ext/algorithm
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// Algorithm extensions -*- C++ -*-
// Copyright (C) 2001-2022 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library is free
// software; you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the
// Free Software Foundation; either version 3, or (at your option)
// any later version.
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
// Under Section 7 of GPL version 3, you are granted additional
// permissions described in the GCC Runtime Library Exception, version
// 3.1, as published by the Free Software Foundation.
// You should have received a copy of the GNU General Public License and
// a copy of the GCC Runtime Library Exception along with this program;
// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
// <http://www.gnu.org/licenses/>.
/*
*
* Copyright (c) 1994
* Hewlett-Packard Company
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Hewlett-Packard Company makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
*
* Copyright (c) 1996
* Silicon Graphics Computer Systems, Inc.
*
* Permission to use, copy, modify, distribute and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appear in all copies and
* that both that copyright notice and this permission notice appear
* in supporting documentation. Silicon Graphics makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*/
/** @file ext/algorithm
* This file is a GNU extension to the Standard C++ Library (possibly
* containing extensions from the HP/SGI STL subset).
*/
#ifndef _EXT_ALGORITHM
#define _EXT_ALGORITHM 1
#pragma GCC system_header
#include <algorithm>
namespace __gnu_cxx _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
//--------------------------------------------------
// copy_n (not part of the C++ standard)
template<typename _InputIterator, typename _Size, typename _OutputIterator>
std::pair<_InputIterator, _OutputIterator>
__copy_n(_InputIterator __first, _Size __count,
_OutputIterator __result,
std::input_iterator_tag)
{
for ( ; __count > 0; --__count)
{
*__result = *__first;
++__first;
++__result;
}
return std::pair<_InputIterator, _OutputIterator>(__first, __result);
}
template<typename _RAIterator, typename _Size, typename _OutputIterator>
inline std::pair<_RAIterator, _OutputIterator>
__copy_n(_RAIterator __first, _Size __count,
_OutputIterator __result,
std::random_access_iterator_tag)
{
_RAIterator __last = __first + __count;
return std::pair<_RAIterator, _OutputIterator>(__last, std::copy(__first,
__last,
__result));
}
/**
* @brief Copies the range [first,first+count) into [result,result+count).
* @param __first An input iterator.
* @param __count The number of elements to copy.
* @param __result An output iterator.
* @return A std::pair composed of first+count and result+count.
*
* This is an SGI extension.
* This inline function will boil down to a call to @c memmove whenever
* possible. Failing that, if random access iterators are passed, then the
* loop count will be known (and therefore a candidate for compiler
* optimizations such as unrolling).
* @ingroup SGIextensions
*/
template<typename _InputIterator, typename _Size, typename _OutputIterator>
inline std::pair<_InputIterator, _OutputIterator>
copy_n(_InputIterator __first, _Size __count, _OutputIterator __result)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename std::iterator_traits<_InputIterator>::value_type>)
return __gnu_cxx::__copy_n(__first, __count, __result,
std::__iterator_category(__first));
}
template<typename _InputIterator1, typename _InputIterator2>
int
__lexicographical_compare_3way(_InputIterator1 __first1,
_InputIterator1 __last1,
_InputIterator2 __first2,
_InputIterator2 __last2)
{
while (__first1 != __last1 && __first2 != __last2)
{
if (*__first1 < *__first2)
return -1;
if (*__first2 < *__first1)
return 1;
++__first1;
++__first2;
}
if (__first2 == __last2)
return !(__first1 == __last1);
else
return -1;
}
inline int
__lexicographical_compare_3way(const unsigned char* __first1,
const unsigned char* __last1,
const unsigned char* __first2,
const unsigned char* __last2)
{
const std::ptrdiff_t __len1 = __last1 - __first1;
const std::ptrdiff_t __len2 = __last2 - __first2;
const int __result = __builtin_memcmp(__first1, __first2,
(std::min)(__len1, __len2));
return __result != 0 ? __result
: (__len1 == __len2 ? 0 : (__len1 < __len2 ? -1 : 1));
}
inline int
__lexicographical_compare_3way(const char* __first1, const char* __last1,
const char* __first2, const char* __last2)
{
#if CHAR_MAX == SCHAR_MAX
return __lexicographical_compare_3way((const signed char*) __first1,
(const signed char*) __last1,
(const signed char*) __first2,
(const signed char*) __last2);
#else
return __lexicographical_compare_3way((const unsigned char*) __first1,
(const unsigned char*) __last1,
(const unsigned char*) __first2,
(const unsigned char*) __last2);
#endif
}
/**
* @brief @c memcmp on steroids.
