@@ -5,19 +5,16 @@
55{-# LANGUAGE FlexibleInstances #-}
66{-# LANGUAGE GADTs #-}
77{-# LANGUAGE MultiParamTypeClasses #-}
8−{-# LANGUAGE NamedFieldPuns #-}
8+{-# LANGUAGE NoImplicitPrelude #-}
99{-# LANGUAGE OverloadedStrings #-}
10+{-# LANGUAGE PolyKinds #-}
1011{-# LANGUAGE RecordWildCards #-}
1112{-# LANGUAGE ScopedTypeVariables #-}
1213{-# LANGUAGE TypeOperators #-}
13−{-# LANGUAGE TypeSynonymInstances #-}
14+{-# LANGUAGE TupleSections #-}
1415{-# LANGUAGE UndecidableInstances #-}
1516{-# LANGUAGE ViewPatterns #-}
1617
17−#if __GLASGOW_HASKELL__ >= 706
18−{-# LANGUAGE PolyKinds #-}
19−#endif
20−
2118#include "incoherent-compat.h"
2219#include "overlapping-compat.h"
2320
@@ -45,6 +42,9 @@ module Data.Aeson.Types.FromJSON
4542 , coerceFromJSONKeyFunction
4643 , mapFromJSONKeyFunction
4744
45+ , GFromJSONKey()
46+ , genericFromJSONKey
47+
4848 -- * List functions
4949 , listParser
5050
@@ -60,12 +60,14 @@ module Data.Aeson.Types.FromJSON
6060 , fromJSON
6161 , ifromJSON
6262 , typeMismatch
63+ , unexpected
6364 , parseField
6465 , parseFieldMaybe
6566 , parseFieldMaybe'
6667 , explicitParseField
6768 , explicitParseFieldMaybe
6869 , explicitParseFieldMaybe'
70+ , parseIndexedJSON
6971 -- ** Operators
7072 , (.:)
7173 , (.:?)
@@ -76,17 +78,16 @@ module Data.Aeson.Types.FromJSON
7678 , parseOptionalFieldWith
7779 ) where
7880
79−import Prelude ()
8081import Prelude.Compat
8182
82−import Control.Applicative ((<|>), Const(..))
83−import Control.Monad ((<=<), zipWithM)
83+import Control.Applicative ((<|>), Const(..), liftA2)
84+import Control.Monad (zipWithM)
8485import Data.Aeson.Internal.Functions (mapKey)
8586import Data.Aeson.Parser.Internal (eitherDecodeWith, jsonEOF)
8687import Data.Aeson.Types.Generic
8788import Data.Aeson.Types.Internal
8889import Data.Bits (unsafeShiftR)
89−import Data.Fixed (Fixed, HasResolution)
90+import Data.Fixed (Fixed, HasResolution (resolution), Nano)
9091import Data.Functor.Compose (Compose(..))
9192import Data.Functor.Identity (Identity(..))
9293import Data.Functor.Product (Product(..))
@@ -102,11 +103,14 @@ import Data.Scientific (Scientific, base10Exponent)
102103import Data.Tagged (Tagged(..))
103104import Data.Text (Text, pack, unpack)
104105import Data.Time (Day, DiffTime, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
105−import Data.Time.Format (parseTime)
106−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)
107110import Data.Traversable as Tr (sequence)
108111import Data.Vector (Vector)
109112import Data.Version (Version, parseVersion)
113+import Data.Void (Void)
110114import Data.Word (Word16, Word32, Word64, Word8)
111115import Foreign.Storable (Storable)
112116import Foreign.C.Types (CTime (..))
@@ -114,9 +118,9 @@ import GHC.Generics
114118import Numeric.Natural (Natural)
115119import Text.ParserCombinators.ReadP (readP_to_S)
116120import Unsafe.Coerce (unsafeCoerce)
117−import qualified Data.Aeson.Compat as Compat
118121import qualified Data.Aeson.Parser.Time as Time
119122import qualified Data.Attoparsec.ByteString.Char8 as A (endOfInput, parseOnly, scientific)
123+import qualified Data.ByteString.Lazy as L
120124import qualified Data.DList as DList
121125import qualified Data.HashMap.Strict as H
122126import qualified Data.HashSet as HashSet
@@ -139,18 +143,20 @@ import qualified Data.Vector.Primitive as VP
139143import qualified Data.Vector.Storable as VS
140144import qualified Data.Vector.Unboxed as VU
141145
142−#ifndef HAS_COERCIBLE
143−#define HAS_COERCIBLE (__GLASGOW_HASKELL__ >= 707)
146+import qualified GHC.Exts as Exts
147+import qualified Data.Primitive.Array as PM
148+import qualified Data.Primitive.SmallArray as PM
149+import qualified Data.Primitive.Types as PM
150+
151+#if MIN_VERSION_primitive(0,6,4)
152+#if !MIN_VERSION_primitive(0,7,0)
153+import qualified Data.Primitive.UnliftedArray as PM
144154#endif
155+import qualified Data.Primitive.PrimArray as PM
156+#endif
157+
145158
146−#if HAS_COERCIBLE
147159import Data.Coerce (Coercible, coerce)
148−coerce' :: Coercible a b => a -> b
149−coerce' = coerce
150−#else
151−coerce' :: a -> b
152−coerce' = unsafeCoerce
153−#endif
154160
155161parseIndexedJSON :: (Value -> Parser a) -> Int -> Value -> Parser a
156162parseIndexedJSON p idx value = p value <?> Index idx
@@ -159,7 +165,7 @@ parseIndexedJSON p idx value = p value <?> Index idx
159165parseIndexedJSONPair :: (Value -> Parser a) -> (Value -> Parser b) -> Int -> Value -> Parser (a, b)
160166parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
161167 where
162− p = withArray "(k,v)" $ \ab ->
168+ p = withArray "(k, v)" $ \ab ->
163169 let n = V.length ab
164170 in if n == 2
165171 then (,) <$> parseJSONElemAtIndex keyParser 0 ab
@@ -172,33 +178,33 @@ parseJSONElemAtIndex :: (Value -> Parser a) -> Int -> V.Vector Value -> Parser a
172178parseJSONElemAtIndex p idx ary = p (V.unsafeIndex ary idx) <?> Index idx
173179
174180parseRealFloat :: RealFloat a => String -> Value -> Parser a
175−parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
176−parseRealFloat _ Null = pure (0/0)
177−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)
178184{-# INLINE parseRealFloat #-}
179185
180−parseIntegralFromScientific :: forall a. Integral a => String -> Scientific -> Parser a
181−parseIntegralFromScientific expected s =
186+parseIntegralFromScientific :: forall a. Integral a => Scientific -> Parser a
187+parseIntegralFromScientific s =
182188 case Scientific.floatingOrInteger s :: Either Double a of
183189 Right x -> pure x
184− Left _ -> fail $ "expected " ++ expected ++ ", encountered floating number " ++ show s
190+ Left _ -> fail $ "unexpected floating number " ++ show s
185191{-# INLINE parseIntegralFromScientific #-}
186192
187193parseIntegral :: Integral a => String -> Value -> Parser a
188−parseIntegral expected =
189− withBoundedScientific expected $ parseIntegralFromScientific expected
194+parseIntegral name =
195+ prependContext name . withBoundedScientific' parseIntegralFromScientific
190196{-# INLINE parseIntegral #-}
191197
192−parseBoundedIntegralFromScientific :: (Bounded a, Integral a) => String -> Scientific -> Parser a
193−parseBoundedIntegralFromScientific expected s = maybe
194− (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)
195201 pure
196202 (Scientific.toBoundedInteger s)
197203{-# INLINE parseBoundedIntegralFromScientific #-}
198204
199205parseBoundedIntegral :: (Bounded a, Integral a) => String -> Value -> Parser a
200−parseBoundedIntegral expected =
201− withScientific expected $ parseBoundedIntegralFromScientific expected
