+ if (__first == __last)
+ return false;
+ _BidirectionalIterator __i = __first;
+ ++__i;
+ if (__i == __last)
+ return false;
+ __i = __last;
+ --__i;
+
+ for(;;)
+ {
+ _BidirectionalIterator __ii = __i;
+ --__i;
+ if (*__ii < *__i)
+ {
+ _BidirectionalIterator __j = __last;
+ while (!(*--__j < *__i))
+ {}
+ std::iter_swap(__i, __j);
+ std::reverse(__ii, __last);
+ return true;
+ }
+ if (__i == __first)
+ {
+ std::reverse(__first, __last);
+ return false;
+ }
+ }
+ }
+
+ /**
+ * @brief Permute range into the previous "dictionary" ordering using
+ * comparison functor.
+ * @ingroup sorting_algorithms
+ * @param first Start of range.
+ * @param last End of range.
+ * @param comp A comparison functor.
+ * @return False if wrapped to last permutation, true otherwise.
+ *
+ * Treats all permutations of the range [first,last) as a set of
+ * "dictionary" sorted sequences ordered by @a comp. Permutes the current
+ * sequence into the previous one of this set. Returns true if there are
+ * more sequences to generate. If the sequence is the smallest of the set,
+ * the largest is generated and false returned.
+ */
+ template<typename _BidirectionalIterator, typename _Compare>
+ bool
+ prev_permutation(_BidirectionalIterator __first,
+ _BidirectionalIterator __last, _Compare __comp)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_BidirectionalIteratorConcept<
+ _BidirectionalIterator>)
+ __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
+ typename iterator_traits<_BidirectionalIterator>::value_type,
+ typename iterator_traits<_BidirectionalIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+
+ if (__first == __last)
+ return false;
+ _BidirectionalIterator __i = __first;
+ ++__i;
+ if (__i == __last)
+ return false;
+ __i = __last;
+ --__i;
+
+ for(;;)
+ {
+ _BidirectionalIterator __ii = __i;
+ --__i;
+ if (__comp(*__ii, *__i))
+ {
+ _BidirectionalIterator __j = __last;
+ while (!bool(__comp(*--__j, *__i)))
+ {}
+ std::iter_swap(__i, __j);
+ std::reverse(__ii, __last);
+ return true;
+ }
+ if (__i == __first)
+ {
+ std::reverse(__first, __last);
+ return false;
+ }
+ }
+ }
+
+ // replace
+ // replace_if
+
+ /**
+ * @brief Copy a sequence, replacing each element of one value with another
+ * value.
+ * @param first An input iterator.
+ * @param last An input iterator.
+ * @param result An output iterator.
+ * @param old_value The value to be replaced.
+ * @param new_value The replacement value.
+ * @return The end of the output sequence, @p result+(last-first).
+ *
+ * Copies each element in the input range @p [first,last) to the
+ * output range @p [result,result+(last-first)) replacing elements
+ * equal to @p old_value with @p new_value.
+ */
+ template<typename _InputIterator, typename _OutputIterator, typename _Tp>
+ _OutputIterator
+ replace_copy(_InputIterator __first, _InputIterator __last,
+ _OutputIterator __result,
+ const _Tp& __old_value, const _Tp& __new_value)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
+ typename iterator_traits<_InputIterator>::value_type>)
+ __glibcxx_function_requires(_EqualOpConcept<
+ typename iterator_traits<_InputIterator>::value_type, _Tp>)
+ __glibcxx_requires_valid_range(__first, __last);
+
+ for (; __first != __last; ++__first, ++__result)
+ if (*__first == __old_value)
+ *__result = __new_value;
+ else
+ *__result = *__first;
+ return __result;
+ }
+
+ /**
+ * @brief Copy a sequence, replacing each value for which a predicate
+ * returns true with another value.
+ * @ingroup mutating_algorithms
+ * @param first An input iterator.
+ * @param last An input iterator.
+ * @param result An output iterator.
+ * @param pred A predicate.
+ * @param new_value The replacement value.
+ * @return The end of the output sequence, @p result+(last-first).
+ *
+ * Copies each element in the range @p [first,last) to the range
+ * @p [result,result+(last-first)) replacing elements for which
+ * @p pred returns true with @p new_value.
