@@ -1,29 +1,28 @@
1−{-# LANGUAGE CPP #-}
2−{-# LANGUAGE DataKinds #-}
3−{-# LANGUAGE DefaultSignatures #-}
4−{-# LANGUAGE FlexibleContexts #-}
5−{-# LANGUAGE FlexibleInstances #-}
6−{-# LANGUAGE GADTs #-}
1+{-# LANGUAGE CPP #-}
2+{-# LANGUAGE DataKinds #-}
3+{-# LANGUAGE DefaultSignatures #-}
4+{-# LANGUAGE FlexibleContexts #-}
5+{-# LANGUAGE FlexibleInstances #-}
6+{-# LANGUAGE GADTs #-}
77{-# LANGUAGE MultiParamTypeClasses #-}
8−{-# LANGUAGE NamedFieldPuns #-}
9−{-# LANGUAGE OverloadedStrings #-}
10−{-# LANGUAGE RecordWildCards #-}
11−{-# LANGUAGE ScopedTypeVariables #-}
12−{-# LANGUAGE TypeOperators #-}
13−{-# LANGUAGE TypeSynonymInstances #-}
14−{-# LANGUAGE UndecidableInstances #-}
15−{-# LANGUAGE ViewPatterns #-}
16−
17−#if __GLASGOW_HASKELL__ >= 706
18−{-# LANGUAGE PolyKinds #-}
19−#endif
20−
8+{-# LANGUAGE NoImplicitPrelude #-}
9+{-# LANGUAGE OverloadedStrings #-}
10+{-# LANGUAGE PolyKinds #-}
11+{-# LANGUAGE RecordWildCards #-}
12+{-# LANGUAGE ScopedTypeVariables #-}
13+{-# LANGUAGE TypeOperators #-}
14+{-# LANGUAGE TupleSections #-}
15+{-# LANGUAGE UndecidableInstances #-}
16+{-# LANGUAGE ViewPatterns #-}
17+
18+#include "incoherent-compat.h"
2119#include "overlapping-compat.h"
2220
2321-- TODO: Drop this when we remove support for Data.Attoparsec.Number
2422{-# OPTIONS_GHC -fno-warn-deprecations #-}
2523
26−module Data.Aeson.Types.FromJSON (
24+module Data.Aeson.Types.FromJSON
25+ (
2726 -- * Core JSON classes
2827 FromJSON(..)
2928 -- * Liftings to unary and binary type constructors
@@ -33,6 +32,7 @@ module Data.Aeson.Types.FromJSON (
3332 , parseJSON2
3433 -- * Generic JSON classes
3534 , GFromJSON(..)
35+ , FromArgs(..)
3636 , genericParseJSON
3737 , genericLiftParseJSON
3838 -- * Classes and types for map keys
@@ -42,103 +42,121 @@ module Data.Aeson.Types.FromJSON (
4242 , coerceFromJSONKeyFunction
4343 , mapFromJSONKeyFunction
4444
45+ , GFromJSONKey()
46+ , genericFromJSONKey
47+
4548 -- * List functions
4649 , listParser
4750
48− -- * Inspecting @'Value's@
51+ -- * Inspecting @'Value's@
4952 , withObject
5053 , withText
5154 , withArray
52− , withNumber
5355 , withScientific
5456 , withBool
57+ , withEmbeddedJSON
5558
5659 -- * Functions
5760 , fromJSON
5861 , ifromJSON
62+ , typeMismatch
63+ , unexpected
64+ , parseField
65+ , parseFieldMaybe
66+ , parseFieldMaybe'
67+ , explicitParseField
68+ , explicitParseFieldMaybe
69+ , explicitParseFieldMaybe'
70+ , parseIndexedJSON
71+ -- ** Operators
5972 , (.:)
6073 , (.:?)
6174 , (.:!)
6275 , (.!=)
63− , typeMismatch
6476
6577 -- * Internal
6678 , parseOptionalFieldWith
6779 ) where
6880
69−import Prelude ()
70−import Prelude.Compat hiding (foldr)
81+import Prelude.Compat
7182
83+import Control.Applicative ((<|>), Const(..), liftA2)
84+import Control.Monad (zipWithM)
7285import Data.Aeson.Internal.Functions (mapKey)
86+import Data.Aeson.Parser.Internal (eitherDecodeWith, jsonEOF)
7387import Data.Aeson.Types.Generic
7488import Data.Aeson.Types.Internal
75−
76−import qualified Data.Aeson.Parser.Time as Time
77−import qualified Data.Attoparsec.ByteString.Char8 as A (endOfInput, parseOnly,
78− scientific)
79−
80−import Control.Applicative (Const (..), (<|>))
81−import Control.Monad ((<=<))
82−import Data.Attoparsec.Number (Number (..))
83−import Data.Bits (unsafeShiftR)
84−import Data.Fixed (Fixed, HasResolution)
85−import Data.Functor.Identity (Identity (..))
86−import Data.Hashable (Hashable (..))
87−import Data.Int (Int16, Int32, Int64, Int8)
88−import Data.List.NonEmpty (NonEmpty (..))
89−import Data.Maybe (fromMaybe)
90−import Data.Monoid (Dual (..), First (..), Last (..), (<>))
91−import Data.Proxy (Proxy (..))
92−import Data.Ratio (Ratio, (%))
93−import Data.Scientific (Scientific)
94−import Data.Tagged (Tagged (..))
95−import Data.Text (Text, pack, unpack)
96−import Data.Time (Day, LocalTime, NominalDiffTime, TimeOfDay,
97− UTCTime, ZonedTime)
98−import Data.Time.Format (parseTime)
99−import Data.Time.Locale.Compat (defaultTimeLocale)
100−import Data.Traversable as Tr (sequence)
101−import Data.Vector (Vector)
102−import Data.Version (Version, parseVersion)
103−import Data.Word (Word16, Word32, Word64, Word8)
104−import Foreign.Storable (Storable)
89+import Data.Bits (unsafeShiftR)
90+import Data.Fixed (Fixed, HasResolution (resolution), Nano)
91+import Data.Functor.Compose (Compose(..))
92+import Data.Functor.Identity (Identity(..))
93+import Data.Functor.Product (Product(..))
94+import Data.Functor.Sum (Sum(..))
95+import Data.Hashable (Hashable(..))
96+import Data.Int (Int16, Int32, Int64, Int8)
97+import Data.List.NonEmpty (NonEmpty(..))
98+import Data.Maybe (fromMaybe)
99+import Data.Semigroup ((<>))
100+import Data.Proxy (Proxy(..))
101+import Data.Ratio ((%), Ratio)
102+import Data.Scientific (Scientific, base10Exponent)
103+import Data.Tagged (Tagged(..))
104+import Data.Text (Text, pack, unpack)
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)
110+import Data.Traversable as Tr (sequence)
111+import Data.Vector (Vector)
112+import Data.Version (Version, parseVersion)
113+import Data.Void (Void)
114+import Data.Word (Word16, Word32, Word64, Word8)
115+import Foreign.Storable (Storable)
116+import Foreign.C.Types (CTime (..))
105117import GHC.Generics
106−import Numeric.Natural (Natural)
118+import Numeric.Natural (Natural)
107119import Text.ParserCombinators.ReadP (readP_to_S)
108−
109−import qualified Data.DList as DList
110−import qualified Data.HashMap.Strict as H
111−import qualified Data.HashSet as HashSet
112−import qualified Data.IntMap as IntMap
113−import qualified Data.IntSet as IntSet
114−import qualified Data.Map as M
115−import qualified Data.Scientific as Scientific
116−import qualified Data.Sequence as Seq
117−import qualified Data.Set as Set
118−import qualified Data.Text as T
119−import qualified Data.Text.Encoding as T
120−import qualified Data.Text.Lazy as LT
121−import qualified Data.Tree as Tree
122−import qualified Data.Vector as V
123−import qualified Data.Vector.Generic as VG
120+import Unsafe.Coerce (unsafeCoerce)
121+import qualified Data.Aeson.Parser.Time as Time
122+import qualified Data.Attoparsec.ByteString.Char8 as A (endOfInput, parseOnly, scientific)
123+import qualified Data.ByteString.Lazy as L
124+import qualified Data.DList as DList
125+import qualified Data.HashMap.Strict as H
126+import qualified Data.HashSet as HashSet
127+import qualified Data.IntMap as IntMap
128+import qualified Data.IntSet as IntSet
129+import qualified Data.Map as M
130+import qualified Data.Monoid as Monoid
131+import qualified Data.Scientific as Scientific
132+import qualified Data.Semigroup as Semigroup
133+import qualified Data.Sequence as Seq
134+import qualified Data.Set as Set
135+import qualified Data.Text as T
136+import qualified Data.Text.Encoding as T
137+import qualified Data.Text.Lazy as LT
138+import qualified Data.Tree as Tree
139+import qualified Data.UUID.Types as UUID
140+import qualified Data.Vector as V
141+import qualified Data.Vector.Generic as VG
124142import qualified Data.Vector.Primitive as VP
125−import qualified Data.Vector.Storable as VS
126−import qualified Data.Vector.Unboxed as VU
143+import qualified Data.Vector.Storable as VS
144+import qualified Data.Vector.Unboxed as VU
127145
128−import Unsafe.Coerce (unsafeCoerce)
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
129150
130−#ifndef HAS_COERCIBLE
131−#define HAS_COERCIBLE (__GLASGOW_HASKELL__ >= 707)
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
132156#endif
133157
134−#if HAS_COERCIBLE
158+
135159import Data.Coerce (Coercible, coerce)
136−coerce' :: Coercible a b => a -> b
137−coerce' = coerce
138−#else
139−coerce' :: a -> b
140−coerce' = unsafeCoerce
141−#endif
142160
143161parseIndexedJSON :: (Value -> Parser a) -> Int -> Value -> Parser a
144162parseIndexedJSON p idx value = p value <?> Index idx
@@ -147,7 +165,7 @@ parseIndexedJSON p idx value = p value <?> Index idx
147165parseIndexedJSONPair :: (Value -> Parser a) -> (Value -> Parser b) -> Int -> Value -> Parser (a, b)
148166parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
149167 where
150− p = withArray "(k,v)" $ \ab ->
168+ p = withArray "(k, v)" $ \ab ->
151169 let n = V.length ab
152170 in if n == 2
153171 then (,) <$> parseJSONElemAtIndex keyParser 0 ab
@@ -159,33 +177,57 @@ parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
159177parseJSONElemAtIndex :: (Value -> Parser a) -> Int -> V.Vector Value -> Parser a
160178parseJSONElemAtIndex p idx ary = p (V.unsafeIndex ary idx) <?> Index idx
161179
162−scientificToNumber :: Scientific -> Number
163−scientificToNumber s
164− | e < 0 = D $ Scientific.toRealFloat s
165− | otherwise = I $ c * 10 ^ e
166− where
167− e = Scientific.base10Exponent s
168− c = Scientific.coefficient s
169−{-# INLINE scientificToNumber #-}
170−
171180parseRealFloat :: RealFloat a => String -> Value -> Parser a
172−parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
173−parseRealFloat _ Null = pure (0/0)
174−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)
175184{-# INLINE parseRealFloat #-}
176185
186+parseIntegralFromScientific :: forall a. Integral a => Scientific -> Parser a
187+parseIntegralFromScientific s =
188+ case Scientific.floatingOrInteger s :: Either Double a of
189+ Right x -> pure x
190+ Left _ -> fail $ "unexpected floating number " ++ show s
191+{-# INLINE parseIntegralFromScientific #-}
192+
177193parseIntegral :: Integral a => String -> Value -> Parser a
178−parseIntegral expected = withScientific expected $ pure . truncate
194+parseIntegral name =
195+ prependContext name . withBoundedScientific' parseIntegralFromScientific
179196{-# INLINE parseIntegral #-}
180197
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)
201+ pure
202+ (Scientific.toBoundedInteger s)
203+{-# INLINE parseBoundedIntegralFromScientific #-}
204+
205+parseBoundedIntegral :: (Bounded a, Integral a) => String -> Value -> Parser a
206+parseBoundedIntegral name =
207+ prependContext name . withScientific' parseBoundedIntegralFromScientific
208+{-# INLINE parseBoundedIntegral #-}
209+
181210parseScientificText :: Text -> Parser Scientific
182211parseScientificText
183212 = either fail pure
184213 . A.parseOnly (A.scientific <* A.endOfInput)
185214 . T.encodeUtf8
186215
187−parseIntegralText :: Integral a => Text -> Parser a
188−parseIntegralText t = truncate <$> parseScientificText t
216+parseIntegralText :: Integral a => String -> Text -> Parser a
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)
225+{-# INLINE parseIntegralText #-}
226+
227+parseBoundedIntegralText :: (Bounded a, Integral a) => String -> Text -> Parser a
228+parseBoundedIntegralText name t =
229+ prependContext name $
230+ parseScientificText t >>= parseBoundedIntegralFromScientific
189231
190232parseOptionalFieldWith :: (Value -> Parser (Maybe a))
191233 -> Object -> Text -> Parser (Maybe a)
@@ -204,16 +246,21 @@ class GFromJSON arity f where
204246 -- | This method (applied to 'defaultOptions') is used as the
205247 -- default generic implementation of 'parseJSON' (if the @arity@ is 'Zero')
206248 -- or 'liftParseJSON' (if the @arity@ is 'One').
