{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE TemplateHaskell #-}
module Data.Aeson.Schema.TH.Enum
( genFromJSONEnum
, genToJSONEnum
, mkEnum
) where
import Control.Monad (forM, unless)
import Data.Aeson (FromJSON(..), ToJSON(..), Value(..))
import Data.Char (toLower)
import Data.Maybe (mapMaybe)
import qualified Data.Text as Text
import Language.Haskell.TH
import Language.Haskell.TH.Syntax (lift)
mkEnum :: String -> [String] -> Q [Dec]
mkEnum :: String -> [String] -> Q [Dec]
mkEnum String
name [String]
vals = [[Dec]] -> [Dec]
forall (t :: * -> *) a. Foldable t => t [a] -> [a]
concat ([[Dec]] -> [Dec]) -> Q [[Dec]] -> Q [Dec]
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> [Q [Dec]] -> Q [[Dec]]
forall (t :: * -> *) (m :: * -> *) a.
(Traversable t, Monad m) =>
t (m a) -> m (t a)
sequence
[ (Dec -> [Dec] -> [Dec]
forall a. a -> [a] -> [a]
:[]) (Dec -> [Dec]) -> Q Dec -> Q [Dec]
forall (f :: * -> *) a b. Functor f => (a -> b) -> f a -> f b
<$> Q Dec
dataDec
, Name -> [Name] -> Q [Dec]
mkFromJSON Name
name' [Name]
vals'
, Name -> [Name] -> Q [Dec]
mkToJSON Name
name' [Name]
vals'
]
where
name' :: Name
name' = String -> Name
mkName String
name
vals' :: [Name]
vals' = (String -> Name) -> [String] -> [Name]
forall a b. (a -> b) -> [a] -> [b]
map String -> Name
mkName [String]
vals
dataDec :: Q Dec
dataDec = CxtQ
-> Name
-> [TyVarBndr]
-> Maybe Kind
-> [ConQ]
-> [DerivClauseQ]
-> Q Dec
dataD ([Kind] -> CxtQ
forall (f :: * -> *) a. Applicative f => a -> f a
pure []) Name
name' [] Maybe Kind
forall a. Maybe a
Nothing ((Name -> ConQ) -> [Name] -> [ConQ]
forall a b. (a -> b) -> [a] -> [b]
map Name -> ConQ
toCon [Name]
vals') [Maybe DerivStrategy -> [PredQ] -> DerivClauseQ
derivClause Maybe DerivStrategy
forall a. Maybe a
Nothing [PredQ]
deriveClasses]
deriveClasses :: [PredQ]
deriveClasses =
[ [t| Eq |]
, [t| Ord |]
, [t| Show |]
, [t| Enum |]
]
toCon :: Name -> ConQ
toCon Name
val = Name -> [BangTypeQ] -> ConQ
normalC Name
val []
genFromJSONEnum :: Name -> Q [Dec]
genFromJSONEnum :: Name -> Q [Dec]
genFromJSONEnum Name
name = Name -> Q [Name]
getEnumConstructors Name
name Q [Name] -> ([Name] -> Q [Dec]) -> Q [Dec]
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= Name -> [Name] -> Q [Dec]
mkFromJSON Name
name
genToJSONEnum :: Name -> Q [Dec]
genToJSONEnum :: Name -> Q [Dec]
genToJSONEnum Name
name = Name -> Q [Name]
getEnumConstructors Name
name Q [Name] -> ([Name] -> Q [Dec]) -> Q [Dec]
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= Name -> [Name] -> Q [Dec]
mkToJSON Name
name
getEnumConstructors :: Name -> Q [Name]
getEnumConstructors :: Name -> Q [Name]
getEnumConstructors Name
name = do
ClassI Dec
_ [Dec]
instances <- Name -> Q Info
reify ''Enum
let instanceNames :: [Name]
instanceNames = ((Dec -> Maybe Name) -> [Dec] -> [Name])
-> [Dec] -> (Dec -> Maybe Name) -> [Name]
forall a b c. (a -> b -> c) -> b -> a -> c
flip (Dec -> Maybe Name) -> [Dec] -> [Name]
forall a b. (a -> Maybe b) -> [a] -> [b]
mapMaybe [Dec]
instances ((Dec -> Maybe Name) -> [Name]) -> (Dec -> Maybe Name) -> [Name]
forall a b. (a -> b) -> a -> b
$ \case
InstanceD Maybe Overlap
_ [Kind]
_ (AppT Kind
_ (ConT Name
n)) [Dec]
_ -> Name -> Maybe Name
forall a. a -> Maybe a
Just Name
n
Dec
_ -> Maybe Name
forall a. Maybe a
Nothing
Bool -> Q () -> Q ()
forall (f :: * -> *). Applicative f => Bool -> f () -> f ()
unless (Name
name Name -> [Name] -> Bool
forall (t :: * -> *) a. (Foldable t, Eq a) => a -> t a -> Bool
`elem` [Name]
instanceNames) (Q () -> Q ()) -> Q () -> Q ()
forall a b. (a -> b) -> a -> b
$ String -> Q ()
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String -> Q ()) -> String -> Q ()
forall a b. (a -> b) -> a -> b
$ String
"Not an Enum type: " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Name -> String
forall a. Show a => a -> String
show Name
name
Name -> Q Info
reify Name
name Q Info -> (Info -> Q [Name]) -> Q [Name]
forall (m :: * -> *) a b. Monad m => m a -> (a -> m b) -> m b
>>= \case
TyConI (DataD [Kind]
_ Name
_ [TyVarBndr]
_ Maybe Kind
_ [Con]
cons [DerivClause]
_) -> [Con] -> (Con -> Q Name) -> Q [Name]
forall (t :: * -> *) (m :: * -> *) a b.
