{-# LANGUAGE MultiParamTypeClasses,
TypeSynonymInstances,
FlexibleInstances,
FunctionalDependencies #-}
-- |
-- Module : Test.Hspec.Attoparsec.Source
-- Copyright : (c) 2014 Alp Mestanogullari
-- License : BSD3
-- Maintainer : alpmestan@gmail.com
-- Stability : experimental
--
-- A 'Source' class that ties parser types and input types to
-- give you a uniform interface for testing your parsers,
-- without caring about the input type.
module Test.Hspec.Attoparsec.Source where
import qualified Data.Attoparsec.ByteString as AB
import qualified Data.ByteString as B
import qualified Data.Attoparsec.ByteString.Lazy as ALB
import qualified Data.ByteString.Lazy as LB
import qualified Data.Attoparsec.Text as AT
import qualified Data.Text as T
import qualified Data.Attoparsec.Text.Lazy as ALT
import qualified Data.Text.Lazy as LT
import qualified Data.Attoparsec.Types as Atto
import Data.String (IsString)
-- | A class where each instance will just teach
-- how to get an Either or the specific result
-- type associated to the parser for the given
-- input type.
class (Eq string, Show string, IsString string)
=> Source parser string string' result | string -> parser, string -> result, string -> string' where
-- | Feed some input to a parser and extract the result
-- as either a failure 'String' or an actually parsed value.
-- Can be read as /fed to/.
--
-- > -- "" fed to an HTML parser
-- > "Go to foo" ~> htmlParser :: Either String a
(~>) :: string -> parser string' a -> Either String a
-- | Feed some input to a parser and extract it as the
-- appropriate result type from that module.
--
-- This is not currently useful in the library per se,
-- but is used in test-suites directly where we generally only deal
-- with one concrete set of parser, input and result types.
-- This lets us inspect the result in any way we want, e.g
-- in conjunction with @shouldSatisfy@ or a custom hspec combinator.
(~?>) :: string -> parser string' a -> result a
instance Source Atto.Parser B.ByteString B.ByteString AB.Result where
t ~> p = AB.parseOnly p t
t ~?> p = AB.parse p t
instance Source Atto.Parser LB.ByteString B.ByteString ALB.Result where
t ~> p = ALB.eitherResult $ t ~?> p
t ~?> p = ALB.parse p t
instance Source Atto.Parser T.Text T.Text AT.Result where
t ~> p = AT.parseOnly p t
t ~?> p = AT.parse p t
instance Source Atto.Parser LT.Text T.Text ALT.Result where
t ~> p = ALT.eitherResult $ t ~?> p
t ~?> p = ALT.parse p t
-- | Class for generically inspecting unconsumed input
class Leftover r s | r -> s where
-- | Get the unconsumed input from the result of a parser
--
-- Returns 'Nothing' if the unconsumed input is ""
leftover :: r a -> Maybe s
instance Leftover AB.Result B.ByteString where
leftover (AB.Done t _) = Just t
leftover _ = Nothing
instance Leftover ALB.Result LB.ByteString where
leftover (ALB.Done t _) = Just t
leftover _ = Nothing
instance Leftover AT.Result T.Text where
leftover (AT.Done t _) = Just t
leftover _ = Nothing
instance Leftover ALT.Result LT.Text where
leftover (ALT.Done t _) = Just t
leftover _ = Nothing