207− gParseJSON :: Options -> Proxy arity
208− -> (Value -> Parser a) -> (Value -> Parser [a])
209− -> Value -> Parser (f a)
249+ gParseJSON :: Options -> FromArgs arity a -> Value -> Parser (f a)
250+
251+-- | A 'FromArgs' value either stores nothing (for 'FromJSON') or it stores the
252+-- two function arguments that decode occurrences of the type parameter (for
253+-- 'FromJSON1').
254+data FromArgs arity a where
255+ NoFromArgs :: FromArgs Zero a
256+ From1Args :: (Value -> Parser a) -> (Value -> Parser [a]) -> FromArgs One a
210257
211258-- | A configurable generic JSON decoder. This function applied to
212259-- 'defaultOptions' is used as the default for 'parseJSON' when the
213260-- type is an instance of 'Generic'.
214261genericParseJSON :: (Generic a, GFromJSON Zero (Rep a))
215262 => Options -> Value -> Parser a
216−genericParseJSON opts = fmap to . gParseJSON opts proxyZero undefined undefined
263+genericParseJSON opts = fmap to . gParseJSON opts NoFromArgs
217264
218265-- | A configurable generic JSON decoder. This function applied to
219266-- 'defaultOptions' is used as the default for 'liftParseJSON' when the
@@ -221,7 +268,7 @@ genericParseJSON opts = fmap to . gParseJSON opts proxyZero undefined undefined
221268genericLiftParseJSON :: (Generic1 f, GFromJSON One (Rep1 f))
222269 => Options -> (Value -> Parser a) -> (Value -> Parser [a])
223270 -> Value -> Parser (f a)
224−genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
271+genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
225272
226273-------------------------------------------------------------------------------
227274-- Class
@@ -240,14 +287,21 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
240287--
241288-- The basic ways to signal a failed conversion are as follows:
242289--
243−-- * '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;
244292--
245−-- * 'fail' yields a custom error message
293+-- * 'Control.Applicative.empty' (or 'Control.Monad.mzero') is uninformative:
294+-- use it when the error is meant to be caught by some @('<|>')@;
246295--
247−-- * 'typeMismatch' produces an informative message for cases when the
248−-- value encountered is not of the expected type
296+-- * 'typeMismatch' can be used to report a failure when the encountered value
297+-- is not of the expected JSON type; 'unexpected' is an appropriate alternative
298+-- when more than one type may be expected, or to keep the expected type
299+-- implicit.
249300--
250−-- An example type and instance:
301+-- 'prependFailure' (or 'modifyFailure') add more information to a parser's
302+-- error messages.
303+--
304+-- An example type and instance using 'typeMismatch' and 'prependFailure':
251305--
252306-- @
253307-- \-- Allow ourselves to write 'Text' literals.
@@ -255,15 +309,30 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
255309--
256310-- data Coord = Coord { x :: Double, y :: Double }
257311--
258−-- instance FromJSON Coord where
259−-- parseJSON ('Object' v) = Coord '<$>'
260−-- v '.:' \"x\" '<*>'
261−-- v '.:' \"y\"
312+-- instance 'FromJSON' Coord where
313+-- 'parseJSON' ('Object' v) = Coord
314+-- '<$>' v '.:' \"x\"
315+-- '<*>' v '.:' \"y\"
316+--
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+-- @
262324--
263−-- \-- We do not expect a non-'Object' value here.
264−-- \-- We could use 'mzero' to fail, but 'typeMismatch'
265−-- \-- gives a much more informative error message.
266−-- parseJSON invalid = 'typeMismatch' \"Coord\" invalid
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\"
267336-- @
268337--
269338-- Instead of manually writing your 'FromJSON' instance, there are two options
@@ -271,7 +340,7 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
271340--
272341-- * "Data.Aeson.TH" provides Template Haskell functions which will derive an
273342-- instance at compile time. The generated instance is optimized for your type
274−-- so will probably be more efficient than the following two options:
343+-- so it will probably be more efficient than the following option.
275344--
276345-- * The compiler can provide a default generic implementation for
277346-- 'parseJSON'.
@@ -289,18 +358,21 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
289358--
290359-- data Coord = Coord { x :: Double, y :: Double } deriving 'Generic'
291360--
292−-- instance FromJSON Coord
361+-- instance 'FromJSON' Coord
293362-- @
294363--
295−-- If @DefaultSignatures@ doesn't give exactly the results you want,
296−-- you can customize the generic decoding with only a tiny amount of
297−-- 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:
298367--
299368-- @
300−-- instance FromJSON Coord where
301−-- parseJSON = 'genericParseJSON' 'defaultOptions'
369+-- customOptions = 'defaultOptions'
370+-- { 'fieldLabelModifier' = 'map' 'Data.Char.toUpper'
371+-- }
372+--
373+-- instance 'FromJSON' Coord where
374+-- 'parseJSON' = 'genericParseJSON' customOptions
302375-- @
303−
304376class FromJSON a where
305377 parseJSON :: Value -> Parser a
306378
@@ -308,61 +380,89 @@ class FromJSON a where
308380 parseJSON = genericParseJSON defaultOptions
309381
310382 parseJSONList :: Value -> Parser [a]
311− parseJSONList (Array a)
312− = sequence
313− . zipWith (parseIndexedJSON parseJSON) [0..]
383+ parseJSONList = withArray "[]" $ \a ->
384+ zipWithM (parseIndexedJSON parseJSON) [0..]
314385 . V.toList
315386 $ a
316387
317− parseJSONList v = typeMismatch "[a]" v
318−
319388-------------------------------------------------------------------------------
320389-- Classes and types for map keys
321390-------------------------------------------------------------------------------
322391
392+-- | Read the docs for 'ToJSONKey' first. This class is a conversion
393+-- in the opposite direction. If you have a newtype wrapper around 'Text',
394+-- the recommended way to define instances is with generalized newtype deriving:
395+--
396+-- > newtype SomeId = SomeId { getSomeId :: Text }
397+-- > deriving (Eq,Ord,Hashable,FromJSONKey)
398+--
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+-- @
323409class FromJSONKey a where
410+ -- | Strategy for parsing the key of a map-like container.
324411 fromJSONKey :: FromJSONKeyFunction a
325412 default fromJSONKey :: FromJSON a => FromJSONKeyFunction a
326413 fromJSONKey = FromJSONKeyValue parseJSON
327414
415+ -- | This is similar in spirit to the 'readList' method of 'Read'.
416+ -- It makes it possible to give 'String' keys special treatment
417+ -- without using @OverlappingInstances@. End users should always
418+ -- be able to use the default implementation of this method.
328419 fromJSONKeyList :: FromJSONKeyFunction [a]
329420 default fromJSONKeyList :: FromJSON a => FromJSONKeyFunction [a]
330421 fromJSONKeyList = FromJSONKeyValue parseJSON
331422
332−-- | With GHC 7.8 + we carry around 'Coercible Text a' dictionary,
333−-- to have even some amount of safety net.
334−-- Unfortunately we cannot enforce that 'Hashable' instance agree on the type level
423+-- | With GHC 7.8+ we carry around @'Coercible' 'Text' a@ dictionary,
424+-- to give us an assurance that the program will not segfault.
425+-- Unfortunately we cannot enforce that the 'Eq' instances or the
426+-- 'Hashable' instances for 'Text' and @a@ agree.
335427--
336−-- ATM this type is intentionally not exported. FromJSONKeyFunction can be inspected,
337−-- but cannot be constructed.
