{-# LANGUAGE CPP #-}
{-# LANGUAGE DeriveDataTypeable #-}
{-# LANGUAGE DeriveGeneric #-}
{-# LANGUAGE GeneralizedNewtypeDeriving #-}
{-# LANGUAGE Rank2Types #-}
#if __GLASGOW_HASKELL__ >= 800
-- a) THQ works on cross-compilers and unregisterised GHCs
-- b) may make compilation faster as no dynamic loading is ever needed (not sure about this)
-- c) removes one hindrance to have code inferred as SafeHaskell safe
{-# LANGUAGE TemplateHaskellQuotes #-}
#else
{-# LANGUAGE TemplateHaskell #-}
#endif
-- |
-- Module: Data.Aeson.Types.Internal
-- Copyright: (c) 2011-2016 Bryan O'Sullivan
-- (c) 2011 MailRank, Inc.
-- License: BSD3
-- Maintainer: Bryan O'Sullivan <bos@serpentine.com>
-- Stability: experimental
-- Portability: portable
--
-- Types for working with JSON data.
module Data.Aeson.Types.Internal
(
-- * Core JSON types
Value(..)
, Array
, emptyArray, isEmptyArray
, Pair
, Object
, emptyObject
-- * Type conversion
, Parser
, Result(..)
, IResult(..)
, JSONPathElement(..)
, JSONPath
, iparse
, parse
, parseEither
, parseMaybe
, modifyFailure
, parserThrowError
, parserCatchError
, formatError
, (<?>)
-- * Constructors and accessors
, object
-- * Generic and TH encoding configuration
, Options(
fieldLabelModifier
, constructorTagModifier
, allNullaryToStringTag
, omitNothingFields
, sumEncoding
, unwrapUnaryRecords
, tagSingleConstructors
)
, SumEncoding(..)
, defaultOptions
, defaultTaggedObject
-- * Used for changing CamelCase names into something else.
, camelTo
, camelTo2
-- * Other types
, DotNetTime(..)
) where
import Prelude ()
import Prelude.Compat
import Control.Applicative (Alternative(..))
import Control.Arrow (first)
import Control.DeepSeq (NFData(..))
import Control.Monad (MonadPlus(..), ap)
import Data.Char (isLower, isUpper, toLower, isAlpha, isAlphaNum)
import Data.Data (Data)
import Data.Foldable (foldl')
import Data.HashMap.Strict (HashMap)
import Data.Hashable (Hashable(..))
import Data.List (intercalate)
import Data.Scientific (Scientific)
import Data.Semigroup (Semigroup((<>)))
import Data.String (IsString(..))
import Data.Text (Text, pack, unpack)
import Data.Time (UTCTime)
import Data.Time.Format (FormatTime)
import Data.Typeable (Typeable)
import Data.Vector (Vector)
import GHC.Generics (Generic)
import qualified Control.Monad.Fail as Fail
import qualified Data.HashMap.Strict as H
import qualified Data.Scientific as S
import qualified Data.Vector as V
import qualified Language.Haskell.TH.Syntax as TH
#if !MIN_VERSION_unordered_containers(0,2,6)
import Data.List (sort)
#endif
-- | Elements of a JSON path used to describe the location of an
-- error.
data JSONPathElement = Key Text
-- ^ JSON path element of a key into an object,
-- \"object.key\".
| Index {-# UNPACK #-} !Int
-- ^ JSON path element of an index into an
-- array, \"array[index]\".
deriving (Eq, Show, Typeable)
type JSONPath = [JSONPathElement]
-- | The internal result of running a 'Parser'.
data IResult a = IError JSONPath String
| ISuccess a
deriving (Eq, Show, Typeable)
-- | The result of running a 'Parser'.
