namedFieldRegexMatches returns an input range iterating over all the fields (strings)
in an input range that match a regular expression. (Private function.)
This routine is used in conjunction with namedFieldGroupToRegex to find the set of
header line fields that match a field in a field-group expression. The input is a
range where the individual elements are strings, e.g. an array of strings.
The elements of the returned range are a tuple where the first element is the
one-based field number of the matching field and the second is the matched field
name. A zero-based index is returned if convertToZero is Yes.
namedFieldRegexMatches returns an input range iterating over all the fields (strings) in an input range that match a regular expression. (Private function.)
This routine is used in conjunction with namedFieldGroupToRegex to find the set of header line fields that match a field in a field-group expression. The input is a range where the individual elements are strings, e.g. an array of strings.
The elements of the returned range are a tuple where the first element is the one-based field number of the matching field and the second is the matched field name. A zero-based index is returned if convertToZero is Yes.
The regular expression must not be empty.