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{- This Source Code Form is subject to the terms of the Mozilla Public License,
v. 2.0. If a copy of the MPL was not distributed with this file, You can
obtain one at https://mozilla.org/MPL/2.0/. -}
{-# LANGUAGE OverloadedStrings #-}
-- | ToGraphQL and FromGraphQL typeclasses used for user-defined type
-- conversion.
module Language.GraphQL.Class
( FromGraphQL(..)
, ToGraphQL(..)
) where
import Data.Foldable (toList)
import Data.Int (Int8, Int16, Int32, Int64)
import Data.Text (Text)
import Data.Word (Word8, Word16, Word32, Word64)
import qualified Data.Text.Read as Text.Read
import Data.Vector (Vector)
import qualified Data.Vector as Vector
import qualified Language.GraphQL.Type as Type
import Data.Scientific (Scientific, toRealFloat)
fromGraphQLToIntegral :: Integral a => Type.Value -> Maybe a
fromGraphQLToIntegral (Type.Int value) = Just $ fromIntegral value
fromGraphQLToIntegral (Type.String value) =
case Text.Read.decimal value of
Right (converted, "") -> Just converted
_conversionError -> Nothing
fromGraphQLToIntegral _ = Nothing
-- | Instances of this typeclass can be converted to GraphQL internal
-- representation.
class ToGraphQL a
where
toGraphQL :: a -> Type.Value
instance ToGraphQL Text
where
toGraphQL = Type.String
instance ToGraphQL Int
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL Int8
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL Int16
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL Int32
where
toGraphQL = Type.Int
instance ToGraphQL Int64
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL Word
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL Word8
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL Word16
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL Word32
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL Word64
where
toGraphQL = Type.Int . fromIntegral
instance ToGraphQL a => ToGraphQL [a]
where
toGraphQL = Type.List . fmap toGraphQL
instance ToGraphQL a => ToGraphQL (Vector a)
where
toGraphQL = Type.List . toList . fmap toGraphQL
instance ToGraphQL a => ToGraphQL (Maybe a)
where
toGraphQL (Just justValue) = toGraphQL justValue
toGraphQL Nothing = Type.Null
instance ToGraphQL Bool
where
toGraphQL = Type.Boolean
instance ToGraphQL Float
where
toGraphQL = Type.Float . realToFrac
instance ToGraphQL Double
where
toGraphQL = Type.Float
instance ToGraphQL Scientific
where
toGraphQL = Type.Float . toRealFloat
-- | Instances of this typeclass can be used to convert GraphQL internal
-- representation to user-defined type.
class FromGraphQL a
where
fromGraphQL :: Type.Value -> Maybe a
instance FromGraphQL Text
where
fromGraphQL (Type.String value) = Just value
fromGraphQL _ = Nothing
instance FromGraphQL Int
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Int8
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Int16
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Int32
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Int64
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Word
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Word8
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Word16
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Word32
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL Word64
where
fromGraphQL = fromGraphQLToIntegral
instance FromGraphQL a => FromGraphQL [a]
where
fromGraphQL (Type.List value) = traverse fromGraphQL value
fromGraphQL _ = Nothing
instance FromGraphQL a => FromGraphQL (Vector a)
where
fromGraphQL (Type.List value) = Vector.fromList
<$> traverse fromGraphQL value
fromGraphQL _ = Nothing
instance FromGraphQL a => FromGraphQL (Maybe a)
where
fromGraphQL Type.Null = Just Nothing
fromGraphQL value = Just <$> fromGraphQL value
instance FromGraphQL Bool
where
fromGraphQL (Type.Boolean value) = Just value
fromGraphQL _ = Nothing
instance FromGraphQL Float
where
fromGraphQL (Type.Float value) = Just $ realToFrac value
fromGraphQL _ = Nothing
instance FromGraphQL Double
where
fromGraphQL (Type.Float value) = Just value
fromGraphQL _ = Nothing
instance FromGraphQL Scientific
where
fromGraphQL (Type.Float value) = Just $ realToFrac value
fromGraphQL _ = Nothing
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