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{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE UndecidableInstances #-} -- Wrinkle in Note [Trees That Grow]
-- in module Language.Haskell.Syntax.Extension
{-# LANGUAGE DuplicateRecordFields #-}
{-# LANGUAGE TypeApplications #-}
{-# OPTIONS_GHC -Wno-orphans #-} -- Outputable, OutputableBndrId
{-
(c) The University of Glasgow 2006
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-}
-- | Source-language literals
module GHC.Hs.Lit
( module Language.Haskell.Syntax.Lit
, module GHC.Hs.Lit
) where
import GHC.Prelude
import {-# SOURCE #-} GHC.Hs.Expr( pprExpr )
import GHC.Types.Basic (PprPrec(..), topPrec )
import GHC.Core.Ppr ( {- instance OutputableBndr TyVar -} )
import GHC.Types.SourceText
import GHC.Core.Type
import GHC.Utils.Outputable
import GHC.Hs.Extension
import Language.Haskell.Syntax.Expr ( HsExpr )
import Language.Haskell.Syntax.Extension
import Language.Haskell.Syntax.Lit
{-
************************************************************************
* *
\subsection[HsLit]{Literals}
* *
************************************************************************
-}
type instance XHsChar (GhcPass _) = SourceText
type instance XHsCharPrim (GhcPass _) = SourceText
type instance XHsString (GhcPass _) = SourceText
type instance XHsStringPrim (GhcPass _) = SourceText
type instance XHsInt (GhcPass _) = NoExtField
type instance XHsIntPrim (GhcPass _) = SourceText
type instance XHsWordPrim (GhcPass _) = SourceText
type instance XHsInt64Prim (GhcPass _) = SourceText
type instance XHsWord64Prim (GhcPass _) = SourceText
type instance XHsInteger (GhcPass _) = SourceText
type instance XHsRat (GhcPass _) = NoExtField
type instance XHsFloatPrim (GhcPass _) = NoExtField
type instance XHsDoublePrim (GhcPass _) = NoExtField
type instance XXLit (GhcPass _) = DataConCantHappen
data OverLitRn
= OverLitRn {
ol_rebindable :: Bool, -- Note [ol_rebindable]
ol_from_fun :: LIdP GhcRn -- Note [Overloaded literal witnesses]
}
data OverLitTc
= OverLitTc {
ol_rebindable :: Bool, -- Note [ol_rebindable]
ol_witness :: HsExpr GhcTc, -- Note [Overloaded literal witnesses]
ol_type :: Type }
{-
Note [Overloaded literal witnesses]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
During renaming, the coercion function needed for a given HsOverLit is
resolved according to the current scope and RebindableSyntax (see Note
[ol_rebindable]). The result of this resolution *before* type checking
is the coercion function such as 'fromInteger' or 'fromRational',
stored in the ol_from_fun field of OverLitRn.
*After* type checking, the ol_witness field of the OverLitTc contains
the witness of the literal as HsExpr, such as (fromInteger 3) or
lit_78. This witness should replace the literal. Reason: it allows
commoning up of the fromInteger calls, which wouldn't be possible if
the desugarer made the application.
The ol_type in OverLitTc records the type the overloaded literal is
found to have.
-}
type instance XOverLit GhcPs = NoExtField
type instance XOverLit GhcRn = OverLitRn
type instance XOverLit GhcTc = OverLitTc
pprXOverLit :: GhcPass p -> XOverLit (GhcPass p) -> SDoc
pprXOverLit GhcPs noExt = ppr noExt
pprXOverLit GhcRn OverLitRn{ ol_from_fun = from_fun } = ppr from_fun
pprXOverLit GhcTc OverLitTc{ ol_witness = witness } = pprExpr witness
type instance XXOverLit (GhcPass _) = DataConCantHappen
overLitType :: HsOverLit GhcTc -> Type
overLitType (OverLit OverLitTc{ ol_type = ty } _) = ty
-- | @'hsOverLitNeedsParens' p ol@ returns 'True' if an overloaded literal
-- @ol@ needs to be parenthesized under precedence @p@.
hsOverLitNeedsParens :: PprPrec -> HsOverLit x -> Bool
hsOverLitNeedsParens p (OverLit { ol_val = olv }) = go olv
where
go :: OverLitVal -> Bool
go (HsIntegral x) = p > topPrec && il_neg x
go (HsFractional x) = p > topPrec && fl_neg x
go (HsIsString {}) = False
hsOverLitNeedsParens _ (XOverLit { }) = False
-- | @'hsLitNeedsParens' p l@ returns 'True' if a literal @l@ needs
-- to be parenthesized under precedence @p@.
