@@ -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
@@ -42,106 +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.Compose (Compose (..))
86−import Data.Functor.Identity (Identity (..))
87−import Data.Functor.Product (Product (..))
88−import Data.Functor.Sum (Sum (..))
89−import Data.Hashable (Hashable (..))
90−import Data.Int (Int16, Int32, Int64, Int8)
91−import Data.List.NonEmpty (NonEmpty (..))
92−import Data.Maybe (fromMaybe)
93−import Data.Monoid (Dual (..), First (..), Last (..), (<>))
94−import Data.Proxy (Proxy (..))
95−import Data.Ratio (Ratio, (%))
96−import Data.Scientific (Scientific)
97−import Data.Tagged (Tagged (..))
98−import Data.Text (Text, pack, unpack)
99−import Data.Time (Day, LocalTime, NominalDiffTime, TimeOfDay,
100− UTCTime, ZonedTime)
101−import Data.Time.Format (parseTime)
102−import Data.Time.Locale.Compat (defaultTimeLocale)
103−import Data.Traversable as Tr (sequence)
104−import Data.Vector (Vector)
105−import Data.Version (Version, parseVersion)
106−import Data.Word (Word16, Word32, Word64, Word8)
107−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 (..))
108117import GHC.Generics
109−import Numeric.Natural (Natural)
118+import Numeric.Natural (Natural)
110119import Text.ParserCombinators.ReadP (readP_to_S)
111−
112−import qualified Data.DList as DList
113−import qualified Data.HashMap.Strict as H
114−import qualified Data.HashSet as HashSet
115−import qualified Data.IntMap as IntMap
116−import qualified Data.IntSet as IntSet
117−import qualified Data.Map as M
118−import qualified Data.Scientific as Scientific
119−import qualified Data.Sequence as Seq
120−import qualified Data.Set as Set
121−import qualified Data.Text as T
122−import qualified Data.Text.Encoding as T
123−import qualified Data.Text.Lazy as LT
124−import qualified Data.Tree as Tree
125−import qualified Data.Vector as V
126−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
127142import qualified Data.Vector.Primitive as VP
128−import qualified Data.Vector.Storable as VS
129−import qualified Data.Vector.Unboxed as VU
143+import qualified Data.Vector.Storable as VS
144+import qualified Data.Vector.Unboxed as VU
130145
131−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
132150
133−#ifndef HAS_COERCIBLE
134−#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
135154#endif
155+import qualified Data.Primitive.PrimArray as PM
156+#endif
157+
136158
137−#if HAS_COERCIBLE
138159import Data.Coerce (Coercible, coerce)
139−coerce' :: Coercible a b => a -> b
140−coerce' = coerce
141−#else
142−coerce' :: a -> b
143−coerce' = unsafeCoerce
144−#endif
145160
146161parseIndexedJSON :: (Value -> Parser a) -> Int -> Value -> Parser a
147162parseIndexedJSON p idx value = p value <?> Index idx
@@ -150,7 +165,7 @@ parseIndexedJSON p idx value = p value <?> Index idx
150165parseIndexedJSONPair :: (Value -> Parser a) -> (Value -> Parser b) -> Int -> Value -> Parser (a, b)
151166parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
152167 where
153− p = withArray "(k,v)" $ \ab ->
168+ p = withArray "(k, v)" $ \ab ->
154169 let n = V.length ab
155170 in if n == 2
156171 then (,) <$> parseJSONElemAtIndex keyParser 0 ab
@@ -162,33 +177,57 @@ parseIndexedJSONPair keyParser valParser idx value = p value <?> Index idx
162177parseJSONElemAtIndex :: (Value -> Parser a) -> Int -> V.Vector Value -> Parser a
163178parseJSONElemAtIndex p idx ary = p (V.unsafeIndex ary idx) <?> Index idx
164179
165−scientificToNumber :: Scientific -> Number
166−scientificToNumber s
167− | e < 0 = D $ Scientific.toRealFloat s
168− | otherwise = I $ c * 10 ^ e
169− where
170− e = Scientific.base10Exponent s
171− c = Scientific.coefficient s
172−{-# INLINE scientificToNumber #-}
173−
174180parseRealFloat :: RealFloat a => String -> Value -> Parser a
175−parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
176−parseRealFloat _ Null = pure (0/0)
177−parseRealFloat expected v = typeMismatch expected v
181+parseRealFloat _ (Number s) = pure $ Scientific.toRealFloat s
182+parseRealFloat _ Null = pure (0/0)
183+parseRealFloat name v = prependContext name (unexpected v)
178184{-# INLINE parseRealFloat #-}
179185
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+
180193parseIntegral :: Integral a => String -> Value -> Parser a
181−parseIntegral expected = withScientific expected $ pure . truncate
194+parseIntegral name =
195+ prependContext name . withBoundedScientific' parseIntegralFromScientific
182196{-# INLINE parseIntegral #-}
183197
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+
184210parseScientificText :: Text -> Parser Scientific
185211parseScientificText
186212 = either fail pure
187213 . A.parseOnly (A.scientific <* A.endOfInput)
188214 . T.encodeUtf8
189215
190−parseIntegralText :: Integral a => Text -> Parser a
191−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
192231
193232parseOptionalFieldWith :: (Value -> Parser (Maybe a))
194233 -> Object -> Text -> Parser (Maybe a)
@@ -207,16 +246,21 @@ class GFromJSON arity f where
207246 -- | This method (applied to 'defaultOptions') is used as the
208247 -- default generic implementation of 'parseJSON' (if the @arity@ is 'Zero')
209248 -- or 'liftParseJSON' (if the @arity@ is 'One').
