formatting for persistent-vector.sml (absolutely no changes other than formatting)

This commit is contained in:
2025-12-08 22:40:38 +00:00
parent 2ba18a38b0
commit d52c350a90

View File

@@ -104,10 +104,7 @@ struct
val prevFinish = Vector.sub (sizes, Vector.length sizes - 1)
val start = start - prevFinish
val finish = finish - prevFinish
val newNode = LEAF
( #[{start = start, finish = finish}]
, #[finish]
)
val newNode = LEAF (#[{start = start, finish = finish}], #[finish])
in
APPEND newNode
end
@@ -125,11 +122,8 @@ struct
case helpAppend (start, finish, tree) of
UPDATE t => t
| APPEND newNode =>
let
val maxSize = getFinishIdx tree
in
BRANCH
(#[tree, newNode], #[maxSize, finish])
let val maxSize = getFinishIdx tree
in BRANCH (#[tree, newNode], #[maxSize, finish])
end
fun getStart tree =
@@ -350,10 +344,8 @@ struct
case tree of
BRANCH (nodes, _) => getFirstItem (Vector.sub (nodes, 0))
| LEAF (items, _) =>
if Vector.length items = 0 then
{start = ~1, finish = ~1}
else
Vector.sub (items, 0)
if Vector.length items = 0 then {start = ~1, finish = ~1}
else Vector.sub (items, 0)
fun getMaxSize tree =
case tree of
@@ -366,15 +358,14 @@ struct
if offset <= Vector.sub (sizes, 0) then
splitLeft (offset, Vector.sub (nodes, 0))
else if offset >= Vector.sub (sizes, Vector.length sizes - 1) then
let
let
val prevSize =
if Vector.length sizes > 1 then
Vector.sub (sizes, Vector.length sizes - 1)
else
0
val result =
splitLeft
(offset - prevSize, Vector.sub (nodes, Vector.length nodes - 1))
val result = splitLeft (offset - prevSize, Vector.sub
(nodes, Vector.length nodes - 1))
in
if isEmpty result then
let
@@ -389,8 +380,10 @@ struct
else
let
val newChildSize = getMaxSize result + prevSize
val sizes = Vector.update (sizes, Vector.length sizes - 1, newChildSize)
val nodes = Vector.update (nodes, Vector.length nodes - 1, result)
val sizes = Vector.update
(sizes, Vector.length sizes - 1, newChildSize)
val nodes = Vector.update
(nodes, Vector.length nodes - 1, result)
in
BRANCH (nodes, sizes)
end
@@ -398,11 +391,7 @@ struct
else
let
val idx = BinSearch.equalOrMore (offset, sizes)
val prevSize =
if idx > 1 then
Vector.sub (sizes, idx - 1)
else
0
val prevSize = if idx > 1 then Vector.sub (sizes, idx - 1) else 0
val result = splitLeft (offset - prevSize, Vector.sub (nodes, idx))
in
if isEmpty result then
@@ -418,20 +407,11 @@ struct
else
let
val len = idx + 1
val sizes = Vector.tabulate (len,
fn i =>
if i = idx then
getMaxSize result + prevSize
else
Vector.sub (sizes, i)
)
val nodes = Vector.tabulate (len,
fn i =>
if i = idx then
result
else
Vector.sub (nodes, i)
)
val sizes = Vector.tabulate (len, fn i =>
if i = idx then getMaxSize result + prevSize
else Vector.sub (sizes, i))
val nodes = Vector.tabulate (len, fn i =>
if i = idx then result else Vector.sub (nodes, i))
in
BRANCH (nodes, sizes)
end
@@ -442,27 +422,27 @@ struct
tree
else if offset <= Vector.sub (sizes, 0) then
LEAF (#[], #[])
else
let
val len = BinSearch.equalOrMore (offset, sizes)
val sizes = VectorSlice.slice (sizes, 0, SOME len)
val sizes = VectorSlice.vector sizes
val items = VectorSlice.slice (items, 0, SOME len)
val items = VectorSlice.vector items
in
LEAF (items, sizes)
end
else
let
val len = BinSearch.equalOrMore (offset, sizes)
val sizes = VectorSlice.slice (sizes, 0, SOME len)
val sizes = VectorSlice.vector sizes
val items = VectorSlice.slice (items, 0, SOME len)
val items = VectorSlice.vector items
in
LEAF (items, sizes)
end
else
tree
(* Unlike 'splitLeft' which leaves the size metadata alone
* (except for splitting it),
* we want splitRight to decrement the size metadata
* by the largest entry in the size table that was split.
