functorise NormalDelete structure so we can use share the same deletion logic and code for NormalDelete and NormalYankDelete (the latter which is not yet implemented)

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

@@ -0,0 +1,612 @@
+signature MAKE_NORMAL_DELETE =
+sig
+  val initMsgs: int * int * LineGap.t -> MailboxType.t list
+end
+
+functor MakeNormalDelete(Fn: MAKE_NORMAL_DELETE) =
+struct
+  open AppType
+  open MailboxType
+
+  fun finishAfterDeletingBuffer (app: app_type, low, buffer, time, initialMsg) =
+    let
+      val searchString = #searchString app
+      val buffer = LineGap.goToStart buffer
+      val msgs = SEARCH (buffer, searchString) :: initialMsg
+
+      val buffer = LineGap.goToIdx (low - 1111, buffer)
+      val searchList = SearchList.buildRange (buffer, searchString, low + 1111)
+
+      val buffer = LineGap.goToIdx (low, buffer)
+    in
+      NormalFinish.buildTextAndClear
+        (app, buffer, low, searchList, initialMsg, time)
+    end
+
+  fun deleteAndFinish (app: app_type, low, length, buffer, time) =
+    let
+      val buffer = LineGap.goToIdx (low + length, buffer)
+      val initialMsg = Fn.initMsgs (low, length, buffer)
+      val buffer = LineGap.delete (low, length, buffer)
+    in
+      finishAfterDeletingBuffer (app, low, buffer, time, initialMsg)
+    end
+
+  (* equivalent of vi's 'x' command **)
+  (* todo: instead of deleting in a loop, add an otherIdx accumulator instead.
+   * This will enable us to substring and yank the text that gets deleted. *)
+  fun helpRemoveChr (app: app_type, buffer, cursorIdx, count, time) =
+    if count = 0 then
+      finishAfterDeletingBuffer (app, cursorIdx, buffer, time, [])
+    else
+      let
+        val buffer = LineGap.goToIdx (cursorIdx, buffer)
+
+        (* Explanation of how Vi's 'x' command behaves:
+        * If the cursor is at the end of the file, 
+        * then it is decremented by 1.
+        * If the character after the cursor is a line break,
+        * then it is also decremented by 1.
+        * If the character before the cursor is a linee break, the cursor stays
+        * where it is.
+        * If the chracter AT the cursor is a line break and the characater
+        * AFTER the cursor is also a line break, then nothing is deleted. 
+        * Otherwise, the same cursor is returned.
+        * All decrement cases do not decrement when the cursor is 0. *)
+        val cursorIsStart = Cursor.isCursorAtStartOfLine (buffer, cursorIdx)
+        val nextIsEnd = Cursor.isNextChrEndOfLine (buffer, cursorIdx)
+      in
+        if nextIsEnd andalso cursorIsStart then
+          (* vi simply doesn't do anything on 'x' command
+          * when cursor is at start of line, and next chr is line break 
+          * so skip to end of loop by passing count of 0 *)
+          helpRemoveChr (app, buffer, cursorIdx, 0, time)
+        else if cursorIsStart then
+          helpRemoveChr (app, buffer, cursorIdx, 0, time)
+        else if nextIsEnd then
+          let
+            (* delete char at cursor and then decrement cursorIdx by 1
+            * if cursorIdx is not 0 *)
+            val searchString = #searchString app
+            val buffer = LineGap.delete (cursorIdx, 1, buffer)
+
+            val cursorIdx =
+              if
+                Cursor.isPrevChrStartOfLine (buffer, cursorIdx)
+                orelse cursorIdx = 0
+              then cursorIdx
+              else cursorIdx - 1
+          in
+            helpRemoveChr (app, buffer, cursorIdx, count - 1, time)
+          end
+        else
+          let
+            val searchString = #searchString app
+            val buffer = LineGap.delete (cursorIdx, 1, buffer)
+          in
+            helpRemoveChr (app, buffer, cursorIdx, count - 1, time)
+          end
+      end
+
+  fun removeChr (app: app_type, count, time) =
+    helpRemoveChr (app, #buffer app, #cursorIdx app, count, time)
+
+  fun helpDelete
+    (app: app_type, buffer, cursorIdx, otherIdx, count, fMove, time) =
+    (* As a small optimisation to reduce allocations, 
+    * we accumulate otherIdx by calling fMove with it and the buffer
+    * on each loop.
+    * Then, at the end of the loop, we perform the actual deletion.
+    * This is faster than performing the actual deletion on every loop
+    * because we only delete once, and avoid allocating intermediary buffers.
