{-# LANGUAGE Trustworthy #-}{-# LANGUAGE NoImplicitPrelude #-}{-# LANGUAGE RankNTypes #-}{-# LANGUAGE MagicHash #-}{-# LANGUAGE DeriveFunctor #-}------------------------------------------------------------------------------- |-- Module : Text.ParserCombinators.ReadP-- Copyright : (c) The University of Glasgow 2002-- License : BSD-style (see the file libraries/base/LICENSE)---- Maintainer : libraries@haskell.org-- Stability : provisional-- Portability : non-portable (local universal quantification)---- This is a library of parser combinators, originally written by Koen Claessen.-- It parses all alternatives in parallel, so it never keeps hold of-- the beginning of the input string, a common source of space leaks with-- other parsers. The @('+++')@ choice combinator is genuinely commutative;-- it makes no difference which branch is \"shorter\".-----------------------------------------------------------------------------moduleText.ParserCombinators.ReadP(-- * The 'ReadP' typeReadP ,-- * Primitive operationsget ,look ,(+++) ,(<++) ,gather ,-- * Other operationspfail ,eof ,satisfy ,char ,string ,munch ,munch1 ,skipSpaces ,choice ,count ,between ,option ,optional ,many ,many1 ,skipMany ,skipMany1 ,sepBy ,sepBy1 ,endBy ,endBy1 ,chainr ,chainl ,chainl1 ,chainr1 ,manyTill ,-- * Running a parserReadS ,readP_to_S ,readS_to_P ,-- * Properties-- $properties)whereimportGHC.Unicode (isSpace )importGHC.List (replicate ,null )importGHC.Base hiding(many )importControl.Monad.Fail infixr5+++ ,<++ -------------------------------------------------------------------------- ReadS-- | A parser for a type @a@, represented as a function that takes a-- 'String' and returns a list of possible parses as @(a,'String')@ pairs.---- Note that this kind of backtracking parser is very inefficient;-- reading a large structure may be quite slow (cf 'ReadP').typeReadS a =String ->[(a ,String )]-- ----------------------------------------------------------------------------- The P type-- is representation type -- should be kept abstractdataP a =Get (Char->P a )|Look (String ->P a )|Fail |Result a (P a )|Final [(a ,String )]-- invariant: list is non-empty!derivingFunctor -- ^ @since 4.8.0.0-- Monad, MonadPlus-- | @since 4.5.0.0instanceApplicative P wherepure :: a -> P a
pure x :: a
x =a -> P a -> P a
forall a. a -> P a -> P a
Result a
x P a
forall a. P a
Fail <*> :: P (a -> b) -> P a -> P b
(<*>) =P (a -> b) -> P a -> P b
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
ap -- | @since 2.01instanceMonadPlus P -- | @since 2.01instanceMonad P where(Get f :: Char -> P a
f )>>= :: P a -> (a -> P b) -> P b
>>= k :: a -> P b
k =(Char -> P b) -> P b
forall a. (Char -> P a) -> P a
Get (\c :: Char
c ->Char -> P a
f Char
c P a -> (a -> P b) -> P b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= a -> P b
k )(Look f :: String -> P a
f )>>= k :: a -> P b
k =(String -> P b) -> P b
forall a. (String -> P a) -> P a
Look (\s :: String
s ->String -> P a
f String
s P a -> (a -> P b) -> P b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= a -> P b
k )Fail >>= _=P b
forall a. P a
Fail (Result x :: a
x p :: P a
p )>>= k :: a -> P b
k =a -> P b
k a
x P b -> P b -> P b
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> (P a
p P a -> (a -> P b) -> P b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= a -> P b
k )(Final r :: [(a, String)]
r )>>= k :: a -> P b
k =[(b, String)] -> P b
forall a. [(a, String)] -> P a
final [(b, String)
ys' |(x :: a
x ,s :: String
s )<-[(a, String)]
r ,(b, String)
ys' <-P b -> ReadS b
forall a. P a -> ReadS a
run (a -> P b
k a
x )String
s ]-- | @since 4.9.0.0instanceMonadFail P wherefail :: String -> P a
fail _=P a
forall a. P a
Fail -- | @since 4.5.0.0instanceAlternative P whereempty :: P a
empty =P a
forall a. P a