* This is so that we can maintain relative indexing metadata. *)
fun splitRight (offset, tree) =
case tree of
BRANCH (nodes, sizes) =>
(* Unlike 'splitLeft' which leaves the size metadata alone
* (except for splitting it),
* we want splitRight to decrement the size metadata
* by the largest entry in the size table that was split.
* This is so that we can maintain relative indexing metadata. *)
fun splitRight (offset, tree) =
case tree of
BRANCH (nodes, sizes) =>
if offset <= Vector.sub (sizes, 0) then
(* we want to split first node *)
let
@@ -474,7 +454,8 @@ struct
val len = Vector.length sizes - 1
val sizeSlice = VectorSlice.slice (sizes, 1, SOME len)
val sizes = VectorSlice.map (fn el => el - firstSizeBefore) sizeSlice
val sizes =
VectorSlice.map (fn el => el - firstSizeBefore) sizeSlice
val nodeSlice = VectorSlice.slice (nodes, 1, SOME len)
val nodes = VectorSlice.vector nodeSlice
@@ -486,12 +467,10 @@ struct
val firstSizeAfter = getMaxSize result
val sizeDiff = firstSizeBefore - firstSizeAfter
val sizes = Vector.mapi (fn (idx, el) =>
if idx = 0 then
firstSizeAfter
else
el - sizeDiff
) sizes
val sizes =
Vector.mapi
(fn (idx, el) =>
if idx = 0 then firstSizeAfter else el - sizeDiff) sizes
val nodes = Vector.update (nodes, 0, result)
in
@@ -536,351 +515,332 @@ struct
BRANCH (nodes, sizes)
end
end
| LEAF (items, sizes) =>
if offset > Vector.sub (sizes, Vector.length sizes - 1) then
LEAF (#[], #[])
else if offset <= Vector.sub (sizes, 0) then
tree
else
let
val idx = BinSearch.equalOrMore (offset, sizes)
val len = Vector.length sizes - idx
val len = SOME len
val prevSize =
if idx < 1 then
0
else
Vector.sub (sizes, idx - 1)
val sizes = VectorSlice.slice (sizes, idx, len)
val sizes = VectorSlice.map (fn i => i - prevSize) sizes
val items = VectorSlice.slice (items, idx, len)
val items =
VectorSlice.map
(fn {start, finish} =>
{start = start - prevSize, finish = finish - prevSize})
items
in
LEAF (items, sizes)
end
fun getDepth (tree, acc) =
case tree of
BRANCH (nodes, _) => getDepth (Vector.sub (nodes, 0), acc + 1)
| LEAF (_, _) => acc
fun getRootVecLength tree =
case tree of
BRANCH (_, sizes) => Vector.length sizes
| LEAF (_, sizes) => Vector.length sizes
fun joinSameDepth (left, right) =
case (left, right) of
(BRANCH (leftNodes, leftSizes), BRANCH (rightNodes, rightSizes)) =>
| LEAF (items, sizes) =>
if offset > Vector.sub (sizes, Vector.length sizes - 1) then
LEAF (#[], #[])
else if offset <= Vector.sub (sizes, 0) then
tree
else
let
val nodes = Vector.concat [leftNodes, rightNodes]
val maxLeftSize = Vector.sub (leftSizes, Vector.length leftSizes - 1)
val sizes = Vector.tabulate
(Vector.length leftSizes + Vector.length rightSizes,
fn i =>
if i < Vector.length leftSizes then
Vector.sub (leftSizes, i)
else
Vector.sub (rightSizes, i - Vector.length leftSizes)
+ maxLeftSize
)
in
BRANCH (nodes, sizes)
end
| (LEAF (leftItems, leftSizes), LEAF (rightItems, rightSizes)) =>
let
val maxLeftSize = Vector.sub (leftSizes, Vector.length leftSizes - 1)
val len = Vector.length leftItems + Vector.length rightItems
