@@ -5,20 +5,16 @@
55{-# LANGUAGE FlexibleInstances #-}
66{-# LANGUAGE GADTs #-}
77{-# LANGUAGE MultiParamTypeClasses #-}
8−{-# LANGUAGE NamedFieldPuns #-}
98{-# LANGUAGE NoImplicitPrelude #-}
109{-# LANGUAGE OverloadedStrings #-}
10+{-# LANGUAGE PolyKinds #-}
1111{-# LANGUAGE RecordWildCards #-}
1212{-# LANGUAGE ScopedTypeVariables #-}
1313{-# LANGUAGE TypeOperators #-}
14−{-# LANGUAGE TypeSynonymInstances #-}
14+{-# LANGUAGE TupleSections #-}
1515{-# LANGUAGE UndecidableInstances #-}
1616{-# LANGUAGE ViewPatterns #-}
1717
18−#if __GLASGOW_HASKELL__ >= 706
19−{-# LANGUAGE PolyKinds #-}
20−#endif
21−
2218#include "incoherent-compat.h"
2319#include "overlapping-compat.h"
2420
@@ -46,6 +42,9 @@ module Data.Aeson.Types.FromJSON
4642 , coerceFromJSONKeyFunction
4743 , mapFromJSONKeyFunction
4844
45+ , GFromJSONKey()
46+ , genericFromJSONKey
47+
4948 -- * List functions
5049 , listParser
5150
@@ -61,6 +60,7 @@ module Data.Aeson.Types.FromJSON
6160 , fromJSON
6261 , ifromJSON
6362 , typeMismatch
63+ , unexpected
6464 , parseField
6565 , parseFieldMaybe
6666 , parseFieldMaybe'
@@ -80,14 +80,14 @@ module Data.Aeson.Types.FromJSON
8080
8181import Prelude.Compat
8282
83−import Control.Applicative ((<|>), Const(..))
84−import Control.Monad ((<=<), zipWithM)
83+import Control.Applicative ((<|>), Const(..), liftA2)
84+import Control.Monad (zipWithM)
8585import Data.Aeson.Internal.Functions (mapKey)
8686import Data.Aeson.Parser.Internal (eitherDecodeWith, jsonEOF)
8787import Data.Aeson.Types.Generic
8888import Data.Aeson.Types.Internal
8989import Data.Bits (unsafeShiftR)
90−import Data.Fixed (Fixed, HasResolution)
90+import Data.Fixed (Fixed, HasResolution (resolution), Nano)
9191import Data.Functor.Compose (Compose(..))
9292import Data.Functor.Identity (Identity(..))
9393import Data.Functor.Product (Product(..))
@@ -103,8 +103,10 @@ import Data.Scientific (Scientific, base10Exponent)
103103import Data.Tagged (Tagged(..))
104104import Data.Text (Text, pack, unpack)
105105import Data.Time (Day, DiffTime, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
106−import Data.Time.Format (parseTime)
107−import Data.Time.Locale.Compat (defaultTimeLocale)
106+import Data.Time.Calendar.Compat (CalendarDiffDays (..), DayOfWeek (..))
107+import Data.Time.LocalTime.Compat (CalendarDiffTime (..))
108+import Data.Time.Clock.System.Compat (SystemTime (..))
109+import Data.Time.Format.Compat (parseTimeM, defaultTimeLocale)
108110import Data.Traversable as Tr (sequence)
109111import Data.Vector (Vector)
110112import Data.Version (Version, parseVersion)
@@ -116,9 +118,9 @@ import GHC.Generics
116118import Numeric.Natural (Natural)
117119import Text.ParserCombinators.ReadP (readP_to_S)
118120import Unsafe.Coerce (unsafeCoerce)
119−import qualified Data.Aeson.Compat as Compat
120121import qualified Data.Aeson.Parser.Time as Time
121122import qualified Data.Attoparsec.ByteString.Char8 as A (endOfInput, parseOnly, scientific)
123+import qualified Data.ByteString.Lazy as L
122124import qualified Data.DList as DList
123125import qualified Data.HashMap.Strict as H
124126import qualified Data.HashSet as HashSet
@@ -147,22 +149,14 @@ import qualified Data.Primitive.SmallArray as PM
147149import qualified Data.Primitive.Types as PM
148150
149151#if MIN_VERSION_primitive(0,6,4)
152+#if !MIN_VERSION_primitive(0,7,0)
150153import qualified Data.Primitive.UnliftedArray as PM
154+#endif
151155import qualified Data.Primitive.PrimArray as PM
152156#endif
153157
154−#ifndef HAS_COERCIBLE
155−#define HAS_COERCIBLE (__GLASGOW_HASKELL__ >= 707)
156−#endif
157158
158−#if HAS_COERCIBLE
159159import Data.Coerce (Coercible, coerce)
160−coerce' :: Coercible a b => a -> b
161−coerce' = coerce
162−#else
163−coerce' :: a -> b
164−coerce' = unsafeCoerce
165−#endif
166160
167161parseIndexedJSON :: (Value -> Parser a) -> Int -> Value -> Parser a
168162parseIndexedJSON p idx value = p value <?> Index idx
@@ -171,7 +165,7 @@ parseIndexedJSON p idx value = p value <?> Index idx
171165parseIndexedJSONPair :: (Value -> Parser a) -> (Value -> Parser b) -> Int -> Value -> Parser (a, b)
172166parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
173167 where
174− p = withArray "(k,v)" $ \ab ->
168+ p = withArray "(k, v)" $ \ab ->
175169 let n = V.length ab
176170 in if n == 2
177171 then (,) <$> parseJSONElemAtIndex keyParser 0 ab
@@ -184,33 +178,33 @@ parseJSONElemAtIndex :: (Value -> Parser a) -> Int -> V.Vector Value -> Parser a
184178parseJSONElemAtIndex p idx ary = p (V.unsafeIndex ary idx) <?> Index idx
185179
186180parseRealFloat :: RealFloat a => String -> Value -> Parser a
187−parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
188−parseRealFloat _ Null = pure (0/0)
189−parseRealFloat expected v = typeMismatch expected v
181+parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
182+parseRealFloat _ Null = pure (0/0)
183+parseRealFloat name v = prependContext name (unexpected v)
190184{-# INLINE parseRealFloat #-}
191185
192−parseIntegralFromScientific :: forall a. Integral a => String -> Scientific -> Parser a
193−parseIntegralFromScientific expected s =
186+parseIntegralFromScientific :: forall a. Integral a => Scientific -> Parser a
187+parseIntegralFromScientific s =
194188 case Scientific.floatingOrInteger s :: Either Double a of
195189 Right x -> pure x
196− Left _ -> fail $ "expected " ++ expected ++ ", encountered floating number " ++ show s
190+ Left _ -> fail $ "unexpected floating number " ++ show s
197191{-# INLINE parseIntegralFromScientific #-}
198192
199193parseIntegral :: Integral a => String -> Value -> Parser a
200−parseIntegral expected =
201− withBoundedScientific expected $ parseIntegralFromScientific expected
194+parseIntegral name =
195+ prependContext name . withBoundedScientific' parseIntegralFromScientific
202196{-# INLINE parseIntegral #-}
203197
204−parseBoundedIntegralFromScientific :: (Bounded a, Integral a) => String -> Scientific -> Parser a
205−parseBoundedIntegralFromScientific expected s = maybe
206− (fail $ expected ++ " is either floating or will cause over or underflow: " ++ show s)
198+parseBoundedIntegralFromScientific :: (Bounded a, Integral a) => Scientific -> Parser a
199+parseBoundedIntegralFromScientific s = maybe
200+ (fail $ "value is either floating or will cause over or underflow " ++ show s)
207201 pure
208202 (Scientific.toBoundedInteger s)
209203{-# INLINE parseBoundedIntegralFromScientific #-}
210204
211205parseBoundedIntegral :: (Bounded a, Integral a) => String -> Value -> Parser a
212−parseBoundedIntegral expected =
213− withScientific expected $ parseBoundedIntegralFromScientific expected
206+parseBoundedIntegral name =
207+ prependContext name . withScientific' parseBoundedIntegralFromScientific
214208{-# INLINE parseBoundedIntegral #-}
215209
216210parseScientificText :: Text -> Parser Scientific
@@ -220,18 +214,20 @@ parseScientificText
220214 . T.encodeUtf8
221215
222216parseIntegralText :: Integral a => String -> Text -> Parser a
223−parseIntegralText expected t
224− = parseScientificText t
225− >>= rejectLargeExponent
226− >>= parseIntegralFromScientific expected
217+parseIntegralText name t =
218+ prependContext name $
219+ parseScientificText t
220+ >>= rejectLargeExponent
221+ >>= parseIntegralFromScientific
227222 where
228223 rejectLargeExponent :: Scientific -> Parser Scientific
229− rejectLargeExponent s = withBoundedScientific expected pure (Number s)
224+ rejectLargeExponent s = withBoundedScientific' pure (Number s)
230225{-# INLINE parseIntegralText #-}
231226
232227parseBoundedIntegralText :: (Bounded a, Integral a) => String -> Text -> Parser a
233−parseBoundedIntegralText expected t =
234− parseScientificText t >>= parseBoundedIntegralFromScientific expected
228+parseBoundedIntegralText name t =
229+ prependContext name $
230+ parseScientificText t >>= parseBoundedIntegralFromScientific
235231
236232parseOptionalFieldWith :: (Value -> Parser (Maybe a))
237233 -> Object -> Text -> Parser (Maybe a)
@@ -291,14 +287,21 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
291287--
292288-- The basic ways to signal a failed conversion are as follows:
293289--
294−-- * 'empty' and 'mzero' work, but are terse and uninformative;
290+-- * 'fail' yields a custom error message: it is the recommended way of
291+-- reporting a failure;
295292--
296−-- * 'fail' yields a custom error message;
293+-- * 'Control.Applicative.empty' (or 'Control.Monad.mzero') is uninformative:
294+-- use it when the error is meant to be caught by some @('<|>')@;
297295--
298−-- * 'typeMismatch' produces an informative message for cases when the
299−-- value encountered is not of the expected type.
296+-- * 'typeMismatch' can be used to report a failure when the encountered value
297+-- is not of the expected JSON type; 'unexpected' is an appropriate alternative
298+-- when more than one type may be expected, or to keep the expected type
299+-- implicit.
300300--
301−-- An example type and instance using 'typeMismatch':
301+-- 'prependFailure' (or 'modifyFailure') add more information to a parser's
302+-- error messages.
