Merge pull request #300 from ohbadiah/master

matchMetadata for examining metadata when defining rules

1 files changed, 14 insertions, 3 deletions

diff --git a/src/Hakyll/Core/Rules.hs b/src/Hakyll/Core/Rules.hs
index 1b1e4ae..14befde 100644
--- a/src/Hakyll/Core/Rules.hs
+++ b/src/Hakyll/Core/Rules.hs
@@ -19,6 +19,7 @@
 module Hakyll.Core.Rules
     ( Rules
     , match
+    , matchMetadata
     , create
     , version
     , compile
@@ -120,16 +121,26 @@ flush = Rules $ do
 
 
 --------------------------------------------------------------------------------
-match :: Pattern -> Rules () -> Rules ()
-match pattern rules = do
+matchInternal :: Pattern -> Rules [Identifier] -> Rules () -> Rules ()
+matchInternal pattern getIDs rules = do
     tellPattern pattern
     flush
-    ids <- getMatches pattern
+    ids <- getIDs
     tellResources ids
     Rules $ local (setMatches ids) $ unRules $ rules >> flush
   where
     setMatches ids env = env {rulesMatches = ids}
 
+--------------------------------------------------------------------------------
+match :: Pattern -> Rules () -> Rules ()
+match pattern = matchInternal pattern $ getMatches pattern
+
+
+--------------------------------------------------------------------------------
+matchMetadata :: Pattern -> (Metadata -> Bool) -> Rules () -> Rules ()
+matchMetadata pattern metadataPred = matchInternal pattern $
+    map fst . filter (metadataPred . snd) <$> getAllMetadata pattern
+
 
 --------------------------------------------------------------------------------
 create :: [Identifier] -> Rules () -> Rules ()