@@ -5,19 +5,17 @@
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−
18+#include "incoherent-compat.h"
2119#include "overlapping-compat.h"
2220
2321-- TODO: Drop this when we remove support for Data.Attoparsec.Number
@@ -44,6 +42,9 @@ module Data.Aeson.Types.FromJSON
4442 , coerceFromJSONKeyFunction
4543 , mapFromJSONKeyFunction
4644
45+ , GFromJSONKey()
46+ , genericFromJSONKey
47+
4748 -- * List functions
4849 , listParser
4950
@@ -51,34 +52,42 @@ module Data.Aeson.Types.FromJSON
5152 , withObject
5253 , withText
5354 , withArray
54− , withNumber
5555 , withScientific
5656 , withBool
57+ , withEmbeddedJSON
5758
5859 -- * Functions
5960 , fromJSON
6061 , ifromJSON
62+ , typeMismatch
63+ , unexpected
64+ , parseField
65+ , parseFieldMaybe
66+ , parseFieldMaybe'
67+ , explicitParseField
68+ , explicitParseFieldMaybe
69+ , explicitParseFieldMaybe'
70+ , parseIndexedJSON
71+ -- ** Operators
6172 , (.:)
6273 , (.:?)
6374 , (.:!)
6475 , (.!=)
65− , typeMismatch
6676
6777 -- * Internal
6878 , parseOptionalFieldWith
6979 ) where
7080
71−import Prelude ()
7281import Prelude.Compat
7382
74−import Control.Applicative ((<|>), Const(..))
75−import Control.Monad ((<=<), zipWithM)
83+import Control.Applicative ((<|>), Const(..), liftA2)
84+import Control.Monad (zipWithM)
7685import Data.Aeson.Internal.Functions (mapKey)
86+import Data.Aeson.Parser.Internal (eitherDecodeWith, jsonEOF)
7787import Data.Aeson.Types.Generic
7888import Data.Aeson.Types.Internal
79−import Data.Attoparsec.Number (Number(..))
8089import Data.Bits (unsafeShiftR)
81−import Data.Fixed (Fixed, HasResolution)
90+import Data.Fixed (Fixed, HasResolution (resolution), Nano)
8291import Data.Functor.Compose (Compose(..))
8392import Data.Functor.Identity (Identity(..))
8493import Data.Functor.Product (Product(..))
@@ -87,57 +96,67 @@ import Data.Hashable (Hashable(..))
8796import Data.Int (Int16, Int32, Int64, Int8)
8897import Data.List.NonEmpty (NonEmpty(..))
8998import Data.Maybe (fromMaybe)
90−import Data.Monoid ((<>), Dual(..), First (..), Last (..))
99+import Data.Semigroup ((<>))
91100import Data.Proxy (Proxy(..))
92101import Data.Ratio ((%), Ratio)
93−import Data.Scientific (Scientific)
102+import Data.Scientific (Scientific, base10Exponent)
94103import Data.Tagged (Tagged(..))
95104import Data.Text (Text, pack, unpack)
96−import Data.Time (Day, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
97−import Data.Time.Format (parseTime)
98−import Data.Time.Locale.Compat (defaultTimeLocale)
105+import Data.Time (Day, DiffTime, LocalTime, NominalDiffTime, TimeOfDay, UTCTime, ZonedTime)
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)
99110import Data.Traversable as Tr (sequence)
100111import Data.Vector (Vector)
101112import Data.Version (Version, parseVersion)
113+import Data.Void (Void)
102114import Data.Word (Word16, Word32, Word64, Word8)
103115import Foreign.Storable (Storable)
116+import Foreign.C.Types (CTime (..))
104117import GHC.Generics
105118import Numeric.Natural (Natural)
106119import Text.ParserCombinators.ReadP (readP_to_S)
120+import Unsafe.Coerce (unsafeCoerce)
107121import qualified Data.Aeson.Parser.Time as Time
108122import qualified Data.Attoparsec.ByteString.Char8 as A (endOfInput, parseOnly, scientific)
123+import qualified Data.ByteString.Lazy as L
109124import qualified Data.DList as DList
110125import qualified Data.HashMap.Strict as H
111126import qualified Data.HashSet as HashSet
112127import qualified Data.IntMap as IntMap
113128import qualified Data.IntSet as IntSet
114129import qualified Data.Map as M
130+import qualified Data.Monoid as Monoid
115131import qualified Data.Scientific as Scientific
132+import qualified Data.Semigroup as Semigroup
116133import qualified Data.Sequence as Seq
117134import qualified Data.Set as Set
118135import qualified Data.Text as T
119136import qualified Data.Text.Encoding as T
120137import qualified Data.Text.Lazy as LT
121138import qualified Data.Tree as Tree
139+import qualified Data.UUID.Types as UUID
122140import qualified Data.Vector as V
123141import qualified Data.Vector.Generic as VG
124142import qualified Data.Vector.Primitive as VP
125143import qualified Data.Vector.Storable as VS
126144import qualified Data.Vector.Unboxed as VU
127−import Unsafe.Coerce (unsafeCoerce)
128145
129−#ifndef HAS_COERCIBLE
130−#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
154+#endif
155+import qualified Data.Primitive.PrimArray as PM
131156#endif
132157
133−#if HAS_COERCIBLE
158+
134159import Data.Coerce (Coercible, coerce)
135−coerce' :: Coercible a b => a -> b
136−coerce' = coerce
137−#else
138−coerce' :: a -> b
139−coerce' = unsafeCoerce
140−#endif
141160
142161parseIndexedJSON :: (Value -> Parser a) -> Int -> Value -> Parser a
143162parseIndexedJSON p idx value = p value <?> Index idx
@@ -146,7 +165,7 @@ parseIndexedJSON p idx value = p value <?> Index idx
146165parseIndexedJSONPair :: (Value -> Parser a) -> (Value -> Parser b) -> Int -> Value -> Parser (a, b)
147166parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
148167 where
149− p = withArray "(k,v)" $ \ab ->
168+ p = withArray "(k, v)" $ \ab ->
150169 let n = V.length ab
151170 in if n == 2
152171 then (,) <$> parseJSONElemAtIndex keyParser 0 ab
@@ -158,43 +177,34 @@ parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
158177parseJSONElemAtIndex :: (Value -> Parser a) -> Int -> V.Vector Value -> Parser a
159178parseJSONElemAtIndex p idx ary = p (V.unsafeIndex ary idx) <?> Index idx
160179
161−scientificToNumber :: Scientific -> Number
162−scientificToNumber s
163− | e < 0 = D $ Scientific.toRealFloat s
164− | otherwise = I $ c * 10 ^ e
165− where
166− e = Scientific.base10Exponent s
167− c = Scientific.coefficient s
168−{-# INLINE scientificToNumber #-}
169−
170180parseRealFloat :: RealFloat a => String -> Value -> Parser a
171−parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
172−parseRealFloat _ Null = pure (0/0)
173−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)
174184{-# INLINE parseRealFloat #-}
175185
176−parseIntegralFromScientific :: forall a. Integral a => String -> Scientific -> Parser a
177−parseIntegralFromScientific expected s =
186+parseIntegralFromScientific :: forall a. Integral a => Scientific -> Parser a
187+parseIntegralFromScientific s =
178188 case Scientific.floatingOrInteger s :: Either Double a of
179189 Right x -> pure x
180− Left _ -> fail $ "Floating number specified for " ++ expected ++ ": " ++ show s
190+ Left _ -> fail $ "unexpected floating number " ++ show s
181191{-# INLINE parseIntegralFromScientific #-}
182192
183193parseIntegral :: Integral a => String -> Value -> Parser a
184−parseIntegral expected =
185− withScientific expected $ parseIntegralFromScientific expected
194+parseIntegral name =
195+ prependContext name . withBoundedScientific' parseIntegralFromScientific
186196{-# INLINE parseIntegral #-}
187197
188−parseBoundedIntegralFromScientific :: (Bounded a, Integral a) => String -> Scientific -> Parser a
189−parseBoundedIntegralFromScientific expected s = maybe
190− (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)
191201 pure
192202 (Scientific.toBoundedInteger s)
193203{-# INLINE parseBoundedIntegralFromScientific #-}
194204
195205parseBoundedIntegral :: (Bounded a, Integral a) => String -> Value -> Parser a
196−parseBoundedIntegral expected =
197− withScientific expected $ parseBoundedIntegralFromScientific expected
206+parseBoundedIntegral name =
207+ prependContext name . withScientific' parseBoundedIntegralFromScientific
198208{-# INLINE parseBoundedIntegral #-}
199209
200210parseScientificText :: Text -> Parser Scientific
@@ -204,13 +214,20 @@ parseScientificText
204214 . T.encodeUtf8
205215
206216parseIntegralText :: Integral a => String -> Text -> Parser a
207−parseIntegralText expected t =
208− parseScientificText t >>= parseIntegralFromScientific expected
217+parseIntegralText name t =
218+ prependContext name $
219+ parseScientificText t
220+ >>= rejectLargeExponent
221+ >>= parseIntegralFromScientific
222+ where
223+ rejectLargeExponent :: Scientific -> Parser Scientific
224+ rejectLargeExponent s = withBoundedScientific' pure (Number s)
209225{-# INLINE parseIntegralText #-}
210226
211227parseBoundedIntegralText :: (Bounded a, Integral a) => String -> Text -> Parser a
212−parseBoundedIntegralText expected t =
213− parseScientificText t >>= parseBoundedIntegralFromScientific expected
228+parseBoundedIntegralText name t =
229+ prependContext name $
230+ parseScientificText t >>= parseBoundedIntegralFromScientific
214231
215232parseOptionalFieldWith :: (Value -> Parser (Maybe a))
216233 -> Object -> Text -> Parser (Maybe a)
@@ -270,14 +287,21 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
270287--
271288-- The basic ways to signal a failed conversion are as follows:
272289--
273−-- * '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;
292+--
293+-- * 'Control.Applicative.empty' (or 'Control.Monad.mzero') is uninformative:
294+-- use it when the error is meant to be caught by some @('<|>')@;
274295--
275−-- * 'fail' yields a custom error message
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.