206+parseBoundedIntegral name =
207+ prependContext name . withScientific' parseBoundedIntegralFromScientific
202208{-# INLINE parseBoundedIntegral #-}
203209
204210parseScientificText :: Text -> Parser Scientific
@@ -208,18 +214,20 @@ parseScientificText
208214 . T.encodeUtf8
209215
210216parseIntegralText :: Integral a => String -> Text -> Parser a
211−parseIntegralText expected t
212− = parseScientificText t
213− >>= rejectLargeExponent
214− >>= parseIntegralFromScientific expected
217+parseIntegralText name t =
218+ prependContext name $
219+ parseScientificText t
220+ >>= rejectLargeExponent
221+ >>= parseIntegralFromScientific
215222 where
216223 rejectLargeExponent :: Scientific -> Parser Scientific
217− rejectLargeExponent s = withBoundedScientific expected pure (Number s)
224+ rejectLargeExponent s = withBoundedScientific' pure (Number s)
218225{-# INLINE parseIntegralText #-}
219226
220227parseBoundedIntegralText :: (Bounded a, Integral a) => String -> Text -> Parser a
221−parseBoundedIntegralText expected t =
222− parseScientificText t >>= parseBoundedIntegralFromScientific expected
228+parseBoundedIntegralText name t =
229+ prependContext name $
230+ parseScientificText t >>= parseBoundedIntegralFromScientific
223231
224232parseOptionalFieldWith :: (Value -> Parser (Maybe a))
225233 -> Object -> Text -> Parser (Maybe a)
@@ -279,14 +287,21 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
279287--
280288-- The basic ways to signal a failed conversion are as follows:
281289--
282−-- * '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;
283292--
284−-- * '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 @('<|>')@;
285295--
286−-- * 'typeMismatch' produces an informative message for cases when the
287−-- 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.
288300--
289−-- 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':
290305--
291306-- @
292307-- \-- Allow ourselves to write 'Text' literals.
@@ -300,13 +315,15 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
300315-- '<*>' v '.:' \"y\"
301316--
302317-- \-- We do not expect a non-'Object' value here.
303−-- \-- We could use 'mzero' to fail, but 'typeMismatch'
318+-- \-- We could use 'Control.Applicative.empty' to fail, but 'typeMismatch'
304319-- \-- gives a much more informative error message.
305−-- 'parseJSON' invalid = 'typeMismatch' \"Coord\" invalid
320+-- 'parseJSON' invalid =
321+-- 'prependFailure' "parsing Coord failed, "
322+-- ('typeMismatch' \"Object\" invalid)
306323-- @
307324--
308325-- For this common case of only being concerned with a single
309−-- type of JSON value, the functions 'withObject', 'withNumber', etc.
326+-- type of JSON value, the functions 'withObject', 'withScientific', etc.
310327-- are provided. Their use is to be preferred when possible, since
311328-- they are more terse. Using 'withObject', we can rewrite the above instance
312329-- (assuming the same language extension and data type) as:
@@ -345,7 +362,7 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
345362-- @
346363--
347364-- The default implementation will be equivalent to
348−-- @parseJSON = 'genericParseJSON' 'defaultOptions'@; If you need different
365+-- @parseJSON = 'genericParseJSON' 'defaultOptions'@; if you need different
349366-- options, you can customize the generic decoding by defining:
350367--
351368-- @
@@ -363,13 +380,11 @@ class FromJSON a where
363380 parseJSON = genericParseJSON defaultOptions
364381
365382 parseJSONList :: Value -> Parser [a]
366− parseJSONList (Array a)
367− = zipWithM (parseIndexedJSON parseJSON) [0..]
383+ parseJSONList = withArray "[]" $ \a ->
384+ zipWithM (parseIndexedJSON parseJSON) [0..]
368385 . V.toList
369386 $ a
370387
371− parseJSONList v = typeMismatch "[a]" v
372−
373388-------------------------------------------------------------------------------
374389-- Classes and types for map keys
375390-------------------------------------------------------------------------------
@@ -381,6 +396,16 @@ class FromJSON a where
381396-- > newtype SomeId = SomeId { getSomeId :: Text }
382397-- > deriving (Eq,Ord,Hashable,FromJSONKey)
383398--
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+-- @
384409class FromJSONKey a where
385410 -- | Strategy for parsing the key of a map-like container.
386411 fromJSONKey :: FromJSONKeyFunction a
@@ -403,11 +428,7 @@ class FromJSONKey a where
403428-- At the moment this type is intentionally not exported. 'FromJSONKeyFunction'
404429-- can be inspected, but cannot be constructed.
405430data CoerceText a where
406−#if HAS_COERCIBLE
407431 CoerceText :: Coercible Text a => CoerceText a
408−#else
409− CoerceText :: CoerceText a
410−#endif
411432
412433-- | This type is related to 'ToJSONKeyFunction'. If 'FromJSONKeyValue' is used in the
413434-- 'FromJSONKey' instance, then 'ToJSONKeyValue' should be used in the 'ToJSONKey'
@@ -427,7 +448,7 @@ data FromJSONKeyFunction a
427448
428449-- | Only law abiding up to interpretation
429450instance Functor FromJSONKeyFunction where
430− fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce')
451+ fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce)
431452 fmap h (FromJSONKeyText f) = FromJSONKeyText (h . f)
432453 fmap h (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap h . f)
433454 fmap h (FromJSONKeyValue f) = FromJSONKeyValue (fmap h . f)
@@ -441,9 +462,7 @@ instance Functor FromJSONKeyFunction where
441462--
442463-- On pre GHC 7.8 this is unconstrainted function.
443464fromJSONKeyCoerce ::
444−#if HAS_COERCIBLE
445465 Coercible Text a =>
446−#endif
447466 FromJSONKeyFunction a
448467fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
449468
@@ -451,60 +470,91 @@ fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
451470--
452471-- See note on 'fromJSONKeyCoerce'.
453472coerceFromJSONKeyFunction ::
454−#if HAS_COERCIBLE
455473 Coercible a b =>
456−#endif
457474 FromJSONKeyFunction a -> FromJSONKeyFunction b
458−#if HAS_COERCIBLE
459475coerceFromJSONKeyFunction = coerce
460−#else
461−coerceFromJSONKeyFunction (FromJSONKeyCoerce CoerceText) = FromJSONKeyCoerce CoerceText
462−coerceFromJSONKeyFunction (FromJSONKeyText f) = FromJSONKeyText (coerce' . f)
463−coerceFromJSONKeyFunction (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap coerce' . f)
464−coerceFromJSONKeyFunction (FromJSONKeyValue f) = FromJSONKeyValue (fmap coerce' . f)
465−#endif
466476
467477{-# RULES
468478 "FromJSONKeyCoerce: fmap id" forall (x :: FromJSONKeyFunction a).