+ */
+ template<typename _InputIterator, typename _OutputIterator,
+ typename _Predicate, typename _Tp>
+ _OutputIterator
+ replace_copy_if(_InputIterator __first, _InputIterator __last,
+ _OutputIterator __result,
+ _Predicate __pred, const _Tp& __new_value)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_function_requires(_OutputIteratorConcept<_OutputIterator,
+ typename iterator_traits<_InputIterator>::value_type>)
+ __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
+ typename iterator_traits<_InputIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+
+ for (; __first != __last; ++__first, ++__result)
+ if (__pred(*__first))
+ *__result = __new_value;
+ else
+ *__result = *__first;
+ return __result;
+ }
+
+#ifdef __GXX_EXPERIMENTAL_CXX0X__
+ /**
+ * @brief Determines whether the elements of a sequence are sorted.
+ * @ingroup sorting_algorithms
+ * @param first An iterator.
+ * @param last Another iterator.
+ * @return True if the elements are sorted, false otherwise.
+ */
+ template<typename _ForwardIterator>
+ inline bool
+ is_sorted(_ForwardIterator __first, _ForwardIterator __last)
+ { return std::is_sorted_until(__first, __last) == __last; }
+
+ /**
+ * @brief Determines whether the elements of a sequence are sorted
+ * according to a comparison functor.
+ * @ingroup sorting_algorithms
+ * @param first An iterator.
+ * @param last Another iterator.
+ * @param comp A comparison functor.
+ * @return True if the elements are sorted, false otherwise.
+ */
+ template<typename _ForwardIterator, typename _Compare>
+ inline bool
+ is_sorted(_ForwardIterator __first, _ForwardIterator __last,
+ _Compare __comp)
+ { return std::is_sorted_until(__first, __last, __comp) == __last; }
+
+ /**
+ * @brief Determines the end of a sorted sequence.
+ * @ingroup sorting_algorithms
+ * @param first An iterator.
+ * @param last Another iterator.
+ * @return An iterator pointing to the last iterator i in [first, last)
+ * for which the range [first, i) is sorted.
+ */
+ template<typename _ForwardIterator>
+ _ForwardIterator
+ is_sorted_until(_ForwardIterator __first, _ForwardIterator __last)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
+ __glibcxx_function_requires(_LessThanComparableConcept<
+ typename iterator_traits<_ForwardIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+
+ if (__first == __last)
+ return __last;
+
+ _ForwardIterator __next = __first;
+ for (++__next; __next != __last; __first = __next, ++__next)
+ if (*__next < *__first)
+ return __next;
+ return __next;
+ }
+
+ /**
+ * @brief Determines the end of a sorted sequence using comparison functor.
+ * @ingroup sorting_algorithms
+ * @param first An iterator.
+ * @param last Another iterator.
+ * @param comp A comparison functor.
+ * @return An iterator pointing to the last iterator i in [first, last)
+ * for which the range [first, i) is sorted.
+ */
+ template<typename _ForwardIterator, typename _Compare>
+ _ForwardIterator
+ is_sorted_until(_ForwardIterator __first, _ForwardIterator __last,
+ _Compare __comp)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
+ __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
+ typename iterator_traits<_ForwardIterator>::value_type,
+ typename iterator_traits<_ForwardIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+
+ if (__first == __last)
+ return __last;
+
+ _ForwardIterator __next = __first;
+ for (++__next; __next != __last; __first = __next, ++__next)
+ if (__comp(*__next, *__first))
+ return __next;
+ return __next;
+ }
+
+ /**
+ * @brief Determines min and max at once as an ordered pair.
+ * @ingroup sorting_algorithms
+ * @param a A thing of arbitrary type.
+ * @param b Another thing of arbitrary type.
+ * @return A pair(b, a) if b is smaller than a, pair(a, b) otherwise.
+ */
+ template<typename _Tp>
+ inline pair<const _Tp&, const _Tp&>
+ minmax(const _Tp& __a, const _Tp& __b)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_LessThanComparableConcept<_Tp>)
+
+ return __b < __a ? pair<const _Tp&, const _Tp&>(__b, __a)
+ : pair<const _Tp&, const _Tp&>(__a, __b);
+ }
+
+ /**
+ * @brief Determines min and max at once as an ordered pair.
+ * @ingroup sorting_algorithms
+ * @param a A thing of arbitrary type.
+ * @param b Another thing of arbitrary type.
+ * @param comp A @link comparison_functor comparison functor@endlink.
+ * @return A pair(b, a) if b is smaller than a, pair(a, b) otherwise.
