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-rw-r--r--src/Hakyll/Core/Provider/Metadata.hs37
1 files changed, 31 insertions, 6 deletions
diff --git a/src/Hakyll/Core/Provider/Metadata.hs b/src/Hakyll/Core/Provider/Metadata.hs
index c7fdd55..97dbc9e 100644
--- a/src/Hakyll/Core/Provider/Metadata.hs
+++ b/src/Hakyll/Core/Provider/Metadata.hs
@@ -4,12 +4,15 @@
module Hakyll.Core.Provider.Metadata
( loadMetadata
, parsePage
+
+ , MetadataException (..)
) where
--------------------------------------------------------------------------------
import Control.Applicative
import Control.Arrow (second)
+import Control.Exception (Exception, throwIO)
import Control.Monad (guard)
import qualified Data.ByteString.Char8 as BC
import qualified Data.HashMap.Strict as HMS
@@ -52,7 +55,9 @@ loadMetadata p identifier = do
loadMetadataHeader :: FilePath -> IO (Metadata, String)
loadMetadataHeader fp = do
fileContent <- readFile fp
- either fail return (parsePage fileContent)
+ case parsePage fileContent of
+ Right x -> return x
+ Left err -> throwIO $ MetadataException fp err
--------------------------------------------------------------------------------
@@ -82,11 +87,15 @@ probablyHasMetadataHeader fp = do
splitMetadata :: String -> (Maybe String, String)
splitMetadata str0 = fromMaybe (Nothing, str0) $ do
guard $ leading >= 3
- let !(!meta, !content0) = breakWhen isTrailing (drop leading str0)
+ let !str1 = drop leading str0
+ guard $ all isNewline (take 1 str1)
+ let !(!meta, !content0) = breakWhen isTrailing str1
guard $ not $ null content0
let !content1 = drop (leading + 1) content0
!content2 = dropWhile isNewline $ dropWhile isInlineSpace content1
- return (Just meta, content2)
+ -- Adding this newline fixes the line numbers reported by the YAML parser.
+ -- It's a bit ugly but it works.
+ return (Just ('\n' : meta), content2)
where
-- Parse the leading "---"
!leading = length $ takeWhile (== '-') str0
@@ -103,12 +112,12 @@ splitMetadata str0 = fromMaybe (Nothing, str0) $ do
--------------------------------------------------------------------------------
-parseMetadata :: String -> Either String Metadata
-parseMetadata = Yaml.decodeEither . T.encodeUtf8 . T.pack
+parseMetadata :: String -> Either Yaml.ParseException Metadata
+parseMetadata = Yaml.decodeEither' . T.encodeUtf8 . T.pack
--------------------------------------------------------------------------------
-parsePage :: String -> Either String (Metadata, String)
+parsePage :: String -> Either Yaml.ParseException (Metadata, String)
parsePage fileContent = case mbMetaBlock of
Nothing -> return (mempty, content)
Just metaBlock -> case parseMetadata metaBlock of
@@ -116,3 +125,19 @@ parsePage fileContent = case mbMetaBlock of
Right meta -> return (meta, content)
where
!(!mbMetaBlock, !content) = splitMetadata fileContent
+
+
+--------------------------------------------------------------------------------
+-- | Thrown in the IO monad if things go wrong. Provides a nice-ish error
+-- message.
+data MetadataException = MetadataException FilePath Yaml.ParseException
+
+
+--------------------------------------------------------------------------------
+instance Exception MetadataException
+
+
+--------------------------------------------------------------------------------
+instance Show MetadataException where
+ show (MetadataException fp err) =
+ fp ++ ": " ++ Yaml.prettyPrintParseException err