276300--
277−-- * 'typeMismatch' produces an informative message for cases when the
278−-- value encountered is not of the expected type
301+-- 'prependFailure' (or 'modifyFailure') add more information to a parser's
302+-- error messages.
279303--
280−-- An example type and instance:
304+-- An example type and instance using 'typeMismatch' and 'prependFailure':
281305--
282306-- @
283307-- \-- Allow ourselves to write 'Text' literals.
@@ -285,15 +309,30 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
285309--
286310-- data Coord = Coord { x :: Double, y :: Double }
287311--
288−-- instance FromJSON Coord where
289−-- parseJSON ('Object' v) = Coord '<$>'
290−-- v '.:' \"x\" '<*>'
291−-- v '.:' \"y\"
312+-- instance 'FromJSON' Coord where
313+-- 'parseJSON' ('Object' v) = Coord
314+-- '<$>' v '.:' \"x\"
315+-- '<*>' v '.:' \"y\"
292316--
293−-- \-- We do not expect a non-'Object' value here.
294−-- \-- We could use 'mzero' to fail, but 'typeMismatch'
295−-- \-- gives a much more informative error message.
296−-- parseJSON invalid = 'typeMismatch' \"Coord\" invalid
317+-- \-- We do not expect a non-'Object' value here.
318+-- \-- We could use 'Control.Applicative.empty' to fail, but 'typeMismatch'
319+-- \-- gives a much more informative error message.
320+-- 'parseJSON' invalid =
321+-- 'prependFailure' "parsing Coord failed, "
322+-- ('typeMismatch' \"Object\" invalid)
323+-- @
324+--
325+-- For this common case of only being concerned with a single
326+-- type of JSON value, the functions 'withObject', 'withScientific', etc.
327+-- are provided. Their use is to be preferred when possible, since
328+-- they are more terse. Using 'withObject', we can rewrite the above instance
329+-- (assuming the same language extension and data type) as:
330+--
331+-- @
332+-- instance 'FromJSON' Coord where
333+-- 'parseJSON' = 'withObject' \"Coord\" $ \\v -> Coord
334+-- '<$>' v '.:' \"x\"
335+-- '<*>' v '.:' \"y\"
297336-- @
298337--
299338-- Instead of manually writing your 'FromJSON' instance, there are two options
@@ -301,7 +340,7 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
301340--
302341-- * "Data.Aeson.TH" provides Template Haskell functions which will derive an
303342-- instance at compile time. The generated instance is optimized for your type
304−-- so will probably be more efficient than the following two options:
343+-- so it will probably be more efficient than the following option.
305344--
306345-- * The compiler can provide a default generic implementation for
307346-- 'parseJSON'.
@@ -319,18 +358,21 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
319358--
320359-- data Coord = Coord { x :: Double, y :: Double } deriving 'Generic'
321360--
322−-- instance FromJSON Coord
361+-- instance 'FromJSON' Coord
323362-- @
324363--
325−-- If @DefaultSignatures@ doesn't give exactly the results you want,
326−-- you can customize the generic decoding with only a tiny amount of
327−-- effort, using 'genericParseJSON' with your preferred 'Options':
364+-- The default implementation will be equivalent to
365+-- @parseJSON = 'genericParseJSON' 'defaultOptions'@; if you need different
366+-- options, you can customize the generic decoding by defining:
328367--
329368-- @
330−-- instance FromJSON Coord where
331−-- parseJSON = 'genericParseJSON' 'defaultOptions'
369+-- customOptions = 'defaultOptions'
370+-- { 'fieldLabelModifier' = 'map' 'Data.Char.toUpper'
371+-- }
372+--
373+-- instance 'FromJSON' Coord where
374+-- 'parseJSON' = 'genericParseJSON' customOptions
332375-- @
333−
334376class FromJSON a where
335377 parseJSON :: Value -> Parser a
336378
@@ -338,13 +380,11 @@ class FromJSON a where
338380 parseJSON = genericParseJSON defaultOptions
339381
340382 parseJSONList :: Value -> Parser [a]
341− parseJSONList (Array a)
342− = zipWithM (parseIndexedJSON parseJSON) [0..]
383+ parseJSONList = withArray "[]" $ \a ->
384+ zipWithM (parseIndexedJSON parseJSON) [0..]
343385 . V.toList
344386 $ a
345387
346− parseJSONList v = typeMismatch "[a]" v
347−
348388-------------------------------------------------------------------------------
349389-- Classes and types for map keys
350390-------------------------------------------------------------------------------
@@ -356,6 +396,16 @@ class FromJSON a where
356396-- > newtype SomeId = SomeId { getSomeId :: Text }
357397-- > deriving (Eq,Ord,Hashable,FromJSONKey)
358398--
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+-- @
359409class FromJSONKey a where
360410 -- | Strategy for parsing the key of a map-like container.
361411 fromJSONKey :: FromJSONKeyFunction a
@@ -378,11 +428,7 @@ class FromJSONKey a where
378428-- At the moment this type is intentionally not exported. 'FromJSONKeyFunction'
379429-- can be inspected, but cannot be constructed.
380430data CoerceText a where
381−#if HAS_COERCIBLE
382431 CoerceText :: Coercible Text a => CoerceText a
383−#else
384− CoerceText :: CoerceText a
385−#endif
386432
387433-- | This type is related to 'ToJSONKeyFunction'. If 'FromJSONKeyValue' is used in the
388434-- 'FromJSONKey' instance, then 'ToJSONKeyValue' should be used in the 'ToJSONKey'
@@ -402,7 +448,7 @@ data FromJSONKeyFunction a
402448
403449-- | Only law abiding up to interpretation
404450instance Functor FromJSONKeyFunction where
405− fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce')
451+ fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce)
406452 fmap h (FromJSONKeyText f) = FromJSONKeyText (h . f)
407453 fmap h (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap h . f)
408454 fmap h (FromJSONKeyValue f) = FromJSONKeyValue (fmap h . f)
@@ -416,9 +462,7 @@ instance Functor FromJSONKeyFunction where
416462--
417463-- On pre GHC 7.8 this is unconstrainted function.
418464fromJSONKeyCoerce ::
419−#if HAS_COERCIBLE
420465 Coercible Text a =>
421−#endif
422466 FromJSONKeyFunction a
423467fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
424468
@@ -426,60 +470,91 @@ fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
426470--
427471-- See note on 'fromJSONKeyCoerce'.
428472coerceFromJSONKeyFunction ::
429−#if HAS_COERCIBLE
430473 Coercible a b =>
431−#endif
432474 FromJSONKeyFunction a -> FromJSONKeyFunction b
433−#if HAS_COERCIBLE
434475coerceFromJSONKeyFunction = coerce
435−#else
436−coerceFromJSONKeyFunction (FromJSONKeyCoerce CoerceText) = FromJSONKeyCoerce CoerceText
437−coerceFromJSONKeyFunction (FromJSONKeyText f) = FromJSONKeyText (coerce' . f)
438−coerceFromJSONKeyFunction (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap coerce' . f)
439−coerceFromJSONKeyFunction (FromJSONKeyValue f) = FromJSONKeyValue (fmap coerce' . f)
440−#endif
441476
442477{-# RULES
443478 "FromJSONKeyCoerce: fmap id" forall (x :: FromJSONKeyFunction a).
444479 fmap id x = x
445480 #-}
446−#if HAS_COERCIBLE
447481{-# RULES
448482 "FromJSONKeyCoerce: fmap coerce" forall x .
449483 fmap coerce x = coerceFromJSONKeyFunction x
450484 #-}
451−#endif
452485
453486-- | Same as 'fmap'. Provided for the consistency with 'ToJSONKeyFunction'.
454487mapFromJSONKeyFunction :: (a -> b) -> FromJSONKeyFunction a -> FromJSONKeyFunction b
455488mapFromJSONKeyFunction = fmap
456489
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+
457519-------------------------------------------------------------------------------
458520-- Functions needed for documentation
459521-------------------------------------------------------------------------------
460522
461523-- | Fail parsing due to a type mismatch, with a descriptive message.
462524--
463−-- Example usage:
525+-- The following wrappers should generally be prefered:
526+-- 'withObject', 'withArray', 'withText', 'withBool'.
464527--
465−-- @
466−-- instance FromJSON Coord where
467−-- parseJSON ('Object' v) = {- type matches, life is good -}
468−-- parseJSON wat = 'typeMismatch' \"Coord\" wat
469−-- @
470−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\"@).
471535 -> Value -- ^ The actual value encountered.
472536 -> Parser a
473537typeMismatch expected actual =
474− fail $ "expected " ++ expected ++ ", encountered " ++ name
475− where
476− name = case actual of
477− Object _ -> "Object"
478− Array _ -> "Array"
479− String _ -> "String"
480− Number _ -> "Number"
481− Bool _ -> "Boolean"
482− 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"
483558
484559-------------------------------------------------------------------------------
485560-- Lifings of FromJSON and ToJSON to unary and binary type constructors
@@ -492,7 +567,7 @@ typeMismatch expected actual =
492567--
493568-- * "Data.Aeson.TH" provides Template Haskell functions which will derive an
494569-- instance at compile time. The generated instance is optimized for your type
495−-- so will probably be more efficient than the following two options:
570+-- so it will probably be more efficient than the following option.