303+--
304+-- An example type and instance using 'typeMismatch' and 'prependFailure':
302305--
303306-- @
304307-- \-- Allow ourselves to write 'Text' literals.
@@ -312,13 +315,15 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
312315-- '<*>' v '.:' \"y\"
313316--
314317-- \-- We do not expect a non-'Object' value here.
315−-- \-- We could use 'mzero' to fail, but 'typeMismatch'
318+-- \-- We could use 'Control.Applicative.empty' to fail, but 'typeMismatch'
316319-- \-- gives a much more informative error message.
317−-- 'parseJSON' invalid = 'typeMismatch' \"Coord\" invalid
320+-- 'parseJSON' invalid =
321+-- 'prependFailure' "parsing Coord failed, "
322+-- ('typeMismatch' \"Object\" invalid)
318323-- @
319324--
320325-- For this common case of only being concerned with a single
321−-- type of JSON value, the functions 'withObject', 'withNumber', etc.
326+-- type of JSON value, the functions 'withObject', 'withScientific', etc.
322327-- are provided. Their use is to be preferred when possible, since
323328-- they are more terse. Using 'withObject', we can rewrite the above instance
324329-- (assuming the same language extension and data type) as:
@@ -357,7 +362,7 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
357362-- @
358363--
359364-- The default implementation will be equivalent to
360−-- @parseJSON = 'genericParseJSON' 'defaultOptions'@; If you need different
365+-- @parseJSON = 'genericParseJSON' 'defaultOptions'@; if you need different
361366-- options, you can customize the generic decoding by defining:
362367--
363368-- @
@@ -375,13 +380,11 @@ class FromJSON a where
375380 parseJSON = genericParseJSON defaultOptions
376381
377382 parseJSONList :: Value -> Parser [a]
378− parseJSONList (Array a)
379− = zipWithM (parseIndexedJSON parseJSON) [0..]
383+ parseJSONList = withArray "[]" $ \a ->
384+ zipWithM (parseIndexedJSON parseJSON) [0..]
380385 . V.toList
381386 $ a
382387
383− parseJSONList v = typeMismatch "[a]" v
384−
385388-------------------------------------------------------------------------------
386389-- Classes and types for map keys
387390-------------------------------------------------------------------------------
@@ -393,6 +396,16 @@ class FromJSON a where
393396-- > newtype SomeId = SomeId { getSomeId :: Text }
394397-- > deriving (Eq,Ord,Hashable,FromJSONKey)
395398--
399+-- If you have a sum of nullary constructors, you may use the generic
400+-- implementation:
401+--
402+-- @
403+-- data Color = Red | Green | Blue
404+-- deriving Generic
405+--
406+-- instance 'FromJSONKey' Color where
407+-- 'fromJSONKey' = 'genericFromJSONKey' 'defaultJSONKeyOptions'
408+-- @
396409class FromJSONKey a where
397410 -- | Strategy for parsing the key of a map-like container.
398411 fromJSONKey :: FromJSONKeyFunction a
@@ -415,11 +428,7 @@ class FromJSONKey a where
415428-- At the moment this type is intentionally not exported. 'FromJSONKeyFunction'
416429-- can be inspected, but cannot be constructed.
417430data CoerceText a where
418−#if HAS_COERCIBLE
419431 CoerceText :: Coercible Text a => CoerceText a
420−#else
421− CoerceText :: CoerceText a
422−#endif
423432
424433-- | This type is related to 'ToJSONKeyFunction'. If 'FromJSONKeyValue' is used in the
425434-- 'FromJSONKey' instance, then 'ToJSONKeyValue' should be used in the 'ToJSONKey'
@@ -439,7 +448,7 @@ data FromJSONKeyFunction a
439448
440449-- | Only law abiding up to interpretation
441450instance Functor FromJSONKeyFunction where
442− fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce')
451+ fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce)
443452 fmap h (FromJSONKeyText f) = FromJSONKeyText (h . f)
444453 fmap h (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap h . f)
445454 fmap h (FromJSONKeyValue f) = FromJSONKeyValue (fmap h . f)
@@ -453,9 +462,7 @@ instance Functor FromJSONKeyFunction where
453462--
454463-- On pre GHC 7.8 this is unconstrainted function.
455464fromJSONKeyCoerce ::
456−#if HAS_COERCIBLE
457465 Coercible Text a =>
458−#endif
459466 FromJSONKeyFunction a
460467fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
461468
@@ -463,60 +470,91 @@ fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
463470--
464471-- See note on 'fromJSONKeyCoerce'.
465472coerceFromJSONKeyFunction ::
466−#if HAS_COERCIBLE
467473 Coercible a b =>
468−#endif
469474 FromJSONKeyFunction a -> FromJSONKeyFunction b
470−#if HAS_COERCIBLE
471475coerceFromJSONKeyFunction = coerce
472−#else
473−coerceFromJSONKeyFunction (FromJSONKeyCoerce CoerceText) = FromJSONKeyCoerce CoerceText
474−coerceFromJSONKeyFunction (FromJSONKeyText f) = FromJSONKeyText (coerce' . f)
475−coerceFromJSONKeyFunction (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap coerce' . f)
476−coerceFromJSONKeyFunction (FromJSONKeyValue f) = FromJSONKeyValue (fmap coerce' . f)
477−#endif
478476
479477{-# RULES
480478 "FromJSONKeyCoerce: fmap id" forall (x :: FromJSONKeyFunction a).
481479 fmap id x = x
482480 #-}
483−#if HAS_COERCIBLE
484481{-# RULES
485482 "FromJSONKeyCoerce: fmap coerce" forall x .
486483 fmap coerce x = coerceFromJSONKeyFunction x
487484 #-}
488−#endif
489485
490486-- | Same as 'fmap'. Provided for the consistency with 'ToJSONKeyFunction'.
491487mapFromJSONKeyFunction :: (a -> b) -> FromJSONKeyFunction a -> FromJSONKeyFunction b
492488mapFromJSONKeyFunction = fmap
493489
490+-- | 'fromJSONKey' for 'Generic' types.
491+-- These types must be sums of nullary constructors, whose names will be used
492+-- as keys for JSON objects.
493+--
494+-- See also 'genericToJSONKey'.
495+--
496+-- === __Example__
497+--
498+-- @
499+-- data Color = Red | Green | Blue
500+-- deriving 'Generic'
501+--
502+-- instance 'FromJSONKey' Color where
503+-- 'fromJSONKey' = 'genericFromJSONKey' 'defaultJSONKeyOptions'
504+-- @
505+genericFromJSONKey :: forall a. (Generic a, GFromJSONKey (Rep a))
506+ => JSONKeyOptions
507+ -> FromJSONKeyFunction a
508+genericFromJSONKey opts = FromJSONKeyTextParser $ \t ->
509+ case parseSumFromString (keyModifier opts) t of
510+ Nothing -> fail $
511+ "invalid key " ++ show t ++ ", expected one of " ++ show cnames
512+ Just k -> pure (to k)
513+ where
514+ cnames = unTagged2 (constructorTags (keyModifier opts) :: Tagged2 (Rep a) [String])
515+
516+class (ConstructorNames f, SumFromString f) => GFromJSONKey f where
517+instance (ConstructorNames f, SumFromString f) => GFromJSONKey f where
518+
494519-------------------------------------------------------------------------------
495520-- Functions needed for documentation
496521-------------------------------------------------------------------------------
497522
498523-- | Fail parsing due to a type mismatch, with a descriptive message.
499524--
500−-- Example usage:
525+-- The following wrappers should generally be prefered:
526+-- 'withObject', 'withArray', 'withText', 'withBool'.
501527--
502−-- @
503−-- instance FromJSON Coord where
504−-- parseJSON ('Object' v) = {- type matches, life is good -}
505−-- parseJSON wat = 'typeMismatch' \"Coord\" wat
506−-- @
507−typeMismatch :: String -- ^ The name of the type you are trying to parse.
528+-- ==== Error message example
529+--
530+-- > typeMismatch "Object" (String "oops")
531+-- > -- Error: "expected Object, but encountered String"
532+typeMismatch :: String -- ^ The name of the JSON type being parsed
533+ -- (@\"Object\"@, @\"Array\"@, @\"String\"@, @\"Number\"@,
534+ -- @\"Boolean\"@, or @\"Null\"@).
508535 -> Value -- ^ The actual value encountered.
509536 -> Parser a
510537typeMismatch expected actual =
511− fail $ "expected " ++ expected ++ ", encountered " ++ name
512− where
513− name = case actual of
514− Object _ -> "Object"
515− Array _ -> "Array"
516− String _ -> "String"
517− Number _ -> "Number"
518− Bool _ -> "Boolean"
519− Null -> "Null"
538+ fail $ "expected " ++ expected ++ ", but encountered " ++ typeOf actual
539+
540+-- | Fail parsing due to a type mismatch, when the expected types are implicit.
541+--
542+-- ==== Error message example
543+--
544+-- > unexpected (String "oops")
545+-- > -- Error: "unexpected String"
546+unexpected :: Value -> Parser a
547+unexpected actual = fail $ "unexpected " ++ typeOf actual
548+
549+-- | JSON type of a value, name of the head constructor.
550+typeOf :: Value -> String
551+typeOf v = case v of
552+ Object _ -> "Object"
553+ Array _ -> "Array"
554+ String _ -> "String"
555+ Number _ -> "Number"
556+ Bool _ -> "Boolean"
557+ Null -> "Null"
520558
521559-------------------------------------------------------------------------------
522560-- Lifings of FromJSON and ToJSON to unary and binary type constructors
@@ -597,9 +635,8 @@ class FromJSON2 f where
597635 -> (Value -> Parser b)
598636 -> (Value -> Parser [b])
599637 -> Value -> Parser [f a b]
600− liftParseJSONList2 fa ga fb gb v = case v of
601− Array vals -> fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
602− _ -> typeMismatch "[a]" v
638+ liftParseJSONList2 fa ga fb gb = withArray "[]" $ \vals ->
639+ fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
603640
604641-- | Lift the standard 'parseJSON' function through the type constructor.
605642parseJSON2 :: (FromJSON2 f, FromJSON a, FromJSON b) => Value -> Parser (f a b)
@@ -613,7 +650,7 @@ parseJSON2 = liftParseJSON2 parseJSON parseJSONList parseJSON parseJSONList
613650-- | Helper function to use with 'liftParseJSON'. See 'Data.Aeson.ToJSON.listEncoding'.