Fail -- most common case: two gets are combinedGet f1 :: Char -> P a
f1 <|> :: P a -> P a -> P a
<|> Get f2 :: Char -> P a
f2 =(Char -> P a) -> P a
forall a. (Char -> P a) -> P a
Get (\c :: Char
c ->Char -> P a
f1 Char
c P a -> P a -> P a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> Char -> P a
f2 Char
c )-- results are delivered as soon as possibleResult x :: a
x p :: P a
p <|> q :: P a
q =a -> P a -> P a
forall a. a -> P a -> P a
Result a
x (P a
p P a -> P a -> P a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> P a
q )p :: P a
p <|> Result x :: a
x q :: P a
q =a -> P a -> P a
forall a. a -> P a -> P a
Result a
x (P a
p P a -> P a -> P a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> P a
q )-- fail disappearsFail <|> p :: P a
p =P a
p p :: P a
p <|> Fail =P a
p -- two finals are combined-- final + look becomes one look and one final (=optimization)-- final + sthg else becomes one look and one finalFinal r :: [(a, String)]
r <|> Final t :: [(a, String)]
t =[(a, String)] -> P a
forall a. [(a, String)] -> P a
Final ([(a, String)]
r [(a, String)] -> [(a, String)] -> [(a, String)]
forall a. [a] -> [a] -> [a]
++ [(a, String)]
t )Final r :: [(a, String)]
r <|> Look f :: String -> P a
f =(String -> P a) -> P a
forall a. (String -> P a) -> P a
Look (\s :: String
s ->[(a, String)] -> P a
forall a. [(a, String)] -> P a
Final ([(a, String)]
r [(a, String)] -> [(a, String)] -> [(a, String)]
forall a. [a] -> [a] -> [a]
++ P a -> ReadS a
forall a. P a -> ReadS a
run (String -> P a
f String
s )String
s ))Final r :: [(a, String)]
r <|> p :: P a
p =(String -> P a) -> P a
forall a. (String -> P a) -> P a
Look (\s :: String
s ->[(a, String)] -> P a
forall a. [(a, String)] -> P a
Final ([(a, String)]
r [(a, String)] -> [(a, String)] -> [(a, String)]
forall a. [a] -> [a] -> [a]
++ P a -> ReadS a
forall a. P a -> ReadS a
run P a
p String
s ))Look f :: String -> P a
f <|> Final r :: [(a, String)]
r =(String -> P a) -> P a
forall a. (String -> P a) -> P a
Look (\s :: String
s ->[(a, String)] -> P a
forall a. [(a, String)] -> P a
Final (P a -> ReadS a
forall a. P a -> ReadS a
run (String -> P a
f String
s )String
s [(a, String)] -> [(a, String)] -> [(a, String)]
forall a. [a] -> [a] -> [a]
++ [(a, String)]
r ))p :: P a
p <|> Final r :: [(a, String)]
r =(String -> P a) -> P a
forall a. (String -> P a) -> P a
Look (\s :: String
s ->[(a, String)] -> P a
forall a. [(a, String)] -> P a
Final (P a -> ReadS a
forall a. P a -> ReadS a
run P a
p String
s [(a, String)] -> [(a, String)] -> [(a, String)]
forall a. [a] -> [a] -> [a]
++ [(a, String)]
r ))-- two looks are combined (=optimization)-- look + sthg else floats upwardsLook f :: String -> P a
f <|> Look g :: String -> P a
g =(String -> P a) -> P a
forall a. (String -> P a) -> P a
Look (\s :: String
s ->String -> P a
f String
s P a -> P a -> P a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> String -> P a
g String
s )Look f :: String -> P a
f <|> p :: P a
p =(String -> P a) -> P a
forall a. (String -> P a) -> P a
Look (\s :: String
s ->String -> P a
f String
s P a -> P a -> P a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> P a
p )p :: P a
p <|> Look f :: String -> P a
f =(String -> P a) -> P a
forall a. (String -> P a) -> P a
Look (\s :: String
s ->P a
p P a -> P a -> P a
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> String -> P a
f String
s )-- ----------------------------------------------------------------------------- The ReadP typenewtypeReadP a =R (forallb .(a ->P b )->P b )-- | @since 2.01instanceFunctor ReadP wherefmap :: (a -> b) -> ReadP a -> ReadP b
fmap h :: a -> b
h (R f :: forall b. (a -> P b) -> P b
f )=(forall b. (b -> P b) -> P b) -> ReadP b
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (\k :: b -> P b
k ->(a -> P b) -> P b
forall b. (a -> P b) -> P b