210− gParseJSON :: Options -> Proxy arity
211− -> (Value -> Parser a) -> (Value -> Parser [a])
212− -> 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
213257
214258-- | A configurable generic JSON decoder. This function applied to
215259-- 'defaultOptions' is used as the default for 'parseJSON' when the
216260-- type is an instance of 'Generic'.
217261genericParseJSON :: (Generic a, GFromJSON Zero (Rep a))
218262 => Options -> Value -> Parser a
219−genericParseJSON opts = fmap to . gParseJSON opts proxyZero undefined undefined
263+genericParseJSON opts = fmap to . gParseJSON opts NoFromArgs
220264
221265-- | A configurable generic JSON decoder. This function applied to
222266-- 'defaultOptions' is used as the default for 'liftParseJSON' when the
@@ -224,7 +268,7 @@ genericParseJSON opts = fmap to . gParseJSON opts proxyZero undefined undefined
224268genericLiftParseJSON :: (Generic1 f, GFromJSON One (Rep1 f))
225269 => Options -> (Value -> Parser a) -> (Value -> Parser [a])
226270 -> Value -> Parser (f a)
227−genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
271+genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts (From1Args pj pjl)
228272
229273-------------------------------------------------------------------------------
230274-- Class
@@ -243,14 +287,21 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
243287--
244288-- The basic ways to signal a failed conversion are as follows:
245289--
246−-- * '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;
247292--
248−-- * '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 @('<|>')@;
249295--
250−-- * 'typeMismatch' produces an informative message for cases when the
251−-- 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.
252300--
253−-- 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':
254305--
255306-- @
256307-- \-- Allow ourselves to write 'Text' literals.
@@ -258,15 +309,30 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
258309--
259310-- data Coord = Coord { x :: Double, y :: Double }
260311--
261−-- instance FromJSON Coord where
262−-- parseJSON ('Object' v) = Coord '<$>'
263−-- v '.:' \"x\" '<*>'
264−-- v '.:' \"y\"
312+-- instance 'FromJSON' Coord where
313+-- 'parseJSON' ('Object' v) = Coord
314+-- '<$>' v '.:' \"x\"
315+-- '<*>' v '.:' \"y\"
265316--
266−-- \-- We do not expect a non-'Object' value here.
267−-- \-- We could use 'mzero' to fail, but 'typeMismatch'
268−-- \-- gives a much more informative error message.
269−-- parseJSON invalid = 'typeMismatch' \"Coord\" invalid
317+-- \-- We do not expect a non-'Object' value here.
318+-- \-- We could use 'Control.Applicative.empty' to fail, but 'typeMismatch'
319+-- \-- gives a much more informative error message.
320+-- 'parseJSON' invalid =
321+-- 'prependFailure' "parsing Coord failed, "
322+-- ('typeMismatch' \"Object\" invalid)
323+-- @
324+--
325+-- For this common case of only being concerned with a single
326+-- type of JSON value, the functions 'withObject', 'withScientific', etc.
327+-- are provided. Their use is to be preferred when possible, since
328+-- they are more terse. Using 'withObject', we can rewrite the above instance
329+-- (assuming the same language extension and data type) as:
330+--
331+-- @
332+-- instance 'FromJSON' Coord where
333+-- 'parseJSON' = 'withObject' \"Coord\" $ \\v -> Coord
334+-- '<$>' v '.:' \"x\"
335+-- '<*>' v '.:' \"y\"
270336-- @
271337--
272338-- Instead of manually writing your 'FromJSON' instance, there are two options
@@ -274,7 +340,7 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
274340--
275341-- * "Data.Aeson.TH" provides Template Haskell functions which will derive an
276342-- instance at compile time. The generated instance is optimized for your type
277−-- so will probably be more efficient than the following two options:
343+-- so it will probably be more efficient than the following option.
278344--
279345-- * The compiler can provide a default generic implementation for
280346-- 'parseJSON'.
@@ -292,18 +358,21 @@ genericLiftParseJSON opts pj pjl = fmap to1 . gParseJSON opts proxyOne pj pjl
292358--
293359-- data Coord = Coord { x :: Double, y :: Double } deriving 'Generic'
294360--
295−-- instance FromJSON Coord
361+-- instance 'FromJSON' Coord
296362-- @
297363--
298−-- If @DefaultSignatures@ doesn't give exactly the results you want,
299−-- you can customize the generic decoding with only a tiny amount of
300−-- 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:
301367--
302368-- @
303−-- instance FromJSON Coord where
304−-- parseJSON = 'genericParseJSON' 'defaultOptions'
369+-- customOptions = 'defaultOptions'
370+-- { 'fieldLabelModifier' = 'map' 'Data.Char.toUpper'
371+-- }
372+--
373+-- instance 'FromJSON' Coord where
374+-- 'parseJSON' = 'genericParseJSON' customOptions
305375-- @
306−
307376class FromJSON a where
308377 parseJSON :: Value -> Parser a
309378
@@ -311,61 +380,89 @@ class FromJSON a where
311380 parseJSON = genericParseJSON defaultOptions
312381
313382 parseJSONList :: Value -> Parser [a]
314− parseJSONList (Array a)
315− = sequence
316− . zipWith (parseIndexedJSON parseJSON) [0..]