469479 fmap id x = x
470480 #-}
471−#if HAS_COERCIBLE
472481{-# RULES
473482 "FromJSONKeyCoerce: fmap coerce" forall x .
474483 fmap coerce x = coerceFromJSONKeyFunction x
475484 #-}
476−#endif
477485
478486-- | Same as 'fmap'. Provided for the consistency with 'ToJSONKeyFunction'.
479487mapFromJSONKeyFunction :: (a -> b) -> FromJSONKeyFunction a -> FromJSONKeyFunction b
480488mapFromJSONKeyFunction = fmap
481489
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+
482519-------------------------------------------------------------------------------
483520-- Functions needed for documentation
484521-------------------------------------------------------------------------------
485522
486523-- | Fail parsing due to a type mismatch, with a descriptive message.
487524--
488−-- Example usage:
525+-- The following wrappers should generally be prefered:
526+-- 'withObject', 'withArray', 'withText', 'withBool'.
489527--
490−-- @
491−-- instance FromJSON Coord where
492−-- parseJSON ('Object' v) = {- type matches, life is good -}
493−-- parseJSON wat = 'typeMismatch' \"Coord\" wat
494−-- @
495−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\"@).
496535 -> Value -- ^ The actual value encountered.
497536 -> Parser a
498537typeMismatch expected actual =
499− fail $ "expected " ++ expected ++ ", encountered " ++ name
500− where
501− name = case actual of
502− Object _ -> "Object"
503− Array _ -> "Array"
504− String _ -> "String"
505− Number _ -> "Number"
506− Bool _ -> "Boolean"
507− 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"
508558
509559-------------------------------------------------------------------------------
510560-- Lifings of FromJSON and ToJSON to unary and binary type constructors
@@ -585,9 +635,8 @@ class FromJSON2 f where
585635 -> (Value -> Parser b)
586636 -> (Value -> Parser [b])
587637 -> Value -> Parser [f a b]
588− liftParseJSONList2 fa ga fb gb v = case v of
589− Array vals -> fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
590− _ -> typeMismatch "[a]" v
638+ liftParseJSONList2 fa ga fb gb = withArray "[]" $ \vals ->
639+ fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
591640
592641-- | Lift the standard 'parseJSON' function through the type constructor.
593642parseJSON2 :: (FromJSON2 f, FromJSON a, FromJSON b) => Value -> Parser (f a b)
@@ -601,7 +650,7 @@ parseJSON2 = liftParseJSON2 parseJSON parseJSONList parseJSON parseJSONList
601650-- | Helper function to use with 'liftParseJSON'. See 'Data.Aeson.ToJSON.listEncoding'.
602651listParser :: (Value -> Parser a) -> Value -> Parser [a]
603652listParser f (Array xs) = fmap V.toList (V.mapM f xs)
604−listParser _ v = typeMismatch "[a]" v
653+listParser _ v = typeMismatch "Array" v
605654{-# INLINE listParser #-}
606655
607656-------------------------------------------------------------------------------
@@ -619,69 +668,137 @@ instance (FromJSON a) => FromJSON [a] where
619668-- Functions
620669-------------------------------------------------------------------------------
621670
622−-- | @'withObject' expected f value@ applies @f@ to the 'Object' when @value@
623−-- 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"
624686withObject :: String -> (Object -> Parser a) -> Value -> Parser a
625−withObject _ f (Object obj) = f obj
626−withObject expected _ v = typeMismatch expected v
687+withObject _ f (Object obj) = f obj
688+withObject name _ v = prependContext name (typeMismatch "Object" v)
627689{-# INLINE withObject #-}
628690
629−-- | @'withText' expected f value@ applies @f@ to the 'Text' when @value@ is a
630−-- '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"
631698withText :: String -> (Text -> Parser a) -> Value -> Parser a
632−withText _ f (String txt) = f txt
633−withText expected _ v = typeMismatch expected v
699+withText _ f (String txt) = f txt
700+withText name _ v = prependContext name (typeMismatch "String" v)
634701{-# INLINE withText #-}
635702
636703-- | @'withArray' expected f value@ applies @f@ to the 'Array' when @value@ is
637−-- 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"
638710withArray :: String -> (Array -> Parser a) -> Value -> Parser a
639−withArray _ f (Array arr) = f arr
640−withArray expected _ v = typeMismatch expected v
711+withArray _ f (Array arr) = f arr
712+withArray name _ v = prependContext name (typeMismatch "Array" v)
641713{-# INLINE withArray #-}
642714
643−-- | @'withScientific' expected f value@ applies @f@ to the 'Scientific' number
644−-- 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'
645717-- otherwise.
646−-- .
718+--
647719-- /Warning/: If you are converting from a scientific to an unbounded
648720-- type such as 'Integer' you may want to add a restriction on the
649721-- size of the exponent (see 'withBoundedScientific') to prevent
650722-- 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"
651728withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
652−withScientific _ f (Number scientific) = f scientific
653−withScientific expected _ v = typeMismatch expected v
729+withScientific _ f (Number scientific) = f scientific
730+withScientific name _ v = prependContext name (typeMismatch "Number" v)
654731{-# INLINE withScientific #-}
655732
656−-- | @'withBoundedScientific' expected f value@ applies @f@ to the 'Scientific' number
657−-- when @value@ is a 'Number' and fails using @'typeMismatch' expected@
658−-- 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.
659736--
660−-- The conversion will also fail wyth a @'typeMismatch' if the
661−-- '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.
662757withBoundedScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
663−withBoundedScientific _ f v@(Number scientific) =
664− if base10Exponent scientific > 1024
665− then typeMismatch "a number with exponent <= 1024" v
666− else f scientific
667−withBoundedScientific expected _ v = typeMismatch expected v
758+withBoundedScientific name f v = withBoundedScientific_ (prependContext name) f v
668759{-# INLINE withBoundedScientific #-}
669760
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+
670782-- | @'withBool' expected f value@ applies @f@ to the 'Bool' when @value@ is a
671−-- '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"
672789withBool :: String -> (Bool -> Parser a) -> Value -> Parser a
673−withBool _ f (Bool arr) = f arr
674−withBool expected _ v = typeMismatch expected v
790+withBool _ f (Bool arr) = f arr
791+withBool name _ v = prependContext name (typeMismatch "Boolean" v)
675792{-# INLINE withBool #-}
676793
677794-- | Decode a nested JSON-encoded string.
