From 9331d3a35c2d370a974dced5515d2e4357ec0d6f Mon Sep 17 00:00:00 2001
From: Simon Marlow <marlowsd@gmail.com>
Date: Thu, 11 Aug 2011 12:08:15 +0100
Subject: Hack this to make it work with both Alex 2.x and Alex 3.x.  Unicode
 in documentation strings is (still) mangled.  I don't think it's possible to
 make it so that we get the current behaviour with Alex 2.x but magic Unicode
 support if you use Alex 3.x.  At some point we have to decide that Alex 3.x
 is a requirement, then we can do Unicode.

---
 src/Haddock/Lex.x | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/Haddock/Lex.x b/src/Haddock/Lex.x
index 17267656..e41c9461 100644
--- a/src/Haddock/Lex.x
+++ b/src/Haddock/Lex.x
@@ -31,12 +31,11 @@ import DynFlags
 import FastString
 
 import Data.Char
+import Data.Word (Word8)
 import Numeric
 import System.IO.Unsafe
 }
 
-%wrapper "posn"
-
 $ws    = $white # \n
 $digit = [0-9]
 $hexdigit = [0-9a-fA-F]
@@ -140,6 +139,37 @@ tokenPos t = let AlexPn _ line col = snd t in (line, col)
 -- -----------------------------------------------------------------------------
 -- Alex support stuff
 
+-- XXX: copied the posn wrapper code from Alex to make this lexer work
+-- with both Alex 2.x and Alex 3.x.  However, we are not using the
+-- Unicode/UTF-8 support in Alex 3.x, and Unicode documentation will
+-- probably get mangled.
+
+type AlexInput = (AlexPosn,     -- current position,
+                  Char,         -- previous char
+                  String)       -- current input string
+
+alexInputPrevChar :: AlexInput -> Char
+alexInputPrevChar (p,c,s) = c
+
+alexGetByte :: AlexInput -> Maybe (Word8,AlexInput)
+alexGetByte (p,c,[]) = Nothing
+alexGetByte (p,_,(c:s))  = let p' = alexMove p c
+                              in p' `seq`  Just (fromIntegral (ord c), (p', c, s))
+
+-- for compat with Alex 2.x:
+alexGetChar :: AlexInput -> Maybe (Char,AlexInput)
+alexGetChar i = case alexGetByte i of
+                  Nothing     -> Nothing
+                  Just (b,i') -> Just (chr (fromIntegral b), i')
+
+alexMove :: AlexPosn -> Char -> AlexPosn
+alexMove (AlexPn a l c) '\t' = AlexPn (a+1)  l     (((c+7) `div` 8)*8+1)
+alexMove (AlexPn a l c) '\n' = AlexPn (a+1) (l+1)   1
+alexMove (AlexPn a l c) _    = AlexPn (a+1)  l     (c+1)
+
+data AlexPosn = AlexPn !Int !Int !Int
+        deriving (Eq,Show)
+
 type StartCode = Int
 type Action = AlexPosn -> String -> StartCode -> (StartCode -> [LToken]) -> DynFlags -> [LToken]
 
-- 
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