as far as

Short definition from Wiktionary

Conjunction

1. 1
   To the degree or extent that.
2. 2
   Used without any completion, usually to imply "to the degree or extent that ... is/are concerned".

Preposition

1. 1
   Used other than figuratively or idiomatically: see as, far, as.
2. 2
   With respect to; as relates to.