383+ parseJSONList = withArray "[]" $ \a ->
384+ zipWithM (parseIndexedJSON parseJSON) [0..]
317385 . V.toList
318386 $ a
319387
320− parseJSONList v = typeMismatch "[a]" v
321−
322388-------------------------------------------------------------------------------
323389-- Classes and types for map keys
324390-------------------------------------------------------------------------------
325391
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+-- @
326409class FromJSONKey a where
410+ -- | Strategy for parsing the key of a map-like container.
327411 fromJSONKey :: FromJSONKeyFunction a
328412 default fromJSONKey :: FromJSON a => FromJSONKeyFunction a
329413 fromJSONKey = FromJSONKeyValue parseJSON
330414
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.
331419 fromJSONKeyList :: FromJSONKeyFunction [a]
332420 default fromJSONKeyList :: FromJSON a => FromJSONKeyFunction [a]
333421 fromJSONKeyList = FromJSONKeyValue parseJSON
334422
335−-- | With GHC 7.8 + we carry around 'Coercible Text a' dictionary,
336−-- to have even some amount of safety net.
337−-- 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.
338427--
339−-- ATM this type is intentionally not exported. FromJSONKeyFunction can be inspected,
340−-- but cannot be constructed.
428+-- At the moment this type is intentionally not exported. 'FromJSONKeyFunction'
429+-- can be inspected, but cannot be constructed.
341430data CoerceText a where
342−#if HAS_COERCIBLE
343431 CoerceText :: Coercible Text a => CoerceText a
344−#else
345− CoerceText :: CoerceText a
346−#endif
347432
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.
348439data FromJSONKeyFunction a
349440 = FromJSONKeyCoerce !(CoerceText a)
441+ -- ^ uses 'coerce' ('unsafeCoerce' in older GHCs)
350442 | FromJSONKeyText !(Text -> a)
443+ -- ^ conversion from 'Text' that always succeeds
351444 | FromJSONKeyTextParser !(Text -> Parser a)
445+ -- ^ conversion from 'Text' that may fail
352446 | FromJSONKeyValue !(Value -> Parser a)
447+ -- ^ conversion for non-textual keys
353448
449+-- | Only law abiding up to interpretation
354450instance Functor FromJSONKeyFunction where
355− fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce')
451+ fmap h (FromJSONKeyCoerce CoerceText) = FromJSONKeyText (h . coerce)
356452 fmap h (FromJSONKeyText f) = FromJSONKeyText (h . f)
357453 fmap h (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap h . f)
358454 fmap h (FromJSONKeyValue f) = FromJSONKeyValue (fmap h . f)
359455
360456-- | Construct 'FromJSONKeyFunction' for types coercible from 'Text'. This
361457-- 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.
362461-- compatible with 'Text' i.e. hash values be equal for wrapped values as well.
363462--
364463-- On pre GHC 7.8 this is unconstrainted function.
365464fromJSONKeyCoerce ::
366−#if HAS_COERCIBLE
367465 Coercible Text a =>
368−#endif
369466 FromJSONKeyFunction a
370467fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
371468
@@ -373,60 +470,91 @@ fromJSONKeyCoerce = FromJSONKeyCoerce CoerceText
373470--
374471-- See note on 'fromJSONKeyCoerce'.
375472coerceFromJSONKeyFunction ::
376−#if HAS_COERCIBLE
377473 Coercible a b =>
378−#endif
379474 FromJSONKeyFunction a -> FromJSONKeyFunction b
380−#if HAS_COERCIBLE
381475coerceFromJSONKeyFunction = coerce
382−#else
383−coerceFromJSONKeyFunction (FromJSONKeyCoerce CoerceText) = FromJSONKeyCoerce CoerceText
384−coerceFromJSONKeyFunction (FromJSONKeyText f) = FromJSONKeyText (coerce' . f)
385−coerceFromJSONKeyFunction (FromJSONKeyTextParser f) = FromJSONKeyTextParser (fmap coerce' . f)
386−coerceFromJSONKeyFunction (FromJSONKeyValue f) = FromJSONKeyValue (fmap coerce' . f)
387−#endif
388476
389477{-# RULES
390478 "FromJSONKeyCoerce: fmap id" forall (x :: FromJSONKeyFunction a).
391479 fmap id x = x
392480 #-}
393−#if HAS_COERCIBLE
394481{-# RULES
395482 "FromJSONKeyCoerce: fmap coerce" forall x .
396483 fmap coerce x = coerceFromJSONKeyFunction x
397484 #-}
398−#endif
399485
400486-- | Same as 'fmap'. Provided for the consistency with 'ToJSONKeyFunction'.
