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{-# LANGUAGE DerivingStrategies #-}
{-# LANGUAGE QuantifiedConstraints #-}
{-# LANGUAGE ImpredicativeTypes #-}
{-# LANGUAGE TypeFamilies #-}
{-# LANGUAGE AllowAmbiguousTypes #-}
{-# LANGUAGE StrictData #-}
{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE DefaultSignatures #-}
module Conftrack.Value (key, Value(..), ConfigError(..), Key(..), ConfigValue(..), Origin(..), KeyPart, prefixedWith) where
import Data.Text(Text)
import qualified Data.Text as T
import qualified Data.ByteString as BS
import qualified Data.ByteString.Lazy as LB
import Data.List.NonEmpty (NonEmpty, prependList)
import qualified Data.List.NonEmpty as NonEmpty
import System.OsPath (OsPath, encodeUtf)
import qualified Data.Text.Encoding as BS
import Language.Haskell.TH.Quote (QuasiQuoter(..))
import Language.Haskell.TH.Syntax (Lift(lift))
data Value =
ConfigString BS.ByteString
| ConfigInteger Integer
| ConfigMaybeInteger BS.ByteString Integer
| ConfigOther Text Text
| ConfigBool Bool
| ConfigNull
deriving Show
type KeyPart = Text
newtype Key = Key (NonEmpty KeyPart)
deriving newtype (Eq, Ord)
deriving (Lift)
instance Show Key where
show (Key parts) = T.unpack (T.intercalate "." (NonEmpty.toList parts))
key :: QuasiQuoter
key = QuasiQuoter
{ quoteExp = lift . Key . NonEmpty.fromList . T.splitOn "." . T.pack
, quotePat = \_ -> fail "key quoter cannot be used in patterns"
, quoteType = \_ -> fail "key quasi-quote cannot be used for types"
, quoteDec = \_ -> fail "key quasi-quote cannot be used in declarations"}
prefixedWith :: Key -> [KeyPart] -> Key
prefixedWith (Key key) prefix = Key (prependList prefix key)
data ConfigError =
ParseError Text
| TypeMismatch Text Value
| NotPresent Key
| Shadowed
deriving Show
class ConfigValue a where
fromConfig :: Value -> Either ConfigError a
prettyValue :: a -> Text
default prettyValue :: Show a => a -> Text
prettyValue = T.pack . show
data Origin = forall a. ConfigValue a => Origin a Text
instance Show Origin where
show (Origin a text) = "Origin " <> T.unpack (prettyValue a) <> " " <> T.unpack text
withString :: (BS.ByteString -> Either ConfigError a) -> Value -> Either ConfigError a
withString f (ConfigString a) = f a
withString f (ConfigMaybeInteger a _) = f a
withString _ val = Left (TypeMismatch "text" val)
withInteger :: (Integer -> Either ConfigError a) -> Value -> Either ConfigError a
withInteger f (ConfigInteger a) = f a
withInteger f (ConfigMaybeInteger _ a) = f a
withInteger _ val = Left (TypeMismatch "integer" val)
instance ConfigValue Text where
fromConfig = withString (Right . BS.decodeUtf8)
instance ConfigValue Integer where
fromConfig = withInteger Right
instance ConfigValue Int where
fromConfig = withInteger (Right . fromInteger)
instance ConfigValue Bool where
fromConfig (ConfigBool b) = Right b
fromConfig val = Left (TypeMismatch "bool" val)
instance ConfigValue a => ConfigValue (Maybe a) where
fromConfig ConfigNull = Right Nothing
fromConfig just = fmap Just (fromConfig just)
prettyValue Nothing = "null"
prettyValue (Just a) = prettyValue a
instance ConfigValue OsPath where
fromConfig = \case
(ConfigString text) -> stringToPath text
(ConfigMaybeInteger text _) -> stringToPath text
val -> Left (TypeMismatch "path" val)
where stringToPath text = case encodeUtf (T.unpack (BS.decodeUtf8 text)) of
Right path -> Right path
Left err -> Left (ParseError (T.pack $ show err))
instance ConfigValue LB.ByteString where
fromConfig = withString (Right . LB.fromStrict)
instance ConfigValue BS.ByteString where
fromConfig = withString Right
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