f (b -> P b
k (b -> P b) -> (a -> b) -> a -> P b
forall b c a. (b -> c) -> (a -> b) -> a -> c
. a -> b
h ))-- | @since 4.6.0.0instanceApplicative ReadP wherepure :: a -> ReadP a
pure x :: a
x =(forall b. (a -> P b) -> P b) -> ReadP a
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (\k :: a -> P b
k ->a -> P b
k a
x )<*> :: ReadP (a -> b) -> ReadP a -> ReadP b
(<*>) =ReadP (a -> b) -> ReadP a -> ReadP b
forall (m :: * -> *) a b. Monad m => m (a -> b) -> m a -> m b
ap -- liftA2 = liftM2-- | @since 2.01instanceMonad ReadP whereR m :: forall b. (a -> P b) -> P b
m >>= :: ReadP a -> (a -> ReadP b) -> ReadP b
>>= f :: a -> ReadP b
f =(forall b. (b -> P b) -> P b) -> ReadP b
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (\k :: b -> P b
k ->(a -> P b) -> P b
forall b. (a -> P b) -> P b
m (\a :: a
a ->letR m' :: forall b. (b -> P b) -> P b
m' =a -> ReadP b
f a
a in(b -> P b) -> P b
forall b. (b -> P b) -> P b
m' b -> P b
k ))-- | @since 4.9.0.0instanceMonadFail ReadP wherefail :: String -> ReadP a
fail _=(forall b. (a -> P b) -> P b) -> ReadP a
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (\_->P b
forall a. P a
Fail )-- | @since 4.6.0.0instanceAlternative ReadP whereempty :: ReadP a
empty =ReadP a
forall a. ReadP a
pfail <|> :: ReadP a -> ReadP a -> ReadP a
(<|>) =ReadP a -> ReadP a -> ReadP a
forall a. ReadP a -> ReadP a -> ReadP a
(+++) -- | @since 2.01instanceMonadPlus ReadP -- ----------------------------------------------------------------------------- Operations over Pfinal ::[(a ,String )]->P a -- Maintains invariant for Final constructorfinal :: [(a, String)] -> P a
final []=P a
forall a. P a
Fail final r :: [(a, String)]
r =[(a, String)] -> P a
forall a. [(a, String)] -> P a
Final [(a, String)]
r run ::P a ->ReadS a run :: P a -> ReadS a
run (Get f :: Char -> P a
f )(c :: Char
c :s :: String
s )=P a -> ReadS a
forall a. P a -> ReadS a
run (Char -> P a
f Char
c )String
s run (Look f :: String -> P a
f )s :: String
s =P a -> ReadS a
forall a. P a -> ReadS a
run (String -> P a
f String
s )String
s run (Result x :: a
x p :: P a
p )s :: String
s =(a
x ,String
s )(a, String) -> [(a, String)] -> [(a, String)]
forall a. a -> [a] -> [a]
:P a -> ReadS a
forall a. P a -> ReadS a
run P a
p String
s run (Final r :: [(a, String)]
r )_=[(a, String)]
r run __=[]-- ----------------------------------------------------------------------------- Operations over ReadPget ::ReadP Char-- ^ Consumes and returns the next character.-- Fails if there is no input left.get :: ReadP Char
get =(forall a. (Char -> P a) -> P a) -> ReadP Char
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R forall a. (Char -> P a) -> P a
Get look ::ReadP String -- ^ Look-ahead: returns the part of the input that is left, without-- consuming it.look :: ReadP String
look =(forall a. (String -> P a) -> P a) -> ReadP String
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R forall a. (String -> P a) -> P a
Look pfail ::ReadP a -- ^ Always fails.pfail :: ReadP a
pfail =(forall b. (a -> P b) -> P b) -> ReadP a
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (\_->P b
forall a. P a
Fail )(+++) ::ReadP a ->ReadP a ->ReadP a -- ^ Symmetric choice.R f1 :: forall b. (a -> P b) -> P b
f1 +++ :: ReadP a -> ReadP a -> ReadP a
+++ R f2 :: forall b. (a -> P b) -> P b
f2 =(forall b. (a -> P b) -> P b) -> ReadP a
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (\k :: a -> P b
k ->(a -> P b) -> P b
forall b. (a -> P b) -> P b
f1 a -> P b
k P b -> P b -> P b
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> (a -> P b) -> P b
forall b. (a -> P b) -> P b
f2 a -> P b
k )(<++) ::ReadP a ->ReadP a ->ReadP a -- ^ Local, exclusive, left-biased choice: If left parser-- locally produces any result at all, then right parser is-- not used.R f0 :: forall b. (a -> P b) -> P b
