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|
module Text.Hakyll.RenderAction
( RenderAction (..)
, createRenderAction
, createSimpleRenderAction
, createFileRenderAction
, createManipulationAction
, chain
, runRenderAction
, runRenderActionIfNeeded
, Renderable
) where
import Control.Category
import Control.Monad ((<=<), mplus, unless)
import Control.Monad.Reader (liftIO)
import Prelude hiding ((.), id)
import System.IO (hPutStrLn, stderr)
import Text.Hakyll.Context
import Text.Hakyll.File (toDestination, isFileMoreRecent)
import Text.Hakyll.Hakyll
data RenderAction a b = RenderAction
{ actionDependencies :: [FilePath]
, actionUrl :: Maybe (Hakyll FilePath)
, actionFunction :: a -> Hakyll b
}
createRenderAction :: (a -> Hakyll b) -> RenderAction a b
createRenderAction f = id { actionFunction = f }
createSimpleRenderAction :: Hakyll b -> RenderAction () b
createSimpleRenderAction = createRenderAction . const
createFileRenderAction :: FilePath -> Hakyll b -> RenderAction () b
createFileRenderAction path action = RenderAction
{ actionDependencies = [path]
, actionUrl = Just $ return path
, actionFunction = const action
}
instance Category RenderAction where
id = RenderAction
{ actionDependencies = []
, actionUrl = Nothing
, actionFunction = return
}
x . y = RenderAction
{ actionDependencies = actionDependencies x ++ actionDependencies y
, actionUrl = actionUrl y `mplus` actionUrl x
, actionFunction = actionFunction x <=< actionFunction y
}
createManipulationAction :: ContextManipulation -> RenderAction Context Context
createManipulationAction = createRenderAction . (return .)
chain :: [RenderAction a a] -> RenderAction a a
chain [] = id
chain list@(_:_) = foldl1 (>>>) list
runRenderAction :: RenderAction () a -> Hakyll a
runRenderAction action = actionFunction action ()
runRenderActionIfNeeded :: RenderAction () () -> Hakyll ()
runRenderActionIfNeeded action = do
url <- case actionUrl action of
(Just u) -> u
Nothing -> error "No url when checking dependencies."
destination <- toDestination url
valid <- isFileMoreRecent destination $ actionDependencies action
unless valid $ do liftIO $ hPutStrLn stderr $ "Rendering " ++ destination
runRenderAction action
type Renderable = RenderAction () Context
|
