% (c) The GRASP Project, Glasgow University, 1992-1998
%
-Outputable: defines classes for pretty-printing and forcing, both
-forms of ``output.''
-
\begin{code}
+-- | This module defines classes and functions for pretty-printing. It also
+-- exports a number of helpful debugging and other utilities such as 'trace' and 'panic'.
+--
+-- The interface to this module is very similar to the standard Hughes-PJ pretty printing
+-- module, except that it exports a number of additional functions that are rarely used,
+-- and works over the 'SDoc' type.
module Outputable (
- Outputable(..), OutputableBndr(..), -- Class
-
- BindingSite(..),
-
- PprStyle, CodeStyle(..), PrintUnqualified, alwaysQualify, neverQualify,
- QualifyName(..),
- getPprStyle, withPprStyle, withPprStyleDoc,
- pprDeeper, pprDeeperList, pprSetDepth,
- codeStyle, userStyle, debugStyle, dumpStyle, asmStyle,
- ifPprDebug, qualName, qualModule,
- mkErrStyle, defaultErrStyle, defaultDumpStyle, defaultUserStyle,
- mkUserStyle,
+ -- * Type classes
+ Outputable(..), OutputableBndr(..),
- SDoc, -- Abstract
+ -- * Pretty printing combinators
+ SDoc,
docToSDoc,
interppSP, interpp'SP, pprQuotedList, pprWithCommas,
empty, nest,
- text, char, ftext, ptext,
+ char,
+ text, ftext, ptext,
int, integer, float, double, rational,
parens, cparen, brackets, braces, quotes, doubleQuotes, angleBrackets,
semi, comma, colon, dcolon, space, equals, dot, arrow,
lparen, rparen, lbrack, rbrack, lbrace, rbrace, underscore,
(<>), (<+>), hcat, hsep,
- ($$), ($+$), vcat,
+ ($$), ($+$), vcat,
sep, cat,
fsep, fcat,
hang, punctuate,
speakNth, speakNTimes, speakN, speakNOf, plural,
+ -- * Converting 'SDoc' into strings and outputing it
printSDoc, printErrs, hPrintDump, printDump,
printForC, printForAsm, printForUser, printForUserPartWay,
pprCode, mkCodeStyle,
- showSDoc, showSDocForUser, showSDocDebug, showSDocDump,
+ showSDoc, showSDocForUser, showSDocDebug, showSDocDump, showPpr,
showSDocUnqual, showsPrecSDoc,
- pprHsChar, pprHsString,
- -- error handling
- pprPanic, assertPprPanic, pprPanic#, pprPgmError,
- pprTrace, warnPprTrace,
- trace, pgmError, panic, panic#, assertPanic
- ) where
+ pprInfixVar, pprPrefixVar,
+ pprHsChar, pprHsString, pprHsInfix, pprHsVar,
+ pprFastFilePath,
-#include "HsVersions.h"
+ -- * Controlling the style in which output is printed
+ BindingSite(..),
+ PprStyle, CodeStyle(..), PrintUnqualified, alwaysQualify, neverQualify,
+ QualifyName(..),
+ getPprStyle, withPprStyle, withPprStyleDoc,
+ pprDeeper, pprDeeperList, pprSetDepth,
+ codeStyle, userStyle, debugStyle, dumpStyle, asmStyle,
+ ifPprDebug, qualName, qualModule,
+ mkErrStyle, defaultErrStyle, defaultDumpStyle, defaultUserStyle,
+ mkUserStyle, Depth(..),
+
+ -- * Error handling and debugging utilities
+ pprPanic, assertPprPanic, pprPanicFastInt, pprPgmError,
+ pprTrace, warnPprTrace,
+ trace, pgmError, panic, panicFastInt, assertPanic
+ ) where
import {-# SOURCE #-} Module( Module, ModuleName, moduleName )
import {-# SOURCE #-} OccName( OccName )
-import StaticFlags ( opt_PprStyle_Debug, opt_PprUserLength )
-import FastString
+import StaticFlags
+import FastString
import FastTypes
-import GHC.Ptr
import qualified Pretty
import Pretty ( Doc, Mode(..) )
+import Char ( isAlpha )
import Panic
import Data.Word ( Word32 )
import System.IO ( Handle, stderr, stdout, hFlush )
