MB-61640: Fuzzy Dynamic Scoring

 - Allow edit distances for terms to be read

automaton.go

@@ -83,3 +83,8 @@ func (m *AlwaysMatch) Accept(int, byte) int {
 
 // creating an alwaysMatchAutomaton to avoid unnecessary repeated allocations.
 var alwaysMatchAutomaton = &AlwaysMatch{}
+
+type FuzzyAutomaton interface {
+	Automaton
+	EditDistance(int) uint8
+}

fst_iterator.go

@@ -16,8 +16,6 @@ package vellum
 
 import (
 	"bytes"
-
-	"github.com/blevesearch/vellum/levenshtein"
 )
 
 // Iterator represents a means of visiting key/value pairs in order.
@@ -219,8 +217,8 @@ OUTER:
 
 			cmp := bytes.Compare(i.keysStack, i.nextStart)
 			if cmp > 0 {
-				if dfa, ok := i.aut.(*levenshtein.DFA); ok {
-					i.keysDistance = dfa.EditDistance(autCurr)
+				if fa, ok := i.aut.(FuzzyAutomaton); ok {
+					i.keysDistance = fa.EditDistance(autCurr)
 				}
 				// in final state greater than start key
 				return nil