\begin{code}
-{-# OPTIONS_GHC -fno-implicit-prelude #-}
+{-# LANGUAGE NoImplicitPrelude, BangPatterns, MagicHash #-}
+{-# OPTIONS_HADDOCK hide #-}
+
-----------------------------------------------------------------------------
-- |
-- Module : GHC.Show
-- #hide
module GHC.Show
- (
- Show(..), ShowS,
+ (
+ Show(..), ShowS,
- -- Instances for Show: (), [], Bool, Ordering, Int, Char
+ -- Instances for Show: (), [], Bool, Ordering, Int, Char
- -- Show support code
- shows, showChar, showString, showParen, showList__, showSpace,
- showLitChar, protectEsc,
- intToDigit, showSignedInt,
- appPrec, appPrec1,
+ -- Show support code
+ shows, showChar, showString, showMultiLineString,
+ showParen, showList__, showSpace,
+ showLitChar, showLitString, protectEsc,
+ intToDigit, showSignedInt,
+ appPrec, appPrec1,
- -- Character operations
- asciiTab,
- )
- where
+ -- Character operations
+ asciiTab,
+ )
+ where
-import {-# SOURCE #-} GHC.Err ( error )
import GHC.Base
-import GHC.Enum
import Data.Maybe
-import Data.Either
-import GHC.List ( (!!),
-#ifdef USE_REPORT_PRELUDE
- , concatMap, foldr1
-#endif
- )
+import GHC.List ((!!), foldr1, break)
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{The @Show@ class}
-%* *
+%* *
%*********************************************************
\begin{code}
-- That is, 'Text.Read.readsPrec' parses the string produced by
-- 'showsPrec', and delivers the value that 'showsPrec' started with.
- showsPrec :: Int -- ^ the operator precedence of the enclosing
- -- context (a number from @0@ to @11@).
- -- Function application has precedence @10@.
- -> a -- ^ the value to be converted to a 'String'
- -> ShowS
+ showsPrec :: Int -- ^ the operator precedence of the enclosing
+ -- context (a number from @0@ to @11@).
+ -- Function application has precedence @10@.
+ -> a -- ^ the value to be converted to a 'String'
+ -> ShowS
-- | A specialised variant of 'showsPrec', using precedence context
-- zero, and returning an ordinary 'String'.
showl (y:ys) = ',' : showx y (showl ys)
appPrec, appPrec1 :: Int
- -- Use unboxed stuff because we don't have overloaded numerics yet
-appPrec = I# 10# -- Precedence of application:
- -- one more than the maximum operator precedence of 9
-appPrec1 = I# 11# -- appPrec + 1
+ -- Use unboxed stuff because we don't have overloaded numerics yet
+appPrec = I# 10# -- Precedence of application:
+ -- one more than the maximum operator precedence of 9
+appPrec1 = I# 11# -- appPrec + 1
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{Simple Instances}
-%* *
+%* *
%*********************************************************
\begin{code}
showsPrec _ '\'' = showString "'\\''"
showsPrec _ c = showChar '\'' . showLitChar c . showChar '\''
- showList cs = showChar '"' . showl cs
- where showl "" s = showChar '"' s
- showl ('"':xs) s = showString "\\\"" (showl xs s)
- showl (x:xs) s = showLitChar x (showl xs s)
- -- Making 's' an explicit parameter makes it clear to GHC
- -- that showl has arity 2, which avoids it allocating an extra lambda
- -- The sticking point is the recursive call to (showl xs), which
- -- it can't figure out would be ok with arity 2.
+ showList cs = showChar '"' . showLitString cs . showChar '"'
instance Show Int where
showsPrec = showSignedInt
showsPrec _p Nothing s = showString "Nothing" s
showsPrec p (Just x) s
= (showParen (p > appPrec) $
- showString "Just " .
