[project @ 1997-01-18 10:03:27 by simonpj]

[ghc-hetmet.git] / ghc / compiler / hsSyn / HsBasic.lhs

diff --git a/ghc/compiler/hsSyn/HsBasic.lhs b/ghc/compiler/hsSyn/HsBasic.lhs
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+%
+% (c) The GRASP/AQUA Project, Glasgow University, 1992-1996
+%
+\section[HsLit]{Abstract syntax: source-language literals}
+
+\begin{code}
+#include "HsVersions.h"
+
+module HsBasic where
+
+IMP_Ubiq(){-uitous-}
+IMPORT_1_3(Ratio(Rational))
+
+import Pretty
+\end{code}
+
+%************************************************************************
+%*                                                                     *
+\subsection[Version]{Module and identifier version numbers}
+%*                                                                     *
+%************************************************************************
+
+\begin{code}
+type Version = Int
+\end{code}
+
+%************************************************************************
+%*                                                                     *
+\subsection[HsLit]{Literals}
+%*                                                                     *
+%************************************************************************
+
+
+\begin{code}
+data HsLit
+  = HsChar         Char        -- characters
+  | HsCharPrim     Char        -- unboxed char literals
+  | HsString       FAST_STRING -- strings
+  | HsStringPrim    FAST_STRING        -- packed string
+
+  | HsInt          Integer     -- integer-looking literals
+  | HsFrac         Rational    -- frac-looking literals
+       -- Up through dict-simplification, HsInt and HsFrac simply
+       -- mean the literal was integral- or fractional-looking; i.e.,
+       -- whether it had an explicit decimal-point in it.  *After*
+       -- dict-simplification, they mean (boxed) "Integer" and
+       -- "Rational" [Ratio Integer], respectively.
+
+       -- Dict-simplification tries to replace such lits w/ more
+       -- specific ones, using the unboxed variants that follow...
+  | HsIntPrim      Integer     -- unboxed Int literals
+  | HsFloatPrim            Rational    -- unboxed Float literals
+  | HsDoublePrim    Rational   -- unboxed Double literals
+
+  | HsLitLit       FAST_STRING -- to pass ``literal literals'' through to C
+                               -- also: "overloaded" type; but
+                               -- must resolve to boxed-primitive!
+                               -- (WDP 94/10)
+\end{code}
+
+\begin{code}
+negLiteral (HsInt  i) = HsInt  (-i)
+negLiteral (HsFrac f) = HsFrac (-f)
+\end{code}
+
+\begin{code}
+instance Outputable HsLit where
+    ppr sty (HsChar c)         = ppStr (show c)
+    ppr sty (HsCharPrim c)     = ppBeside (ppStr (show c)) (ppChar '#')
+    ppr sty (HsString s)       = ppStr (show s)
+    ppr sty (HsStringPrim s)   = ppBeside (ppStr (show s)) (ppChar '#')
+    ppr sty (HsInt i)          = ppInteger i
+    ppr sty (HsFrac f)         = ppRational f
+    ppr sty (HsFloatPrim f)    = ppBeside (ppRational f) (ppChar '#')
+    ppr sty (HsDoublePrim d)   = ppBeside (ppRational d) (ppStr "##")
+    ppr sty (HsIntPrim i)      = ppBeside (ppInteger i) (ppChar '#')
+    ppr sty (HsLitLit s)       = ppBesides [ppStr "``", ppPStr s, ppStr "''"]
+\end{code}
+
+%************************************************************************
+%*                                                                     *
+\subsection[Fixity]{Fixity info}
+%*                                                                     *
+%************************************************************************
+
+\begin{code}
+data Fixity = Fixity Int FixityDirection
+data FixityDirection = InfixL | InfixR | InfixN 
+                    deriving(Eq)
+
+instance Outputable Fixity where
+    ppr sty (Fixity prec dir) = ppBesides [ppr sty dir, ppSP, ppInt prec]
+
+instance Outputable FixityDirection where
+    ppr sty InfixL = ppStr "infixl"
+    ppr sty InfixR = ppStr "infixr"
+    ppr sty InfixN = ppStr "infix"
+
+instance Eq Fixity where               -- Used to determine if two fixities conflict
+  (Fixity p1 dir1) == (Fixity p2 dir2) = p1==p2 && dir1 == dir2
+\end{code}
+