* @param __first1 An input iterator.
* @param __last1 An input iterator.
* @param __first2 An input iterator.
* @param __last2 An input iterator.
* @return An int, as with @c memcmp.
*
* The return value will be less than zero if the first range is
* <em>lexigraphically less than</em> the second, greater than zero
* if the second range is <em>lexigraphically less than</em> the
* first, and zero otherwise.
* This is an SGI extension.
* @ingroup SGIextensions
*/
template<typename _InputIterator1, typename _InputIterator2>
int
lexicographical_compare_3way(_InputIterator1 __first1,
_InputIterator1 __last1,
_InputIterator2 __first2,
_InputIterator2 __last2)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator1>)
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator2>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename std::iterator_traits<_InputIterator1>::value_type>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename std::iterator_traits<_InputIterator2>::value_type>)
__glibcxx_requires_valid_range(__first1, __last1);
__glibcxx_requires_valid_range(__first2, __last2);
return __lexicographical_compare_3way(__first1, __last1, __first2,
__last2);
}
// count and count_if: this version, whose return type is void, was present
// in the HP STL, and is retained as an extension for backward compatibility.
template<typename _InputIterator, typename _Tp, typename _Size>
void
count(_InputIterator __first, _InputIterator __last,
const _Tp& __value,
_Size& __n)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_EqualityComparableConcept<
typename std::iterator_traits<_InputIterator>::value_type >)
__glibcxx_function_requires(_EqualityComparableConcept<_Tp>)
__glibcxx_requires_valid_range(__first, __last);
for ( ; __first != __last; ++__first)
if (*__first == __value)
++__n;
}
template<typename _InputIterator, typename _Predicate, typename _Size>
void
count_if(_InputIterator __first, _InputIterator __last,
_Predicate __pred,
_Size& __n)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
typename std::iterator_traits<_InputIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
for ( ; __first != __last; ++__first)
if (__pred(*__first))
++__n;
}
// random_sample and random_sample_n (extensions, not part of the standard).
/**
* This is an SGI extension.
* @ingroup SGIextensions
* @doctodo
*/
template<typename _ForwardIterator, typename _OutputIterator,
typename _Distance>
_OutputIterator
random_sample_n(_ForwardIterator __first, _ForwardIterator __last,
_OutputIterator __out, const _Distance __n)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename std::iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
_Distance __remaining = std::distance(__first, __last);
_Distance __m = (std::min)(__n, __remaining);
while (__m > 0)
{
if ((std::rand() % __remaining) < __m)
{
*__out = *__first;
++__out;
--__m;
}
--__remaining;
++__first;
}
return __out;
}
/**
* This is an SGI extension.
* @ingroup SGIextensions
* @doctodo
*/
template<typename _ForwardIterator, typename _OutputIterator,
typename _Distance, typename _RandomNumberGenerator>
_OutputIterator
random_sample_n(_ForwardIterator __first, _ForwardIterator __last,
_OutputIterator __out, const _Distance __n,
_RandomNumberGenerator& __rand)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
typename std::iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_function_requires(_UnaryFunctionConcept<
_RandomNumberGenerator, _Distance, _Distance>)
__glibcxx_requires_valid_range(__first, __last);
_Distance __remaining = std::distance(__first, __last);
_Distance __m = (std::min)(__n, __remaining);
while (__m > 0)
{
if (__rand(__remaining) < __m)
{
*__out = *__first;
++__out;
--__m;
}
--__remaining;
++__first;
}
return __out;
}
template<typename _InputIterator, typename _RandomAccessIterator,
typename _Distance>
_RandomAccessIterator
__random_sample(_InputIterator __first, _InputIterator __last,
_RandomAccessIterator __out,
const _Distance __n)
{
_Distance __m = 0;
_Distance __t = __n;
for ( ; __first != __last && __m < __n; ++__m, ++__first)
__out[__m] = *__first;
while (__first != __last)
{
++__t;
_Distance __M = std::rand() % (__t);
if (__M < __n)
__out[__M] = *__first;
++__first;
}
return __out + __m;
}
template<typename _InputIterator, typename _RandomAccessIterator,
typename _RandomNumberGenerator, typename _Distance>
_RandomAccessIterator
__random_sample(_InputIterator __first, _InputIterator __last,
_RandomAccessIterator __out,
_RandomNumberGenerator& __rand,
const _Distance __n)
{
// concept requirements
__glibcxx_function_requires(_UnaryFunctionConcept<
_RandomNumberGenerator, _Distance, _Distance>)
_Distance __m = 0;
_Distance __t = __n;
for ( ; __first != __last && __m < __n; ++__m, ++__first)
__out[__m] = *__first;
while (__first != __last)
{
++__t;
_Distance __M = __rand(__t);
if (__M < __n)
__out[__M] = *__first;
++__first;
}
return __out + __m;
}
/**
* This is an SGI extension.
