545 lines
18 KiB
Standard ML
545 lines
18 KiB
Standard ML
structure PersistentVector =
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struct
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(* Clojure-style persistent vector, for building search list.
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* There is an "int table" too, which stores the last index
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* at the node with the same index.
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* We can use the size table for binary search.
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* *)
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datatype t =
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BRANCH of t vector * int vector
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| LEAF of {start: int, finish: int} vector * int vector
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val maxSize = 32
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val halfSize = 16
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fun isEmpty t =
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case t of
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LEAF (_, sizes) => Vector.length sizes = 0
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| _ => false
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val empty = LEAF (#[], #[])
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datatype append_result = APPEND of t | UPDATE of t
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fun isInRange (checkIdx, t) =
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case t of
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BRANCH (nodes, sizes) =>
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let
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val searchIdx = BinSearch.equalOrMore (checkIdx, sizes)
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in
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if searchIdx = ~1 then
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false
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else if searchIdx = 0 then
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isInRange (checkIdx, Vector.sub (nodes, searchIdx))
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else
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let val nextCheckIdx = checkIdx - Vector.sub (sizes, searchIdx - 1)
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in isInRange (nextCheckIdx, Vector.sub (nodes, searchIdx))
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end
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end
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| LEAF (values, sizes) =>
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let
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val searchIdx = BinSearch.equalOrMore (checkIdx, sizes)
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in
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if searchIdx = ~1 then
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false
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else
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let val {start, finish} = Vector.sub (values, searchIdx)
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in checkIdx >= start andalso checkIdx <= finish
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end
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end
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fun getFinishIdx t =
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case t of
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BRANCH (_, sizes) => Vector.sub (sizes, Vector.length sizes - 1)
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| LEAF (_, sizes) => Vector.sub (sizes, Vector.length sizes - 1)
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fun helpAppend (start, finish, tree) =
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case tree of
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BRANCH (nodes, sizes) =>
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let
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val lastNode = Vector.sub (nodes, Vector.length nodes - 1)
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val prevSize =
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if Vector.length sizes > 1 then
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Vector.sub (sizes, Vector.length sizes - 2)
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else
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0
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in
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case helpAppend (start - prevSize, finish - prevSize, lastNode) of
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UPDATE newLast =>
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let
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val lastPos = Vector.length nodes - 1
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val newNode = Vector.update (nodes, lastPos, newLast)
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val newSizes = Vector.update (sizes, lastPos, finish)
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val newNode = BRANCH (newNode, newSizes)
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in
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UPDATE newNode
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end
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| APPEND newVec =>
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if Vector.length nodes = maxSize then
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let
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(* adjust "finish" so that it does not consider
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* offset for "lower" vector *)
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val finish =
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finish - Vector.sub (sizes, Vector.length sizes - 1)
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val newNode = BRANCH
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(#[newVec], #[finish])
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in
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APPEND newNode
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end
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else
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let
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val newNodes = Vector.concat [nodes, #[newVec]]
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val newSizes = Vector.concat [sizes, #[finish]]
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val newNodes = BRANCH (newNodes, newSizes)
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in
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UPDATE newNodes
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end
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end
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| LEAF (values, sizes) =>
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if Vector.length values + 1 > maxSize then
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(* when we split a leaf into two vectors,
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* we want to adjust the start and finish parameters
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* so that they don't contain the offset relevant to the
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* "lower" vector, which was split from *)
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let
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val prevFinish = Vector.sub (sizes, Vector.length sizes - 1)
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val start = start - prevFinish
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val finish = finish - prevFinish
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val newNode = LEAF
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( #[{start = start, finish = finish}]
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, #[finish]
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)
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in
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APPEND newNode
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end
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else
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let
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val newNode = Vector.concat
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[values, #[{start = start, finish = finish}]]
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val newSizes = Vector.concat [sizes, #[finish]]
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val newNode = LEAF (newNode, newSizes)
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in
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UPDATE newNode
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end
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fun append (start, finish, tree) =
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case helpAppend (start, finish, tree) of
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UPDATE t => t
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| APPEND newNode =>
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let
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val maxSize = getFinishIdx tree
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in
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BRANCH
