reimplement vi's 'ge' command (endOfPrevWord)

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

@@ -108,6 +108,36 @@ struct
              end
        end)
 
+  structure EndOfPrevWord =
+  MakePrevDfaLoop (
+  struct
+    val startState = startState
+
+    fun fStart (idx, absIdx, str, tl, currentState, counter) =
+      if idx < 0 then
+        case tl of
+          str :: tl => fStart (String.size str - 1, absIdx, str, tl, currentState, counter)
+        | [] => 0
+      else
+        let
+          val chr = String.sub (str, idx)
+          val newState = next (currentState, chr)
+        in
+          if newState = alphaToPunct orelse newState = punctToAlpha 
+          orelse newState = spaceToAlpha orelse newState = spaceToPunct
+          then
+            if counter - 1 = 0 then
+              absIdx
+            else
+              fStart (idx - 1, absIdx - 1, str, tl, startState, counter - 1)
+          else
+            fStart (idx - 1, absIdx - 1, str, tl, newState, counter)
+        end
+  end
+  )
+
   (* w *)
   val startOfNextWord = StartOfNextWord.next
+  (* ge *)
+  val endOfPrevWord = EndOfPrevWord.prev
 end

fcore/cursor.sml

@@ -980,40 +980,8 @@ struct
   (* equivalent of vi's 'B' command *)
   val prevWORD = ViWORDDfa.startOfCurrentWORD
 
-  fun toEndOfPrevWord (lineGap: LineGap.t, cursorIdx, fPrev) =
-    let
-      val
-        {rightStrings, rightLines, leftStrings, leftLines, idx = bufferIdx, ...} =
-        lineGap
-    in
-      case (rightStrings, rightLines) of
-        (shd :: stl, lhd :: ltl) =>
-          let
-            (* convert absolute cursorIdx to idx relative to hd string *)
-            val strIdx = cursorIdx - bufferIdx
-          in
-            if strIdx < String.size shd then
-              (* strIdx is in this string *)
-              fPrev (strIdx, shd, cursorIdx, leftStrings, leftLines)
-            else
-              (* strIdx is in tl *)
-              (case (stl, ltl) of
-                 (stlhd :: stltl, ltlhd :: ltltl) =>
-                   let
-                     val strIdx = strIdx - String.size shd
-                     val leftStrings = shd :: leftStrings
-                     val leftLines = lhd :: leftLines
-                   in
-                     fPrev (strIdx, shd, cursorIdx, leftStrings, leftLines)
-                   end
-               | (_, _) => cursorIdx)
-          end
-      | (_, _) => cursorIdx
-    end
-
   (* equivalent of vi's 'ge' command *)
-  fun endOfPrevWord (lineGap, cursorIdx) =
-    toEndOfPrevWord (lineGap, cursorIdx, helpEndOfPrevWord)
+  val endOfPrevWord = ViWordDfa.endOfPrevWord
 
   (* equivalent of vi's 'gE' command *)
   val endOfPrevWORD = ViWORDDfa.endOfPrevWORD