[mshenfield]

Inversion of control both increases the user's power (anything that implements a certain interface can be used) and adds an extra burden. Especially here,

  match caseInsensitive contains

it takes a bit of thought to match the regex-like concept of "Case insensitive match flag" to "case insensitivity can be achieved by a transformation of the pattern and target so that case doesn't matter". Perhaps the right way to relieve this burden is to provide some simple functions that can be used for the common cases (caseInsensitive, caseSensitive) and a sensible default (caseSensitive).