hakyll/src/Hakyll/Core/Compiler.hs
2010-12-30 21:18:55 +01:00

77 lines
2.3 KiB
Haskell

-- | A Compiler manages targets and dependencies between targets.
--
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
module Hakyll.Core.Compiler
( Compiler
, getIdentifier
, getRoute
, getResourceString
, require
, requireAll
) where
import Prelude hiding ((.), id)
import Control.Arrow ((>>>))
import Control.Applicative ((<$>))
import Control.Monad.Reader (ask)
import Control.Monad.Trans (liftIO)
import Control.Category (Category, (.))
import Data.Binary (Binary)
import Data.Typeable (Typeable)
import Hakyll.Core.Identifier
import Hakyll.Core.Identifier.Pattern
import Hakyll.Core.CompiledItem
import Hakyll.Core.Writable
import Hakyll.Core.ResourceProvider
import Hakyll.Core.Compiler.Internal
-- | Get the identifier of the item that is currently being compiled
--
getIdentifier :: Compiler a Identifier
getIdentifier = fromJob $ const $ CompilerM $ compilerIdentifier <$> ask
-- | Get the route we are using for this item
--
getRoute :: Compiler a (Maybe FilePath)
getRoute = fromJob $ const $ CompilerM $ compilerRoute <$> ask
-- | Get the resource we are compiling as a string
--
getResourceString :: Compiler a String
getResourceString = getIdentifier >>> getResourceString'
where
getResourceString' = fromJob $ \id' -> CompilerM $ do
provider <- compilerResourceProvider <$> ask
liftIO $ resourceString provider id'
-- | Require another target. Using this function ensures automatic handling of
-- dependencies
--
require :: (Binary a, Typeable a, Writable a)
=> Identifier
-> (b -> a -> c)
-> Compiler b c
require identifier f =
fromDependencies (const [identifier]) >>> fromJob require'
where
require' x = CompilerM $ do
lookup' <- compilerDependencyLookup <$> ask
return $ f x $ unCompiledItem $ lookup' identifier
-- | Require a number of targets. Using this function ensures automatic handling
-- of dependencies
--
requireAll :: (Binary a, Typeable a, Writable a)
=> Pattern
-> (b -> [a] -> c)
-> Compiler b c
requireAll pattern f =
fromDependencies getDeps >>> fromJob requireAll'
where
getDeps = matches pattern . resourceList
requireAll' x = CompilerM $ do
deps <- getDeps . compilerResourceProvider <$> ask
lookup' <- compilerDependencyLookup <$> ask
return $ f x $ map (unCompiledItem . lookup') deps