constructor() {
      this.matchIndexes = {};
      // @ts-ignore
      this.regexes = [];
      this.matchAt = 1;
      this.position = 0;
    }
Stores multiple regular expressions and allows you to quickly search for
    them all in a string simultaneously - returning the first match.  It does
    this by creating a huge (a|b|c) regex - each individual item wrapped with ()
    and joined by `|` - using match groups to track position.  When a match is
    found checking which position in the array has content allows us to figure
    out which of the original regexes / match groups triggered the match.

    The match object itself (the result of `Regex.exec`) is returned but also
    enhanced by merging in any meta-data that was registered with the regex.
    This is how we keep track of which mode matched, and what type of rule
    (`illegal`, `begin`, end, etc).