150 lines
3.9 KiB
Standard ML
150 lines
3.9 KiB
Standard ML
signature MAKE_BIN_VEC =
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sig
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type elem
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val l: elem * elem -> bool
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val eq: elem * elem -> bool
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val g: elem * elem -> bool
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end
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signature BIN_VEC =
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sig
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type elem
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val empty: elem vector
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val sub: elem vector * int -> elem
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val contains: elem * elem vector -> bool
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val findInsPos: elem * elem vector -> int
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val insert: elem vector * elem * int -> elem vector
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val delete: elem vector * elem -> elem vector
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end
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functor MakeBinVec(Fn: MAKE_BIN_VEC): BIN_VEC =
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struct
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type elem = Fn.elem
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val empty = Vector.fromList []
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val sub = Vector.sub
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fun reverseLinearSearch (pos, findNum, vec) =
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if pos < 0 then
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~1
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else
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let
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val curNum = Vector.sub (vec, pos)
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in
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if Fn.g (findNum, curNum) then pos + 1
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else reverseLinearSearch (pos - 1, findNum, vec)
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end
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fun forwardLinearSearch (pos, findNum, vec) =
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if pos = Vector.length vec then
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Vector.length vec
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else
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let
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val curNum = Vector.sub (vec, pos)
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in
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if Fn.g (findNum, curNum) then pos
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else forwardLinearSearch (pos + 1, findNum, vec)
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end
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fun helpFindInsPos (findNum, vec, low, high, prevMid) =
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if high >= low then
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let
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val mid = low + ((high - low) div 2)
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val curNum = Vector.sub (vec, mid)
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in
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if Fn.eq (curNum, findNum) then
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mid
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else if Fn.l (curNum, findNum) then
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helpFindInsPos (findNum, vec, mid + 1, high, mid)
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else
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helpFindInsPos (findNum, vec, low, mid - 1, mid)
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end
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else
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let
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val curNum = Vector.sub (vec, prevMid)
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in
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if Fn.l (findNum, curNum) then
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forwardLinearSearch (prevMid, findNum, vec)
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else
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reverseLinearSearch (prevMid, findNum, vec)
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end
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fun findInsPos (findNum, vec) =
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if Vector.length vec = 0 then ~1
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else helpFindInsPos (findNum, vec, 0, Vector.length vec - 1, 0)
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fun helpContains (findNum, vec, low, high) =
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if high >= low then
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let
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val mid = low + ((high - low) div 2)
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val curNum = Vector.sub (vec, mid)
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in
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if Fn.eq (curNum, findNum) then
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true
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else if Fn.l (curNum, findNum) then
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helpContains (findNum, vec, mid + 1, high)
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else
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helpContains (findNum, vec, low, mid - 1)
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end
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else
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false
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fun contains (findNum, vec) =
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if Vector.length vec = 0 then false
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else helpContains (findNum, vec, 0, Vector.length vec - 1)
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(* insPos parameter should be the unmodified result of calling findInsPos.
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* The reason the insert function does not call findInsPos directly is so,
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* if two BinVecs are used (one for keys and another for values like a map)
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* then the insert function can be used for both the key vector and value
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* vector *)
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fun insert (vec, elem, insPos) =
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if insPos < 0 then
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Vector.concat [Vector.fromList [elem], vec]
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else if insPos = Vector.length vec then
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Vector.concat [vec, Vector.fromList [elem]]
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else
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let
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val elem = Vector.fromList [elem]
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val elem = VectorSlice.full elem
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val s2len = Vector.length vec - insPos
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val slice1 = VectorSlice.slice (vec, 0, SOME insPos)
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val slice2 = VectorSlice.slice (vec, insPos, SOME s2len)
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in
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VectorSlice.concat [slice1, elem, slice2]
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end
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fun delete (vec, elem: elem) =
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let
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val insPos = findInsPos (elem, vec)
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in
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if insPos < 0 orelse insPos = Vector.length vec then
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vec
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else
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let
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val slice1 = VectorSlice.slice (vec, 0, SOME insPos)
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val slice2Len = Vector.length vec - insPos - 1
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val slice2 = VectorSlice.slice (vec, insPos + 1, SOME slice2Len)
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in
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VectorSlice.concat [slice1, slice2]
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end
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end
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end
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structure IntSet =
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MakeBinVec
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(struct
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type elem = int
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val l = Int.<
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fun eq (a, b) = a = b
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val g = Int.>
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end)
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