User: Inputs which regular expression dialect (Perl, sed, etc.) to use and the
text describing the string pattern to match on and what to substitute for all
occurrences.
System: Returns two regular expressions, one for the search and one for the
replacement, and a script using the specified tool to perform the search and
replace.
User: Performs the search and replace using the script (after appropriate
editing) or uses the regular expressions in the editor or IDE.