496571--
497572-- * The compiler can provide a default generic implementation for
498573-- 'liftParseJSON'.
@@ -510,16 +585,20 @@ typeMismatch expected actual =
510585--
511586-- data Pair a b = Pair { pairFst :: a, pairSnd :: b } deriving 'Generic1'
512587--
513−-- instance FromJSON a => FromJSON1 (Pair a)
588+-- instance 'FromJSON' a => 'FromJSON1' (Pair a)
514589-- @
515590--
516−-- If @DefaultSignatures@ doesn't give exactly the results you want,
591+-- If the default implementation doesn't give exactly the results you want,
517592-- you can customize the generic decoding with only a tiny amount of
518593-- effort, using 'genericLiftParseJSON' with your preferred 'Options':
519594--
520595-- @
521−-- instance FromJSON a => FromJSON1 (Pair a) where
522−-- liftParseJSON = 'genericLiftParseJSON' 'defaultOptions'
596+-- customOptions = 'defaultOptions'
597+-- { 'fieldLabelModifier' = 'map' 'Data.Char.toUpper'
598+-- }
599+--
600+-- instance 'FromJSON' a => 'FromJSON1' (Pair a) where
601+-- 'liftParseJSON' = 'genericLiftParseJSON' customOptions
523602-- @
524603class FromJSON1 f where
525604 liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (f a)
@@ -556,9 +635,8 @@ class FromJSON2 f where
556635 -> (Value -> Parser b)
557636 -> (Value -> Parser [b])
558637 -> Value -> Parser [f a b]
559− liftParseJSONList2 fa ga fb gb v = case v of
560− Array vals -> fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
561− _ -> typeMismatch "[a]" v
638+ liftParseJSONList2 fa ga fb gb = withArray "[]" $ \vals ->
639+ fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
562640
563641-- | Lift the standard 'parseJSON' function through the type constructor.
564642parseJSON2 :: (FromJSON2 f, FromJSON a, FromJSON b) => Value -> Parser (f a b)
@@ -572,7 +650,7 @@ parseJSON2 = liftParseJSON2 parseJSON parseJSONList parseJSON parseJSONList
572650-- | Helper function to use with 'liftParseJSON'. See 'Data.Aeson.ToJSON.listEncoding'.
573651listParser :: (Value -> Parser a) -> Value -> Parser [a]
574652listParser f (Array xs) = fmap V.toList (V.mapM f xs)
575−listParser _ v = typeMismatch "[a]" v
653+listParser _ v = typeMismatch "Array" v
576654{-# INLINE listParser #-}
577655
578656-------------------------------------------------------------------------------
@@ -590,48 +668,139 @@ instance (FromJSON a) => FromJSON [a] where
590668-- Functions
591669-------------------------------------------------------------------------------
592670
593−-- | @withObject expected f value@ applies @f@ to the 'Object' when @value@ is an @Object@
594−-- 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"
595686withObject :: String -> (Object -> Parser a) -> Value -> Parser a
596−withObject _ f (Object obj) = f obj
597−withObject expected _ v = typeMismatch expected v
687+withObject _ f (Object obj) = f obj
688+withObject name _ v = prependContext name (typeMismatch "Object" v)
598689{-# INLINE withObject #-}
599690
600−-- | @withText expected f value@ applies @f@ to the 'Text' when @value@ is a @String@
601−-- 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"
602698withText :: String -> (Text -> Parser a) -> Value -> Parser a
603−withText _ f (String txt) = f txt
604−withText expected _ v = typeMismatch expected v
699+withText _ f (String txt) = f txt
700+withText name _ v = prependContext name (typeMismatch "String" v)
605701{-# INLINE withText #-}
606702
607−-- | @withArray expected f value@ applies @f@ to the 'Array' when @value@ is an @Array@
608−-- and fails using @'typeMismatch' expected@ otherwise.
703+-- | @'withArray' expected f value@ applies @f@ to the 'Array' when @value@ is
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"
609710withArray :: String -> (Array -> Parser a) -> Value -> Parser a
610−withArray _ f (Array arr) = f arr
611−withArray expected _ v = typeMismatch expected v
711+withArray _ f (Array arr) = f arr
712+withArray name _ v = prependContext name (typeMismatch "Array" v)
612713{-# INLINE withArray #-}
613714
614−-- | @withNumber expected f value@ applies @f@ to the 'Number' when @value@ is a 'Number'.
615−-- and fails using @'typeMismatch' expected@ otherwise.
616−withNumber :: String -> (Number -> Parser a) -> Value -> Parser a
617−withNumber expected f = withScientific expected (f . scientificToNumber)
618−{-# INLINE withNumber #-}
619−{-# DEPRECATED withNumber "Use withScientific instead" #-}
620−
621−-- | @withScientific expected f value@ applies @f@ to the 'Scientific' number when @value@ is a 'Number'.
622−-- and fails using @'typeMismatch' expected@ otherwise.
715+-- | @'withScientific' name f value@ applies @f@ to the 'Scientific' number
716+-- when @value@ is a 'Data.Aeson.Number' and fails using 'typeMismatch'
717+-- otherwise.
718+--
719+-- /Warning/: If you are converting from a scientific to an unbounded
720+-- type such as 'Integer' you may want to add a restriction on the
721+-- size of the exponent (see 'withBoundedScientific') to prevent
722+-- 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"
623728withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
624−withScientific _ f (Number scientific) = f scientific
625−withScientific expected _ v = typeMismatch expected v
729+withScientific _ f (Number scientific) = f scientific
730+withScientific name _ v = prependContext name (typeMismatch "Number" v)
626731{-# INLINE withScientific #-}
627732
628−-- | @withBool expected f value@ applies @f@ to the 'Bool' when @value@ is a @Bool@
629−-- and fails using @'typeMismatch' expected@ 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.
736+--
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.
757+withBoundedScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
758+withBoundedScientific name f v = withBoundedScientific_ (prependContext name) f v
759+{-# INLINE withBoundedScientific #-}
760+
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+
782+-- | @'withBool' expected f value@ applies @f@ to the 'Bool' when @value@ is a
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"
630789withBool :: String -> (Bool -> Parser a) -> Value -> Parser a
631−withBool _ f (Bool arr) = f arr
632−withBool expected _ v = typeMismatch expected v
790+withBool _ f (Bool arr) = f arr
791+withBool name _ v = prependContext name (typeMismatch "Boolean" v)
633792{-# INLINE withBool #-}
634793
794+-- | Decode a nested JSON-encoded string.
795+withEmbeddedJSON :: String -> (Value -> Parser a) -> Value -> Parser a
796+withEmbeddedJSON _ innerParser (String txt) =
797+ either fail innerParser $ eitherDecode (L.fromStrict $ T.encodeUtf8 txt)
798+ where
799+ eitherDecode = eitherFormatError . eitherDecodeWith jsonEOF ifromJSON
800+ eitherFormatError = either (Left . uncurry formatError) Right
801+withEmbeddedJSON name _ v = prependContext name (typeMismatch "String" v)
802+{-# INLINE withEmbeddedJSON #-}
803+
635804-- | Convert a value from JSON, failing if the types do not match.
636805fromJSON :: (FromJSON a) => Value -> Result a
637806fromJSON = parse parseJSON
@@ -650,32 +819,68 @@ ifromJSON = iparse parseJSON
650819-- in an object for it to be valid. If the key and value are
651820-- optional, use '.:?' instead.
652821(.:) :: (FromJSON a) => Object -> Text -> Parser a
653−obj .: key = case H.lookup key obj of
654− Nothing -> fail $ "key " ++ show key ++ " not present"
655− Just v -> parseJSON v <?> Key key
822+(.:) = explicitParseField parseJSON
656823{-# INLINE (.:) #-}
657824
658−-- | Retrieve the value associated with the given key of an 'Object'. The
659−-- result is 'Nothing' if the key is not present or value is 'Null', or 'empty'
660−-- if the value cannot be converted to the desired type.
825+-- | Retrieve the value associated with the given key of an 'Object'. The
826+-- result is 'Nothing' if the key is not present or if its value is 'Null',
827+-- or 'empty' if the value cannot be converted to the desired type.
661828--
662829-- This accessor is most useful if the key and value can be absent
663830-- from an object without affecting its validity. If the key and
664831-- value are mandatory, use '.:' instead.
665832(.:?) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
666−obj .:? key = case H.lookup key obj of
667− Nothing -> pure Nothing
668− Just v -> parseJSON v <?> Key key
833+(.:?) = explicitParseFieldMaybe parseJSON
669834{-# INLINE (.:?) #-}
670835
671−-- | Like '.:?', but the resulting parser will fail,
672−-- if the key is present but is 'Null'.
836+-- | Retrieve the value associated with the given key of an 'Object'.
837+-- The result is 'Nothing' if the key is not present or 'empty' if the
838+-- value cannot be converted to the desired type.
839+--
840+-- This differs from '.:?' by attempting to parse 'Null' the same as any
841+-- other JSON value, instead of interpreting it as 'Nothing'.
673842(.:!) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
674−obj .:! key = case H.lookup key obj of
675− Nothing -> pure Nothing
676− Just v -> Just <$> parseJSON v <?> Key key
843+(.:!) = explicitParseFieldMaybe' parseJSON
677844{-# INLINE (.:!) #-}
678845
846+-- | Function variant of '.:'.
847+parseField :: (FromJSON a) => Object -> Text -> Parser a
848+parseField = (.:)
849+{-# INLINE parseField #-}
850+
851+-- | Function variant of '.:?'.
852+parseFieldMaybe :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
853+parseFieldMaybe = (.:?)