+    * The behaviour between the two is equivalent. *)
+    if count = 0 then
+      let
+        val low = Int.min (cursorIdx, otherIdx)
+        val high = Int.max (cursorIdx, otherIdx)
+        val high = Cursor.clipIdx (buffer, high)
+        val length = high - low
+
+        val buffer = LineGap.goToIdx (high, buffer)
+        val initialMsg = Fn.initMsgs (low, length, buffer)
+
+        val buffer = LineGap.delete (low, length, buffer)
+        val buffer = LineGap.goToStart buffer
+        val searchString = #searchString app
+        val initialMsg = SEARCH (buffer, searchString) :: initialMsg
+
+        val buffer = LineGap.goToIdx (cursorIdx - 1111, buffer)
+        val searchList =
+          SearchList.buildRange (buffer, searchString, cursorIdx + 1111)
+
+        (* If we have deleted from the buffer so that cursorIdx
+        * is no longer a valid idx,
+        * clip cursorIdx to the end. *)
+        val buffer = LineGap.goToIdx (low, buffer)
+        val cursorIdx = Cursor.clipIdx (buffer, low)
+      in
+        NormalFinish.buildTextAndClear
+          (app, buffer, cursorIdx, searchList, initialMsg, time)
+      end
+    else
+      let
+        (* get otherIdx, where cursor will want to go after motion. *)
+        val buffer = LineGap.goToIdx (otherIdx, buffer)
+        val newOtherIdx = fMove (buffer, otherIdx)
+        val newCount = if newOtherIdx = otherIdx then 0 else count - 1
+      in
+        helpDelete (app, buffer, cursorIdx, newOtherIdx, newCount, fMove, time)
+      end
+
+  fun delete (app: app_type, count, fMove, time) =
+    let val {buffer, cursorIdx, ...} = app
+    in helpDelete (app, buffer, cursorIdx, cursorIdx, count, fMove, time)
+    end
+
+  fun deleteByDfa (app: app_type, count, fMove, time) =
+    let
+      val {buffer, cursorIdx, searchString, ...} = app
+
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val otherIdx = fMove (buffer, cursorIdx, count)
+
+      val low = Int.min (cursorIdx, otherIdx)
+      val high = Int.max (cursorIdx, otherIdx)
+      val length = high - low
+    in
+      deleteAndFinish (app, low, length, buffer, time)
+    end
+
+  fun deleteToEndOfPrevWord (app: app_type, count, time) =
+    let
+      val {buffer, cursorIdx, searchString, ...} = app
+
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val low = Cursor.endOfPrevWord (buffer, cursorIdx, count)
+
+      val length = (cursorIdx + 1) - low
+    in
+      deleteAndFinish (app, low, length, buffer, time)
+    end
+
+  fun deleteToEndOfPrevWORD (app: app_type, count, time) =
+    let
+      val {buffer, cursorIdx, searchString, ...} = app
+
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val low = Cursor.endOfPrevWORD (buffer, cursorIdx, count)
+
+      val length = (cursorIdx + 1) - low
+    in
+      deleteAndFinish (app, low, length, buffer, time)
+    end
+
+  fun deleteToEndOfLine (app: app_type, time) =
+    let
+      val {buffer, cursorIdx, ...} = app
+    in
+      if Cursor.isCursorAtStartOfLine (buffer, cursorIdx) then
+        (* if we are on \n, we don't want to delete or do anything
+        * so reset the mode *)
+        NormalFinish.clearMode app
+      else
+        let
+          (* viDlr takes us to the last chr in the line 
+          * but does not delete that last chr
+          * so we call helpRemoveChr to delete that last chr. 
+          * We also rely on helpRemoveChr to handle backwards-movement logic:
+          * If cursorIdx is at \n after deletion, then stop.
+          * Else, move back one chr. *)
+          val lastChr = Cursor.viDlr (buffer, cursorIdx, 1)
+          val length = lastChr - cursorIdx
+          val buffer = LineGap.delete (cursorIdx, length, buffer)
+        in
+          helpRemoveChr (app, buffer, cursorIdx, 1, time)
+        end
+    end
+
+  fun deleteLine (app: app_type, count, time) =
+    let
+      val {buffer, cursorIdx, searchString, ...} = app
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+
+      val startIdx = Cursor.vi0 (buffer, cursorIdx)
+      val finishIdx = Cursor.viDlrForDelete (buffer, cursorIdx, count)
+
+      val length = finishIdx - startIdx
+    in
+      deleteAndFinish (app, startIdx, length, buffer, time)
+    end
+
+  fun helpDeleteLineBack (app, buffer, low, high, count, time) =
+    if count = 0 then
+      let
+        val low = Int.max (low, 0)
+        val length = high - low
+      in
+        deleteAndFinish (app, low, length, buffer, time)
+      end
+    else
+      let
+        val buffer = LineGap.goToIdx (low, buffer)
+        val low = Cursor.viH (buffer, low)
+        val buffer = LineGap.goToIdx (low, buffer)
+        val low = Cursor.vi0 (buffer, low)
+        val newCount = if low = 0 then 0 else count - 1
+      in
+        helpDeleteLineBack (app, buffer, low, high, newCount, time)
+      end
+
+  fun deleteLineBack (app: app_type, count, time) =
+    let
+      val {buffer, cursorIdx, ...} = app
+      val low = Cursor.vi0 (buffer, cursorIdx)
+      val high = Cursor.viDlr (buffer, cursorIdx, 1) + 1
+    in
+      helpDeleteLineBack (app, buffer, low, high, count, time)
+    end
+
+  fun deleteToFirstNonSpaceChr (app: app_type, time) =
+    let
+      val
+        { buffer
+        , cursorIdx
+        , windowWidth
+        , windowHeight
+        , startLine
+        , searchString
+        , ...