428+-- At the moment this type is intentionally not exported. 'FromJSONKeyFunction'
429+-- can be inspected, but cannot be constructed.
338430data CoerceText a where
339−#if HAS_COERCIBLE
340431 CoerceText :: Coercible Text a => CoerceText a
341−#else
342− CoerceText :: CoerceText a
343−#endif
344432
433+-- | This type is related to 'ToJSONKeyFunction'. If 'FromJSONKeyValue' is used in the
434+-- 'FromJSONKey' instance, then 'ToJSONKeyValue' should be used in the 'ToJSONKey'
435+-- instance. The other three data constructors for this type all correspond to
436+-- 'ToJSONKeyText'. Strictly speaking, 'FromJSONKeyTextParser' is more powerful than
437+-- 'FromJSONKeyText', which is in turn more powerful than 'FromJSONKeyCoerce'.
438+-- For performance reasons, these exist as three options instead of one.
345439data FromJSONKeyFunction a
346440 = FromJSONKeyCoerce !(CoerceText a)
441+ -- ^ uses 'coerce' ('unsafeCoerce' in older GHCs)
347442 | FromJSONKeyText !(Text -> a)
443+ -- ^ conversion from 'Text' that always succeeds
348444 | FromJSONKeyTextParser !(Text -> Parser a)
445+ -- ^ conversion from 'Text' that may fail
349446 | FromJSONKeyValue !(Value -> Parser a)
447+ -- ^ conversion for non-textual keys
350448
449+-- | Only law abiding up to interpretation
351450instance Functor FromJSONKeyFunction where
352− fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce')
451+ fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce)
353452 fmap h (FromJSONKeyText f) = FromJSONKeyText (h . f)
354453 fmap h (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap h . f)
355454 fmap h (FromJSONKeyValue f) = FromJSONKeyValue (fmap h . f)
356455
357456-- | Construct 'FromJSONKeyFunction' for types coercible from 'Text'. This
358457-- conversion is still unsafe, as 'Hashable' and 'Eq' instances of @a@ should be
458+-- compatible with 'Text' i.e. hash values should be equal for wrapped values as well.
459+-- This property will always be maintained if the 'Hashable' and 'Eq' instances
460+-- are derived with generalized newtype deriving.
359461-- compatible with 'Text' i.e. hash values be equal for wrapped values as well.
360462--
361463-- On pre GHC 7.8 this is unconstrainted function.
362464fromJSONKeyCoerce ::
363−#if HAS_COERCIBLE
364465 Coercible Text a =>
365−#endif
366466 FromJSONKeyFunction a
367467fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
368468
@@ -370,60 +470,91 @@ fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
370470--
371471-- See note on 'fromJSONKeyCoerce'.
372472coerceFromJSONKeyFunction ::
373−#if HAS_COERCIBLE
374473 Coercible a b =>
375−#endif
376474 FromJSONKeyFunction a -> FromJSONKeyFunction b
377−#if HAS_COERCIBLE
378475coerceFromJSONKeyFunction = coerce
379−#else
380−coerceFromJSONKeyFunction (FromJSONKeyCoerce CoerceText) = FromJSONKeyCoerce CoerceText
381−coerceFromJSONKeyFunction (FromJSONKeyText f) = FromJSONKeyText (coerce' . f)
382−coerceFromJSONKeyFunction (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap coerce' . f)
383−coerceFromJSONKeyFunction (FromJSONKeyValue f) = FromJSONKeyValue (fmap coerce' . f)
384−#endif
385476
386477{-# RULES
387478 "FromJSONKeyCoerce: fmap id" forall (x :: FromJSONKeyFunction a).
388479 fmap id x = x
389480 #-}
390−#if HAS_COERCIBLE
391481{-# RULES
392482 "FromJSONKeyCoerce: fmap coerce" forall x .
393483 fmap coerce x = coerceFromJSONKeyFunction x
394484 #-}
395−#endif
396485
397486-- | Same as 'fmap'. Provided for the consistency with 'ToJSONKeyFunction'.
398487mapFromJSONKeyFunction :: (a -> b) -> FromJSONKeyFunction a -> FromJSONKeyFunction b
399488mapFromJSONKeyFunction = fmap
400489
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+
401519-------------------------------------------------------------------------------
402520-- Functions needed for documentation
403521-------------------------------------------------------------------------------
404522
405523-- | Fail parsing due to a type mismatch, with a descriptive message.
406524--
407−-- Example usage:
525+-- The following wrappers should generally be prefered:
526+-- 'withObject', 'withArray', 'withText', 'withBool'.
408527--
409−-- @
410−-- instance FromJSON Coord where
411−-- parseJSON ('Object' v) = {- type matches, life is good -}
412−-- parseJSON wat = 'typeMismatch' \"Coord\" wat
413−-- @
414−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\"@).
415535 -> Value -- ^ The actual value encountered.
416536 -> Parser a
417537typeMismatch expected actual =
418− fail $ "expected " ++ expected ++ ", encountered " ++ name
419− where
420− name = case actual of
421− Object _ -> "Object"
422− Array _ -> "Array"
423− String _ -> "String"
424− Number _ -> "Number"
425− Bool _ -> "Boolean"
426− 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"
427558
428559-------------------------------------------------------------------------------
429560-- Lifings of FromJSON and ToJSON to unary and binary type constructors
@@ -436,7 +567,7 @@ typeMismatch expected actual =
436567--
437568-- * "Data.Aeson.TH" provides Template Haskell functions which will derive an
438569-- instance at compile time. The generated instance is optimized for your type
439−-- so will probably be more efficient than the following two options:
570+-- so it will probably be more efficient than the following option.
440571--
441572-- * The compiler can provide a default generic implementation for
442573-- 'liftParseJSON'.
@@ -454,16 +585,20 @@ typeMismatch expected actual =
454585--
455586-- data Pair a b = Pair { pairFst :: a, pairSnd :: b } deriving 'Generic1'
456587--
457−-- instance FromJSON a => FromJSON1 (Pair a)
588+-- instance 'FromJSON' a => 'FromJSON1' (Pair a)
458589-- @
459590--
460−-- If @DefaultSignatures@ doesn't give exactly the results you want,
591+-- If the default implementation doesn't give exactly the results you want,
461592-- you can customize the generic decoding with only a tiny amount of
462593-- effort, using 'genericLiftParseJSON' with your preferred 'Options':
463594--
464595-- @
465−-- instance FromJSON a => FromJSON1 (Pair a) where
466−-- 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
467602-- @
468603class FromJSON1 f where
469604 liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (f a)
@@ -500,9 +635,8 @@ class FromJSON2 f where
500635 -> (Value -> Parser b)
501636 -> (Value -> Parser [b])
502637 -> Value -> Parser [f a b]
503− liftParseJSONList2 fa ga fb gb v = case v of
504− Array vals -> fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
505− _ -> typeMismatch "[a]" v
638+ liftParseJSONList2 fa ga fb gb = withArray "[]" $ \vals ->
639+ fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
506640
507641-- | Lift the standard 'parseJSON' function through the type constructor.
508642parseJSON2 :: (FromJSON2 f, FromJSON a, FromJSON b) => Value -> Parser (f a b)
@@ -513,9 +647,10 @@ parseJSON2 = liftParseJSON2 parseJSON parseJSONList parseJSON parseJSONList
513647-- List functions
514648-------------------------------------------------------------------------------
515649
650+-- | Helper function to use with 'liftParseJSON'. See 'Data.Aeson.ToJSON.listEncoding'.
516651listParser :: (Value -> Parser a) -> Value -> Parser [a]
517652listParser f (Array xs) = fmap V.toList (V.mapM f xs)
518−listParser _ v = typeMismatch "[a]" v
653+listParser _ v = typeMismatch "Array" v
519654{-# INLINE listParser #-}
520655
521656-------------------------------------------------------------------------------
@@ -533,48 +668,139 @@ instance (FromJSON a) => FromJSON [a] where
533668-- Functions
534669-------------------------------------------------------------------------------
535670
536−-- | @withObject expected f value@ applies @f@ to the 'Object' when @value@ is an @Object@
537−-- 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"
538686withObject :: String -> (Object -> Parser a) -> Value -> Parser a
539−withObject _ f (Object obj) = f obj
540−withObject expected _ v = typeMismatch expected v
687+withObject _ f (Object obj) = f obj
688+withObject name _ v = prependContext name (typeMismatch "Object" v)
541689{-# INLINE withObject #-}
542690
543−-- | @withText expected f value@ applies @f@ to the 'Text' when @value@ is a @String@
544−-- 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"
545698withText :: String -> (Text -> Parser a) -> Value -> Parser a
546−withText _ f (String txt) = f txt
547−withText expected _ v = typeMismatch expected v
699+withText _ f (String txt) = f txt
700+withText name _ v = prependContext name (typeMismatch "String" v)
548701{-# INLINE withText #-}
549702
550−-- | @withArray expected f value@ applies @f@ to the 'Array' when @value@ is an @Array@
551−-- 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"
552710withArray :: String -> (Array -> Parser a) -> Value -> Parser a
553−withArray _ f (Array arr) = f arr
554−withArray expected _ v = typeMismatch expected v
711+withArray _ f (Array arr) = f arr
712+withArray name _ v = prependContext name (typeMismatch "Array" v)
555713{-# INLINE withArray #-}
556714
557−-- | @withNumber expected f value@ applies @f@ to the 'Number' when @value@ is a 'Number'.
558−-- and fails using @'typeMismatch' expected@ otherwise.
559−withNumber :: String -> (Number -> Parser a) -> Value -> Parser a
560−withNumber expected f = withScientific expected (f . scientificToNumber)
561−{-# INLINE withNumber #-}
562−{-# DEPRECATED withNumber "Use withScientific instead" #-}
563−
564−-- | @withScientific expected f value@ applies @f@ to the 'Scientific' number when @value@ is a 'Number'.
565−-- 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"
566728withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
567−withScientific _ f (Number scientific) = f scientific
568−withScientific expected _ v = typeMismatch expected v
729+withScientific _ f (Number scientific) = f scientific
730+withScientific name _ v = prependContext name (typeMismatch "Number" v)
569731{-# INLINE withScientific #-}
570732
571−-- | @withBool expected f value@ applies @f@ to the 'Bool' when @value@ is a @Bool@
572−-- 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"
573789withBool :: String -> (Bool -> Parser a) -> Value -> Parser a
574−withBool _ f (Bool arr) = f arr
575−withBool expected _ v = typeMismatch expected v
790+withBool _ f (Bool arr) = f arr
791+withBool name _ v = prependContext name (typeMismatch "Boolean" v)
576792{-# INLINE withBool #-}
577793
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+
578804-- | Convert a value from JSON, failing if the types do not match.