614651listParser :: (Value -> Parser a) -> Value -> Parser [a]
615652listParser f (Array xs) = fmap V.toList (V.mapM f xs)
616−listParser _ v = typeMismatch "[a]" v
653+listParser _ v = typeMismatch "Array" v
617654{-# INLINE listParser #-}
618655
619656-------------------------------------------------------------------------------
@@ -631,69 +668,137 @@ instance (FromJSON a) => FromJSON [a] where
631668-- Functions
632669-------------------------------------------------------------------------------
633670
634−-- | @'withObject' expected f value@ applies @f@ to the 'Object' when @value@
635−-- is an 'Object' and fails using @'typeMismatch' expected@ otherwise.
671+-- | Add context to a failure message, indicating the name of the structure
672+-- being parsed.
673+--
674+-- > prependContext "MyType" (fail "[error message]")
675+-- > -- Error: "parsing MyType failed, [error message]"
676+prependContext :: String -> Parser a -> Parser a
677+prependContext name = prependFailure ("parsing " ++ name ++ " failed, ")
678+
679+-- | @'withObject' name f value@ applies @f@ to the 'Object' when @value@
680+-- is an 'Data.Aeson.Object' and fails otherwise.
681+--
682+-- ==== Error message example
683+--
684+-- > withObject "MyType" f (String "oops")
685+-- > -- Error: "parsing MyType failed, expected Object, but encountered String"
636686withObject :: String -> (Object -> Parser a) -> Value -> Parser a
637−withObject _ f (Object obj) = f obj
638−withObject expected _ v = typeMismatch expected v
687+withObject _ f (Object obj) = f obj
688+withObject name _ v = prependContext name (typeMismatch "Object" v)
639689{-# INLINE withObject #-}
640690
641−-- | @'withText' expected f value@ applies @f@ to the 'Text' when @value@ is a
642−-- 'String' and fails using @'typeMismatch' expected@ otherwise.
691+-- | @'withText' name f value@ applies @f@ to the 'Text' when @value@ is a
692+-- 'Data.Aeson.String' and fails otherwise.
693+--
694+-- ==== Error message example
695+--
696+-- > withText "MyType" f Null
697+-- > -- Error: "parsing MyType failed, expected String, but encountered Null"
643698withText :: String -> (Text -> Parser a) -> Value -> Parser a
644−withText _ f (String txt) = f txt
645−withText expected _ v = typeMismatch expected v
699+withText _ f (String txt) = f txt
700+withText name _ v = prependContext name (typeMismatch "String" v)
646701{-# INLINE withText #-}
647702
648703-- | @'withArray' expected f value@ applies @f@ to the 'Array' when @value@ is
649−-- an 'Array' and fails using @'typeMismatch' expected@ otherwise.
704+-- an 'Data.Aeson.Array' and fails otherwise.
705+--
706+-- ==== Error message example
707+--
708+-- > withArray "MyType" f (String "oops")
709+-- > -- Error: "parsing MyType failed, expected Array, but encountered String"
650710withArray :: String -> (Array -> Parser a) -> Value -> Parser a
651−withArray _ f (Array arr) = f arr
652−withArray expected _ v = typeMismatch expected v
711+withArray _ f (Array arr) = f arr
712+withArray name _ v = prependContext name (typeMismatch "Array" v)
653713{-# INLINE withArray #-}
654714
655−-- | @'withScientific' expected f value@ applies @f@ to the 'Scientific' number
656−-- when @value@ is a 'Number' and fails using @'typeMismatch' expected@
715+-- | @'withScientific' name f value@ applies @f@ to the 'Scientific' number
716+-- when @value@ is a 'Data.Aeson.Number' and fails using 'typeMismatch'
657717-- otherwise.
658−-- .
718+--
659719-- /Warning/: If you are converting from a scientific to an unbounded
660720-- type such as 'Integer' you may want to add a restriction on the
661721-- size of the exponent (see 'withBoundedScientific') to prevent
662722-- malicious input from filling up the memory of the target system.
723+--
724+-- ==== Error message example
725+--
726+-- > withScientific "MyType" f (String "oops")
727+-- > -- Error: "parsing MyType failed, expected Number, but encountered String"
663728withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
664−withScientific _ f (Number scientific) = f scientific
665−withScientific expected _ v = typeMismatch expected v
729+withScientific _ f (Number scientific) = f scientific
730+withScientific name _ v = prependContext name (typeMismatch "Number" v)
666731{-# INLINE withScientific #-}
667732
668−-- | @'withBoundedScientific' expected f value@ applies @f@ to the 'Scientific' number
669−-- when @value@ is a 'Number' and fails using @'typeMismatch' expected@
670−-- otherwise.
733+-- | A variant of 'withScientific' which doesn't use 'prependContext', so that
734+-- such context can be added separately in a way that also applies when the
735+-- continuation @f :: Scientific -> Parser a@ fails.
671736--
672−-- The conversion will also fail with a @'typeMismatch' if the
673−-- 'Scientific' exponent is larger than 1024.
737+-- /Warning/: If you are converting from a scientific to an unbounded
738+-- type such as 'Integer' you may want to add a restriction on the
739+-- size of the exponent (see 'withBoundedScientific') to prevent
740+-- malicious input from filling up the memory of the target system.
741+--
742+-- ==== Error message examples
743+--
744+-- > withScientific' f (String "oops")
745+-- > -- Error: "unexpected String"
746+-- >
747+-- > prependContext "MyType" (withScientific' f (String "oops"))
748+-- > -- Error: "parsing MyType failed, unexpected String"
749+withScientific' :: (Scientific -> Parser a) -> Value -> Parser a
750+withScientific' f v = case v of
751+ Number n -> f n
752+ _ -> typeMismatch "Number" v
753+{-# INLINE withScientific' #-}
754+
755+-- | @'withBoundedScientific' name f value@ applies @f@ to the 'Scientific' number
756+-- when @value@ is a 'Number' with exponent less than or equal to 1024.
674757withBoundedScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
675−withBoundedScientific _ f v@(Number scientific) =
676− if base10Exponent scientific > 1024
677− then typeMismatch "a number with exponent <= 1024" v
678− else f scientific
679−withBoundedScientific expected _ v = typeMismatch expected v
758+withBoundedScientific name f v = withBoundedScientific_ (prependContext name) f v
680759{-# INLINE withBoundedScientific #-}
681760
761+-- | A variant of 'withBoundedScientific' which doesn't use 'prependContext',
762+-- so that such context can be added separately in a way that also applies
763+-- when the continuation @f :: Scientific -> Parser a@ fails.
764+withBoundedScientific' :: (Scientific -> Parser a) -> Value -> Parser a
765+withBoundedScientific' f v = withBoundedScientific_ id f v
766+{-# INLINE withBoundedScientific' #-}
767+
768+-- | A variant of 'withBoundedScientific_' parameterized by a function to apply
769+-- to the 'Parser' in case of failure.
770+withBoundedScientific_ :: (Parser a -> Parser a) -> (Scientific -> Parser a) -> Value -> Parser a
771+withBoundedScientific_ whenFail f (Number scientific) =
772+ if exp10 > 1024
773+ then whenFail (fail msg)
774+ else f scientific
775+ where
776+ exp10 = base10Exponent scientific
777+ msg = "found a number with exponent " ++ show exp10 ++ ", but it must not be greater than 1024"
778+withBoundedScientific_ whenFail _ v =
779+ whenFail (typeMismatch "Number" v)
780+{-# INLINE withBoundedScientific_ #-}
781+
682782-- | @'withBool' expected f value@ applies @f@ to the 'Bool' when @value@ is a
683−-- 'Bool' and fails using @'typeMismatch' expected@ otherwise.
783+-- 'Boolean' and fails otherwise.
784+--
785+-- ==== Error message example
786+--
787+-- > withBool "MyType" f (String "oops")
788+-- > -- Error: "parsing MyType failed, expected Boolean, but encountered String"
684789withBool :: String -> (Bool -> Parser a) -> Value -> Parser a
685−withBool _ f (Bool arr) = f arr
686−withBool expected _ v = typeMismatch expected v
790+withBool _ f (Bool arr) = f arr
791+withBool name _ v = prependContext name (typeMismatch "Boolean" v)
687792{-# INLINE withBool #-}
688793
689794-- | Decode a nested JSON-encoded string.
690795withEmbeddedJSON :: String -> (Value -> Parser a) -> Value -> Parser a
691796withEmbeddedJSON _ innerParser (String txt) =
692− either fail innerParser $ eitherDecode (Compat.fromStrict $ T.encodeUtf8 txt)
797+ either fail innerParser $ eitherDecode (L.fromStrict $ T.encodeUtf8 txt)
693798 where
694799 eitherDecode = eitherFormatError . eitherDecodeWith jsonEOF ifromJSON
695800 eitherFormatError = either (Left . uncurry formatError) Right
696−withEmbeddedJSON name _ v = typeMismatch name v
801+withEmbeddedJSON name _ v = prependContext name (typeMismatch "String" v)
697802{-# INLINE withEmbeddedJSON #-}
698803
699804-- | Convert a value from JSON, failing if the types do not match.
@@ -758,7 +863,7 @@ parseFieldMaybe' = (.:!)
758863-- E.g. @'explicitParseField' 'parseJSON1' :: ('FromJSON1' f, 'FromJSON' a) -> 'Object' -> 'Text' -> 'Parser' (f a)@
759864explicitParseField :: (Value -> Parser a) -> Object -> Text -> Parser a
760865explicitParseField p obj key = case H.lookup key obj of
761− Nothing -> fail $ "key " ++ show key ++ " not present"
866+ Nothing -> fail $ "key " ++ show key ++ " not found"
762867 Just v -> p v <?> Key key
763868{-# INLINE explicitParseField #-}
764869
@@ -808,6 +913,37 @@ instance OVERLAPPABLE_ (GFromJSON arity a) => GFromJSON arity (M1 i c a) where
808913 -- parsed value:
809914 gParseJSON opts fargs = fmap M1 . gParseJSON opts fargs
810915
916+-- Information for error messages
917+
918+type TypeName = String
919+type ConName = String
920+
921+-- | Add the name of the type being parsed to a parser's error messages.
922+contextType :: TypeName -> Parser a -> Parser a
923+contextType = prependContext
924+
925+-- | Add the tagKey that will be looked up while building an ADT
926+-- | Produce the error equivalent to
927+-- | Left "Error in $: parsing T failed, expected an object with keys "tag" and
928+-- | "contents", where "tag" i-- |s associated to one of ["Foo", "Bar"],
929+-- | The parser returned error was: could not find key "tag"
930+contextTag :: Text -> [String] -> Parser a -> Parser a
931+contextTag tagKey cnames = prependFailure
932+ ("expected Object with key \"" ++ unpack tagKey ++ "\"" ++
933+ " containing one of " ++ show cnames ++ ", ")
934+
935+-- | Add the name of the constructor being parsed to a parser's error messages.