+        } = app
+
+      (* move LineGap and buffer to start of line *)
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val otherIdx = Cursor.vi0 (buffer, cursorIdx)
+
+      (* move cursorIdx to first character on line *)
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val otherIdx = Cursor.firstNonSpaceChr (buffer, otherIdx)
+
+      val low = Int.min (cursorIdx, otherIdx)
+      val high = Int.max (cursorIdx, otherIdx)
+      val length = high - low
+    in
+      deleteAndFinish (app, low, length, buffer, time)
+    end
+
+  fun helpDeleteToChr
+    (app: app_type, buffer, cursorIdx, otherIdx, count, fMove, fInc, chr, time) =
+    if count = 0 then
+      let
+        val low = Int.min (cursorIdx, otherIdx)
+        val high = Int.max (cursorIdx, otherIdx)
+        val length = high - low
+      in
+        deleteAndFinish (app, low, length, buffer, time)
+      end
+    else
+      let
+        val buffer = LineGap.goToIdx (otherIdx, buffer)
+        val newOtherIdx = fMove (buffer, otherIdx, chr)
+        val newCount = if newOtherIdx = otherIdx then 0 else count - 1
+        val newOtherIdx = fInc (newOtherIdx, 1)
+      in
+        helpDeleteToChr
+          ( app
+          , buffer
+          , cursorIdx
+          , newOtherIdx
+          , newCount
+          , fMove
+          , fInc
+          , chr
+          , time
+          )
+      end
+
+  fun deleteToChr (app: app_type, count, fMove, fInc, chr, time) =
+    helpDeleteToChr
+      ( app
+      , #buffer app
+      , #cursorIdx app
+      , #cursorIdx app
+      , count
+      , fMove
+      , fInc
+      , chr
+      , time
+      )
+
+  fun deleteToStart (app: app_type, time) =
+    let
+      val {cursorIdx, buffer, windowWidth, windowHeight, searchString, ...} =
+        app
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val cursorIdx = Cursor.viDlrForDelete (buffer, cursorIdx, 1)
+
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+      val initialMsg = Fn.initMsgs (0, cursorIdx, buffer)
+
+      val buffer = LineGap.delete (0, cursorIdx, buffer)
+      val buffer = LineGap.goToStart buffer
+      val initialMsg = SEARCH (buffer, #searchString app) :: initialMsg
+
+      val buffer = LineGap.goToIdx (cursorIdx - 1111, buffer)
+      val searchList =
+        SearchList.buildRange (buffer, searchString, cursorIdx + 1111)
+
+      val cursorIdx = 0
+      val startLine = 0
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+
+      val drawMsg = TextBuilder.build
+        ( startLine
+        , cursorIdx
+        , buffer
+        , windowWidth
+        , windowHeight
+        , searchList
+        , searchString
+        , initialMsg
+        )
+
+      val mode = NORMAL_MODE ""
+    in
+      NormalModeWith.bufferAndCursorIdx
+        (app, buffer, cursorIdx, mode, startLine, searchList, drawMsg, time)
+    end
+
+  fun helpDeleteToMatch (app: app_type, low, high, time) =
+    let
+      val {buffer, searchString, ...} = app
+      val buffer = LineGap.goToIdx (high, buffer)
+      val length = high - low
+      val initialMsg = Fn.initMsgs (low, length, buffer)
+
+      val buffer = LineGap.delete (low, length, buffer)
+      val buffer = LineGap.goToStart buffer
+      val initialMsg = SEARCH (buffer, searchString) :: initialMsg
+
+      val buffer = LineGap.goToIdx (low - 1111, buffer)
+      val searchList = SearchList.buildRange (buffer, searchString, low + 1111)
+
+      val buffer = LineGap.goToIdx (low, buffer)
+    in
+      NormalFinish.buildTextAndClear
+        (app, buffer, low, searchList, initialMsg, time)
+    end
+
+  fun deleteToNextMatch (app: app_type, count, time) =
+    let
+      val {cursorIdx, searchList, ...} = app
+      val newCursorIdx = SearchList.nextMatch (cursorIdx, searchList, count)
+    in
+      if newCursorIdx = ~1 orelse newCursorIdx <= cursorIdx then
+        NormalFinish.clearMode app
+      else
+        helpDeleteToMatch (app, cursorIdx, newCursorIdx, time)
+    end
+
+  fun deleteToPrevMatch (app: app_type, count, time) =
+    let
+      val {cursorIdx, searchList, ...} = app
+      val newCursorIdx = SearchList.prevMatch (cursorIdx, searchList, count)
+    in
+      if newCursorIdx = ~1 orelse newCursorIdx >= cursorIdx then
+        NormalFinish.clearMode app
+      else
+        helpDeleteToMatch (app, newCursorIdx, cursorIdx, time)
+    end
+
+  (* check if we are trying to delete from an empty buffer
+   * or a buffer which consists of only one character which is \n *)
+  fun canDeleteInsideOrAround (buffer, low, length) =
+    not (length = 1 andalso LineGap.substring (low, 1, buffer) = "\n")
+
+  fun deleteInsideWord (app: app_type, time) =
+    let
+      val {buffer, cursorIdx, searchString, ...} = app
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+
+      val low = Cursor.prevWordStrict (buffer, cursorIdx, 1)
+      val high = Cursor.endOfWordStrict (buffer, cursorIdx, 1) + 1
+
+      val buffer = LineGap.goToIdx (high, buffer)
+      val length = high - low
+    in
+      if canDeleteInsideOrAround (buffer, low, length) then
+        let
+          val buffer = LineGap.goToIdx (high, buffer)
+          val length = high - low