401487mapFromJSONKeyFunction :: (a -> b) -> FromJSONKeyFunction a -> FromJSONKeyFunction b
402488mapFromJSONKeyFunction = fmap
403489
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+
404519-------------------------------------------------------------------------------
405520-- Functions needed for documentation
406521-------------------------------------------------------------------------------
407522
408523-- | Fail parsing due to a type mismatch, with a descriptive message.
409524--
410−-- Example usage:
525+-- The following wrappers should generally be prefered:
526+-- 'withObject', 'withArray', 'withText', 'withBool'.
411527--
412−-- @
413−-- instance FromJSON Coord where
414−-- parseJSON ('Object' v) = {- type matches, life is good -}
415−-- parseJSON wat = 'typeMismatch' \"Coord\" wat
416−-- @
417−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\"@).
418535 -> Value -- ^ The actual value encountered.
419536 -> Parser a
420537typeMismatch expected actual =
421− fail $ "expected " ++ expected ++ ", encountered " ++ name
422− where
423− name = case actual of
424− Object _ -> "Object"
425− Array _ -> "Array"
426− String _ -> "String"
427− Number _ -> "Number"
428− Bool _ -> "Boolean"
429− 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"
430558
431559-------------------------------------------------------------------------------
432560-- Lifings of FromJSON and ToJSON to unary and binary type constructors
@@ -439,7 +567,7 @@ typeMismatch expected actual =
439567--
440568-- * "Data.Aeson.TH" provides Template Haskell functions which will derive an
441569-- instance at compile time. The generated instance is optimized for your type
442−-- so will probably be more efficient than the following two options:
570+-- so it will probably be more efficient than the following option.
443571--
444572-- * The compiler can provide a default generic implementation for
445573-- 'liftParseJSON'.
@@ -457,16 +585,20 @@ typeMismatch expected actual =
457585--
458586-- data Pair a b = Pair { pairFst :: a, pairSnd :: b } deriving 'Generic1'
459587--
460−-- instance FromJSON a => FromJSON1 (Pair a)
588+-- instance 'FromJSON' a => 'FromJSON1' (Pair a)
461589-- @
462590--
463−-- If @DefaultSignatures@ doesn't give exactly the results you want,
591+-- If the default implementation doesn't give exactly the results you want,
464592-- you can customize the generic decoding with only a tiny amount of
465593-- effort, using 'genericLiftParseJSON' with your preferred 'Options':
466594--
467595-- @
468−-- instance FromJSON a => FromJSON1 (Pair a) where
469−-- 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
470602-- @
471603class FromJSON1 f where
472604 liftParseJSON :: (Value -> Parser a) -> (Value -> Parser [a]) -> Value -> Parser (f a)
@@ -503,9 +635,8 @@ class FromJSON2 f where
503635 -> (Value -> Parser b)
504636 -> (Value -> Parser [b])
505637 -> Value -> Parser [f a b]
506− liftParseJSONList2 fa ga fb gb v = case v of
507− Array vals -> fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
508− _ -> typeMismatch "[a]" v
638+ liftParseJSONList2 fa ga fb gb = withArray "[]" $ \vals ->
639+ fmap V.toList (V.mapM (liftParseJSON2 fa ga fb gb) vals)
509640
510641-- | Lift the standard 'parseJSON' function through the type constructor.
511642parseJSON2 :: (FromJSON2 f, FromJSON a, FromJSON b) => Value -> Parser (f a b)
@@ -516,9 +647,10 @@ parseJSON2 = liftParseJSON2 parseJSON parseJSONList parseJSON parseJSONList
516647-- List functions
517648-------------------------------------------------------------------------------
518649
650+-- | Helper function to use with 'liftParseJSON'. See 'Data.Aeson.ToJSON.listEncoding'.
519651listParser :: (Value -> Parser a) -> Value -> Parser [a]
520652listParser f (Array xs) = fmap V.toList (V.mapM f xs)
521−listParser _ v = typeMismatch "[a]" v
653+listParser _ v = typeMismatch "Array" v
522654{-# INLINE listParser #-}
523655
524656-------------------------------------------------------------------------------
@@ -536,48 +668,139 @@ instance (FromJSON a) => FromJSON [a] where
536668-- Functions
537669-------------------------------------------------------------------------------
538670
539−-- | @withObject expected f value@ applies @f@ to the 'Object' when @value@ is an @Object@
540−-- 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"
541686withObject :: String -> (Object -> Parser a) -> Value -> Parser a
542−withObject _ f (Object obj) = f obj
543−withObject expected _ v = typeMismatch expected v
687+withObject _ f (Object obj) = f obj
688+withObject name _ v = prependContext name (typeMismatch "Object" v)
544689{-# INLINE withObject #-}
545690
546−-- | @withText expected f value@ applies @f@ to the 'Text' when @value@ is a @String@
547−-- 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"
548698withText :: String -> (Text -> Parser a) -> Value -> Parser a
549−withText _ f (String txt) = f txt
550−withText expected _ v = typeMismatch expected v
699+withText _ f (String txt) = f txt
700+withText name _ v = prependContext name (typeMismatch "String" v)
551701{-# INLINE withText #-}
552702
553−-- | @withArray expected f value@ applies @f@ to the 'Array' when @value@ is an @Array@
554−-- 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"
555710withArray :: String -> (Array -> Parser a) -> Value -> Parser a
556−withArray _ f (Array arr) = f arr
557−withArray expected _ v = typeMismatch expected v
711+withArray _ f (Array arr) = f arr
712+withArray name _ v = prependContext name (typeMismatch "Array" v)
558713{-# INLINE withArray #-}
559714
560−-- | @withNumber expected f value@ applies @f@ to the 'Number' when @value@ is a 'Number'.