854+{-# INLINE parseFieldMaybe #-}
855+
856+-- | Function variant of '.:!'.
857+parseFieldMaybe' :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
858+parseFieldMaybe' = (.:!)
859+{-# INLINE parseFieldMaybe' #-}
860+
861+-- | Variant of '.:' with explicit parser function.
862+--
863+-- E.g. @'explicitParseField' 'parseJSON1' :: ('FromJSON1' f, 'FromJSON' a) -> 'Object' -> 'Text' -> 'Parser' (f a)@
864+explicitParseField :: (Value -> Parser a) -> Object -> Text -> Parser a
865+explicitParseField p obj key = case H.lookup key obj of
866+ Nothing -> fail $ "key " ++ show key ++ " not found"
867+ Just v -> p v <?> Key key
868+{-# INLINE explicitParseField #-}
869+
870+-- | Variant of '.:?' with explicit parser function.
871+explicitParseFieldMaybe :: (Value -> Parser a) -> Object -> Text -> Parser (Maybe a)
872+explicitParseFieldMaybe p obj key = case H.lookup key obj of
873+ Nothing -> pure Nothing
874+ Just v -> liftParseJSON p (listParser p) v <?> Key key -- listParser isn't used by maybe instance.
875+{-# INLINE explicitParseFieldMaybe #-}
876+
877+-- | Variant of '.:!' with explicit parser function.
878+explicitParseFieldMaybe' :: (Value -> Parser a) -> Object -> Text -> Parser (Maybe a)
879+explicitParseFieldMaybe' p obj key = case H.lookup key obj of
880+ Nothing -> pure Nothing
881+ Just v -> Just <$> p v <?> Key key
882+{-# INLINE explicitParseFieldMaybe' #-}
883+
679884-- | Helper for use in combination with '.:?' to provide default
680885-- values for optional JSON object fields.
681886--
@@ -698,11 +903,47 @@ pmval .!= val = fromMaybe val <$> pmval
698903-- Generic parseJSON
699904-------------------------------------------------------------------------------
700905
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+
701911instance OVERLAPPABLE_ (GFromJSON arity a) => GFromJSON arity (M1 i c a) where
702912 -- Meta-information, which is not handled elsewhere, is just added to the
703913 -- parsed value:
704914 gParseJSON opts fargs = fmap M1 . gParseJSON opts fargs
705915
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+
706947instance (FromJSON a) => GFromJSON arity (K1 i a) where
707948 -- Constant values are decoded using their FromJSON instance:
708949 gParseJSON _opts _ = fmap K1 . parseJSON
@@ -717,327 +958,499 @@ instance (FromJSON1 f) => GFromJSON One (Rec1 f) where
717958 -- FromJSON1 instance:
718959 gParseJSON _opts (From1Args pj pjl) = fmap Rec1 . liftParseJSON pj pjl
719960
720−instance GFromJSON arity U1 where
721− -- Empty constructors are expected to be encoded as an empty array:
722− gParseJSON _opts _ v
723− | isEmptyArray v = pure U1
724− | otherwise = typeMismatch "unit constructor (U1)" v
725−
726−instance (ConsFromJSON arity a) => GFromJSON arity (C1 c a) where
727− -- Constructors need to be decoded differently depending on whether they're
728− -- a record or not. This distinction is made by consParseJSON:
729− gParseJSON opts fargs = fmap M1 . consParseJSON opts fargs
730−
731−instance ( FromProduct arity a, FromProduct arity b
732− , ProductSize a, ProductSize b
733− ) => GFromJSON arity (a :*: b) where
734− -- Products are expected to be encoded to an array. Here we check whether we
735− -- got an array of the same size as the product, then parse each of the
736− -- product's elements using parseProduct:
737− gParseJSON opts fargs = withArray "product (:*:)" $ \arr ->
738− let lenArray = V.length arr
739− lenProduct = (unTagged2 :: Tagged2 (a :*: b) Int -> Int)
740− productSize in
741− if lenArray == lenProduct
742− then parseProduct opts fargs arr 0 lenProduct
743− else fail $ "When expecting a product of " ++ show lenProduct ++
744− " values, encountered an Array of " ++ show lenArray ++
745− " elements instead"
746−
747−instance ( AllNullary (a :+: b) allNullary
748− , ParseSum arity (a :+: b) allNullary
749− ) => GFromJSON arity (a :+: b) where
750− -- If all constructors of a sum datatype are nullary and the
751− -- 'allNullaryToStringTag' option is set they are expected to be
752− -- encoded as strings. This distinction is made by 'parseSum':
753− gParseJSON opts fargs =
754− (unTagged :: Tagged allNullary (Parser ((a :+: b) d)) ->
755− Parser ((a :+: b) d))
756− . parseSum opts fargs
757−
758961instance (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) where
759962 -- If an occurrence of the last type parameter is nested inside two
760963 -- composed types, it is decoded by using the outermost type's FromJSON1
761964 -- instance to generically decode the innermost type:
762965 gParseJSON opts fargs =
763− let gpj = gParseJSON opts fargs in
764− fmap Comp1 . liftParseJSON gpj (listParser gpj)
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
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.
987+instance ( ConsFromJSON arity a
988+ , AllNullary (C1 c a) allNullary
989+ , ParseSum arity (C1 c a) allNullary
990+ , Constructor c
991+ ) => GFromJSON' arity (C1 c a) where
992+ -- The option 'tagSingleConstructors' determines whether to wrap
993+ -- a single-constructor type.
994+ gParseJSON' p@(_ :* opts :* _)
995+ | tagSingleConstructors opts
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
1006+ -- If all constructors of a sum datatype are nullary and the
1007+ -- 'allNullaryToStringTag' option is set they are expected to be
1008+ -- encoded as strings. This distinction is made by 'parseSum':
1009+ gParseJSON' p =
1010+ (unTagged :: Tagged allNullary (Parser ((a :+: b) _d)) ->
1011+ Parser ((a :+: b) _d))
1012+ . parseSum p
7651013
7661014--------------------------------------------------------------------------------
7671015
7681016class ParseSum arity f allNullary where
769− parseSum :: Options -> FromArgs arity a
770− -> Value -> Tagged allNullary (Parser (f a))
771−
772−instance ( SumFromString (a :+: b)
773− , FromPair arity (a :+: b)
774− , FromTaggedObject arity (a :+: b)
775− , FromUntaggedValue arity (a :+: b)
776− ) => ParseSum arity (a :+: b) True where
777− parseSum opts fargs
778− | allNullaryToStringTag opts = Tagged . parseAllNullarySum opts
779− | otherwise = Tagged . parseNonAllNullarySum opts fargs
780−
781−instance ( FromPair arity (a :+: b)
782− , FromTaggedObject arity (a :+: b)
783− , FromUntaggedValue arity (a :+: b)
784− ) => ParseSum arity (a :+: b) False where
785− parseSum opts fargs = Tagged . parseNonAllNullarySum opts fargs
1017+ parseSum :: TypeName :* Options :* FromArgs arity a
1018+ -> Value
1019+ -> Tagged allNullary (Parser (f a))
1020+
1021+instance ( ConstructorNames f
1022+ , SumFromString f
1023+ , FromPair arity f
1024+ , FromTaggedObject arity f
1025+ , FromUntaggedValue arity f
1026+ ) => ParseSum arity f True where
1027+ parseSum p@(tname :* opts :* _)
1028+ | allNullaryToStringTag opts = Tagged . parseAllNullarySum tname opts
1029+ | otherwise = Tagged . parseNonAllNullarySum p
1030+
1031+instance ( ConstructorNames f
1032+ , FromPair arity f
1033+ , FromTaggedObject arity f
1034+ , FromUntaggedValue arity f
1035+ ) => ParseSum arity f False where
1036+ parseSum p = Tagged . parseNonAllNullarySum p
7861037
7871038--------------------------------------------------------------------------------
7881039
789−parseAllNullarySum :: SumFromString f => Options -> Value -> Parser (f a)
790−parseAllNullarySum opts = withText "Text" $ \key ->
791− maybe (notFound key) return $
792− 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])
7931062
7941063class SumFromString f where
795− parseSumFromString :: Options -> Text -> Maybe (f a)
1064+ parseSumFromString :: (String -> String) -> Text -> Maybe (f a)
7961065
7971066instance (SumFromString a, SumFromString b) => SumFromString (a :+: b) where
7981067 parseSumFromString opts key = (L1 <$> parseSumFromString opts key) <|>
7991068 (R1 <$> parseSumFromString opts key)
8001069
8011070instance (Constructor c) => SumFromString (C1 c U1) where
802− parseSumFromString opts key | key == name = Just $ M1 U1
803− | otherwise = Nothing
804− where
805− name = pack $ constructorTagModifier opts $
806− 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)
8071076
808−--------------------------------------------------------------------------------
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)
8091090
810−parseNonAllNullarySum :: ( FromPair arity (a :+: b)
811− , FromTaggedObject arity (a :+: b)
812− , FromUntaggedValue arity (a :+: b)
813− ) => Options -> FromArgs arity c
814− -> Value -> Parser ((a :+: b) c)
815−parseNonAllNullarySum opts fargs =
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
1115+ , FromTaggedObject arity f
1116+ , FromUntaggedValue arity f
1117+ , ConstructorNames f
1118+ ) => TypeName :* Options :* FromArgs arity c
1119+ -> Value -> Parser (f c)
1120+parseNonAllNullarySum p@(tname :* opts :* _) =
8161121 case sumEncoding opts of
8171122 TaggedObject{..} ->
818− withObject "Object" $ \obj -> do
819− tag <- obj .: pack tagFieldName
820− fromMaybe (notFound tag) $
821− 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])
8221133
8231134 ObjectWithSingleField ->
824− withObject "Object" $ \obj ->
825− case H.toList obj of
826− [pair@(tag, _)] -> fromMaybe (notFound tag) $
827− parsePair opts fargs pair
828− _ -> 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
8291145
8301146 TwoElemArray ->
831− withArray "Array" $ \arr ->
832− if V.length arr == 2
833− then case V.unsafeIndex arr 0 of
834− String tag -> fromMaybe (notFound tag) $
835− parsePair opts fargs (tag, V.unsafeIndex arr 1)
836− _ -> fail "First element is not a String"
837− 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
8381161
839− UntaggedValue -> parseUntaggedValue opts fargs
1162+ UntaggedValue -> parseUntaggedValue p
1163+ where
1164+ failWith_ = failWithCTags tname (constructorTagModifier opts)
8401165
8411166--------------------------------------------------------------------------------
8421167
8431168class FromTaggedObject arity f where
844− parseFromTaggedObject :: Options -> FromArgs arity a
845− -> String -> Object
846− -> 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))
8471175
8481176instance ( FromTaggedObject arity a, FromTaggedObject arity b) =>
8491177 FromTaggedObject arity (a :+: b) where
850− parseFromTaggedObject opts fargs contentsFieldName obj tag =
851− (fmap L1 <$> parseFromTaggedObject opts fargs contentsFieldName obj tag) <|>
852− (fmap R1 <$> parseFromTaggedObject opts fargs contentsFieldName obj tag)
1178+ parseFromTaggedObject p obj =
1179+ (fmap L1 <$> parseFromTaggedObject p obj) <|>
1180+ (fmap R1 <$> parseFromTaggedObject p obj)
8531181
854−instance ( FromTaggedObject' arity f
1182+instance ( IsRecord f isRecord
1183+ , FromTaggedObject' arity f isRecord
8551184 , Constructor c
8561185 ) => FromTaggedObject arity (C1 c f) where
857− parseFromTaggedObject opts fargs contentsFieldName obj tag
858− | tag == name = Just $ M1 <$> parseFromTaggedObject'
859− opts fargs contentsFieldName obj
860− | otherwise = Nothing
861− where
862− name = pack $ constructorTagModifier opts $
863− 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)
8641195
8651196--------------------------------------------------------------------------------
8661197
867−class FromTaggedObject' arity f where
868− parseFromTaggedObject' :: Options -> FromArgs arity a -> String
869− -> Object -> Parser (f a)
870−
871−class FromTaggedObject'' arity f isRecord where
872− parseFromTaggedObject'' :: Options -> FromArgs arity a -> String
873− -> Object -> Tagged isRecord (Parser (f a))
874−
875−instance ( IsRecord f isRecord
876− , FromTaggedObject'' arity f isRecord
877− ) => FromTaggedObject' arity f where
878− parseFromTaggedObject' opts fargs contentsFieldName =
879− (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a)) .
