module Data.Sequence.IdMap
( Seq
, empty
, singleton
, (<|)
, (|>)
, (><)
, fromList
, toList
, viewr
, ViewR (..)
, viewl
, ViewL (..)
) where
import Data.IdMap hiding (insert)
import qualified Data.IdMap as M
import qualified Data.List as List
import Prelude hiding (last)
data Seq a
= forall k . Seq
{ first :: Id k
, last :: Id k
, prev :: !(Map I0 k (Id k))
, next :: !(Map I1 k (Id k))
, value :: !(Map I2 k a)
}
| Empty
empty :: Seq a
empty = Empty
singleton :: forall a. a -> Seq a
singleton a = runICC f where
f :: ICC I2 v (Seq a)
f (v `PlusMap` n `PlusMap` _) p (i:_) = Seq
{ first = i
, last = i
, prev = p
, next = n
, value = M.insert i a v
}
(><) :: Seq a -> Seq a -> Seq a
Empty >< x = x
x >< Empty = x
(Seq f l p n v) >< (Seq f' l' p' n' v')
= Seq
{ first = left f
, last = right l'
, prev = M.insert (right f') (left l) $ fmap left p `union` fmap right p'
, next = M.insert (left l) (right f') $ fmap left n `union` fmap right n'
, value = v `union` v'
}
(<|) :: a -> Seq a -> Seq a
a <| x = singleton a >< x
(|>) :: Seq a -> a -> Seq a
x |> a = x >< singleton a
data ViewR a
= EmptyR
| Seq a :> !a
viewr :: Seq a -> ViewR a
viewr Empty = EmptyR
viewr (Seq f l p n v) = s' :> vl where
vl = v M.! l
s' = case lookUp l p of
Nothing -> Empty
Just pl -> Seq
{ first = f
, last = pl
, prev = p
, next = M.delete pl n
, value = v
}
data ViewL a
= EmptyL
| !a :< Seq a
viewl :: Seq a -> ViewL a
viewl Empty = EmptyL
viewl (Seq f l p n v) = vf :< s' where
vf = v M.! f
s' = case lookUp f n of
Nothing -> Empty
Just nf -> Seq
{ first = nf
, last = l
, prev = M.delete nf p
, next = n
, value = v
}
toList :: Seq a -> [a]
toList s = case viewl s of
EmptyL -> []
a :< ss -> a: toList ss
fromList :: [a] -> Seq a
fromList l = List.foldl' (|>) empty l