561−-- and fails using @'typeMismatch' expected@ otherwise.
562−withNumber :: String -> (Number -> Parser a) -> Value -> Parser a
563−withNumber expected f = withScientific expected (f . scientificToNumber)
564−{-# INLINE withNumber #-}
565−{-# DEPRECATED withNumber "Use withScientific instead" #-}
566−
567−-- | @withScientific expected f value@ applies @f@ to the 'Scientific' number when @value@ is a 'Number'.
568−-- 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"
569728withScientific :: String -> (Scientific -> Parser a) -> Value -> Parser a
570−withScientific _ f (Number scientific) = f scientific
571−withScientific expected _ v = typeMismatch expected v
729+withScientific _ f (Number scientific) = f scientific
730+withScientific name _ v = prependContext name (typeMismatch "Number" v)
572731{-# INLINE withScientific #-}
573732
574−-- | @withBool expected f value@ applies @f@ to the 'Bool' when @value@ is a @Bool@
575−-- 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"
576789withBool :: String -> (Bool -> Parser a) -> Value -> Parser a
577−withBool _ f (Bool arr) = f arr
578−withBool expected _ v = typeMismatch expected v
790+withBool _ f (Bool arr) = f arr
791+withBool name _ v = prependContext name (typeMismatch "Boolean" v)
579792{-# INLINE withBool #-}
580793
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+
581804-- | Convert a value from JSON, failing if the types do not match.
582805fromJSON :: (FromJSON a) => Value -> Result a
583806fromJSON = parse parseJSON
@@ -596,32 +819,68 @@ ifromJSON = iparse parseJSON
596819-- in an object for it to be valid. If the key and value are
597820-- optional, use '.:?' instead.
598821(.:) :: (FromJSON a) => Object -> Text -> Parser a
599−obj .: key = case H.lookup key obj of
600− Nothing -> fail $ "key " ++ show key ++ " not present"
601− Just v -> parseJSON v <?> Key key
822+(.:) = explicitParseField parseJSON
602823{-# INLINE (.:) #-}
603824
604−-- | Retrieve the value associated with the given key of an 'Object'.
605−-- The result is 'Nothing' if the key is not present, or 'empty' if
606−-- 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.
607828--
608829-- This accessor is most useful if the key and value can be absent
609830-- from an object without affecting its validity. If the key and
610831-- value are mandatory, use '.:' instead.
611832(.:?) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
612−obj .:? key = case H.lookup key obj of
613− Nothing -> pure Nothing
614− Just v -> parseJSON v <?> Key key
833+(.:?) = explicitParseFieldMaybe parseJSON
615834{-# INLINE (.:?) #-}
616835
617−-- | Like '.:?', but the resulting parser will fail,
618−-- 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'.
619842(.:!) :: (FromJSON a) => Object -> Text -> Parser (Maybe a)
620−obj .:! key = case H.lookup key obj of
621− Nothing -> pure Nothing
622− Just v -> Just <$> parseJSON v <?> Key key
843+(.:!) = explicitParseFieldMaybe' parseJSON
623844{-# INLINE (.:!) #-}
624845
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 <$> p v <?> Key key
882+{-# INLINE explicitParseFieldMaybe' #-}
883+
625884-- | Helper for use in combination with '.:?' to provide default
626885-- values for optional JSON object fields.
