[commit: ghc] : Add syntactic support for typed expression brackets and splices. (431849e)

[Geoffrey Mainland]

Repository : http://darcs.haskell.org/ghc.git/

On branch  : 

https://github.com/ghc/ghc/commit/431849eab673dc2550b016dc358a6e0e4f88d25d

>---------------------------------------------------------------

commit 431849eab673dc2550b016dc358a6e0e4f88d25d
Author: Geoffrey Mainland <mainland at apeiron.net>
Date:   Wed Apr 24 13:57:35 2013 +0100

    Add syntactic support for typed expression brackets and splices.
    
    Right now the syntax for typed expression brackets and splices maps to
    conventional brackets and splices, i.e., they are not typed.

>---------------------------------------------------------------

 compiler/parser/Lexer.x     | 47 +++++++++++++++++++++++++++++----------------
 compiler/parser/Parser.y.pp | 10 ++++++++++
 2 files changed, 40 insertions(+), 17 deletions(-)

diff --git a/compiler/parser/Lexer.x b/compiler/parser/Lexer.x
index 6871210..7e41b15 100644
--- a/compiler/parser/Lexer.x
+++ b/compiler/parser/Lexer.x
@@ -307,14 +307,18 @@ $tab+         { warn Opt_WarnTabs (text "Tab character") }
 }
 
 <0> {
-  "[|"      / { ifExtension thEnabled } { token ITopenExpQuote }
-  "[e|"     / { ifExtension thEnabled } { token ITopenExpQuote }
-  "[p|"     / { ifExtension thEnabled } { token ITopenPatQuote }
-  "[d|"     / { ifExtension thEnabled } { layout_token ITopenDecQuote }
-  "[t|"     / { ifExtension thEnabled } { token ITopenTypQuote }
-  "|]"      / { ifExtension thEnabled } { token ITcloseQuote }
-  \$ @varid / { ifExtension thEnabled } { skip_one_varid ITidEscape }
-  "$("      / { ifExtension thEnabled } { token ITparenEscape }
+  "[|"        / { ifExtension thEnabled } { token ITopenExpQuote }
+  "[||"       / { ifExtension thEnabled } { token ITopenTExpQuote }
+  "[e|"       / { ifExtension thEnabled } { token ITopenExpQuote }
+  "[p|"       / { ifExtension thEnabled } { token ITopenPatQuote }
+  "[d|"       / { ifExtension thEnabled } { layout_token ITopenDecQuote }
+  "[t|"       / { ifExtension thEnabled } { token ITopenTypQuote }
+  "|]"        / { ifExtension thEnabled } { token ITcloseQuote }
+  "||]"       / { ifExtension thEnabled } { token ITcloseTExpQuote }
+  \$ @varid   / { ifExtension thEnabled } { skip_one_varid ITidEscape }
+  "$$" @varid / { ifExtension thEnabled } { skip_two_varid ITidTyEscape }
+  "$("        / { ifExtension thEnabled } { token ITparenEscape }
+  "$$("       / { ifExtension thEnabled } { token ITparenTyEscape }
 
 -- For backward compatibility, accept the old dollar syntax
   "[$" @varid "|"  / { ifExtension qqEnabled }
@@ -565,8 +569,12 @@ data Token
   | ITopenDecQuote              --  [d|
   | ITopenTypQuote              --  [t|
   | ITcloseQuote                --  |]
+  | ITopenTExpQuote             --  [||
+  | ITcloseTExpQuote            --  ||]
   | ITidEscape   FastString     --  $x
   | ITparenEscape               --  $(
+  | ITidTyEscape   FastString   --  $$x
+  | ITparenTyEscape             --  $$(
   | ITtyQuote                   --  ''
   | ITquasiQuote (FastString,FastString,RealSrcSpan)
     -- ITquasiQuote(quoter, quote, loc)
@@ -732,6 +740,10 @@ skip_one_varid :: (FastString -> Token) -> Action
 skip_one_varid f span buf len
   = return (L span $! f (lexemeToFastString (stepOn buf) (len-1)))
 