+          val initialMsg = Fn.initMsgs (low, length, buffer)
+
+          val buffer = LineGap.delete (low, length, buffer)
+
+          val buffer = LineGap.goToStart buffer
+          val initialMsg = SEARCH (buffer, searchString) :: initialMsg
+
+          val buffer = LineGap.goToIdx (low - 1111, buffer)
+          val searchList =
+            SearchList.buildRange (buffer, searchString, low + 1111)
+
+          val buffer = LineGap.goToIdx (low, buffer)
+        in
+          NormalFinish.buildTextAndClear
+            (app, buffer, low, searchList, initialMsg, time)
+        end
+      else
+        app
+    end
+
+  fun deleteInsideWORD (app: app_type, time) =
+    let
+      val {buffer, cursorIdx, searchString, ...} = app
+      val buffer = LineGap.goToIdx (cursorIdx, buffer)
+
+      val low = Cursor.prevWordStrict (buffer, cursorIdx, 1)
+      val high = Cursor.endOfWordStrict (buffer, cursorIdx, 1) + 1
+
+      val buffer = LineGap.goToIdx (high, buffer)
+      val length = high - low
+    in
+      if canDeleteInsideOrAround (buffer, low, length) then
+        let
+          val initialMsg = Fn.initMsgs (low, length, buffer)
+          val buffer = LineGap.delete (low, length, buffer)
+
+          val buffer = LineGap.goToStart buffer
+          val initialMsg = SEARCH (buffer, searchString) :: initialMsg
+
+          val buffer = LineGap.goToIdx (low - 1111, buffer)
+          val searchList =
+            SearchList.buildRange (buffer, searchString, low + 1111)
+
+          val buffer = LineGap.goToIdx (low, buffer)
+        in
+          NormalFinish.buildTextAndClear
+            (app, buffer, low, searchList, initialMsg, time)
+        end
+      else
+        app
+    end
+
+  fun finishAfterDeleteInside (app: app_type, origLow, high, time) =
+    if origLow = high then
+      NormalFinish.clearMode app
+    else
+      let
+        val {cursorIdx, buffer, searchString, ...} = app
+        val low = origLow + 1
+        val length = high - low
+
+        val buffer = LineGap.goToIdx (high, buffer)
+        val initialMsg = Fn.initMsgs (low, length, buffer)
+
+        val buffer = LineGap.delete (low, length, buffer)
+        val buffer = LineGap.goToStart buffer
+        val initialMsg = SEARCH (buffer, searchString) :: initialMsg
+
+        val buffer = LineGap.goToIdx (low - 1111, buffer)
+        val searchList =
+          SearchList.buildRange (buffer, searchString, low + 1111)
+
+        val buffer = LineGap.goToIdx (origLow, buffer)
+      in
+        NormalFinish.buildTextAndClear
+          (app, buffer, origLow, searchList, initialMsg, time)
+      end
+
+  fun deleteInsideChrOpen (app: app_type, chr, time) =
+    let
+      val {cursorIdx, buffer, ...} = app
+
+      val start = cursorIdx + 1
+      val buffer = LineGap.goToIdx (start, buffer)
+
+      val origLow = Cursor.toPrevChr (buffer, start, chr)
+      val buffer = LineGap.goToIdx (origLow, buffer)
+      val high = Cursor.matchPair (buffer, origLow)
+    in
+      finishAfterDeleteInside (app, origLow, high, time)
+    end
+
+  fun deleteInsideChrClose (app: app_type, chr, time) =
+    let
+      val {cursorIdx, buffer, ...} = app
+
+      val start = Int.max (cursorIdx - 1, 0)
+      val buffer = LineGap.goToIdx (start, buffer)
+
+      val high = Cursor.toNextChr (buffer, start, chr)
+      val buffer = LineGap.goToIdx (high, buffer)
+      val origLow = Cursor.matchPair (buffer, high)
+    in
+      finishAfterDeleteInside (app, origLow, high, time)
+    end
+
+  fun finishDeleteAroundChr (app, low, high, buffer, time) =
+    let
+      val length = high - low + 1
+      val buffer = LineGap.goToIdx (high, buffer)
+      val initialMsg = Fn.initMsgs (low, length, buffer)
+
+      val buffer = LineGap.delete (low, length, buffer)
+      val buffer = LineGap.goToIdx (low, buffer)
+      val low =
+        if Cursor.isCursorAtStartOfLine (buffer, low) then Int.max (low - 1, 0)
+        else low
+    in
+      finishAfterDeletingBuffer (app, low, buffer, time, initialMsg)
+    end
+
+  fun deleteAroundChrOpen (app: app_type, chr, time) =
+    let
+      val {cursorIdx, buffer, ...} = app
+
+      val start = cursorIdx + 1
+      val buffer = LineGap.goToIdx (start, buffer)
+
+      val low = Cursor.toPrevChr (buffer, start, chr)
+      val buffer = LineGap.goToIdx (low, buffer)
+      val high = Cursor.matchPair (buffer, low)
+    in
+      if low = high then NormalFinish.clearMode app
+      else finishDeleteAroundChr (app, low, high, buffer, time)
+    end
+
+  fun deleteAroundChrClose (app: app_type, chr, time) =
+    let
+      val {cursorIdx, buffer, ...} = app
+
+      val start = Int.max (cursorIdx - 1, 0)
+      val buffer = LineGap.goToIdx (start, buffer)
+
+      val high = Cursor.toNextChr (buffer, start, chr)
+      val buffer = LineGap.goToIdx (high, buffer)
+      val low = Cursor.matchPair (buffer, high)
+    in
+      if low = high then NormalFinish.clearMode app
+      else finishDeleteAroundChr (app, low, high, buffer, time)
+    end
+
+  fun deletePair (app: app_type, time) =
+    let
+      val {cursorIdx, buffer, ...} = app
+      val otherIdx = Cursor.matchPair (buffer, cursorIdx)
