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finish initial implementation for 'PersistentVector.splitRight'

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This commit is contained in:
Humza Shahid
2026-01-16 22:16:44 +00:00
parent eb316d7be2
commit ddcb0ea56d
1 changed files with 74 additions and 37 deletions
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111
fcore/persistent-vector.sml
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@@ -364,46 +364,49 @@ struct
end
end
| BRANCH (nodes, sizes) =>
if splitIdx < Vector.sub (sizes, 0) then
(* we want to split first node from rest *)
splitLeft (splitIdx, Vector.sub (nodes, 0))
else if splitIdx > Vector.sub (sizes, Vector.length sizes - 1) then
(* split point is after this subtree,
* so return this subtree unchanged *)
if Vector.length nodes = 0 then
tree
else
(* we want to split from somewhere in middle *)
let
val idx = BinSearch.equalOrMore (splitIdx, sizes)
val prevSize =
if idx = 0 then
0
else
if splitIdx < Vector.sub (sizes, 0) then
(* we want to split first node from rest *)
splitLeft (splitIdx, Vector.sub (nodes, 0))
else if splitIdx > Vector.sub (sizes, Vector.length sizes - 1) then
(* split point is after this subtree,
* so return this subtree unchanged *)
tree
else
(* we want to split from somewhere in middle *)
let
val idx = BinSearch.equalOrMore (splitIdx, sizes)
val prevSize =
if idx = 0 then
0
else
Vector.sub (sizes, idx - 1)
val child =
splitLeft (splitIdx - prevSize, Vector.sub (nodes, idx))
val sizes = VectorSlice.slice (sizes, 0, SOME idx)
val nodes = VectorSlice.slice (nodes, 0, SOME idx)
in
if isEmpty child then
let
val sizes = VectorSlice.vector sizes
val nodes = VectorSlice.vector nodes
in
BRANCH (nodes, sizes)
end
else
Vector.sub (sizes, idx - 1)
val child =
splitLeft (splitIdx - prevSize, Vector.sub (nodes, idx))
let
val childSize = VectorSlice.full #[getFinishIdx child + prevSize]
val sizes =VectorSlice.concat [sizes, childSize]
val sizes = VectorSlice.slice (sizes, 0, SOME idx)
val nodes = VectorSlice.slice (nodes, 0, SOME idx)
in
if isEmpty child then
let
val sizes = VectorSlice.vector sizes
val nodes = VectorSlice.vector nodes
in
BRANCH (nodes, sizes)
end
else
let
val childSize = VectorSlice.full #[getFinishIdx child + prevSize]
val sizes =VectorSlice.concat [sizes, childSize]
val childNode = VectorSlice.full #[child]
val nodes = VectorSlice.concat [nodes, childNode]
in
BRANCH (nodes, sizes)
end
end
val childNode = VectorSlice.full #[child]
val nodes = VectorSlice.concat [nodes, childNode]
in
BRANCH (nodes, sizes)
end
end
(* When we split in this function,
* we always want to update the sizes vector
@@ -462,6 +465,40 @@ struct
BRANCH (nodes, sizes)
end
end
| LEAF (items, sizes) =>
if Vector.length items = 0 then
tree
else
if splitIdx > Vector.sub (sizes, Vector.length sizes - 1) then
empty
else if splitIdx < Vector.sub (sizes, 0) then
tree
else
let
val idx = BinSearch.equalOrMore (splitIdx, sizes)
val {start, finish} = Vector.sub (items, idx)
val idx =
if splitIdx >= start then
idx + 1
else
idx
in
if idx >= Vector.length items then
empty
else
let
val len = Vector.length items - idx
val itemsSlice = VectorSlice.slice (items, idx, SOME len)
val items = VectorSlice.map
(fn {start, finish} =>
{start = start - splitIdx, finish = finish - splitIdx}
)
itemsSlice
val sizes = Vector.map #finish items
in
LEAF (items, sizes)
end
end
(* functions only for testing *)
fun fromListLoop (lst, acc) =