627886--
@@ -644,317 +903,554 @@ pmval .!= val = fromMaybe val <$> pmval
644903-- Generic parseJSON
645904-------------------------------------------------------------------------------
646905
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+
647911instance OVERLAPPABLE_ (GFromJSON arity a) => GFromJSON arity (M1 i c a) where
648912 -- Meta-information, which is not handled elsewhere, is just added to the
649913 -- parsed value:
650− 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
651946
652947instance (FromJSON a) => GFromJSON arity (K1 i a) where
653948 -- Constant values are decoded using their FromJSON instance:
654− gParseJSON _opts _ _ _ = fmap K1 . parseJSON
949+ gParseJSON _opts _ = fmap K1 . parseJSON
655950
656951instance GFromJSON One Par1 where
657952 -- Direct occurrences of the last type parameter are decoded with the
658953 -- function passed in as an argument:
659− gParseJSON _opts _ pj _ = fmap Par1 . pj
954+ gParseJSON _opts (From1Args pj _) = fmap Par1 . pj
660955
661956instance (FromJSON1 f) => GFromJSON One (Rec1 f) where
662957 -- Recursive occurrences of the last type parameter are decoded using their
663958 -- FromJSON1 instance:
664− gParseJSON _opts _ pj pjl = fmap Rec1 . liftParseJSON pj pjl
665−
666−instance GFromJSON arity U1 where
667− -- Empty constructors are expected to be encoded as an empty array:
668− gParseJSON _opts _ _ _ v
669− | isEmptyArray v = pure U1
670− | otherwise = typeMismatch "unit constructor (U1)" v
671−
672−instance (ConsFromJSON arity a) => GFromJSON arity (C1 c a) where
673− -- Constructors need to be decoded differently depending on whether they're
674− -- a record or not. This distinction is made by consParseJSON:
675− gParseJSON opts pa pj pjl = fmap M1 . consParseJSON opts pa pj pjl
676−
677−instance ( FromProduct arity a, FromProduct arity b
678− , ProductSize a, ProductSize b
679− ) => GFromJSON arity (a :*: b) where
680− -- Products are expected to be encoded to an array. Here we check whether we
681− -- got an array of the same size as the product, then parse each of the
682− -- product's elements using parseProduct:
683− gParseJSON opts pa pj pjl = withArray "product (:*:)" $ \arr ->
684− let lenArray = V.length arr
685− lenProduct = (unTagged2 :: Tagged2 (a :*: b) Int -> Int)
686− productSize in
687− if lenArray == lenProduct
688− then parseProduct opts pa arr 0 lenProduct pj pjl
689− else fail $ "When expecting a product of " ++ show lenProduct ++
690− " values, encountered an Array of " ++ show lenArray ++
691− " elements instead"
692−
693−instance ( AllNullary (a :+: b) allNullary
694− , ParseSum arity (a :+: b) allNullary
695− ) => GFromJSON arity (a :+: b) where
696− -- If all constructors of a sum datatype are nullary and the
697− -- 'allNullaryToStringTag' option is set they are expected to be
698− -- encoded as strings. This distinction is made by 'parseSum':
699− gParseJSON opts pa pj pjl =
700− (unTagged :: Tagged allNullary (Parser ((a :+: b) d)) ->
701− (Parser ((a :+: b) d)))
702− . parseSum opts pa pj pjl
959+ gParseJSON _opts (From1Args pj pjl) = fmap Rec1 . liftParseJSON pj pjl
703960
704961instance (FromJSON1 f, GFromJSON One g) => GFromJSON One (f :.: g) where
705962 -- If an occurrence of the last type parameter is nested inside two
706963 -- composed types, it is decoded by using the outermost type's FromJSON1
707964 -- instance to generically decode the innermost type:
708− gParseJSON opts pa pj pjl =
709− let gpj = gParseJSON opts pa pj pjl in
710− 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
7111013
7121014--------------------------------------------------------------------------------
7131015
7141016class ParseSum arity f allNullary where
715− parseSum :: Options -> Proxy arity
716− -> (Value -> Parser a) -> (Value -> Parser [a])
717− -> Value -> Tagged allNullary (Parser (f a))
718−
719−instance ( SumFromString (a :+: b)
720− , FromPair arity (a :+: b)
721− , FromTaggedObject arity (a :+: b)
722− ) => ParseSum arity (a :+: b) True where
723− parseSum opts pa pj pjl
724− | allNullaryToStringTag opts = Tagged . parseAllNullarySum opts
725− | otherwise = Tagged . parseNonAllNullarySum opts pa pj pjl
726−
727−instance ( FromPair arity (a :+: b)
728− , FromTaggedObject arity (a :+: b)
729− ) => ParseSum arity (a :+: b) False where
730− 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
7311037
7321038--------------------------------------------------------------------------------
7331039
734−parseAllNullarySum :: SumFromString f => Options -> Value -> Parser (f a)
735−parseAllNullarySum opts = withText "Text" $ \key ->
736− maybe (notFound key) return $
737− 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])
7381062
7391063class SumFromString f where
740− parseSumFromString :: Options -> Text -> Maybe (f a)
