refactor Cursor.viH to use DFA

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

@@ -4,19 +4,30 @@ struct
   val notNewlineState: Word8.word = 0w1
   val oneNewlineState: Word8.word = 0w2
   val twoNewlineState: Word8.word = 0w3
+  val notNewlineAfterNewlineState: Word8.word = 0w4
 
   fun makeStart i =
     if Char.chr i = #"\n" then oneNewlineState else notNewlineState
 
   fun makeOneNewline i =
-    if Char.chr i = #"\n" then twoNewlineState else notNewlineState
+    if Char.chr i = #"\n" then twoNewlineState else notNewlineAfterNewlineState
+
+  fun makeTwoNeline i =
+    if Char.chr i = #"\n" then oneNewlineState else notNewlineAfterNewlineState
 
   val startTable = Vector.tabulate (255, makeStart)
   val notNewlineTable = startTable
   val oneNewlineTable = Vector.tabulate (255, makeOneNewline)
   val twoNewLineTable = startTable
+  val notNewlineAfterNewlineTable = notNewlineTable
 
-  val tables = #[startTable, notNewlineTable, oneNewlineTable, twoNewLineTable]
+  val tables =
+   #[ startTable
+    , notNewlineTable
+    , oneNewlineTable
+    , twoNewLineTable
+    , notNewlineAfterNewlineTable
+    ]
 
   fun next (currentState, chr) =
     let val table = Vector.sub (tables, Word8.toInt currentState)
@@ -38,12 +49,17 @@ struct
                val chr = String.sub (str, idx)
                val newState = next (currentState, chr)
              in
-               if newState = twoNewlineState then
+               if
+                 newState = twoNewlineState
+               then
                  if counter - 1 = ~1 then
                    absIdx - 1
                  else
                    loop (idx + 1, absIdx + 1, str, tl, startState, counter - 1)
-               else if newState = notNewlineState then
+               else if
+                 newState = notNewlineState
+                 orelse newState = notNewlineAfterNewlineState
+               then
                  if counter - 1 = ~1 then
                    absIdx
                  else
@@ -55,5 +71,43 @@ struct
          val fStart = loop
        end)
 
+  structure ViH =
+    MakePrevDfaLoop
+      (struct
+         val startState = startState
+
+         fun loop (idx, absIdx, str, tl, currentState, counter) =
+           if idx < 0 then
+             case tl of
+               str :: tl =>
+                 loop
+                   (String.size str - 1, absIdx, str, tl, currentState, counter)
+             | [] => absIdx
+           else
+             let
+               val chr = String.sub (str, idx)
+               val newState = next (currentState, chr)
+             in
+               if newState = twoNewlineState then
+                 if counter - 1 = ~1 then absIdx
+                 else loop (idx - 1, absIdx - 1, str, tl, newState, counter - 1)
+               else if newState = notNewlineState then
+                 if counter - 1 = ~1 then
+                   absIdx
+                 else
+                   loop (idx - 1, absIdx - 1, str, tl, startState, counter - 1)
+               else if newState = notNewlineAfterNewlineState then
+                 if counter - 1 <= 0 then
+                   absIdx
+                 else
+                   loop (idx - 1, absIdx - 1, str, tl, startState, counter - 1)
+               else
+                 loop (idx - 1, absIdx - 1, str, tl, newState, counter)
+             end
+
+         val fStart = loop
+       end)
+
   val next = ViL.next
+  val prev = ViH.prev
 end

