From cae572e800b1aac6eeace26b4afe9ec7425abd0f Mon Sep 17 00:00:00 2001
From: Hans-Peter Deifel <hpd@hpdeifel.de>
Date: Sun, 9 Sep 2018 08:55:38 +0200
Subject: [PATCH] Add `toList` and `clear` functions to BlockQueue
These are both useful for testing.
---
src/Data/BlockQueue.hs | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)
diff --git a/src/Data/BlockQueue.hs b/src/Data/BlockQueue.hs
index a60ed88..2d7c21a 100644
--- a/src/Data/BlockQueue.hs
+++ b/src/Data/BlockQueue.hs
@@ -15,11 +15,14 @@ module Data.BlockQueue
, enqueue
, dequeue
, elem
+ , clear
+ , toList
) where
import Prelude hiding (null, elem)
import Control.Monad.ST
+import qualified Data.Foldable as Foldable
import Data.Primitive.MutVar
import Data.Sequence (Seq)
@@ -68,7 +71,7 @@ enqueue q block = unlessM (elem block q) $ do
modifyMutVar (q^.queue) $ \s -> s Seq.|> block
UnboxedV.write (q^.presence) (fromBlock block) True
--- | Read and delete the first element in the queue
+-- | Read and delete the first element in the queue.
--
-- Returns 'Nothing' and doesn't modify the queue if it was empty.
--
@@ -81,8 +84,23 @@ dequeue q = Seq.viewl <$> readMutVar (q^.queue) >>= \case
writeMutVar (q^.queue) rest
return (Just x)
--- | Tests whether an element is in the queue
+-- | Tests whether an element is in the queue.
--
-- Runtime: O(1)
elem :: Block -> BlockQueue s -> ST s Bool
elem (Block block) !q = UnboxedV.read (q^.presence) block
+
+-- | Removes all items from the queue.
+--
+-- Runtime: O(max size of queue)
+clear :: BlockQueue s -> ST s ()
+clear q = do
+ writeMutVar (q^.queue) Seq.empty
+ UnboxedV.set (q^.presence) False
+
+-- | Return a list of currently queued items in the order in which they were
+-- added to the queue.
+--
+-- Runtime: O(n)
+toList :: BlockQueue s -> ST s [Block]
+toList q = Foldable.toList <$> readMutVar (q^.queue)
--
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