match_placeholders: Match Expression Placeholders for String Interpolation
Description
Given a character string a set of expression placeholders are matched. They
are of the form ${...} or optionally $[f]{...} where f
is a valid format for sprintf.
Usage
match_placeholders(string)
Arguments
string
character: The string to be interpolated.
Value
list containing indices (regex match data) and matches,
the string representations of matched expressions.