fcore/cursor.sml

@@ -57,77 +57,7 @@ struct
   val viDlrForDelete = ViDlrDfa.nextForDelete
 
   val viL = ViLDfa.next
-
+  val viH = ViLDfa.prev
-  structure ViH =
-    MakeIfCharFolderPrev
-      (struct
-         type env = unit
-
-         fun helpViH (strIdx, hd, cursorIdx, leftStrings) =
-           if strIdx > 0 then
-             (* bounds check: can access prev char in hd *)
-             if String.sub (hd, strIdx - 1) = #"\n" then
-               (* prev char is line break *)
-               if strIdx - 1 > 0 then
-                 (* bounds check: can access two chars back in hd *)
-                 if String.sub (hd, strIdx - 2) = #"\n" then
-                   (* line break followed by line break
-                    * so it is fine to decrement by 1 *)
-                   cursorIdx - 1
-                 else
-                   (* non-line break followed by line break 
-                    * so we have to decrement by two,
-                    * skipping over line break *)
-                   cursorIdx - 2
-               else
-                 (* need to check two chars back in leftStrings *)
-                 (case leftStrings of
-                    lhd :: ltl =>
-                      if String.sub (lhd, String.size lhd - 1) = #"\n" then
-                        (* double line break *)
-                        cursorIdx - 1
-                      else
-                        (* non-line break precedes line break *)
-                        cursorIdx - 2
-                  | [] => cursorIdx - 1)
-             else
-               (* prev char is not line break so we can decrement by 1 *)
-               cursorIdx - 1
-           else
-             (* prev char is in leftStrings *)
-             (case leftStrings of
-                lhd :: ltl =>
-                  if String.sub (lhd, String.size lhd - 1) = #"\n" then
-                    (* one line break *)
-                    if String.size lhd > 1 then
-                      (* bounds check: prev-prev chr is in lhd *)
-                      if String.sub (lhd, String.size lhd - 2) = #"\n" then
-                        (* double line break *)
-                        cursorIdx - 1
-                      else
-                        (* non-line break precedes line break *)
-                        cursorIdx - 2
-                    else
-                      (* prev-prev chr is in ltl *)
-                      (case ltl of
-                         ltlhd :: _ =>
-                           if String.sub (ltlhd, String.size ltlhd - 1) = #"\n" then
-                             (* double line break *)
-                             cursorIdx - 1
-                           else
-                             (* non-line break precedes line break *)
-                             cursorIdx - 2
-                       | [] => cursorIdx - 1)
-                  else
-                    (* no line break *)
-                    cursorIdx - 1
-              | [] => 0)
-
-         fun fStart (strIdx, hd, _, cursorIdx, leftStrings, _, _) =
-           helpViH (strIdx, hd, cursorIdx, leftStrings)
-       end)
-
-  fun viH (lineGap, cursorIdx) = ViH.foldPrev (lineGap, cursorIdx, ())
 
   fun helpGetCursorColumn (distanceFromLine, strList, lineList) =
     case (strList, lineList) of

fcore/move.sml

@@ -42,7 +42,6 @@ struct
     end
 end
 
-structure MoveViH = MakeMove (struct val fMove = Cursor.viH end)
 structure MoveViJ = MakeMove (struct val fMove = Cursor.viJ end)
 structure MoveViK = MakeMove (struct val fMove = Cursor.viK end)
 
@@ -76,6 +75,7 @@ struct
     end
 end
 
+structure MoveViH = MakeDfaMove (struct val fMove = Cursor.viH end)
 structure MoveViL = MakeDfaMove (struct val fMove = Cursor.viL end)
 
 structure MoveToNextWord = MakeDfaMove (struct val fMove = Cursor.nextWord end)

fcore/normal-mode/make-normal-delete.sml

@@ -337,7 +337,7 @@ struct
     else
       let
         val buffer = LineGap.goToIdx (low, buffer)
-        val low = Cursor.viH (buffer, low)
+        val low = Cursor.viH (buffer, low, 1)
         val buffer = LineGap.goToIdx (low, buffer)
         val low = Cursor.vi0 (buffer, low)
         val newCount = if low = 0 then 0 else count - 1

fcore/normal-mode/normal-mode.sml

@@ -250,7 +250,7 @@ struct
     fun parseDeleteTerminal (str, count, app, chrCmd, time) =
       case chrCmd of
       (* terminal commands: require no input after *)
-        #"h" => NormalDelete.delete (app, count, Cursor.viH, time)
+        #"h" => NormalDelete.deleteByDfa (app, count, Cursor.viH, time)
       | #"l" => NormalDelete.deleteByDfa (app, count, Cursor.viL, time)
       (* vi's 'j' and 'k' commands move up or down a column
        * but 'dj' or 'dk' delete whole lines
@@ -346,7 +346,7 @@ struct
     fun parseDeleteTerminal (str, count, app, chrCmd, time) =
       case chrCmd of
       (* terminal commands: require no input after *)
-        #"h" => NormalYankDelete.delete (app, count, Cursor.viH, time)
+        #"h" => NormalYankDelete.deleteByDfa (app, count, Cursor.viH, time)
       | #"l" => NormalYankDelete.deleteByDfa (app, count, Cursor.viL, time)
       (* vi's 'j' and 'k' commands move up or down a column
        * but 'dj' or 'dk' delete whole lines