678795withEmbeddedJSON :: String -> (Value -> Parser a) -> Value -> Parser a
679796withEmbeddedJSON _ innerParser (String txt) =
680− either fail innerParser $ eitherDecode (Compat.fromStrict $ T.encodeUtf8 txt)
797+ either fail innerParser $ eitherDecode (L.fromStrict $ T.encodeUtf8 txt)
681798 where
682799 eitherDecode = eitherFormatError . eitherDecodeWith jsonEOF ifromJSON
683800 eitherFormatError = either (Left . uncurry formatError) Right
684−withEmbeddedJSON name _ v = typeMismatch name v
801+withEmbeddedJSON name _ v = prependContext name (typeMismatch "String" v)
685802{-# INLINE withEmbeddedJSON #-}
686803
687804-- | Convert a value from JSON, failing if the types do not match.
@@ -746,7 +863,7 @@ parseFieldMaybe' = (.:!)
746863-- E.g. @'explicitParseField' 'parseJSON1' :: ('FromJSON1' f, 'FromJSON' a) -> 'Object' -> 'Text' -> 'Parser' (f a)@
747864explicitParseField :: (Value -> Parser a) -> Object -> Text -> Parser a
748865explicitParseField p obj key = case H.lookup key obj of
749− Nothing -> fail $ "key " ++ show key ++ " not present"
866+ Nothing -> fail $ "key " ++ show key ++ " not found"
750867 Just v -> p v <?> Key key
751868{-# INLINE explicitParseField #-}
752869
@@ -786,11 +903,47 @@ pmval .!= val = fromMaybe val <$> pmval
786903-- Generic parseJSON
787904-------------------------------------------------------------------------------
788905
906+instance GFromJSON arity V1 where
907+ -- Whereof we cannot format, thereof we cannot parse:
908+ gParseJSON _ _ _ = fail "Attempted to parse empty type"
909+
910+
789911instance OVERLAPPABLE_ (GFromJSON arity a) => GFromJSON arity (M1 i c a) where
790912 -- Meta-information, which is not handled elsewhere, is just added to the
791913 -- parsed value:
792914 gParseJSON opts fargs = fmap M1 . gParseJSON opts fargs
793915
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+
794947instance (FromJSON a) => GFromJSON arity (K1 i a) where
795948 -- Constant values are decoded using their FromJSON instance:
796949 gParseJSON _opts _ = fmap K1 . parseJSON
@@ -805,342 +958,499 @@ instance (FromJSON1 f) => GFromJSON One (Rec1 f) where
805958 -- FromJSON1 instance:
806959 gParseJSON _opts (From1Args pj pjl) = fmap Rec1 . liftParseJSON pj pjl
807960
808−instance GFromJSON arity U1 where
809− -- Empty constructors are expected to be encoded as an empty array:
810− gParseJSON _opts _ v
811− | isEmptyArray v = pure U1
812− | 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+--------------------------------------------------------------------------------
970+
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
813978
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.
814987instance ( ConsFromJSON arity a
815988 , AllNullary (C1 c a) allNullary
816989 , ParseSum arity (C1 c a) allNullary
817− ) => GFromJSON arity (D1 d (C1 c a)) where
990+ , Constructor c
991+ ) => GFromJSON' arity (C1 c a) where
818992 -- The option 'tagSingleConstructors' determines whether to wrap
819993 -- a single-constructor type.
820− gParseJSON opts fargs
994+ gParseJSON' p@(_ :* opts :* _)
821995 | tagSingleConstructors opts
822− = fmap M1
823− . (unTagged :: Tagged allNullary (Parser (C1 c a p)) -> Parser (C1 c a p))
824− . parseSum opts fargs
825− | otherwise = fmap M1 . fmap M1 . consParseJSON opts fargs
826−
827−instance (ConsFromJSON arity a) => GFromJSON arity (C1 c a) where
828− -- Constructors need to be decoded differently depending on whether they're
829− -- a record or not. This distinction is made by consParseJSON:
830− gParseJSON opts fargs = fmap M1 . consParseJSON opts fargs
831−
832−instance ( FromProduct arity a, FromProduct arity b
833− , ProductSize a, ProductSize b
834− ) => GFromJSON arity (a :*: b) where
835− -- Products are expected to be encoded to an array. Here we check whether we
836− -- got an array of the same size as the product, then parse each of the
837− -- product's elements using parseProduct:
838− gParseJSON opts fargs = withArray "product (:*:)" $ \arr ->
839− let lenArray = V.length arr
840− lenProduct = (unTagged2 :: Tagged2 (a :*: b) Int -> Int)
841− productSize in
842− if lenArray == lenProduct
843− then parseProduct opts fargs arr 0 lenProduct
844− else fail $ "When expecting a product of " ++ show lenProduct ++
845− " values, encountered an Array of " ++ show lenArray ++
846− " elements instead"
847−
848−instance ( AllNullary (a :+: b) allNullary
849− , ParseSum arity (a :+: b) allNullary
850− ) => 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
8511006 -- If all constructors of a sum datatype are nullary and the
8521007 -- 'allNullaryToStringTag' option is set they are expected to be
8531008 -- encoded as strings. This distinction is made by 'parseSum':
854− gParseJSON opts fargs =
855− (unTagged :: Tagged allNullary (Parser ((a :+: b) d)) ->
856− Parser ((a :+: b) d))
857− . parseSum opts fargs
858−
859−instance (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) where
860− -- If an occurrence of the last type parameter is nested inside two
861− -- composed types, it is decoded by using the outermost type's FromJSON1
862− -- instance to generically decode the innermost type:
863− gParseJSON opts fargs =
864− let gpj = gParseJSON opts fargs in
865− 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
8661013
8671014--------------------------------------------------------------------------------
8681015
8691016class ParseSum arity f allNullary where
870− parseSum :: Options -> FromArgs arity a
871− -> Value -> Tagged allNullary (Parser (f a))
1017+ parseSum :: TypeName :* Options :* FromArgs arity a
1018+ -> Value
1019+ -> Tagged allNullary (Parser (f a))
8721020
873−instance ( SumFromString f
1021+instance ( ConstructorNames f
1022+ , SumFromString f
8741023 , FromPair arity f
8751024 , FromTaggedObject arity f
8761025 , FromUntaggedValue arity f
8771026 ) => ParseSum arity f True where
878− parseSum opts fargs
879− | allNullaryToStringTag opts = Tagged . parseAllNullarySum opts
880− | otherwise = Tagged . parseNonAllNullarySum opts fargs
1027+ parseSum p@(tname :* opts :* _)
1028+ | allNullaryToStringTag opts = Tagged . parseAllNullarySum tname opts
1029+ | otherwise = Tagged . parseNonAllNullarySum p
8811030
882−instance ( FromPair arity f
1031+instance ( ConstructorNames f
1032+ , FromPair arity f
8831033 , FromTaggedObject arity f
8841034 , FromUntaggedValue arity f
8851035 ) => ParseSum arity f False where
886− parseSum opts fargs = Tagged . parseNonAllNullarySum opts fargs
1036+ parseSum p = Tagged . parseNonAllNullarySum p
8871037
8881038--------------------------------------------------------------------------------
8891039
890−parseAllNullarySum :: SumFromString f => Options -> Value -> Parser (f a)
891−parseAllNullarySum opts = withText "Text" $ \key ->
892− maybe (notFound key) return $
893− 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])
8941062
8951063class SumFromString f where
896− parseSumFromString :: Options -> Text -> Maybe (f a)
1064+ parseSumFromString :: (String -> String) -> Text -> Maybe (f a)
8971065
8981066instance (SumFromString a, SumFromString b) => SumFromString (a :+: b) where
8991067 parseSumFromString opts key = (L1 <$> parseSumFromString opts key) <|>
9001068 (R1 <$> parseSumFromString opts key)
9011069
9021070instance (Constructor c) => SumFromString (C1 c U1) where
903− parseSumFromString opts key | key == name = Just $ M1 U1
