src\Development\Shake\Rules\OrderOnly.hs

{-# LANGUAGE MultiParamTypeClasses, GeneralizedNewtypeDeriving, DeriveDataTypeable #-}

module Development.Shake.Rules.OrderOnly(
 defaultRuleOrderOnly, orderOnly, orderOnlyBS
 ) where

import Development.Shake.Core
import General.String
import Development.Shake.ByteString
import Development.Shake.Classes
import Development.Shake.Rules.File
import qualified Data.ByteString.Char8 as BS


newtype OrderOnlyQ = OrderOnlyQ BSU
 deriving (Typeable,Eq,Hashable,Binary,NFData)

instance Show OrderOnlyQ where show (OrderOnlyQ x) = unpackU x

newtype OrderOnlyA = OrderOnlyA ()
 deriving (Typeable,Eq,Hashable,Binary,NFData)

instance Show OrderOnlyA where show (OrderOnlyA ()) = "OrderOnly"


instance Rule OrderOnlyQ OrderOnlyA where
 storedValue _ (OrderOnlyQ _) = return $ Just $ OrderOnlyA ()


defaultRuleOrderOnly :: Rules ()
defaultRuleOrderOnly = rule $ \(OrderOnlyQ x) -> Just $ do
 needBS [unpackU_ x]
 return $ OrderOnlyA ()


-- | Define order-only dependencies, these are dependencies that will always
-- be built before continuing, but which aren't dependencies of this action.
-- Mostly useful for defining generated dependencies you think might be real dependencies.
-- If they turn out to be real dependencies, you should add an explicit dependency afterwards.
--
-- @
-- \"source.o\" %> \\out -> do
-- 'orderOnly' [\"header.h\"]
-- () <- 'cmd' \"gcc -c source.c -o source.o -MMD -MF source.m\"
-- 'neededMakefileDependencies' \"source.m\"
-- @
--
-- If @header.h@ is included by @source.c@ then the call to 'needMakefileDependencies' will cause
-- it to be added as a real dependency. If it isn't, then the rule won't rebuild if it changes,
-- and you will have lost some opportunity for parallelism.
orderOnly :: [FilePath] -> Action ()
orderOnly xs = (apply $ map (OrderOnlyQ . packU_ . filepathNormalise . unpackU_ . packU) xs :: Action [OrderOnlyA]) >> return ()


orderOnlyBS :: [BS.ByteString] -> Action ()
orderOnlyBS xs = (apply $ map (OrderOnlyQ . packU_ . filepathNormalise) xs :: Action [OrderOnlyA]) >> return ()