f0 <++ :: ReadP a -> ReadP a -> ReadP a
<++ q :: ReadP a
q =doString
s <-ReadP String
look P a -> String -> Int# -> ReadP a
probe ((a -> P a) -> P a
forall b. (a -> P b) -> P b
f0 a -> P a
forall (m :: * -> *) a. Monad m => a -> m a
return )String
s 0#whereprobe :: P a -> String -> Int# -> ReadP a
probe (Get f :: Char -> P a
f )(c :: Char
c :s :: String
s )n :: Int#
n =P a -> String -> Int# -> ReadP a
probe (Char -> P a
f Char
c )String
s (Int#
n Int# -> Int# -> Int#
+#1#)probe (Look f :: String -> P a
f )s :: String
s n :: Int#
n =P a -> String -> Int# -> ReadP a
probe (String -> P a
f String
s )String
s Int#
n probe p :: P a
p @(Result __)_n :: Int#
n =Int# -> ReadP ()
discard Int#
n ReadP () -> ReadP a -> ReadP a
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> (forall b. (a -> P b) -> P b) -> ReadP a
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (P a
p P a -> (a -> P b) -> P b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= )probe (Final r :: [(a, String)]
r )__=(forall b. (a -> P b) -> P b) -> ReadP a
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R ([(a, String)] -> P a
forall a. [(a, String)] -> P a
Final [(a, String)]
r P a -> (a -> P b) -> P b
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= )probe ___=ReadP a
q discard :: Int# -> ReadP ()
discard 0#=() -> ReadP ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()discard n :: Int#
n =ReadP Char
get ReadP Char -> ReadP () -> ReadP ()
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> Int# -> ReadP ()
discard (Int#
n Int# -> Int# -> Int#
-#1#)gather ::ReadP a ->ReadP (String ,a )-- ^ Transforms a parser into one that does the same, but-- in addition returns the exact characters read.-- IMPORTANT NOTE: 'gather' gives a runtime error if its first argument-- is built using any occurrences of readS_to_P.gather :: ReadP a -> ReadP (String, a)
gather (R m :: forall b. (a -> P b) -> P b
m )=(forall b. ((String, a) -> P b) -> P b) -> ReadP (String, a)
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (\k :: (String, a) -> P b
k ->(String -> String) -> P (String -> P b) -> P b
forall b. (String -> String) -> P (String -> P b) -> P b
gath String -> String
forall a. a -> a
id ((a -> P (String -> P b)) -> P (String -> P b)
forall b. (a -> P b) -> P b
m (\a :: a
a ->(String -> P b) -> P (String -> P b)
forall (m :: * -> *) a. Monad m => a -> m a
return (\s :: String
s ->(String, a) -> P b
k (String
s ,a
a )))))wheregath ::(String ->String )->P (String ->P b )->P b gath :: (String -> String) -> P (String -> P b) -> P b
gath l :: String -> String
l (Get f :: Char -> P (String -> P b)
f )=(Char -> P b) -> P b
forall a. (Char -> P a) -> P a
Get (\c :: Char
c ->(String -> String) -> P (String -> P b) -> P b
forall b. (String -> String) -> P (String -> P b) -> P b
gath (String -> String
l (String -> String) -> (String -> String) -> String -> String
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Char
c Char -> String -> String
forall a. a -> [a] -> [a]
:))(Char -> P (String -> P b)
f Char
c ))gath _Fail =P b
forall a. P a
Fail gath l :: String -> String
l (Look f :: String -> P (String -> P b)
f )=(String -> P b) -> P b
forall a. (String -> P a) -> P a
Look (\s :: String
s ->(String -> String) -> P (String -> P b) -> P b
forall b. (String -> String) -> P (String -> P b) -> P b
gath String -> String
l (String -> P (String -> P b)
f String
s ))gath l :: String -> String
l (Result k :: String -> P b
k p :: P (String -> P b)
p )=String -> P b
k (String -> String
l [])P b -> P b -> P b
forall (f :: * -> *) a. Alternative f => f a -> f a -> f a
<|> (String -> String) -> P (String -> P b) -> P b
forall b. (String -> String) -> P (String -> P b) -> P b
gath String -> String
l P (String -> P b)
p gath _(Final _)=String -> P b
