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The header file 'is_partitioned_until.hpp' contains two variants of a single algorithm, is_partitioned_until. The algorithm tests to see if a sequence is partitioned according to a predicate; in other words, all the items in the sequence that satisfy the predicate are at the beginning of the sequence.

The routine is_partitioned_until takes a sequence and a predicate. It returns the last iterator 'it' in the sequence [begin, end) for which the is_partitioned(begin, it) is true.

is_partitioned_until come in two forms; the first one takes two iterators to define the range. The second form takes a single range parameter, and uses Boost.Range to traverse it.


The function is_partitioned_until returns the last iterator 'it' in the sequence [begin, end) for which the is_partitioned(begin, it) is true. There are two versions; one takes two iterators, and the other takes a range.

template<typename InputIterator, typename Predicate>
	InputIterator is_partitioned_until ( InputIterator first, InputIterator last, Predicate p );
template<typename Range, typename Predicate>
	typename boost::range_iterator<const Range>::type is_partitioned_until ( const Range &r, Predicate p );


Given the container c containing { 0, 1, 2, 3, 14, 15 }, then

bool isOdd ( int i ) { return i % 2 == 1; }
bool lessThan10 ( int i ) { return i < 10; }

is_partitioned_until ( c, isOdd ) --> iterator to '1'
is_partitioned_until ( c, lessThan10 ) --> end
is_partitioned_until ( c.begin (), c.end (), lessThan10 ) --> end
is_partitioned_until ( c.begin (), c.begin () + 3, lessThan10 ) --> end
is_partitioned_until ( c.end (), c.end (), isOdd ) --> end  // empty range

Iterator Requirements

is_partitioned_until works on all iterators except output iterators.


Both of the variants of is_partitioned_until run in O(N) (linear) time; that is, they compare against each element in the list once. If the sequence is found to be not partitioned at any point, the routine will terminate immediately, without examining the rest of the elements.

Exception Safety

Both of the variants of is_partitioned_until take their parameters by value or const reference, and do not depend upon any global state. Therefore, all the routines in this file provide the strong exception guarantee.