val idx = BinSearch.equalOrMore (offset, sizes)
val len = Vector.length sizes - idx
val len = SOME len
val prevSize = if idx < 1 then 0 else Vector.sub (sizes, idx - 1)
val sizes = VectorSlice.slice (sizes, idx, len)
val sizes = VectorSlice.map (fn i => i - prevSize) sizes
val items = VectorSlice.slice (items, idx, len)
val items =
Vector.tabulate (len,
fn i =>
if i < Vector.length leftItems then
Vector.sub (leftItems, i)
else
let
val {start, finish} = Vector.sub (rightItems, i - Vector.length leftItems)
in
{start = start + maxLeftSize, finish = finish + maxLeftSize}
end
)
val sizes =
Vector.tabulate (len,
fn i =>
if i < Vector.length leftSizes then
Vector.sub (leftSizes, i)
else
Vector.sub (rightSizes, i - Vector.length leftSizes)
+ maxLeftSize
)
VectorSlice.map
(fn {start, finish} =>
{start = start - prevSize, finish = finish - prevSize}) items
in
LEAF (items, sizes)
end
| _ => raise Fail "PersistentVector.joinSameDepth: one is BRANCH and other is LEAF"
datatype append_join_result =
APPEND_JOIN_APPEND of t
| APPEND_JOIN_UPDATE of t
fun getDepth (tree, acc) =
case tree of
BRANCH (nodes, _) => getDepth (Vector.sub (nodes, 0), acc + 1)
| LEAF (_, _) => acc
fun appendJoin (left, right, joinDepth, rightLength) =
case left of
BRANCH (nodes, sizes) =>
if joinDepth = 0 then
(* base case: should join at this depth *)
if Vector.length nodes + rightLength > maxSize then
APPEND_JOIN_APPEND right
else
(case right of
BRANCH (rightNodes, rightSizes) =>
let
val nodes = Vector.concat [nodes, rightNodes]
fun getRootVecLength tree =
case tree of
BRANCH (_, sizes) => Vector.length sizes
| LEAF (_, sizes) => Vector.length sizes
val lastLeftSize = Vector.sub (sizes, Vector.length sizes - 1)
val sizes = Vector.tabulate (Vector.length nodes,
fn i =>
if i < Vector.length sizes then
Vector.sub (sizes, i)
else
Vector.sub (rightSizes, i - Vector.length sizes)
+ lastLeftSize
)
in
APPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
| LEAF _ =>
raise Fail
"persistent-vector.sml appendJoin: \
\expected to join when left and right are both BRANCH \
\but left is BRANCH and right is LEAF"
)
else
(* recursion case: join below *)
let
val lastIdx = Vector.length nodes - 1
val lastNode = Vector.sub (nodes, lastIdx)
in
case appendJoin (lastNode, right, joinDepth - 1, rightLength) of
APPEND_JOIN_UPDATE newLast =>
let
val prevSize =
if lastIdx > 0 then Vector.sub (sizes, lastIdx - 1)
else 0
val newLastSize = getMaxSize newLast + prevSize
val sizes = Vector.update (sizes, lastIdx, newLastSize)
val nodes = Vector.update (nodes, lastIdx, newLast)
in
APPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
| APPEND_JOIN_APPEND newNode =>
if Vector.length nodes = maxSize then
(* parent has to append insead as this node
* would exceed capacity if appended here *)
APPEND_JOIN_APPEND (BRANCH (#[newNode], #[getMaxSize newNode]))
fun joinSameDepth (left, right) =
case (left, right) of
(BRANCH (leftNodes, leftSizes), BRANCH (rightNodes, rightSizes)) =>
let
val nodes = Vector.concat [leftNodes, rightNodes]
val maxLeftSize = Vector.sub (leftSizes, Vector.length leftSizes - 1)