936+contextCons :: ConName -> TypeName -> Parser a -> Parser a
937+contextCons cname tname = prependContext (showCons cname tname)
938+
939+-- | Render a constructor as @\"MyType(MyConstructor)\"@.
940+showCons :: ConName -> TypeName -> String
941+showCons cname tname = tname ++ "(" ++ cname ++ ")"
942+
943+--------------------------------------------------------------------------------
944+
945+-- Parsing single fields
946+
811947instance (FromJSON a) => GFromJSON arity (K1 i a) where
812948 -- Constant values are decoded using their FromJSON instance:
813949 gParseJSON _opts _ = fmap K1 . parseJSON
@@ -822,342 +958,499 @@ instance (FromJSON1 f) => GFromJSON One (Rec1 f) where
822958 -- FromJSON1 instance:
823959 gParseJSON _opts (From1Args pj pjl) = fmap Rec1 . liftParseJSON pj pjl
824960
825−instance GFromJSON arity U1 where
826− -- Empty constructors are expected to be encoded as an empty array:
827− gParseJSON _opts _ v
828− | isEmptyArray v = pure U1
829− | otherwise = typeMismatch "unit constructor (U1)" v
961+instance (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) where
962+ -- If an occurrence of the last type parameter is nested inside two
963+ -- composed types, it is decoded by using the outermost type's FromJSON1
964+ -- instance to generically decode the innermost type:
965+ gParseJSON opts fargs =
966+ let gpj = gParseJSON opts fargs in
967+ fmap Comp1 . liftParseJSON gpj (listParser gpj)
968+
969+--------------------------------------------------------------------------------
830970
971+instance (GFromJSON' arity a, Datatype d) => GFromJSON arity (D1 d a) where
972+ -- Meta-information, which is not handled elsewhere, is just added to the
973+ -- parsed value:
974+ gParseJSON opts fargs = fmap M1 . gParseJSON' (tname :* opts :* fargs)
975+ where
976+ tname = moduleName proxy ++ "." ++ datatypeName proxy
977+ proxy = undefined :: M1 _i d _f _p
978+
979+-- | 'GFromJSON', after unwrapping the 'D1' constructor, now carrying the data
980+-- type's name.
981+class GFromJSON' arity f where
982+ gParseJSON' :: TypeName :* Options :* FromArgs arity a
983+ -> Value
984+ -> Parser (f a)
985+
986+-- | Single constructor.
831987instance ( ConsFromJSON arity a
832988 , AllNullary (C1 c a) allNullary
833989 , ParseSum arity (C1 c a) allNullary
834− ) => GFromJSON arity (D1 d (C1 c a)) where
990+ , Constructor c
991+ ) => GFromJSON' arity (C1 c a) where
835992 -- The option 'tagSingleConstructors' determines whether to wrap
836993 -- a single-constructor type.
837− gParseJSON opts fargs
994+ gParseJSON' p@(_ :* opts :* _)
838995 | tagSingleConstructors opts
839− = fmap M1
840− . (unTagged :: Tagged allNullary (Parser (C1 c a p)) -> Parser (C1 c a p))
841− . parseSum opts fargs
842− | otherwise = fmap M1 . fmap M1 . consParseJSON opts fargs
843−
844−instance (ConsFromJSON arity a) => GFromJSON arity (C1 c a) where
845− -- Constructors need to be decoded differently depending on whether they're
846− -- a record or not. This distinction is made by consParseJSON:
847− gParseJSON opts fargs = fmap M1 . consParseJSON opts fargs
848−
849−instance ( FromProduct arity a, FromProduct arity b
850− , ProductSize a, ProductSize b
851− ) => GFromJSON arity (a :*: b) where
852− -- Products are expected to be encoded to an array. Here we check whether we
853− -- got an array of the same size as the product, then parse each of the
854− -- product's elements using parseProduct:
855− gParseJSON opts fargs = withArray "product (:*:)" $ \arr ->
856− let lenArray = V.length arr
857− lenProduct = (unTagged2 :: Tagged2 (a :*: b) Int -> Int)
858− productSize in
859− if lenArray == lenProduct
860− then parseProduct opts fargs arr 0 lenProduct
861− else fail $ "When expecting a product of " ++ show lenProduct ++
862− " values, encountered an Array of " ++ show lenArray ++
863− " elements instead"
864−
865−instance ( AllNullary (a :+: b) allNullary
866− , ParseSum arity (a :+: b) allNullary
867− ) => GFromJSON arity (a :+: b) where
996+ = (unTagged :: Tagged allNullary (Parser (C1 c a p)) -> Parser (C1 c a p))
997+ . parseSum p
998+ | otherwise = fmap M1 . consParseJSON (cname :* p)
999+ where
1000+ cname = conName (undefined :: M1 _i c _f _p)
1001+
1002+-- | Multiple constructors.
1003+instance ( AllNullary (a :+: b) allNullary
1004+ , ParseSum arity (a :+: b) allNullary
1005+ ) => GFromJSON' arity (a :+: b) where
8681006 -- If all constructors of a sum datatype are nullary and the
8691007 -- 'allNullaryToStringTag' option is set they are expected to be
8701008 -- encoded as strings. This distinction is made by 'parseSum':
871− gParseJSON opts fargs =
872− (unTagged :: Tagged allNullary (Parser ((a :+: b) d)) ->
873− Parser ((a :+: b) d))
874− . parseSum opts fargs
875−
876−instance (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) where
877− -- If an occurrence of the last type parameter is nested inside two
878− -- composed types, it is decoded by using the outermost type's FromJSON1
879− -- instance to generically decode the innermost type:
880− gParseJSON opts fargs =
881− let gpj = gParseJSON opts fargs in
882− fmap Comp1 . liftParseJSON gpj (listParser gpj)
1009+ gParseJSON' p =
1010+ (unTagged :: Tagged allNullary (Parser ((a :+: b) _d)) ->
1011+ Parser ((a :+: b) _d))
1012+ . parseSum p
8831013
8841014--------------------------------------------------------------------------------
8851015
8861016class ParseSum arity f allNullary where
887− parseSum :: Options -> FromArgs arity a
888− -> Value -> Tagged allNullary (Parser (f a))
1017+ parseSum :: TypeName :* Options :* FromArgs arity a
1018+ -> Value
1019+ -> Tagged allNullary (Parser (f a))
8891020
890−instance ( SumFromString f
1021+instance ( ConstructorNames f
1022+ , SumFromString f
8911023 , FromPair arity f
8921024 , FromTaggedObject arity f
8931025 , FromUntaggedValue arity f
8941026 ) => ParseSum arity f True where
895− parseSum opts fargs
896− | allNullaryToStringTag opts = Tagged . parseAllNullarySum opts
897− | otherwise = Tagged . parseNonAllNullarySum opts fargs
1027+ parseSum p@(tname :* opts :* _)
1028+ | allNullaryToStringTag opts = Tagged . parseAllNullarySum tname opts
1029+ | otherwise = Tagged . parseNonAllNullarySum p
8981030
899−instance ( FromPair arity f
1031+instance ( ConstructorNames f
1032+ , FromPair arity f
9001033 , FromTaggedObject arity f
9011034 , FromUntaggedValue arity f
9021035 ) => ParseSum arity f False where
903− parseSum opts fargs = Tagged . parseNonAllNullarySum opts fargs
1036+ parseSum p = Tagged . parseNonAllNullarySum p
9041037
9051038--------------------------------------------------------------------------------
9061039
907−parseAllNullarySum :: SumFromString f => Options -> Value -> Parser (f a)
908−parseAllNullarySum opts = withText "Text" $ \key ->
909− maybe (notFound key) return $
910− parseSumFromString opts key
1040+parseAllNullarySum :: (SumFromString f, ConstructorNames f)
1041+ => TypeName -> Options -> Value -> Parser (f a)
1042+parseAllNullarySum tname opts =
1043+ withText tname $ \tag ->
1044+ maybe (badTag tag) return $
1045+ parseSumFromString modifier tag
1046+ where
1047+ badTag tag = failWithCTags tname modifier $ \cnames ->
1048+ "expected one of the tags " ++ show cnames ++
1049+ ", but found tag " ++ show tag
1050+ modifier = constructorTagModifier opts
1051+
1052+-- | Fail with an informative error message about a mismatched tag.
1053+-- The error message is parameterized by the list of expected tags,
1054+-- to be inferred from the result type of the parser.
1055+failWithCTags
1056+ :: forall f a t. ConstructorNames f
1057+ => TypeName -> (String -> t) -> ([t] -> String) -> Parser (f a)
1058+failWithCTags tname modifier f =
1059+ contextType tname . fail $ f cnames
1060+ where
1061+ cnames = unTagged2 (constructorTags modifier :: Tagged2 f [t])
9111062
9121063class SumFromString f where
913− parseSumFromString :: Options -> Text -> Maybe (f a)
1064+ parseSumFromString :: (String -> String) -> Text -> Maybe (f a)
9141065
9151066instance (SumFromString a, SumFromString b) => SumFromString (a :+: b) where
9161067 parseSumFromString opts key = (L1 <$> parseSumFromString opts key) <|>
9171068 (R1 <$> parseSumFromString opts key)
9181069
9191070instance (Constructor c) => SumFromString (C1 c U1) where
920− parseSumFromString opts key | key == name = Just $ M1 U1
921− | otherwise = Nothing
922− where
923− name = pack $ constructorTagModifier opts $
924− conName (undefined :: t c U1 p)
1071+ parseSumFromString modifier key
1072+ | key == name = Just $ M1 U1
1073+ | otherwise = Nothing
1074+ where
1075+ name = pack $ modifier $ conName (undefined :: M1 _i c _f _p)
9251076
926−--------------------------------------------------------------------------------
1077+-- For genericFromJSONKey
1078+instance SumFromString a => SumFromString (D1 d a) where
1079+ parseSumFromString modifier key = M1 <$> parseSumFromString modifier key
1080+
1081+-- | List of all constructor tags.
1082+constructorTags :: ConstructorNames a => (String -> t) -> Tagged2 a [t]
1083+constructorTags modifier =
1084+ fmap DList.toList (constructorNames' modifier)
1085+
1086+-- | List of all constructor names of an ADT, after a given conversion
1087+-- function. (Better inlining.)