579805fromJSON :: (FromJSON a) => Value -> Result a
580806fromJSON = parse parseJSON
@@ -593,32 +819,68 @@ ifromJSON = iparse parseJSON
593819-- in an object for it to be valid. If the key and value are
594820-- optional, use '.:?' instead.
595821(.:) :: (FromJSON a) => Object -> Text -> Parser a
596−obj .: key = case H.lookup key obj of
597− Nothing -> fail $ "key " ++ show key ++ " not present"
598− Just v -> parseJSON v <?> Key key
822+(.:) = explicitParseField parseJSON
599823{-# INLINE (.:) #-}
600824
601−-- | Retrieve the value associated with the given key of an 'Object'.
602−-- The result is 'Nothing' if the key is not present, or 'empty' if
603−-- 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.
604828--
605829-- This accessor is most useful if the key and value can be absent
606830-- from an object without affecting its validity. If the key and
607831-- value are mandatory, use '.:' instead.
608832(.:?) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
609−obj .:? key = case H.lookup key obj of
610− Nothing -> pure Nothing
611− Just v -> parseJSON v <?> Key key
833+(.:?) = explicitParseFieldMaybe parseJSON
612834{-# INLINE (.:?) #-}
613835
614−-- | Like '.:?', but the resulting parser will fail,
615−-- 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'.
616842(.:!) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
617−obj .:! key = case H.lookup key obj of
618− Nothing -> pure Nothing
619− Just v -> Just <$> parseJSON v <?> Key key
843+(.:!) = explicitParseFieldMaybe' parseJSON
620844{-# INLINE (.:!) #-}
621845
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 <$> p v <?> Key key
882+{-# INLINE explicitParseFieldMaybe' #-}
883+
622884-- | Helper for use in combination with '.:?' to provide default
623885-- values for optional JSON object fields.
624886--
@@ -641,317 +903,554 @@ pmval .!= val = fromMaybe val <$> pmval
641903-- Generic parseJSON
642904-------------------------------------------------------------------------------
643905
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+
644911instance OVERLAPPABLE_ (GFromJSON arity a) => GFromJSON arity (M1 i c a) where
645912 -- Meta-information, which is not handled elsewhere, is just added to the
646913 -- parsed value:
647− gParseJSON opts pa pj pjl = fmap M1 . gParseJSON opts pa pj pjl
914+ gParseJSON opts fargs = fmap M1 . gParseJSON opts fargs
915+
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
648946
649947instance (FromJSON a) => GFromJSON arity (K1 i a) where
650948 -- Constant values are decoded using their FromJSON instance:
651− gParseJSON _opts _ _ _ = fmap K1 . parseJSON
949+ gParseJSON _opts _ = fmap K1 . parseJSON
652950
653951instance GFromJSON One Par1 where
654952 -- Direct occurrences of the last type parameter are decoded with the
655953 -- function passed in as an argument:
656− gParseJSON _opts _ pj _ = fmap Par1 . pj
954+ gParseJSON _opts (From1Args pj _) = fmap Par1 . pj
657955
658956instance (FromJSON1 f) => GFromJSON One (Rec1 f) where
659957 -- Recursive occurrences of the last type parameter are decoded using their
660958 -- FromJSON1 instance:
661− gParseJSON _opts _ pj pjl = fmap Rec1 . liftParseJSON pj pjl
662−
663−instance GFromJSON arity U1 where
664− -- Empty constructors are expected to be encoded as an empty array:
665− gParseJSON _opts _ _ _ v
666− | isEmptyArray v = pure U1
667− | otherwise = typeMismatch "unit constructor (U1)" v
668−
669−instance (ConsFromJSON arity a) => GFromJSON arity (C1 c a) where
670− -- Constructors need to be decoded differently depending on whether they're
671− -- a record or not. This distinction is made by consParseJSON:
672− gParseJSON opts pa pj pjl = fmap M1 . consParseJSON opts pa pj pjl
673−
674−instance ( FromProduct arity a, FromProduct arity b
675− , ProductSize a, ProductSize b
676− ) => GFromJSON arity (a :*: b) where
677− -- Products are expected to be encoded to an array. Here we check whether we
678− -- got an array of the same size as the product, then parse each of the
679− -- product's elements using parseProduct:
680− gParseJSON opts pa pj pjl = withArray "product (:*:)" $ \arr ->
681− let lenArray = V.length arr
682− lenProduct = (unTagged2 :: Tagged2 (a :*: b) Int -> Int)
683− productSize in
684− if lenArray == lenProduct
685− then parseProduct opts pa arr 0 lenProduct pj pjl
686− else fail $ "When expecting a product of " ++ show lenProduct ++
687− " values, encountered an Array of " ++ show lenArray ++
688− " elements instead"
689−
690−instance ( AllNullary (a :+: b) allNullary
691− , ParseSum arity (a :+: b) allNullary
692− ) => GFromJSON arity (a :+: b) where
693− -- If all constructors of a sum datatype are nullary and the
694− -- 'allNullaryToStringTag' option is set they are expected to be
695− -- encoded as strings. This distinction is made by 'parseSum':
696− gParseJSON opts pa pj pjl =
697− (unTagged :: Tagged allNullary (Parser ((a :+: b) d)) ->
698− (Parser ((a :+: b) d)))
699− . parseSum opts pa pj pjl
959+ gParseJSON _opts (From1Args pj pjl) = fmap Rec1 . liftParseJSON pj pjl
700960
701961instance (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) where
702962 -- If an occurrence of the last type parameter is nested inside two
703963 -- composed types, it is decoded by using the outermost type's FromJSON1
704964 -- instance to generically decode the innermost type:
705− gParseJSON opts pa pj pjl =
706− let gpj = gParseJSON opts pa pj pjl in
707− fmap Comp1 . liftParseJSON gpj (listParser gpj)
965+ gParseJSON opts fargs =
966+ let gpj = gParseJSON opts fargs in
967+ fmap Comp1 . liftParseJSON gpj (listParser gpj)
968+
969+--------------------------------------------------------------------------------
970+
971+instance (GFromJSON' arity a, Datatype d) => GFromJSON arity (D1 d a) where
972+ -- Meta-information, which is not handled elsewhere, is just added to the
973+ -- parsed value:
974+ gParseJSON opts fargs = fmap M1 . gParseJSON' (tname :* opts :* fargs)
975+ where
976+ tname = moduleName proxy ++ "." ++ datatypeName proxy
977+ proxy = undefined :: M1 _i d _f _p
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
7081013
7091014--------------------------------------------------------------------------------
7101015
7111016class ParseSum arity f allNullary where
712− parseSum :: Options -> Proxy arity
713− -> (Value -> Parser a) -> (Value -> Parser [a])
714− -> Value -> Tagged allNullary (Parser (f a))
715−
716−instance ( SumFromString (a :+: b)
717− , FromPair arity (a :+: b)
718− , FromTaggedObject arity (a :+: b)
719− ) => ParseSum arity (a :+: b) True where
720− parseSum opts pa pj pjl
721− | allNullaryToStringTag opts = Tagged . parseAllNullarySum opts
722− | otherwise = Tagged . parseNonAllNullarySum opts pa pj pjl
723−
724−instance ( FromPair arity (a :+: b)
725− , FromTaggedObject arity (a :+: b)
726− ) => ParseSum arity (a :+: b) False where
727− parseSum opts pa pj pjl = Tagged . parseNonAllNullarySum opts pa pj pjl
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
7281037
7291038--------------------------------------------------------------------------------
7301039
731−parseAllNullarySum :: SumFromString f => Options -> Value -> Parser (f a)
732−parseAllNullarySum opts = withText "Text" $ \key ->
733− maybe (notFound key) return $
734− 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])
7351062
7361063class SumFromString f where
737− parseSumFromString :: Options -> Text -> Maybe (f a)
1064+ parseSumFromString :: (String -> String) -> Text -> Maybe (f a)
7381065
7391066instance (SumFromString a, SumFromString b) => SumFromString (a :+: b) where
7401067 parseSumFromString opts key = (L1 <$> parseSumFromString opts key) <|>
7411068 (R1 <$> parseSumFromString opts key)
7421069
7431070instance (Constructor c) => SumFromString (C1 c U1) where
744− parseSumFromString opts key | key == name = Just $ M1 U1
745− | otherwise = Nothing
746− where
747− name = pack $ constructorTagModifier opts $
748− 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)
7491076
750−--------------------------------------------------------------------------------
1077+-- For genericFromJSONKey
1078+instance SumFromString a => SumFromString (D1 d a) where
1079+ parseSumFromString modifier key = M1 <$> parseSumFromString modifier key
1080+
1081+-- | List of all constructor tags.
1082+constructorTags :: ConstructorNames a => (String -> t) -> Tagged2 a [t]
1083+constructorTags modifier =
1084+ fmap DList.toList (constructorNames' modifier)
1085+
1086+-- | List of all constructor names of an ADT, after a given conversion
1087+-- function. (Better inlining.)
