From 244dae8da8d4bfbf3d5d7e22eacba6092789d841 Mon Sep 17 00:00:00 2001
From: John MacFarlane <jgm@berkeley.edu>
Date: Thu, 9 Aug 2012 07:42:40 -0700
Subject: Added parseFormatSpec to Text.Pandoc.

---
 src/Text/Pandoc.hs | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

(limited to 'src/Text')

diff --git a/src/Text/Pandoc.hs b/src/Text/Pandoc.hs
index e12aa055c..b65e7130d 100644
--- a/src/Text/Pandoc.hs
+++ b/src/Text/Pandoc.hs
@@ -138,12 +138,34 @@ import Text.Pandoc.Options
 import Data.ByteString.Lazy (ByteString)
 import Data.Version (showVersion)
 import Text.JSON.Generic
+import Data.Set (Set)
+import qualified Data.Set as Set
+import Text.Parsec
 import Paths_pandoc (version)
 
 -- | Version number of pandoc library.
 pandocVersion :: String
 pandocVersion = showVersion version
 
+parseFormatSpec :: String
+                -> Either ParseError (String, Set Extension -> Set Extension)
+parseFormatSpec = parse formatSpec ""
+  where formatSpec = do
+          name <- formatName
+          extMods <- many extMod
+          return (name, foldl (.) id extMods)
+        formatName = many1 $ noneOf "-+"
+        extMod = do
+          polarity <- oneOf "-+"
+          name <- many1 $ noneOf "-+"
+          ext <- case reads name of
+                       ((n,[]):_) -> return n
+                       _          -> unexpected $ "Unknown extension: " ++
+                                        name
+          return $ case polarity of
+                        '-'  -> Set.delete ext
+                        _    -> Set.insert ext
+
 -- | Association list of formats and readers.
 readers :: [(String, ReaderOptions -> String -> Pandoc)]
 readers = [("native"       , \_ -> readNative)
-- 
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