typename _ForwardIterator, typename _StrictWeakOrdering>
    00504     bool
    00505     is_sorted(_ForwardIterator __first, _ForwardIterator __last,
    00506           _StrictWeakOrdering __comp)
    00507     {
    00508       // concept requirements
    00509       __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
    00510       __glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
    00511         typename iterator_traits<_ForwardIterator>::value_type,
    00512         typename iterator_traits<_ForwardIterator>::value_type>)
    00513       __glibcxx_requires_valid_range(__first, __last);
    00514
    00515       if (__first == __last)
    00516     return true;
    00517
    00518       _ForwardIterator __next = __first;
    00519       for (++__next; __next != __last; __first = __next, ++__next)
    00520     if (__comp(*__next, *__first))
    00521       return false;
    00522       return true;
    00523     }
    00524
    00525 _GLIBCXX_END_NAMESPACE
    00526
    00527 #endif /* _EXT_ALGORITHM */