data Result a = Error String
| Success a
deriving (Eq, Show, Typeable)
instance NFData JSONPathElement where
rnf (Key t) = rnf t
rnf (Index i) = rnf i
instance (NFData a) => NFData (IResult a) where
rnf (ISuccess a) = rnf a
rnf (IError path err) = rnf path `seq` rnf err
instance (NFData a) => NFData (Result a) where
rnf (Success a) = rnf a
rnf (Error err) = rnf err
instance Functor IResult where
fmap f (ISuccess a) = ISuccess (f a)
fmap _ (IError path err) = IError path err
{-# INLINE fmap #-}
instance Functor Result where
fmap f (Success a) = Success (f a)
fmap _ (Error err) = Error err
{-# INLINE fmap #-}
instance Monad IResult where
return = pure
{-# INLINE return #-}
ISuccess a >>= k = k a
IError path err >>= _ = IError path err
{-# INLINE (>>=) #-}
fail = Fail.fail
{-# INLINE fail #-}
instance Fail.MonadFail IResult where
fail err = IError [] err
{-# INLINE fail #-}
instance Monad Result where
return = pure
{-# INLINE return #-}
Success a >>= k = k a
Error err >>= _ = Error err
{-# INLINE (>>=) #-}
fail = Fail.fail
{-# INLINE fail #-}
instance Fail.MonadFail Result where
fail err = Error err
{-# INLINE fail #-}
instance Applicative IResult where
pure = ISuccess
{-# INLINE pure #-}
(<*>) = ap
{-# INLINE (<*>) #-}
instance Applicative Result where
pure = Success
{-# INLINE pure #-}
(<*>) = ap
{-# INLINE (<*>) #-}
instance MonadPlus IResult where
mzero = fail "mzero"
{-# INLINE mzero #-}
mplus a@(ISuccess _) _ = a
mplus _ b = b
{-# INLINE mplus #-}
instance MonadPlus Result where
mzero = fail "mzero"
{-# INLINE mzero #-}
mplus a@(Success _) _ = a
mplus _ b = b
{-# INLINE mplus #-}
instance Alternative IResult where
empty = mzero
{-# INLINE empty #-}
(<|>) = mplus
{-# INLINE (<|>) #-}
instance Alternative Result where
empty = mzero
{-# INLINE empty #-}
(<|>) = mplus
{-# INLINE (<|>) #-}
instance Semigroup (IResult a) where
(<>) = mplus
{-# INLINE (<>) #-}
instance Monoid (IResult a) where
mempty = fail "mempty"
{-# INLINE mempty #-}
mappend = (<>)
{-# INLINE mappend #-}
instance Semigroup (Result a) where
(<>) = mplus
{-# INLINE (<>) #-}
instance Monoid (Result a) where
mempty = fail "mempty"
{-# INLINE mempty #-}
mappend = (<>)
{-# INLINE mappend #-}
instance Foldable IResult where
foldMap _ (IError _ _) = mempty
foldMap f (ISuccess y) = f y
{-# INLINE foldMap #-}
foldr _ z (IError _ _) = z
foldr f z (ISuccess y) = f y z
{-# INLINE foldr #-}
instance Foldable Result where
foldMap _ (Error _) = mempty
foldMap f (Success y) = f y
{-# INLINE foldMap #-}
foldr _ z (Error _) = z
foldr f z (Success y) = f y z
{-# INLINE foldr #-}
instance Traversable IResult where
traverse _ (IError path err) = pure (IError path err)
traverse f (ISuccess a) = ISuccess <$> f a
{-# INLINE traverse #-}
instance Traversable Result where
traverse _ (Error err) = pure (Error err)
traverse f (Success a) = Success <$> f a
{-# INLINE traverse #-}
-- | Failure continuation.
type Failure f r = JSONPath -> String -> f r
-- | Success continuation.
type Success a f r = a -> f r
-- | A JSON parser.
newtype Parser a = Parser {
runParser :: forall f r.
JSONPath
-> Failure f r
-> Success a f r
-> f r
}
instance Monad Parser where
m >>= g = Parser $ \path kf ks -> let ks' a = runParser (g a) path kf ks
in runParser m path kf ks'
{-# INLINE (>>=) #-}
return = pure
{-# INLINE return #-}
fail = Fail.fail
{-# INLINE fail #-}
instance Fail.MonadFail Parser where
fail msg = Parser $ \path kf _ks -> kf (reverse path) msg
{-# INLINE fail #-}
instance Functor Parser where
fmap f m = Parser $ \path kf ks -> let ks' a = ks (f a)
in runParser m path kf ks'
{-# INLINE fmap #-}
instance Applicative Parser where
pure a = Parser $ \_path _kf ks -> ks a
{-# INLINE pure #-}
(<*>) = apP
{-# INLINE (<*>) #-}
instance Alternative Parser where
empty = fail "empty"
{-# INLINE empty #-}
(<|>) = mplus
{-# INLINE (<|>) #-}
instance MonadPlus Parser where
mzero = fail "mzero"
{-# INLINE mzero #-}
mplus a b = Parser $ \path kf ks -> let kf' _ _ = runParser b path kf ks
in runParser a path kf' ks
{-# INLINE mplus #-}
instance Semigroup (Parser a) where
(<>) = mplus
{-# INLINE (<>) #-}
instance Monoid (Parser a) where
mempty = fail "mempty"
{-# INLINE mempty #-}
mappend = (<>)
{-# INLINE mappend #-}
apP :: Parser (a -> b) -> Parser a -> Parser b
apP d e = do
b <- d
a <- e
return (b a)
{-# INLINE apP #-}
-- | A JSON \"object\" (key\/value map).