val sizes =
Vector.tabulate
( Vector.length leftSizes + Vector.length rightSizes
, fn i =>
if i < Vector.length leftSizes then
Vector.sub (leftSizes, i)
else
let
val prevSize =
Vector.sub (sizes, Vector.length sizes - 1)
val newNodeSize = #[getMaxSize newNode + prevSize]
val sizes = Vector.concat [sizes, newNodeSize]
Vector.sub (rightSizes, i - Vector.length leftSizes)
+ maxLeftSize
)
in
BRANCH (nodes, sizes)
end
| (LEAF (leftItems, leftSizes), LEAF (rightItems, rightSizes)) =>
let
val maxLeftSize = Vector.sub (leftSizes, Vector.length leftSizes - 1)
val len = Vector.length leftItems + Vector.length rightItems
val items = Vector.tabulate (len, fn i =>
if i < Vector.length leftItems then
Vector.sub (leftItems, i)
else
let
val {start, finish} = Vector.sub
(rightItems, i - Vector.length leftItems)
in
{start = start + maxLeftSize, finish = finish + maxLeftSize}
end)
val sizes = Vector.tabulate (len, fn i =>
if i < Vector.length leftSizes then
Vector.sub (leftSizes, i)
else
Vector.sub (rightSizes, i - Vector.length leftSizes) + maxLeftSize)
in
LEAF (items, sizes)
end
| _ =>
raise Fail
"PersistentVector.joinSameDepth: one is BRANCH and other is LEAF"
val newNode = #[newNode]
val nodes = Vector.concat [nodes, newNode]
in
APPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
end
| LEAF (items, sizes) =>
(* joinDepth should = 0, and we assume it is *)
if Vector.length items + rightLength > maxSize then
datatype append_join_result =
APPEND_JOIN_APPEND of t
| APPEND_JOIN_UPDATE of t
fun appendJoin (left, right, joinDepth, rightLength) =
case left of
BRANCH (nodes, sizes) =>
if joinDepth = 0 then
(* base case: should join at this depth *)
if Vector.length nodes + rightLength > maxSize then
APPEND_JOIN_APPEND right
else
(case right of
LEAF (rightItems, rightSizes) =>
BRANCH (rightNodes, rightSizes) =>
let
val nodes = Vector.concat [nodes, rightNodes]
val lastLeftSize = Vector.sub
(sizes, Vector.length sizes - 1)
val sizes = Vector.tabulate (Vector.length nodes, fn i =>
if i < Vector.length sizes then
Vector.sub (sizes, i)
else
Vector.sub (rightSizes, i - Vector.length sizes)
+ lastLeftSize)
in
APPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
| LEAF _ =>
raise Fail
"persistent-vector.sml appendJoin: \
\expected to join when left and right are both BRANCH \
\but left is BRANCH and right is LEAF")
else
(* recursion case: join below *)
let
val lastIdx = Vector.length nodes - 1
val lastNode = Vector.sub (nodes, lastIdx)
in
case appendJoin (lastNode, right, joinDepth - 1, rightLength) of
APPEND_JOIN_UPDATE newLast =>
let
val leftMaxSize = Vector.sub (sizes, Vector.length sizes - 1)
val newLen = Vector.length items + Vector.length rightItems
val items = Vector.tabulate (newLen,
fn i =>
if i < Vector.length items then
Vector.sub (items, i)
else
let
val {start, finish} = Vector.sub (rightItems, i - Vector.length items)
in
{start = start + leftMaxSize, finish = finish + leftMaxSize}
end
)
val sizes = Vector.tabulate (newLen,
fn i =>
if i < Vector.length sizes then
Vector.sub (sizes, i)
else
Vector.sub (rightSizes, i - Vector.length sizes)