1064+ parseSumFromString :: (String -> String) -> Text -> Maybe (f a)
7411065
7421066instance (SumFromString a, SumFromString b) => SumFromString (a :+: b) where
7431067 parseSumFromString opts key = (L1 <$> parseSumFromString opts key) <|>
7441068 (R1 <$> parseSumFromString opts key)
7451069
7461070instance (Constructor c) => SumFromString (C1 c U1) where
747− parseSumFromString opts key | key == name = Just $ M1 U1
748− | otherwise = Nothing
749− where
750− name = pack $ constructorTagModifier opts $
751− 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)
7521076
753−--------------------------------------------------------------------------------
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
7541111
755−parseNonAllNullarySum :: ( FromPair arity (a :+: b)
756− , FromTaggedObject arity (a :+: b)
757− ) => Options -> Proxy arity
758− -> (Value -> Parser c) -> (Value -> Parser [c])
759− -> Value -> Parser ((a :+: b) c)
760−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 :* _) =
7611121 case sumEncoding opts of
7621122 TaggedObject{..} ->
763− withObject "Object" $ \obj -> do
764− tag <- obj .: pack tagFieldName
765− fromMaybe (notFound tag) $
766− 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])
7671133
7681134 ObjectWithSingleField ->
769− withObject "Object" $ \obj ->
770− case H.toList obj of
771− [pair@(tag, _)] -> fromMaybe (notFound tag) $
772− parsePair opts pa pj pjl pair
773− _ -> 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
7741145
7751146 TwoElemArray ->
776− withArray "Array" $ \arr ->
777− if V.length arr == 2
778− then case V.unsafeIndex arr 0 of
779− String tag -> fromMaybe (notFound tag) $
780− parsePair opts pa pj pjl (tag, V.unsafeIndex arr 1)
781− _ -> fail "First element is not a String"
782− 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)
7831165
7841166--------------------------------------------------------------------------------
7851167
7861168class FromTaggedObject arity f where
787− parseFromTaggedObject :: Options -> Proxy arity
788− -> String -> Object
789− -> (Value -> Parser a) -> (Value -> Parser [a])
790− -> 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))
7911175
7921176instance ( FromTaggedObject arity a, FromTaggedObject arity b) =>
7931177 FromTaggedObject arity (a :+: b) where
794− parseFromTaggedObject opts pa contentsFieldName obj pj pjl tag =
795− (fmap L1 <$> parseFromTaggedObject opts pa contentsFieldName obj pj pjl tag) <|>
796− (fmap R1 <$> parseFromTaggedObject opts pa contentsFieldName obj pj pjl tag)
1178+ parseFromTaggedObject p obj =
1179+ (fmap L1 <$> parseFromTaggedObject p obj) <|>
1180+ (fmap R1 <$> parseFromTaggedObject p obj)
7971181
798−instance ( FromTaggedObject' arity f
1182+instance ( IsRecord f isRecord
1183+ , FromTaggedObject' arity f isRecord
7991184 , Constructor c
8001185 ) => FromTaggedObject arity (C1 c f) where
801− parseFromTaggedObject opts pa contentsFieldName obj pj pjl tag
802− | tag == name = Just $ M1 <$> parseFromTaggedObject'
803− opts pa contentsFieldName pj pjl obj
804− | otherwise = Nothing
805− where
806− name = pack $ constructorTagModifier opts $
807− 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)
8081195
8091196--------------------------------------------------------------------------------
8101197
811−class FromTaggedObject' arity f where
812− parseFromTaggedObject' :: Options -> Proxy arity -> String
813− -> (Value -> Parser a) -> (Value -> Parser [a])
814− -> Object -> Parser (f a)
815−
816−class FromTaggedObject'' arity f isRecord where
817− parseFromTaggedObject'' :: Options -> Proxy arity -> String
818− -> (Value -> Parser a) -> (Value -> Parser [a])
819− -> Object -> Tagged isRecord (Parser (f a))
820−
821−instance ( IsRecord f isRecord
822− , FromTaggedObject'' arity f isRecord
823− ) => FromTaggedObject' arity f where
824− parseFromTaggedObject' opts pa contentsFieldName pj pjl =
825− (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a)) .
826− parseFromTaggedObject'' opts pa contentsFieldName pj pjl
827−
828−instance (FromRecord arity f) => FromTaggedObject'' arity f True where
829− parseFromTaggedObject'' opts pa _ pj pjl =
830− Tagged . parseRecord opts pa Nothing pj pjl
831−
832−instance (GFromJSON arity f) => FromTaggedObject'' arity f False where
833− parseFromTaggedObject'' opts pa contentsFieldName pj pjl = Tagged .
834− (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
8351216
836−instance OVERLAPPING_ FromTaggedObject'' arity U1 False where
837− 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)
8381220
8391221--------------------------------------------------------------------------------
8401222
1223+-- | Constructors need to be decoded differently depending on whether they're
1224+-- a record or not. This distinction is made by 'ConsParseJSON'.