904− | otherwise = Nothing
905− where
906− name = pack $ constructorTagModifier opts $
907− 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)
9081076
909−--------------------------------------------------------------------------------
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)
9101085
911−parseNonAllNullarySum :: ( FromPair arity f
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)
1104+
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
9121115 , FromTaggedObject arity f
9131116 , FromUntaggedValue arity f
914− ) => Options -> FromArgs arity c
1117+ , ConstructorNames f
1118+ ) => TypeName :* Options :* FromArgs arity c
9151119 -> Value -> Parser (f c)
916−parseNonAllNullarySum opts fargs =
1120+parseNonAllNullarySum p@(tname :* opts :* _) =
9171121 case sumEncoding opts of
9181122 TaggedObject{..} ->
919− withObject "Object" $ \obj -> do
920− tag <- obj .: pack tagFieldName
921− fromMaybe (notFound tag) $
922− 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])
9231133
9241134 ObjectWithSingleField ->
925− withObject "Object" $ \obj ->
926− case H.toList obj of
927− [pair@(tag, _)] -> fromMaybe (notFound tag) $
928− parsePair opts fargs pair
929− _ -> 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
9301145
9311146 TwoElemArray ->
932− withArray "Array" $ \arr ->
933− if V.length arr == 2
934− then case V.unsafeIndex arr 0 of
935− String tag -> fromMaybe (notFound tag) $
936− parsePair opts fargs (tag, V.unsafeIndex arr 1)
937− _ -> fail "First element is not a String"
938− 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
9391161
940− UntaggedValue -> parseUntaggedValue opts fargs
1162+ UntaggedValue -> parseUntaggedValue p
1163+ where
1164+ failWith_ = failWithCTags tname (constructorTagModifier opts)
9411165
9421166--------------------------------------------------------------------------------
9431167
9441168class FromTaggedObject arity f where
945− parseFromTaggedObject :: Options -> FromArgs arity a
946− -> String -> Object
947− -> 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))
9481175
9491176instance ( FromTaggedObject arity a, FromTaggedObject arity b) =>
9501177 FromTaggedObject arity (a :+: b) where
951− parseFromTaggedObject opts fargs contentsFieldName obj tag =
952− (fmap L1 <$> parseFromTaggedObject opts fargs contentsFieldName obj tag) <|>
953− (fmap R1 <$> parseFromTaggedObject opts fargs contentsFieldName obj tag)
1178+ parseFromTaggedObject p obj =
1179+ (fmap L1 <$> parseFromTaggedObject p obj) <|>
1180+ (fmap R1 <$> parseFromTaggedObject p obj)
9541181
955−instance ( FromTaggedObject' arity f
1182+instance ( IsRecord f isRecord
1183+ , FromTaggedObject' arity f isRecord
9561184 , Constructor c
9571185 ) => FromTaggedObject arity (C1 c f) where
958− parseFromTaggedObject opts fargs contentsFieldName obj tag
959− | tag == name = Just $ M1 <$> parseFromTaggedObject'
960− opts fargs contentsFieldName obj
961− | otherwise = Nothing
962− where
963− name = pack $ constructorTagModifier opts $
964− 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)
9651195
9661196--------------------------------------------------------------------------------
9671197
968−class FromTaggedObject' arity f where
969− parseFromTaggedObject' :: Options -> FromArgs arity a -> String
970− -> Object -> Parser (f a)
971−
972−class FromTaggedObject'' arity f isRecord where
973− parseFromTaggedObject'' :: Options -> FromArgs arity a -> String
974− -> Object -> Tagged isRecord (Parser (f a))
975−
976−instance ( IsRecord f isRecord
977− , FromTaggedObject'' arity f isRecord
978− ) => FromTaggedObject' arity f where
979− parseFromTaggedObject' opts fargs contentsFieldName =
980− (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a)) .
981− parseFromTaggedObject'' opts fargs contentsFieldName
982−
983−instance (FromRecord arity f) => FromTaggedObject'' arity f True where
984− parseFromTaggedObject'' opts fargs _ =
985− Tagged . parseRecord opts fargs
986−
987−instance (GFromJSON arity f) => FromTaggedObject'' arity f False where
988− parseFromTaggedObject'' opts fargs contentsFieldName = Tagged .
989− (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
9901216
991−instance OVERLAPPING_ FromTaggedObject'' arity U1 False where
992− 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)
9931220
9941221--------------------------------------------------------------------------------
9951222
1223+-- | Constructors need to be decoded differently depending on whether they're
1224+-- a record or not. This distinction is made by 'ConsParseJSON'.
9961225class ConsFromJSON arity f where
997− consParseJSON :: Options -> FromArgs arity a
998− -> Value -> Parser (f a)
1226+ consParseJSON
1227+ :: ConName :* TypeName :* Options :* FromArgs arity a
1228+ -> Value -> Parser (f a)
9991229
10001230class ConsFromJSON' arity f isRecord where
1001− consParseJSON' :: Options -> FromArgs arity a
1002− -> Value -> Tagged isRecord (Parser (f a))
1231+ consParseJSON'
1232+ :: ConName :* TypeName :* Options :* FromArgs arity a
1233+ -> Value -> Tagged isRecord (Parser (f a))
10031234
10041235instance ( IsRecord f isRecord
10051236 , ConsFromJSON' arity f isRecord
10061237 ) => ConsFromJSON arity f where
1007− consParseJSON opts fargs =
1238+ consParseJSON p =
10081239 (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
1009− . consParseJSON' opts fargs
1240+ . consParseJSON' p
10101241
10111242instance OVERLAPPING_
1012− ( GFromJSON arity a, FromRecord arity (S1 s a)
1243+ ( GFromJSON arity a, RecordFromJSON arity (S1 s a)
10131244 ) => ConsFromJSON' arity (S1 s a) True where
1014− consParseJSON' opts fargs
1015− | unwrapUnaryRecords opts = Tagged . gParseJSON opts fargs
1016− | 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))
10171248
1018−instance FromRecord arity f => ConsFromJSON' arity f True where
1019− consParseJSON' opts fargs =
1020− 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))
10211252
1022−instance GFromJSON arity f => ConsFromJSON' arity f False where
1023− 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
10241274
10251275--------------------------------------------------------------------------------
10261276
1027−class FromRecord arity f where
1028− parseRecord :: Options -> FromArgs arity a
1029− -> Object -> Parser (f a)
1277+class FieldNames f where
1278+ fieldNames :: f a -> [Text] -> [Text]
10301279
1031−instance ( FromRecord arity a
1032− , FromRecord arity b
1033− ) => FromRecord arity (a :*: b) where
1034− parseRecord opts fargs obj =
1035− (:*:) <$> parseRecord opts fargs obj
1036− <*> 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)
10371284
1038−instance OVERLAPPABLE_ (Selector s, GFromJSON arity a) =>
1039− FromRecord arity (S1 s a) where
1040− parseRecord opts fargs =
1041− (<?> 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
10421298 where
1043− 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)
10441331
10451332instance INCOHERENT_ (Selector s, FromJSON a) =>
1046− FromRecord arity (S1 s (K1 i (Maybe a))) where
1047− parseRecord opts _ obj = M1 . K1 <$> obj .:? pack label
1048− where
1049− label = fieldLabelModifier opts $
1050− 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 <$> obj .:? pack label
1335+ where
1336+ label = fieldLabelModifier opts sname
1337+ sname = selName (undefined :: M1 _i s _f _p)
10511338
10521339-- Parse an Option like a Maybe.