880− parseFromTaggedObject'' opts fargs contentsFieldName
881−
882−instance (FromRecord arity f) => FromTaggedObject'' arity f True where
883− parseFromTaggedObject'' opts fargs _ =
884− Tagged . parseRecord opts fargs Nothing
885−
886−instance (GFromJSON arity f) => FromTaggedObject'' arity f False where
887− parseFromTaggedObject'' opts fargs contentsFieldName = Tagged .
888− (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
8891216
890−instance OVERLAPPING_ FromTaggedObject'' arity U1 False where
891− 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)
8921220
8931221--------------------------------------------------------------------------------
8941222
1223+-- | Constructors need to be decoded differently depending on whether they're
1224+-- a record or not. This distinction is made by 'ConsParseJSON'.
8951225class ConsFromJSON arity f where
896− consParseJSON :: Options -> FromArgs arity a
897− -> Value -> Parser (f a)
1226+ consParseJSON
1227+ :: ConName :* TypeName :* Options :* FromArgs arity a
1228+ -> Value -> Parser (f a)
8981229
8991230class ConsFromJSON' arity f isRecord where
900− consParseJSON' :: Options -> FromArgs arity a
901− -> Maybe Text -- ^ A dummy label
902− -- (Nothing to use proper label)
903− -> Value -> Tagged isRecord (Parser (f a))
1231+ consParseJSON'
1232+ :: ConName :* TypeName :* Options :* FromArgs arity a
1233+ -> Value -> Tagged isRecord (Parser (f a))
9041234
9051235instance ( IsRecord f isRecord
9061236 , ConsFromJSON' arity f isRecord
9071237 ) => ConsFromJSON arity f where
908− consParseJSON opts fargs v = let
909− (v2,lab) = case (unwrapUnaryRecords opts,isUnary (undefined :: f a)) of
910− -- use a dummy object with a dummy label
911− (True,True) -> (object [(pack "dummy",v)], Just $ pack "dummy")
912− _ ->(v,Nothing)
913− in (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
914− $ consParseJSON' opts fargs lab v2
1238+ consParseJSON p =
1239+ (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
1240+ . consParseJSON' p
9151241
1242+instance OVERLAPPING_
1243+ ( GFromJSON arity a, RecordFromJSON arity (S1 s a)
1244+ ) => ConsFromJSON' arity (S1 s a) True where
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))
9161248
917−instance (FromRecord arity f) => ConsFromJSON' arity f True where
918− consParseJSON' opts fargs mlab = Tagged . withObject "record (:*:)"
919− (parseRecord opts fargs mlab)
1249+instance RecordFromJSON arity f => ConsFromJSON' arity f True where
1250+ consParseJSON' p@(cname :* tname :* _) =
1251+ Tagged . withObject (showCons cname tname) (recordParseJSON (False :* p))
9201252
921−instance (GFromJSON arity f) => ConsFromJSON' arity f False where
922− 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
9231274
9241275--------------------------------------------------------------------------------
9251276
926−class FromRecord arity f where
927− parseRecord :: Options -> FromArgs arity a
928− -> Maybe Text -- ^ A dummy label
929− -- (Nothing to use proper label)
930− -> Object -> Parser (f a)
931−
932−instance ( FromRecord arity a
933− , FromRecord arity b
934− ) => FromRecord arity (a :*: b) where
935− parseRecord opts fargs _ obj =
936− (:*:) <$> parseRecord opts fargs Nothing obj
937− <*> parseRecord opts fargs Nothing obj
938−
939−instance ( Selector s
940− , GFromJSON arity a
941− ) => FromRecord arity (S1 s a) where
942− parseRecord opts fargs lab =
943− (<?> Key label) . gParseJSON opts fargs <=< (.: label)
944− where
945− label = fromMaybe defLabel lab
946− defLabel = pack . fieldLabelModifier opts $
947− selName (undefined :: t s a p)
948−
949−instance OVERLAPPING_ (Selector s, FromJSON a) =>
950− FromRecord arity (S1 s (K1 i (Maybe a))) where
951− parseRecord _ _ (Just lab) obj = (M1 . K1) <$> obj .:? lab
952− parseRecord opts _ Nothing obj = (M1 . K1) <$> obj .:? pack label
1277+class FieldNames f where
1278+ fieldNames :: f a -> [Text] -> [Text]
1279+
1280+instance (FieldNames a, FieldNames b) => FieldNames (a :*: b) where
1281+ fieldNames _ =
1282+ fieldNames (undefined :: a x) .
1283+ fieldNames (undefined :: b y)
1284+
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
9531298 where
954− label = fieldLabelModifier opts $
955− selName (undefined :: t s (K1 i (Maybe 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)
1331+
1332+instance INCOHERENT_ (Selector s, FromJSON a) =>
1333+ RecordFromJSON' arity (S1 s (K1 i (Maybe a))) where
1334+ recordParseJSON' (_ :* _ :* opts :* _) obj = M1 . K1 <$> obj .:? pack label
1335+ where
1336+ label = fieldLabelModifier opts sname
1337+ sname = selName (undefined :: M1 _i s _f _p)
1338+
1339+-- Parse an Option like a Maybe.
1340+instance INCOHERENT_ (Selector s, FromJSON a) =>
1341+ RecordFromJSON' arity (S1 s (K1 i (Semigroup.Option a))) where
1342+ recordParseJSON' p obj = wrap <$> recordParseJSON' p obj
1343+ where
1344+ wrap :: S1 s (K1 i (Maybe a)) p -> S1 s (K1 i (Semigroup.Option a)) p
1345+ wrap (M1 (K1 a)) = M1 (K1 (Semigroup.Option a))
9561346
9571347--------------------------------------------------------------------------------
9581348
959−class FromProduct arity f where
960− 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
9611371 -> Array -> Int -> Int
9621372 -> Parser (f a)
9631373
964−instance ( FromProduct arity a
965− , FromProduct arity b
966− ) => FromProduct arity (a :*: b) where
967− parseProduct opts fargs arr ix len =
968− (:*:) <$> parseProduct opts fargs arr ix lenL
969− <*> parseProduct opts fargs arr ixR lenR
1374+instance ( ProductFromJSON arity a
1375+ , ProductFromJSON arity b
1376+ ) => ProductFromJSON arity (a :*: b) where
1377+ productParseJSON p arr ix len =
1378+ (:*:) <$> productParseJSON p arr ix lenL
1379+ <*> productParseJSON p arr ixR lenR
9701380 where
9711381 lenL = len `unsafeShiftR` 1
9721382 ixR = ix + lenL
9731383 lenR = len - lenL
9741384
975−instance (GFromJSON arity a) => FromProduct arity (S1 s a) where
976− parseProduct opts fargs arr ix _ =
977− 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 <$> gParseJSON opts fargs (V.unsafeIndex arr ix) <?> Index ix
9781388
9791389--------------------------------------------------------------------------------
9801390
9811391class FromPair arity f where
982− parsePair :: Options -> FromArgs arity a
983− -> Pair -> Maybe (Parser (f a))
1392+ -- The first component of the parameter tuple is the tag to match.