+ leftMaxSize
)
val prevSize =
if lastIdx > 0 then Vector.sub (sizes, lastIdx - 1) else 0
val newLastSize = getMaxSize newLast + prevSize
val sizes = Vector.update (sizes, lastIdx, newLastSize)
val nodes = Vector.update (nodes, lastIdx, newLast)
in
APPEND_JOIN_UPDATE (LEAF (items, sizes))
APPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
| BRANCH _ =>
raise Fail
"persistent-vector.sml appendJoin: \
\left is LEAF and expected right to also be LEAF \
\but right is BRANCH"
)
datatype prepend_join_result =
PREPEND_JOIN_PREPEND of t
| PREPEND_JOIN_UPDATE of t
fun prependJoin (left, right, joinDepth, leftLength) =
case right of
BRANCH (rightNodes, rightSizes) =>
if joinDepth = 0 then
(* base case: join *)
if Vector.length rightNodes + leftLength > maxSize then
PREPEND_JOIN_PREPEND left
else
(case left of
BRANCH (leftNodes, leftSizes) =>
| APPEND_JOIN_APPEND newNode =>
if Vector.length nodes = maxSize then
(* parent has to append insead as this node
* would exceed capacity if appended here *)
APPEND_JOIN_APPEND (BRANCH
(#[newNode], #[getMaxSize newNode]))
else
let
val nodes = Vector.concat [leftNodes, rightNodes]
val maxLeftSize =
Vector.sub (leftSizes, Vector.length leftSizes - 1)
val sizes = Vector.tabulate (Vector.length nodes,
fn i =>
if i < Vector.length leftSizes then
Vector.sub (leftSizes, i)
else
Vector.sub (rightSizes, i - Vector.length leftSizes)
+ maxLeftSize
)
in
PREPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
| LEAF _ =>
raise Fail
"persistent-vector.sml prependJoin: \
\expected left and right to be BRANCH \
\but right is BRANCH while left is LEAF"
)
else
(* recursive case *)
let
val firstRightNode = Vector.sub (rightNodes, 0)
val firstRightSize = getMaxSize firstRightNode
in
(case prependJoin (left, firstRightNode, joinDepth - 1, leftLength) of
PREPEND_JOIN_UPDATE newFirst =>
let
val newFirstSize = getMaxSize newFirst
val sizeDiff = newFirstSize - firstRightSize
val sizes = Vector.map (fn el => el + sizeDiff) rightSizes
val nodes = Vector.update (rightNodes, 0, newFirst)
in
PREPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
| PREPEND_JOIN_PREPEND newFirst =>
if Vector.length rightSizes = maxSize then
PREPEND_JOIN_PREPEND (BRANCH (#[newFirst], #[getMaxSize newFirst]))
else
let
val nodes = Vector.concat [#[newFirst], rightNodes]
val newFirstSize = getMaxSize newFirst
val prevSize = Vector.sub (sizes, Vector.length sizes - 1)
val newNodeSize = #[getMaxSize newNode + prevSize]
val sizes = Vector.concat [sizes, newNodeSize]
val sizes = Vector.tabulate (Vector.length nodes,
fn i =>
if i = 0 then
newFirstSize
else
Vector.sub (rightSizes, i - 1) + newFirstSize
)
in
PREPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end)
end
| LEAF (rightItems, rightSizes) =>
(* joinDepth should = 0, and we assume it is *)
if Vector.length rightItems + leftLength > maxSize then
val newNode = #[newNode]
val nodes = Vector.concat [nodes, newNode]
in
APPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
end
| LEAF (items, sizes) =>
(* joinDepth should = 0, and we assume it is *)