- showsPrec appPrec1 x) s
-
-instance (Show a, Show b) => Show (Either a b) where
- showsPrec p e s =
- (showParen (p > appPrec) $
- case e of
- Left a -> showString "Left " . showsPrec appPrec1 a
- Right b -> showString "Right " . showsPrec appPrec1 b)
- s
+ showString "Just " .
+ showsPrec appPrec1 x) s
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{Show instances for the first few tuples
-%* *
+%* *
%*********************************************************
\begin{code}
-- The explicit 's' parameters are important
-- Otherwise GHC thinks that "shows x" might take a lot of work to compute
-- and generates defns like
--- showsPrec _ (x,y) = let sx = shows x; sy = shows y in
--- \s -> showChar '(' (sx (showChar ',' (sy (showChar ')' s))))
+-- showsPrec _ (x,y) = let sx = shows x; sy = shows y in
+-- \s -> showChar '(' (sx (showChar ',' (sy (showChar ')' s))))
instance (Show a, Show b) => Show (a,b) where
- showsPrec _ (x,y) s = (showChar '(' . shows x . showChar ',' .
- shows y . showChar ')')
- s
+ showsPrec _ (a,b) s = show_tuple [shows a, shows b] s
instance (Show a, Show b, Show c) => Show (a, b, c) where
- showsPrec _ (x,y,z) s = (showChar '(' . shows x . showChar ',' .
- shows y . showChar ',' .
- shows z . showChar ')')
- s
+ showsPrec _ (a,b,c) s = show_tuple [shows a, shows b, shows c] s
instance (Show a, Show b, Show c, Show d) => Show (a, b, c, d) where
- showsPrec _ (w,x,y,z) s = (showChar '(' . shows w . showChar ',' .
- shows x . showChar ',' .
- shows y . showChar ',' .
- shows z . showChar ')')
- s
+ showsPrec _ (a,b,c,d) s = show_tuple [shows a, shows b, shows c, shows d] s
instance (Show a, Show b, Show c, Show d, Show e) => Show (a, b, c, d, e) where
- showsPrec _ (v,w,x,y,z) s = (showChar '(' . shows v . showChar ',' .
- shows w . showChar ',' .
- shows x . showChar ',' .
- shows y . showChar ',' .
- shows z . showChar ')')
- s
+ showsPrec _ (a,b,c,d,e) s = show_tuple [shows a, shows b, shows c, shows d, shows e] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f) => Show (a,b,c,d,e,f) where
+ showsPrec _ (a,b,c,d,e,f) s = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g)
+ => Show (a,b,c,d,e,f,g) where
+ showsPrec _ (a,b,c,d,e,f,g) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h)
+ => Show (a,b,c,d,e,f,g,h) where
+ showsPrec _ (a,b,c,d,e,f,g,h) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g, shows h] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i)
+ => Show (a,b,c,d,e,f,g,h,i) where
+ showsPrec _ (a,b,c,d,e,f,g,h,i) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g, shows h,
+ shows i] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j)
+ => Show (a,b,c,d,e,f,g,h,i,j) where
+ showsPrec _ (a,b,c,d,e,f,g,h,i,j) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g, shows h,
+ shows i, shows j] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k)
+ => Show (a,b,c,d,e,f,g,h,i,j,k) where
+ showsPrec _ (a,b,c,d,e,f,g,h,i,j,k) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g, shows h,
+ shows i, shows j, shows k] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k,
+ Show l)
+ => Show (a,b,c,d,e,f,g,h,i,j,k,l) where
+ showsPrec _ (a,b,c,d,e,f,g,h,i,j,k,l) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g, shows h,
+ shows i, shows j, shows k, shows l] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k,
+ Show l, Show m)
+ => Show (a,b,c,d,e,f,g,h,i,j,k,l,m) where
+ showsPrec _ (a,b,c,d,e,f,g,h,i,j,k,l,m) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g, shows h,