1088+class ConstructorNames a where
1089+ constructorNames' :: (String -> t) -> Tagged2 a (DList.DList t)
1090+
1091+instance (ConstructorNames a, ConstructorNames b) => ConstructorNames (a :+: b) where
1092+ constructorNames' = liftA2 append constructorNames' constructorNames'
1093+ where
1094+ append
1095+ :: Tagged2 a (DList.DList t)
1096+ -> Tagged2 b (DList.DList t)
1097+ -> Tagged2 (a :+: b) (DList.DList t)
1098+ append (Tagged2 xs) (Tagged2 ys) = Tagged2 (DList.append xs ys)
1099+
1100+instance Constructor c => ConstructorNames (C1 c a) where
1101+ constructorNames' f = Tagged2 (pure (f cname))
1102+ where
1103+ cname = conName (undefined :: M1 _i c _f _p)
9271104
928−parseNonAllNullarySum :: ( FromPair arity f
1105+-- For genericFromJSONKey
1106+instance ConstructorNames a => ConstructorNames (D1 d a) where
1107+ constructorNames' = retag . constructorNames'
1108+ where
1109+ retag :: Tagged2 a u -> Tagged2 (D1 d a) u
1110+ retag (Tagged2 x) = Tagged2 x
1111+
1112+--------------------------------------------------------------------------------
1113+parseNonAllNullarySum :: forall f c arity.
1114+ ( FromPair arity f
9291115 , FromTaggedObject arity f
9301116 , FromUntaggedValue arity f
931− ) => Options -> FromArgs arity c
1117+ , ConstructorNames f
1118+ ) => TypeName :* Options :* FromArgs arity c
9321119 -> Value -> Parser (f c)
933−parseNonAllNullarySum opts fargs =
1120+parseNonAllNullarySum p@(tname :* opts :* _) =
9341121 case sumEncoding opts of
9351122 TaggedObject{..} ->
936− withObject "Object" $ \obj -> do
937− tag <- obj .: pack tagFieldName
938− fromMaybe (notFound tag) $
939− parseFromTaggedObject opts fargs contentsFieldName obj tag
1123+ withObject tname $ \obj -> do
1124+ tag <- contextType tname . contextTag tagKey cnames_ $ obj .: tagKey
1125+ fromMaybe (badTag tag <?> Key tagKey) $
1126+ parseFromTaggedObject (tag :* contentsFieldName :* p) obj
1127+ where
1128+ tagKey = pack tagFieldName
1129+ badTag tag = failWith_ $ \cnames ->
1130+ "expected tag field to be one of " ++ show cnames ++
1131+ ", but found tag " ++ show tag
1132+ cnames_ = unTagged2 (constructorTags (constructorTagModifier opts) :: Tagged2 f [String])
9401133
9411134 ObjectWithSingleField ->
942− withObject "Object" $ \obj ->
943− case H.toList obj of
944− [pair@(tag, _)] -> fromMaybe (notFound tag) $
945− parsePair opts fargs pair
946− _ -> fail "Object doesn't have a single field"
1135+ withObject tname $ \obj -> case H.toList obj of
1136+ [(tag, v)] -> maybe (badTag tag) (<?> Key tag) $
1137+ parsePair (tag :* p) v
1138+ _ -> contextType tname . fail $
1139+ "expected an Object with a single pair, but found " ++
1140+ show (H.size obj) ++ " pairs"
1141+ where
1142+ badTag tag = failWith_ $ \cnames ->
1143+ "expected an Object with a single pair where the tag is one of " ++
1144+ show cnames ++ ", but found tag " ++ show tag
9471145
9481146 TwoElemArray ->
949− withArray "Array" $ \arr ->
950− if V.length arr == 2
951− then case V.unsafeIndex arr 0 of
952− String tag -> fromMaybe (notFound tag) $
953− parsePair opts fargs (tag, V.unsafeIndex arr 1)
954− _ -> fail "First element is not a String"
955− else fail "Array doesn't have 2 elements"
1147+ withArray tname $ \arr -> case V.length arr of
1148+ 2 | String tag <- V.unsafeIndex arr 0 ->
1149+ maybe (badTag tag <?> Index 0) (<?> Index 1) $
1150+ parsePair (tag :* p) (V.unsafeIndex arr 1)
1151+ | otherwise ->
1152+ contextType tname $
1153+ fail "tag element is not a String" <?> Index 0
1154+ len -> contextType tname . fail $
1155+ "expected a 2-element Array, but encountered an Array of length " ++
1156+ show len
1157+ where
1158+ badTag tag = failWith_ $ \cnames ->
1159+ "expected tag of the 2-element Array to be one of " ++
1160+ show cnames ++ ", but found tag " ++ show tag
9561161
957− UntaggedValue -> parseUntaggedValue opts fargs
1162+ UntaggedValue -> parseUntaggedValue p
1163+ where
1164+ failWith_ = failWithCTags tname (constructorTagModifier opts)
9581165
9591166--------------------------------------------------------------------------------
9601167
9611168class FromTaggedObject arity f where
962− parseFromTaggedObject :: Options -> FromArgs arity a
963− -> String -> Object
964− -> Text -> Maybe (Parser (f a))
1169+ -- The first two components of the parameter tuple are: the constructor tag
1170+ -- to match against, and the contents field name.
1171+ parseFromTaggedObject
1172+ :: Text :* String :* TypeName :* Options :* FromArgs arity a
1173+ -> Object
1174+ -> Maybe (Parser (f a))
9651175
9661176instance ( FromTaggedObject arity a, FromTaggedObject arity b) =>
9671177 FromTaggedObject arity (a :+: b) where
968− parseFromTaggedObject opts fargs contentsFieldName obj tag =
969− (fmap L1 <$> parseFromTaggedObject opts fargs contentsFieldName obj tag) <|>
970− (fmap R1 <$> parseFromTaggedObject opts fargs contentsFieldName obj tag)
1178+ parseFromTaggedObject p obj =
1179+ (fmap L1 <$> parseFromTaggedObject p obj) <|>
1180+ (fmap R1 <$> parseFromTaggedObject p obj)
9711181
972−instance ( FromTaggedObject' arity f
1182+instance ( IsRecord f isRecord
1183+ , FromTaggedObject' arity f isRecord
9731184 , Constructor c
9741185 ) => FromTaggedObject arity (C1 c f) where
975− parseFromTaggedObject opts fargs contentsFieldName obj tag
976− | tag == name = Just $ M1 <$> parseFromTaggedObject'
977− opts fargs contentsFieldName obj
978− | otherwise = Nothing
979− where
980− name = pack $ constructorTagModifier opts $
981− conName (undefined :: t c f p)
1186+ parseFromTaggedObject (tag :* contentsFieldName :* p@(_ :* opts :* _))
1187+ | tag == tag'
1188+ = Just . fmap M1 .
1189+ (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a)) .
1190+ parseFromTaggedObject' (contentsFieldName :* cname :* p)
1191+ | otherwise = const Nothing
1192+ where
1193+ tag' = pack $ constructorTagModifier opts cname
1194+ cname = conName (undefined :: M1 _i c _f _p)
9821195
9831196--------------------------------------------------------------------------------
9841197
985−class FromTaggedObject' arity f where
986− parseFromTaggedObject' :: Options -> FromArgs arity a -> String
987− -> Object -> Parser (f a)
988−
989−class FromTaggedObject'' arity f isRecord where
990− parseFromTaggedObject'' :: Options -> FromArgs arity a -> String
991− -> Object -> Tagged isRecord (Parser (f a))
992−
993−instance ( IsRecord f isRecord
994− , FromTaggedObject'' arity f isRecord
995− ) => FromTaggedObject' arity f where
996− parseFromTaggedObject' opts fargs contentsFieldName =
997− (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a)) .
998− parseFromTaggedObject'' opts fargs contentsFieldName
999−
1000−instance (FromRecord arity f) => FromTaggedObject'' arity f True where
1001− parseFromTaggedObject'' opts fargs _ =
1002− Tagged . parseRecord opts fargs
1003−
1004−instance (GFromJSON arity f) => FromTaggedObject'' arity f False where
1005− parseFromTaggedObject'' opts fargs contentsFieldName = Tagged .
1006− (gParseJSON opts fargs <=< (.: pack contentsFieldName))
1198+class FromTaggedObject' arity f isRecord where
1199+ -- The first component of the parameter tuple is the contents field name.
1200+ parseFromTaggedObject'
1201+ :: String :* ConName :* TypeName :* Options :* FromArgs arity a
1202+ -> Object -> Tagged isRecord (Parser (f a))
1203+
1204+instance (RecordFromJSON arity f, FieldNames f) => FromTaggedObject' arity f True where
1205+ -- Records are unpacked in the tagged object
1206+ parseFromTaggedObject' (_ :* p) = Tagged . recordParseJSON (True :* p)
1207+
1208+instance (ConsFromJSON arity f) => FromTaggedObject' arity f False where
1209+ -- Nonnullary nonrecords are encoded in the contents field
1210+ parseFromTaggedObject' p obj = Tagged $ do
1211+ contents <- contextCons cname tname (obj .: key)
1212+ consParseJSON p' contents <?> Key key
1213+ where
1214+ key = pack contentsFieldName
1215+ contentsFieldName :* p'@(cname :* tname :* _) = p
10071216
1008−instance OVERLAPPING_ FromTaggedObject'' arity U1 False where
1009− parseFromTaggedObject'' _ _ _ _ = Tagged (pure U1)
1217+instance OVERLAPPING_ FromTaggedObject' arity U1 False where
1218+ -- Nullary constructors don't need a contents field
1219+ parseFromTaggedObject' _ _ = Tagged (pure U1)
10101220
10111221--------------------------------------------------------------------------------
10121222
1223+-- | Constructors need to be decoded differently depending on whether they're
1224+-- a record or not. This distinction is made by 'ConsParseJSON'.
