Returns the minimal length of REGEX plus
CURRENT-MIN-REST. This is similar to REGEX-MIN-LENGTH except that it
recurses down into REGEX and sets the MIN-REST slots of REPETITION
objects.
| compute-min-rest < alternation > < t > |
| compute-min-rest < branch > < t > |
| compute-min-rest < filter > < t > |
| compute-min-rest < lookahead > < t > |
| compute-min-rest < lookbehind > < t > |
| compute-min-rest < regex > < t > |
| compute-min-rest < register > < t > |
| compute-min-rest < repetition > < t > |
| compute-min-rest < seq > < t > |
| compute-min-rest < standalone > < t > |
| compute-min-rest < str > < t > |