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(#[tree, newNode], #[maxSize, finish])
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end
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fun getStart tree =
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case tree of
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LEAF (values, _) => Vector.sub (values, 0)
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| BRANCH (nodes, _) => getStart (Vector.sub (nodes, 0))
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fun helpNextMatch (cursorIdx, tree, acc) =
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case tree of
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LEAF (values, sizes) =>
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let
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val idx = BinSearch.equalOrMore (cursorIdx, sizes)
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in
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if idx = ~1 then
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{start = ~1, finish = ~1}
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else
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let val {start, finish} = Vector.sub (values, idx)
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in {start = start + acc, finish = finish + acc}
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end
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end
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| BRANCH (nodes, sizes) =>
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let
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val idx = BinSearch.equalOrMore (cursorIdx, sizes)
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in
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if idx = ~1 then
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{start = ~1, finish = ~1}
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else
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let
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val prevSize = if idx = 0 then 0 else Vector.sub (sizes, idx - 1)
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val acc = acc + prevSize
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val cursorIdx = cursorIdx - prevSize
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in
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helpNextMatch (cursorIdx, Vector.sub (nodes, idx), acc)
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end
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end
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fun startNextMatch (cursorIdx, tree) =
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case tree of
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LEAF (values, sizes) =>
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if Vector.length sizes = 0 then
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{start = ~1, finish = ~1}
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else
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let
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val idx = BinSearch.equalOrMore (cursorIdx, sizes)
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val idx = if idx = ~1 then 0 else idx
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in
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Vector.sub (values, idx)
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end
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| BRANCH (nodes, sizes) =>
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let
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val idx = BinSearch.equalOrMore (cursorIdx, sizes)
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in
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if idx = ~1 then
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{start = ~1, finish = ~1}
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else
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let
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val prevSize = if idx = 0 then 0 else Vector.sub (sizes, idx - 1)
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val cursorIdx = cursorIdx - prevSize
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in
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helpNextMatch (cursorIdx, Vector.sub (nodes, idx), prevSize)
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end
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end
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fun loopNextMatch (prevStart, prevFinish, tree, count) =
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if count = 0 then
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prevStart
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else
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let
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val {start, finish} = startNextMatch (prevFinish + 1, tree)
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in
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if start = ~1 then
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let val {start, finish} = getStart tree
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in loopNextMatch (start, finish, tree, count - 1)
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end
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else
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loopNextMatch (start, finish, tree, count - 1)
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end
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fun nextMatch (cursorIdx, tree, count) =
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if isEmpty tree then
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~1
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else
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let
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val {start, finish} = startNextMatch (cursorIdx, tree)
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in
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if start = ~1 then
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let val {start, finish} = getStart tree
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in loopNextMatch (start, finish, tree, count - 1)
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end
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else
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let in
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if cursorIdx >= start andalso cursorIdx <= finish then
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loopNextMatch (start, finish, tree, count)
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else
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loopNextMatch (start, finish, tree, count - 1)
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end
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end
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fun getLast (tree, acc) =
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case tree of
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LEAF (values, _) =>
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let val {start, finish} = Vector.sub (values, Vector.length values - 1)
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in {start = start + acc, finish = finish + acc}
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end
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| BRANCH (nodes, sizes) =>
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let
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val acc =
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if Vector.length sizes > 1 then
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acc + Vector.sub (sizes, Vector.length sizes - 1)
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else
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acc
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in
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getLast (Vector.sub (nodes, Vector.length nodes - 1), acc)
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end
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(* slightly tricky.
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* The `sizes` vector contains the last/finish position of the item
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* at the corresponding index in the `nodes` or `values` vector
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* However, what we when searching for the previous match
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* is different: we want the node that has a start prior
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* to the cursorIdx.
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* This information cannot be retrieved with 100% accuracy
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* using the `sizes` vector.
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* To get what we want, we recurse downwards using the `sizes` vector.
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* If we found the node we want, we return it.
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* Otherwise, we return a state meaning "no node at this position"
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* and we use the call stack to descend down the node at the previous index.
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* There might not be a previous index because the current index is 0.