type Object = HashMap Text Value
-- | A JSON \"array\" (sequence).
type Array = Vector Value
-- | A JSON value represented as a Haskell value.
data Value = Object !Object
| Array !Array
| String !Text
| Number !Scientific
| Bool !Bool
| Null
deriving (Eq, Read, Show, Typeable, Data, Generic)
-- | A newtype wrapper for 'UTCTime' that uses the same non-standard
-- serialization format as Microsoft .NET, whose
-- <https://msdn.microsoft.com/en-us/library/system.datetime(v=vs.110).aspx System.DateTime>
-- type is by default serialized to JSON as in the following example:
--
-- > /Date(1302547608878)/
--
-- The number represents milliseconds since the Unix epoch.
newtype DotNetTime = DotNetTime {
fromDotNetTime :: UTCTime
-- ^ Acquire the underlying value.
} deriving (Eq, Ord, Read, Show, Typeable, FormatTime)
instance NFData Value where
rnf (Object o) = rnf o
rnf (Array a) = foldl' (\x y -> rnf y `seq` x) () a
rnf (String s) = rnf s
rnf (Number n) = rnf n
rnf (Bool b) = rnf b
rnf Null = ()
instance IsString Value where
fromString = String . pack
{-# INLINE fromString #-}
hashValue :: Int -> Value -> Int
#if MIN_VERSION_unordered_containers(0,2,6)
hashValue s (Object o) = s `hashWithSalt` (0::Int) `hashWithSalt` o
#else
hashValue s (Object o) = foldl' hashWithSalt
(s `hashWithSalt` (0::Int)) assocHashesSorted
where
assocHashesSorted = sort [hash k `hashWithSalt` v | (k, v) <- H.toList o]
#endif
hashValue s (Array a) = foldl' hashWithSalt
(s `hashWithSalt` (1::Int)) a
hashValue s (String str) = s `hashWithSalt` (2::Int) `hashWithSalt` str
hashValue s (Number n) = s `hashWithSalt` (3::Int) `hashWithSalt` n
hashValue s (Bool b) = s `hashWithSalt` (4::Int) `hashWithSalt` b
hashValue s Null = s `hashWithSalt` (5::Int)
instance Hashable Value where
hashWithSalt = hashValue
-- @since 0.11.0.0
instance TH.Lift Value where
lift Null = [| Null |]
lift (Bool b) = [| Bool b |]
lift (Number n) = [| Number (S.scientific c e) |]
where
c = S.coefficient n
e = S.base10Exponent n
lift (String t) = [| String (pack s) |]
where s = unpack t
lift (Array a) = [| Array (V.fromList a') |]
where a' = V.toList a
lift (Object o) = [| Object (H.fromList . map (first pack) $ o') |]
where o' = map (first unpack) . H.toList $ o
-- | The empty array.
emptyArray :: Value
emptyArray = Array V.empty
-- | Determines if the 'Value' is an empty 'Array'.
-- Note that: @isEmptyArray 'emptyArray'@.
isEmptyArray :: Value -> Bool
isEmptyArray (Array arr) = V.null arr
isEmptyArray _ = False
-- | The empty object.
emptyObject :: Value
emptyObject = Object H.empty
-- | Run a 'Parser'.
parse :: (a -> Parser b) -> a -> Result b
parse m v = runParser (m v) [] (const Error) Success
{-# INLINE parse #-}
-- | Run a 'Parser'.
iparse :: (a -> Parser b) -> a -> IResult b
iparse m v = runParser (m v) [] IError ISuccess
{-# INLINE iparse #-}
-- | Run a 'Parser' with a 'Maybe' result type.
parseMaybe :: (a -> Parser b) -> a -> Maybe b
parseMaybe m v = runParser (m v) [] (\_ _ -> Nothing) Just
{-# INLINE parseMaybe #-}
-- | Run a 'Parser' with an 'Either' result type. If the parse fails,
-- the 'Left' payload will contain an error message.
parseEither :: (a -> Parser b) -> a -> Either String b
parseEither m v = runParser (m v) [] onError Right
where onError path msg = Left (formatError path msg)
{-# INLINE parseEither #-}
-- | Annotate an error message with a
-- <http://goessner.net/articles/JsonPath/ JSONPath> error location.
