From 1996052b110b8528e90d76c06e13c0b7e4a2e93a Mon Sep 17 00:00:00 2001
From: Jasper Van der Jeugt <m@jaspervdj.be>
Date: Sun, 19 Feb 2012 20:29:26 +0100
Subject: Add complement function for patterns

---
 src/Hakyll/Core/Identifier/Pattern.hs | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

(limited to 'src/Hakyll/Core/Identifier')

diff --git a/src/Hakyll/Core/Identifier/Pattern.hs b/src/Hakyll/Core/Identifier/Pattern.hs
index e770d13..5f97215 100644
--- a/src/Hakyll/Core/Identifier/Pattern.hs
+++ b/src/Hakyll/Core/Identifier/Pattern.hs
@@ -36,13 +36,19 @@
 -- function.
 --
 module Hakyll.Core.Identifier.Pattern
-    ( Pattern
+    ( -- * The pattern type
+      Pattern
     , castPattern
+
+      -- * Creating patterns
     , parseGlob
     , predicate
     , list
     , regex
     , inGroup
+    , complement
+
+      -- * Applying patterns
     , matches
     , filterMatches
     , capture
@@ -131,6 +137,15 @@ regex str = predicate $ fromMaybe False . (=~~ str) . toFilePath
 inGroup :: Maybe String -> Pattern a
 inGroup group = predicate $ (== group) . identifierGroup
 
+-- | Inverts a pattern, e.g.
+--
+-- > complement "foo/bar.html"
+--
+-- will match /anything/ except @\"foo\/bar.html\"@
+--
+complement :: Pattern a -> Pattern a
+complement p = predicate (not . matches p)
+
 -- | Check if an identifier matches a pattern
 --
 matches :: Pattern a -> Identifier a -> Bool
-- 
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