10131225class ConsFromJSON arity f where
1014− consParseJSON :: Options -> FromArgs arity a
1015− -> Value -> Parser (f a)
1226+ consParseJSON
1227+ :: ConName :* TypeName :* Options :* FromArgs arity a
1228+ -> Value -> Parser (f a)
10161229
10171230class ConsFromJSON' arity f isRecord where
1018− consParseJSON' :: Options -> FromArgs arity a
1019− -> Value -> Tagged isRecord (Parser (f a))
1231+ consParseJSON'
1232+ :: ConName :* TypeName :* Options :* FromArgs arity a
1233+ -> Value -> Tagged isRecord (Parser (f a))
10201234
10211235instance ( IsRecord f isRecord
10221236 , ConsFromJSON' arity f isRecord
10231237 ) => ConsFromJSON arity f where
1024− consParseJSON opts fargs =
1238+ consParseJSON p =
10251239 (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
1026− . consParseJSON' opts fargs
1240+ . consParseJSON' p
10271241
10281242instance OVERLAPPING_
1029− ( GFromJSON arity a, FromRecord arity (S1 s a)
1243+ ( GFromJSON arity a, RecordFromJSON arity (S1 s a)
10301244 ) => ConsFromJSON' arity (S1 s a) True where
1031− consParseJSON' opts fargs
1032− | unwrapUnaryRecords opts = Tagged . gParseJSON opts fargs
1033− | otherwise = Tagged . withObject "unary record" (parseRecord opts fargs)
1245+ consParseJSON' p@(cname :* tname :* opts :* fargs)
1246+ | unwrapUnaryRecords opts = Tagged . fmap M1 . gParseJSON opts fargs
1247+ | otherwise = Tagged . withObject (showCons cname tname) (recordParseJSON (False :* p))
10341248
1035−instance FromRecord arity f => ConsFromJSON' arity f True where
1036− consParseJSON' opts fargs =
1037− Tagged . withObject "record (:*:)" (parseRecord opts fargs)
1249+instance RecordFromJSON arity f => ConsFromJSON' arity f True where
1250+ consParseJSON' p@(cname :* tname :* _) =
1251+ Tagged . withObject (showCons cname tname) (recordParseJSON (False :* p))
10381252
1039−instance GFromJSON arity f => ConsFromJSON' arity f False where
1040− consParseJSON' opts fargs = Tagged . gParseJSON opts fargs
1253+instance OVERLAPPING_
1254+ ConsFromJSON' arity U1 False where
1255+ -- Empty constructors are expected to be encoded as an empty array:
1256+ consParseJSON' (cname :* tname :* _) v =
1257+ Tagged . contextCons cname tname $ case v of
1258+ Array a | V.null a -> pure U1
1259+ | otherwise -> fail_ a
1260+ _ -> typeMismatch "Array" v
1261+ where
1262+ fail_ a = fail $
1263+ "expected an empty Array, but encountered an Array of length " ++
1264+ show (V.length a)
1265+
1266+instance OVERLAPPING_
1267+ GFromJSON arity f => ConsFromJSON' arity (S1 s f) False where
1268+ consParseJSON' (_ :* _ :* opts :* fargs) =
1269+ Tagged . fmap M1 . gParseJSON opts fargs
1270+
1271+instance (ProductFromJSON arity f, ProductSize f
1272+ ) => ConsFromJSON' arity f False where
1273+ consParseJSON' p = Tagged . productParseJSON0 p
10411274
10421275--------------------------------------------------------------------------------
10431276
1044−class FromRecord arity f where
1045− parseRecord :: Options -> FromArgs arity a
1046− -> Object -> Parser (f a)
1277+class FieldNames f where
1278+ fieldNames :: f a -> [Text] -> [Text]
10471279
1048−instance ( FromRecord arity a
1049− , FromRecord arity b
1050− ) => FromRecord arity (a :*: b) where
1051− parseRecord opts fargs obj =
1052− (:*:) <$> parseRecord opts fargs obj
1053− <*> parseRecord opts fargs obj
1280+instance (FieldNames a, FieldNames b) => FieldNames (a :*: b) where
1281+ fieldNames _ =
1282+ fieldNames (undefined :: a x) .
1283+ fieldNames (undefined :: b y)
10541284
1055−instance OVERLAPPABLE_ (Selector s, GFromJSON arity a) =>
1056− FromRecord arity (S1 s a) where
1057− parseRecord opts fargs =
1058− (<?> Key label) . gParseJSON opts fargs <=< (.: label)
1285+instance (Selector s) => FieldNames (S1 s f) where
1286+ fieldNames _ = (pack (selName (undefined :: M1 _i s _f _p)) :)
1287+
1288+class RecordFromJSON arity f where
1289+ recordParseJSON
1290+ :: Bool :* ConName :* TypeName :* Options :* FromArgs arity a
1291+ -> Object -> Parser (f a)
1292+
1293+instance ( FieldNames f
1294+ , RecordFromJSON' arity f
1295+ ) => RecordFromJSON arity f where
1296+ recordParseJSON (fromTaggedSum :* p@(cname :* tname :* opts :* _)) =
1297+ \obj -> checkUnknown obj >> recordParseJSON' p obj
10591298 where
1060− label = pack . fieldLabelModifier opts $ selName (undefined :: t s a p)
1299+ knownFields :: H.HashMap Text ()
1300+ knownFields = H.fromList $ map (,()) $
1301+ fieldNames (undefined :: f a)
1302+ [pack (tagFieldName (sumEncoding opts)) | fromTaggedSum]
1303+ checkUnknown =
1304+ if not (rejectUnknownFields opts)
1305+ then \_ -> return ()
1306+ else \obj -> case H.keys (H.difference obj knownFields) of
1307+ [] -> return ()
1308+ unknownFields -> contextCons cname tname $
1309+ fail ("unknown fields: " ++ show unknownFields)
1310+
1311+class RecordFromJSON' arity f where
1312+ recordParseJSON'
1313+ :: ConName :* TypeName :* Options :* FromArgs arity a
1314+ -> Object -> Parser (f a)
1315+
1316+instance ( RecordFromJSON' arity a
1317+ , RecordFromJSON' arity b
1318+ ) => RecordFromJSON' arity (a :*: b) where
1319+ recordParseJSON' p obj =
1320+ (:*:) <$> recordParseJSON' p obj
1321+ <*> recordParseJSON' p obj
1322+
1323+instance OVERLAPPABLE_ (Selector s, GFromJSON arity a) =>
1324+ RecordFromJSON' arity (S1 s a) where
1325+ recordParseJSON' (cname :* tname :* opts :* fargs) obj = do
1326+ fv <- contextCons cname tname (obj .: label)
1327+ M1 <$> gParseJSON opts fargs fv <?> Key label
1328+ where
1329+ label = pack $ fieldLabelModifier opts sname
1330+ sname = selName (undefined :: M1 _i s _f _p)
10611331
10621332instance INCOHERENT_ (Selector s, FromJSON a) =>
1063− FromRecord arity (S1 s (K1 i (Maybe a))) where
1064− parseRecord opts _ obj = M1 . K1 <$> obj .:? pack label
1065− where
1066− label = fieldLabelModifier opts $
1067− selName (undefined :: t s (K1 i (Maybe a)) p)
1333+ RecordFromJSON' arity (S1 s (K1 i (Maybe a))) where
1334+ recordParseJSON' (_ :* _ :* opts :* _) obj = M1 . K1 <$> obj .:? pack label
1335+ where
1336+ label = fieldLabelModifier opts sname
1337+ sname = selName (undefined :: M1 _i s _f _p)
10681338
10691339-- Parse an Option like a Maybe.
10701340instance INCOHERENT_ (Selector s, FromJSON a) =>
1071− FromRecord arity (S1 s (K1 i (Semigroup.Option a))) where
1072− parseRecord opts fargs obj = wrap <$> parseRecord opts fargs obj
1341+ RecordFromJSON' arity (S1 s (K1 i (Semigroup.Option a))) where
1342+ recordParseJSON' p obj = wrap <$> recordParseJSON' p obj
10731343 where
10741344 wrap :: S1 s (K1 i (Maybe a)) p -> S1 s (K1 i (Semigroup.Option a)) p
10751345 wrap (M1 (K1 a)) = M1 (K1 (Semigroup.Option a))
10761346
10771347--------------------------------------------------------------------------------
10781348
1079−class FromProduct arity f where
1080− parseProduct :: Options -> FromArgs arity a
1349+productParseJSON0
1350+ :: forall f arity a. (ProductFromJSON arity f, ProductSize f)
1351+ => ConName :* TypeName :* Options :* FromArgs arity a
1352+ -> Value -> Parser (f a)
1353+ -- Products are expected to be encoded to an array. Here we check whether we
1354+ -- got an array of the same size as the product, then parse each of the
1355+ -- product's elements using productParseJSON:
1356+productParseJSON0 p@(cname :* tname :* _ :* _) =
1357+ withArray (showCons cname tname) $ \arr ->
1358+ let lenArray = V.length arr
1359+ lenProduct = (unTagged2 :: Tagged2 f Int -> Int)
1360+ productSize in
1361+ if lenArray == lenProduct
1362+ then productParseJSON p arr 0 lenProduct
1363+ else contextCons cname tname $
1364+ fail $ "expected an Array of length " ++ show lenProduct ++
1365+ ", but encountered an Array of length " ++ show lenArray
1366+
1367+--
1368+
1369+class ProductFromJSON arity f where
1370+ productParseJSON :: ConName :* TypeName :* Options :* FromArgs arity a
10811371 -> Array -> Int -> Int
10821372 -> Parser (f a)
10831373
1084−instance ( FromProduct arity a
1085− , FromProduct arity b
1086− ) => FromProduct arity (a :*: b) where
1087− parseProduct opts fargs arr ix len =
1088− (:*:) <$> parseProduct opts fargs arr ix lenL
1089− <*> parseProduct opts fargs arr ixR lenR
1374+instance ( ProductFromJSON arity a
1375+ , ProductFromJSON arity b
1376+ ) => ProductFromJSON arity (a :*: b) where
1377+ productParseJSON p arr ix len =
1378+ (:*:) <$> productParseJSON p arr ix lenL
1379+ <*> productParseJSON p arr ixR lenR
10901380 where
10911381 lenL = len `unsafeShiftR` 1
10921382 ixR = ix + lenL
10931383 lenR = len - lenL
10941384
1095−instance (GFromJSON arity a) => FromProduct arity (S1 s a) where
1096− parseProduct opts fargs arr ix _ =
1097− gParseJSON opts fargs $ V.unsafeIndex arr ix
1385+instance (GFromJSON arity a) => ProductFromJSON arity (S1 s a) where
1386+ productParseJSON (_ :* _ :* opts :* fargs) arr ix _ =
1387+ M1 <$> gParseJSON opts fargs (V.unsafeIndex arr ix) <?> Index ix
10981388
10991389--------------------------------------------------------------------------------
11001390
11011391class FromPair arity f where
1102− parsePair :: Options -> FromArgs arity a
1103− -> Pair -> Maybe (Parser (f a))
1392+ -- The first component of the parameter tuple is the tag to match.