if Vector.length items + rightLength > maxSize then
APPEND_JOIN_APPEND right
else
(case right of
LEAF (rightItems, rightSizes) =>
let
val leftMaxSize = Vector.sub (sizes, Vector.length sizes - 1)
val newLen = Vector.length items + Vector.length rightItems
val items = Vector.tabulate (newLen, fn i =>
if i < Vector.length items then
Vector.sub (items, i)
else
let
val {start, finish} = Vector.sub
(rightItems, i - Vector.length items)
in
{ start = start + leftMaxSize
, finish = finish + leftMaxSize
}
end)
val sizes = Vector.tabulate (newLen, fn i =>
if i < Vector.length sizes then
Vector.sub (sizes, i)
else
Vector.sub (rightSizes, i - Vector.length sizes)
+ leftMaxSize)
in
APPEND_JOIN_UPDATE (LEAF (items, sizes))
end
| BRANCH _ =>
raise Fail
"persistent-vector.sml appendJoin: \
\left is LEAF and expected right to also be LEAF \
\but right is BRANCH")
datatype prepend_join_result =
PREPEND_JOIN_PREPEND of t
| PREPEND_JOIN_UPDATE of t
fun prependJoin (left, right, joinDepth, leftLength) =
case right of
BRANCH (rightNodes, rightSizes) =>
if joinDepth = 0 then
(* base case: join *)
if Vector.length rightNodes + leftLength > maxSize then
PREPEND_JOIN_PREPEND left
else
(case left of
LEAF (leftItems, leftSizes) =>
let
val maxLeftSize = Vector.sub (leftSizes, Vector.length leftSizes - 1)
val len = Vector.length leftSizes + Vector.length rightItems
val sizes = Vector.tabulate (len,
fn i =>
if i < Vector.length leftSizes then
Vector.sub (leftSizes, i)
else
Vector.sub (rightSizes, i - Vector.length leftSizes)
+ maxLeftSize)
val items = Vector.tabulate (len,
fn i =>
if i < Vector.length leftItems then
Vector.sub (leftItems, i)
else
let
val {start, finish} =
Vector.sub (rightItems, i - Vector.length leftItems)
in
{start = start + maxLeftSize, finish = finish + maxLeftSize}
end
)
in
PREPEND_JOIN_UPDATE (LEAF (items, sizes))
end
| BRANCH _ =>
raise Fail
"persistent-vector.sml prependJoin: \
\expected left and right to be LEAF \
\but right is LEAF while left is BRANCH")
BRANCH (leftNodes, leftSizes) =>
let
val nodes = Vector.concat [leftNodes, rightNodes]
val maxLeftSize = Vector.sub
(leftSizes, Vector.length leftSizes - 1)
val sizes = Vector.tabulate (Vector.length nodes, fn i =>
if i < Vector.length leftSizes then
Vector.sub (leftSizes, i)
else
Vector.sub (rightSizes, i - Vector.length leftSizes)
+ maxLeftSize)
in
PREPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
| LEAF _ =>
raise Fail
"persistent-vector.sml prependJoin: \
\expected left and right to be BRANCH \
\but right is BRANCH while left is LEAF")
else
(* recursive case *)
let
val firstRightNode = Vector.sub (rightNodes, 0)
val firstRightSize = getMaxSize firstRightNode
in
(case prependJoin (left, firstRightNode, joinDepth - 1, leftLength) of
PREPEND_JOIN_UPDATE newFirst =>
let
val newFirstSize = getMaxSize newFirst
val sizeDiff = newFirstSize - firstRightSize
val sizes = Vector.map (fn el => el + sizeDiff) rightSizes
val nodes = Vector.update (rightNodes, 0, newFirst)
in
PREPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end
| PREPEND_JOIN_PREPEND newFirst =>