+    in
+      if otherIdx = cursorIdx then
+        NormalFinish.clearMode app
+      else
+        let
+          val low = Int.min (cursorIdx, otherIdx)
+          val high = Int.max (cursorIdx, otherIdx)
+          val length = high - low + 1
+
+          val buffer = LineGap.goToIdx (high, buffer)
+          val initialMsg = Fn.initMsgs (low, length, buffer)
+
+          val buffer = LineGap.delete (low, length, buffer)
+          val buffer = LineGap.goToIdx (low, buffer)
+
+          val low =
+            if Cursor.isCursorAtStartOfLine (buffer, low) then
+              (* we may have deleted the last character of this current line,
+               * and if we did, we have to move the cursor back by 1 *)
+              Int.max (low - 1, 0)
+            else
+              low
+
+          val searchString = #searchString app
+          val buffer = LineGap.goToStart buffer
+          val initialMsg = SEARCH (buffer, searchString) :: initialMsg
+
+          val buffer = LineGap.goToIdx (low - 1111, buffer)
+          val searchList =
+            SearchList.buildRange (buffer, searchString, low + 1111)
+
+          val buffer = LineGap.goToIdx (low, buffer)
+        in
+          NormalFinish.buildTextAndClear
+            (app, buffer, low, searchList, initialMsg, time)
+        end
+    end
+end

fcore/normal-mode/normal-delete.sml

@@ -1,582 +1,5 @@
 structure NormalDelete =
-struct
+  MakeNormalDelete
-  open AppType
+    (struct
-  open MailboxType
+       fun initMsgs _ = []
-
+     end)
-  fun finishAfterDeletingBuffer (app: app_type, low, buffer, time) =
-    let
-      val searchString = #searchString app
-      val buffer = LineGap.goToStart buffer
-      val initialMsg = [SEARCH (buffer, searchString)]
-
-      val buffer = LineGap.goToIdx (low - 1111, buffer)
-      val searchList = SearchList.buildRange (buffer, searchString, low + 1111)
-
-      val buffer = LineGap.goToIdx (low, buffer)
-    in
-      NormalFinish.buildTextAndClear
-        (app, buffer, low, searchList, initialMsg, time)
-    end
-
-  fun deleteAndFinish (app: app_type, low, length, buffer, time) =
-    let val buffer = LineGap.delete (low, length, buffer)
-    in finishAfterDeletingBuffer (app, low, buffer, time)
-    end
-
-  (* equivalent of vi's 'x' command **)
-  fun helpRemoveChr (app: app_type, buffer, cursorIdx, count, time) =
-    if count = 0 then
-      finishAfterDeletingBuffer (app, cursorIdx, buffer, time)
-    else
-      let
-        val buffer = LineGap.goToIdx (cursorIdx, buffer)
-
-        (* Explanation of how Vi's 'x' command behaves:
-        * If the cursor is at the end of the file, 
-        * then it is decremented by 1.
-        * If the character after the cursor is a line break,
-        * then it is also decremented by 1.
-        * If the character before the cursor is a linee break, the cursor stays
-        * where it is.
-        * If the chracter AT the cursor is a line break and the characater
-        * AFTER the cursor is also a line break, then nothing is deleted. 
-        * Otherwise, the same cursor is returned.
-        * All decrement cases do not decrement when the cursor is 0. *)
-        val cursorIsStart = Cursor.isCursorAtStartOfLine (buffer, cursorIdx)
-        val nextIsEnd = Cursor.isNextChrEndOfLine (buffer, cursorIdx)
-      in
-        if nextIsEnd andalso cursorIsStart then
-          (* vi simply doesn't do anything on 'x' command
-          * when cursor is at start of line, and next chr is line break 
-          * so skip to end of loop by passing count of 0 *)
-          helpRemoveChr (app, buffer, cursorIdx, 0, time)
-        else if cursorIsStart then
-          helpRemoveChr (app, buffer, cursorIdx, 0, time)
-        else if nextIsEnd then
-          let
-            (* delete char at cursor and then decrement cursorIdx by 1
-            * if cursorIdx is not 0 *)
-            val searchString = #searchString app
-            val buffer = LineGap.delete (cursorIdx, 1, buffer)
-
-            val cursorIdx =
-              if
-                Cursor.isPrevChrStartOfLine (buffer, cursorIdx)
-                orelse cursorIdx = 0
-              then cursorIdx
-              else cursorIdx - 1
-          in
-            helpRemoveChr (app, buffer, cursorIdx, count - 1, time)
-          end
-        else
-          let
-            val searchString = #searchString app
-            val buffer = LineGap.delete (cursorIdx, 1, buffer)
-          in
-            helpRemoveChr (app, buffer, cursorIdx, count - 1, time)
-          end
-      end
-
-  fun removeChr (app: app_type, count, time) =
-    helpRemoveChr (app, #buffer app, #cursorIdx app, count, time)
-
-  fun helpDelete
-    (app: app_type, buffer, cursorIdx, otherIdx, count, fMove, time) =
-    (* As a small optimisation to reduce allocations, 
-    * we accumulate otherIdx by calling fMove with it and the buffer
-    * on each loop.
-    * Then, at the end of the loop, we perform the actual deletion.
-    * This is faster than performing the actual deletion on every loop
-    * because we only delete once, and avoid allocating intermediary buffers.
