Boost C++ Libraries

The header file 'is_partitioned.hpp' contains two variants of a single algorithm, is_partitioned. 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 takes a sequence and a predicate. It returns true if the sequence is partitioned according to the predicate.

is_partitioned 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.

interface

The function is_partitioned returns true if the items in the sequence are separated according to their ability to satisfy the predicate. There are two versions; one takes two iterators, and the other takes a range.

template<typename InputIterator, typename Predicate>
	bool is_partitioned ( InputIterator first, InputIterator last, Predicate p );
template<typename Range, typename Predicate>
	bool is_partitioned ( const Range &r, Predicate p );

Examples

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 ( c, isOdd ) --> false
is_partitioned ( c, lessThan10 ) --> true
is_partitioned ( c.begin (), c.end (), lessThan10 ) --> true
is_partitioned ( c.begin (), c.begin () + 3, lessThan10 ) --> true
is_partitioned ( c.end (), c.end (), isOdd ) --> true  // empty range

Iterator Requirements

is_partitioned works on all iterators except output iterators.

Complexity

Both of the variants of is_partitioned 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 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.

Notes