MinMaxPSQ, takeView is useful for syncing with another data structure.

1 files changed, 11 insertions, 0 deletions

diff --git a/src/Data/MinMaxPSQ.hs b/src/Data/MinMaxPSQ.hs
index a6329175..2b3b17b5 100644
--- a/src/Data/MinMaxPSQ.hs
+++ b/src/Data/MinMaxPSQ.hs
@@ -81,5 +81,16 @@ take !n !q | (size q <= n) = q
            | null q        = q
            | otherwise     = take n $ deleteMax q
 
+-- | Like 'take', except it provides a list deleted bindings.
+takeView :: (PSQKey k, Ord p) => Int -> MinMaxPSQ' k p v -> ( [Binding' k p v], MinMaxPSQ' k p v )
+takeView !n !q | (size q <= n) = ([], q)
+               | null q        = ([], q)
+               | otherwise     = let Just (x,q') = maxView q
+                                     (xs,q'')    = takeView n q'
+                                     ys          = x:xs
+                                 in (ys, ys `seq` q'')
+
+
+
 lookup' :: (PSQKey k, Ord p) => k -> MinMaxPSQ' k p v -> Maybe (p, v)
 lookup' k (MinMaxPSQ q _) = PSQ.lookup k q