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Extract a common handler for the selection of the diagonal.

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This commit is contained in:
Rob Rix 2017-03-13 15:25:59 -04:00
parent 93116b7f26
commit 99b07c3483
1 changed files with 12 additions and 9 deletions
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21
src/SES/Myers.hs
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@ -118,18 +118,18 @@ decompose myers = let ?callStack = popCallStack callStack in case myers of
<*> for [negate d, negate d + 2 .. d] (searchAlongK graph (EditDistance d) Reverse . Diagonal)
SearchAlongK graph (EditDistance d) direction@Forward (Diagonal k) -> do
forwardEndpoint <- findDPath graph (EditDistance d) direction (Diagonal k)
forwardEndpoint <- findDPath graph (EditDistance d) direction (diagonalFor direction k)
backwardV <- gets backward
let reverseEndpoint = let x = backwardV `at` k in Endpoint x (x - k)
let reverseEndpoint = let x = backwardV `at` diagonalFor direction k in Endpoint x (x - k)
if odd delta && k `inInterval` diagonalInterval direction d && overlaps graph forwardEndpoint reverseEndpoint then
return (done reverseEndpoint forwardEndpoint (editDistance direction d))
else
continue
SearchAlongK graph (EditDistance d) direction@Reverse (Diagonal k) -> do
reverseEndpoint <- findDPath graph (EditDistance d) direction (Diagonal (k + delta))
reverseEndpoint <- findDPath graph (EditDistance d) direction (diagonalFor direction k)
forwardV <- gets forward
let forwardEndpoint = let x = forwardV `at` (k + delta) in Endpoint x (x - k)
let forwardEndpoint = let x = forwardV `at` diagonalFor direction k in Endpoint x (x - k)
if even delta && (k + delta) `inInterval` diagonalInterval direction d && overlaps graph forwardEndpoint reverseEndpoint then
return (done reverseEndpoint forwardEndpoint (editDistance direction d))
else
@ -138,8 +138,8 @@ decompose myers = let ?callStack = popCallStack callStack in case myers of
FindDPath _ (EditDistance d) Forward (Diagonal k) -> do
v <- gets forward
eq <- getEq
let prev = v `at` pred k
let next = v `at` succ k
let prev = v `at` Diagonal (pred k)
let next = v `at` Diagonal (succ k)
let x = if k == negate d || k /= d && prev < next
then next
else succ prev
@ -150,8 +150,8 @@ decompose myers = let ?callStack = popCallStack callStack in case myers of
FindDPath _ (EditDistance d) Reverse (Diagonal k) -> do
v <- gets backward
eq <- getEq
let prev = v `at` pred k
let next = v `at` succ k
let prev = v `at` Diagonal (pred k)
let next = v `at` Diagonal (succ k)
let x = if k == negate d || k /= d && prev < next
then next
else succ prev
@ -166,11 +166,14 @@ decompose myers = let ?callStack = popCallStack callStack in case myers of
delta = n - m
maxD = (m + n) `ceilDiv` 2
at v k = v ! maxD + k
at v (Diagonal k) = v ! maxD + k
diagonalInterval Forward d = (delta - pred d, delta + pred d)
diagonalInterval Reverse d = (negate d, d)
diagonalFor Forward k = Diagonal k
diagonalFor Reverse k = Diagonal (k + delta)
done (Endpoint x y) uv d = Just (Snake (Endpoint (n - x) (m - y)) uv, EditDistance d)
editDistance Forward d = 2 * d - 1
editDistance Reverse d = 2 * d