36 lines
1.2 KiB
Haskell
36 lines
1.2 KiB
Haskell
-- | Interval-based implementation of preview polling, for the platforms which
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-- are not supported by inotify.
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--
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module Hakyll.Web.Preview.Poll
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( previewPoll
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) where
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import Control.Applicative ((<$>))
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import Control.Concurrent (threadDelay)
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import Control.Monad (when, filterM)
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import System.Time (getClockTime)
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import Data.Set (Set)
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import qualified Data.Set as S
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import System.Directory (getModificationTime, doesFileExist)
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import Hakyll.Core.Configuration
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import Hakyll.Core.Resource
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-- | A preview thread that periodically recompiles the site.
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--
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previewPoll :: HakyllConfiguration -- ^ Configuration
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-> Set Resource -- ^ Resources to watch
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-> IO () -- ^ Action called when something changes
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-> IO () -- ^ Can block forever
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previewPoll _ resources callback = do
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let files = map unResource $ S.toList resources
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time <- getClockTime
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loop files time
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where
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delay = 1000000
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loop files time = do
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threadDelay delay
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files' <- filterM doesFileExist files
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modified <- any (time <) <$> mapM getModificationTime files'
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when (modified || files' /= files) callback
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loop files' =<< getClockTime
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