1088+class ConstructorNames a where
1089+ constructorNames' :: (String -> t) -> Tagged2 a (DList.DList t)
1090+
1091+instance (ConstructorNames a, ConstructorNames b) => ConstructorNames (a :+: b) where
1092+ constructorNames' = liftA2 append constructorNames' constructorNames'
1093+ where
1094+ append
1095+ :: Tagged2 a (DList.DList t)
1096+ -> Tagged2 b (DList.DList t)
1097+ -> Tagged2 (a :+: b) (DList.DList t)
1098+ append (Tagged2 xs) (Tagged2 ys) = Tagged2 (DList.append xs ys)
1099+
1100+instance Constructor c => ConstructorNames (C1 c a) where
1101+ constructorNames' f = Tagged2 (pure (f cname))
1102+ where
1103+ cname = conName (undefined :: M1 _i c _f _p)
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
7511111
752−parseNonAllNullarySum :: ( FromPair arity (a :+: b)
753− , FromTaggedObject arity (a :+: b)
754− ) => Options -> Proxy arity
755− -> (Value -> Parser c) -> (Value -> Parser [c])
756− -> Value -> Parser ((a :+: b) c)
757−parseNonAllNullarySum opts pa pj pjl =
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 :* _) =
7581121 case sumEncoding opts of
7591122 TaggedObject{..} ->
760− withObject "Object" $ \obj -> do
761− tag <- obj .: pack tagFieldName
762− fromMaybe (notFound tag) $
763− parseFromTaggedObject opts pa contentsFieldName obj pj pjl 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])
7641133
7651134 ObjectWithSingleField ->
766− withObject "Object" $ \obj ->
767− case H.toList obj of
768− [pair@(tag, _)] -> fromMaybe (notFound tag) $
769− parsePair opts pa pj pjl pair
770− _ -> 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
7711145
7721146 TwoElemArray ->
773− withArray "Array" $ \arr ->
774− if V.length arr == 2
775− then case V.unsafeIndex arr 0 of
776− String tag -> fromMaybe (notFound tag) $
777− parsePair opts pa pj pjl (tag, V.unsafeIndex arr 1)
778− _ -> fail "First element is not a String"
779− 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
1161+
1162+ UntaggedValue -> parseUntaggedValue p
1163+ where
1164+ failWith_ = failWithCTags tname (constructorTagModifier opts)
7801165
7811166--------------------------------------------------------------------------------
7821167
7831168class FromTaggedObject arity f where
784− parseFromTaggedObject :: Options -> Proxy arity
785− -> String -> Object
786− -> (Value -> Parser a) -> (Value -> Parser [a])
787− -> 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))
7881175
7891176instance ( FromTaggedObject arity a, FromTaggedObject arity b) =>
7901177 FromTaggedObject arity (a :+: b) where
791− parseFromTaggedObject opts pa contentsFieldName obj pj pjl tag =
792− (fmap L1 <$> parseFromTaggedObject opts pa contentsFieldName obj pj pjl tag) <|>
793− (fmap R1 <$> parseFromTaggedObject opts pa contentsFieldName obj pj pjl tag)
1178+ parseFromTaggedObject p obj =
1179+ (fmap L1 <$> parseFromTaggedObject p obj) <|>
1180+ (fmap R1 <$> parseFromTaggedObject p obj)
7941181
795−instance ( FromTaggedObject' arity f
1182+instance ( IsRecord f isRecord
1183+ , FromTaggedObject' arity f isRecord
7961184 , Constructor c
7971185 ) => FromTaggedObject arity (C1 c f) where
798− parseFromTaggedObject opts pa contentsFieldName obj pj pjl tag
799− | tag == name = Just $ M1 <$> parseFromTaggedObject'
800− opts pa contentsFieldName pj pjl obj
801− | otherwise = Nothing
802− where
803− name = pack $ constructorTagModifier opts $
804− 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)
8051195
8061196--------------------------------------------------------------------------------
8071197
808−class FromTaggedObject' arity f where
809− parseFromTaggedObject' :: Options -> Proxy arity -> String
810− -> (Value -> Parser a) -> (Value -> Parser [a])
811− -> Object -> Parser (f a)
812−
813−class FromTaggedObject'' arity f isRecord where
814− parseFromTaggedObject'' :: Options -> Proxy arity -> String
815− -> (Value -> Parser a) -> (Value -> Parser [a])
816− -> Object -> Tagged isRecord (Parser (f a))
817−
818−instance ( IsRecord f isRecord
819− , FromTaggedObject'' arity f isRecord
820− ) => FromTaggedObject' arity f where
821− parseFromTaggedObject' opts pa contentsFieldName pj pjl =
822− (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a)) .
823− parseFromTaggedObject'' opts pa contentsFieldName pj pjl
824−
825−instance (FromRecord arity f) => FromTaggedObject'' arity f True where
826− parseFromTaggedObject'' opts pa _ pj pjl =
827− Tagged . parseRecord opts pa Nothing pj pjl
828−
829−instance (GFromJSON arity f) => FromTaggedObject'' arity f False where
830− parseFromTaggedObject'' opts pa contentsFieldName pj pjl = Tagged .
831− (gParseJSON opts pa pj pjl <=< (.: 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
8321216
833−instance OVERLAPPING_ FromTaggedObject'' arity U1 False where
834− 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)
8351220
8361221--------------------------------------------------------------------------------
8371222
1223+-- | Constructors need to be decoded differently depending on whether they're
1224+-- a record or not. This distinction is made by 'ConsParseJSON'.
8381225class ConsFromJSON arity f where
839− consParseJSON :: Options -> Proxy arity
840− -> (Value -> Parser a) -> (Value -> Parser [a])
841− -> Value -> Parser (f a)
1226+ consParseJSON
1227+ :: ConName :* TypeName :* Options :* FromArgs arity a
1228+ -> Value -> Parser (f a)
8421229
8431230class ConsFromJSON' arity f isRecord where
844− consParseJSON' :: Options -> Proxy arity
845− -> (Maybe Text) -- ^ A dummy label
846− -- (Nothing to use proper label)
847− -> (Value -> Parser a) -> (Value -> Parser [a])
848− -> Value -> Tagged isRecord (Parser (f a))
1231+ consParseJSON'
1232+ :: ConName :* TypeName :* Options :* FromArgs arity a
1233+ -> Value -> Tagged isRecord (Parser (f a))
8491234
8501235instance ( IsRecord f isRecord
8511236 , ConsFromJSON' arity f isRecord
8521237 ) => ConsFromJSON arity f where
853− consParseJSON opts pa pj pjl v = let
854− (v2,lab) = case (unwrapUnaryRecords opts,isUnary (undefined :: f a)) of
855− -- use a dummy object with a dummy label
856− (True,True) -> ((object [(pack "dummy",v)]),Just $ pack "dummy")
857− _ ->(v,Nothing)
858− in (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
859− $ consParseJSON' opts pa lab pj pjl v2
860−
1238+ consParseJSON p =
1239+ (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
1240+ . consParseJSON' p
1241+
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))
1248+
1249+instance RecordFromJSON arity f => ConsFromJSON' arity f True where
1250+ consParseJSON' p@(cname :* tname :* _) =
1251+ Tagged . withObject (showCons cname tname) (recordParseJSON (False :* p))
1252+
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)
8611265
862−instance (FromRecord arity f) => ConsFromJSON' arity f True where
863− consParseJSON' opts pa mlab pj pjl = Tagged . (withObject "record (:*:)"
864− $ parseRecord opts pa mlab pj pjl)
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
8651270
866−instance (GFromJSON arity f) => ConsFromJSON' arity f False where
867− consParseJSON' opts pa _ pj pjl = Tagged . gParseJSON opts pa pj pjl
1271+instance (ProductFromJSON arity f, ProductSize f
1272+ ) => ConsFromJSON' arity f False where
1273+ consParseJSON' p = Tagged . productParseJSON0 p
8681274
8691275--------------------------------------------------------------------------------
8701276
871−class FromRecord arity f where
872− parseRecord :: Options -> Proxy arity
873− -> (Maybe Text) -- ^ A dummy label
874− -- (Nothing to use proper label)
875− -> (Value -> Parser a) -> (Value -> Parser [a])
876− -> Object -> Parser (f a)
877−
878−instance ( FromRecord arity a
879− , FromRecord arity b
880− ) => FromRecord arity (a :*: b) where
881− parseRecord opts pa _ pj pjl obj =
882− (:*:) <$> parseRecord opts pa Nothing pj pjl obj
883− <*> parseRecord opts pa Nothing pj pjl obj
884−
885−instance ( Selector s
886− , GFromJSON arity a
887− ) => FromRecord arity (S1 s a) where
888− parseRecord opts pa lab pj pjl =
889− (<?> Key label) . gParseJSON opts pa pj pjl <=< (.: label)
890− where
891− label = fromMaybe defLabel lab
892− defLabel = pack . fieldLabelModifier opts $
893− selName (undefined :: t s a p)
894−
895−instance OVERLAPPING_ (Selector s, FromJSON a) =>
896− FromRecord arity (S1 s (K1 i (Maybe a))) where
897− parseRecord _ _ (Just lab) _ _ obj = (M1 . K1) <$> obj .:? lab
898− parseRecord opts _ Nothing _ _ obj = (M1 . K1) <$> 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
8991298 where
900− label = fieldLabelModifier opts $
901− 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))
9021346
9031347--------------------------------------------------------------------------------
9041348
905−class FromProduct arity f where
906− parseProduct :: Options -> Proxy arity
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
9071371 -> Array -> Int -> Int
908− -> (Value -> Parser a) -> (Value -> Parser [a])
9091372 -> Parser (f a)
9101373
911−instance ( FromProduct arity a
912− , FromProduct arity b
913− ) => FromProduct arity (a :*: b) where
914− parseProduct opts pa arr ix len pj pjl =
915− (:*:) <$> parseProduct opts pa arr ix lenL pj pjl
916− <*> parseProduct opts pa arr ixR lenR pj pjl
1374+instance ( ProductFromJSON arity a
1375+ , ProductFromJSON arity b
1376+ ) => ProductFromJSON arity (a :*: b) where
1377+ productParseJSON p arr ix len =
1378+ (:*:) <$> productParseJSON p arr ix lenL
1379+ <*> productParseJSON p arr ixR lenR
9171380 where
9181381 lenL = len `unsafeShiftR` 1
9191382 ixR = ix + lenL
9201383 lenR = len - lenL
9211384
922−instance (GFromJSON arity a) => FromProduct arity (S1 s a) where
923− parseProduct opts pa arr ix _ pj pjl =
924− gParseJSON opts pa pj pjl $ V.unsafeIndex arr ix
1385+instance (GFromJSON arity a) => ProductFromJSON arity (S1 s a) where
1386+ productParseJSON (_ :* _ :* opts :* fargs) arr ix _ =
1387+ M1 <$> gParseJSON opts fargs (V.unsafeIndex arr ix) <?> Index ix
9251388
9261389--------------------------------------------------------------------------------
9271390
9281391class FromPair arity f where
929− parsePair :: Options -> Proxy arity
930− -> (Value -> Parser a) -> (Value -> Parser [a])
931− -> Pair -> Maybe (Parser (f a))
1392+ -- The first component of the parameter tuple is the tag to match.
