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FromValue.hs
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FromValue.hs
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{-# LANGUAGE DefaultSignatures #-}
{-# LANGUAGE FlexibleContexts #-}
{-# LANGUAGE FlexibleInstances #-}
{-# LANGUAGE ScopedTypeVariables #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE TypeOperators #-}
{-# LANGUAGE StandaloneDeriving #-}
{-# LANGUAGE RecordWildCards #-}
{-# LANGUAGE ConstraintKinds #-}
{-# LANGUAGE DataKinds #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE TypeApplications #-}
{-# LANGUAGE DeriveFunctor #-}
module Data.Aeson.Config.FromValue (
FromValue(..)
, Parser
, Result
, decodeValue
, Generic
, GenericDecode
, genericFromValue
, Options(..)
, genericFromValueWith
, typeMismatch
, withObject
, withText
, withString
, withArray
, withNumber
, withBool
, parseArray
, traverseObject
, (.:)
, (.:?)
, Key
, Value(..)
, Object
, Array
, Alias(..)
, unAlias
) where
import Imports
import Data.Monoid (Last(..))
import GHC.Generics
import GHC.TypeLits
import Data.Proxy
import Data.Map.Lazy (Map)
import qualified Data.Map.Lazy as Map
import qualified Data.Vector as V
import Data.Aeson.Config.Key (Key)
import qualified Data.Aeson.Config.Key as Key
import Data.Aeson.Config.KeyMap (member)
import qualified Data.Aeson.Config.KeyMap as KeyMap
import Data.Aeson.Types (FromJSON(..))
import Data.Aeson.Config.Util
import Data.Aeson.Config.Parser
type Result a = Either String (a, [String], [(String, String)])
decodeValue :: FromValue a => Value -> Result a
decodeValue = runParser fromValue
(.:) :: FromValue a => Object -> Key -> Parser a
(.:) = explicitParseField fromValue
(.:?) :: FromValue a => Object -> Key -> Parser (Maybe a)
(.:?) = explicitParseFieldMaybe fromValue
class FromValue a where
fromValue :: Value -> Parser a
default fromValue :: forall d m. (Generic a, Rep a ~ D1 d m, Datatype d, GenericDecode (Rep a)) => Value -> Parser a
fromValue = genericFromValue
genericFromValue :: forall a d m. (Generic a, Rep a ~ D1 d m, Datatype d, GenericDecode (Rep a)) => Value -> Parser a
genericFromValue = genericFromValueWith (Options $ hyphenize name)
where
name :: String
name = datatypeName (undefined :: D1 d m p)
instance FromValue Bool where
fromValue = liftParser . parseJSON
instance FromValue Int where
fromValue = liftParser . parseJSON
instance FromValue Text where
fromValue = liftParser . parseJSON
instance {-# OVERLAPPING #-} FromValue String where
fromValue = liftParser . parseJSON
instance FromValue a => FromValue (Maybe a) where
fromValue value = liftParser (parseJSON value) >>= traverse fromValue
instance FromValue a => FromValue [a] where
fromValue = withArray (parseArray fromValue)
parseArray :: (Value -> Parser a) -> Array -> Parser [a]
parseArray f = zipWithM (parseIndexed f) [0..] . V.toList
where
parseIndexed :: (Value -> Parser a) -> Int -> Value -> Parser a
parseIndexed p n value = p value <?> Index n
instance FromValue a => FromValue (Map String a) where
fromValue = withObject $ \ o -> do
xs <- traverseObject fromValue o
return $ Map.fromList (map (first Key.toString) xs)
traverseObject :: (Value -> Parser a) -> Object -> Parser [(Key, a)]
traverseObject f o = do
forM (KeyMap.toList o) $ \ (name, value) ->
(,) name <$> f value <?> Key name
instance (FromValue a, FromValue b) => FromValue (a, b) where
fromValue v = (,) <$> fromValue v <*> fromValue v
instance (FromValue a, FromValue b) => FromValue (Either a b) where
fromValue v = Left <$> fromValue v <|> Right <$> fromValue v
data Options = Options {
optionsRecordSelectorModifier :: String -> String
}
genericFromValueWith :: (Generic a, GenericDecode (Rep a)) => Options -> Value -> Parser a
genericFromValueWith opts = fmap to . genericDecode opts
class GenericDecode f where
genericDecode :: Options -> Value -> Parser (f p)
instance (GenericDecode a) => GenericDecode (D1 d a) where
genericDecode opts = fmap M1 . genericDecode opts
instance (GenericDecode a) => GenericDecode (C1 c a) where
genericDecode opts = fmap M1 . genericDecode opts
instance (GenericDecode a, GenericDecode b) => GenericDecode (a :*: b) where
genericDecode opts o = (:*:) <$> genericDecode opts o <*> genericDecode opts o
type RecordField sel a = S1 sel (Rec0 a)
instance (Selector sel, FromValue a) => GenericDecode (RecordField sel a) where
genericDecode = accessFieldWith (.:)
instance {-# OVERLAPPING #-} (Selector sel, FromValue a) => GenericDecode (RecordField sel (Maybe a)) where
genericDecode = accessFieldWith (.:?)
instance {-# OVERLAPPING #-} (Selector sel, FromValue a) => GenericDecode (RecordField sel (Last a)) where
genericDecode = accessFieldWith (\ value key -> Last <$> (value .:? key))
instance {-# OVERLAPPING #-} (Selector sel, FromValue a, KnownBool deprecated, KnownSymbol alias) => GenericDecode (RecordField sel (Alias deprecated alias (Maybe a))) where
genericDecode = accessFieldWith (\ value key -> aliasAccess (.:?) value (Alias key))
instance {-# OVERLAPPING #-} (Selector sel, FromValue a, KnownBool deprecated, KnownSymbol alias) => GenericDecode (RecordField sel (Alias deprecated alias (Last a))) where
genericDecode = accessFieldWith (\ value key -> fmap Last <$> aliasAccess (.:?) value (Alias key))
aliasAccess :: forall deprecated alias a. (KnownBool deprecated, KnownSymbol alias) => (Object -> Key -> Parser a) -> Object -> (Alias deprecated alias Key) -> Parser (Alias deprecated alias a)
aliasAccess op value (Alias key)
| alias `member` value && not (key `member` value) = Alias <$> value `op` alias <* deprecated
| otherwise = Alias <$> value `op` key
where
deprecated = case boolVal (Proxy @deprecated) of
False -> return ()
True -> markDeprecated alias key
alias = Key.fromString (symbolVal $ Proxy @alias)
accessFieldWith :: forall sel a p. Selector sel => (Object -> Key -> Parser a) -> Options -> Value -> Parser (RecordField sel a p)
accessFieldWith op Options{..} v = M1 . K1 <$> withObject (`op` Key.fromString label) v
where
label = optionsRecordSelectorModifier $ selName (undefined :: RecordField sel a p)
newtype Alias (deprecated :: Bool) (alias :: Symbol) a = Alias a
deriving (Show, Eq, Semigroup, Monoid, Functor)
unAlias :: Alias deprecated alias a -> a
unAlias (Alias a) = a
class KnownBool (a :: Bool) where
boolVal :: Proxy a -> Bool
instance KnownBool 'True where
boolVal _ = True
instance KnownBool 'False where
boolVal _ = False