+skip_two_varid :: (FastString -> Token) -> Action
+skip_two_varid f span buf len
+  = return (L span $! f (lexemeToFastString (stepOn (stepOn buf)) (len-2)))
+
 strtoken :: (String -> Token) -> Action
 strtoken f span buf len =
   return (L span $! (f $! lexemeToString buf len))
@@ -2253,16 +2265,17 @@ transitionalAlternativeLayoutWarning msg
    $$ text msg
 
 isALRopen :: Token -> Bool
-isALRopen ITcase        = True
-isALRopen ITif          = True
-isALRopen ITthen        = True
-isALRopen IToparen      = True
-isALRopen ITobrack      = True
-isALRopen ITocurly      = True
+isALRopen ITcase          = True
+isALRopen ITif            = True
+isALRopen ITthen          = True
+isALRopen IToparen        = True
+isALRopen ITobrack        = True
+isALRopen ITocurly        = True
 -- GHC Extensions:
-isALRopen IToubxparen   = True
-isALRopen ITparenEscape = True
-isALRopen _             = False
+isALRopen IToubxparen     = True
+isALRopen ITparenEscape   = True
+isALRopen ITparenTyEscape = True
+isALRopen _               = False
 
 isALRclose :: Token -> Bool
 isALRclose ITof     = True
diff --git a/compiler/parser/Parser.y.pp b/compiler/parser/Parser.y.pp
index 34c0bc6..285ded6 100644
--- a/compiler/parser/Parser.y.pp
+++ b/compiler/parser/Parser.y.pp
@@ -362,8 +362,12 @@ incorrect.
 '[t|'           { L _ ITopenTypQuote  }      
 '[d|'           { L _ ITopenDecQuote  }      
 '|]'            { L _ ITcloseQuote    }
+'[||'           { L _ ITopenTExpQuote   }
+'||]'           { L _ ITcloseTExpQuote  }
 TH_ID_SPLICE    { L _ (ITidEscape _)  }     -- $x
 '$('            { L _ ITparenEscape   }     -- $( exp )
+TH_ID_TY_SPLICE { L _ (ITidTyEscape _)  }   -- $$x
+'$$('           { L _ ITparenTyEscape   }   -- $$( exp )
 TH_TY_QUOTE     { L _ ITtyQuote       }      -- ''T
 TH_QUASIQUOTE   { L _ (ITquasiQuote _) }
 TH_QQUASIQUOTE  { L _ (ITqQuasiQuote _) }
@@ -1537,6 +1541,10 @@ aexp2   :: { LHsExpr RdrName }
                                         (L1 $ HsVar (mkUnqual varName 
                                                         (getTH_ID_SPLICE $1)))) } 
         | '$(' exp ')'          { LL $ HsSpliceE (mkHsSplice $2) }               
+        | TH_ID_TY_SPLICE       { L1 $ HsSpliceE (mkHsSplice 
+                                        (L1 $ HsVar (mkUnqual varName 
+                                                        (getTH_ID_TY_SPLICE $1)))) } 
+        | '$$(' exp ')'         { LL $ HsSpliceE (mkHsSplice $2) }               
 
 
         | SIMPLEQUOTE  qvar     { LL $ HsBracket (VarBr True  (unLoc $2)) }
@@ -1544,6 +1552,7 @@ aexp2   :: { LHsExpr RdrName }
         | TH_TY_QUOTE tyvar     { LL $ HsBracket (VarBr False (unLoc $2)) }
         | TH_TY_QUOTE gtycon    { LL $ HsBracket (VarBr False (unLoc $2)) }
         | '[|' exp '|]'         { LL $ HsBracket (ExpBr $2) }                       
+        | '[||' exp '||]'       { LL $ HsBracket (ExpBr $2) }                       
         | '[t|' ctype '|]'      { LL $ HsBracket (TypBr $2) }                       
         | '[p|' infixexp '|]'   {% checkPattern empty $2 >>= \p ->
                                         return (LL $ HsBracket (PatBr p)) }
@@ -2165,6 +2174,7 @@ getPRIMWORD     (L _ (ITprimword x)) = x
 getPRIMFLOAT    (L _ (ITprimfloat  x)) = x
 getPRIMDOUBLE   (L _ (ITprimdouble x)) = x
 getTH_ID_SPLICE (L _ (ITidEscape x)) = x
+getTH_ID_TY_SPLICE (L _ (ITidTyEscape x)) = x
 getINLINE       (L _ (ITinline_prag inl conl)) = (inl,conl)
 getSPEC_INLINE  (L _ (ITspec_inline_prag True))  = (Inline,  FunLike)
 getSPEC_INLINE  (L _ (ITspec_inline_prag False)) = (NoInline,FunLike)