-    * The behaviour between the two is equivalent. *)
-    if count = 0 then
-      let
-        val low = Int.min (cursorIdx, otherIdx)
-        val high = Int.max (cursorIdx, otherIdx)
-        val high = Cursor.clipIdx (buffer, high)
-        val length = high - low
-
-        val buffer = LineGap.delete (low, length, buffer)
-
-        val buffer = LineGap.goToStart buffer
-        val searchString = #searchString app
-        val initialMsg = [SEARCH (buffer, searchString)]
-
-        val buffer = LineGap.goToIdx (cursorIdx - 1111, buffer)
-        val searchList =
-          SearchList.buildRange (buffer, searchString, cursorIdx + 1111)
-
-        (* If we have deleted from the buffer so that cursorIdx
-        * is no longer a valid idx,
-        * clip cursorIdx to the end. *)
-        val buffer = LineGap.goToIdx (low, buffer)
-        val cursorIdx = Cursor.clipIdx (buffer, low)
-      in
-        NormalFinish.buildTextAndClear
-          (app, buffer, cursorIdx, searchList, initialMsg, time)
-      end
-    else
-      let
-        (* get otherIdx, where cursor will want to go after motion. *)
-        val buffer = LineGap.goToIdx (otherIdx, buffer)
-        val newOtherIdx = fMove (buffer, otherIdx)
-        val newCount = if newOtherIdx = otherIdx then 0 else count - 1
-      in
-        helpDelete (app, buffer, cursorIdx, newOtherIdx, newCount, fMove, time)
-      end
-
-  fun delete (app: app_type, count, fMove, time) =
-    let val {buffer, cursorIdx, ...} = app
-    in helpDelete (app, buffer, cursorIdx, cursorIdx, count, fMove, time)
-    end
-
-  fun deleteByDfa (app: app_type, count, fMove, time) =
-    let
-      val {buffer, cursorIdx, searchString, ...} = app
-
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-      val otherIdx = fMove (buffer, cursorIdx, count)
-
-      val low = Int.min (cursorIdx, otherIdx)
-      val high = Int.max (cursorIdx, otherIdx)
-      val length = high - low
-    in
-      deleteAndFinish (app, low, length, buffer, time)
-    end
-
-  fun deleteToEndOfPrevWord (app: app_type, count, time) =
-    let
-      val {buffer, cursorIdx, searchString, ...} = app
-
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-      val low = Cursor.endOfPrevWord (buffer, cursorIdx, count)
-
-      val length = (cursorIdx + 1) - low
-    in
-      deleteAndFinish (app, low, length, buffer, time)
-    end
-
-  fun deleteToEndOfPrevWORD (app: app_type, count, time) =
-    let
-      val {buffer, cursorIdx, searchString, ...} = app
-
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-      val low = Cursor.endOfPrevWORD (buffer, cursorIdx, count)
-
-      val length = (cursorIdx + 1) - low
-    in
-      deleteAndFinish (app, low, length, buffer, time)
-    end
-
-  fun deleteToEndOfLine (app: app_type, time) =
-    let
-      val {buffer, cursorIdx, ...} = app
-    in
-      if Cursor.isCursorAtStartOfLine (buffer, cursorIdx) then
-        (* if we are on \n, we don't want to delete or do anything
-        * so reset the mode *)
-        NormalFinish.clearMode app
-      else
-        let
-          (* viDlr takes us to the last chr in the line 
-          * but does not delete that last chr
-          * so we call helpRemoveChr to delete that last chr. 
-          * We also rely on helpRemoveChr to handle backwards-movement logic:
-          * If cursorIdx is at \n after deletion, then stop.
-          * Else, move back one chr. *)
-          val lastChr = Cursor.viDlr (buffer, cursorIdx, 1)
-          val length = lastChr - cursorIdx
-          val buffer = LineGap.delete (cursorIdx, length, buffer)
-        in
-          helpRemoveChr (app, buffer, cursorIdx, 1, time)
-        end
-    end
-
-  fun deleteLine (app: app_type, count, time) =
-    let
-      val {buffer, cursorIdx, searchString, ...} = app
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-
-      val startIdx = Cursor.vi0 (buffer, cursorIdx)
-      val finishIdx = Cursor.viDlrForDelete (buffer, cursorIdx, count)
-
-      val length = finishIdx - startIdx
-    in
-      deleteAndFinish (app, startIdx, length, buffer, time)
-    end
-
-  fun helpDeleteLineBack (app, buffer, low, high, count, time) =
-    if count = 0 then
-      let
-        val low = Int.max (low, 0)
-        val length = high - low
-      in
-        deleteAndFinish (app, low, length, buffer, time)
-      end
-    else
-      let
-        val buffer = LineGap.goToIdx (low, buffer)
-        val low = Cursor.viH (buffer, low)
-        val buffer = LineGap.goToIdx (low, buffer)
-        val low = Cursor.vi0 (buffer, low)
-        val newCount = if low = 0 then 0 else count - 1
-      in
-        helpDeleteLineBack (app, buffer, low, high, newCount, time)
-      end
-
-  fun deleteLineBack (app: app_type, count, time) =
-    let
-      val {buffer, cursorIdx, ...} = app
-      val low = Cursor.vi0 (buffer, cursorIdx)
-      val high = Cursor.viDlr (buffer, cursorIdx, 1) + 1
-    in
-      helpDeleteLineBack (app, buffer, low, high, count, time)
-    end
-
-  fun deleteToFirstNonSpaceChr (app: app_type, time) =
-    let
-      val
-        { buffer
-        , cursorIdx
-        , windowWidth
-        , windowHeight
-        , startLine
-        , searchString
-        , ...
