Effects: Returns the result of traits_inst.imbue(loc) where
traits_inst is a (default-initialized) instance of the template
type argument traits stored within the object.
After a call
to imbue the basic_regex object does not match any
character sequence.
Effects: Returns the result of traits_inst.getloc() where
traits_inst is a (default-initialized) instance of the template
parameter traits stored within the object.