forall a. String -> a
errorWithoutStackTrace "do not use readS_to_P in gather!"-- ----------------------------------------------------------------------------- Derived operationssatisfy ::(Char->Bool)->ReadP Char-- ^ Consumes and returns the next character, if it satisfies the-- specified predicate.satisfy :: (Char -> Bool) -> ReadP Char
satisfy p :: Char -> Bool
p =doChar
c <-ReadP Char
get ;ifChar -> Bool
p Char
c thenChar -> ReadP Char
forall (m :: * -> *) a. Monad m => a -> m a
return Char
c elseReadP Char
forall a. ReadP a
pfail char ::Char->ReadP Char-- ^ Parses and returns the specified character.char :: Char -> ReadP Char
char c :: Char
c =(Char -> Bool) -> ReadP Char
satisfy (Char
c Char -> Char -> Bool
forall a. Eq a => a -> a -> Bool
==)eof ::ReadP ()-- ^ Succeeds iff we are at the end of inputeof :: ReadP ()
eof =do{String
s <-ReadP String
look ;ifString -> Bool
forall a. [a] -> Bool
null String
s then() -> ReadP ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()elseReadP ()
forall a. ReadP a
pfail }string ::String ->ReadP String -- ^ Parses and returns the specified string.string :: String -> ReadP String
string this :: String
this =doString
s <-ReadP String
look ;String -> String -> ReadP String
forall a. Eq a => [a] -> [a] -> ReadP String
scan String
this String
s wherescan :: [a] -> [a] -> ReadP String
scan []_=doString -> ReadP String
forall (m :: * -> *) a. Monad m => a -> m a
return String
this scan (x :: a
x :xs :: [a]
xs )(y :: a
y :ys :: [a]
ys )|a
x a -> a -> Bool
forall a. Eq a => a -> a -> Bool
==a
y =doChar
_<-ReadP Char
get ;[a] -> [a] -> ReadP String
scan [a]
xs [a]
ys scan __=doReadP String
forall a. ReadP a
pfail munch ::(Char->Bool)->ReadP String -- ^ Parses the first zero or more characters satisfying the predicate.-- Always succeeds, exactly once having consumed all the characters-- Hence NOT the same as (many (satisfy p))munch :: (Char -> Bool) -> ReadP String
munch p :: Char -> Bool
p =doString
s <-ReadP String
look String -> ReadP String
scan String
s wherescan :: String -> ReadP String
scan (c :: Char
c :cs :: String
cs )|Char -> Bool
p Char
c =doChar
_<-ReadP Char
get ;String
s <-String -> ReadP String
scan String
cs ;String -> ReadP String
forall (m :: * -> *) a. Monad m => a -> m a
return (Char
c Char -> String -> String
forall a. a -> [a] -> [a]
:String
s )scan _=doString -> ReadP String
forall (m :: * -> *) a. Monad m => a -> m a
return ""munch1 ::(Char->Bool)->ReadP String -- ^ Parses the first one or more characters satisfying the predicate.-- Fails if none, else succeeds exactly once having consumed all the characters-- Hence NOT the same as (many1 (satisfy p))munch1 :: (Char -> Bool) -> ReadP String
munch1 p :: Char -> Bool
p =doChar
c <-ReadP Char
get ifChar -> Bool
p Char
c thendoString
s <-(Char -> Bool) -> ReadP String
munch Char -> Bool
p ;String -> ReadP String
forall (m :: * -> *) a. Monad m => a -> m a
return (Char
c Char -> String -> String
forall a. a -> [a] -> [a]
:String
s )elseReadP String
forall a. ReadP a
pfail choice ::[ReadP a ]->ReadP a -- ^ Combines all parsers in the specified list.choice :: [ReadP a] -> ReadP a
choice []=ReadP a
forall a. ReadP a
pfail choice [p :: ReadP a
p ]=ReadP a
p choice (p :: ReadP a
p :ps :: [ReadP a]
ps )=ReadP a
p ReadP a -> ReadP a -> ReadP a
forall a. ReadP a -> ReadP a -> ReadP a
+++ [ReadP a] -> ReadP a
forall a. [ReadP a] -> ReadP a
choice [ReadP a]
ps skipSpaces ::ReadP ()-- ^ Skips all whitespace.skipSpaces :: ReadP ()
skipSpaces =doString
s <-ReadP String
look String -> ReadP ()
skip String
s whereskip :: String -> ReadP ()
skip (c :: Char
c :s :: String
s )|Char -> Bool
isSpace Char
c =doChar
_<-ReadP Char
get ;String -> ReadP ()
skip String
