[commit: ghc] wip/th-new: Add syntactic support for typed expression brackets and splices. (24a5bab)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/th-new
Link       : http://ghc.haskell.org/trac/ghc/changeset/24a5bab3d2101a95bf2e6aedc624d48b7101d096/ghc

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

commit 24a5bab3d2101a95bf2e6aedc624d48b7101d096
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.


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

24a5bab3d2101a95bf2e6aedc624d48b7101d096
 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 12389e7..5075bd9 100644
--- a/compiler/parser/Lexer.x
+++ b/compiler/parser/Lexer.x
@@ -309,14 +309,18 @@ $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 }
@@ -575,8 +579,12 @@ 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)
@@ -750,6 +758,10 @@ 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))
@@ -2288,16 +2300,17 @@ 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 f30072c..75981e3 100644
--- a/compiler/parser/Parser.y.pp
+++ b/compiler/parser/Parser.y.pp
@@ -349,8 +349,12 @@ 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   }   -- $$( exp )
 TH_TY_QUOTE     { L _ ITtyQuote       }      -- ''T
 TH_QUASIQUOTE   { L _ (ITquasiQuote _) }
 TH_QQUASIQUOTE  { L _ (ITqQuasiQuote _) }
@@ -1534,6 +1538,10 @@ aexp2   :: { LHsExpr RdrName }
                                         (L1 $ HsVar (mkUnqual varName
                                                         (getTH_ID_SPLICE $1)))) }
         | '$(' exp ')'          { LL $ HsSpliceE (mkHsSplice $2) }
+        | TH_ID_TY_SPLICE       { L1 $ HsSpliceE (mkHsSplice
+                                        (L1 $ HsVar (mkUnqual varName
+                                                        (getTH_ID_TY_SPLICE $1)))) }
+        | '$$(' exp ')'         { LL $ HsSpliceE (mkHsSplice $2) }
 
 
         | SIMPLEQUOTE  qvar     { LL $ HsBracket (VarBr True  (unLoc $2)) }
@@ -1541,6 +1549,7 @@ 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)) }
@@ -2169,6 +2178,7 @@ 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)