Matching AlternativeSets with optional child expansion early on

[tsengia]

If an alternative set has a purely optional child expansion, the set will always be matched, but not matched with the correct context. The matching should match the longest possible set of words as possible before continuing.

Example grammar:

  public <command> = (hello*) | (howdy partner);

This will cause the hello* to be matched, but never match the "howdy partner".