module Agda.Utils.Trie
( Trie
, empty, singleton, insert, lookupPath, union
) where
import Control.Applicative hiding (empty)
import Control.Monad (mplus)
import Data.Function
import Data.List (nubBy, sortBy, isPrefixOf)
import Data.Map (Map)
import qualified Data.Map as Map
import Test.QuickCheck
data Trie k v = Trie (Maybe v) (Map k (Trie k v))
deriving Show
empty :: Trie k v
empty = Trie Nothing Map.empty
singleton :: [k] -> v -> Trie k v
singleton [] v = Trie (Just v) Map.empty
singleton (x:xs) v = Trie Nothing $ Map.singleton x (singleton xs v)
union :: Ord k => Trie k v -> Trie k v -> Trie k v
union (Trie v ss) (Trie w ts) =
Trie (v `mplus` w) (Map.unionWith union ss ts)
insert :: Ord k => [k] -> v -> Trie k v -> Trie k v
insert k v t = union (singleton k v) t
lookupPath :: Ord k => [k] -> Trie k v -> [v]
lookupPath xs (Trie v cs) = case xs of
[] -> val v
x : xs -> val v ++ maybe [] (lookupPath xs) (Map.lookup x cs)
where
val = maybe [] (:[])
newtype Key = Key Int
deriving (Eq, Ord)
newtype Val = Val Int
deriving (Eq)
newtype Model = Model [([Key], Val)]
deriving (Eq, Show)
instance Show Key where
show (Key x) = show x
instance Show Val where
show (Val x) = show x
instance Arbitrary Key where
arbitrary = elements $ map Key [1..2]
shrink (Key x) = Key <$> shrink x
instance Arbitrary Val where
arbitrary = elements $ map Val [1..3]
shrink (Val x) = Val <$> shrink x
instance Arbitrary Model where
arbitrary = Model <$> arbitrary
shrink (Model xs) = Model <$> shrink xs
modelToTrie :: Model -> Trie Key Val
modelToTrie (Model xs) = foldr (uncurry insert) empty xs
modelPath :: [Key] -> Model -> [Val]
modelPath ks (Model xs) =
map snd
$ sortBy (compare `on` length . fst)
$ nubBy ((==) `on` fst)
$ filter (flip isPrefixOf ks . fst) xs
prop_path ks m =
collect (length $ modelPath ks m) $
lookupPath ks (modelToTrie m) == modelPath ks m