+ */
+ template<typename _Tp, typename _Compare>
+ inline pair<const _Tp&, const _Tp&>
+ minmax(const _Tp& __a, const _Tp& __b, _Compare __comp)
+ {
+ return __comp(__b, __a) ? pair<const _Tp&, const _Tp&>(__b, __a)
+ : pair<const _Tp&, const _Tp&>(__a, __b);
+ }
+
+ /**
+ * @brief Return a pair of iterators pointing to the minimum and maximum
+ * elements in a range.
+ * @ingroup sorting_algorithms
+ * @param first Start of range.
+ * @param last End of range.
+ * @return make_pair(m, M), where m is the first iterator i in
+ * [first, last) such that no other element in the range is
+ * smaller, and where M is the last iterator i in [first, last)
+ * such that no other element in the range is larger.
+ */
+ template<typename _ForwardIterator>
+ pair<_ForwardIterator, _ForwardIterator>
+ minmax_element(_ForwardIterator __first, _ForwardIterator __last)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
+ __glibcxx_function_requires(_LessThanComparableConcept<
+ typename iterator_traits<_ForwardIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+
+ _ForwardIterator __next = __first;
+ if (__first == __last
+ || ++__next == __last)
+ return std::make_pair(__first, __first);
+
+ _ForwardIterator __min, __max;
+ if (*__next < *__first)
+ {
+ __min = __next;
+ __max = __first;
+ }
+ else
+ {
+ __min = __first;
+ __max = __next;
+ }
+
+ __first = __next;
+ ++__first;
+
+ while (__first != __last)
+ {
+ __next = __first;
+ if (++__next == __last)
+ {
+ if (*__first < *__min)
+ __min = __first;
+ else if (!(*__first < *__max))
+ __max = __first;
+ break;
+ }
+
+ if (*__next < *__first)
+ {
+ if (*__next < *__min)
+ __min = __next;
+ if (!(*__first < *__max))
+ __max = __first;
+ }
+ else
+ {
+ if (*__first < *__min)
+ __min = __first;
+ if (!(*__next < *__max))
+ __max = __next;
+ }
+
+ __first = __next;
+ ++__first;
+ }
+
+ return std::make_pair(__min, __max);
+ }
+
+ /**
+ * @brief Return a pair of iterators pointing to the minimum and maximum
+ * elements in a range.
+ * @ingroup sorting_algorithms
+ * @param first Start of range.
+ * @param last End of range.
+ * @param comp Comparison functor.
+ * @return make_pair(m, M), where m is the first iterator i in
+ * [first, last) such that no other element in the range is
+ * smaller, and where M is the last iterator i in [first, last)
+ * such that no other element in the range is larger.
+ */
+ template<typename _ForwardIterator, typename _Compare>
+ pair<_ForwardIterator, _ForwardIterator>
+ minmax_element(_ForwardIterator __first, _ForwardIterator __last,
+ _Compare __comp)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
+ __glibcxx_function_requires(_BinaryPredicateConcept<_Compare,
+ typename iterator_traits<_ForwardIterator>::value_type,
+ typename iterator_traits<_ForwardIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+
+ _ForwardIterator __next = __first;
+ if (__first == __last
+ || ++__next == __last)
+ return std::make_pair(__first, __first);
+
+ _ForwardIterator __min, __max;
+ if (__comp(*__next, *__first))
+ {
+ __min = __next;
+ __max = __first;
+ }
+ else
+ {
+ __min = __first;
+ __max = __next;
+ }
+
+ __first = __next;
+ ++__first;
+
+ while (__first != __last)
+ {
+ __next = __first;
+ if (++__next == __last)
+ {
+ if (__comp(*__first, *__min))
+ __min = __first;
+ else if (!__comp(*__first, *__max))
+ __max = __first;
+ break;
+ }
+
+ if (__comp(*__next, *__first))
+ {
+ if (__comp(*__next, *__min))
+ __min = __next;
+ if (!__comp(*__first, *__max))
+ __max = __first;
+ }
+ else
+ {
+ if (__comp(*__first, *__min))
+ __min = __first;
+ if (!__comp(*__next, *__max))
+ __max = __next;
+ }
+
+ __first = __next;
+ ++__first;
+ }
+
+ return std::make_pair(__min, __max);
+ }
+
+ // N2722 + fixes.
