{-# LANGUAGE CPP #-}
#if __GLASGOW_HASKELL__ >= 702
{-# LANGUAGE Trustworthy #-} -- Imports internal modules
#endif

-- |
-- Module      :  Data.Attoparsec.ByteString.Lazy
-- Copyright   :  Bryan O'Sullivan 2007-2015
-- License     :  BSD3
--
-- Maintainer  :  [email protected]
-- Stability   :  experimental
-- Portability :  unknown
--
-- Simple, efficient combinator parsing that can consume lazy
-- 'ByteString' strings, loosely based on the Parsec library.
--
-- This is essentially the same code as in the 'Data.Attoparsec'
-- module, only with a 'parse' function that can consume a lazy
-- 'ByteString' incrementally, and a 'Result' type that does not allow
-- more input to be fed in.  Think of this as suitable for use with a
-- lazily read file, e.g. via 'L.readFile' or 'L.hGetContents'.
--
-- /Note:/ The various parser functions and combinators such as
-- 'string' still expect /strict/ 'B.ByteString' parameters, and
-- return strict 'B.ByteString' results.  Behind the scenes, strict
-- 'B.ByteString' values are still used internally to store parser
-- input and manipulate it efficiently.

module Data.Attoparsec.ByteString.Lazy
    (
      Result(..)
    , module Data.Attoparsec.ByteString
    -- * Running parsers
    , parse
    , parseOnly
    , parseTest
    -- ** Result conversion
    , maybeResult
    , eitherResult
    ) where

import Control.DeepSeq (NFData(rnf))
import Data.ByteString.Lazy.Internal (ByteString(..), chunk)
import Data.List (intercalate)
import qualified Data.ByteString as B
import qualified Data.Attoparsec.ByteString as A
import qualified Data.Attoparsec.Internal.Types as T
import Data.Attoparsec.ByteString
    hiding (IResult(..), Result, eitherResult, maybeResult,
            parse, parseOnly, parseWith, parseTest)

-- | The result of a parse.
data Result r = Fail ByteString [String] String
              -- ^ The parse failed.  The 'ByteString' is the input
              -- that had not yet been consumed when the failure
              -- occurred.  The @[@'String'@]@ is a list of contexts
              -- in which the error occurred.  The 'String' is the
              -- message describing the error, if any.
              | Done ByteString r
              -- ^ The parse succeeded.  The 'ByteString' is the
              -- input that had not yet been consumed (if any) when
              -- the parse succeeded.

instance NFData r => NFData (Result r) where
    rnf :: Result r -> ()
rnf (Fail ByteString
bs [String]
ctxs String
msg) = ByteString -> ()
rnfBS ByteString
bs seq :: forall a b. a -> b -> b
`seq` forall a. NFData a => a -> ()
rnf [String]
ctxs seq :: forall a b. a -> b -> b
`seq` forall a. NFData a => a -> ()
rnf String
msg
    rnf (Done ByteString
bs r
r)        = ByteString -> ()
rnfBS ByteString
bs seq :: forall a b. a -> b -> b
`seq` forall a. NFData a => a -> ()
rnf r
r
    {-# INLINE rnf #-}

rnfBS :: ByteString -> ()
rnfBS :: ByteString -> ()
rnfBS (Chunk ByteString
_ ByteString
xs) = ByteString -> ()
rnfBS ByteString
xs
rnfBS ByteString
Empty        = ()
{-# INLINE rnfBS #-}

instance Show r => Show (Result r) where
    show :: Result r -> String
show (Fail ByteString
bs [String]
stk String
msg) =
        String
"Fail " forall a. [a] -> [a] -> [a]
++ forall a. Show a => a -> String
show ByteString
bs forall a. [a] -> [a] -> [a]
++ String
" " forall a. [a] -> [a] -> [a]
++ forall a. Show a => a -> String
show [String]
stk forall a. [a] -> [a] -> [a]
++ String
" " forall a. [a] -> [a] -> [a]
++ forall a. Show a => a -> String
show String
msg
    show (Done ByteString
bs r
r)       = String
"Done " forall a. [a] -> [a] -> [a]
++ forall a. Show a => a -> String
show ByteString
bs forall a. [a] -> [a] -> [a]
++ String
" " forall a. [a] -> [a] -> [a]
++ forall a. Show a => a -> String
show r
r

fmapR :: (a -> b) -> Result a -> Result b
fmapR :: forall a b. (a -> b) -> Result a -> Result b
fmapR a -> b
_ (Fail ByteString
st [String]
stk String
msg) = forall r. ByteString -> [String] -> String -> Result r
Fail ByteString
st [String]
stk String
msg
fmapR a -> b
f (Done ByteString
bs a
r)       = forall r. ByteString -> r -> Result r
Done ByteString
bs (a -> b
f a
r)

instance Functor Result where
    fmap :: forall a b. (a -> b) -> Result a -> Result b
fmap = forall a b. (a -> b) -> Result a -> Result b
fmapR