s skip _=do() -> ReadP ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()count ::Int->ReadP a ->ReadP [a ]-- ^ @count n p@ parses @n@ occurrences of @p@ in sequence. A list of-- results is returned.count :: Int -> ReadP a -> ReadP [a]
count n :: Int
n p :: ReadP a
p =[ReadP a] -> ReadP [a]
forall (m :: * -> *) a. Monad m => [m a] -> m [a]
sequence (Int -> ReadP a -> [ReadP a]
forall a. Int -> a -> [a]
replicate Int
n ReadP a
p )between ::ReadP open ->ReadP close ->ReadP a ->ReadP a -- ^ @between open close p@ parses @open@, followed by @p@ and finally-- @close@. Only the value of @p@ is returned.between :: ReadP open -> ReadP close -> ReadP a -> ReadP a
between open :: ReadP open
open close :: ReadP close
close p :: ReadP a
p =doopen
_<-ReadP open
open a
x <-ReadP a
p close
_<-ReadP close
close a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x option ::a ->ReadP a ->ReadP a -- ^ @option x p@ will either parse @p@ or return @x@ without consuming-- any input.option :: a -> ReadP a -> ReadP a
option x :: a
x p :: ReadP a
p =ReadP a
p ReadP a -> ReadP a -> ReadP a
forall a. ReadP a -> ReadP a -> ReadP a
+++ a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x optional ::ReadP a ->ReadP ()-- ^ @optional p@ optionally parses @p@ and always returns @()@.optional :: ReadP a -> ReadP ()
optional p :: ReadP a
p =(ReadP a
p ReadP a -> ReadP () -> ReadP ()
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> () -> ReadP ()
forall (m :: * -> *) a. Monad m => a -> m a
return ())ReadP () -> ReadP () -> ReadP ()
forall a. ReadP a -> ReadP a -> ReadP a
+++ () -> ReadP ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()many ::ReadP a ->ReadP [a ]-- ^ Parses zero or more occurrences of the given parser.many :: ReadP a -> ReadP [a]
many p :: ReadP a
p =[a] -> ReadP [a]
forall (m :: * -> *) a. Monad m => a -> m a
return []ReadP [a] -> ReadP [a] -> ReadP [a]
forall a. ReadP a -> ReadP a -> ReadP a
+++ ReadP a -> ReadP [a]
forall a. ReadP a -> ReadP [a]
many1 ReadP a
p many1 ::ReadP a ->ReadP [a ]-- ^ Parses one or more occurrences of the given parser.many1 :: ReadP a -> ReadP [a]
many1 p :: ReadP a
p =(a -> [a] -> [a]) -> ReadP a -> ReadP [a] -> ReadP [a]
forall (m :: * -> *) a1 a2 r.
Monad m =>
(a1 -> a2 -> r) -> m a1 -> m a2 -> m r
liftM2 (:)ReadP a
p (ReadP a -> ReadP [a]
forall a. ReadP a -> ReadP [a]
many ReadP a
p )skipMany ::ReadP a ->ReadP ()-- ^ Like 'many', but discards the result.skipMany :: ReadP a -> ReadP ()
skipMany p :: ReadP a
p =ReadP a -> ReadP [a]
forall a. ReadP a -> ReadP [a]
many ReadP a
p ReadP [a] -> ReadP () -> ReadP ()
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> () -> ReadP ()
forall (m :: * -> *) a. Monad m => a -> m a
return ()skipMany1 ::ReadP a ->ReadP ()-- ^ Like 'many1', but discards the result.skipMany1 :: ReadP a -> ReadP ()
skipMany1 p :: ReadP a
p =ReadP a
p ReadP a -> ReadP () -> ReadP ()
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> ReadP a -> ReadP ()
forall a. ReadP a -> ReadP ()
skipMany ReadP a
p sepBy ::ReadP a ->ReadP sep ->ReadP [a ]-- ^ @sepBy p sep@ parses zero or more occurrences of @p@, separated by @sep@.-- Returns a list of values returned by @p@.sepBy :: ReadP a -> ReadP sep -> ReadP [a]
sepBy p :: ReadP a
p sep :: ReadP sep
sep =ReadP a -> ReadP sep -> ReadP [a]
forall a sep. ReadP a -> ReadP sep -> ReadP [a]
sepBy1 ReadP a
p ReadP sep
sep ReadP [a] -> ReadP [a] -> ReadP [a]
forall a. ReadP a -> ReadP a -> ReadP a
+++ [a] -> ReadP [a]
forall (m :: * -> *) a. Monad m => a -> m a
return []sepBy1 ::ReadP a ->ReadP sep ->ReadP [a ]-- ^ @sepBy1 p sep@ parses one or more occurrences of @p@, separated by @sep@.-- Returns a list of values returned by @p@.sepBy1 :: ReadP a -> ReadP sep -> ReadP [a]
sepBy1 p :: ReadP a
p sep :: ReadP sep
sep =(a -> [a] -> [a]) -> ReadP a -> ReadP [a] -> ReadP [a]
forall (m :: * -> *) a1 a2 r.