-        } = app
-
-      (* move LineGap and buffer to start of line *)
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-      val otherIdx = Cursor.vi0 (buffer, cursorIdx)
-
-      (* move cursorIdx to first character on line *)
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-      val otherIdx = Cursor.firstNonSpaceChr (buffer, otherIdx)
-
-      val low = Int.min (cursorIdx, otherIdx)
-      val high = Int.max (cursorIdx, otherIdx)
-      val length = high - low
-    in
-      deleteAndFinish (app, low, length, buffer, time)
-    end
-
-  fun helpDeleteToChr
-    (app: app_type, buffer, cursorIdx, otherIdx, count, fMove, fInc, chr, time) =
-    if count = 0 then
-      let
-        val low = Int.min (cursorIdx, otherIdx)
-        val high = Int.max (cursorIdx, otherIdx)
-        val length = high - low
-      in
-        deleteAndFinish (app, low, length, buffer, time)
-      end
-    else
-      let
-        val buffer = LineGap.goToIdx (otherIdx, buffer)
-        val newOtherIdx = fMove (buffer, otherIdx, chr)
-        val newCount = if newOtherIdx = otherIdx then 0 else count - 1
-        val newOtherIdx = fInc (newOtherIdx, 1)
-      in
-        helpDeleteToChr
-          ( app
-          , buffer
-          , cursorIdx
-          , newOtherIdx
-          , newCount
-          , fMove
-          , fInc
-          , chr
-          , time
-          )
-      end
-
-  fun deleteToChr (app: app_type, count, fMove, fInc, chr, time) =
-    helpDeleteToChr
-      ( app
-      , #buffer app
-      , #cursorIdx app
-      , #cursorIdx app
-      , count
-      , fMove
-      , fInc
-      , chr
-      , time
-      )
-
-  fun deleteToStart (app: app_type, time) =
-    let
-      val {cursorIdx, buffer, windowWidth, windowHeight, searchString, ...} =
-        app
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-      val cursorIdx = Cursor.viDlrForDelete (buffer, cursorIdx, 1)
-
-      val buffer = LineGap.delete (0, cursorIdx, buffer)
-
-      val buffer = LineGap.goToStart buffer
-      val initialMsg = [SEARCH (buffer, #searchString app)]
-
-      val buffer = LineGap.goToIdx (cursorIdx - 1111, buffer)
-      val searchList =
-        SearchList.buildRange (buffer, searchString, cursorIdx + 1111)
-
-      val cursorIdx = 0
-      val startLine = 0
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-
-      val drawMsg = TextBuilder.build
-        ( startLine
-        , cursorIdx
-        , buffer
-        , windowWidth
-        , windowHeight
-        , searchList
-        , searchString
-        , initialMsg
-        )
-
-      val mode = NORMAL_MODE ""
-    in
-      NormalModeWith.bufferAndCursorIdx
-        (app, buffer, cursorIdx, mode, startLine, searchList, drawMsg, time)
-    end
-
-  fun helpDeleteToMatch (app: app_type, low, high, time) =
-    let
-      val {buffer, searchString, ...} = app
-      val length = high - low
-      val buffer = LineGap.delete (low, length, buffer)
-
-      val buffer = LineGap.goToStart buffer
-      val initialMsg = [SEARCH (buffer, searchString)]
-
-      val buffer = LineGap.goToIdx (low - 1111, buffer)
-      val searchList = SearchList.buildRange (buffer, searchString, low + 1111)
-
-      val buffer = LineGap.goToIdx (low, buffer)
-    in
-      NormalFinish.buildTextAndClear
-        (app, buffer, low, searchList, initialMsg, time)
-    end
-
-  fun deleteToNextMatch (app: app_type, count, time) =
-    let
-      val {cursorIdx, searchList, ...} = app
-      val newCursorIdx = SearchList.nextMatch (cursorIdx, searchList, count)
-    in
-      if newCursorIdx = ~1 orelse newCursorIdx <= cursorIdx then
-        NormalFinish.clearMode app
-      else
-        helpDeleteToMatch (app, cursorIdx, newCursorIdx, time)
-    end
-
-  fun deleteToPrevMatch (app: app_type, count, time) =
-    let
-      val {cursorIdx, searchList, ...} = app
-      val newCursorIdx = SearchList.prevMatch (cursorIdx, searchList, count)
-    in
-      if newCursorIdx = ~1 orelse newCursorIdx >= cursorIdx then
-        NormalFinish.clearMode app
-      else
-        helpDeleteToMatch (app, newCursorIdx, cursorIdx, time)
-    end
-
-  (* check if we are trying to delete from an empty buffer
-   * or a buffer which consists of only one character which is \n *)
-  fun canDeleteInsideOrAround (buffer, low, length) =
-    not (length = 1 andalso LineGap.substring (low, 1, buffer) = "\n")
-
-  fun deleteInsideWord (app: app_type, time) =
-    let
-      val {buffer, cursorIdx, searchString, ...} = app
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-
-      val low = Cursor.prevWordStrict (buffer, cursorIdx, 1)
-      val high = Cursor.endOfWordStrict (buffer, cursorIdx, 1) + 1
-
-      val buffer = LineGap.goToIdx (high, buffer)
-      val length = high - low
-    in
-      if canDeleteInsideOrAround (buffer, low, length) then
-        let
-          val length = high - low
-          val buffer = LineGap.delete (low, length, buffer)
-
-          val buffer = LineGap.goToStart buffer
-          val initialMsg = [SEARCH (buffer, searchString)]
-
-          val buffer = LineGap.goToIdx (low - 1111, buffer)
-          val searchList =
-            SearchList.buildRange (buffer, searchString, low + 1111)
-
-          val buffer = LineGap.goToIdx (low, buffer)
-        in
-          NormalFinish.buildTextAndClear
-            (app, buffer, low, searchList, initialMsg, time)
-        end
-      else
-        app
-    end
-
-  fun deleteInsideWORD (app: app_type, time) =
-    let
-      val {buffer, cursorIdx, searchString, ...} = app
