Add bang patterns

[ghc-hetmet.git] / ghc / compiler / parser / Lexer.x

diff --git a/ghc/compiler/parser/Lexer.x b/ghc/compiler/parser/Lexer.x
index 38908a0..90fbf7a 100644 (file)
--- a/ghc/compiler/parser/Lexer.x
+++ b/ghc/compiler/parser/Lexer.x
@@ -26,7 +26,8 @@ module Lexer (
    P(..), ParseResult(..), getSrcLoc, 
    failLocMsgP, failSpanMsgP, srcParseFail,
    popContext, pushCurrentContext, setLastToken, setSrcLoc,
-   getLexState, popLexState, pushLexState
+   getLexState, popLexState, pushLexState,
+   extension, bangPatEnabled
   ) where
 
 #include "HsVersions.h"
@@ -559,10 +560,13 @@ reservedSymsFM = listToUFM $
        ,(">>-",        ITRarrowtail,   bit arrowsBit)
 
 #if __GLASGOW_HASKELL__ >= 605
-       ,("∀",        ITforall,       bit tvBit)
-       ,("→",   ITrarrow,    0)
-       ,("←",   ITlarrow,    0)
-       ,("⋯",        ITdotdot,       0)
+       ,("λ", ITlam,          bit glaExtsBit)
+       ,("∷",   ITdcolon,       bit glaExtsBit)
+       ,("⇒",   ITdarrow,    bit glaExtsBit)
+       ,("∀",        ITforall,       bit glaExtsBit)
+       ,("→",   ITrarrow,    bit glaExtsBit)
+       ,("←",   ITlarrow,    bit glaExtsBit)
+       ,("⋯",        ITdotdot,       bit glaExtsBit)
 #endif
        ]
 
@@ -1181,7 +1185,7 @@ alexGetChar (AI loc ofs s)
 #if __GLASGOW_HASKELL__ < 605
          = c  -- no Unicode support
 #else
-         | c <= '\x04' = non_graphic
+         | c <= '\x06' = non_graphic
          | c <= '\xff' = c
          | otherwise = 
                case generalCategory c of
@@ -1254,6 +1258,8 @@ arrowsBit  = 4
 thBit     = 5
 ipBit      = 6
 tvBit     = 7  -- Scoped type variables enables 'forall' keyword
+bangPatBit = 8 -- Tells the parser to understand bang-patterns
+               -- (doesn't affect the lexer)
 
 glaExtsEnabled, ffiEnabled, parrEnabled :: Int -> Bool
 glaExtsEnabled flags = testBit flags glaExtsBit
@@ -1263,6 +1269,7 @@ arrowsEnabled  flags = testBit flags arrowsBit
 thEnabled      flags = testBit flags thBit
 ipEnabled      flags = testBit flags ipBit
 tvEnabled      flags = testBit flags tvBit
+bangPatEnabled flags = testBit flags bangPatBit
 
 -- create a parse state
 --
@@ -1287,6 +1294,7 @@ mkPState buf loc flags  =
               .|. thBit      `setBitIf` dopt Opt_TH          flags
               .|. ipBit      `setBitIf` dopt Opt_ImplicitParams flags
               .|. tvBit      `setBitIf` dopt Opt_ScopedTypeVariables flags
+              .|. bangPatBit `setBitIf` dopt Opt_BangPatterns flags
       --
       setBitIf :: Int -> Bool -> Int
       b `setBitIf` cond | cond      = bit b
@@ -1348,7 +1356,7 @@ lexError :: String -> P a
 lexError str = do
   loc <- getSrcLoc
   i@(AI end _ buf) <- getInput
-  reportLexError loc end buf False str
+  reportLexError loc end buf str
 
 -- -----------------------------------------------------------------------------
 -- This is the top-level function: called from the parser each time a
@@ -1370,7 +1378,7 @@ lexToken = do
                  setLastToken span 0
                  return (L span ITeof)
     AlexError (AI loc2 _ buf) -> do 
-       reportLexError loc1 loc2 buf True "lexical error"
+       reportLexError loc1 loc2 buf "lexical error"
     AlexSkip inp2 _ -> do
        setInput inp2
        lexToken
@@ -1381,10 +1389,13 @@ lexToken = do
        span `seq` setLastToken span bytes
        t span buf bytes
 
-reportLexError loc1 loc2 buf is_prev str = 
+-- ToDo: Alex reports the buffer at the start of the erroneous lexeme,
+-- but it would be more informative to report the location where the
+-- error was actually discovered, especially if this is a decoding
+-- error.
+reportLexError loc1 loc2 buf str = 
   let 
-       c | is_prev   = prevChar buf '\0'
-         | otherwise = fst (nextChar buf)
+       c = fst (nextChar buf)
   in
   if c == '\0' -- decoding errors are mapped to '\0', see utf8DecodeChar#
     then failLocMsgP loc2 loc2 "UTF-8 decoding error"