+ shows i, shows j, shows k, shows l, shows m] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k,
+ Show l, Show m, Show n)
+ => Show (a,b,c,d,e,f,g,h,i,j,k,l,m,n) where
+ showsPrec _ (a,b,c,d,e,f,g,h,i,j,k,l,m,n) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g, shows h,
+ shows i, shows j, shows k, shows l, shows m, shows n] s
+
+instance (Show a, Show b, Show c, Show d, Show e, Show f, Show g, Show h, Show i, Show j, Show k,
+ Show l, Show m, Show n, Show o)
+ => Show (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o) where
+ showsPrec _ (a,b,c,d,e,f,g,h,i,j,k,l,m,n,o) s
+ = show_tuple [shows a, shows b, shows c, shows d, shows e, shows f, shows g, shows h,
+ shows i, shows j, shows k, shows l, shows m, shows n, shows o] s
+
+show_tuple :: [ShowS] -> ShowS
+show_tuple ss = showChar '('
+ . foldr1 (\s r -> s . showChar ',' . r) ss
+ . showChar ')'
\end{code}
%*********************************************************
-%* *
+%* *
\subsection{Support code for @Show@}
-%* *
+%* *
%*********************************************************
\begin{code}
--
-- > showLitChar '\n' s = "\\n" ++ s
--
-showLitChar :: Char -> ShowS
+showLitChar :: Char -> ShowS
showLitChar c s | c > '\DEL' = showChar '\\' (protectEsc isDec (shows (ord c)) s)
-showLitChar '\DEL' s = showString "\\DEL" s
-showLitChar '\\' s = showString "\\\\" s
+showLitChar '\DEL' s = showString "\\DEL" s
+showLitChar '\\' s = showString "\\\\" s
showLitChar c s | c >= ' ' = showChar c s
-showLitChar '\a' s = showString "\\a" s
-showLitChar '\b' s = showString "\\b" s
-showLitChar '\f' s = showString "\\f" s
-showLitChar '\n' s = showString "\\n" s
-showLitChar '\r' s = showString "\\r" s
-showLitChar '\t' s = showString "\\t" s
-showLitChar '\v' s = showString "\\v" s
-showLitChar '\SO' s = protectEsc (== 'H') (showString "\\SO") s
-showLitChar c s = showString ('\\' : asciiTab!!ord c) s
- -- I've done manual eta-expansion here, becuase otherwise it's
- -- impossible to stop (asciiTab!!ord) getting floated out as an MFE
+showLitChar '\a' s = showString "\\a" s
+showLitChar '\b' s = showString "\\b" s
+showLitChar '\f' s = showString "\\f" s
+showLitChar '\n' s = showString "\\n" s
+showLitChar '\r' s = showString "\\r" s
+showLitChar '\t' s = showString "\\t" s
+showLitChar '\v' s = showString "\\v" s
+showLitChar '\SO' s = protectEsc (== 'H') (showString "\\SO") s
+showLitChar c s = showString ('\\' : asciiTab!!ord c) s
+ -- I've done manual eta-expansion here, becuase otherwise it's
+ -- impossible to stop (asciiTab!!ord) getting floated out as an MFE
+
+showLitString :: String -> ShowS
+-- | Same as 'showLitChar', but for strings
+-- It converts the string to a string using Haskell escape conventions
+-- for non-printable characters. Does not add double-quotes around the
+-- whole thing; the caller should do that.
+-- The main difference from showLitChar (apart from the fact that the
+-- argument is a string not a list) is that we must escape double-quotes
+showLitString [] s = s
+showLitString ('"' : cs) s = showString "\\\"" (showLitString cs s)
+showLitString (c : cs) s = showLitChar c (showLitString cs s)
+ -- Making 's' an explicit parameter makes it clear to GHC that
+ -- showLitString has arity 2, which avoids it allocating an extra lambda
+ -- The sticking point is the recursive call to (showLitString cs), which
+ -- it can't figure out would be ok with arity 2.