formatError :: JSONPath -> String -> String
formatError path msg = "Error in " ++ format "$" path ++ ": " ++ msg
where
format :: String -> JSONPath -> String
format pfx [] = pfx
format pfx (Index idx:parts) = format (pfx ++ "[" ++ show idx ++ "]") parts
format pfx (Key key:parts) = format (pfx ++ formatKey key) parts
formatKey :: Text -> String
formatKey key
| isIdentifierKey strKey = "." ++ strKey
| otherwise = "['" ++ escapeKey strKey ++ "']"
where strKey = unpack key
isIdentifierKey :: String -> Bool
isIdentifierKey [] = False
isIdentifierKey (x:xs) = isAlpha x && all isAlphaNum xs
escapeKey :: String -> String
escapeKey = concatMap escapeChar
escapeChar :: Char -> String
escapeChar '\'' = "\\'"
escapeChar '\\' = "\\\\"
escapeChar c = [c]
-- | A key\/value pair for an 'Object'.
type Pair = (Text, Value)
-- | Create a 'Value' from a list of name\/value 'Pair's. If duplicate
-- keys arise, earlier keys and their associated values win.
object :: [Pair] -> Value
object = Object . H.fromList
{-# INLINE object #-}
-- | Add JSON Path context to a parser
--
-- When parsing a complex structure, it helps to annotate (sub)parsers
-- with context, so that if an error occurs, you can find its location.
--
-- > withObject "Person" $ \o ->
-- > Person
-- > <$> o .: "name" <?> Key "name"
-- > <*> o .: "age" <?> Key "age"
--
-- (Standard methods like '(.:)' already do this.)
--
-- With such annotations, if an error occurs, you will get a JSON Path
-- location of that error.
--
-- Since 0.10
(<?>) :: Parser a -> JSONPathElement -> Parser a
p <?> pathElem = Parser $ \path kf ks -> runParser p (pathElem:path) kf ks
-- | If the inner @Parser@ failed, modify the failure message using the
-- provided function. This allows you to create more descriptive error messages.
-- For example:
--
-- > parseJSON (Object o) = modifyFailure
-- > ("Parsing of the Foo value failed: " ++)
-- > (Foo <$> o .: "someField")
--
-- Since 0.6.2.0
modifyFailure :: (String -> String) -> Parser a -> Parser a
modifyFailure f (Parser p) = Parser $ \path kf ks ->
p path (\p' m -> kf p' (f m)) ks
-- | Throw a parser error with an additional path.
--
-- @since 1.2.1.0
parserThrowError :: JSONPath -> String -> Parser a
parserThrowError path' msg = Parser $ \path kf _ks ->
kf (reverse path ++ path') msg
-- | A handler function to handle previous errors and return to normal execution.
--
-- @since 1.2.1.0
parserCatchError :: Parser a -> (JSONPath -> String -> Parser a) -> Parser a
parserCatchError (Parser p) handler = Parser $ \path kf ks ->
p path (\e msg -> runParser (handler e msg) path kf ks) ks
--------------------------------------------------------------------------------
-- Generic and TH encoding configuration
--------------------------------------------------------------------------------
-- | Options that specify how to encode\/decode your datatype to\/from JSON.
--
-- Options can be set using record syntax on 'defaultOptions' with the fields
-- below.
data Options = Options
{ fieldLabelModifier :: String -> String
-- ^ Function applied to field labels.
-- Handy for removing common record prefixes for example.
, constructorTagModifier :: String -> String
-- ^ Function applied to constructor tags which could be handy
-- for lower-casing them for example.
, allNullaryToStringTag :: Bool
-- ^ If 'True' the constructors of a datatype, with /all/
-- nullary constructors, will be encoded to just a string with
-- the constructor tag. If 'False' the encoding will always
-- follow the `sumEncoding`.
, omitNothingFields :: Bool
-- ^ If 'True' record fields with a 'Nothing' value will be
-- omitted from the resulting object. If 'False' the resulting
-- object will include those fields mapping to @null@.
, sumEncoding :: SumEncoding
-- ^ Specifies how to encode constructors of a sum datatype.
, unwrapUnaryRecords :: Bool
-- ^ Hide the field name when a record constructor has only one
-- field, like a newtype.
, tagSingleConstructors :: Bool
-- ^ Encode types with a single constructor as sums,
-- so that `allNullaryToStringTag` and `sumEncoding` apply.
