From 7dc94632d659e66bf75ccb24d73d2b704a8bbbd0 Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Mon, 29 Sep 2025 13:13:14 +0100
Subject: [PATCH] fix backtracking bug in 'Nfa.getMatchesInRange' (we were
 passing the wrong value instead of 'strIdx' in the recursive call to the loop
 function)

---
 fcore/search-list.sml     |  9 +++++++--
 fcore/search-list/nfa.sml | 11 ++++++-----
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/fcore/search-list.sml b/fcore/search-list.sml
index be5a443..2a0f752 100644
--- a/fcore/search-list.sml
+++ b/fcore/search-list.sml
@@ -238,9 +238,14 @@ struct
       | [] => empty
     end
 
-  fun buildRange (buffer, searchString, finish) =
+  fun buildRange (buffer, searchString, finishIdx) =
     if String.size searchString > 0 then
-      searchRange (buffer, searchString, finish)
+      let
+        val nfa = Nfa.parse searchString
+        val startIdx = #idx buffer
+      in
+        Nfa.getMatchesInRange (startIdx, finishIdx, buffer : LineGap.t, nfa)
+      end
     else
       empty
 
diff --git a/fcore/search-list/nfa.sml b/fcore/search-list/nfa.sml
index b7beade..d054df3 100644
--- a/fcore/search-list/nfa.sml
+++ b/fcore/search-list/nfa.sml
@@ -172,7 +172,7 @@ struct
               val prevIdx = absIdx - String.size prevHd
               val tl = hd :: tl
             in
-              if prevIdx < startIdx then
+              if startIdx < prevIdx then
                 (* keep backtracking *)
                 backtrackRange
                   ( prevHd
@@ -243,7 +243,7 @@ struct
             case state of
               UNTESTED =>
                 loop
-                  ( startIdx + 1
+                  ( strIdx + 1
                   , hd
                   , tl
                   , prevStrings
@@ -259,7 +259,7 @@ struct
                   val acc = PersistentVector.append (startIdx, acc)
                 in
                   loop
-                    ( startIdx + 1
+                    ( strIdx + 1
                     , hd
                     , tl
                     , prevStrings
@@ -275,7 +275,7 @@ struct
                 let
                   val prevIdx = absIdx - strIdx
                 in
-                  if prevIdx < startIdx then
+                  if startIdx < prevIdx then
                     backtrackRange
                       ( hd
                       , tl
@@ -289,7 +289,7 @@ struct
                   else
                     let
                       val strIdx = startIdx - prevIdx + 1
-                      val absIdx = absIdx + strIdx
+                      val absIdx = prevIdx + strIdx
                     in
                       loop
                         ( strIdx
@@ -474,4 +474,5 @@ struct
 
   val parse = ParseNfa.parse
   val getMatches = NfaMatch.getMatches
+  val getMatchesInRange = NfaMatch.getMatchesInRange
 end