+ template<typename _Tp>
+ inline _Tp
+ min(initializer_list<_Tp> __l)
+ { return *std::min_element(__l.begin(), __l.end()); }
+
+ template<typename _Tp, typename _Compare>
+ inline _Tp
+ min(initializer_list<_Tp> __l, _Compare __comp)
+ { return *std::min_element(__l.begin(), __l.end(), __comp); }
+
+ template<typename _Tp>
+ inline _Tp
+ max(initializer_list<_Tp> __l)
+ { return *std::max_element(__l.begin(), __l.end()); }
+
+ template<typename _Tp, typename _Compare>
+ inline _Tp
+ max(initializer_list<_Tp> __l, _Compare __comp)
+ { return *std::max_element(__l.begin(), __l.end(), __comp); }
+
+ template<typename _Tp>
+ inline pair<_Tp, _Tp>
+ minmax(initializer_list<_Tp> __l)
+ {
+ pair<const _Tp*, const _Tp*> __p =
+ std::minmax_element(__l.begin(), __l.end());
+ return std::make_pair(*__p.first, *__p.second);
+ }
+
+ template<typename _Tp, typename _Compare>
+ inline pair<_Tp, _Tp>
+ minmax(initializer_list<_Tp> __l, _Compare __comp)
+ {
+ pair<const _Tp*, const _Tp*> __p =
+ std::minmax_element(__l.begin(), __l.end(), __comp);
+ return std::make_pair(*__p.first, *__p.second);
+ }
+#endif // __GXX_EXPERIMENTAL_CXX0X__
+
+_GLIBCXX_END_NAMESPACE
+
+_GLIBCXX_BEGIN_NESTED_NAMESPACE(std, _GLIBCXX_STD_P)
+
+ /**
+ * @brief Apply a function to every element of a sequence.
+ * @ingroup non_mutating_algorithms
+ * @param first An input iterator.
+ * @param last An input iterator.
+ * @param f A unary function object.
+ * @return @p f.
+ *
+ * Applies the function object @p f to each element in the range
+ * @p [first,last). @p f must not modify the order of the sequence.
+ * If @p f has a return value it is ignored.
+ */
+ template<typename _InputIterator, typename _Function>
+ _Function
+ for_each(_InputIterator __first, _InputIterator __last, _Function __f)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_requires_valid_range(__first, __last);
+ for (; __first != __last; ++__first)
+ __f(*__first);
+ return __f;
+ }
+
+ /**
+ * @brief Find the first occurrence of a value in a sequence.
+ * @ingroup non_mutating_algorithms
+ * @param first An input iterator.
+ * @param last An input iterator.
+ * @param val The value to find.
+ * @return The first iterator @c i in the range @p [first,last)
+ * such that @c *i == @p val, or @p last if no such iterator exists.
+ */
+ template<typename _InputIterator, typename _Tp>
+ inline _InputIterator
+ find(_InputIterator __first, _InputIterator __last,
+ const _Tp& __val)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_function_requires(_EqualOpConcept<
+ typename iterator_traits<_InputIterator>::value_type, _Tp>)
+ __glibcxx_requires_valid_range(__first, __last);
+ return std::__find(__first, __last, __val,
+ std::__iterator_category(__first));
+ }
+
+ /**
+ * @brief Find the first element in a sequence for which a
+ * predicate is true.
+ * @ingroup non_mutating_algorithms
+ * @param first An input iterator.
+ * @param last An input iterator.
+ * @param pred A predicate.
+ * @return The first iterator @c i in the range @p [first,last)
+ * such that @p pred(*i) is true, or @p last if no such iterator exists.
+ */
+ template<typename _InputIterator, typename _Predicate>
+ inline _InputIterator
+ find_if(_InputIterator __first, _InputIterator __last,
+ _Predicate __pred)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
+ typename iterator_traits<_InputIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+ return std::__find_if(__first, __last, __pred,
+ std::__iterator_category(__first));
+ }
+
+ /**
+ * @brief Find element from a set in a sequence.
+ * @ingroup non_mutating_algorithms
+ * @param first1 Start of range to search.
+ * @param last1 End of range to search.
+ * @param first2 Start of match candidates.
+ * @param last2 End of match candidates.
+ * @return The first iterator @c i in the range
+ * @p [first1,last1) such that @c *i == @p *(i2) such that i2 is an
+ * iterator in [first2,last2), or @p last1 if no such iterator exists.
+ *
+ * Searches the range @p [first1,last1) for an element that is equal to
+ * some element in the range [first2,last2). If found, returns an iterator
+ * in the range [first1,last1), otherwise returns @p last1.
