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Use explicit language extensions & remove extension fields from base.cabal
[ghc-base.git]
/
Text
/
ParserCombinators
/
ReadPrec.hs
diff --git
a/Text/ParserCombinators/ReadPrec.hs
b/Text/ParserCombinators/ReadPrec.hs
index
77cd61e
..
f282d1a
100644
(file)
--- a/
Text/ParserCombinators/ReadPrec.hs
+++ b/
Text/ParserCombinators/ReadPrec.hs
@@
-1,4
+1,5
@@
-{-# OPTIONS -fno-implicit-prelude #-}
+{-# LANGUAGE CPP, NoImplicitPrelude #-}
+
-----------------------------------------------------------------------------
-- |
-- Module : Text.ParserCombinators.ReadPrec
-----------------------------------------------------------------------------
-- |
-- Module : Text.ParserCombinators.ReadPrec
@@
-7,7
+8,7
@@
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
--
-- Maintainer : libraries@haskell.org
-- Stability : provisional
--- Portability : portable
+-- Portability : non-portable (uses Text.ParserCombinators.ReadP)
--
-- This library defines parser combinators for precedence parsing.
--
-- This library defines parser combinators for precedence parsing.
@@
-28,10
+29,11
@@
module Text.ParserCombinators.ReadPrec
reset, -- :: ReadPrec a -> ReadPrec a
-- * Other operations
reset, -- :: ReadPrec a -> ReadPrec a
-- * Other operations
- -- All are based directly on their similarly-naned 'ReadP' counterparts.
+ -- | All are based directly on their similarly-named 'ReadP' counterparts.
get, -- :: ReadPrec Char
look, -- :: ReadPrec String
(+++), -- :: ReadPrec a -> ReadPrec a -> ReadPrec a
get, -- :: ReadPrec Char
look, -- :: ReadPrec String
(+++), -- :: ReadPrec a -> ReadPrec a -> ReadPrec a
+ (<++), -- :: ReadPrec a -> ReadPrec a -> ReadPrec a
pfail, -- :: ReadPrec a
choice, -- :: [ReadPrec a] -> ReadPrec a
pfail, -- :: ReadPrec a
choice, -- :: [ReadPrec a] -> ReadPrec a
@@
-46,6
+48,7
@@
module Text.ParserCombinators.ReadPrec
import Text.ParserCombinators.ReadP
( ReadP
import Text.ParserCombinators.ReadP
( ReadP
+ , ReadS
, readP_to_S
, readS_to_P
)
, readP_to_S
, readS_to_P
)
@@
-53,18
+56,20
@@
import Text.ParserCombinators.ReadP
import qualified Text.ParserCombinators.ReadP as ReadP
( get
, look
import qualified Text.ParserCombinators.ReadP as ReadP
( get
, look
- , (+++)
+ , (+++), (<++)
, pfail
)
import Control.Monad( MonadPlus(..) )
, pfail
)
import Control.Monad( MonadPlus(..) )
+#ifdef __GLASGOW_HASKELL__
import GHC.Num( Num(..) )
import GHC.Base
import GHC.Num( Num(..) )
import GHC.Base
+#endif
-- ---------------------------------------------------------------------------
-- The readPrec type
-- ---------------------------------------------------------------------------
-- The readPrec type
-newtype ReadPrec a = P { unP :: Prec -> ReadP a }
+newtype ReadPrec a = P (Prec -> ReadP a)
-- Functor, Monad, MonadPlus
-- Functor, Monad, MonadPlus
@@
-91,49
+96,60
@@
minPrec = 0
-- Operations over ReadPrec
lift :: ReadP a -> ReadPrec a
-- Operations over ReadPrec
lift :: ReadP a -> ReadPrec a
--- ^ Lift a predence-insensitive 'ReadP' to a 'ReadPrec'
+-- ^ Lift a precedence-insensitive 'ReadP' to a 'ReadPrec'.
lift m = P (\_ -> m)
step :: ReadPrec a -> ReadPrec a
lift m = P (\_ -> m)
step :: ReadPrec a -> ReadPrec a
--- ^ Increases the precedence context by one
+-- ^ Increases the precedence context by one.
step (P f) = P (\n -> f (n+1))
reset :: ReadPrec a -> ReadPrec a
step (P f) = P (\n -> f (n+1))
reset :: ReadPrec a -> ReadPrec a
--- ^ Resets the precedence context to zero
-reset (P f) = P (\n -> f minPrec)
+-- ^ Resets the precedence context to zero.
+reset (P f) = P (\_ -> f minPrec)
prec :: Prec -> ReadPrec a -> ReadPrec a
prec :: Prec -> ReadPrec a -> ReadPrec a
--- ^ @(prec n p)@ checks that the precedence context is
--- less than or equal to n,
+-- ^ @(prec n p)@ checks whether the precedence context is
+-- less than or equal to @n@, and
+--
-- * if not, fails
-- * if not, fails
--- * if so, parses p in context n
+--
+-- * if so, parses @p@ in context @n@.
prec n (P f) = P (\c -> if c <= n then f n else ReadP.pfail)
-- ---------------------------------------------------------------------------
-- Derived operations
get :: ReadPrec Char
prec n (P f) = P (\c -> if c <= n then f n else ReadP.pfail)
-- ---------------------------------------------------------------------------
-- Derived operations
get :: ReadPrec Char
+-- ^ Consumes and returns the next character.
+-- Fails if there is no input left.
get = lift ReadP.get
look :: ReadPrec String
get = lift ReadP.get
look :: ReadPrec String
+-- ^ Look-ahead: returns the part of the input that is left, without
+-- consuming it.
look = lift ReadP.look
(+++) :: ReadPrec a -> ReadPrec a -> ReadPrec a
look = lift ReadP.look
(+++) :: ReadPrec a -> ReadPrec a -> ReadPrec a
+-- ^ Symmetric choice.
P f1 +++ P f2 = P (\n -> f1 n ReadP.+++ f2 n)
P f1 +++ P f2 = P (\n -> f1 n ReadP.+++ f2 n)
+(<++) :: ReadPrec a -> ReadPrec a -> ReadPrec a
+-- ^ Local, exclusive, left-biased choice: If left parser
+-- locally produces any result at all, then right parser is
+-- not used.
+P f1 <++ P f2 = P (\n -> f1 n ReadP.<++ f2 n)
+
pfail :: ReadPrec a
pfail :: ReadPrec a
+-- ^ Always fails.
pfail = lift ReadP.pfail
choice :: [ReadPrec a] -> ReadPrec a
pfail = lift ReadP.pfail
choice :: [ReadPrec a] -> ReadPrec a
+-- ^ Combines all parsers in the specified list.
choice ps = foldr (+++) pfail ps
-- ---------------------------------------------------------------------------
-- Converting between ReadPrec and Read
choice ps = foldr (+++) pfail ps
-- ---------------------------------------------------------------------------
-- Converting between ReadPrec and Read
--- We define a local version of ReadS here,
--- because its "real" definition site is in GHC.Read
-type ReadS a = String -> [(a,String)]
-
readPrec_to_P :: ReadPrec a -> (Int -> ReadP a)
readPrec_to_P (P f) = f
readPrec_to_P :: ReadPrec a -> (Int -> ReadP a)
readPrec_to_P (P f) = f