From d6d518b5b4d7d7cb1ed1d3fca0bb1cbf0e52c5b6 Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Tue, 21 May 2024 17:21:09 +0100
Subject: [PATCH] fix correctness error in tiny_rope23.sml's ins function (to
 do with traverseing down the N3 case)

---
 .gitignore      | 10 ++++++++++
 bench.mlb       | 12 ++++++++++++
 tiny_rope.sml   | 14 ++++++++++----
 tiny_rope23.sml | 14 ++++++++++++--
 utils.sml       | 37 ++++++++++++++++++++++++++-----------
 5 files changed, 70 insertions(+), 17 deletions(-)

diff --git a/.gitignore b/.gitignore
index 625cbc1..68d400c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,6 +1,16 @@
 /bench
 /bench.du
 /bench.ud
+/bench23
 /examples
 /examples.du
 /examples.ud
+
+/svelte.txt
+/svelte23.txt
+/rust.txt
+/rust23.txt
+/seph.txt
+/seph23.txt
+/automerge.txt
+/automerge23.txt
diff --git a/bench.mlb b/bench.mlb
index 82b749b..c82f437 100644
--- a/bench.mlb
+++ b/bench.mlb
@@ -1,5 +1,17 @@
 $(SML_LIB)/basis/basis.mlb
 
+ann
+  "allowVectorExps true"
+in
+  svelte.sml
+  rust.sml
+  seph.sml
+  automerge.sml
+end
+
 tiny_rope.sml
 rope.sml
+
+tiny_rope23.sml
+
 utils.sml
diff --git a/tiny_rope.sml b/tiny_rope.sml
index 64b08bd..dbac9b4 100644
--- a/tiny_rope.sml
+++ b/tiny_rope.sml
@@ -7,7 +7,7 @@ sig
   val insert: int * string * t -> t
   val append: string * t -> t
   val delete: int * int * t -> t
-  val toString: t -> string list
+  val toString: t -> string
   val foldFromIdxTerm: (char * 'a -> 'a) * ('a -> bool) * int * t * 'a -> 'a
   val foldFromIdx: (char * 'a -> 'a) * int * t * 'a -> 'a
 end
@@ -33,9 +33,15 @@ struct
     | N0 s => f (state, s)
     | _ => raise AuxConstructor
 
-  fun toStringFolder (acc, str) = str :: acc
-  fun toString rope =
-    foldr (toStringFolder, [], rope)
+  local
+    fun toListFolder (acc, str) = str :: acc
+    fun toList rope = foldr (toListFolder, [], rope)
+  in
+    fun toString rope =
+      let val lst = toList rope
+      in String.concat lst
+      end
+  end
 
   datatype balance = AddedNode | DeletedNode | NoAction
 
diff --git a/tiny_rope23.sml b/tiny_rope23.sml
index 2e5f455..c1d0e0d 100644
--- a/tiny_rope23.sml
+++ b/tiny_rope23.sml
@@ -30,6 +30,16 @@ struct
           foldr f state l
         end
 
+  local
+    fun toListFolder (str, lst) = str :: lst
+    fun toList rope =
+      foldr toListFolder [] rope
+  in
+    fun toString rope =
+      let val lst = toList rope
+      in String.concat lst
+      end
+  end
 
   (* Type used for balancing ropes, used only internally. *)
   datatype treeI =
@@ -133,7 +143,7 @@ struct
          * Ropes don't usually have N3 nodes so the way we accomodate this is:
          * If current index is less than left metadata, use same strategy as
          * recursing to the left as N2 nodes.
-         * Else if current index is less than middle metadata, 
+         * Else if current index is less than (left + middle) metadata, 
          * recurse to middle node while subtracting left metadata.
          * Else, recurse to right node while subtracting (left metadata +
          * middle metadata).
@@ -148,7 +158,7 @@ struct
              TI (l, lm) => TI (N3 (l, lm, m, mm, r, rm), lm + mm + rm)
            | OF (l1, lm1, l2, lm2) =>
                OF (N2 (l1, lm1, l2, lm2), lm1 + lm2, N2 (m, mm, r, rm), mm + rm))
-        else if curIdx < mm then
+        else if curIdx < (lm + mm) then
           (case ins (curIdx - lm, newStr, m) of
              TI (m, mm) => TI (N3 (l, lm, m, mm, r, rm), lm + mm + rm)
            | OF (m1, mm1, m2, mm2) =>
diff --git a/utils.sml b/utils.sml
index 670db21..639bc0b 100644
--- a/utils.sml
+++ b/utils.sml
@@ -19,20 +19,19 @@ fun runTxns arr =
   Vector.foldl
     (fn ((pos, delNum, insStr), rope) =>
        let
-         val rope = if delNum > 0 then Rope.delete (pos, delNum, rope) else rope
          val strSize = String.size insStr
          val rope =
-           if strSize > 0 then Rope.insert (pos, insStr, rope) else rope
+           if strSize > 0 then TinyRope23.insert (pos, insStr, rope) else rope
        in
          rope
-       end) Rope.empty arr
+       end) TinyRope23.empty arr
 
 fun runTxnsTime title arr =
   let val f = (fn () => runTxns arr)
   in timeFun title f
   end
 
-fun runToString rope = Rope.toString rope
+fun runToString rope = TinyRope23.toString rope
 
 fun runToStringTime title rope =
   let val f = (fn () => runToString rope)
@@ -74,9 +73,20 @@ fun writeFile filename acc =
     ()
   end
 
+fun write (fileName, rope) =
+  let
+    val str = TinyRope23.toString rope
+    val io = TextIO.openOut fileName
+    val _ = TextIO.output (io, str)
+    val _ = TextIO.closeOut io
+  in
+    ()
+  end
+
 fun main () =
   let
     (* Timing benchmarks. *)
+    val startTime = LargeInt.fromInt 0
     val _ = runTxns1000Times (999, svelte_arr, startTime)
     val _ = runTxns1000Times (999, rust_arr, startTime)
     val _ = runTxns1000Times (999, seph_arr, startTime)
@@ -84,16 +94,21 @@ fun main () =
 
     (* Tests that line metadata is correct; will fail if incorrect. *)
     val svelte = runTxns svelte_arr
-    val _ = Rope.verifyLines svelte
-
     val rust = runTxns rust_arr
-    val _ = Rope.verifyLines rust
-
     val seph = runTxns seph_arr
-    val _ = Rope.verifyLines seph
-
     val automerge = runTxns automerge_arr
-    val _ = Rope.verifyLines automerge
+
+    (*
+      val _ = Rope.verifyLines svelte
+      val _ = Rope.verifyLines rust
+      val _ = Rope.verifyLines seph
+      val _ = Rope.verifyLines automerge
+    *)
+
+    val _ = write ("svelte23.txt", svelte)
+    val _ = write ("rust23.txt", rust)
+    val _ = write ("seph23.txt", seph)
+    val _ = write ("automerge23.txt", automerge)
   in
     ()
   end