if Vector.length rightSizes = maxSize then
PREPEND_JOIN_PREPEND (BRANCH
(#[newFirst], #[getMaxSize newFirst]))
else
let
val nodes = Vector.concat [#[newFirst], rightNodes]
val newFirstSize = getMaxSize newFirst
fun join (left, right) =
if isEmpty left then
right
else if isEmpty right then
left
else
let
val leftDepth = getDepth (left, 0)
val rightDepth = getDepth (right, 0)
in
if leftDepth = rightDepth then
if getRootVecLength left + getRootVecLength right <= maxSize then
joinSameDepth (left, right)
else
let
val ls = getMaxSize left
val rs = getMaxSize right + ls
val sizes = #[ls, rs]
val nodes = #[left, right]
in
BRANCH (nodes, sizes)
end
else if leftDepth > rightDepth then
val sizes = Vector.tabulate (Vector.length nodes, fn i =>
if i = 0 then newFirstSize
else Vector.sub (rightSizes, i - 1) + newFirstSize)
in
PREPEND_JOIN_UPDATE (BRANCH (nodes, sizes))
end)
end
| LEAF (rightItems, rightSizes) =>
(* joinDepth should = 0, and we assume it is *)
if Vector.length rightItems + leftLength > maxSize then
PREPEND_JOIN_PREPEND left
else
(case left of
LEAF (leftItems, leftSizes) =>
let
val maxLeftSize = Vector.sub
(leftSizes, Vector.length leftSizes - 1)
val len = Vector.length leftSizes + Vector.length rightItems
val sizes = Vector.tabulate (len, fn i =>
if i < Vector.length leftSizes then
Vector.sub (leftSizes, i)
else
Vector.sub (rightSizes, i - Vector.length leftSizes)
+ maxLeftSize)
val items = Vector.tabulate (len, fn i =>
if i < Vector.length leftItems then
Vector.sub (leftItems, i)
else
let
val {start, finish} = Vector.sub
(rightItems, i - Vector.length leftItems)
in
{ start = start + maxLeftSize
, finish = finish + maxLeftSize
}
end)
in
PREPEND_JOIN_UPDATE (LEAF (items, sizes))
end
| BRANCH _ =>
raise Fail
"persistent-vector.sml prependJoin: \
\expected left and right to be LEAF \
\but right is LEAF while left is BRANCH")
fun join (left, right) =
if isEmpty left then
right
else if isEmpty right then
left
else
let
val leftDepth = getDepth (left, 0)
val rightDepth = getDepth (right, 0)
in
if leftDepth = rightDepth then
if getRootVecLength left + getRootVecLength right <= maxSize then
joinSameDepth (left, right)
else
let
val joinDepth = leftDepth - rightDepth
val rightLength = getRootVecLength right
val ls = getMaxSize left
val rs = getMaxSize right + ls
val sizes = #[ls, rs]
val nodes = #[left, right]
in
case appendJoin (left, right, joinDepth, rightLength) of
APPEND_JOIN_UPDATE t => t
| APPEND_JOIN_APPEND newRight =>
let
val ls = getMaxSize left
val rs = getMaxSize right + ls
val sizes = #[ls, rs]
val nodes = #[left, newRight]
in
BRANCH (nodes, sizes)
end
BRANCH (nodes, sizes)
end
else if leftDepth > rightDepth then
let
val joinDepth = leftDepth - rightDepth
val rightLength = getRootVecLength right
in
case appendJoin (left, right, joinDepth, rightLength) of
APPEND_JOIN_UPDATE t => t
| APPEND_JOIN_APPEND newRight =>
let
val ls = getMaxSize left
val rs = getMaxSize right + ls
val sizes = #[ls, rs]
val nodes = #[left, newRight]
in
BRANCH (nodes, sizes)
end
end
else
let
val joinDepth = rightDepth - leftDepth