Monad m =>
(a1 -> a2 -> r) -> m a1 -> m a2 -> m r
liftM2 (:)ReadP a
p (ReadP a -> ReadP [a]
forall a. ReadP a -> ReadP [a]
many (ReadP sep
sep ReadP sep -> ReadP a -> ReadP a
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> ReadP a
p ))endBy ::ReadP a ->ReadP sep ->ReadP [a ]-- ^ @endBy p sep@ parses zero or more occurrences of @p@, separated and ended-- by @sep@.endBy :: ReadP a -> ReadP sep -> ReadP [a]
endBy p :: ReadP a
p sep :: ReadP sep
sep =ReadP a -> ReadP [a]
forall a. ReadP a -> ReadP [a]
many (doa
x <-ReadP a
p ;sep
_<-ReadP sep
sep ;a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x )endBy1 ::ReadP a ->ReadP sep ->ReadP [a ]-- ^ @endBy p sep@ parses one or more occurrences of @p@, separated and ended-- by @sep@.endBy1 :: ReadP a -> ReadP sep -> ReadP [a]
endBy1 p :: ReadP a
p sep :: ReadP sep
sep =ReadP a -> ReadP [a]
forall a. ReadP a -> ReadP [a]
many1 (doa
x <-ReadP a
p ;sep
_<-ReadP sep
sep ;a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x )chainr ::ReadP a ->ReadP (a ->a ->a )->a ->ReadP a -- ^ @chainr p op x@ parses zero or more occurrences of @p@, separated by @op@.-- Returns a value produced by a /right/ associative application of all-- functions returned by @op@. If there are no occurrences of @p@, @x@ is-- returned.chainr :: ReadP a -> ReadP (a -> a -> a) -> a -> ReadP a
chainr p :: ReadP a
p op :: ReadP (a -> a -> a)
op x :: a
x =ReadP a -> ReadP (a -> a -> a) -> ReadP a
forall a. ReadP a -> ReadP (a -> a -> a) -> ReadP a
chainr1 ReadP a
p ReadP (a -> a -> a)
op ReadP a -> ReadP a -> ReadP a
forall a. ReadP a -> ReadP a -> ReadP a
+++ a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x chainl ::ReadP a ->ReadP (a ->a ->a )->a ->ReadP a -- ^ @chainl p op x@ parses zero or more occurrences of @p@, separated by @op@.-- Returns a value produced by a /left/ associative application of all-- functions returned by @op@. If there are no occurrences of @p@, @x@ is-- returned.chainl :: ReadP a -> ReadP (a -> a -> a) -> a -> ReadP a
chainl p :: ReadP a
p op :: ReadP (a -> a -> a)
op x :: a
x =ReadP a -> ReadP (a -> a -> a) -> ReadP a
forall a. ReadP a -> ReadP (a -> a -> a) -> ReadP a
chainl1 ReadP a
p ReadP (a -> a -> a)
op ReadP a -> ReadP a -> ReadP a
forall a. ReadP a -> ReadP a -> ReadP a
+++ a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x chainr1 ::ReadP a ->ReadP (a ->a ->a )->ReadP a -- ^ Like 'chainr', but parses one or more occurrences of @p@.chainr1 :: ReadP a -> ReadP (a -> a -> a) -> ReadP a
chainr1 p :: ReadP a
p op :: ReadP (a -> a -> a)
op =ReadP a
scan wherescan :: ReadP a
scan =ReadP a
p ReadP a -> (a -> ReadP a) -> ReadP a
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= a -> ReadP a
rest rest :: a -> ReadP a
rest x :: a
x =doa -> a -> a
f <-ReadP (a -> a -> a)
op a
y <-ReadP a
scan a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return (a -> a -> a
f a
x a
y )ReadP a -> ReadP a -> ReadP a
forall a. ReadP a -> ReadP a -> ReadP a
+++ a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x chainl1 ::ReadP a ->ReadP (a ->a ->a )->ReadP a -- ^ Like 'chainl', but parses one or more occurrences of @p@.chainl1 :: ReadP a -> ReadP (a -> a -> a) -> ReadP a
chainl1 p :: ReadP a
p op :: ReadP (a -> a -> a)
op =ReadP a
p ReadP a -> (a -> ReadP a) -> ReadP a
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= a -> ReadP a
rest whererest :: a -> ReadP a
rest x :: a
x =doa -> a -> a
f <-ReadP (a -> a -> a)
op a
y <-ReadP a
p a -> ReadP a
rest (a -> a -> a
f a
x a
y )ReadP a -> ReadP a -> ReadP a
forall a. ReadP a -> ReadP a -> ReadP a
+++ a -> ReadP a
forall (m :: * -> *) a. Monad m => a -> m a
return a
x manyTill ::ReadP a ->ReadP end ->ReadP [a ]-- ^ @manyTill p end@ parses zero or more occurrences of @p@, until @end@-- succeeds. Returns a list of values returned by @p@.manyTill :: ReadP a -> ReadP end -> ReadP [a]
manyTill p :: ReadP a
p end :: ReadP end
end =ReadP [a]
scan wherescan :: ReadP [a]
scan =(ReadP end
end ReadP end -> ReadP [a] -> ReadP [a]
forall (m :: * -> *) a b. Monad m => m a -> m b -> m b
>> [a] -> ReadP [a]
forall (m :: * -> *) a. Monad m => a -> m a
return [])ReadP [a] -> ReadP [a] -> ReadP [a]
forall a. ReadP a -> ReadP a -> ReadP a
<++ ((a -> [a] -> [a]) -> ReadP a -> ReadP [a] -> ReadP [a]
forall (m :: * -> *) a1 a2 r.