10531340instance INCOHERENT_ (Selector s, FromJSON a) =>
1054− FromRecord arity (S1 s (K1 i (Semigroup.Option a))) where
1055− parseRecord opts fargs obj = wrap <$> parseRecord opts fargs obj
1341+ RecordFromJSON' arity (S1 s (K1 i (Semigroup.Option a))) where
1342+ recordParseJSON' p obj = wrap <$> recordParseJSON' p obj
10561343 where
10571344 wrap :: S1 s (K1 i (Maybe a)) p -> S1 s (K1 i (Semigroup.Option a)) p
10581345 wrap (M1 (K1 a)) = M1 (K1 (Semigroup.Option a))
10591346
10601347--------------------------------------------------------------------------------
10611348
1062−class FromProduct arity f where
1063− 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
10641371 -> Array -> Int -> Int
10651372 -> Parser (f a)
10661373
1067−instance ( FromProduct arity a
1068− , FromProduct arity b
1069− ) => FromProduct arity (a :*: b) where
1070− parseProduct opts fargs arr ix len =
1071− (:*:) <$> parseProduct opts fargs arr ix lenL
1072− <*> parseProduct opts fargs arr ixR lenR
1374+instance ( ProductFromJSON arity a
1375+ , ProductFromJSON arity b
1376+ ) => ProductFromJSON arity (a :*: b) where
1377+ productParseJSON p arr ix len =
1378+ (:*:) <$> productParseJSON p arr ix lenL
1379+ <*> productParseJSON p arr ixR lenR
10731380 where
10741381 lenL = len `unsafeShiftR` 1
10751382 ixR = ix + lenL
10761383 lenR = len - lenL
10771384
1078−instance (GFromJSON arity a) => FromProduct arity (S1 s a) where
1079− parseProduct opts fargs arr ix _ =
1080− 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 <$> gParseJSON opts fargs (V.unsafeIndex arr ix) <?> Index ix
10811388
10821389--------------------------------------------------------------------------------
10831390
10841391class FromPair arity f where
1085− parsePair :: Options -> FromArgs arity a
1086− -> Pair -> Maybe (Parser (f a))
1392+ -- The first component of the parameter tuple is the tag to match.
1393+ parsePair :: Text :* TypeName :* Options :* FromArgs arity a
1394+ -> Value
1395+ -> Maybe (Parser (f a))
10871396
10881397instance ( FromPair arity a
10891398 , FromPair arity b
10901399 ) => FromPair arity (a :+: b) where
1091− parsePair opts fargs pair = (fmap L1 <$> parsePair opts fargs pair) <|>
1092− (fmap R1 <$> parsePair opts fargs pair)
1400+ parsePair p pair =
1401+ (fmap L1 <$> parsePair p pair) <|>
1402+ (fmap R1 <$> parsePair p pair)
10931403
10941404instance ( Constructor c
1095− , GFromJSON arity a
10961405 , ConsFromJSON arity a
10971406 ) => FromPair arity (C1 c a) where
1098− parsePair opts fargs (tag, value)
1099− | tag == tag' = Just $ gParseJSON opts fargs value
1407+ parsePair (tag :* p@(_ :* opts :* _)) v
1408+ | tag == tag' = Just $ M1 <$> consParseJSON (cname :* p) v
11001409 | otherwise = Nothing
1101− where
1102− tag' = pack $ constructorTagModifier opts $
1103− conName (undefined :: t c a p)
1410+ where
1411+ tag' = pack $ constructorTagModifier opts cname
1412+ cname = conName (undefined :: M1 _i c _a _p)
11041413
11051414--------------------------------------------------------------------------------
11061415
11071416class FromUntaggedValue arity f where
1108− parseUntaggedValue :: Options -> FromArgs arity a
1109− -> Value -> Parser (f a)
1417+ parseUntaggedValue :: TypeName :* Options :* FromArgs arity a
1418+ -> Value
1419+ -> Parser (f a)
11101420
11111421instance
11121422 ( FromUntaggedValue arity a
11131423 , FromUntaggedValue arity b
11141424 ) => FromUntaggedValue arity (a :+: b)
11151425 where
1116− parseUntaggedValue opts fargs value =
1117− L1 <$> parseUntaggedValue opts fargs value <|>
1118− R1 <$> parseUntaggedValue opts fargs value
1426+ parseUntaggedValue p value =
1427+ L1 <$> parseUntaggedValue p value <|>
1428+ R1 <$> parseUntaggedValue p value
11191429
11201430instance OVERLAPPABLE_
1121− ( GFromJSON arity a
1122− , ConsFromJSON arity a
1431+ ( ConsFromJSON arity a
1432+ , Constructor c
11231433 ) => FromUntaggedValue arity (C1 c a)
11241434 where
1125− parseUntaggedValue = gParseJSON
1435+ parseUntaggedValue p = fmap M1 . consParseJSON (cname :* p)
1436+ where
1437+ cname = conName (undefined :: M1 _i c _f _p)
11261438
11271439instance OVERLAPPING_
11281440 ( Constructor c )
11291441 => FromUntaggedValue arity (C1 c U1)
11301442 where
1131− parseUntaggedValue opts _ (String s)
1132− | s == pack (constructorTagModifier opts (conName (undefined :: t c U1 p))) =
1133− pure $ M1 U1
1134− | otherwise =
1135− fail $ "Invalid tag: " ++ unpack s
1136− parseUntaggedValue _ _ v = typeMismatch (conName (undefined :: t c U1 p)) v
1137−
1138−
1139−--------------------------------------------------------------------------------
1140−
1141−notFound :: Text -> Parser a
1142−notFound key = fail $ "The key \"" ++ unpack key ++ "\" was not found"
1143−{-# 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
11441454
11451455-------------------------------------------------------------------------------
11461456-- Instances
@@ -1198,17 +1508,20 @@ instance (FromJSON a, FromJSON b) => FromJSON (Either a b) where
11981508 parseJSON = parseJSON2
11991509 {-# INLINE parseJSON #-}
12001510
1201−
1511+instance FromJSON Void where
1512+ parseJSON _ = fail "Cannot parse Void"
1513+ {-# INLINE parseJSON #-}
12021514
12031515instance FromJSON Bool where
1204− parseJSON = withBool "Bool" pure
1516+ parseJSON (Bool b) = pure b
1517+ parseJSON v = typeMismatch "Bool" v
12051518 {-# INLINE parseJSON #-}
12061519
12071520instance FromJSONKey Bool where
12081521 fromJSONKey = FromJSONKeyTextParser $ \t -> case t of
12091522 "true" -> pure True
12101523 "false" -> pure False
1211− _ -> fail $ "Cannot parse key into Bool: " ++ T.unpack t
1524+ _ -> fail $ "cannot parse key " ++ show t ++ " into Bool"
12121525
12131526instance FromJSON Ordering where
12141527 parseJSON = withText "Ordering" $ \s ->
@@ -1216,25 +1529,30 @@ instance FromJSON Ordering where
12161529 "LT" -> return LT
12171530 "EQ" -> return EQ
12181531 "GT" -> return GT
1219− _ -> fail "Parsing Ordering value failed: expected \"LT\", \"EQ\", or \"GT\""
1532+ _ -> fail $ "parsing Ordering failed, unexpected " ++ show s ++
