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Reintroduce Endpoint.

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This commit is contained in:
Rob Rix 2017-06-13 21:52:38 -04:00
parent 15c1c43e4b
commit dfd9f3f0ce
1 changed files with 13 additions and 12 deletions
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25
src/SES/Myers.hs
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@ -6,6 +6,7 @@ module SES.Myers
, EditGraph(..)
, Distance(..)
, Diagonal(..)
, Endpoint(..)
, ses
, MyersState
) where
@ -41,6 +42,7 @@ newtype Distance = Distance { unDistance :: Int }
newtype Diagonal = Diagonal { unDiagonal :: Int }
deriving (Eq, Ix, Ord, Show)
data Endpoint a b = Endpoint { x :: !Int, y :: !Int, script :: !(EditScript a b) }
-- API
@ -66,12 +68,12 @@ runSES eq (EditGraph as bs)
where -- | Search an edit graph for the shortest edit script along a specific diagonal, moving onto a given diagonal from one of its in-bounds adjacent diagonals (if any), and sliding down any diagonal edges eagerly.
searchAlongK (Diagonal k) = do
v <- get
let getK k = let (x, script) = v ! Diagonal k in (x, x - k, script)
prev = getK (pred k)
next = getK (succ k)
(x', _, script) = slideFrom $! if d == 0 || k < negate m || k > n then
let getK k = let (x, script) = v ! Diagonal k in Endpoint x (x - k) script
prev = {-# SCC prev #-} getK (pred k)
next = {-# SCC next #-} getK (succ k)
Endpoint x' _ script = slideFrom $! if d == 0 || k < negate m || k > n then
-- The top-left corner, or otherwise out-of-bounds.
(0, 0, [])
Endpoint 0 0 []
else if k == negate d || k == negate m then
-- The lower/left extent of the search region or edit graph, whichever is smaller.
moveDownFrom next
@ -84,26 +86,25 @@ runSES eq (EditGraph as bs)
else
-- The upper/right extent of the search region or edit graph, whichever is smaller.
moveRightFrom prev
put (v Array.// [(Diagonal k, (x', script))])
put ({-# SCC update #-} v Array.// [(Diagonal k, (x', script))])
return $! if x' >= n && (x' - k) >= m then
Just (script, d)
else
Nothing
where -- | Move downward from a given vertex, inserting the element for the corresponding row.
moveDownFrom (x, y, script) = (x, succ y, if y < m then That (bs ! y) : script else script)
moveDownFrom (Endpoint x y script) = Endpoint x (succ y) (if y < m then That (bs ! y) : script else script)
-- | Move rightward from a given vertex, deleting the element for the corresponding column.
moveRightFrom (x, y, script) = (succ x, y, if x < n then This (as ! x) : script else script)
moveRightFrom (Endpoint x y script) = Endpoint (succ x) y (if x < n then This (as ! x) : script else script)
-- | Slide down any diagonal edges from a given vertex.
slideFrom (x, y, script)
slideFrom (Endpoint x y script)
| x >= 0, x < n
, y >= 0, y < m
, a <- as ! x
, b <- bs ! y
, a `eq` b = slideFrom (succ x, y, These a b : script)
| otherwise = ( x, succ y, script)
x (x, _, _) = x
, a `eq` b = slideFrom (Endpoint (succ x) y (These a b : script))
| otherwise = (Endpoint x (succ y) script)
-- Implementation details