+
+showMultiLineString :: String -> [String]
+-- | Like 'showLitString' (expand escape characters using Haskell
+-- escape conventions), but
+-- * break the string into multiple lines
+-- * wrap the entire thing in double quotes
+-- Example: @breakMultiLineString "hello\ngoodbye\nblah"@
+-- returns @["\"hello\\", "\\goodbye\\", "\\blah\"" ]@
+-- where those "\\" are really just a single backslash
+-- (but I'm writing them here as Haskell literals)
+showMultiLineString str
+ = go '\"' str
+ where
+ go ch s = case break (== '\n') s of
+ (l, _:s'@(_:_)) -> (ch : showLitString l "\\") : go '\\' s'
+ (l, _) -> [ch : showLitString l "\""]
+isDec :: Char -> Bool
isDec c = c >= '0' && c <= '9'
protectEsc :: (Char -> Bool) -> ShowS -> ShowS
-protectEsc p f = f . cont
- where cont s@(c:_) | p c = "\\&" ++ s
- cont s = s
+protectEsc p f = f . cont
+ where cont s@(c:_) | p c = "\\&" ++ s
+ cont s = s
asciiTab :: [String]
asciiTab = -- Using an array drags in the array module. listArray ('\NUL', ' ')
- ["NUL", "SOH", "STX", "ETX", "EOT", "ENQ", "ACK", "BEL",
- "BS", "HT", "LF", "VT", "FF", "CR", "SO", "SI",
- "DLE", "DC1", "DC2", "DC3", "DC4", "NAK", "SYN", "ETB",
- "CAN", "EM", "SUB", "ESC", "FS", "GS", "RS", "US",
- "SP"]
+ ["NUL", "SOH", "STX", "ETX", "EOT", "ENQ", "ACK", "BEL",
+ "BS", "HT", "LF", "VT", "FF", "CR", "SO", "SI",
+ "DLE", "DC1", "DC2", "DC3", "DC4", "NAK", "SYN", "ETB",
+ "CAN", "EM", "SUB", "ESC", "FS", "GS", "RS", "US",
+ "SP"]
\end{code}
Code specific for Ints.
intToDigit (I# i)
| i >=# 0# && i <=# 9# = unsafeChr (ord '0' `plusInt` I# i)
| i >=# 10# && i <=# 15# = unsafeChr (ord 'a' `minusInt` ten `plusInt` I# i)
- | otherwise = error ("Char.intToDigit: not a digit " ++ show (I# i))
+ | otherwise = error ("Char.intToDigit: not a digit " ++ show (I# i))
+ten :: Int
ten = I# 10#
showSignedInt :: Int -> Int -> ShowS
itos :: Int# -> String -> String
itos n# cs
- | n# <# 0# = let
- n'# = negateInt# n#
- in if n'# <# 0# -- minInt?
- then '-' : itos' (negateInt# (n'# `quotInt#` 10#))
- (itos' (negateInt# (n'# `remInt#` 10#)) cs)
- else '-' : itos' n'# cs
+ | n# <# 0# =
+ let !(I# minInt#) = minInt in
+ if n# ==# minInt#
+ -- negateInt# minInt overflows, so we can't do that:
+ then '-' : itos' (negateInt# (n# `quotInt#` 10#))
+ (itos' (negateInt# (n# `remInt#` 10#)) cs)
+ else '-' : itos' (negateInt# n#) cs
| otherwise = itos' n# cs
where
itos' :: Int# -> String -> String
- itos' n# cs
- | n# <# 10# = C# (chr# (ord# '0'# +# n#)) : cs
- | otherwise = case chr# (ord# '0'# +# (n# `remInt#` 10#)) of { c# ->
- itos' (n# `quotInt#` 10#) (C# c# : cs) }
+ itos' x# cs'
+ | x# <# 10# = C# (chr# (ord# '0'# +# x#)) : cs'
+ | otherwise = case chr# (ord# '0'# +# (x# `remInt#` 10#)) of { c# ->
+ itos' (x# `quotInt#` 10#) (C# c# : cs') }
\end{code}
+
projects / ghc-base.git / blobdiff