1533+ " (expected \"LT\", \"EQ\", or \"GT\")"
12201534
12211535instance FromJSON () where
12221536 parseJSON = withArray "()" $ \v ->
12231537 if V.null v
12241538 then pure ()
1225− else fail "Expected an empty array"
1539+ else prependContext "()" $ fail "expected an empty array"
12261540 {-# INLINE parseJSON #-}
12271541
12281542instance FromJSON Char where
1229− parseJSON = withText "Char" $ \t ->
1230− if T.compareLength t 1 == EQ
1231− then pure $ T.head t
1232− else fail "Expected a string of length 1"
1543+ parseJSON = withText "Char" parseChar
12331544 {-# INLINE parseJSON #-}
12341545
1235− parseJSONList = withText "String" $ pure . T.unpack
1546+ parseJSONList (String s) = pure (T.unpack s)
1547+ parseJSONList v = typeMismatch "String" v
12361548 {-# INLINE parseJSONList #-}
12371549
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+
12381556instance FromJSON Double where
12391557 parseJSON = parseRealFloat "Double"
12401558 {-# INLINE parseJSON #-}
@@ -1258,12 +1576,22 @@ instance FromJSONKey Float where
12581576 _ -> Scientific.toRealFloat <$> parseScientificText t
12591577
12601578instance (FromJSON a, Integral a) => FromJSON (Ratio a) where
1261− parseJSON = withObject "Rational" $ \obj -> do
1262− numerator <- obj .: "numerator"
1263− denominator <- obj .: "denominator"
1264− if denominator == 0
1265− then fail "Ratio denominator was 0"
1266− 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
12671595 {-# INLINE parseJSON #-}
12681596
12691597-- | This instance includes a bounds check to prevent maliciously
@@ -1271,7 +1599,7 @@ instance (FromJSON a, Integral a) => FromJSON (Ratio a) where
12711599-- newtype 'Scientific' and provide your own instance using
12721600-- 'withScientific' if you want to allow larger inputs.
12731601instance HasResolution a => FromJSON (Fixed a) where
1274− parseJSON = withBoundedScientific "Fixed" $ pure . realToFrac
1602+ parseJSON = prependContext "Fixed" . withBoundedScientific' (pure . realToFrac)
12751603 {-# INLINE parseJSON #-}
12761604
12771605instance FromJSON Int where
@@ -1294,19 +1622,20 @@ instance FromJSONKey Integer where
12941622
12951623instance FromJSON Natural where
12961624 parseJSON value = do
1297− integer :: Integer <- parseIntegral "Natural" value
1298− if integer < 0 then
1299− fail $ "expected Natural, encountered negative number " <> show integer
1300− else
1301− pure $ fromIntegral integer
1625+ integer <- parseIntegral "Natural" value
1626+ parseNatural integer
13021627
13031628instance FromJSONKey Natural where
13041629 fromJSONKey = FromJSONKeyTextParser $ \text -> do
1305− integer :: Integer <- parseIntegralText "Natural" text
1306− if integer < 0 then
1307− fail $ "expected Natural, encountered negative number " <> show integer
1308− else
1309− 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
13101639
13111640instance FromJSON Int8 where
13121641 parseJSON = parseBoundedIntegral "Int8"
@@ -1403,17 +1732,17 @@ parseVersionText = go . readP_to_S parseVersion . unpack
14031732 where
14041733 go [(v,[])] = return v
14051734 go (_ : xs) = go xs
1406− go _ = fail "could not parse Version"
1735+ go _ = fail "parsing Version failed"
14071736
14081737-------------------------------------------------------------------------------
14091738-- semigroups NonEmpty
14101739-------------------------------------------------------------------------------
14111740
14121741instance FromJSON1 NonEmpty where
1413− liftParseJSON p _ = withArray "NonEmpty a" $
1742+ liftParseJSON p _ = withArray "NonEmpty" $
14141743 (>>= ne) . Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
14151744 where
1416− ne [] = fail "Expected a NonEmpty but got an empty list"
1745+ ne [] = fail "parsing NonEmpty failed, unexpected empty list"
14171746 ne (x:xs) = pure (x :| xs)
14181747 {-# INLINE liftParseJSON #-}
14191748
@@ -1434,7 +1763,7 @@ instance FromJSON Scientific where
14341763-------------------------------------------------------------------------------
14351764
14361765instance FromJSON1 DList.DList where
1437− liftParseJSON p _ = withArray "DList a" $
1766+ liftParseJSON p _ = withArray "DList" $
14381767 fmap DList.fromList .
14391768 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
14401769 {-# INLINE liftParseJSON #-}
@@ -1511,7 +1840,7 @@ instance (FromJSON1 f, FromJSON1 g) => FromJSON1 (Sum f g) where
15111840 inr = "InR"
15121841
15131842 liftParseJSON _ _ _ = fail $
1514− "expected an object with a single property " ++
1843+ "parsing Sum failed, expected an object with a single property " ++
15151844 "where the property key should be either " ++
15161845 "\"InL\" or \"InR\""
15171846 {-# INLINE liftParseJSON #-}
@@ -1525,7 +1854,7 @@ instance (FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum f g a) where
15251854-------------------------------------------------------------------------------
15261855
15271856instance FromJSON1 Seq.Seq where
1528− liftParseJSON p _ = withArray "Seq a" $
1857+ liftParseJSON p _ = withArray "Seq" $
15291858 fmap Seq.fromList .
15301859 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
15311860 {-# INLINE liftParseJSON #-}
@@ -1559,13 +1888,13 @@ instance FromJSON a => FromJSON (IntMap.IntMap a) where
15591888
15601889instance (FromJSONKey k, Ord k) => FromJSON1 (M.Map k) where
15611890 liftParseJSON p _ = case fromJSONKey of
1562− FromJSONKeyCoerce _-> withObject "Map k v" $
1891+ FromJSONKeyCoerce _ -> withObject "Map" $
15631892 fmap (H.foldrWithKey (M.insert . unsafeCoerce) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1564− FromJSONKeyText f -> withObject "Map k v" $
1893+ FromJSONKeyText f -> withObject "Map" $
15651894 fmap (H.foldrWithKey (M.insert . f) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1566− FromJSONKeyTextParser f -> withObject "Map k v" $
1895+ FromJSONKeyTextParser f -> withObject "Map" $
15671896 H.foldrWithKey (\k v m -> M.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure M.empty)
1568− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1897+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
15691898 fmap M.fromList . Tr.sequence .