1393+ parsePair :: Text :* TypeName :* Options :* FromArgs arity a
1394+ -> Value
1395+ -> Maybe (Parser (f a))
9841396
9851397instance ( FromPair arity a
9861398 , FromPair arity b
9871399 ) => FromPair arity (a :+: b) where
988− parsePair opts fargs pair = (fmap L1 <$> parsePair opts fargs pair) <|>
989− (fmap R1 <$> parsePair opts fargs pair)
1400+ parsePair p pair =
1401+ (fmap L1 <$> parsePair p pair) <|>
1402+ (fmap R1 <$> parsePair p pair)
9901403
9911404instance ( Constructor c
992− , GFromJSON arity a
9931405 , ConsFromJSON arity a
9941406 ) => FromPair arity (C1 c a) where
995− parsePair opts fargs (tag, value)
996− | tag == tag' = Just $ gParseJSON opts fargs value
1407+ parsePair (tag :* p@(_ :* opts :* _)) v
1408+ | tag == tag' = Just $ M1 <$> consParseJSON (cname :* p) v
9971409 | otherwise = Nothing
998− where
999− tag' = pack $ constructorTagModifier opts $
1000− conName (undefined :: t c a p)
1410+ where
1411+ tag' = pack $ constructorTagModifier opts cname
1412+ cname = conName (undefined :: M1 _i c _a _p)
10011413
10021414--------------------------------------------------------------------------------
10031415
10041416class FromUntaggedValue arity f where
1005− parseUntaggedValue :: Options -> FromArgs arity a
1006− -> Value -> Parser (f a)
1417+ parseUntaggedValue :: TypeName :* Options :* FromArgs arity a
1418+ -> Value
1419+ -> Parser (f a)
10071420
10081421instance
10091422 ( FromUntaggedValue arity a
10101423 , FromUntaggedValue arity b
10111424 ) => FromUntaggedValue arity (a :+: b)
10121425 where
1013− parseUntaggedValue opts fargs value =
1014− L1 <$> parseUntaggedValue opts fargs value <|>
1015− R1 <$> parseUntaggedValue opts fargs value
1426+ parseUntaggedValue p value =
1427+ L1 <$> parseUntaggedValue p value <|>
1428+ R1 <$> parseUntaggedValue p value
10161429
10171430instance OVERLAPPABLE_
1018− ( GFromJSON arity a
1019− , ConsFromJSON arity a
1431+ ( ConsFromJSON arity a
1432+ , Constructor c
10201433 ) => FromUntaggedValue arity (C1 c a)
10211434 where
1022− parseUntaggedValue = gParseJSON
1435+ parseUntaggedValue p = fmap M1 . consParseJSON (cname :* p)
1436+ where
1437+ cname = conName (undefined :: M1 _i c _f _p)
10231438
10241439instance OVERLAPPING_
10251440 ( Constructor c )
10261441 => FromUntaggedValue arity (C1 c U1)
10271442 where
1028− parseUntaggedValue opts _ (String s)
1029− | s == pack (constructorTagModifier opts (conName (undefined :: t c U1 p))) =
1030− pure $ M1 U1
1031− | otherwise =
1032− fail $ "Invalid tag: " ++ unpack s
1033− parseUntaggedValue _ _ v = typeMismatch (conName (undefined :: t c U1 p)) v
1034−
1035−
1036−--------------------------------------------------------------------------------
1037−
1038−notFound :: Text -> Parser a
1039−notFound key = fail $ "The key \"" ++ unpack key ++ "\" was not found"
1040−{-# 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
10411454
10421455-------------------------------------------------------------------------------
10431456-- Instances
@@ -1095,17 +1508,20 @@ instance (FromJSON a, FromJSON b) => FromJSON (Either a b) where
10951508 parseJSON = parseJSON2
10961509 {-# INLINE parseJSON #-}
10971510
1098−
1511+instance FromJSON Void where
1512+ parseJSON _ = fail "Cannot parse Void"
1513+ {-# INLINE parseJSON #-}
10991514
11001515instance FromJSON Bool where
1101− parseJSON = withBool "Bool" pure
1516+ parseJSON (Bool b) = pure b
1517+ parseJSON v = typeMismatch "Bool" v
11021518 {-# INLINE parseJSON #-}
11031519
11041520instance FromJSONKey Bool where
11051521 fromJSONKey = FromJSONKeyTextParser $ \t -> case t of
11061522 "true" -> pure True
11071523 "false" -> pure False
1108− _ -> fail $ "Cannot parse key into Bool: " ++ T.unpack t
1524+ _ -> fail $ "cannot parse key " ++ show t ++ " into Bool"
11091525
11101526instance FromJSON Ordering where
11111527 parseJSON = withText "Ordering" $ \s ->
@@ -1113,25 +1529,30 @@ instance FromJSON Ordering where
11131529 "LT" -> return LT
11141530 "EQ" -> return EQ
11151531 "GT" -> return GT
1116− _ -> fail "Parsing Ordering value failed: expected \"LT\", \"EQ\", or \"GT\""
1532+ _ -> fail $ "parsing Ordering failed, unexpected " ++ show s ++
1533+ " (expected \"LT\", \"EQ\", or \"GT\")"
11171534
11181535instance FromJSON () where
11191536 parseJSON = withArray "()" $ \v ->
11201537 if V.null v
11211538 then pure ()
1122− else fail "Expected an empty array"
1539+ else prependContext "()" $ fail "expected an empty array"
11231540 {-# INLINE parseJSON #-}
11241541
11251542instance FromJSON Char where
1126− parseJSON = withText "Char" $ \t ->
1127− if T.compareLength t 1 == EQ
1128− then pure $ T.head t
1129− else fail "Expected a string of length 1"
1543+ parseJSON = withText "Char" parseChar
11301544 {-# INLINE parseJSON #-}
11311545
1132− parseJSONList = withText "String" $ pure . T.unpack
1546+ parseJSONList (String s) = pure (T.unpack s)
1547+ parseJSONList v = typeMismatch "String" v
11331548 {-# INLINE parseJSONList #-}
11341549
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+
11351556instance FromJSON Double where
11361557 parseJSON = parseRealFloat "Double"
11371558 {-# INLINE parseJSON #-}
@@ -1143,12 +1564,6 @@ instance FromJSONKey Double where
11431564 "-Infinity" -> pure (negate 1/0)
11441565 _ -> Scientific.toRealFloat <$> parseScientificText t
11451566
1146−instance FromJSON Number where
1147− parseJSON (Number s) = pure $ scientificToNumber s
1148− parseJSON Null = pure (D (0/0))
1149− parseJSON v = typeMismatch "Number" v
1150− {-# INLINE parseJSON #-}
1151−
11521567instance FromJSON Float where
11531568 parseJSON = parseRealFloat "Float"
11541569 {-# INLINE parseJSON #-}
@@ -1161,17 +1576,30 @@ instance FromJSONKey Float where
11611576 _ -> Scientific.toRealFloat <$> parseScientificText t
11621577
11631578instance (FromJSON a, Integral a) => FromJSON (Ratio a) where
1164− parseJSON = withObject "Rational" $ \obj ->
1165− (%) <$> obj .: "numerator"
1166− <*> obj .: "denominator"
1167− {-# INLINE parseJSON #-}
1168−
1169−-- | /WARNING:/ Only parse fixed-precision numbers from trusted input
1170−-- since an attacker could easily fill up the memory of the target
1171−-- system by specifying a scientific number with a big exponent like
1172−-- @1e1000000000@.
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
1595+ {-# INLINE parseJSON #-}
1596+
1597+-- | This instance includes a bounds check to prevent maliciously
1598+-- large inputs to fill up the memory of the target system. You can
1599+-- newtype 'Scientific' and provide your own instance using
1600+-- 'withScientific' if you want to allow larger inputs.
11731601instance HasResolution a => FromJSON (Fixed a) where
1174− parseJSON = withScientific "Fixed" $ pure . realToFrac
1602+ parseJSON = prependContext "Fixed" . withBoundedScientific' (pure . realToFrac)
11751603 {-# INLINE parseJSON #-}
11761604
11771605instance FromJSON Int where
@@ -1181,10 +1609,10 @@ instance FromJSON Int where
11811609instance FromJSONKey Int where
11821610 fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int"
11831611
1184−-- | /WARNING:/ Only parse Integers from trusted input since an
1185−-- attacker could easily fill up the memory of the target system by
1186−-- specifying a scientific number with a big exponent like
1187−-- @1e1000000000@.
1612+-- | This instance includes a bounds check to prevent maliciously
1613+-- large inputs to fill up the memory of the target system. You can
1614+-- newtype 'Scientific' and provide your own instance using
1615+-- 'withScientific' if you want to allow larger inputs.