import Data.Char ( ord )
+import System.FilePath
\end{code}
neverQualifyModules :: QueryQualifyModule
neverQualifyModules _ = False
-type QueryQualifies = (QueryQualifyName, QueryQualifyModule)
-
-alwaysQualify, neverQualify :: QueryQualifies
+alwaysQualify, neverQualify :: PrintUnqualified
alwaysQualify = (alwaysQualifyNames, alwaysQualifyModules)
neverQualify = (neverQualifyNames, neverQualifyModules)
| opt_PprStyle_Debug = mkUserStyle alwaysQualify AllTheWay
| otherwise = mkUserStyle alwaysQualify (PartWay opt_PprUserLength)
-mkUserStyle :: QueryQualifies -> Depth -> PprStyle
+mkUserStyle :: PrintUnqualified -> Depth -> PprStyle
mkUserStyle unqual depth
| opt_PprStyle_Debug = PprDebug
| otherwise = PprUser unqual depth
showSDocForUser unqual doc = show (doc (mkUserStyle unqual AllTheWay))
showSDocUnqual :: SDoc -> String
--- Only used in the gruesome HsExpr.isOperator
+-- Only used in the gruesome isOperator
showSDocUnqual d = show (d (mkUserStyle neverQualify AllTheWay))
showsPrecSDoc :: Int -> SDoc -> ShowS
showSDocDebug :: SDoc -> String
showSDocDebug d = show (d PprDebug)
+
+showPpr :: Outputable a => a -> String
+showPpr = showSDoc . ppr
\end{code}
\begin{code}
docToSDoc d = \_ -> d
empty :: SDoc
-text :: String -> SDoc
char :: Char -> SDoc
+text :: String -> SDoc
ftext :: FastString -> SDoc
-ptext :: Ptr t -> SDoc
+ptext :: LitString -> SDoc
int :: Int -> SDoc
integer :: Integer -> SDoc
float :: Float -> SDoc
rational :: Rational -> SDoc
empty _sty = Pretty.empty
-text s _sty = Pretty.text s
char c _sty = Pretty.char c
+text s _sty = Pretty.text s
ftext s _sty = Pretty.ftext s
ptext s _sty = Pretty.ptext s
int n _sty = Pretty.int n
colon _sty = Pretty.colon
equals _sty = Pretty.equals
space _sty = Pretty.space
-dcolon _sty = Pretty.ptext SLIT("::")
-arrow _sty = Pretty.ptext SLIT("->")
+dcolon _sty = Pretty.ptext (sLit "::")
+arrow _sty = Pretty.ptext (sLit "->")
underscore = char '_'
dot = char '.'
lparen _sty = Pretty.lparen
rbrace _sty = Pretty.rbrace
nest :: Int -> SDoc -> SDoc
-(<>), (<+>), ($$), ($+$) :: SDoc -> SDoc -> SDoc
+-- ^ Indent 'SDoc' some specified amount
+(<>) :: SDoc -> SDoc -> SDoc
+-- ^ Join two 'SDoc' together horizontally without a gap
+(<+>) :: SDoc -> SDoc -> SDoc
+-- ^ Join two 'SDoc' together horizontally with a gap between them
+($$) :: SDoc -> SDoc -> SDoc
+-- ^ Join two 'SDoc' together vertically; if there is
+-- no vertical overlap it "dovetails" the two onto one line
+($+$) :: SDoc -> SDoc -> SDoc
+-- ^ Join two 'SDoc' together vertically
nest n d sty = Pretty.nest n (d sty)
(<>) d1 d2 sty = (Pretty.<>) (d1 sty) (d2 sty)
($$) d1 d2 sty = (Pretty.$$) (d1 sty) (d2 sty)
($+$) d1 d2 sty = (Pretty.$+$) (d1 sty) (d2 sty)
-hcat, hsep, vcat, sep, cat, fsep, fcat :: [SDoc] -> SDoc
+hcat :: [SDoc] -> SDoc
+-- ^ Concatenate 'SDoc' horizontally
+hsep :: [SDoc] -> SDoc
+-- ^ Concatenate 'SDoc' horizontally with a space between each one
+vcat :: [SDoc] -> SDoc
+-- ^ Concatenate 'SDoc' vertically with dovetailing
+sep :: [SDoc] -> SDoc
+-- ^ Separate: is either like 'hsep' or like 'vcat', depending on what fits
+cat :: [SDoc] -> SDoc
+-- ^ Catenate: is either like 'hcat' or like 'vcat', depending on what fits
+fsep :: [SDoc] -> SDoc
+-- ^ A paragraph-fill combinator. It's much like sep, only it
+-- keeps fitting things on one line until it can't fit any more.