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* In this case, either the call stack will handle it,
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* or the caller to `helpPrevMatch` will. *)
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fun helpPrevMatch (cursorIdx, tree, acc) =
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case tree of
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LEAF (values, sizes) =>
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let
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val idx = BinSearch.equalOrMore (cursorIdx, sizes)
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in
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if idx < 0 then
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{start = ~1, finish = ~1}
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else if idx = 0 then
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let
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val result = Vector.sub (values, 0)
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in
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if #start result < cursorIdx then
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{start = #start result + acc, finish = #finish result + acc}
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else
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{start = ~1, finish = ~1}
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end
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else
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let
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val current = Vector.sub (values, idx)
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val {start, finish} =
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if cursorIdx > #start current then current
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else Vector.sub (values, idx - 1)
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in
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{start = start + acc, finish = finish + acc}
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end
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end
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| BRANCH (nodes, sizes) =>
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let
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val idx = BinSearch.equalOrMore (cursorIdx, sizes)
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in
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if idx < 0 then
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{start = ~1, finish = ~1}
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else if idx = 0 then
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helpPrevMatch (cursorIdx, Vector.sub (nodes, idx), acc)
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else
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let
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val node = Vector.sub (nodes, idx)
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val prevSize = Vector.sub (sizes, idx - 1)
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val result =
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helpPrevMatch (cursorIdx - prevSize, node, acc + prevSize)
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in
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if #start result = ~1 then
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let
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val prevPrevSize =
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if idx - 2 < 0 then 0 else Vector.sub (sizes, idx - 2)
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in
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getLast (Vector.sub (nodes, idx - 1), acc + prevPrevSize)
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end
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else
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result
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end
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end
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fun loopPrevMatch (prevStart, prevFinish, tree, count) =
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if count = 0 then
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prevStart
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else
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let
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val {start, finish} = helpPrevMatch (prevFinish - 1, tree, 0)
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in
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if start = ~1 then
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let val {start, finish} = getLast (tree, ~1)
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in loopPrevMatch (start, finish, tree, count - 1)
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end
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else
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loopPrevMatch (start, finish, tree, count - 1)
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end
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fun prevMatch (cursorIdx, tree, count) =
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if isEmpty tree then
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~1
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else
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let
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val {start, finish} = helpPrevMatch (cursorIdx, tree, 0)
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in
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if start = ~1 then
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let val {start, finish} = getLast (tree, ~1)
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in loopPrevMatch (start, finish, tree, count - 1)
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end
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else if cursorIdx >= start andalso cursorIdx <= finish then
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loopPrevMatch (start, finish, tree, count)
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else
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loopPrevMatch (start, finish, tree, count - 1)
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end
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fun getMaxSize tree =
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case tree of
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LEAF (_, sizes) => Vector.sub (sizes, Vector.length sizes - 1)
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| BRANCH (_, sizes) => Vector.sub (sizes, Vector.length sizes - 1)
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fun splitLeft (offset, tree) =
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case tree of
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BRANCH (nodes, sizes) =>
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if offset <= Vector.sub (sizes, 0) then
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splitLeft (offset, Vector.sub (nodes, 0))
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else if offset >= Vector.sub (sizes, Vector.length sizes - 1) then
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let
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val prevSize =
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if Vector.length sizes > 1 then
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Vector.sub (sizes, Vector.length sizes - 1)
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else
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0
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val result =
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splitLeft
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(offset - prevSize, Vector.sub (nodes, Vector.length nodes - 1))
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in
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if isEmpty result then
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let
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val len = SOME (Vector.length sizes - 1)
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val sizeSlice = VectorSlice.slice (sizes, 0, len)
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val sizes = VectorSlice.vector sizeSlice
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val nodeSlice = VectorSlice.slice (nodes, 0, len)
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val nodes = VectorSlice.vector nodeSlice
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in
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BRANCH (nodes, sizes)
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end
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else
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let
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val newChildSize = getMaxSize result + prevSize
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val sizes = Vector.update (sizes, Vector.length sizes - 1, newChildSize)
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val nodes = Vector.update (nodes, Vector.length nodes - 1, result)
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in
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BRANCH (nodes, sizes)
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end
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end
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else
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let
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val idx = BinSearch.equalOrMore (offset, sizes)
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val prevSize =
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if idx > 1 then
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Vector.sub (sizes, idx - 1)
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else
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0
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val result = splitLeft (offset - prevSize, Vector.sub (nodes, idx))
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in
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if isEmpty result then
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let
