code functions to build search list from a range in the buffer (not searching for every single match, but searching for visible matches on user's window)

fcore/app-update.sml

@@ -668,7 +668,7 @@ struct
         app
 
       val buffer = LineGap.delete (0, cursorIdx, buffer)
-      val (buffer, searchList) = SearchList.build (buffer, searchString)
+      val searchList = SearchList.empty
 
       val buffer = LineGap.goToEnd buffer
       val initialMsg = [SEARCH (buffer, #searchString app)]

fcore/search-list.sml

@@ -39,30 +39,20 @@ struct
         loopSearch (pos - 1, hd, absIdx - 1, tl, acc, searchString)
       end
 
-  (* Prerequisite: move buffer/LineGap to end *)
   fun search (buffer: LineGap.t, searchString) =
-    if String.size searchString = 0 then
-      empty
-    else
     let
       val {leftStrings, idx = absIdx, ...} = buffer
     in
       case leftStrings of
         hd :: tl =>
-            loopSearch
-              (String.size hd - 1, hd, absIdx - 1, tl, [], searchString)
+          loopSearch (String.size hd - 1, hd, absIdx - 1, tl, [], searchString)
       | [] => empty
     end
 
+  (* Prerequisite: move buffer/LineGap to end *)
   fun build (buffer, searchString) =
-    if String.size searchString > 0 then
-      let
-        val searchList = search (buffer, searchString)
-      in
-        searchList
-      end
-    else
-      empty
+    if String.size searchString > 0 then search (buffer, searchString)
+    else empty
 
   fun loopNextMatch (pos, searchList, count) =
     if count = 0 then
@@ -111,4 +101,87 @@ struct
       in
         loopPrevMatch (pos, searchList, count)
       end
+
+  fun rangeSearchStep (pos, hd, absIdx, tl, acc, searchPos, searchString, low) =
+    if searchPos < 0 then
+      (absIdx + 1) :: acc
+    else if absIdx < low then
+      acc
+    else if pos < 0 then
+      case tl of
+        hd :: tl =>
+          rangeSearchStep
+            ( String.size hd - 1
+            , hd
+            , absIdx
+            , tl
+            , acc
+            , searchPos
+            , searchString
+            , low
+            )
+      | [] => acc
+    else
+      let
+        val bufferChr = String.sub (hd, pos)
+        val searchChr = String.sub (searchString, searchPos)
+      in
+        if bufferChr = searchChr then
+          rangeSearchStep
+            (pos - 1, hd, absIdx - 1, tl, acc, searchPos - 1, searchString, low)
+        else
+          acc
+      end
+
+  fun loopRange (pos, hd, absIdx, tl, acc, searchString, low) =
+    if absIdx < low then
+      Vector.fromList acc
+    else if pos < 0 then
+      case tl of
+        hd :: tl =>
+          loopRange (String.size hd - 1, hd, absIdx, tl, acc, searchString, low)
+      | [] => Vector.fromList acc
+    else
+      let
+        val acc = rangeSearchStep
+          ( pos
+          , hd
+          , absIdx
+          , tl
+          , acc
+          , String.size searchString - 1
+          , searchString
+          , low
+          )
+      in
+        loopRange (pos - 1, hd, absIdx - 1, tl, acc, searchString, low)
+      end
+
+  fun searchRange (buffer: LineGap.t, searchString, low) =
+    let
+      val {rightStrings, leftStrings, idx = absIdx, ...} = buffer
+    in
+      case rightStrings of
+        hd :: _ =>
+          let
+            val pos = String.size hd - 1
+            val absIdx = absIdx + String.size hd - 1
+          in
+            loopRange (pos, hd, absIdx, leftStrings, [], searchString, low)
+          end
+      | [] =>
+          (case leftStrings of
+             hd :: tl =>
+               let
+                 val pos = String.size hd - 1
+                 val absIdx = absIdx - 1
+               in
+                 loopRange (pos, hd, absIdx, tl, [], searchString, low)
+               end
+           | [] => empty)
+    end
+
+  fun buildRange (buffer, searchString, low) =
+    if String.size searchString > 0 then searchRange (buffer, searchString, low)
+    else empty
 end

shell/shell.sml

@@ -68,9 +68,10 @@ struct
       (* todo: remove temp line below which tests search list *)
       val app =
         let
+          val buffer = #buffer app
+          val buffer = LineGap.goToEnd buffer
           val searchString = "val "
-          val (buffer, searchList) =
-            SearchList.build (#buffer app, searchString)
+          val searchList = SearchList.build (buffer, searchString)
           val buffer = LineGap.goToStart buffer
         in
           AppWith.searchList (app, searchList, buffer, searchString)