+fcat :: [SDoc] -> SDoc
+-- ^ This behaves like 'fsep', but it uses '<>' for horizontal conposition rather than '<+>'
hcat ds sty = Pretty.hcat [d sty | d <- ds]
fsep ds sty = Pretty.fsep [d sty | d <- ds]
fcat ds sty = Pretty.fcat [d sty | d <- ds]
-hang :: SDoc -> Int -> SDoc -> SDoc
-
+hang :: SDoc -- ^ The header
+ -> Int -- ^ Amount to indent the hung body
+ -> SDoc -- ^ The hung body, indented and placed below the header
+ -> SDoc
hang d1 n d2 sty = Pretty.hang (d1 sty) n (d2 sty)
-punctuate :: SDoc -> [SDoc] -> [SDoc]
+punctuate :: SDoc -- ^ The punctuation
+ -> [SDoc] -- ^ The list that will have punctuation added between every adjacent pair of elements
+ -> [SDoc] -- ^ Punctuated list
punctuate _ [] = []
punctuate p (d:ds) = go d ds
where
%************************************************************************
\begin{code}
+-- | Class designating that some type has an 'SDoc' representation
class Outputable a where
ppr :: a -> SDoc
\end{code}
\begin{code}
instance Outputable Bool where
- ppr True = ptext SLIT("True")
- ppr False = ptext SLIT("False")
+ ppr True = ptext (sLit "True")
+ ppr False = ptext (sLit "False")
instance Outputable Int where
ppr n = int n
+instance Outputable Word32 where
+ ppr n = integer $ fromIntegral n
+
instance Outputable () where
ppr _ = text "()"
ppr (x,y) = parens (sep [ppr x <> comma, ppr y])
instance Outputable a => Outputable (Maybe a) where
- ppr Nothing = ptext SLIT("Nothing")
- ppr (Just x) = ptext SLIT("Just") <+> ppr x
+ ppr Nothing = ptext (sLit "Nothing")
+ ppr (Just x) = ptext (sLit "Just") <+> ppr x
instance (Outputable a, Outputable b) => Outputable (Either a b) where
- ppr (Left x) = ptext SLIT("Left") <+> ppr x
- ppr (Right y) = ptext SLIT("Right") <+> ppr y
+ ppr (Left x) = ptext (sLit "Left") <+> ppr x
+ ppr (Right y) = ptext (sLit "Right") <+> ppr y
-- ToDo: may not be used
instance (Outputable a, Outputable b, Outputable c) => Outputable (a, b, c) where
-- no double quotes or anything
\end{code}
-
%************************************************************************
%* *
\subsection{The @OutputableBndr@ class}
%* *
%************************************************************************
-When we print a binder, we often want to print its type too.
-The @OutputableBndr@ class encapsulates this idea.
-
-@BindingSite@ is used to tell the thing that prints binder what
-language construct is binding the identifier. This can be used
-to decide how much info to print.
-
\begin{code}
+-- | 'BindingSite' is used to tell the thing that prints binder what
+-- language construct is binding the identifier. This can be used
+-- to decide how much info to print.
data BindingSite = LambdaBind | CaseBind | LetBind
+-- | When we print a binder, we often want to print its type too.
+-- The @OutputableBndr@ class encapsulates this idea.
class Outputable a => OutputableBndr a where
pprBndr :: BindingSite -> a -> SDoc
pprBndr _b x = ppr x
\end{code}
-
-
%************************************************************************
%* *
\subsection{Random printing helpers}
%************************************************************************
\begin{code}
--- We have 31-bit Chars and will simply use Show instances
--- of Char and String.
+-- We have 31-bit Chars and will simply use Show instances of Char and String.
+-- | Special combinator for showing character literals.
pprHsChar :: Char -> SDoc
pprHsChar c | c > '\x10ffff' = char '\\' <> text (show (fromIntegral (ord c) :: Word32))
| otherwise = text (show c)
+-- | Special combinator for showing string literals.
pprHsString :: FastString -> SDoc
pprHsString fs = text (show (unpackFS fs))
-\end{code}
+---------------------
+-- Put a name in parens if it's an operator
+pprPrefixVar :: Bool -> SDoc -> SDoc
+pprPrefixVar is_operator pp_v
+ | is_operator = parens pp_v
+ | otherwise = pp_v
+
+-- Put a name in backquotes if it's not an operator
+pprInfixVar :: Bool -> SDoc -> SDoc
+pprInfixVar is_operator pp_v
+ | is_operator = pp_v
+ | otherwise = char '`' <> pp_v <> char '`'
+
+---------------------
+-- pprHsVar and pprHsInfix use the gruesome isOperator, which
+-- in turn uses (showSDoc (ppr v)), rather than isSymOcc (getOccName v).