15701899 zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
15711900 {-# INLINE liftParseJSON #-}
@@ -1593,18 +1922,18 @@ instance (FromJSON v) => FromJSON (Tree.Tree v) where
15931922
15941923instance FromJSON UUID.UUID where
15951924 parseJSON = withText "UUID" $
1596− maybe (fail "Invalid UUID") pure . UUID.fromText
1925+ maybe (fail "invalid UUID") pure . UUID.fromText
15971926
15981927instance FromJSONKey UUID.UUID where
15991928 fromJSONKey = FromJSONKeyTextParser $
1600− maybe (fail "Invalid UUID") pure . UUID.fromText
1929+ maybe (fail "invalid UUID") pure . UUID.fromText
16011930
16021931-------------------------------------------------------------------------------
16031932-- vector
16041933-------------------------------------------------------------------------------
16051934
16061935instance FromJSON1 Vector where
1607− liftParseJSON p _ = withArray "Vector a" $
1936+ liftParseJSON p _ = withArray "Vector" $
16081937 V.mapM (uncurry $ parseIndexedJSON p) . V.indexed
16091938 {-# INLINE liftParseJSON #-}
16101939
@@ -1618,14 +1947,14 @@ vectorParseJSON s = withArray s $ fmap V.convert . V.mapM (uncurry $ parseIndexe
16181947{-# INLINE vectorParseJSON #-}
16191948
16201949instance (Storable a, FromJSON a) => FromJSON (VS.Vector a) where
1621− parseJSON = vectorParseJSON "Data.Vector.Storable.Vector a"
1950+ parseJSON = vectorParseJSON "Data.Vector.Storable.Vector"
16221951
16231952instance (VP.Prim a, FromJSON a) => FromJSON (VP.Vector a) where
1624− parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector a"
1953+ parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector"
16251954 {-# INLINE parseJSON #-}
16261955
16271956instance (VG.Vector VU.Vector a, FromJSON a) => FromJSON (VU.Vector a) where
1628− parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector a"
1957+ parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector"
16291958 {-# INLINE parseJSON #-}
16301959
16311960-------------------------------------------------------------------------------
@@ -1639,13 +1968,13 @@ instance (Eq a, Hashable a, FromJSON a) => FromJSON (HashSet.HashSet a) where
16391968
16401969instance (FromJSONKey k, Eq k, Hashable k) => FromJSON1 (H.HashMap k) where
16411970 liftParseJSON p _ = case fromJSONKey of
1642− FromJSONKeyCoerce _ -> withObject "HashMap ~Text v" $
1971+ FromJSONKeyCoerce _ -> withObject "HashMap ~Text" $
16431972 uc . H.traverseWithKey (\k v -> p v <?> Key k)
1644− FromJSONKeyText f -> withObject "HashMap k v" $
1973+ FromJSONKeyText f -> withObject "HashMap" $
16451974 fmap (mapKey f) . H.traverseWithKey (\k v -> p v <?> Key k)
1646− FromJSONKeyTextParser f -> withObject "HashMap k v" $
1975+ FromJSONKeyTextParser f -> withObject "HashMap" $
16471976 H.foldrWithKey (\k v m -> H.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure H.empty)
1648− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1977+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
16491978 fmap H.fromList . Tr.sequence .
16501979 zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
16511980 where
@@ -1668,11 +1997,33 @@ instance FromJSON DotNetTime where
16681997 parseJSON = withText "DotNetTime" $ \t ->
16691998 let (s,m) = T.splitAt (T.length t - 5) t
16701999 t' = T.concat [s,".",m]
1671− in case parseTime defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
2000+ in case parseTimeM True defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
16722001 Just d -> pure (DotNetTime d)
16732002 _ -> fail "could not parse .NET time"
16742003 {-# INLINE parseJSON #-}
16752004
2005+-------------------------------------------------------------------------------
2006+-- primitive
2007+-------------------------------------------------------------------------------
2008+
2009+instance FromJSON a => FromJSON (PM.Array a) where
2010+ -- note: we could do better than this if vector exposed the data
2011+ -- constructor in Data.Vector.
2012+ parseJSON = fmap Exts.fromList . parseJSON
2013+
2014+instance FromJSON a => FromJSON (PM.SmallArray a) where
2015+ parseJSON = fmap Exts.fromList . parseJSON
2016+
2017+#if MIN_VERSION_primitive(0,6,4)
2018+instance (PM.Prim a,FromJSON a) => FromJSON (PM.PrimArray a) where
2019+ parseJSON = fmap Exts.fromList . parseJSON
2020+
2021+#if !MIN_VERSION_primitive(0,7,0)
2022+instance (PM.PrimUnlifted a,FromJSON a) => FromJSON (PM.UnliftedArray a) where
2023+ parseJSON = fmap Exts.fromList . parseJSON
2024+#endif
2025+#endif
2026+
16762027-------------------------------------------------------------------------------
16772028-- time
16782029-------------------------------------------------------------------------------
@@ -1740,6 +2091,40 @@ instance FromJSON DiffTime where
17402091 parseJSON = withBoundedScientific "DiffTime" $ pure . realToFrac
17412092 {-# INLINE parseJSON #-}
17422093
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+
17432128-------------------------------------------------------------------------------
17442129-- base Monoid/Semigroup
17452130-------------------------------------------------------------------------------
@@ -1860,14 +2245,15 @@ instance FromJSON a => FromJSON (Semigroup.Option a) where
18602245
18612246instance FromJSON1 Proxy where
18622247 {-# INLINE liftParseJSON #-}
1863− liftParseJSON _ _ Null = pure Proxy
1864− liftParseJSON _ _ v = typeMismatch "Proxy" v
2248+ liftParseJSON _ _ = fromNull "Proxy" Proxy
18652249
18662250instance FromJSON (Proxy a) where
18672251 {-# INLINE parseJSON #-}
1868− parseJSON Null = pure Proxy
1869− parseJSON v = typeMismatch "Proxy" v
2252+ parseJSON = fromNull "Proxy" Proxy
18702253
2254+fromNull :: String -> a -> Value -> Parser a
2255+fromNull _ a Null = pure a
2256+fromNull c _ v = prependContext c (typeMismatch "Null" v)
18712257
18722258instance FromJSON2 Tagged where
18732259 liftParseJSON2 _ _ p _ = fmap Tagged . p
@@ -1894,10 +2280,7 @@ instance (FromJSON a, FromJSON b, FromJSON c) => FromJSONKey (a,b,c)
18942280instance (FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSONKey (a,b,c,d)
18952281
18962282instance FromJSONKey Char where
1897− fromJSONKey = FromJSONKeyTextParser $ \t ->
1898− if T.length t == 1
1899− then return (T.index t 0)
1900− else typeMismatch "Expected Char but String didn't contain exactly one character" (String t)
2283+ fromJSONKey = FromJSONKeyTextParser parseChar
19012284 fromJSONKeyList = FromJSONKeyText T.unpack
19022285
19032286instance (FromJSONKey a, FromJSON a) => FromJSONKey [a] where