Generate Emoji module with TH.

- Add Text.Pandoc.Emoji.TH.
- Replace long literal list in Text.Pandoc.Emoji with one-liner
  generating it from data/emoji.json using TH.
- Add Makefile target to download data/emoji.json.
- Remove tools/emoji.hs.

1 files changed, 40 insertions, 0 deletions

diff --git a/src/Text/Pandoc/Emoji/TH.hs b/src/Text/Pandoc/Emoji/TH.hs
new file mode 100644
index 000000000..a2e11e430
--- /dev/null
+++ b/src/Text/Pandoc/Emoji/TH.hs
@@ -0,0 +1,40 @@
+{-# LANGUAGE ScopedTypeVariables #-}
+{-# LANGUAGE OverloadedStrings #-}
+{- |
+   Module      : Text.Pandoc.Emoji.TH
+   Copyright   : Copyright (C) 2019 John MacFarlane
+   License     : GNU GPL, version 2 or above
+
+   Maintainer  : John MacFarlane <jgm@berkeley.edu>
+   Stability   : alpha
+   Portability : portable
+
+Code generation for emoji list in Text.Pandoc.Emoji.
+-}
+module Text.Pandoc.Emoji.TH ( genEmojis ) where
+import Prelude
+import Data.Aeson
+import qualified Data.ByteString.Lazy as B
+import Language.Haskell.TH
+import Language.Haskell.TH.Syntax (addDependentFile)
+
+genEmojis :: FilePath -> Q Exp
+genEmojis fp = do
+  addDependentFile fp
+  bs <- runIO $ B.readFile fp
+  case eitherDecode bs of
+    Left e -> error e
+    Right (emoji :: [Emoji]) ->
+      return $ ListE
+           [TupE [ LitE (StringL alias),
+                   LitE (StringL txt) ]
+            | Emoji txt aliases <- emoji
+            , alias <- aliases]
+
+data Emoji = Emoji String [String]
+  deriving Show
+
+instance FromJSON Emoji where
+    parseJSON = withObject "Emoji" $ \v -> Emoji
+        <$> v .: "emoji"
+        <*> v .: "aliases"