1393+ parsePair :: Text :* TypeName :* Options :* FromArgs arity a
1394+ -> Value
1395+ -> Maybe (Parser (f a))
9321396
9331397instance ( FromPair arity a
9341398 , FromPair arity b
9351399 ) => FromPair arity (a :+: b) where
936− parsePair opts pa pj pjl pair = (fmap L1 <$> parsePair opts pa pj pjl pair) <|>
937− (fmap R1 <$> parsePair opts pa pj pjl pair)
1400+ parsePair p pair =
1401+ (fmap L1 <$> parsePair p pair) <|>
1402+ (fmap R1 <$> parsePair p pair)
9381403
9391404instance ( Constructor c
940− , GFromJSON arity a
9411405 , ConsFromJSON arity a
9421406 ) => FromPair arity (C1 c a) where
943− parsePair opts pa pj pjl (tag, value)
944− | tag == tag' = Just $ gParseJSON opts pa pj pjl value
1407+ parsePair (tag :* p@(_ :* opts :* _)) v
1408+ | tag == tag' = Just $ M1 <$> consParseJSON (cname :* p) v
9451409 | otherwise = Nothing
946− where
947− tag' = pack $ constructorTagModifier opts $
948− conName (undefined :: t c a p)
1410+ where
1411+ tag' = pack $ constructorTagModifier opts cname
1412+ cname = conName (undefined :: M1 _i c _a _p)
9491413
9501414--------------------------------------------------------------------------------
9511415
952−notFound :: Text -> Parser a
953−notFound key = fail $ "The key \"" ++ unpack key ++ "\" was not found"
954−{-# INLINE notFound #-}
1416+class FromUntaggedValue arity f where
1417+ parseUntaggedValue :: TypeName :* Options :* FromArgs arity a
1418+ -> Value
1419+ -> Parser (f a)
1420+
1421+instance
1422+ ( FromUntaggedValue arity a
1423+ , FromUntaggedValue arity b
1424+ ) => FromUntaggedValue arity (a :+: b)
1425+ where
1426+ parseUntaggedValue p value =
1427+ L1 <$> parseUntaggedValue p value <|>
1428+ R1 <$> parseUntaggedValue p value
1429+
1430+instance OVERLAPPABLE_
1431+ ( ConsFromJSON arity a
1432+ , Constructor c
1433+ ) => FromUntaggedValue arity (C1 c a)
1434+ where
1435+ parseUntaggedValue p = fmap M1 . consParseJSON (cname :* p)
1436+ where
1437+ cname = conName (undefined :: M1 _i c _f _p)
1438+
1439+instance OVERLAPPING_
1440+ ( Constructor c )
1441+ => FromUntaggedValue arity (C1 c U1)
1442+ where
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
9551454
9561455-------------------------------------------------------------------------------
9571456-- Instances
@@ -961,13 +1460,6 @@ notFound key = fail $ "The key \"" ++ unpack key ++ "\" was not found"
9611460-- base
9621461-------------------------------------------------------------------------------
9631462
964−instance FromJSON1 Identity where
965− liftParseJSON p _ a = Identity <$> p a
966− {-# INLINE liftParseJSON #-}
967−
968−instance (FromJSON a) => FromJSON (Identity a) where
969− parseJSON = parseJSON1
970− {-# INLINE parseJSON #-}
9711463
9721464instance FromJSON2 Const where
9731465 liftParseJSON2 p _ _ _ = fmap Const . p
@@ -997,6 +1489,10 @@ instance FromJSON2 Either where
9971489 liftParseJSON2 pA _ pB _ (Object (H.toList -> [(key, value)]))
9981490 | key == left = Left <$> pA value <?> Key left
9991491 | key == right = Right <$> pB value <?> Key right
1492+ where
1493+ left, right :: Text
1494+ left = "Left"
1495+ right = "Right"
10001496
10011497 liftParseJSON2 _ _ _ _ _ = fail $
10021498 "expected an object with a single property " ++
@@ -1012,20 +1508,20 @@ instance (FromJSON a, FromJSON b) => FromJSON (Either a b) where
10121508 parseJSON = parseJSON2
10131509 {-# INLINE parseJSON #-}
10141510
1015−left, right :: Text
1016−left = "Left"
1017−right = "Right"
1018−
1511+instance FromJSON Void where
1512+ parseJSON _ = fail "Cannot parse Void"
1513+ {-# INLINE parseJSON #-}
10191514
10201515instance FromJSON Bool where
1021− parseJSON = withBool "Bool" pure
1516+ parseJSON (Bool b) = pure b
1517+ parseJSON v = typeMismatch "Bool" v
10221518 {-# INLINE parseJSON #-}
10231519
10241520instance FromJSONKey Bool where
10251521 fromJSONKey = FromJSONKeyTextParser $ \t -> case t of
10261522 "true" -> pure True
10271523 "false" -> pure False
1028− _ -> fail $ "Cannot parse key into Bool: " ++ T.unpack t
1524+ _ -> fail $ "cannot parse key " ++ show t ++ " into Bool"
10291525
10301526instance FromJSON Ordering where
10311527 parseJSON = withText "Ordering" $ \s ->
@@ -1033,25 +1529,30 @@ instance FromJSON Ordering where
10331529 "LT" -> return LT
10341530 "EQ" -> return EQ
10351531 "GT" -> return GT
1036− _ -> fail "Parsing Ordering value failed: expected \"LT\", \"EQ\", or \"GT\""
1532+ _ -> fail $ "parsing Ordering failed, unexpected " ++ show s ++
1533+ " (expected \"LT\", \"EQ\", or \"GT\")"
10371534
10381535instance FromJSON () where
10391536 parseJSON = withArray "()" $ \v ->
10401537 if V.null v
10411538 then pure ()
1042− else fail "Expected an empty array"
1539+ else prependContext "()" $ fail "expected an empty array"
10431540 {-# INLINE parseJSON #-}
10441541
10451542instance FromJSON Char where
1046− parseJSON = withText "Char" $ \t ->
1047− if T.compareLength t 1 == EQ
1048− then pure $ T.head t
1049− else fail "Expected a string of length 1"
1543+ parseJSON = withText "Char" parseChar
10501544 {-# INLINE parseJSON #-}
10511545
1052− parseJSONList = withText "String" $ pure . T.unpack
1546+ parseJSONList (String s) = pure (T.unpack s)
1547+ parseJSONList v = typeMismatch "String" v
10531548 {-# INLINE parseJSONList #-}
10541549
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+
10551556instance FromJSON Double where
10561557 parseJSON = parseRealFloat "Double"
10571558 {-# INLINE parseJSON #-}
@@ -1063,12 +1564,6 @@ instance FromJSONKey Double where
10631564 "-Infinity" -> pure (negate 1/0)
10641565 _ -> Scientific.toRealFloat <$> parseScientificText t
10651566
1066−instance FromJSON Number where
1067− parseJSON (Number s) = pure $ scientificToNumber s
1068− parseJSON Null = pure (D (0/0))
1069− parseJSON v = typeMismatch "Number" v
1070− {-# INLINE parseJSON #-}
1071−
10721567instance FromJSON Float where
10731568 parseJSON = parseRealFloat "Float"
10741569 {-# INLINE parseJSON #-}
@@ -1081,111 +1576,133 @@ instance FromJSONKey Float where
10811576 _ -> Scientific.toRealFloat <$> parseScientificText t
10821577
10831578instance (FromJSON a, Integral a) => FromJSON (Ratio a) where
1084− parseJSON = withObject "Rational" $ \obj ->
1085− (%) <$> obj .: "numerator"
1086− <*> obj .: "denominator"
1579+ parseJSON (Number x)
1580+ | exp10 <= 1024
1581+ , exp10 >= -1024 = return $! realToFrac x
1582+ | otherwise = prependContext "Ratio" $ fail msg
1583+ where
1584+ exp10 = base10Exponent x
1585+ msg = "found a number with exponent " ++ show exp10
1586+ ++ ", but it must not be greater than 1024 or less than -1024"
1587+ parseJSON o = objParser o
1588+ where
1589+ objParser = withObject "Rational" $ \obj -> do
1590+ numerator <- obj .: "numerator"
1591+ denominator <- obj .: "denominator"
1592+ if denominator == 0
1593+ then fail "Ratio denominator was 0"
1594+ else pure $ numerator % denominator
10871595 {-# INLINE parseJSON #-}
10881596
1089−-- | /WARNING:/ Only parse fixed-precision numbers from trusted input
1090−-- since an attacker could easily fill up the memory of the target
1091−-- system by specifying a scientific number with a big exponent like
1092−-- @1e1000000000@.
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.
10931601instance HasResolution a => FromJSON (Fixed a) where
1094− parseJSON = withScientific "Fixed" $ pure . realToFrac
1602+ parseJSON = prependContext "Fixed" . withBoundedScientific' (pure . realToFrac)
10951603 {-# INLINE parseJSON #-}
10961604
10971605instance FromJSON Int where
1098− parseJSON = parseIntegral "Int"
1606+ parseJSON = parseBoundedIntegral "Int"
10991607 {-# INLINE parseJSON #-}
11001608
11011609instance FromJSONKey Int where
1102− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1610+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int"
11031611
1104−-- | /WARNING:/ Only parse Integers from trusted input since an
1105−-- attacker could easily fill up the memory of the target system by
1106−-- specifying a scientific number with a big exponent like
1107−-- @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.
