43 lines
1.9 KiB
Haskell
43 lines
1.9 KiB
Haskell
module Data.Map.Static.Builder where
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import Data.Static
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import Data.Array.Static.Builder
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import Data.List
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import Data.Ord
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import Data.Bits
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buildStaticMap :: (StaticElement i,StaticElement e,Ord i) => [(i,e)] -> String
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buildStaticMap lst = let step :: Int -> [(i,e)] -> [(Int,(i,e))]
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step n chunk = let ss = findSplitSize (genericLength chunk)
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(h,d:t) = genericSplitAt ss chunk
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in if null chunk
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then []
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else (n,d):((step (n*2) h)++(step (n*2+1) t))
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checkHeap n [] = []
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checkHeap n ((c,x):xs) = if c == n
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then x:checkHeap (n+1) xs
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else error $ "Heap is not consistent: Should be "++show n++" but is "++show c
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uheap = sortBy (comparing fst) (step 1 slst)
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slst = sortBy (comparing fst) lst
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heap = checkHeap 1 $ sortBy (comparing fst) (step 1 slst)
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len = length heap
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in "StaticMap ("++buildStaticArray (1,len) (map fst heap)++") ("++buildStaticArray (1,len) (map snd heap)++")"
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maxSize :: Integer -> Integer
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maxSize d = (floor $ 2^^d) - 1
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treeDepth :: Integer -> Integer
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treeDepth sz = find' [0..]
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where
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find' (x:xs) = if (floor $ 2^^x) > sz
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then x
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else find' xs
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findSplitSize :: Integer -> Integer
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findSplitSize len = let depth = treeDepth len
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free = (maxSize depth) - len
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in if free <= (floor $ 2 ^^ (depth - 2))
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then maxSize (depth - 1)
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else len - (maxSize (depth - 2)) - 1
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