add additional test for 'dn' motion after finding bug, fixed bug (rewrote high-level delete fundtion in persistent-vector.sml to address it), and begin adding tests for 'dN' motion

fcore/persistent-vector.sml

@@ -483,7 +483,7 @@ struct
         else
           if splitIdx > Vector.sub (sizes, Vector.length sizes - 1) then
             empty
-          else if splitIdx < Vector.sub (sizes, 0) then
+          else if splitIdx < #start (Vector.sub (items, 0)) then
             tree
           else
             let
@@ -743,13 +743,6 @@ struct
       let
         val finish = start + length
 
-        val matchBeforeStart = prevMatch (start, tree,  1)
-        val matchBeforeStart =
-          if matchBeforeStart >= start then
-            ~1
-          else
-            matchBeforeStart
-
         val matchAfterFinish = nextMatch (finish, tree, 1)
         val matchAfterFinish =
           if matchAfterFinish < finish then
@@ -757,45 +750,29 @@ struct
           else 
             matchAfterFinish
       in
-        if matchBeforeStart = ~1 andalso matchAfterFinish = ~1 then
-          empty
-        else if matchAfterFinish = ~1 then
-          (* there is no match after 'finish', so just split left. 
-           * No need to decrement or split right, 
-           * because the right vector would be empty. *)
-          splitLeft (start, tree)
-        else if matchBeforeStart = ~1 then
-          (* We don't want to use left split
-           * because there are no elements 
-           * before the deletion range's 'start'.
-           * So we make a right split and then decrement it. *)
-          let
-            val right = splitRight (finish, tree)
-          in
-            if isEmpty right then
-              empty
-            else
-              let
-                val startIdx = getStartIdx right
-                val shouldBeStartIdx = matchAfterFinish - length
-                val difference = startIdx - shouldBeStartIdx
-              in
-                if difference = 0 then
-                  right
-                else if isEmpty right then
-                  empty
-                else
-                  decrementBy (difference, right)
-              end
-          end
-        else
         let
           val left = splitLeft (start, tree)
           val right = splitRight (finish, tree)
         in
-            if isEmpty right then
+          if isEmpty left andalso isEmpty right then
+            empty
+          else if isEmpty left then
+            (* just decrement right and return it *)
+            let
+              val rightStart = getStartIdx right
+              val shouldBeStartIdx = matchAfterFinish - length
+              val difference = rightStart - shouldBeStartIdx
+            in
+              if difference = 0 then
+                right
+              else
+                decrementBy (difference, right)
+            end
+          else if isEmpty right then
+            (* return left half without doing anything *)
             left
           else
+            (* decrement right, and then merge both together *)
             let
               val leftSize = getFinishIdx left
               val rightStartRelative = getStartIdx right

fcore/search-list/search-list.sml

@@ -144,13 +144,13 @@ struct
         in
           (buffer, searchList)
         end
-    else if PersistentVector.isInRange (idx, searchList) then
-      (buffer, searchList)
     else if Dfa.isDead curState then
       if prevFinalPos = ~1 then
         (* no match found: restart search from `startPos + 1` *)
         insertUntilMatch
           (startPos + 1, buffer, searchList, dfa, 0, startPos + 1, ~1)
+      else if PersistentVector.isInRange (prevFinalPos, searchList) then
+        (buffer, searchList)
       else
         (* new match. Insert and continue *)
         let

temp.txt

@@ -1 +1,2 @@
-hellohello
+hello hello hello
+world world world

test/normal-delete-tests.sml

@@ -5824,7 +5824,6 @@ struct
           (* assert *)
           Expect.isTrue assertion
         end)
-
     , test "extends match when match should extend after deletion" (fn _ =>
         let
           (* arrange *)
@@ -5850,6 +5849,41 @@ struct
             [{start = 0, finish = 4}, {start = 6, finish = 10}]
           val expectedNewSearchList = [{start = 0, finish = 9}]
 
+          val assertion =
+            oldSearchList = expectedOldSearchList
+            andalso newSearchList = expectedNewSearchList
+        in
+          Expect.isTrue assertion
+        end)
+    , test "detects match when we delete in middle of it" (fn _ =>
+        let
+          (* arrange *)
+          val originalIdx = 1
+          val originalString = "hello hello hello\n"
+
+          val app = TestUtils.init originalString
+          val app = AppWith.idx (app, originalIdx)
+
+          val app = TestUtils.updateMany (app, "/hello")
+          val app = AppUpdate.update (app, InputMsg.KEY_ENTER, Time.now ())
+
+          (* act *)
+          val newApp = TestUtils.updateMany (app, "dn")
+
+          (* assert *)
+          val oldSearchList = #searchList app
+          val oldSearchList = PersistentVector.toList oldSearchList
+          val newSearchList = #searchList newApp
+          val newSearchList = PersistentVector.toList newSearchList
+
+          val expectedOldSearchList =
+            [ {start = 0, finish = 4}
+            , {start = 6, finish = 10}
+            , {start = 12, finish = 16}
+            ]
+          val expectedNewSearchList =
+            [{start = 1, finish = 5}, {start = 7, finish = 11}]
+
           val assertion =
             oldSearchList = expectedOldSearchList
             andalso newSearchList = expectedNewSearchList
@@ -5952,6 +5986,45 @@ struct
                (actualString = expectedString
                 andalso cursorIdx = expectedCursorIdx)
            end)
+
+    , test
+        "decrements subsequent matches in search list \
+        \when we delete prior to last match"
+        (fn _ =>
+           let
+             (* arrange *)
+             val originalIdx = 1
+             val originalString = "hello hello hello\n"
+
+             val app = TestUtils.init originalString
+             val app = AppWith.idx (app, originalIdx)
+
+             val app = TestUtils.updateMany (app, "/hello")
+             val app = AppUpdate.update (app, InputMsg.KEY_ENTER, Time.now ())
+
+             (* act *)
+             val newApp = TestUtils.updateMany (app, "dN")
+
+             (* assert *)
+             val oldSearchList = #searchList app
+             val oldSearchList = PersistentVector.toList oldSearchList
+             val newSearchList = #searchList newApp
+             val newSearchList = PersistentVector.toList newSearchList
+
+             val expectedOldSearchList =
+               [ {start = 0, finish = 4}
+               , {start = 6, finish = 10}
+               , {start = 12, finish = 16}
+               ]
+             val expectedNewSearchList =
+               [{start = 5, finish = 9}, {start = 11, finish = 15}]
+
+             val assertion =
+               oldSearchList = expectedOldSearchList
+               andalso newSearchList = expectedNewSearchList
+           in
+             Expect.isTrue assertion
+           end)
     ]
 
   val dfDelete = describe "delete motion 'df<char>'"