From e619fd1c05ed15203b23a69309d4c94ff83abf46 Mon Sep 17 00:00:00 2001
From: Humza Shahid <humzasaur@gmail.com>
Date: Sun, 19 Jan 2025 13:03:16 +0000
Subject: [PATCH] change API of BinVec

---
 fcore/bin-vec.sml | 114 +++++++++++++++++++++++++---------------------
 1 file changed, 61 insertions(+), 53 deletions(-)

diff --git a/fcore/bin-vec.sml b/fcore/bin-vec.sml
index ec0f2bd..d6be46b 100644
--- a/fcore/bin-vec.sml
+++ b/fcore/bin-vec.sml
@@ -1,37 +1,32 @@
-signature BIN_VEC =
+signature MAKE_BIN_VEC =
 sig
-  (* char is just 8 bits, which is smaller than int's 32 bits 
-   * and smaller = faster here*)
-  type elem = char
-  type t = char vector
+  type elem
 
-  val singleton: elem -> t
-  val getIndex: t * elem -> int
-  val insert: t * elem -> t
+  val l: elem * elem -> bool
+  val eq: elem * elem -> bool
+  val g: elem * elem -> bool
 end
 
-structure BinVec: BIN_VEC =
+signature BIN_VEC =
+sig
+  type elem
+
+  val empty: elem vector
+
+  val sub: elem vector * int -> elem
+
+  val findInsPos: elem * elem vector -> int
+  val insert: elem vector * elem * int -> elem vector
+  val delete: elem vector * elem -> elem vector
+end
+
+functor MakeBinVec(Fn: MAKE_BIN_VEC): BIN_VEC =
 struct
-  type elem = char
-  type t = char vector
+  type elem = Fn.elem
 
-  fun singleton x = Vector.fromList [x]
+  val empty = Vector.fromList []
 
-  fun helpFind (findNum, vec, low, high) =
-    if high >= low then
-      let
-        val mid = low + ((high - low) div 2)
-        val curNum = Vector.sub (vec, mid)
-      in
-        if curNum = findNum then mid
-        else if curNum < findNum then helpFind (findNum, vec, mid + 1, high)
-        else helpFind (findNum, vec, low, mid - 1)
-      end
-    else
-      ~1
-
-  fun getIndex (vec: t, findNum: elem) =
-    helpFind (findNum, vec, 0, Vector.length vec - 1)
+  val sub = Vector.sub
 
   fun reverseLinearSearch (pos, findNum, vec) =
     if pos < 0 then
@@ -40,7 +35,7 @@ struct
       let
         val curNum = Vector.sub (vec, pos)
       in
-        if findNum > curNum then pos + 1
+        if Fn.g (findNum, curNum) then pos + 1
         else reverseLinearSearch (pos - 1, findNum, vec)
       end
 
@@ -51,7 +46,7 @@ struct
       let
         val curNum = Vector.sub (vec, pos)
       in
-        if findNum > curNum then pos
+        if Fn.g (findNum, curNum) then pos
         else forwardLinearSearch (pos + 1, findNum, vec)
       end
 
@@ -61,9 +56,9 @@ struct
         val mid = low + ((high - low) div 2)
         val curNum = Vector.sub (vec, mid)
       in
-        if curNum = findNum then
+        if Fn.eq (curNum, findNum) then
           mid
-        else if curNum < findNum then
+        else if Fn.l (curNum, findNum) then
           helpFindInsPos (findNum, vec, mid + 1, high, mid)
         else
           helpFindInsPos (findNum, vec, low, mid - 1, mid)
@@ -72,36 +67,39 @@ struct
       let
         val curNum = Vector.sub (vec, prevMid)
       in
-        if findNum < curNum then forwardLinearSearch (prevMid, findNum, vec)
-        else reverseLinearSearch (prevMid, findNum, vec)
+        if Fn.l (findNum, curNum) then
+          forwardLinearSearch (prevMid, findNum, vec)
+        else
+          reverseLinearSearch (prevMid, findNum, vec)
       end
 
   fun findInsPos (findNum, vec) =
     if Vector.length vec = 0 then ~1
     else helpFindInsPos (findNum, vec, 0, Vector.length vec - 1, 0)
 
-  fun insert (vec: t, elem: elem) =
-    let
-      val insPos = findInsPos (elem, vec)
-    in
-      if insPos < 0 then
-        Vector.concat [Vector.fromList [elem], vec]
-      else if insPos = Vector.length vec then
-        Vector.concat [vec, Vector.fromList [elem]]
-      else
-        let
-          val elem = Vector.fromList [elem]
-          val elem = VectorSlice.full elem
+  (* insPos parameter should be the unmodified result of calling findInsPos.
+   * The reason the insert function does not call findInsPos directly is so,
+   * if two BinVecs are used (one for keys and another for values like a map) 
+   * then the insert function can be used for both the key vector and value
+   * vector *)
+  fun insert (vec, elem, insPos) =
+    if insPos < 0 then
+      Vector.concat [Vector.fromList [elem], vec]
+    else if insPos = Vector.length vec then
+      Vector.concat [vec, Vector.fromList [elem]]
+    else
+      let
+        val elem = Vector.fromList [elem]
+        val elem = VectorSlice.full elem
 
-          val s2len = Vector.length vec - insPos
-          val slice1 = VectorSlice.slice (vec, 0, SOME insPos)
-          val slice2 = VectorSlice.slice (vec, insPos, SOME s2len)
-        in
-          VectorSlice.concat [slice1, elem, slice2]
-        end
-    end
+        val s2len = Vector.length vec - insPos
+        val slice1 = VectorSlice.slice (vec, 0, SOME insPos)
+        val slice2 = VectorSlice.slice (vec, insPos, SOME s2len)
+      in
+        VectorSlice.concat [slice1, elem, slice2]
+      end
 
-  fun delete (vec, elem) =
+  fun delete (vec, elem: elem) =
     let
       val insPos = findInsPos (elem, vec)
     in
@@ -118,3 +116,13 @@ struct
         end
     end
 end
+
+structure IntBinVec =
+  MakeBinVec
+    (struct
+       type elem = int
+
+       val l = Int.<
+       fun eq (a, b) = a = b
+       val g = Int.>
+     end)