From 44b1d87503a62181b4079962632cd61f1e158d79 Mon Sep 17 00:00:00 2001
From: Alec Theriault <alec.theriault@gmail.com>
Date: Mon, 5 Feb 2018 18:14:32 -0800
Subject: Support unicode operators, proper modules

Unicode operators are a pretty big thing in Haskell, so supporting linking them
seems like it outweighs the cost of the extra machinery to force Attoparsec to
look for unicode.

Fixes #458.
---
 .../src/Documentation/Haddock/Parser/Monad.hs      | 25 ++++++++++++++++++++--
 1 file changed, 23 insertions(+), 2 deletions(-)

(limited to 'haddock-library/src/Documentation/Haddock/Parser')

diff --git a/haddock-library/src/Documentation/Haddock/Parser/Monad.hs b/haddock-library/src/Documentation/Haddock/Parser/Monad.hs
index 3f7d60f8..3430ef8a 100644
--- a/haddock-library/src/Documentation/Haddock/Parser/Monad.hs
+++ b/haddock-library/src/Documentation/Haddock/Parser/Monad.hs
@@ -1,4 +1,4 @@
-{-# LANGUAGE GeneralizedNewtypeDeriving, TypeFamilies #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving, TypeFamilies, BangPatterns #-}
 module Documentation.Haddock.Parser.Monad (
   module Documentation.Haddock.Parser.Monad
 , Attoparsec.isDigit
@@ -31,9 +31,10 @@ module Documentation.Haddock.Parser.Monad (
 import           Control.Applicative
 import           Control.Monad
 import           Data.String
-import           Data.ByteString (ByteString)
+import           Data.ByteString (ByteString, length)
 import qualified Data.ByteString.Lazy as LB
 import qualified Data.Attoparsec.ByteString.Char8 as Attoparsec
+import qualified Data.Attoparsec.Combinator as Attoparsec
 import           Control.Monad.Trans.State
 import qualified Control.Monad.Trans.Class as Trans
 import           Data.Word
@@ -41,6 +42,7 @@ import           Data.Bits
 import           Data.Tuple
 
 import           Documentation.Haddock.Types (Version)
+import           Documentation.Haddock.Utf8  (encodeUtf8, decodeUtf8)
 
 newtype ParserState = ParserState {
   parserStateSince :: Maybe Version
@@ -73,6 +75,25 @@ char = lift . Attoparsec.char
 char8 :: Char -> Parser Word8
 char8 = lift . Attoparsec.char8
 
+-- | Peek a unicode character and return the number of bytes that it took up
+peekUnicode :: Parser (Char, Int)
+peekUnicode = lift $ Attoparsec.lookAhead $ do
+  
+  -- attoparsec's take fails on shorter inputs rather than truncate
+  bs <- Attoparsec.choice (map Attoparsec.take [4,3,2,1])
+  
+  let !c = head . decodeUtf8 $ bs
+      !n = Data.ByteString.length . encodeUtf8 $ [c]
+  pure (c, fromIntegral n)
+
+-- | Like 'satisfy', but consuming a unicode character
+satisfyUnicode :: (Char -> Bool) -> Parser Char
+satisfyUnicode predicate = do
+  (c,n) <- peekUnicode
+  if predicate c
+    then Documentation.Haddock.Parser.Monad.take n *> pure c
+    else fail "satsifyUnicode"
+
 anyChar :: Parser Char
 anyChar = lift Attoparsec.anyChar
 
-- 
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