11881616instance FromJSON Integer where
11891617 parseJSON = parseIntegral "Integer"
11901618 {-# INLINE parseJSON #-}
@@ -1193,16 +1621,21 @@ instance FromJSONKey Integer where
11931621 fromJSONKey = FromJSONKeyTextParser $ parseIntegralText "Integer"
11941622
11951623instance FromJSON Natural where
1196− parseJSON = withScientific "Natural" $ \s ->
1197− if Scientific.coefficient s < 0
1198− then fail $ "Expected a Natural number but got the negative number: " <> show s
1199− else pure $ truncate s
1624+ parseJSON value = do
1625+ integer <- parseIntegral "Natural" value
1626+ parseNatural integer
12001627
12011628instance FromJSONKey Natural where
1202− fromJSONKey = FromJSONKeyTextParser $ \t -> parseScientificText t >>= \s ->
1203− if Scientific.coefficient s < 0
1204− then fail $ "Expected a Natural number but got the negative number: " <> show s
1205− else pure $ truncate s
1629+ fromJSONKey = FromJSONKeyTextParser $ \text -> do
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
12061639
12071640instance FromJSON Int8 where
12081641 parseJSON = parseBoundedIntegral "Int8"
@@ -1267,6 +1700,9 @@ instance FromJSON Word64 where
12671700instance FromJSONKey Word64 where
12681701 fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word64"
12691702
1703+instance FromJSON CTime where
1704+ parseJSON = fmap CTime . parseJSON
1705+ {-# INLINE parseJSON #-}
12701706
12711707instance FromJSON Text where
12721708 parseJSON = withText "Text" pure
@@ -1296,17 +1732,17 @@ parseVersionText = go . readP_to_S parseVersion . unpack
12961732 where
12971733 go [(v,[])] = return v
12981734 go (_ : xs) = go xs
1299− go _ = fail "could not parse Version"
1735+ go _ = fail "parsing Version failed"
13001736
13011737-------------------------------------------------------------------------------
13021738-- semigroups NonEmpty
13031739-------------------------------------------------------------------------------
13041740
13051741instance FromJSON1 NonEmpty where
1306− liftParseJSON p _ = withArray "NonEmpty a" $
1742+ liftParseJSON p _ = withArray "NonEmpty" $
13071743 (>>= ne) . Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
13081744 where
1309− ne [] = fail "Expected a NonEmpty but got an empty list"
1745+ ne [] = fail "parsing NonEmpty failed, unexpected empty list"
13101746 ne (x:xs) = pure (x :| xs)
13111747 {-# INLINE liftParseJSON #-}
13121748
@@ -1327,7 +1763,7 @@ instance FromJSON Scientific where
13271763-------------------------------------------------------------------------------
13281764
13291765instance FromJSON1 DList.DList where
1330− liftParseJSON p _ = withArray "DList a" $
1766+ liftParseJSON p _ = withArray "DList" $
13311767 fmap DList.fromList .
13321768 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
13331769 {-# INLINE liftParseJSON #-}
@@ -1354,7 +1790,7 @@ instance (FromJSON a) => FromJSON (Identity a) where
13541790 parseJSONList = liftParseJSONList parseJSON parseJSONList
13551791 {-# INLINE parseJSONList #-}
13561792
1357−instance (FromJSONKey a, FromJSON a) => FromJSONKey (Identity a) where
1793+instance (FromJSONKey a) => FromJSONKey (Identity a) where
13581794 fromJSONKey = coerceFromJSONKeyFunction (fromJSONKey :: FromJSONKeyFunction a)
13591795 fromJSONKeyList = coerceFromJSONKeyFunction (fromJSONKeyList :: FromJSONKeyFunction [a])
13601796
@@ -1404,7 +1840,7 @@ instance (FromJSON1 f, FromJSON1 g) => FromJSON1 (Sum f g) where
14041840 inr = "InR"
14051841
14061842 liftParseJSON _ _ _ = fail $
1407− "expected an object with a single property " ++
1843+ "parsing Sum failed, expected an object with a single property " ++
14081844 "where the property key should be either " ++
14091845 "\"InL\" or \"InR\""
14101846 {-# INLINE liftParseJSON #-}
@@ -1418,7 +1854,7 @@ instance (FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum f g a) where
14181854-------------------------------------------------------------------------------
14191855
14201856instance FromJSON1 Seq.Seq where
1421− liftParseJSON p _ = withArray "Seq a" $
1857+ liftParseJSON p _ = withArray "Seq" $
14221858 fmap Seq.fromList .
14231859 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
14241860 {-# INLINE liftParseJSON #-}
@@ -1452,15 +1888,15 @@ instance FromJSON a => FromJSON (IntMap.IntMap a) where
14521888
14531889instance (FromJSONKey k, Ord k) => FromJSON1 (M.Map k) where
14541890 liftParseJSON p _ = case fromJSONKey of
1455− FromJSONKeyCoerce _-> withObject "Map k v" $
1891+ FromJSONKeyCoerce _ -> withObject "Map" $
14561892 fmap (H.foldrWithKey (M.insert . unsafeCoerce) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1457− FromJSONKeyText f -> withObject "Map k v" $
1893+ FromJSONKeyText f -> withObject "Map" $
14581894 fmap (H.foldrWithKey (M.insert . f) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1459− FromJSONKeyTextParser f -> withObject "Map k v" $
1895+ FromJSONKeyTextParser f -> withObject "Map" $
14601896 H.foldrWithKey (\k v m -> M.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure M.empty)
1461− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1462− M.fromList <$> (Tr.sequence .
1463− zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr)
1897+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
1898+ fmap M.fromList . Tr.sequence .
1899+ zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
14641900 {-# INLINE liftParseJSON #-}
14651901
14661902instance (FromJSONKey k, Ord k, FromJSON v) => FromJSON (M.Map k v) where
@@ -1480,12 +1916,24 @@ instance (FromJSON v) => FromJSON (Tree.Tree v) where
14801916 parseJSON = parseJSON1
14811917 {-# INLINE parseJSON #-}
14821918
1919+-------------------------------------------------------------------------------
1920+-- uuid
1921+-------------------------------------------------------------------------------
1922+
1923+instance FromJSON UUID.UUID where
1924+ parseJSON = withText "UUID" $
1925+ maybe (fail "invalid UUID") pure . UUID.fromText
1926+
1927+instance FromJSONKey UUID.UUID where
1928+ fromJSONKey = FromJSONKeyTextParser $
1929+ maybe (fail "invalid UUID") pure . UUID.fromText
1930+
14831931-------------------------------------------------------------------------------
14841932-- vector
14851933-------------------------------------------------------------------------------
14861934
14871935instance FromJSON1 Vector where
1488− liftParseJSON p _ = withArray "Vector a" $
1936+ liftParseJSON p _ = withArray "Vector" $
14891937 V.mapM (uncurry $ parseIndexedJSON p) . V.indexed
14901938 {-# INLINE liftParseJSON #-}
14911939
@@ -1499,14 +1947,14 @@ vectorParseJSON s = withArray s $ fmap V.convert . V.mapM (uncurry $ parseIndexe
14991947{-# INLINE vectorParseJSON #-}
15001948
15011949instance (Storable a, FromJSON a) => FromJSON (VS.Vector a) where
1502− parseJSON = vectorParseJSON "Data.Vector.Storable.Vector a"
1950+ parseJSON = vectorParseJSON "Data.Vector.Storable.Vector"
15031951
15041952instance (VP.Prim a, FromJSON a) => FromJSON (VP.Vector a) where
1505− parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector a"
1953+ parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector"
15061954 {-# INLINE parseJSON #-}
15071955
15081956instance (VG.Vector VU.Vector a, FromJSON a) => FromJSON (VU.Vector a) where
1509− parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector a"
1957+ parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector"
15101958 {-# INLINE parseJSON #-}
15111959
15121960-------------------------------------------------------------------------------
@@ -1520,15 +1968,15 @@ instance (Eq a, Hashable a, FromJSON a) => FromJSON (HashSet.HashSet a) where
15201968
15211969instance (FromJSONKey k, Eq k, Hashable k) => FromJSON1 (H.HashMap k) where
15221970 liftParseJSON p _ = case fromJSONKey of
1523− FromJSONKeyCoerce _ -> withObject "HashMap ~Text v" $
1971+ FromJSONKeyCoerce _ -> withObject "HashMap ~Text" $
15241972 uc . H.traverseWithKey (\k v -> p v <?> Key k)
1525− FromJSONKeyText f -> withObject "HashMap k v" $
1973+ FromJSONKeyText f -> withObject "HashMap" $
15261974 fmap (mapKey f) . H.traverseWithKey (\k v -> p v <?> Key k)
1527− FromJSONKeyTextParser f -> withObject "HashMap k v" $
1975+ FromJSONKeyTextParser f -> withObject "HashMap" $
15281976 H.foldrWithKey (\k v m -> H.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure H.empty)
1529− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1530− H.fromList <$> (Tr.sequence .
1531− zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr)
1977+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
1978+ fmap H.fromList . Tr.sequence .
1979+ zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
15321980 where
15331981 uc :: Parser (H.HashMap Text v) -> Parser (H.HashMap k v)
15341982 uc = unsafeCoerce
@@ -1549,11 +1997,33 @@ instance FromJSON DotNetTime where
15491997 parseJSON = withText "DotNetTime" $ \t ->
15501998 let (s,m) = T.splitAt (T.length t - 5) t
15511999 t' = T.concat [s,".",m]
1552− in case parseTime defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
2000+ in case parseTimeM True defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
15532001 Just d -> pure (DotNetTime d)
15542002 _ -> fail "could not parse .NET time"
15552003 {-# INLINE parseJSON #-}
15562004
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+
15572027-------------------------------------------------------------------------------
15582028-- time
15592029-------------------------------------------------------------------------------
@@ -1579,6 +2049,17 @@ instance FromJSONKey LocalTime where
15792049 fromJSONKey = FromJSONKeyTextParser (Time.run Time.localTime)
15802050
15812051
2052+-- | Supported string formats:
2053+--
2054+-- @YYYY-MM-DD HH:MM Z@
2055+-- @YYYY-MM-DD HH:MM:SS Z@
2056+-- @YYYY-MM-DD HH:MM:SS.SSS Z@
2057+--
2058+-- The first space may instead be a @T@, and the second space is
2059+-- optional. The @Z@ represents UTC. The @Z@ may be replaced with a
2060+-- time zone offset of the form @+0000@ or @-08:00@, where the first
2061+-- two digits are hours, the @:@ is optional and the second two digits
2062+-- (also optional) are minutes.