-      val buffer = LineGap.goToIdx (cursorIdx, buffer)
-
-      val low = Cursor.prevWordStrict (buffer, cursorIdx, 1)
-      val high = Cursor.endOfWordStrict (buffer, cursorIdx, 1) + 1
-
-      val buffer = LineGap.goToIdx (high, buffer)
-      val length = high - low
-    in
-      if canDeleteInsideOrAround (buffer, low, length) then
-        let
-          val buffer = LineGap.delete (low, length, buffer)
-
-          val buffer = LineGap.goToStart buffer
-          val initialMsg = [SEARCH (buffer, searchString)]
-
-          val buffer = LineGap.goToIdx (low - 1111, buffer)
-          val searchList =
-            SearchList.buildRange (buffer, searchString, low + 1111)
-
-          val buffer = LineGap.goToIdx (low, buffer)
-        in
-          NormalFinish.buildTextAndClear
-            (app, buffer, low, searchList, initialMsg, time)
-        end
-      else
-        app
-    end
-
-  fun finishAfterDeleteInside (app: app_type, origLow, high, time) =
-    if origLow = high then
-      NormalFinish.clearMode app
-    else
-      let
-        val {cursorIdx, buffer, searchString, ...} = app
-        val low = origLow + 1
-        val length = high - low
-        val buffer = LineGap.delete (low, length, buffer)
-
-        val buffer = LineGap.goToStart buffer
-        val initialMsg = [SEARCH (buffer, searchString)]
-
-        val buffer = LineGap.goToIdx (low - 1111, buffer)
-        val searchList =
-          SearchList.buildRange (buffer, searchString, low + 1111)
-
-        val buffer = LineGap.goToIdx (origLow, buffer)
-      in
-        NormalFinish.buildTextAndClear
-          (app, buffer, origLow, searchList, initialMsg, time)
-      end
-
-  fun deleteInsideChrOpen (app: app_type, chr, time) =
-    let
-      val {cursorIdx, buffer, ...} = app
-
-      val start = cursorIdx + 1
-      val buffer = LineGap.goToIdx (start, buffer)
-
-      val origLow = Cursor.toPrevChr (buffer, start, chr)
-      val buffer = LineGap.goToIdx (origLow, buffer)
-      val high = Cursor.matchPair (buffer, origLow)
-    in
-      finishAfterDeleteInside (app, origLow, high, time)
-    end
-
-  fun deleteInsideChrClose (app: app_type, chr, time) =
-    let
-      val {cursorIdx, buffer, ...} = app
-
-      val start = Int.max (cursorIdx - 1, 0)
-      val buffer = LineGap.goToIdx (start, buffer)
-
-      val high = Cursor.toNextChr (buffer, start, chr)
-      val buffer = LineGap.goToIdx (high, buffer)
-      val origLow = Cursor.matchPair (buffer, high)
-    in
-      finishAfterDeleteInside (app, origLow, high, time)
-    end
-
-  fun finishDeleteAroundChr (app, low, high, buffer, time) =
-    let
-      val length = high - low + 1
-      val buffer = LineGap.delete (low, length, buffer)
-      val buffer = LineGap.goToIdx (low, buffer)
-      val low =
-        if Cursor.isCursorAtStartOfLine (buffer, low) then Int.max (low - 1, 0)
-        else low
-    in
-      finishAfterDeletingBuffer (app, low, buffer, time)
-    end
-
-  fun deleteAroundChrOpen (app: app_type, chr, time) =
-    let
-      val {cursorIdx, buffer, ...} = app
-
-      val start = cursorIdx + 1
-      val buffer = LineGap.goToIdx (start, buffer)
-
-      val low = Cursor.toPrevChr (buffer, start, chr)
-      val buffer = LineGap.goToIdx (low, buffer)
-      val high = Cursor.matchPair (buffer, low)
-    in
-      if low = high then NormalFinish.clearMode app
-      else finishDeleteAroundChr (app, low, high, buffer, time)
-    end
-
-  fun deleteAroundChrClose (app: app_type, chr, time) =
-    let
-      val {cursorIdx, buffer, ...} = app
-
-      val start = Int.max (cursorIdx - 1, 0)
-      val buffer = LineGap.goToIdx (start, buffer)
-
-      val high = Cursor.toNextChr (buffer, start, chr)
-      val buffer = LineGap.goToIdx (high, buffer)
-      val low = Cursor.matchPair (buffer, high)
-    in
-      if low = high then NormalFinish.clearMode app
-      else finishDeleteAroundChr (app, low, high, buffer, time)
-    end
-
-  fun deletePair (app: app_type, time) =
-    let
-      val {cursorIdx, buffer, ...} = app
-      val otherIdx = Cursor.matchPair (buffer, cursorIdx)
-    in
-      if otherIdx = cursorIdx then
-        NormalFinish.clearMode app
-      else
-        let
-          val low = Int.min (cursorIdx, otherIdx)
-          val high = Int.max (cursorIdx, otherIdx)
-          val length = high - low + 1
-
-          val buffer = LineGap.delete (low, length, buffer)
-          val buffer = LineGap.goToIdx (low, buffer)
-
-          val low =
-            if Cursor.isCursorAtStartOfLine (buffer, low) then
-              (* we may have deleted the last character of this current line,
-               * and if we did, we have to move the cursor back by 1 *)
-              Int.max (low - 1, 0)
-            else
-              low
-
-          val searchString = #searchString app
-          val buffer = LineGap.goToStart buffer
-          val initialMsg = [SEARCH (buffer, searchString)]
-
-          val buffer = LineGap.goToIdx (low - 1111, buffer)
-          val searchList =
-            SearchList.buildRange (buffer, searchString, low + 1111)
-
-          val buffer = LineGap.goToIdx (low, buffer)
-        in
-          NormalFinish.buildTextAndClear
-            (app, buffer, low, searchList, initialMsg, time)
-        end
-    end
-end

shf.mlb

@@ -46,6 +46,7 @@ fcore/move.sml
 
 fcore/normal-mode/normal-move.sml
 fcore/normal-mode/normal-yank.sml
+fcore/normal-mode/make-normal-delete.sml
 fcore/normal-mode/normal-delete.sml
 fcore/normal-mode/normal-mode.sml
 fcore/normal-mode/normal-search-mode.sml