1393+ parsePair :: Text :* TypeName :* Options :* FromArgs arity a
1394+ -> Value
1395+ -> Maybe (Parser (f a))
11041396
11051397instance ( FromPair arity a
11061398 , FromPair arity b
11071399 ) => FromPair arity (a :+: b) where
1108− parsePair opts fargs pair = (fmap L1 <$> parsePair opts fargs pair) <|>
1109− (fmap R1 <$> parsePair opts fargs pair)
1400+ parsePair p pair =
1401+ (fmap L1 <$> parsePair p pair) <|>
1402+ (fmap R1 <$> parsePair p pair)
11101403
11111404instance ( Constructor c
1112− , GFromJSON arity a
11131405 , ConsFromJSON arity a
11141406 ) => FromPair arity (C1 c a) where
1115− parsePair opts fargs (tag, value)
1116− | tag == tag' = Just $ gParseJSON opts fargs value
1407+ parsePair (tag :* p@(_ :* opts :* _)) v
1408+ | tag == tag' = Just $ M1 <$> consParseJSON (cname :* p) v
11171409 | otherwise = Nothing
1118− where
1119− tag' = pack $ constructorTagModifier opts $
1120− conName (undefined :: t c a p)
1410+ where
1411+ tag' = pack $ constructorTagModifier opts cname
1412+ cname = conName (undefined :: M1 _i c _a _p)
11211413
11221414--------------------------------------------------------------------------------
11231415
11241416class FromUntaggedValue arity f where
1125− parseUntaggedValue :: Options -> FromArgs arity a
1126− -> Value -> Parser (f a)
1417+ parseUntaggedValue :: TypeName :* Options :* FromArgs arity a
1418+ -> Value
1419+ -> Parser (f a)
11271420
11281421instance
11291422 ( FromUntaggedValue arity a
11301423 , FromUntaggedValue arity b
11311424 ) => FromUntaggedValue arity (a :+: b)
11321425 where
1133− parseUntaggedValue opts fargs value =
1134− L1 <$> parseUntaggedValue opts fargs value <|>
1135− R1 <$> parseUntaggedValue opts fargs value
1426+ parseUntaggedValue p value =
1427+ L1 <$> parseUntaggedValue p value <|>
1428+ R1 <$> parseUntaggedValue p value
11361429
11371430instance OVERLAPPABLE_
1138− ( GFromJSON arity a
1139− , ConsFromJSON arity a
1431+ ( ConsFromJSON arity a
1432+ , Constructor c
11401433 ) => FromUntaggedValue arity (C1 c a)
11411434 where
1142− parseUntaggedValue = gParseJSON
1435+ parseUntaggedValue p = fmap M1 . consParseJSON (cname :* p)
1436+ where
1437+ cname = conName (undefined :: M1 _i c _f _p)
11431438
11441439instance OVERLAPPING_
11451440 ( Constructor c )
11461441 => FromUntaggedValue arity (C1 c U1)
11471442 where
1148− parseUntaggedValue opts _ (String s)
1149− | s == pack (constructorTagModifier opts (conName (undefined :: t c U1 p))) =
1150− pure $ M1 U1
1151− | otherwise =
1152− fail $ "Invalid tag: " ++ unpack s
1153− parseUntaggedValue _ _ v = typeMismatch (conName (undefined :: t c U1 p)) v
1154−
1155−
1156−--------------------------------------------------------------------------------
1157−
1158−notFound :: Text -> Parser a
1159−notFound key = fail $ "The key \"" ++ unpack key ++ "\" was not found"
1160−{-# INLINE notFound #-}
1443+ parseUntaggedValue (tname :* opts :* _) v =
1444+ contextCons cname tname $ case v of
1445+ String tag
1446+ | tag == tag' -> pure $ M1 U1
1447+ | otherwise -> fail_ tag
1448+ _ -> typeMismatch "String" v
1449+ where
1450+ tag' = pack $ constructorTagModifier opts cname
1451+ cname = conName (undefined :: M1 _i c _f _p)
1452+ fail_ tag = fail $
1453+ "expected tag " ++ show tag' ++ ", but found tag " ++ show tag
11611454
11621455-------------------------------------------------------------------------------
11631456-- Instances
@@ -1220,14 +1513,15 @@ instance FromJSON Void where
12201513 {-# INLINE parseJSON #-}
12211514
12221515instance FromJSON Bool where
1223− parseJSON = withBool "Bool" pure
1516+ parseJSON (Bool b) = pure b
1517+ parseJSON v = typeMismatch "Bool" v
12241518 {-# INLINE parseJSON #-}
12251519
12261520instance FromJSONKey Bool where
12271521 fromJSONKey = FromJSONKeyTextParser $ \t -> case t of
12281522 "true" -> pure True
12291523 "false" -> pure False
1230− _ -> fail $ "Cannot parse key into Bool: " ++ T.unpack t
1524+ _ -> fail $ "cannot parse key " ++ show t ++ " into Bool"
12311525
12321526instance FromJSON Ordering where
12331527 parseJSON = withText "Ordering" $ \s ->
@@ -1235,25 +1529,30 @@ instance FromJSON Ordering where
12351529 "LT" -> return LT
12361530 "EQ" -> return EQ
12371531 "GT" -> return GT
1238− _ -> fail "Parsing Ordering value failed: expected \"LT\", \"EQ\", or \"GT\""
1532+ _ -> fail $ "parsing Ordering failed, unexpected " ++ show s ++
1533+ " (expected \"LT\", \"EQ\", or \"GT\")"
12391534
12401535instance FromJSON () where
12411536 parseJSON = withArray "()" $ \v ->
12421537 if V.null v
12431538 then pure ()
1244− else fail "Expected an empty array"
1539+ else prependContext "()" $ fail "expected an empty array"
12451540 {-# INLINE parseJSON #-}
12461541
12471542instance FromJSON Char where
1248− parseJSON = withText "Char" $ \t ->
1249− if T.compareLength t 1 == EQ
1250− then pure $ T.head t
1251− else fail "Expected a string of length 1"
1543+ parseJSON = withText "Char" parseChar
12521544 {-# INLINE parseJSON #-}
12531545
1254− parseJSONList = withText "String" $ pure . T.unpack
1546+ parseJSONList (String s) = pure (T.unpack s)
1547+ parseJSONList v = typeMismatch "String" v
12551548 {-# INLINE parseJSONList #-}
12561549
1550+parseChar :: Text -> Parser Char
1551+parseChar t =
1552+ if T.compareLength t 1 == EQ
1553+ then pure $ T.head t
1554+ else prependContext "Char" $ fail "expected a string of length 1"
1555+
12571556instance FromJSON Double where
12581557 parseJSON = parseRealFloat "Double"
12591558 {-# INLINE parseJSON #-}
@@ -1277,12 +1576,22 @@ instance FromJSONKey Float where
12771576 _ -> Scientific.toRealFloat <$> parseScientificText t
12781577
12791578instance (FromJSON a, Integral a) => FromJSON (Ratio a) where
1280− parseJSON = withObject "Rational" $ \obj -> do
1281− numerator <- obj .: "numerator"
1282− denominator <- obj .: "denominator"
1283− if denominator == 0
1284− then fail "Ratio denominator was 0"
1285− else pure $ numerator % denominator
1579+ parseJSON (Number x)
1580+ | exp10 <= 1024
1581+ , exp10 >= -1024 = return $! realToFrac x
1582+ | otherwise = prependContext "Ratio" $ fail msg
1583+ where
1584+ exp10 = base10Exponent x
1585+ msg = "found a number with exponent " ++ show exp10
1586+ ++ ", but it must not be greater than 1024 or less than -1024"
1587+ parseJSON o = objParser o
1588+ where
1589+ objParser = withObject "Rational" $ \obj -> do
1590+ numerator <- obj .: "numerator"
1591+ denominator <- obj .: "denominator"
1592+ if denominator == 0
1593+ then fail "Ratio denominator was 0"
1594+ else pure $ numerator % denominator
12861595 {-# INLINE parseJSON #-}
12871596
12881597-- | This instance includes a bounds check to prevent maliciously
@@ -1290,7 +1599,7 @@ instance (FromJSON a, Integral a) => FromJSON (Ratio a) where
12901599-- newtype 'Scientific' and provide your own instance using
12911600-- 'withScientific' if you want to allow larger inputs.
12921601instance HasResolution a => FromJSON (Fixed a) where
1293− parseJSON = withBoundedScientific "Fixed" $ pure . realToFrac
1602+ parseJSON = prependContext "Fixed" . withBoundedScientific' (pure . realToFrac)
12941603 {-# INLINE parseJSON #-}
12951604
12961605instance FromJSON Int where
@@ -1313,19 +1622,20 @@ instance FromJSONKey Integer where
13131622
13141623instance FromJSON Natural where
13151624 parseJSON value = do
1316− integer :: Integer <- parseIntegral "Natural" value
1317− if integer < 0 then
1318− fail $ "expected Natural, encountered negative number " <> show integer
1319− else
1320− pure $ fromIntegral integer
1625+ integer <- parseIntegral "Natural" value
1626+ parseNatural integer
13211627
13221628instance FromJSONKey Natural where
13231629 fromJSONKey = FromJSONKeyTextParser $ \text -> do
1324− integer :: Integer <- parseIntegralText "Natural" text
1325− if integer < 0 then
1326− fail $ "expected Natural, encountered negative number " <> show integer
1327− else
1328− pure $ fromIntegral integer
1630+ integer <- parseIntegralText "Natural" text
1631+ parseNatural integer
1632+
1633+parseNatural :: Integer -> Parser Natural
1634+parseNatural integer =
1635+ if integer < 0 then
1636+ fail $ "parsing Natural failed, unexpected negative number " <> show integer
1637+ else
1638+ pure $ fromIntegral integer
13291639
13301640instance FromJSON Int8 where
13311641 parseJSON = parseBoundedIntegral "Int8"
@@ -1422,17 +1732,17 @@ parseVersionText = go . readP_to_S parseVersion . unpack
14221732 where
14231733 go [(v,[])] = return v
14241734 go (_ : xs) = go xs
1425− go _ = fail "could not parse Version"
1735+ go _ = fail "parsing Version failed"
14261736
14271737-------------------------------------------------------------------------------
14281738-- semigroups NonEmpty
14291739-------------------------------------------------------------------------------
14301740
14311741instance FromJSON1 NonEmpty where
1432− liftParseJSON p _ = withArray "NonEmpty a" $
1742+ liftParseJSON p _ = withArray "NonEmpty" $
14331743 (>>= ne) . Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
14341744 where
1435− ne [] = fail "Expected a NonEmpty but got an empty list"
1745+ ne [] = fail "parsing NonEmpty failed, unexpected empty list"
14361746 ne (x:xs) = pure (x :| xs)
14371747 {-# INLINE liftParseJSON #-}
14381748
@@ -1453,7 +1763,7 @@ instance FromJSON Scientific where
14531763-------------------------------------------------------------------------------
14541764
14551765instance FromJSON1 DList.DList where
1456− liftParseJSON p _ = withArray "DList a" $
1766+ liftParseJSON p _ = withArray "DList" $
14571767 fmap DList.fromList .