15822063instance FromJSON ZonedTime where
15832064 parseJSON = withText "ZonedTime" (Time.run Time.zonedTime)
15842065
@@ -1593,41 +2074,168 @@ instance FromJSONKey UTCTime where
15932074 fromJSONKey = FromJSONKeyTextParser (Time.run Time.utcTime)
15942075
15952076
1596−-- | /WARNING:/ Only parse lengths of time from trusted input
1597−-- since an attacker could easily fill up the memory of the target
1598−-- system by specifying a scientific number with a big exponent like
1599−-- @1e1000000000@.
2077+-- | This instance includes a bounds check to prevent maliciously
2078+-- large inputs to fill up the memory of the target system. You can
2079+-- newtype 'Scientific' and provide your own instance using
2080+-- 'withScientific' if you want to allow larger inputs.
16002081instance FromJSON NominalDiffTime where
1601− parseJSON = withScientific "NominalDiffTime" $ pure . realToFrac
2082+ parseJSON = withBoundedScientific "NominalDiffTime" $ pure . realToFrac
16022083 {-# INLINE parseJSON #-}
16032084
2085+
2086+-- | This instance includes a bounds check to prevent maliciously
2087+-- large inputs to fill up the memory of the target system. You can
2088+-- newtype 'Scientific' and provide your own instance using
2089+-- 'withScientific' if you want to allow larger inputs.
2090+instance FromJSON DiffTime where
2091+ parseJSON = withBoundedScientific "DiffTime" $ pure . realToFrac
2092+ {-# INLINE parseJSON #-}
2093+
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+ <$> obj .: "months"
2109+ <*> obj .: "days"
2110+
2111+instance FromJSON DayOfWeek where
2112+ parseJSON = withText "DaysOfWeek" parseDayOfWeek
2113+
2114+parseDayOfWeek :: T.Text -> Parser DayOfWeek
2115+parseDayOfWeek t = case T.toLower t of
2116+ "monday" -> return Monday
2117+ "tuesday" -> return Tuesday
2118+ "wednesday" -> return Wednesday
2119+ "thursday" -> return Thursday
2120+ "friday" -> return Friday
2121+ "saturday" -> return Saturday
2122+ "sunday" -> return Sunday
2123+ _ -> fail "Invalid week day"
2124+
2125+instance FromJSONKey DayOfWeek where
2126+ fromJSONKey = FromJSONKeyTextParser parseDayOfWeek
2127+
16042128-------------------------------------------------------------------------------
16052129-- base Monoid/Semigroup
16062130-------------------------------------------------------------------------------
16072131
1608−instance FromJSON1 Dual where
1609− liftParseJSON p _ = fmap Dual . p
2132+instance FromJSON1 Monoid.Dual where
2133+ liftParseJSON p _ = fmap Monoid.Dual . p
2134+ {-# INLINE liftParseJSON #-}
2135+
2136+instance FromJSON a => FromJSON (Monoid.Dual a) where
2137+ parseJSON = parseJSON1
2138+ {-# INLINE parseJSON #-}
2139+
2140+
2141+instance FromJSON1 Monoid.First where
2142+ liftParseJSON p p' = fmap Monoid.First . liftParseJSON p p'
2143+ {-# INLINE liftParseJSON #-}
2144+
2145+instance FromJSON a => FromJSON (Monoid.First a) where
2146+ parseJSON = parseJSON1
2147+ {-# INLINE parseJSON #-}
2148+
2149+
2150+instance FromJSON1 Monoid.Last where
2151+ liftParseJSON p p' = fmap Monoid.Last . liftParseJSON p p'
2152+ {-# INLINE liftParseJSON #-}
2153+
2154+instance FromJSON a => FromJSON (Monoid.Last a) where
2155+ parseJSON = parseJSON1
2156+ {-# INLINE parseJSON #-}
2157+
2158+
2159+instance FromJSON1 Semigroup.Min where
2160+ liftParseJSON p _ a = Semigroup.Min <$> p a
2161+ {-# INLINE liftParseJSON #-}
2162+
2163+ liftParseJSONList _ p a = fmap Semigroup.Min <$> p a
2164+ {-# INLINE liftParseJSONList #-}
2165+
2166+instance (FromJSON a) => FromJSON (Semigroup.Min a) where
2167+ parseJSON = parseJSON1
2168+ {-# INLINE parseJSON #-}
2169+
2170+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2171+ {-# INLINE parseJSONList #-}
2172+
2173+
2174+instance FromJSON1 Semigroup.Max where
2175+ liftParseJSON p _ a = Semigroup.Max <$> p a
2176+ {-# INLINE liftParseJSON #-}
2177+
2178+ liftParseJSONList _ p a = fmap Semigroup.Max <$> p a
2179+ {-# INLINE liftParseJSONList #-}
2180+
2181+instance (FromJSON a) => FromJSON (Semigroup.Max a) where
2182+ parseJSON = parseJSON1
2183+ {-# INLINE parseJSON #-}
2184+
2185+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2186+ {-# INLINE parseJSONList #-}
2187+
2188+
2189+instance FromJSON1 Semigroup.First where
2190+ liftParseJSON p _ a = Semigroup.First <$> p a
16102191 {-# INLINE liftParseJSON #-}
16112192
1612−instance FromJSON a => FromJSON (Dual a) where
2193+ liftParseJSONList _ p a = fmap Semigroup.First <$> p a
2194+ {-# INLINE liftParseJSONList #-}
2195+
2196+instance (FromJSON a) => FromJSON (Semigroup.First a) where
16132197 parseJSON = parseJSON1
16142198 {-# INLINE parseJSON #-}
16152199
2200+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2201+ {-# INLINE parseJSONList #-}
2202+
16162203
1617−instance FromJSON1 First where
1618− liftParseJSON p p' = fmap First . liftParseJSON p p'
2204+instance FromJSON1 Semigroup.Last where
2205+ liftParseJSON p _ a = Semigroup.Last <$> p a
16192206 {-# INLINE liftParseJSON #-}
16202207
1621−instance FromJSON a => FromJSON (First a) where
2208+ liftParseJSONList _ p a = fmap Semigroup.Last <$> p a
2209+ {-# INLINE liftParseJSONList #-}
2210+
2211+instance (FromJSON a) => FromJSON (Semigroup.Last a) where
16222212 parseJSON = parseJSON1
16232213 {-# INLINE parseJSON #-}
16242214
2215+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2216+ {-# INLINE parseJSONList #-}
16252217
1626−instance FromJSON1 Last where
1627− liftParseJSON p p' = fmap Last . liftParseJSON p p'
2218+
2219+instance FromJSON1 Semigroup.WrappedMonoid where
2220+ liftParseJSON p _ a = Semigroup.WrapMonoid <$> p a
2221+ {-# INLINE liftParseJSON #-}
2222+
2223+ liftParseJSONList _ p a = fmap Semigroup.WrapMonoid <$> p a
2224+ {-# INLINE liftParseJSONList #-}
2225+
2226+instance (FromJSON a) => FromJSON (Semigroup.WrappedMonoid a) where
2227+ parseJSON = parseJSON1
2228+ {-# INLINE parseJSON #-}
2229+
2230+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2231+ {-# INLINE parseJSONList #-}
2232+
2233+
2234+instance FromJSON1 Semigroup.Option where
2235+ liftParseJSON p p' = fmap Semigroup.Option . liftParseJSON p p'
16282236 {-# INLINE liftParseJSON #-}
16292237
1630−instance FromJSON a => FromJSON (Last a) where
2238+instance FromJSON a => FromJSON (Semigroup.Option a) where
16312239 parseJSON = parseJSON1
16322240 {-# INLINE parseJSON #-}
16332241
@@ -1635,11 +2243,21 @@ instance FromJSON a => FromJSON (Last a) where
16352243-- tagged
16362244-------------------------------------------------------------------------------
16372245
2246+instance FromJSON1 Proxy where
2247+ {-# INLINE liftParseJSON #-}
2248+ liftParseJSON _ _ = fromNull "Proxy" Proxy
2249+
16382250instance FromJSON (Proxy a) where
16392251 {-# INLINE parseJSON #-}
1640− parseJSON Null = pure Proxy
1641− parseJSON v = typeMismatch "Proxy" v
2252+ parseJSON = fromNull "Proxy" Proxy
16422253
2254+fromNull :: String -> a -> Value -> Parser a
2255+fromNull _ a Null = pure a
2256+fromNull c _ v = prependContext c (typeMismatch "Null" v)
2257+
2258+instance FromJSON2 Tagged where
2259+ liftParseJSON2 _ _ p _ = fmap Tagged . p
2260+ {-# INLINE liftParseJSON2 #-}
16432261
16442262instance FromJSON1 (Tagged a) where
16452263 liftParseJSON p _ = fmap Tagged . p
@@ -1662,10 +2280,7 @@ instance (FromJSON a, FromJSON b, FromJSON c) => FromJSONKey (a,b,c)
16622280instance (FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSONKey (a,b,c,d)
16632281
16642282instance FromJSONKey Char where
1665− fromJSONKey = FromJSONKeyTextParser $ \t ->
1666− if T.length t == 1
1667− then return (T.index t 0)
1668− else typeMismatch "Expected Char but String didn't contain exactly one character" (String t)
2283+ fromJSONKey = FromJSONKeyTextParser parseChar
16692284 fromJSONKeyList = FromJSONKeyText T.unpack
16702285
16712286instance (FromJSONKey a, FromJSON a) => FromJSONKey [a] where