{-# LANGUAGE CPP #-}
{-# LANGUAGE OverloadedStrings #-}
{-# OPTIONS_GHC -fno-warn-orphans #-}
module Data.Can.Aeson where
import Data.Aeson
import Data.Aeson.Encoding (emptyObject_, pair)
import qualified Data.HashMap.Lazy as HM
import Data.Can (Can(..))
#if __GLASGOW_HASKELL__ < 804
import Data.Semigroup (Semigroup(..))
#endif
instance (ToJSON a, ToJSON b) => ToJSON (Can a b) where
toJSON Non = object []
toJSON (One a) = object [ "One" .= a ]
toJSON (Eno b) = object [ "Eno" .= b ]
toJSON (Two a b) = object [ "One" .= a, "Eno" .= b ]
toEncoding (One a) = pairs $ "One" .= a
toEncoding (Eno b) = pairs $ "Eno" .= b
toEncoding (Two a b) = pairs $ "One" .= a <> "Eno" .= b
toEncoding Non = emptyObject_
instance (FromJSON a, FromJSON b) => FromJSON (Can a b) where
parseJSON = withObject "Can a b" (go . HM.toList)
where
go [("One", a)] = One <$> parseJSON a
go [("Eno", b)] = Eno <$> parseJSON b
go [("One", a), ("Eno", b)] = Two <$> parseJSON a <*> parseJSON b
go [] = pure Non
go _ = fail "Expected either empty object, or 'One' and 'Eno' keys, 'One' or 'Eno' keys only"
instance ToJSON2 Can where
liftToJSON2 f _ _ _ (One a) = object [ "One" .= f a ]
liftToJSON2 _ _ g _ (Eno b) = object [ "Eno" .= g b ]
liftToJSON2 f _ g _ (Two a b) = object [ "One" .= f a, "Eno" .= g b ]
liftToJSON2 _ _ _ _ Non = object []
liftToEncoding2 f _ _ _ (One a) = pairs $ pair "One" (f a)
liftToEncoding2 _ _ g _ (Eno b) = pairs $ pair "Eno" (g b)
liftToEncoding2 f _ g _ (Two a b) = pairs $ pair "One" (f a) <> pair "Eno" (g b)
liftToEncoding2 _ _ _ _ Non = emptyObject_
instance ToJSON a => ToJSON1 (Can a) where
liftToJSON _ _ (One a) = object [ "One" .= a ]
liftToJSON g _ (Eno b) = object [ "Eno" .= g b ]
liftToJSON g _ (Two a b) = object [ "One" .= a, "Eno" .= g b ]
liftToJSON _ _ Non = object []
liftToEncoding _ _ (One a) = pairs $ "One" .= a
liftToEncoding g _ (Eno b) = pairs $ pair "Eno" (g b)
liftToEncoding g _ (Two a b) = pairs $ "One" .= a <> pair "Eno" (g b)
liftToEncoding _ _ Non = emptyObject_
instance FromJSON2 Can where
liftParseJSON2 f _ g _ = withObject "Can a b" (go . HM.toList)
where
go [] = pure Non
go [("One", a)] = One <$> f a
go [("Eno", b)] = Eno <$> g b
go [("One", a), ("Eno", b)] = Two <$> f a <*> g b
go _ = fail "Expected either empty object, or 'One' and 'Eno' keys, 'One' or 'Eno' keys only"
instance FromJSON a => FromJSON1 (Can a) where
liftParseJSON f _ = withObject "Can a b" (go . HM.toList)
where
go [] = pure Non
go [("One", a)] = One <$> parseJSON a
go [("Eno", b)] = Eno <$> f b
go [("One", a), ("Eno", b)] = Two <$> parseJSON a <*> f b
go _ = fail "Expected either empty object, or 'One' and 'Eno' keys, 'One' or 'Eno' keys only"