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diff --git a/libs/algorithm/doc/ordered-hpp.qbk b/libs/algorithm/doc/ordered-hpp.qbk new file mode 100644 index 000000000..718f1f9d5 --- /dev/null +++ b/libs/algorithm/doc/ordered-hpp.qbk @@ -0,0 +1,130 @@ +[/ QuickBook Document version 1.5 ] +[section:is_sorted is_sorted ] + +[/license + +Copyright (c) 2010-2012 Marshall Clow + +Distributed under the Boost Software License, Version 1.0. +(See accompanying file LICENSE_1_0.txt or copy at +http://www.boost.org/LICENSE_1_0.txt) + +] + + +The header file `<boost/algorithm/cxx11/is_sorted.hpp>` contains functions for determining if a sequence is ordered. + +[heading is_sorted] +The function `is_sorted(sequence)` determines whether or not a sequence is completely sorted according so some criteria. If no comparison predicate is specified, then std::less_equal is used (i.e, the test is to see if the sequence is non-decreasing) + +`` +namespace boost { namespace algorithm { + template <typename Iterator, typename Pred> + bool is_sorted ( Iterator first, Iterator last, Pred p ); + + template <typename Iterator> + bool is_sorted ( Iterator first, Iterator last ); + + + template <typename Range, typename Pred> + bool is_sorted ( const Range &r, Pred p ); + + template <typename Range> + bool is_sorted ( const Range &r ); +}} +`` + +Iterator requirements: The `is_sorted` functions will work on all kinds of iterators (except output iterators). + +[heading is_sorted_until] + +If `distance(first, last) < 2`, then `is_sorted ( first, last )` returns `last`. Otherwise, it returns the last iterator i in [first,last] for which the range [first,i) is sorted. + +In short, it returns the element in the sequence that is "out of order". If the entire sequence is sorted (according to the predicate), then it will return `last`. + +`` +namespace boost { namespace algorithm { + template <typename ForwardIterator, typename Pred> + FI is_sorted_until ( ForwardIterator first, ForwardIterator last, Pred p ); + + template <typename ForwardIterator> + ForwardIterator is_sorted_until ( ForwardIterator first, ForwardIterator last ); + + + template <typename Range, typename Pred> + typename boost::range_iterator<const R>::type is_sorted_until ( const Range &r, Pred p ); + + template <typename Range> + typename boost::range_iterator<const R>::type is_sorted_until ( const Range &r ); +}} +`` + +Iterator requirements: The `is_sorted_until` functions will work on forward iterators or better. Since they have to return a place in the input sequence, input iterators will not suffice. + +Complexity: + `is_sorted_until` will make at most ['N-1] calls to the predicate (given a sequence of length ['N]). + +Examples: + +Given the sequence `{ 1, 2, 3, 4, 5, 3 }`, `is_sorted_until ( beg, end, std::less<int>())` would return an iterator pointing at the second `3`. + +Given the sequence `{ 1, 2, 3, 4, 5, 9 }`, `is_sorted_until ( beg, end, std::less<int>())` would return `end`. + + +There are also a set of "wrapper functions" for is_ordered which make it easy to see if an entire sequence is ordered. These functions return a boolean indicating success or failure rather than an iterator to where the out of order items were found. + +To test if a sequence is increasing (each element at least as large as the preceding one): +`` +namespace boost { namespace algorithm { + template <typename Iterator> + bool is_increasing ( Iterator first, Iterator last ); + + template <typename R> + bool is_increasing ( const R &range ); +}} +`` + +To test if a sequence is decreasing (each element no larger than the preceding one): + +`` +namespace boost { namespace algorithm { + template <typename Iterator> + bool is_decreasing ( Iterator first, Iterator last ); + + template <typename R> + bool is_decreasing ( const R &range ); +}} +`` + +To test if a sequence is strictly increasing (each element larger than the preceding one): +`` +namespace boost { namespace algorithm { + template <typename Iterator> + bool is_strictly_increasing ( Iterator first, Iterator last ); + + template <typename R> + bool is_strictly_increasing ( const R &range ); +}} +`` + +To test if a sequence is strictly decreasing (each element smaller than the preceding one): +`` +namespace boost { namespace algorithm { + template <typename Iterator> + bool is_strictly_decreasing ( Iterator first, Iterator last ); + + template <typename R> + bool is_strictly_decreasing ( const R &range ); +}} +`` + +Complexity: + Each of these calls is just a thin wrapper over `is_sorted`, so they have the same complexity as `is_sorted`. + +[heading Notes] + +* The routines `is_sorted` and `is_sorted_until` are part of the C++11 standard. When compiled using a C++11 implementation, the implementation from the standard library will be used. + +* `is_sorted` and `is_sorted_until` both return true for empty ranges and ranges of length one. + +[endsect] |