* @ingroup SGIextensions
* @doctodo
*/
template<typename _InputIterator, typename _RandomAccessIterator>
inline _RandomAccessIterator
random_sample(_InputIterator __first, _InputIterator __last,
_RandomAccessIterator __out_first,
_RandomAccessIterator __out_last)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_requires_valid_range(__first, __last);
__glibcxx_requires_valid_range(__out_first, __out_last);
return __random_sample(__first, __last,
__out_first, __out_last - __out_first);
}
/**
* This is an SGI extension.
* @ingroup SGIextensions
* @doctodo
*/
template<typename _InputIterator, typename _RandomAccessIterator,
typename _RandomNumberGenerator>
inline _RandomAccessIterator
random_sample(_InputIterator __first, _InputIterator __last,
_RandomAccessIterator __out_first,
_RandomAccessIterator __out_last,
_RandomNumberGenerator& __rand)
{
// concept requirements
__glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
__glibcxx_function_requires(_Mutable_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_requires_valid_range(__first, __last);
__glibcxx_requires_valid_range(__out_first, __out_last);
return __random_sample(__first, __last,
__out_first, __rand,
__out_last - __out_first);
}
#if __cplusplus >= 201103L
using std::is_heap;
#else
/**
* This is an SGI extension.
* @ingroup SGIextensions
* @doctodo
*/
template<typename _RandomAccessIterator>
inline bool
is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
{
// concept requirements
__glibcxx_function_requires(_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename std::iterator_traits<_RandomAccessIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
return std::__is_heap(__first, __last - __first);
}
/**
* This is an SGI extension.
* @ingroup SGIextensions
* @doctodo
*/
template<typename _RandomAccessIterator, typename _StrictWeakOrdering>
inline bool
is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
_StrictWeakOrdering __comp)
{
// concept requirements
__glibcxx_function_requires(_RandomAccessIteratorConcept<
_RandomAccessIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
typename std::iterator_traits<_RandomAccessIterator>::value_type,
typename std::iterator_traits<_RandomAccessIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
return std::__is_heap(__first, __comp, __last - __first);
}
#endif
#if __cplusplus >= 201103L
using std::is_sorted;
#else
// is_sorted, a predicated testing whether a range is sorted in
// nondescending order. This is an extension, not part of the C++
// standard.
/**
* This is an SGI extension.
* @ingroup SGIextensions
* @doctodo
*/
template<typename _ForwardIterator>
bool
is_sorted(_ForwardIterator __first, _ForwardIterator __last)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_LessThanComparableConcept<
typename std::iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
if (__first == __last)
return true;
_ForwardIterator __next = __first;
for (++__next; __next != __last; __first = __next, ++__next)
if (*__next < *__first)
return false;
return true;
}
/**
* This is an SGI extension.
