humza/sml-projects
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

when insert forces persistent-vector.sml to split, distribute half of nodes to left side and half of nodes to right side. (We avoid repeated tiny vectors this way, which reduces tree height and maintains balance.)

Browse Source
This commit is contained in:
Humza Shahid
2025-12-01 14:24:41 +00:00
parent 328a4e76f1
commit 6fba536f6f
1 changed files with 44 additions and 10 deletions
Download Patch File Download Diff File Expand all files Collapse all files

54
fcore/persistent-vector.sml
View File

@@ -363,7 +363,7 @@ struct
val rightSize = VectorSlice.full #[getMaxSize right]
val leftLen = SOME idx
val rightLen = SOME (idx - Vector.length nodes - 1)
val rightLen = SOME (Vector.length nodes - idx - 1)
val leftSizeSlice = VectorSlice.slice (sizes, 0, leftLen)
val rightSizeSlice = VectorSlice.slice (sizes, idx + 1, rightLen)
@@ -426,11 +426,28 @@ struct
if Vector.length sizes = maxSize then
(* have to split *)
let
val rightItems = #[{start = start, finish = finish}]
val rightSize = #[finish]
val right = LEAF (rightItems, rightSize)
val startLen = SOME halfSize
val midLen = SOME (Vector.length items - halfSize)
val leftSizes = VectorSlice.slice (sizes, 0, startLen)
val leftItems = VectorSlice.slice (items, 0, startLen)
val midSizes = VectorSlice.slice (sizes, halfSize, midLen)
val midItems = VectorSlice.slice (items, halfSize, midLen)
val rightSizes = VectorSlice.full #[finish]
val rightItems = VectorSlice.full #[{start = start, finish = finish}]
val rightItems = VectorSlice.concat [midItems, rightItems]
val leftItems = VectorSlice.vector leftItems
val rightSizes = VectorSlice.concat [midSizes, rightSizes]
val leftSizes = VectorSlice.vector leftSizes
val left = LEAF (leftItems, leftSizes)
val right = LEAF (rightItems, rightSizes)
in
INSERT_SPLIT (tree, right)
INSERT_SPLIT (left, right)
end
else
(* can just append *)
@@ -446,11 +463,28 @@ struct
if Vector.length sizes = maxSize then
(* have to split *)
let
val leftItems = #[{start = start, finish = finish}]
val leftSize = #[finish]
val left = LEAF (leftItems, leftSize)
val leftSizes = VectorSlice.full #[finish]
val leftItems = VectorSlice.full #[{start = start, finish = finish}]
val midLen = SOME halfSize
val rightLen = SOME (Vector.length items - halfSize)
val midSizes = VectorSlice.slice (sizes, 0, midLen)
val midItems = VectorSlice.slice (items, 0, midLen)
val rightSizes = VectorSlice.slice (sizes, halfSize, rightLen)
val rightItems = VectorSlice.slice (items, halfSize, rightLen)
val leftSizes = VectorSlice.concat [leftSizes, midSizes]
val rightSizes = VectorSlice.vector rightSizes
val leftItems = VectorSlice.concat [leftItems, midItems]
val rightItems = VectorSlice.vector rightItems
val left = LEAF (leftItems, leftSizes)
val right = LEAF (rightItems, rightSizes)
in
INSERT_SPLIT (left, tree)
INSERT_SPLIT (left, right)
end
else
(* just prepend *)
@@ -466,7 +500,7 @@ struct
let
val idx = BinSearch.equalOrMore (finish, sizes)
val leftLen = SOME idx
val rightLen = SOME (idx - Vector.length sizes)
val rightLen = SOME (Vector.length sizes - idx)
val leftSizes = VectorSlice.slice (sizes, 0, leftLen)
val rightSizes = VectorSlice.slice (sizes, idx, rightLen)