adjustments to vi-l-dfa: we should accept a single-newline as a final state, but not a double-newline

fcore/cursor-dfa/vi-l-dfa.sml

@@ -3,17 +3,20 @@ struct
   val startState: Word8.word = 0w0
   val notNewlineState: Word8.word = 0w1
   val oneNewlineState: Word8.word = 0w2
+  val twoNewlineState: Word8.word = 0w3
 
   fun makeStart i =
     if Char.chr i = #"\n" then oneNewlineState else notNewlineState
 
-  fun makeOneNewline _ = notNewlineState
+  fun makeOneNewline i =
+    if Char.chr i = #"\n" then twoNewlineState else notNewlineState
 
   val startTable = Vector.tabulate (255, makeStart)
   val notNewlineTable = startTable
   val oneNewlineTable = Vector.tabulate (255, makeOneNewline)
+  val twoNewLineTable = startTable
 
-  val tables = #[startTable, notNewlineTable, oneNewlineTable]
+  val tables = #[startTable, notNewlineTable, oneNewlineTable, twoNewLineTable]
 
   structure ViL =
     MakeNextDfaLoop
@@ -27,7 +30,9 @@ struct
                 val tables = tables
 
                 fun finish x = x
-                fun isFinal currentState = currentState = notNewlineState
+                fun isFinal currentState =
+                  currentState = notNewlineState
+                  orelse currentState = oneNewlineState
               end)
 
          val fStart = Folder.foldNext