+ */
+ template<typename _InputIterator, typename _ForwardIterator>
+ _InputIterator
+ find_first_of(_InputIterator __first1, _InputIterator __last1,
+ _ForwardIterator __first2, _ForwardIterator __last2)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
+ __glibcxx_function_requires(_EqualOpConcept<
+ typename iterator_traits<_InputIterator>::value_type,
+ typename iterator_traits<_ForwardIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first1, __last1);
+ __glibcxx_requires_valid_range(__first2, __last2);
+
+ for (; __first1 != __last1; ++__first1)
+ for (_ForwardIterator __iter = __first2; __iter != __last2; ++__iter)
+ if (*__first1 == *__iter)
+ return __first1;
+ return __last1;
+ }
+
+ /**
+ * @brief Find element from a set in a sequence using a predicate.
+ * @ingroup non_mutating_algorithms
+ * @param first1 Start of range to search.
+ * @param last1 End of range to search.
+ * @param first2 Start of match candidates.
+ * @param last2 End of match candidates.
+ * @param comp Predicate to use.
+ * @return The first iterator @c i in the range
+ * @p [first1,last1) such that @c comp(*i, @p *(i2)) is true and i2 is an
+ * iterator in [first2,last2), or @p last1 if no such iterator exists.
+ *
+
+ * Searches the range @p [first1,last1) for an element that is
+ * equal to some element in the range [first2,last2). If found,
+ * returns an iterator in the range [first1,last1), otherwise
+ * returns @p last1.
+ */
+ template<typename _InputIterator, typename _ForwardIterator,
+ typename _BinaryPredicate>
+ _InputIterator
+ find_first_of(_InputIterator __first1, _InputIterator __last1,
+ _ForwardIterator __first2, _ForwardIterator __last2,
+ _BinaryPredicate __comp)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
+ __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
+ typename iterator_traits<_InputIterator>::value_type,
+ typename iterator_traits<_ForwardIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first1, __last1);
+ __glibcxx_requires_valid_range(__first2, __last2);
+
+ for (; __first1 != __last1; ++__first1)
+ for (_ForwardIterator __iter = __first2; __iter != __last2; ++__iter)
+ if (__comp(*__first1, *__iter))
+ return __first1;
+ return __last1;
+ }
+
+ /**
+ * @brief Find two adjacent values in a sequence that are equal.
+ * @ingroup non_mutating_algorithms
+ * @param first A forward iterator.
+ * @param last A forward iterator.
+ * @return The first iterator @c i such that @c i and @c i+1 are both
+ * valid iterators in @p [first,last) and such that @c *i == @c *(i+1),
+ * or @p last if no such iterator exists.
+ */
+ template<typename _ForwardIterator>
+ _ForwardIterator
+ adjacent_find(_ForwardIterator __first, _ForwardIterator __last)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
+ __glibcxx_function_requires(_EqualityComparableConcept<
+ typename iterator_traits<_ForwardIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+ if (__first == __last)
+ return __last;
+ _ForwardIterator __next = __first;
+ while(++__next != __last)
+ {
+ if (*__first == *__next)
+ return __first;
+ __first = __next;
+ }
+ return __last;
+ }
+
+ /**
+ * @brief Find two adjacent values in a sequence using a predicate.
+ * @ingroup non_mutating_algorithms
+ * @param first A forward iterator.
+ * @param last A forward iterator.
+ * @param binary_pred A binary predicate.
+ * @return The first iterator @c i such that @c i and @c i+1 are both
+ * valid iterators in @p [first,last) and such that
+ * @p binary_pred(*i,*(i+1)) is true, or @p last if no such iterator
+ * exists.
+ */
+ template<typename _ForwardIterator, typename _BinaryPredicate>
+ _ForwardIterator
+ adjacent_find(_ForwardIterator __first, _ForwardIterator __last,
+ _BinaryPredicate __binary_pred)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator>)
+ __glibcxx_function_requires(_BinaryPredicateConcept<_BinaryPredicate,
+ typename iterator_traits<_ForwardIterator>::value_type,
+ typename iterator_traits<_ForwardIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+ if (__first == __last)
+ return __last;
+ _ForwardIterator __next = __first;
+ while(++__next != __last)
+ {
+ if (__binary_pred(*__first, *__next))
+ return __first;
+ __first = __next;
+ }
+ return __last;
+ }
+
+ /**
+ * @brief Count the number of copies of a value in a sequence.