+-- Reason: it means that pprHsVar doesn't need a NamedThing context,
+-- which none of the HsSyn printing functions do
+pprHsVar, pprHsInfix :: Outputable name => name -> SDoc
+pprHsVar v = pprPrefixVar (isOperator pp_v) pp_v
+ where pp_v = ppr v
+pprHsInfix v = pprInfixVar (isOperator pp_v) pp_v
+ where pp_v = ppr v
+
+isOperator :: SDoc -> Bool
+isOperator ppr_v
+ = case showSDocUnqual ppr_v of
+ ('(':_) -> False -- (), (,) etc
+ ('[':_) -> False -- []
+ ('$':c:_) -> not (isAlpha c) -- Don't treat $d as an operator
+ (':':c:_) -> not (isAlpha c) -- Don't treat :T as an operator
+ ('_':_) -> False -- Not an operator
+ (c:_) -> not (isAlpha c) -- Starts with non-alpha
+ _ -> False
+
+pprFastFilePath :: FastString -> SDoc
+pprFastFilePath path = text $ normalise $ unpackFS path
+\end{code}
%************************************************************************
%* *
%************************************************************************
\begin{code}
-pprWithCommas :: (a -> SDoc) -> [a] -> SDoc
+pprWithCommas :: (a -> SDoc) -- ^ The pretty printing function to use
+ -> [a] -- ^ The things to be pretty printed
+ -> SDoc -- ^ 'SDoc' where the things have been pretty printed,
+ -- comma-separated and finally packed into a paragraph.
pprWithCommas pp xs = fsep (punctuate comma (map pp xs))
+-- | Returns the seperated concatenation of the pretty printed things.
interppSP :: Outputable a => [a] -> SDoc
interppSP xs = sep (map ppr xs)
+-- | Returns the comma-seperated concatenation of the pretty printed things.
interpp'SP :: Outputable a => [a] -> SDoc
interpp'SP xs = sep (punctuate comma (map ppr xs))
+-- | Returns the comma-seperated concatenation of the quoted pretty printed things.
+--
+-- > [x,y,z] ==> `x', `y', `z'
pprQuotedList :: Outputable a => [a] -> SDoc
--- [x,y,z] ==> `x', `y', `z'
pprQuotedList xs = hsep (punctuate comma (map (quotes . ppr) xs))
\end{code}
%* *
%************************************************************************
-@speakNth@ converts an integer to a verbal index; eg 1 maps to
-``first'' etc.
-
\begin{code}
+-- | Converts an integer to a verbal index:
+--
+-- > speakNth 1 = text "first"
+-- > speakNth 5 = text "fifth"
+-- > speakNth 21 = text "21st"
speakNth :: Int -> SDoc
-speakNth 1 = ptext SLIT("first")
-speakNth 2 = ptext SLIT("second")
-speakNth 3 = ptext SLIT("third")
-speakNth 4 = ptext SLIT("fourth")
-speakNth 5 = ptext SLIT("fifth")
-speakNth 6 = ptext SLIT("sixth")
+speakNth 1 = ptext (sLit "first")
+speakNth 2 = ptext (sLit "second")
+speakNth 3 = ptext (sLit "third")
+speakNth 4 = ptext (sLit "fourth")
+speakNth 5 = ptext (sLit "fifth")
+speakNth 6 = ptext (sLit "sixth")
speakNth n = hcat [ int n, text suffix ]
where
suffix | n <= 20 = "th" -- 11,12,13 are non-std
last_dig = n `rem` 10
+-- | Converts an integer to a verbal multiplicity:
+--
+-- > speakN 0 = text "none"
+-- > speakN 5 = text "five"
+-- > speakN 10 = text "10"
speakN :: Int -> SDoc
-speakN 0 = ptext SLIT("none") -- E.g. "he has none"
-speakN 1 = ptext SLIT("one") -- E.g. "he has one"
-speakN 2 = ptext SLIT("two")
-speakN 3 = ptext SLIT("three")
-speakN 4 = ptext SLIT("four")
-speakN 5 = ptext SLIT("five")
-speakN 6 = ptext SLIT("six")
+speakN 0 = ptext (sLit "none") -- E.g. "he has none"
+speakN 1 = ptext (sLit "one") -- E.g. "he has one"
+speakN 2 = ptext (sLit "two")
