Partition

What is a partition?

A partition of a set is a decomposition of a set in subsets so that each element of the set is precisely in one subset. The subsets are defined in C++ by a unary predicate so that the members of the first subset fulfil the predicate. The remaining elements are in the second subset.

C++ offers a few functions for dealing with partitions. All of them need a unary predicate pre. std::partition and std::stable_partition partition a range and returns the partition point. With std::partition_point you can get the partition point of a partition. Afterwards you can check the partition with std::is_partitioned or copy it with std::partition_copy.

Checks if the range is partitioned:

bool is_partitioned(InpIt first, InpIt last, UnPre pre)
bool is_partitioned(ExePol pol, FwdIt first, FwdIt last, UnPre pre)

Partitions the range:

FwdIt partition(FwdIt first, FwdIt last, UnPre pre)
FwdIt partition(ExePol pol, FwdIt first, FwdIt last, UnPre pre...