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Redefine MyersState as a type synonym.

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This commit is contained in:
Rob Rix 2017-06-13 18:05:56 -04:00
parent a74c0665fd
commit 088df05b73
1 changed files with 5 additions and 11 deletions
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16
src/SES/Myers.hs
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@ -8,7 +8,7 @@ module SES.Myers
, Diagonal(..)
, Endpoint(..)
, ses
, MyersState(..)
, MyersState
) where
import Data.Array ((!))
@ -82,7 +82,7 @@ runSES eq (EditGraph as bs)
-- | Move onto a given diagonal from one of its in-bounds adjacent diagonals (if any), and slide down any diagonal edges eagerly.
moveFromAdjacent (Distance d) (Diagonal k) = do
v <- gets unMyersState
v <- get
let getK k = let (x, script) = v ! k in Endpoint x (x - unDiagonal k) script
let (n, m) = (length as, length bs)
from <- if d == 0 || k < negate m || k > n then
@ -104,7 +104,7 @@ runSES eq (EditGraph as bs)
return (moveRightFrom (getK (Diagonal (pred k))))
endpoint <- slideFrom from
let Endpoint x _ script = endpoint
put (MyersState (v Array.// [(Diagonal k, (x, script))]))
put (v Array.// [(Diagonal k, (x, script))])
return endpoint
-- | Move downward from a given vertex, inserting the element for the corresponding row.
@ -126,13 +126,12 @@ runSES eq (EditGraph as bs)
-- Implementation details
-- | The state stored by Myers’ algorithm; an array of m + n + 1 values indicating the maximum x-index reached and path taken along each diagonal.
newtype MyersState a b = MyersState { unMyersState :: Array.Array Diagonal (Int, EditScript a b) }
deriving (Eq, Show)
type MyersState a b = Array.Array Diagonal (Int, EditScript a b)
-- | Compute the empty state of length m + n + 1 for a given edit graph.
emptyStateForGraph :: EditGraph a b -> MyersState a b
emptyStateForGraph (EditGraph as bs) = let (n, m) = (length as, length bs) in
MyersState (Array.listArray (Diagonal (negate m), Diagonal n) (repeat (0, [])))
Array.listArray (Diagonal (negate m), Diagonal n) (repeat (0, []))
-- | Evaluate some function for each value in a list until one returns a value or the list is exhausted.
for :: [a] -> (a -> Myers c d (Maybe b)) -> Myers c d (Maybe b)
@ -168,11 +167,6 @@ liftShowsEndpoint sp1 sp2 d (Endpoint x y script) = showsTernaryWith showsPrec s
-- Instances
instance Show2 MyersState where
liftShowsPrec2 sp1 _ sp2 _ d (MyersState v) = showsUnaryWith showsStateVector "MyersState" d v
where showsStateVector = showsWith liftShowsVector (showsWith liftShowsPrec (liftShowsEditScript sp1 sp2))
showsWith g f = g f (showListWith (f 0))
instance Show2 EditGraph where
liftShowsPrec2 sp1 sl1 sp2 sl2 d (EditGraph as bs) = showsBinaryWith (liftShowsVector sp1 sl1) (liftShowsVector sp2 sl2) "EditGraph" d as bs