@@ -19,6 +19,7 @@
1919module Data.FileEmbed
2020 ( -- * Embed at compile time
2121 embedFile
22+ , embedFileIfExists
2223 , embedOneFileOf
2324 , embedDir
2425 , embedDirListing
@@ -38,6 +39,7 @@ module Data.FileEmbed
3839 , injectFileWith
3940 -- * Relative path manipulation
4041 , makeRelativeToProject
42+ , makeRelativeToLocationPredicate
4143 -- * Internal
4244 , stringToBs
4345 , bsToExp
@@ -60,13 +62,14 @@ import qualified Data.ByteString.Internal as B
6062#endif
6163import System.Directory (doesDirectoryExist, doesFileExist,
6264 getDirectoryContents, canonicalizePath)
63−import Control.Exception (throw, ErrorCall(..))
64−import Control.Monad (filterM)
65+import Control.Exception (throw, tryJust, ErrorCall(..))
66+import Control.Monad (filterM, guard)
6567import qualified Data.ByteString as B
6668import qualified Data.ByteString.Char8 as B8
6769import Control.Arrow ((&&&), second)
6870import Control.Applicative ((<$>))
6971import Data.ByteString.Unsafe (unsafePackAddressLen)
72+import System.IO.Error (isDoesNotExistError)
7073import System.IO.Unsafe (unsafePerformIO)
7174import System.FilePath ((</>), takeDirectory, takeExtension)
7275import Data.String (fromString)
@@ -87,6 +90,33 @@ embedFile fp =
8790#endif
8891 (runIO $ B.readFile fp) >>= bsToExp
8992
93+-- | Maybe embed a single file in your source code depending on whether or not file exists.
94+--
95+-- Warning: When a build is compiled with the file missing, a recompile when the file exists might not trigger an embed of the file.
96+-- You might try to fix this by doing a clean build.
97+--
98+-- > import qualified Data.ByteString
99+-- >
100+-- > maybeMyFile :: Maybe Data.ByteString.ByteString
101+-- > maybeMyFile = $(embedFileIfExists "dirName/fileName")
102+--
103+-- @since 0.0.14.0
104+embedFileIfExists :: FilePath -> Q Exp
105+embedFileIfExists fp = do
106+ mbs <- runIO maybeFile
107+ case mbs of
108+ Nothing -> [| Nothing |]
109+ Just bs -> do
110+#if MIN_VERSION_template_haskell(2,7,0)
111+ qAddDependentFile fp
112+#endif
113+ [| Just $(bsToExp bs) |]
114+ where
115+ maybeFile :: IO (Maybe B.ByteString)
116+ maybeFile =
117+ either (const Nothing) Just <$>
118+ tryJust (guard . isDoesNotExistError) (B.readFile fp)
119+
90120-- | Embed a single existing file in your source code
91121-- out of list a list of paths supplied.
92122--
@@ -379,7 +409,19 @@ available, you can use the non-@With@ variants.
379409--
380410-- @since 0.0.10
381411makeRelativeToProject :: FilePath -> Q FilePath
382−makeRelativeToProject rel = do
412+makeRelativeToProject = makeRelativeToLocationPredicate $ (==) ".cabal" . takeExtension
413+
414+-- | Take a predicate to infer the project root and a relative file path, the given file path is then attached to the inferred project root
415+--
416+-- This function looks at the source location of the Haskell file calling it,
417+-- finds the first parent directory with a file matching the given predicate, and uses that as the
418+-- root directory for fixing the relative path.
419+--
420+-- @$(makeRelativeToLocationPredicate ((==) ".cabal" . takeExtension) "data/foo.txt" >>= embedFile)@
421+--
422+-- @since 0.0.15.0
423+makeRelativeToLocationPredicate :: (FilePath -> Bool) -> FilePath -> Q FilePath
424+makeRelativeToLocationPredicate isTargetFile rel = do
383425 loc <- qLocation
384426 runIO $ do
385427 srcFP <- canonicalizePath $ loc_filename loc
@@ -394,8 +436,6 @@ makeRelativeToProject rel = do
394436 then return Nothing
395437 else do
396438 contents <- getDirectoryContents dir
397− if any isCabalFile contents
439+ if any isTargetFile contents
398440 then return (Just dir)
399441 else findProjectDir dir
400−
401− isCabalFile fp = takeExtension fp == ".cabal"