11081616instance FromJSON Integer where
1109− parseJSON = withScientific "Integral" $ pure . truncate
1617+ parseJSON = parseIntegral "Integer"
11101618 {-# INLINE parseJSON #-}
11111619
11121620instance FromJSONKey Integer where
1113− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1621+ fromJSONKey = FromJSONKeyTextParser $ parseIntegralText "Integer"
11141622
11151623instance FromJSON Natural where
1116− parseJSON = withScientific "Natural" $ \s ->
1117− if Scientific.coefficient s < 0
1118− then fail $ "Expected a Natural number but got the negative number: " <> show s
1119− else pure $ truncate s
1624+ parseJSON value = do
1625+ integer <- parseIntegral "Natural" value
1626+ parseNatural integer
11201627
11211628instance FromJSONKey Natural where
1122− fromJSONKey = FromJSONKeyTextParser $ \t -> parseScientificText t >>= \s ->
1123− if Scientific.coefficient s < 0
1124− then fail $ "Expected a Natural number but got the negative number: " <> show s
1125− 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
11261639
11271640instance FromJSON Int8 where
1128− parseJSON = parseIntegral "Int8"
1641+ parseJSON = parseBoundedIntegral "Int8"
11291642 {-# INLINE parseJSON #-}
11301643
11311644instance FromJSONKey Int8 where
1132− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1645+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int8"
11331646
11341647instance FromJSON Int16 where
1135− parseJSON = parseIntegral "Int16"
1648+ parseJSON = parseBoundedIntegral "Int16"
11361649 {-# INLINE parseJSON #-}
11371650
11381651instance FromJSONKey Int16 where
1139− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1652+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int16"
11401653
11411654instance FromJSON Int32 where
1142− parseJSON = parseIntegral "Int32"
1655+ parseJSON = parseBoundedIntegral "Int32"
11431656 {-# INLINE parseJSON #-}
11441657
11451658instance FromJSONKey Int32 where
1146− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1659+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int32"
11471660
11481661instance FromJSON Int64 where
1149− parseJSON = parseIntegral "Int64"
1662+ parseJSON = parseBoundedIntegral "Int64"
11501663 {-# INLINE parseJSON #-}
11511664
11521665instance FromJSONKey Int64 where
1153− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1666+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int64"
11541667
11551668instance FromJSON Word where
1156− parseJSON = parseIntegral "Word"
1669+ parseJSON = parseBoundedIntegral "Word"
11571670 {-# INLINE parseJSON #-}
11581671
11591672instance FromJSONKey Word where
1160− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1673+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word"
11611674
11621675instance FromJSON Word8 where
1163− parseJSON = parseIntegral "Word8"
1676+ parseJSON = parseBoundedIntegral "Word8"
11641677 {-# INLINE parseJSON #-}
11651678
11661679instance FromJSONKey Word8 where
1167− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1680+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word8"
11681681
11691682instance FromJSON Word16 where
1170− parseJSON = parseIntegral "Word16"
1683+ parseJSON = parseBoundedIntegral "Word16"
11711684 {-# INLINE parseJSON #-}
11721685
11731686instance FromJSONKey Word16 where
1174− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1687+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word16"
11751688
11761689instance FromJSON Word32 where
1177− parseJSON = parseIntegral "Word32"
1690+ parseJSON = parseBoundedIntegral "Word32"
11781691 {-# INLINE parseJSON #-}
11791692
11801693instance FromJSONKey Word32 where
1181− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1694+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word32"
11821695
11831696instance FromJSON Word64 where
1184− parseJSON = parseIntegral "Word64"
1697+ parseJSON = parseBoundedIntegral "Word64"
11851698 {-# INLINE parseJSON #-}
11861699
11871700instance FromJSONKey Word64 where
1188− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1701+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word64"
1702+
1703+instance FromJSON CTime where
1704+ parseJSON = fmap CTime . parseJSON
1705+ {-# INLINE parseJSON #-}
11891706
11901707instance FromJSON Text where
11911708 parseJSON = withText "Text" pure
@@ -1194,27 +1711,38 @@ instance FromJSON Text where
11941711instance FromJSONKey Text where
11951712 fromJSONKey = fromJSONKeyCoerce
11961713
1714+
11971715instance FromJSON LT.Text where
11981716 parseJSON = withText "Lazy Text" $ pure . LT.fromStrict
11991717 {-# INLINE parseJSON #-}
12001718
1719+instance FromJSONKey LT.Text where
1720+ fromJSONKey = FromJSONKeyText LT.fromStrict
1721+
1722+
12011723instance FromJSON Version where
1724+ parseJSON = withText "Version" parseVersionText
12021725 {-# INLINE parseJSON #-}
1203− parseJSON = withText "Version" $ go . readP_to_S parseVersion . unpack
1204− where
1205− go [(v,[])] = return v
1206− go (_ : xs) = go xs
1207− go _ = fail $ "could not parse Version"
1726+
1727+instance FromJSONKey Version where
1728+ fromJSONKey = FromJSONKeyTextParser parseVersionText
1729+
1730+parseVersionText :: Text -> Parser Version
1731+parseVersionText = go . readP_to_S parseVersion . unpack
1732+ where
1733+ go [(v,[])] = return v
1734+ go (_ : xs) = go xs
1735+ go _ = fail "parsing Version failed"
12081736
12091737-------------------------------------------------------------------------------
12101738-- semigroups NonEmpty
12111739-------------------------------------------------------------------------------
12121740
12131741instance FromJSON1 NonEmpty where
1214− liftParseJSON p _ = withArray "NonEmpty a" $
1742+ liftParseJSON p _ = withArray "NonEmpty" $
12151743 (>>= ne) . Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
12161744 where
1217− ne [] = fail "Expected a NonEmpty but got an empty list"
1745+ ne [] = fail "parsing NonEmpty failed, unexpected empty list"
12181746 ne (x:xs) = pure (x :| xs)
12191747 {-# INLINE liftParseJSON #-}
12201748
@@ -1235,7 +1763,7 @@ instance FromJSON Scientific where
12351763-------------------------------------------------------------------------------
12361764
12371765instance FromJSON1 DList.DList where
1238− liftParseJSON p _ = withArray "DList a" $
1766+ liftParseJSON p _ = withArray "DList" $
12391767 fmap DList.fromList .
12401768 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
12411769 {-# INLINE liftParseJSON #-}
@@ -1244,12 +1772,89 @@ instance (FromJSON a) => FromJSON (DList.DList a) where
12441772 parseJSON = parseJSON1
12451773 {-# INLINE parseJSON #-}
12461774
1775+-------------------------------------------------------------------------------
1776+-- tranformers - Functors
1777+-------------------------------------------------------------------------------
1778+
1779+instance FromJSON1 Identity where
1780+ liftParseJSON p _ a = Identity <$> p a
1781+ {-# INLINE liftParseJSON #-}
1782+
1783+ liftParseJSONList _ p a = fmap Identity <$> p a
1784+ {-# INLINE liftParseJSONList #-}
1785+
1786+instance (FromJSON a) => FromJSON (Identity a) where
1787+ parseJSON = parseJSON1
1788+ {-# INLINE parseJSON #-}
1789+
1790+ parseJSONList = liftParseJSONList parseJSON parseJSONList
1791+ {-# INLINE parseJSONList #-}
1792+
1793+instance (FromJSONKey a) => FromJSONKey (Identity a) where
1794+ fromJSONKey = coerceFromJSONKeyFunction (fromJSONKey :: FromJSONKeyFunction a)
1795+ fromJSONKeyList = coerceFromJSONKeyFunction (fromJSONKeyList :: FromJSONKeyFunction [a])
1796+
1797+
1798+instance (FromJSON1 f, FromJSON1 g) => FromJSON1 (Compose f g) where
1799+ liftParseJSON p pl a = Compose <$> liftParseJSON g gl a
1800+ where
1801+ g = liftParseJSON p pl
1802+ gl = liftParseJSONList p pl
1803+ {-# INLINE liftParseJSON #-}
1804+
1805+ liftParseJSONList p pl a = map Compose <$> liftParseJSONList g gl a
1806+ where
1807+ g = liftParseJSON p pl
1808+ gl = liftParseJSONList p pl
1809+ {-# INLINE liftParseJSONList #-}
1810+
1811+instance (FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Compose f g a) where
1812+ parseJSON = parseJSON1
1813+ {-# INLINE parseJSON #-}
1814+
1815+ parseJSONList = liftParseJSONList parseJSON parseJSONList
1816+ {-# INLINE parseJSONList #-}
1817+
1818+
1819+instance (FromJSON1 f, FromJSON1 g) => FromJSON1 (Product f g) where
1820+ liftParseJSON p pl a = uncurry Pair <$> liftParseJSON2 px pxl py pyl a
1821+ where
1822+ px = liftParseJSON p pl
1823+ pxl = liftParseJSONList p pl
1824+ py = liftParseJSON p pl
1825+ pyl = liftParseJSONList p pl
1826+ {-# INLINE liftParseJSON #-}
1827+
1828+instance (FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Product f g a) where
1829+ parseJSON = parseJSON1
1830+ {-# INLINE parseJSON #-}
1831+
1832+
1833+instance (FromJSON1 f, FromJSON1 g) => FromJSON1 (Sum f g) where
1834+ liftParseJSON p pl (Object (H.toList -> [(key, value)]))
1835+ | key == inl = InL <$> liftParseJSON p pl value <?> Key inl
1836+ | key == inr = InR <$> liftParseJSON p pl value <?> Key inl
1837+ where
1838+ inl, inr :: Text
1839+ inl = "InL"
1840+ inr = "InR"
1841+
1842+ liftParseJSON _ _ _ = fail $
1843+ "parsing Sum failed, expected an object with a single property " ++
1844+ "where the property key should be either " ++
1845+ "\"InL\" or \"InR\""
1846+ {-# INLINE liftParseJSON #-}
1847+
1848+instance (FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum f g a) where
1849+ parseJSON = parseJSON1
1850+ {-# INLINE parseJSON #-}
1851+
12471852-------------------------------------------------------------------------------
12481853-- containers
12491854-------------------------------------------------------------------------------
12501855
12511856instance FromJSON1 Seq.Seq where
1252− liftParseJSON p _ = withArray "Seq a" $
1857+ liftParseJSON p _ = withArray "Seq" $
12531858 fmap Seq.fromList .
12541859 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
12551860 {-# INLINE liftParseJSON #-}
@@ -1283,15 +1888,15 @@ instance FromJSON a => FromJSON (IntMap.IntMap a) where
12831888
12841889instance (FromJSONKey k, Ord k) => FromJSON1 (M.Map k) where
12851890 liftParseJSON p _ = case fromJSONKey of
1286− FromJSONKeyCoerce _-> withObject "Map k v" $
1891+ FromJSONKeyCoerce _ -> withObject "Map" $
12871892 fmap (H.foldrWithKey (M.insert . unsafeCoerce) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1288− FromJSONKeyText f -> withObject "Map k v" $
1893+ FromJSONKeyText f -> withObject "Map" $
12891894 fmap (H.foldrWithKey (M.insert . f) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1290− FromJSONKeyTextParser f -> withObject "Map k v" $
1291− H.foldrWithKey (\k v m -> M.insert <$> f k <*> (p v <?> Key k) <*> m) (pure M.empty)
1292− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1293− M.fromList <$> (Tr.sequence .
1294− zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr)
1895+ FromJSONKeyTextParser f -> withObject "Map" $
1896+ H.foldrWithKey (\k v m -> M.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure M.empty)
1897+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
1898+ fmap M.fromList . Tr.sequence .