+speakN 3 = ptext (sLit "three")
+speakN 4 = ptext (sLit "four")
+speakN 5 = ptext (sLit "five")
+speakN 6 = ptext (sLit "six")
speakN n = int n
+-- | Converts an integer and object description to a statement about the
+-- multiplicity of those objects:
+--
+-- > speakNOf 0 (text "melon") = text "no melons"
+-- > speakNOf 1 (text "melon") = text "one melon"
+-- > speakNOf 3 (text "melon") = text "three melons"
speakNOf :: Int -> SDoc -> SDoc
-speakNOf 0 d = ptext SLIT("no") <+> d <> char 's' -- E.g. "no arguments"
-speakNOf 1 d = ptext SLIT("one") <+> d -- E.g. "one argument"
+speakNOf 0 d = ptext (sLit "no") <+> d <> char 's'
+speakNOf 1 d = ptext (sLit "one") <+> d -- E.g. "one argument"
speakNOf n d = speakN n <+> d <> char 's' -- E.g. "three arguments"
+-- | Converts a strictly positive integer into a number of times:
+--
+-- > speakNTimes 1 = text "once"
+-- > speakNTimes 2 = text "twice"
+-- > speakNTimes 4 = text "4 times"
speakNTimes :: Int {- >=1 -} -> SDoc
-speakNTimes t | t == 1 = ptext SLIT("once")
- | t == 2 = ptext SLIT("twice")
- | otherwise = speakN t <+> ptext SLIT("times")
-
+speakNTimes t | t == 1 = ptext (sLit "once")
+ | t == 2 = ptext (sLit "twice")
+ | otherwise = speakN t <+> ptext (sLit "times")
+
+-- | Determines the pluralisation suffix appropriate for the length of a list:
+--
+-- > plural [] = char 's'
+-- > plural ["Hello"] = empty
+-- > plural ["Hello", "World"] = char 's'
plural :: [a] -> SDoc
plural [_] = empty -- a bit frightening, but there you are
plural _ = char 's'
%************************************************************************
\begin{code}
-pprPanic, pprPgmError :: String -> SDoc -> a
+pprPanic :: String -> SDoc -> a
+-- ^ Throw an exception saying "bug in GHC"
+pprPgmError :: String -> SDoc -> a
+-- ^ Throw an exception saying "bug in pgm being compiled" (used for unusual program errors)
pprTrace :: String -> SDoc -> a -> a
-pprPanic = pprAndThen panic -- Throw an exn saying "bug in GHC"
+-- ^ If debug output is on, show some 'SDoc' on the screen
+
+pprPanic = pprAndThen panic
+
+pprPgmError = pprAndThen pgmError
-pprPgmError = pprAndThen pgmError -- Throw an exn saying "bug in pgm being compiled"
- -- (used for unusual pgm errors)
-pprTrace = pprAndThen trace
+pprTrace str doc x
+ | opt_NoDebugOutput = x
+ | otherwise = pprAndThen trace str doc x
-pprPanic# :: String -> SDoc -> FastInt
-pprPanic# heading pretty_msg = panic# (show (doc PprDebug))
+pprPanicFastInt :: String -> SDoc -> FastInt
+-- ^ Specialization of pprPanic that can be safely used with 'FastInt'
+pprPanicFastInt heading pretty_msg = panicFastInt (show (doc PprDebug))
where
doc = text heading <+> pretty_msg
doc = sep [text heading, nest 4 pretty_msg]
assertPprPanic :: String -> Int -> SDoc -> a
+-- ^ Panic with an assertation failure, recording the given file and line number.
+-- Should typically be accessed with the ASSERT family of macros
assertPprPanic file line msg
= panic (show (doc PprDebug))
where
msg]
warnPprTrace :: Bool -> String -> Int -> SDoc -> a -> a
+-- ^ Just warn about an assertion failure, recording the given file and line number.
+-- Should typically be accessed with the WARN macros
+warnPprTrace _ _file _line _msg x | opt_NoDebugOutput = x
warnPprTrace False _file _line _msg x = x
warnPprTrace True file line msg x
= trace (show (doc PprDebug)) x