+ * @ingroup non_mutating_algorithms
+ * @param first An input iterator.
+ * @param last An input iterator.
+ * @param value The value to be counted.
+ * @return The number of iterators @c i in the range @p [first,last)
+ * for which @c *i == @p value
+ */
+ template<typename _InputIterator, typename _Tp>
+ typename iterator_traits<_InputIterator>::difference_type
+ count(_InputIterator __first, _InputIterator __last, const _Tp& __value)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_function_requires(_EqualOpConcept<
+ typename iterator_traits<_InputIterator>::value_type, _Tp>)
+ __glibcxx_requires_valid_range(__first, __last);
+ typename iterator_traits<_InputIterator>::difference_type __n = 0;
+ for (; __first != __last; ++__first)
+ if (*__first == __value)
+ ++__n;
+ return __n;
+ }
+
+ /**
+ * @brief Count the elements of a sequence for which a predicate is true.
+ * @ingroup non_mutating_algorithms
+ * @param first An input iterator.
+ * @param last An input iterator.
+ * @param pred A predicate.
+ * @return The number of iterators @c i in the range @p [first,last)
+ * for which @p pred(*i) is true.
+ */
+ template<typename _InputIterator, typename _Predicate>
+ typename iterator_traits<_InputIterator>::difference_type
+ count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_InputIteratorConcept<_InputIterator>)
+ __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
+ typename iterator_traits<_InputIterator>::value_type>)
+ __glibcxx_requires_valid_range(__first, __last);
+ typename iterator_traits<_InputIterator>::difference_type __n = 0;
+ for (; __first != __last; ++__first)
+ if (__pred(*__first))
+ ++__n;
+ return __n;
+ }
+
+ /**
+ * @brief Search a sequence for a matching sub-sequence.
+ * @ingroup non_mutating_algorithms
+ * @param first1 A forward iterator.
+ * @param last1 A forward iterator.
+ * @param first2 A forward iterator.
+ * @param last2 A forward iterator.
+ * @return The first iterator @c i in the range
+ * @p [first1,last1-(last2-first2)) such that @c *(i+N) == @p *(first2+N)
+ * for each @c N in the range @p [0,last2-first2), or @p last1 if no
+ * such iterator exists.
+ *
+ * Searches the range @p [first1,last1) for a sub-sequence that compares
+ * equal value-by-value with the sequence given by @p [first2,last2) and
+ * returns an iterator to the first element of the sub-sequence, or
+ * @p last1 if the sub-sequence is not found.
+ *
+ * Because the sub-sequence must lie completely within the range
+ * @p [first1,last1) it must start at a position less than
+ * @p last1-(last2-first2) where @p last2-first2 is the length of the
+ * sub-sequence.
+ * This means that the returned iterator @c i will be in the range
+ * @p [first1,last1-(last2-first2))
+ */
+ template<typename _ForwardIterator1, typename _ForwardIterator2>
+ _ForwardIterator1
+ search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
+ _ForwardIterator2 __first2, _ForwardIterator2 __last2)
+ {
+ // concept requirements
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator1>)
+ __glibcxx_function_requires(_ForwardIteratorConcept<_ForwardIterator2>)
+ __glibcxx_function_requires(_EqualOpConcept<
+ typename iterator_traits<_ForwardIterator1>::value_type,
+ typename iterator_traits<_ForwardIterator2>::value_type>)
+ __glibcxx_requires_valid_range(__first1, __last1);
+ __glibcxx_requires_valid_range(__first2, __last2);
+
+ // Test for empty ranges
+ if (__first1 == __last1 || __first2 == __last2)
+ return __first1;
+
+ // Test for a pattern of length 1.
+ _ForwardIterator2 __p1(__first2);
+ if (++__p1 == __last2)
+ return _GLIBCXX_STD_P::find(__first1, __last1, *__first2);
+
+ // General case.
+ _ForwardIterator2 __p;
+ _ForwardIterator1 __current = __first1;
+
+ for (;;)
+ {
+ __first1 = _GLIBCXX_STD_P::find(__first1, __last1, *__first2);
+ if (__first1 == __last1)
+ return __last1;
+
+ __p = __p1;
+ __current = __first1;
+ if (++__current == __last1)
+ return __last1;
+
+ while (*__current == *__p)
+ {
+ if (++__p == __last2)
+ return __first1;
+ if (++__current == __last1)
+ return __last1;
+ }