--
-- See Note [Printing of literals in Core] in GHC.Types.Literal
-- for the reasoning.
hsLitNeedsParens :: PprPrec -> HsLit x -> Bool
hsLitNeedsParens p = go
where
go (HsChar {}) = False
go (HsCharPrim {}) = False
go (HsString {}) = False
go (HsStringPrim {}) = False
go (HsInt _ x) = p > topPrec && il_neg x
go (HsIntPrim {}) = False
go (HsWordPrim {}) = False
go (HsInt64Prim {}) = False
go (HsWord64Prim {}) = False
go (HsInteger _ x _) = p > topPrec && x < 0
go (HsRat _ x _) = p > topPrec && fl_neg x
go (HsFloatPrim {}) = False
go (HsDoublePrim {}) = False
go (XLit _) = False
-- | Convert a literal from one index type to another
convertLit :: HsLit (GhcPass p1) -> HsLit (GhcPass p2)
convertLit (HsChar a x) = HsChar a x
convertLit (HsCharPrim a x) = HsCharPrim a x
convertLit (HsString a x) = HsString a x
convertLit (HsStringPrim a x) = HsStringPrim a x
convertLit (HsInt a x) = HsInt a x
convertLit (HsIntPrim a x) = HsIntPrim a x
convertLit (HsWordPrim a x) = HsWordPrim a x
convertLit (HsInt64Prim a x) = HsInt64Prim a x
convertLit (HsWord64Prim a x) = HsWord64Prim a x
convertLit (HsInteger a x b) = HsInteger a x b
convertLit (HsRat a x b) = HsRat a x b
convertLit (HsFloatPrim a x) = HsFloatPrim a x
convertLit (HsDoublePrim a x) = HsDoublePrim a x
{-
Note [ol_rebindable]
~~~~~~~~~~~~~~~~~~~~
The ol_rebindable field is True if this literal is actually
using rebindable syntax. Specifically:
False iff ol_from_fun / ol_witness is the standard one
True iff ol_from_fun / ol_witness is non-standard
Equivalently it's True if
a) RebindableSyntax is on
b) the witness for fromInteger/fromRational/fromString
that happens to be in scope isn't the standard one
-}
-- Instance specific to GhcPs, need the SourceText
instance Outputable (HsLit (GhcPass p)) where
ppr (HsChar st c) = pprWithSourceText st (pprHsChar c)
ppr (HsCharPrim st c) = pprWithSourceText st (pprPrimChar c)
ppr (HsString st s) = pprWithSourceText st (pprHsString s)
ppr (HsStringPrim st s) = pprWithSourceText st (pprHsBytes s)
ppr (HsInt _ i)
= pprWithSourceText (il_text i) (integer (il_value i))
ppr (HsInteger st i _) = pprWithSourceText st (integer i)
ppr (HsRat _ f _) = ppr f
ppr (HsFloatPrim _ f) = ppr f <> primFloatSuffix
ppr (HsDoublePrim _ d) = ppr d <> primDoubleSuffix
ppr (HsIntPrim st i) = pprWithSourceText st (pprPrimInt i)
ppr (HsWordPrim st w) = pprWithSourceText st (pprPrimWord w)
ppr (HsInt64Prim st i) = pprWithSourceText st (pprPrimInt64 i)
ppr (HsWord64Prim st w) = pprWithSourceText st (pprPrimWord64 w)
-- in debug mode, print the expression that it's resolved to, too
instance OutputableBndrId p
=> Outputable (HsOverLit (GhcPass p)) where
ppr (OverLit {ol_val=val, ol_ext=ext})
= ppr val <+> (whenPprDebug (parens (pprXOverLit (ghcPass @p) ext)))
instance Outputable OverLitVal where
ppr (HsIntegral i) = pprWithSourceText (il_text i) (integer (il_value i))
ppr (HsFractional f) = ppr f
ppr (HsIsString st s) = pprWithSourceText st (pprHsString s)
-- | pmPprHsLit pretty prints literals and is used when pretty printing pattern
-- match warnings. All are printed the same (i.e., without hashes if they are
-- primitive and not wrapped in constructors if they are boxed). This happens
-- mainly for too reasons:
-- * We do not want to expose their internal representation
-- * The warnings become too messy
pmPprHsLit :: HsLit (GhcPass x) -> SDoc
pmPprHsLit (HsChar _ c) = pprHsChar c
pmPprHsLit (HsCharPrim _ c) = pprHsChar c
pmPprHsLit (HsString st s) = pprWithSourceText st (pprHsString s)
pmPprHsLit (HsStringPrim _ s) = pprHsBytes s
pmPprHsLit (HsInt _ i) = integer (il_value i)
pmPprHsLit (HsIntPrim _ i) = integer i
pmPprHsLit (HsWordPrim _ w) = integer w
pmPprHsLit (HsInt64Prim _ i) = integer i
pmPprHsLit (HsWord64Prim _ w) = integer w
pmPprHsLit (HsInteger _ i _) = integer i
pmPprHsLit (HsRat _ f _) = ppr f
pmPprHsLit (HsFloatPrim _ f) = ppr f
pmPprHsLit (HsDoublePrim _ d) = ppr d
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