This is utility calculator which is needed to summarize lines information. Suppose you have many lines from log file, or something like that, with structured information, which can be extracted using regular expressions. So, this calculator applies regular expression to each line, extract first match group and memorizes it. Then it gathers statistics on each unique match group value, allowing you to intersect list and count similar values.
Default list illustrates this. It have five "match one" strings, and two "match two" strings. Regular expression matches "one" and "two" and counts their occurence. Result is displayed in the table, in decreasing order.