-- | Run a parser and return its result.
parse :: A.Parser a -> ByteString -> Result a
parse :: forall a. Parser a -> ByteString -> Result a
parse Parser a
p ByteString
s = case ByteString
s of
              Chunk ByteString
x ByteString
xs -> forall {r}. IResult ByteString r -> ByteString -> Result r
go (forall a. Parser a -> ByteString -> Result a
A.parse Parser a
p ByteString
x) ByteString
xs
              ByteString
empty      -> forall {r}. IResult ByteString r -> ByteString -> Result r
go (forall a. Parser a -> ByteString -> Result a
A.parse Parser a
p ByteString
B.empty) ByteString
empty
  where
    go :: IResult ByteString r -> ByteString -> Result r
go (T.Fail ByteString
x [String]
stk String
msg) ByteString
ys      = forall r. ByteString -> [String] -> String -> Result r
Fail (ByteString -> ByteString -> ByteString
chunk ByteString
x ByteString
ys) [String]
stk String
msg
    go (T.Done ByteString
x r
r) ByteString
ys            = forall r. ByteString -> r -> Result r
Done (ByteString -> ByteString -> ByteString
chunk ByteString
x ByteString
ys) r
r
    go (T.Partial ByteString -> IResult ByteString r
k) (Chunk ByteString
y ByteString
ys) = IResult ByteString r -> ByteString -> Result r
go (ByteString -> IResult ByteString r
k ByteString
y) ByteString
ys
    go (T.Partial ByteString -> IResult ByteString r
k) ByteString
empty        = IResult ByteString r -> ByteString -> Result r
go (ByteString -> IResult ByteString r
k ByteString
B.empty) ByteString
empty

-- | Run a parser and print its result to standard output.
parseTest :: (Show a) => A.Parser a -> ByteString -> IO ()
parseTest :: forall a. Show a => Parser a -> ByteString -> IO ()
parseTest Parser a
p ByteString
s = forall a. Show a => a -> IO ()
print (forall a. Parser a -> ByteString -> Result a
parse Parser a
p ByteString
s)

-- | Convert a 'Result' value to a 'Maybe' value.
maybeResult :: Result r -> Maybe r
maybeResult :: forall r. Result r -> Maybe r
maybeResult (Done ByteString
_ r
r) = forall a. a -> Maybe a
Just r
r
maybeResult Result r
_          = forall a. Maybe a
Nothing

-- | Convert a 'Result' value to an 'Either' value.
eitherResult :: Result r -> Either String r
eitherResult :: forall r. Result r -> Either String r
eitherResult (Done ByteString
_ r
r)        = forall a b. b -> Either a b
Right r
r
eitherResult (Fail ByteString
_ [] String
msg)   = forall a b. a -> Either a b
Left String
msg
eitherResult (Fail ByteString
_ [String]
ctxs String
msg) = forall a b. a -> Either a b
Left (forall a. [a] -> [[a]] -> [a]
intercalate String
" > " [String]
ctxs forall a. [a] -> [a] -> [a]
++ String
": " forall a. [a] -> [a] -> [a]
++ String
msg)

-- | Run a parser that cannot be resupplied via a 'T.Partial' result.
--
-- This function does not force a parser to consume all of its input.
-- Instead, any residual input will be discarded.  To force a parser
-- to consume all of its input, use something like this:
--
-- @
--'parseOnly' (myParser 'Control.Applicative.<*' 'endOfInput')
-- @
parseOnly :: A.Parser a -> ByteString -> Either String a
parseOnly :: forall a. Parser a -> ByteString -> Either String a
parseOnly Parser a
p = forall r. Result r -> Either String r
eitherResult forall b c a. (b -> c) -> (a -> b) -> a -> c
. forall a. Parser a -> ByteString -> Result a
parse Parser a
p
{-# INLINE parseOnly #-}