* @ingroup SGIextensions
* @doctodo
*/
template<typename _ForwardIterator, typename _StrictWeakOrdering>
bool
is_sorted(_ForwardIterator __first, _ForwardIterator __last,
_StrictWeakOrdering __comp)
{
// concept requirements
__glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
__glibcxx_function_requires(_BinaryPredicateConcept<_StrictWeakOrdering,
typename std::iterator_traits<_ForwardIterator>::value_type,
typename std::iterator_traits<_ForwardIterator>::value_type>)
__glibcxx_requires_valid_range(__first, __last);
if (__first == __last)
return true;
_ForwardIterator __next = __first;
for (++__next; __next != __last; __first = __next, ++__next)
if (__comp(*__next, *__first))
return false;
return true;
}
#endif // C++11
/**
* @brief Find the median of three values.
* @param __a A value.
* @param __b A value.
* @param __c A value.
* @return One of @p a, @p b or @p c.
*
* If @c {l,m,n} is some convolution of @p {a,b,c} such that @c l<=m<=n
* then the value returned will be @c m.
* This is an SGI extension.
* @ingroup SGIextensions
*/
template<typename _Tp>
const _Tp&
__median(const _Tp& __a, const _Tp& __b, const _Tp& __c)
{
// concept requirements
__glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
if (__a < __b)
if (__b < __c)
return __b;
else if (__a < __c)
return __c;
else
return __a;
else if (__a < __c)
return __a;
else if (__b < __c)
return __c;
else
return __b;
}
/**
* @brief Find the median of three values using a predicate for comparison.
* @param __a A value.
* @param __b A value.
* @param __c A value.
* @param __comp A binary predicate.
* @return One of @p a, @p b or @p c.
*
* If @c {l,m,n} is some convolution of @p {a,b,c} such that @p comp(l,m)
* and @p comp(m,n) are both true then the value returned will be @c m.
* This is an SGI extension.
* @ingroup SGIextensions
*/
template<typename _Tp, typename _Compare>
const _Tp&
__median(const _Tp& __a, const _Tp& __b, const _Tp& __c, _Compare __comp)
{
// concept requirements
__glibcxx_function_requires(_BinaryFunctionConcept<_Compare, bool,
_Tp, _Tp>)
if (__comp(__a, __b))
if (__comp(__b, __c))
return __b;
else if (__comp(__a, __c))
return __c;
else
return __a;
else if (__comp(__a, __c))
return __a;
else if (__comp(__b, __c))
return __c;
else
return __b;
}
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace
#endif /* _EXT_ALGORITHM */
__gnu_cxx::__median
const _Tp & __median(const _Tp &__a, const _Tp &__b, const _Tp &__c)
Find the median of three values.
Definition ext/algorithm:539
__gnu_cxx::random_sample_n
_OutputIterator random_sample_n(_ForwardIterator __first, _ForwardIterator __last, _OutputIterator __out, const _Distance __n)
Definition ext/algorithm:260
__gnu_cxx::random_sample
_RandomAccessIterator random_sample(_InputIterator __first, _InputIterator __last, _RandomAccessIterator __out_first, _RandomAccessIterator __out_last)
Definition ext/algorithm:381
__gnu_cxx::copy_n
std::pair< _InputIterator, _OutputIterator > copy_n(_InputIterator __first, _Size __count, _OutputIterator __result)
Copies the range [first,first+count) into [result,result+count).
Definition ext/algorithm:113
__gnu_cxx::lexicographical_compare_3way
int lexicographical_compare_3way(_InputIterator1 __first1, _InputIterator1 __last1, _InputIterator2 __first2, _InputIterator2 __last2)
memcmp on steroids.
Definition ext/algorithm:194
std::pair::pair
pair(_T1, _T2) -> pair< _T1, _T2 >
Two pairs of the same type are equal iff their members are equal.
std::min
constexpr const _Tp & min(const _Tp &, const _Tp &)
This does what you think it does.
Definition stl_algobase.h:230
std::__iterator_category
constexpr iterator_traits< _Iter >::iterator_category __iterator_category(const _Iter &)
Definition stl_iterator_base_types.h:238
std
ISO C++ entities toplevel namespace is std.
std::distance
constexpr iterator_traits< _InputIterator >::difference_type distance(_InputIterator __first, _InputIterator __last)
A generalization of pointer arithmetic.
Definition stl_iterator_base_funcs.h:147
__gnu_cxx
GNU extensions for public use.
std::iterator_traits
Traits class for iterators.
Definition stl_iterator_base_types.h:178
algorithm