Improves performance of pruneStates by modifying states in place

1 files changed, 7 insertions, 5 deletions

diff --git a/subex/main.go b/subex/main.go
index 635b1de..638e0f5 100644
--- a/subex/main.go
+++ b/subex/main.go
@@ -107,16 +107,18 @@ func equalStates(left SubexBranch, right SubexBranch) bool {
 
 // If two branches have the same state, only the first has a chance of being successful
 // This function removes all of the pointless execution branches to save execution time
-func pruneStates(states []SubexBranch) (newStates []SubexBranch) {
+func pruneStates(states []SubexBranch) []SubexBranch {
+	uniqueStates := 0
 	outer: for _, state := range states {
-		for _, newState := range newStates {
-			if equalStates(state, newState) {
+		for i := 0; i < uniqueStates; i++ {
+			if equalStates(state, states[i]) {
 				continue outer
 			}
 		}
-		newStates = append(newStates, state)
+		states[uniqueStates] = state
+		uniqueStates++
 	}
-	return newStates
+	return states[:uniqueStates]
 }
 
 // Run the subex transducer