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val len = SOME idx
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val sizeSlice = VectorSlice.slice (sizes, 0, len)
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val sizes = VectorSlice.vector sizeSlice
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val nodeSlice = VectorSlice.slice (nodes, 0, len)
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val nodes = VectorSlice.vector nodeSlice
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in
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BRANCH (nodes, sizes)
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end
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else
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let
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val len = idx + 1
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val sizes = Vector.tabulate (len,
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fn i =>
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if i = idx then
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getMaxSize result + prevSize
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else
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Vector.sub (sizes, i)
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)
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val nodes = Vector.tabulate (lane,
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fn i =>
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if i = idx then
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result
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else
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Vector.sub (nodes, i)
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)
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in
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BRANCH (nodes, sizes)
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end
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end
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| LEAF (items, sizes) =>
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if Vector.length sizes > 0 then
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if offset > Vector.sub (sizes, Vector.length sizes - 1) then
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tree
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else if offset <= Vector.sub (sizes, 0) then
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LEAF (#[], #[])
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else
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let
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val len = BinSearch.equalOrMore (offset, sizes)
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val sizes = VectorSlice.slice (sizes, 0, SOME len)
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val sizes = VectorSlice.vector sizes
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val items = VectorSlice.slice (items, 0, SOME len)
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val items = VectorSlice.vector items
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in
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LEAF (items, sizes)
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end
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else
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tree
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(* Unlike 'splitLeft' which leaves the size metadata alone
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* (except for splitting it),
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* we want splitRight to decrement the size metadata
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* by the largest entry in the size table that was split.
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* This is so that we can maintain relative indexing metadata. *)
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fun splitRight (offset, tree) =
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case tree of
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BRANCH (nodes, sizes) =>
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if offset <= Vector.sub (sizes, 0) then
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let
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val firstSizeBefore = Vector.sub (sizes, 0)
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val result = splitRight (offset, Vector.sub (nodes, 0))
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in
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if isEmpty result then
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let
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val len = Vector.length sizes - 1
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val sizeSlice = VectorSlice.slice (sizes, 1, SOME len)
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val sizes = VectorSlice.map (fn el => el - firstSizeBefore) sizeSlice
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val nodeSlice = VectorSlice.slice (nodes, 1, SOME len)
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val nodes = VectorSlice.vector nodeSlice
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in
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BRANCH (nodes, sizes)
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end
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else
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let
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val firstSizeAfter = getMaxSize result
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val sizeDiff = firstSizeBefore - firstSizeAfter
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val sizes = Vector.mapi (fn (idx, el) =>
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if idx = 0 then
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firstSizeAfter
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else
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el - sizeDiff
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) sizes
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val nodes = Vector.update (nodes, 0, result)
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in
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BRANCH (nodes, sizes)
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end
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else if offset >= Vector.sub (sizes, Vector.length sizes - 1) then
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let
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val prevSize =
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if Vector.length sizes > 1 then
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Vector.sub (sizes, Vector.length sizes - 2)
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else
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0
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val node = Vector.sub (nodes, Vector.length nodes - 1)
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val result = splitRight (offset - prevSize, node))
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in
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if isEmpty result then
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result
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else
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let
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val len = Vector.length sizes - idx
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val sizeSlice = VectorSlice.slice (sizes, idx, SOME len)
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val sizes = VectorSlice.map (fn el => el - prevSize) sizeSlice
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val nodeSlice = VectorSlice.slice (nodes, idx, SOME len)
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val nodes = VectorSlice.vector nodeSlice
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in
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BRANCH (nodes, sizes)
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end
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end
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else
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| LEAF (items, sizes) =>
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if offset > Vector.sub (sizes, Vector.length sizes - 1) then
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LEAF (#[], #[])
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else if offset <= Vector.sub (sizes, 0) then
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tree
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else
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let
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val idx = BinSearch.equalOrMore (offset, sizes)
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val len = Vector.length sizes - idx
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val len = SOME len
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val prevSize =
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if idx < 1 then
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0
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else
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Vector.sub (sizes, idx - 1)
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val sizes = VectorSlice.slice (sizes, idx, len)
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val sizes = VectorSlice.map (fn i => i - prevSize) sizes
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val items = VectorSlice.slice (items, idx, len)
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val items =
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VectorSlice.map
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(fn {start, finish} =>
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{start = start - prevSize, finish = finish - prevSize})
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items
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in
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LEAF (items, sizes)
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end
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end
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