simplify viK and especially startViK in cursor.sml, by only checking (strIdx - 1) and (strIdx - 2)

fcore/cursor.sml

@@ -559,34 +559,14 @@ struct
 
   fun startViK (lg, strIdx, shd, cursorIdx, leftStrings, lhd, leftLines) =
     if String.sub (shd, strIdx) = #"\n" then
+      (* ? -> \n *)
       if strIdx > 0 then
         (* strIdx - 1 is in shd *)
         if String.sub (shd, strIdx - 1) = #"\n" then
-          (* strIdx - 1 is \n *)
-          if strIdx - 1 > 0 then
-            (* strIdx - 2 is in shd *)
-            if String.sub (shd, strIdx - 2) = #"\n" then
           (* \n -> \n *)
-              cursorIdx - 1
+          cursorIdx
         else
-              (* graphical-chr -> \n *)
+          (* non-graphical-chr -> \n *)
-              helpVi0 
-                (strIdx - 2, shd, cursorIdx - 2, leftStrings, leftLines)
-          else
-            (* strIdx - 2 is in leftStrings *)
-            case (leftStrings, leftLines) of
-              (lshd :: lstl, llhd :: lltl) =>
-                if String.sub (lshd, String.size lshd - 1) = #"\n" then
-                  (* \n -> \n *)
-                  cursorIdx - 1
-                else
-                  (* graphical-chr -> \n *)
-                  helpVi0 
-                    (String.size lshd - 2, lshd, cursorIdx - 2, lstl, lltl)
-            | (_, _) => 
-                cursorIdx - 1
-        else
-          (* strIdx - 1 is not \n *)
           let
             val lineColumn = getCursorColumn (lg, cursorIdx)
           in
@@ -601,49 +581,18 @@ struct
         case (leftStrings, leftLines) of
           (lshd :: lstl, llhd :: lltl) =>
             if String.sub (lshd, String.size lshd - 1) = #"\n" then
-              (* ? -> \n *)
-              if String.size lshd > 1 then
-                (* if strIdx - 2 is in lshd *)
-                if String.sub (lshd, String.size lshd - 2) = #"\n" then
               (* \n -> \n *)
-                  cursorIdx - 1
+              cursorIdx
             else
               (* graphical-chr -> \n *)
               helpVi0 
                 (String.size lshd - 2, lshd, cursorIdx - 2, lstl, lltl)
-              else
-                (* strIdx - 2 is in lstl *)
-                (case (lstl, lltl) of
-                  (stlhd :: stltl, ltlhd :: ltltl) =>
-                    if String.sub (stlhd, String.size stlhd - 1) = #"\n" then
-                      (* \n -> \n *)
-                      cursorIdx - 1
-                    else
-                      (* graphical-chr -> \n *)
-                      helpVi0 
-                        ( String.size stlhd - 2, stlhd
-                        , cursorIdx - 2, stltl, ltltl
-                        )
-                | (_, _) => 
-                    cursorIdx - 1)
-            else
-              (* does not start with \n 
-               * so start viK normally *)
-              let
-                val lineColumn = getCursorColumn (lg, cursorIdx)
-              in
-                 helpViK
-                   ( strIdx, shd, cursorIdx
-                   , lineColumn, lineColumn, false
-                   , leftStrings, lhd, leftLines
-                   )
-              end
         | (_, _) => cursorIdx
     else
       (* strIdx does not start with \n
        * so start viK normally*)
       let
-        val lineColumn = getCursorColumn (lg, cursorIdx)
+        val lineColumn = getCursorColumn (lg, cursorIdx) + 1
       in
         helpViK
           ( strIdx, shd, cursorIdx
@@ -659,30 +608,13 @@ struct
         lineGap
     in
       case (rightStrings, rightLines) of
-        (strHd :: strTl, lnHd :: lnTl) =>
+        (strHd :: _, lnHd :: _) =>
           let
             (* convert absolute cursorIdx to idx relative to hd string *)
             val strIdx = cursorIdx - bufferIdx
           in
-            if strIdx < String.size strHd then
-              (* strIdx is in this string *)
             startViK
-                (lineGap, strIdx, strHd, cursorIdx, leftStrings, lnHd, leftLines)
+              (lineGap, strIdx - 1, strHd, cursorIdx - 1, leftStrings, lnHd, leftLines)
-            else
-              (* strIdx must be in the strTl *)
-              (case (strTl, lnTl) of
-                 (nestStrHd :: nestStrTl, nestLnHd :: nestLnTl) =>
-                   let
-                     val strIdx = strIdx - String.size strHd
-                     val leftStrings = strHd :: leftStrings
-                     val leftLines = lnHd :: leftLines
-                   in
-                      startViK
-                        ( lineGap, strIdx, nestStrHd, cursorIdx
-                        , leftStrings, nestLnHd, leftLines
-                        )
-                   end
-               | (_, _) => cursorIdx)
           end
       | (_, _) => 
           (* nowhere to go rightward, so return cursorIdx *)