Monad m =>
(a1 -> a2 -> r) -> m a1 -> m a2 -> m r
liftM2 (:)ReadP a
p ReadP [a]
scan )-- ----------------------------------------------------------------------------- Converting between ReadP and ReadreadP_to_S ::ReadP a ->ReadS a -- ^ Converts a parser into a Haskell ReadS-style function.-- This is the main way in which you can \"run\" a 'ReadP' parser:-- the expanded type is-- @ readP_to_S :: ReadP a -> String -> [(a,String)] @readP_to_S :: ReadP a -> ReadS a
readP_to_S (R f :: forall b. (a -> P b) -> P b
f )=P a -> ReadS a
forall a. P a -> ReadS a
run ((a -> P a) -> P a
forall b. (a -> P b) -> P b
f a -> P a
forall (m :: * -> *) a. Monad m => a -> m a
return )readS_to_P ::ReadS a ->ReadP a -- ^ Converts a Haskell ReadS-style function into a parser.-- Warning: This introduces local backtracking in the resulting-- parser, and therefore a possible inefficiency.readS_to_P :: ReadS a -> ReadP a
readS_to_P r :: ReadS a
r =(forall b. (a -> P b) -> P b) -> ReadP a
forall a. (forall b. (a -> P b) -> P b) -> ReadP a
R (\k :: a -> P b
k ->(String -> P b) -> P b
forall a. (String -> P a) -> P a
Look (\s :: String
s ->[(b, String)] -> P b
forall a. [(a, String)] -> P a
final [(b, String)
bs'' |(a :: a
a ,s' :: String
s' )<-ReadS a
r String
s ,(b, String)
bs'' <-P b -> ReadS b
forall a. P a -> ReadS a
run (a -> P b
k a
a )String
s' ]))-- ----------------------------------------------------------------------------- QuickCheck properties that hold for the combinators{- $properties
The following are QuickCheck specifications of what the combinators do.
These can be seen as formal specifications of the behavior of the
combinators.
For some values, we only care about the lists contents, not their order,
> (=~) :: Ord a => [a] -> [a] -> Bool
> xs =~ ys = sort xs == sort ys
Here follow the properties:
>>> readP_to_S get []
[]
prop> \c str -> readP_to_S get (c:str) == [(c, str)]
prop> \str -> readP_to_S look str == [(str, str)]
prop> \str -> readP_to_S pfail str == []
prop> \x str -> readP_to_S (return x) s == [(x,s)]
> prop_Bind p k s =
> readP_to_S (p >>= k) s =~
> [ ys''
> | (x,s') <- readP_to_S p s
> , ys'' <- readP_to_S (k (x::Int)) s'
> ]
> prop_Plus p q s =
> readP_to_S (p +++ q) s =~
> (readP_to_S p s ++ readP_to_S q s)
> prop_LeftPlus p q s =
> readP_to_S (p <++ q) s =~
> (readP_to_S p s +<+ readP_to_S q s)
> where
> [] +<+ ys = ys
> xs +<+ _ = xs
> prop_Gather s =
> forAll readPWithoutReadS $ \p ->
> readP_to_S (gather p) s =~
> [ ((pre,x::Int),s')
> | (x,s') <- readP_to_S p s
> , let pre = take (length s - length s') s
> ]
prop> \this str -> readP_to_S (string this) (this ++ str) == [(this,str)]
> prop_String_Maybe this s =
> readP_to_S (string this) s =~
> [(this, drop (length this) s) | this `isPrefixOf` s]
> prop_Munch p s =
> readP_to_S (munch p) s =~
> [(takeWhile p s, dropWhile p s)]
> prop_Munch1 p s =
> readP_to_S (munch1 p) s =~
> [(res,s') | let (res,s') = (takeWhile p s, dropWhile p s), not (null res)]
> prop_Choice ps s =
> readP_to_S (choice ps) s =~
> readP_to_S (foldr (+++) pfail ps) s
> prop_ReadS r s =
> readP_to_S (readS_to_P r) s =~ r s
-}