14581768 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
14591769 {-# INLINE liftParseJSON #-}
@@ -1530,7 +1840,7 @@ instance (FromJSON1 f, FromJSON1 g) => FromJSON1 (Sum f g) where
15301840 inr = "InR"
15311841
15321842 liftParseJSON _ _ _ = fail $
1533− "expected an object with a single property " ++
1843+ "parsing Sum failed, expected an object with a single property " ++
15341844 "where the property key should be either " ++
15351845 "\"InL\" or \"InR\""
15361846 {-# INLINE liftParseJSON #-}
@@ -1544,7 +1854,7 @@ instance (FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum f g a) where
15441854-------------------------------------------------------------------------------
15451855
15461856instance FromJSON1 Seq.Seq where
1547− liftParseJSON p _ = withArray "Seq a" $
1857+ liftParseJSON p _ = withArray "Seq" $
15481858 fmap Seq.fromList .
15491859 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
15501860 {-# INLINE liftParseJSON #-}
@@ -1578,13 +1888,13 @@ instance FromJSON a => FromJSON (IntMap.IntMap a) where
15781888
15791889instance (FromJSONKey k, Ord k) => FromJSON1 (M.Map k) where
15801890 liftParseJSON p _ = case fromJSONKey of
1581− FromJSONKeyCoerce _-> withObject "Map k v" $
1891+ FromJSONKeyCoerce _ -> withObject "Map" $
15821892 fmap (H.foldrWithKey (M.insert . unsafeCoerce) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1583− FromJSONKeyText f -> withObject "Map k v" $
1893+ FromJSONKeyText f -> withObject "Map" $
15841894 fmap (H.foldrWithKey (M.insert . f) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1585− FromJSONKeyTextParser f -> withObject "Map k v" $
1895+ FromJSONKeyTextParser f -> withObject "Map" $
15861896 H.foldrWithKey (\k v m -> M.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure M.empty)
1587− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1897+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
15881898 fmap M.fromList . Tr.sequence .
15891899 zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
15901900 {-# INLINE liftParseJSON #-}
@@ -1612,18 +1922,18 @@ instance (FromJSON v) => FromJSON (Tree.Tree v) where
16121922
16131923instance FromJSON UUID.UUID where
16141924 parseJSON = withText "UUID" $
1615− maybe (fail "Invalid UUID") pure . UUID.fromText
1925+ maybe (fail "invalid UUID") pure . UUID.fromText
16161926
16171927instance FromJSONKey UUID.UUID where
16181928 fromJSONKey = FromJSONKeyTextParser $
1619− maybe (fail "Invalid UUID") pure . UUID.fromText
1929+ maybe (fail "invalid UUID") pure . UUID.fromText
16201930
16211931-------------------------------------------------------------------------------
16221932-- vector
16231933-------------------------------------------------------------------------------
16241934
16251935instance FromJSON1 Vector where
1626− liftParseJSON p _ = withArray "Vector a" $
1936+ liftParseJSON p _ = withArray "Vector" $
16271937 V.mapM (uncurry $ parseIndexedJSON p) . V.indexed
16281938 {-# INLINE liftParseJSON #-}
16291939
@@ -1637,14 +1947,14 @@ vectorParseJSON s = withArray s $ fmap V.convert . V.mapM (uncurry $ parseIndexe
16371947{-# INLINE vectorParseJSON #-}
16381948
16391949instance (Storable a, FromJSON a) => FromJSON (VS.Vector a) where
1640− parseJSON = vectorParseJSON "Data.Vector.Storable.Vector a"
1950+ parseJSON = vectorParseJSON "Data.Vector.Storable.Vector"
16411951
16421952instance (VP.Prim a, FromJSON a) => FromJSON (VP.Vector a) where
1643− parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector a"
1953+ parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector"
16441954 {-# INLINE parseJSON #-}
16451955
16461956instance (VG.Vector VU.Vector a, FromJSON a) => FromJSON (VU.Vector a) where
1647− parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector a"
1957+ parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector"
16481958 {-# INLINE parseJSON #-}
16491959
16501960-------------------------------------------------------------------------------
@@ -1658,13 +1968,13 @@ instance (Eq a, Hashable a, FromJSON a) => FromJSON (HashSet.HashSet a) where
16581968
16591969instance (FromJSONKey k, Eq k, Hashable k) => FromJSON1 (H.HashMap k) where
16601970 liftParseJSON p _ = case fromJSONKey of
1661− FromJSONKeyCoerce _ -> withObject "HashMap ~Text v" $
1971+ FromJSONKeyCoerce _ -> withObject "HashMap ~Text" $
16621972 uc . H.traverseWithKey (\k v -> p v <?> Key k)
1663− FromJSONKeyText f -> withObject "HashMap k v" $
1973+ FromJSONKeyText f -> withObject "HashMap" $
16641974 fmap (mapKey f) . H.traverseWithKey (\k v -> p v <?> Key k)
1665− FromJSONKeyTextParser f -> withObject "HashMap k v" $
1975+ FromJSONKeyTextParser f -> withObject "HashMap" $
16661976 H.foldrWithKey (\k v m -> H.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure H.empty)
1667− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1977+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
16681978 fmap H.fromList . Tr.sequence .
16691979 zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
16701980 where
@@ -1687,7 +1997,7 @@ instance FromJSON DotNetTime where
16871997 parseJSON = withText "DotNetTime" $ \t ->
16881998 let (s,m) = T.splitAt (T.length t - 5) t
16891999 t' = T.concat [s,".",m]
1690− in case parseTime defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
2000+ in case parseTimeM True defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
16912001 Just d -> pure (DotNetTime d)
16922002 _ -> fail "could not parse .NET time"
16932003 {-# INLINE parseJSON #-}
@@ -1696,7 +2006,6 @@ instance FromJSON DotNetTime where
16962006-- primitive
16972007-------------------------------------------------------------------------------
16982008
1699−#if MIN_VERSION_base(4,7,0)
17002009instance FromJSON a => FromJSON (PM.Array a) where
17012010 -- note: we could do better than this if vector exposed the data
17022011 -- constructor in Data.Vector.
@@ -1709,6 +2018,7 @@ instance FromJSON a => FromJSON (PM.SmallArray a) where
17092018instance (PM.Prim a,FromJSON a) => FromJSON (PM.PrimArray a) where
17102019 parseJSON = fmap Exts.fromList . parseJSON
17112020
2021+#if !MIN_VERSION_primitive(0,7,0)
17122022instance (PM.PrimUnlifted a,FromJSON a) => FromJSON (PM.UnliftedArray a) where
17132023 parseJSON = fmap Exts.fromList . parseJSON
17142024#endif
@@ -1781,6 +2091,40 @@ instance FromJSON DiffTime where
17812091 parseJSON = withBoundedScientific "DiffTime" $ pure . realToFrac
17822092 {-# INLINE parseJSON #-}
17832093
2094+instance FromJSON SystemTime where
2095+ parseJSON v = prependContext "SystemTime" $ do
2096+ n <- parseJSON v
2097+ let n' = floor (n * fromInteger (resolution n) :: Nano)
2098+ let (secs, nano) = n' `divMod` resolution n
2099+ return (MkSystemTime (fromInteger secs) (fromInteger nano))
2100+
2101+instance FromJSON CalendarDiffTime where
2102+ parseJSON = withObject "CalendarDiffTime" $ \obj -> CalendarDiffTime
2103+ <$> obj .: "months"
2104+ <*> obj .: "time"
2105+
2106+instance FromJSON CalendarDiffDays where
2107+ parseJSON = withObject "CalendarDiffDays" $ \obj -> CalendarDiffDays
2108+ <$> obj .: "months"
2109+ <*> obj .: "days"
2110+
2111+instance FromJSON DayOfWeek where
2112+ parseJSON = withText "DaysOfWeek" parseDayOfWeek
2113+
2114+parseDayOfWeek :: T.Text -> Parser DayOfWeek
2115+parseDayOfWeek t = case T.toLower t of
2116+ "monday" -> return Monday
2117+ "tuesday" -> return Tuesday
2118+ "wednesday" -> return Wednesday
2119+ "thursday" -> return Thursday
2120+ "friday" -> return Friday
2121+ "saturday" -> return Saturday
2122+ "sunday" -> return Sunday
2123+ _ -> fail "Invalid week day"
2124+
2125+instance FromJSONKey DayOfWeek where
2126+ fromJSONKey = FromJSONKeyTextParser parseDayOfWeek
2127+
17842128-------------------------------------------------------------------------------
17852129-- base Monoid/Semigroup
17862130-------------------------------------------------------------------------------
@@ -1901,14 +2245,15 @@ instance FromJSON a => FromJSON (Semigroup.Option a) where
19012245
19022246instance FromJSON1 Proxy where
19032247 {-# INLINE liftParseJSON #-}
1904− liftParseJSON _ _ Null = pure Proxy
1905− liftParseJSON _ _ v = typeMismatch "Proxy" v
2248+ liftParseJSON _ _ = fromNull "Proxy" Proxy
19062249
19072250instance FromJSON (Proxy a) where
19082251 {-# INLINE parseJSON #-}
1909− parseJSON Null = pure Proxy
1910− parseJSON v = typeMismatch "Proxy" v
2252+ parseJSON = fromNull "Proxy" Proxy
19112253
2254+fromNull :: String -> a -> Value -> Parser a
2255+fromNull _ a Null = pure a
2256+fromNull c _ v = prependContext c (typeMismatch "Null" v)
19122257
19132258instance FromJSON2 Tagged where
19142259 liftParseJSON2 _ _ p _ = fmap Tagged . p
@@ -1935,10 +2280,7 @@ instance (FromJSON a, FromJSON b, FromJSON c) => FromJSONKey (a,b,c)
19352280instance (FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSONKey (a,b,c,d)
19362281
19372282instance FromJSONKey Char where
1938− fromJSONKey = FromJSONKeyTextParser $ \t ->
1939− if T.length t == 1
1940− then return (T.index t 0)
1941− else typeMismatch "Expected Char but String didn't contain exactly one character" (String t)
2283+ fromJSONKey = FromJSONKeyTextParser parseChar
19422284 fromJSONKeyList = FromJSONKeyText T.unpack
19432285
19442286instance (FromJSONKey a, FromJSON a) => FromJSONKey [a] where