(Traversable t, Monad m) =>
t a -> (a -> m b) -> m (t b)
forM [Con]
cons ((Con -> Q Name) -> Q [Name]) -> (Con -> Q Name) -> Q [Name]
forall a b. (a -> b) -> a -> b
$ \case
NormalC Name
con [] -> Name -> Q Name
forall (m :: * -> *) a. Monad m => a -> m a
return Name
con
Con
con -> String -> Q Name
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String -> Q Name) -> String -> Q Name
forall a b. (a -> b) -> a -> b
$ String
"Invalid constructor: " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Con -> String
forall a. Show a => a -> String
show Con
con
Info
info -> String -> Q [Name]
forall (m :: * -> *) a. MonadFail m => String -> m a
fail (String -> Q [Name]) -> String -> Q [Name]
forall a b. (a -> b) -> a -> b
$ String
"Invalid data type: " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Info -> String
forall a. Show a => a -> String
show Info
info
mkFromJSON :: Name -> [Name] -> Q [Dec]
mkFromJSON :: Name -> [Name] -> Q [Dec]
mkFromJSON Name
name [Name]
cons = do
let toPattern :: Name -> PatQ
toPattern = Lit -> PatQ
litP (Lit -> PatQ) -> (Name -> Lit) -> Name -> PatQ
forall b c a. (b -> c) -> (a -> b) -> a -> c
. String -> Lit
stringL (String -> Lit) -> (Name -> String) -> Name -> Lit
forall b c a. (b -> c) -> (a -> b) -> a -> c
. (Char -> Char) -> String -> String
forall a b. (a -> b) -> [a] -> [b]
map Char -> Char
toLower (String -> String) -> (Name -> String) -> Name -> String
forall b c a. (b -> c) -> (a -> b) -> a -> c
. Name -> String
nameBase
toMatch :: Name -> MatchQ
toMatch Name
con = PatQ -> BodyQ -> [Q Dec] -> MatchQ
match (Name -> PatQ
toPattern Name
con) (ExpQ -> BodyQ
normalB [| pure $(conE con) |]) []
Name
t <- String -> Q Name
newName String
"t"
let parseEnum :: ExpQ
parseEnum = ExpQ -> [MatchQ] -> ExpQ
caseE [| Text.unpack $ Text.toLower $(varE t) |] ([MatchQ] -> ExpQ) -> [MatchQ] -> ExpQ
forall a b. (a -> b) -> a -> b
$
(Name -> MatchQ) -> [Name] -> [MatchQ]
forall a b. (a -> b) -> [a] -> [b]
map Name -> MatchQ
toMatch [Name]
cons [MatchQ] -> [MatchQ] -> [MatchQ]
forall a. [a] -> [a] -> [a]
++ [PatQ -> BodyQ -> [Q Dec] -> MatchQ
match PatQ
wildP (ExpQ -> BodyQ
normalB (ExpQ -> BodyQ) -> ExpQ -> BodyQ
forall a b. (a -> b) -> a -> b
$ ExpQ -> ExpQ -> ExpQ
appE ExpQ
badParse (ExpQ -> ExpQ) -> ExpQ -> ExpQ
forall a b. (a -> b) -> a -> b
$ Name -> ExpQ
varE Name
t) []]
[d|
instance FromJSON $(conT name) where
parseJSON (String $(varP t)) = $parseEnum
parseJSON v = $badParse v
|]
where
badParse :: ExpQ
badParse =
let prefix :: ExpQ
prefix = Lit -> ExpQ
litE (Lit -> ExpQ) -> Lit -> ExpQ
forall a b. (a -> b) -> a -> b
$ String -> Lit
stringL (String -> Lit) -> String -> Lit
forall a b. (a -> b) -> a -> b
$ String
"Bad " String -> String -> String
forall a. [a] -> [a] -> [a]
++ Name -> String
nameBase Name
name String -> String -> String
forall a. [a] -> [a] -> [a]
++ String
": "
in [| fail . ($prefix ++) . show |]
mkToJSON :: Name -> [Name] -> Q [Dec]
mkToJSON :: Name -> [Name] -> Q [Dec]
mkToJSON Name
name [Name]
cons =
[d|
instance ToJSON $(conT name) where
toJSON = $(lamCaseE $ map encodeConstructor cons)
|]
where
encodeConstructor :: Name -> MatchQ
encodeConstructor Name
con = PatQ -> BodyQ -> [Q Dec] -> MatchQ
match (Name -> [PatQ] -> PatQ
conP Name
con []) (ExpQ -> BodyQ
normalB [| String $ Text.pack $(lift $ nameBase con) |]) []