}
instance Show Options where
show (Options f c a o s u t) =
"Options {"
++ intercalate ", "
[ "fieldLabelModifier =~ " ++ show (f "exampleField")
, "constructorTagModifier =~ " ++ show (c "ExampleConstructor")
, "allNullaryToStringTag = " ++ show a
, "omitNothingFields = " ++ show o
, "sumEncoding = " ++ show s
, "unwrapUnaryRecords = " ++ show u
, "tagSingleConstructors = " ++ show t
]
++ "}"
-- | Specifies how to encode constructors of a sum datatype.
data SumEncoding =
TaggedObject { tagFieldName :: String
, contentsFieldName :: String
}
-- ^ A constructor will be encoded to an object with a field
-- 'tagFieldName' which specifies the constructor tag (modified by
-- the 'constructorTagModifier'). If the constructor is a record
-- the encoded record fields will be unpacked into this object. So
-- make sure that your record doesn't have a field with the same
-- label as the 'tagFieldName'. Otherwise the tag gets overwritten
-- by the encoded value of that field! If the constructor is not a
-- record the encoded constructor contents will be stored under
-- the 'contentsFieldName' field.
| UntaggedValue
-- ^ Constructor names won't be encoded. Instead only the contents of the
-- constructor will be encoded as if the type had a single constructor. JSON
-- encodings have to be disjoint for decoding to work properly.
--
-- When decoding, constructors are tried in the order of definition. If some
-- encodings overlap, the first one defined will succeed.
--
-- /Note:/ Nullary constructors are encoded as strings (using
-- 'constructorTagModifier'). Having a nullary constructor alongside a
-- single field constructor that encodes to a string leads to ambiguity.
--
-- /Note:/ Only the last error is kept when decoding, so in the case of
-- malformed JSON, only an error for the last constructor will be reported.
| ObjectWithSingleField
-- ^ A constructor will be encoded to an object with a single
-- field named after the constructor tag (modified by the
-- 'constructorTagModifier') which maps to the encoded contents of
-- the constructor.
| TwoElemArray
-- ^ A constructor will be encoded to a 2-element array where the
-- first element is the tag of the constructor (modified by the
-- 'constructorTagModifier') and the second element the encoded
-- contents of the constructor.
deriving (Eq, Show)
-- | Default encoding 'Options':
--
-- @
-- 'Options'
-- { 'fieldLabelModifier' = id
-- , 'constructorTagModifier' = id
-- , 'allNullaryToStringTag' = True
-- , 'omitNothingFields' = False
-- , 'sumEncoding' = 'defaultTaggedObject'
-- , 'unwrapUnaryRecords' = False
-- , 'tagSingleConstructors' = False
-- }
-- @
defaultOptions :: Options
defaultOptions = Options
{ fieldLabelModifier = id
, constructorTagModifier = id
, allNullaryToStringTag = True
, omitNothingFields = False
, sumEncoding = defaultTaggedObject
, unwrapUnaryRecords = False
, tagSingleConstructors = False
}
-- | Default 'TaggedObject' 'SumEncoding' options:
--
-- @
-- defaultTaggedObject = 'TaggedObject'
-- { 'tagFieldName' = \"tag\"
-- , 'contentsFieldName' = \"contents\"
-- }
-- @
defaultTaggedObject :: SumEncoding
defaultTaggedObject = TaggedObject
{ tagFieldName = "tag"
, contentsFieldName = "contents"
}
-- | Converts from CamelCase to another lower case, interspersing
-- the character between all capital letters and their previous
-- entries, except those capital letters that appear together,
-- like 'API'.
--
-- For use by Aeson template haskell calls.
--
-- > camelTo '_' 'CamelCaseAPI' == "camel_case_api"
camelTo :: Char -> String -> String
{-# DEPRECATED camelTo "Use camelTo2 for better results" #-}
camelTo c = lastWasCap True
where
lastWasCap :: Bool -- ^ Previous was a capital letter
-> String -- ^ The remaining string
-> String
lastWasCap _ [] = []
lastWasCap prev (x : xs) = if isUpper x
then if prev
then toLower x : lastWasCap True xs
else c : toLower x : lastWasCap True xs
else x : lastWasCap False xs
-- | Better version of 'camelTo'. Example where it works better:
--
-- > camelTo '_' 'CamelAPICase' == "camel_apicase"
-- > camelTo2 '_' 'CamelAPICase' == "camel_api_case"
camelTo2 :: Char -> String -> String
camelTo2 c = map toLower . go2 . go1
where go1 "" = ""
go1 (x:u:l:xs) | isUpper u && isLower l = x : c : u : l : go1 xs
go1 (x:xs) = x : go1 xs
go2 "" = ""
go2 (l:u:xs) | isLower l && isUpper u = l : c : u : go2 xs
go2 (x:xs) = x : go2 xs