1899+ zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
12951900 {-# INLINE liftParseJSON #-}
12961901
12971902instance (FromJSONKey k, Ord k, FromJSON v) => FromJSON (M.Map k v) where
@@ -1311,12 +1916,24 @@ instance (FromJSON v) => FromJSON (Tree.Tree v) where
13111916 parseJSON = parseJSON1
13121917 {-# INLINE parseJSON #-}
13131918
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+
13141931-------------------------------------------------------------------------------
13151932-- vector
13161933-------------------------------------------------------------------------------
13171934
13181935instance FromJSON1 Vector where
1319− liftParseJSON p _ = withArray "Vector a" $
1936+ liftParseJSON p _ = withArray "Vector" $
13201937 V.mapM (uncurry $ parseIndexedJSON p) . V.indexed
13211938 {-# INLINE liftParseJSON #-}
13221939
@@ -1330,14 +1947,14 @@ vectorParseJSON s = withArray s $ fmap V.convert . V.mapM (uncurry $ parseIndexe
13301947{-# INLINE vectorParseJSON #-}
13311948
13321949instance (Storable a, FromJSON a) => FromJSON (VS.Vector a) where
1333− parseJSON = vectorParseJSON "Data.Vector.Storable.Vector a"
1950+ parseJSON = vectorParseJSON "Data.Vector.Storable.Vector"
13341951
13351952instance (VP.Prim a, FromJSON a) => FromJSON (VP.Vector a) where
1336− parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector a"
1953+ parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector"
13371954 {-# INLINE parseJSON #-}
13381955
13391956instance (VG.Vector VU.Vector a, FromJSON a) => FromJSON (VU.Vector a) where
1340− parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector a"
1957+ parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector"
13411958 {-# INLINE parseJSON #-}
13421959
13431960-------------------------------------------------------------------------------
@@ -1351,15 +1968,15 @@ instance (Eq a, Hashable a, FromJSON a) => FromJSON (HashSet.HashSet a) where
13511968
13521969instance (FromJSONKey k, Eq k, Hashable k) => FromJSON1 (H.HashMap k) where
13531970 liftParseJSON p _ = case fromJSONKey of
1354− FromJSONKeyCoerce _ -> withObject "HashMap ~Text v" $
1971+ FromJSONKeyCoerce _ -> withObject "HashMap ~Text" $
13551972 uc . H.traverseWithKey (\k v -> p v <?> Key k)
1356− FromJSONKeyText f -> withObject "HashMap k v" $
1973+ FromJSONKeyText f -> withObject "HashMap" $
13571974 fmap (mapKey f) . H.traverseWithKey (\k v -> p v <?> Key k)
1358− FromJSONKeyTextParser f -> withObject "HashMap k v" $
1359− H.foldrWithKey (\k v m -> H.insert <$> f k <*> (p v <?> Key k) <*> m) (pure H.empty)
1360− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1361− H.fromList <$> (Tr.sequence .
1362− zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr)
1975+ FromJSONKeyTextParser f -> withObject "HashMap" $
1976+ H.foldrWithKey (\k v m -> H.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure H.empty)
1977+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
1978+ fmap H.fromList . Tr.sequence .
1979+ zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
13631980 where
13641981 uc :: Parser (H.HashMap Text v) -> Parser (H.HashMap k v)
13651982 uc = unsafeCoerce
@@ -1380,11 +1997,33 @@ instance FromJSON DotNetTime where
13801997 parseJSON = withText "DotNetTime" $ \t ->
13811998 let (s,m) = T.splitAt (T.length t - 5) t
13821999 t' = T.concat [s,".",m]
1383− in case parseTime defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
2000+ in case parseTimeM True defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
13842001 Just d -> pure (DotNetTime d)
13852002 _ -> fail "could not parse .NET time"
13862003 {-# INLINE parseJSON #-}
13872004
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+
13882027-------------------------------------------------------------------------------
13892028-- time
13902029-------------------------------------------------------------------------------
@@ -1410,6 +2049,17 @@ instance FromJSONKey LocalTime where
14102049 fromJSONKey = FromJSONKeyTextParser (Time.run Time.localTime)
14112050
14122051
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.
14132063instance FromJSON ZonedTime where
14142064 parseJSON = withText "ZonedTime" (Time.run Time.zonedTime)
14152065
@@ -1424,41 +2074,168 @@ instance FromJSONKey UTCTime where
14242074 fromJSONKey = FromJSONKeyTextParser (Time.run Time.utcTime)
14252075
14262076
1427−-- | /WARNING:/ Only parse lengths of time from trusted input
1428−-- since an attacker could easily fill up the memory of the target
1429−-- system by specifying a scientific number with a big exponent like
1430−-- @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.
14312081instance FromJSON NominalDiffTime where
1432− parseJSON = withScientific "NominalDiffTime" $ pure . realToFrac
2082+ parseJSON = withBoundedScientific "NominalDiffTime" $ pure . realToFrac
2083+ {-# INLINE parseJSON #-}
2084+
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
14332092 {-# INLINE parseJSON #-}
14342093
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+
14352128-------------------------------------------------------------------------------
14362129-- base Monoid/Semigroup
14372130-------------------------------------------------------------------------------
14382131
1439−instance FromJSON1 Dual where
1440− 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'
14412143 {-# INLINE liftParseJSON #-}
14422144
1443−instance FromJSON a => FromJSON (Dual a) where
2145+instance FromJSON a => FromJSON (Monoid.First a) where
14442146 parseJSON = parseJSON1
14452147 {-# INLINE parseJSON #-}
14462148
14472149
1448−instance FromJSON1 First where
1449− liftParseJSON p p' = fmap First . liftParseJSON p p'
2150+instance FromJSON1 Monoid.Last where
2151+ liftParseJSON p p' = fmap Monoid.Last . liftParseJSON p p'
14502152 {-# INLINE liftParseJSON #-}
14512153
1452−instance FromJSON a => FromJSON (First a) where
2154+instance FromJSON a => FromJSON (Monoid.Last a) where
14532155 parseJSON = parseJSON1
14542156 {-# INLINE parseJSON #-}
14552157
14562158
1457−instance FromJSON1 Last where
1458− liftParseJSON p p' = fmap Last . liftParseJSON p p'
2159+instance FromJSON1 Semigroup.Min where
2160+ liftParseJSON p _ a = Semigroup.Min <$> p a
14592161 {-# INLINE liftParseJSON #-}
14602162
1461−instance FromJSON a => FromJSON (Last a) where
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
2191+ {-# INLINE liftParseJSON #-}
2192+
2193+ liftParseJSONList _ p a = fmap Semigroup.First <$> p a
2194+ {-# INLINE liftParseJSONList #-}
2195+
2196+instance (FromJSON a) => FromJSON (Semigroup.First a) where
2197+ parseJSON = parseJSON1
2198+ {-# INLINE parseJSON #-}
2199+
2200+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2201+ {-# INLINE parseJSONList #-}
2202+
2203+
2204+instance FromJSON1 Semigroup.Last where
2205+ liftParseJSON p _ a = Semigroup.Last <$> p a
2206+ {-# INLINE liftParseJSON #-}
2207+
2208+ liftParseJSONList _ p a = fmap Semigroup.Last <$> p a
2209+ {-# INLINE liftParseJSONList #-}
2210+
2211+instance (FromJSON a) => FromJSON (Semigroup.Last a) where
2212+ parseJSON = parseJSON1
2213+ {-# INLINE parseJSON #-}
2214+
2215+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2216+ {-# INLINE parseJSONList #-}
2217+
2218+
2219+instance FromJSON1 Semigroup.WrappedMonoid where
2220+ liftParseJSON p _ a = Semigroup.WrapMonoid <$> 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'
2236+ {-# INLINE liftParseJSON #-}
2237+
2238+instance FromJSON a => FromJSON (Semigroup.Option a) where
14622239 parseJSON = parseJSON1
14632240 {-# INLINE parseJSON #-}
14642241
@@ -1466,11 +2243,21 @@ instance FromJSON a => FromJSON (Last a) where
14662243-- tagged
14672244-------------------------------------------------------------------------------
14682245
2246+instance FromJSON1 Proxy where
2247+ {-# INLINE liftParseJSON #-}
2248+ liftParseJSON _ _ = fromNull "Proxy" Proxy
2249+
14692250instance FromJSON (Proxy a) where
14702251 {-# INLINE parseJSON #-}
1471− parseJSON Null = pure Proxy
1472− parseJSON v = typeMismatch "Proxy" v
2252+ parseJSON = fromNull "Proxy" Proxy
2253+
2254+fromNull :: String -> a -> Value -> Parser a
2255+fromNull _ a Null = pure a
2256+fromNull c _ v = prependContext c (typeMismatch "Null" v)
14732257
2258+instance FromJSON2 Tagged where
2259+ liftParseJSON2 _ _ p _ = fmap Tagged . p
2260+ {-# INLINE liftParseJSON2 #-}
14742261
14752262instance FromJSON1 (Tagged a) where
14762263 liftParseJSON p _ = fmap Tagged . p
@@ -1493,23 +2280,17 @@ instance (FromJSON a, FromJSON b, FromJSON c) => FromJSONKey (a,b,c)
14932280instance (FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSONKey (a,b,c,d)
14942281
14952282instance FromJSONKey Char where
1496− fromJSONKey = FromJSONKeyTextParser $ \t ->
1497− if T.length t == 1
1498− then return (T.index t 0)
1499− else typeMismatch "Expected Char but String didn't contain exactly one character" (String t)
2283+ fromJSONKey = FromJSONKeyTextParser parseChar
15002284 fromJSONKeyList = FromJSONKeyText T.unpack
15012285
15022286instance (FromJSONKey a, FromJSON a) => FromJSONKey [a] where
15032287 fromJSONKey = fromJSONKeyList
15042288
1505−instance (FromJSONKey a, FromJSON a) => FromJSONKey (Identity a) where
1506− fromJSONKey = mapFromJSONKeyFunction Identity fromJSONKey
1507−
15082289-------------------------------------------------------------------------------
15092290-- Tuple instances, see tuple-instances-from.hs
15102291-------------------------------------------------------------------------------
15112292
1512−instance FromJSON2 ((,) ) where
2293+instance FromJSON2 (,) where
15132294 liftParseJSON2 pA _ pB _ = withArray "(a, b)" $ \t ->
15142295 let n = V.length t
15152296 in if n == 2