8411225class ConsFromJSON arity f where
842− consParseJSON :: Options -> Proxy arity
843− -> (Value -> Parser a) -> (Value -> Parser [a])
844− -> Value -> Parser (f a)
1226+ consParseJSON
1227+ :: ConName :* TypeName :* Options :* FromArgs arity a
1228+ -> Value -> Parser (f a)
8451229
8461230class ConsFromJSON' arity f isRecord where
847− consParseJSON' :: Options -> Proxy arity
848− -> (Maybe Text) -- ^ A dummy label
849− -- (Nothing to use proper label)
850− -> (Value -> Parser a) -> (Value -> Parser [a])
851− -> Value -> Tagged isRecord (Parser (f a))
1231+ consParseJSON'
1232+ :: ConName :* TypeName :* Options :* FromArgs arity a
1233+ -> Value -> Tagged isRecord (Parser (f a))
8521234
8531235instance ( IsRecord f isRecord
8541236 , ConsFromJSON' arity f isRecord
8551237 ) => ConsFromJSON arity f where
856− consParseJSON opts pa pj pjl v = let
857− (v2,lab) = case (unwrapUnaryRecords opts,isUnary (undefined :: f a)) of
858− -- use a dummy object with a dummy label
859− (True,True) -> ((object [(pack "dummy",v)]),Just $ pack "dummy")
860− _ ->(v,Nothing)
861− in (unTagged :: Tagged isRecord (Parser (f a)) -> Parser (f a))
862− $ consParseJSON' opts pa lab pj pjl v2
863−
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)
8641265
865−instance (FromRecord arity f) => ConsFromJSON' arity f True where
866− consParseJSON' opts pa mlab pj pjl = Tagged . (withObject "record (:*:)"
867− $ 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
8681270
869−instance (GFromJSON arity f) => ConsFromJSON' arity f False where
870− 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
8711274
8721275--------------------------------------------------------------------------------
8731276
874−class FromRecord arity f where
875− parseRecord :: Options -> Proxy arity
876− -> (Maybe Text) -- ^ A dummy label
877− -- (Nothing to use proper label)
878− -> (Value -> Parser a) -> (Value -> Parser [a])
879− -> Object -> Parser (f a)
880−
881−instance ( FromRecord arity a
882− , FromRecord arity b
883− ) => FromRecord arity (a :*: b) where
884− parseRecord opts pa _ pj pjl obj =
885− (:*:) <$> parseRecord opts pa Nothing pj pjl obj
886− <*> parseRecord opts pa Nothing pj pjl obj
887−
888−instance ( Selector s
889− , GFromJSON arity a
890− ) => FromRecord arity (S1 s a) where
891− parseRecord opts pa lab pj pjl =
892− (<?> Key label) . gParseJSON opts pa pj pjl <=< (.: label)
893− where
894− label = fromMaybe defLabel lab
895− defLabel = pack . fieldLabelModifier opts $
896− selName (undefined :: t s a p)
897−
898−instance OVERLAPPING_ (Selector s, FromJSON a) =>
899− FromRecord arity (S1 s (K1 i (Maybe a))) where
900− parseRecord _ _ (Just lab) _ _ obj = (M1 . K1) <$> obj .:? lab
901− parseRecord opts _ Nothing _ _ obj = (M1 . K1) <$> 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
9021298 where
903− label = fieldLabelModifier opts $
904− 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))
9051346
9061347--------------------------------------------------------------------------------
9071348
908−class FromProduct arity f where
909− 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
9101371 -> Array -> Int -> Int
911− -> (Value -> Parser a) -> (Value -> Parser [a])
9121372 -> Parser (f a)
9131373
914−instance ( FromProduct arity a
915− , FromProduct arity b
916− ) => FromProduct arity (a :*: b) where
917− parseProduct opts pa arr ix len pj pjl =
918− (:*:) <$> parseProduct opts pa arr ix lenL pj pjl
919− <*> parseProduct opts pa arr ixR lenR pj pjl
1374+instance ( ProductFromJSON arity a
1375+ , ProductFromJSON arity b
1376+ ) => ProductFromJSON arity (a :*: b) where
1377+ productParseJSON p arr ix len =
1378+ (:*:) <$> productParseJSON p arr ix lenL
1379+ <*> productParseJSON p arr ixR lenR
9201380 where
9211381 lenL = len `unsafeShiftR` 1
9221382 ixR = ix + lenL
9231383 lenR = len - lenL
9241384
925−instance (GFromJSON arity a) => FromProduct arity (S1 s a) where
926− parseProduct opts pa arr ix _ pj pjl =
927− 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 <$> gParseJSON opts fargs (V.unsafeIndex arr ix) <?> Index ix
9281388
9291389--------------------------------------------------------------------------------
9301390
9311391class FromPair arity f where
932− parsePair :: Options -> Proxy arity
933− -> (Value -> Parser a) -> (Value -> Parser [a])
934− -> Pair -> Maybe (Parser (f a))
1392+ -- The first component of the parameter tuple is the tag to match.
1393+ parsePair :: Text :* TypeName :* Options :* FromArgs arity a
1394+ -> Value
1395+ -> Maybe (Parser (f a))
9351396
9361397instance ( FromPair arity a
9371398 , FromPair arity b
9381399 ) => FromPair arity (a :+: b) where
939− parsePair opts pa pj pjl pair = (fmap L1 <$> parsePair opts pa pj pjl pair) <|>
940− (fmap R1 <$> parsePair opts pa pj pjl pair)
1400+ parsePair p pair =
1401+ (fmap L1 <$> parsePair p pair) <|>
1402+ (fmap R1 <$> parsePair p pair)
9411403
9421404instance ( Constructor c
943− , GFromJSON arity a
9441405 , ConsFromJSON arity a
9451406 ) => FromPair arity (C1 c a) where
946− parsePair opts pa pj pjl (tag, value)
947− | tag == tag' = Just $ gParseJSON opts pa pj pjl value
1407+ parsePair (tag :* p@(_ :* opts :* _)) v
1408+ | tag == tag' = Just $ M1 <$> consParseJSON (cname :* p) v
9481409 | otherwise = Nothing
949− where
950− tag' = pack $ constructorTagModifier opts $
951− conName (undefined :: t c a p)
1410+ where
1411+ tag' = pack $ constructorTagModifier opts cname
1412+ cname = conName (undefined :: M1 _i c _a _p)
9521413
9531414--------------------------------------------------------------------------------
9541415
955−notFound :: Text -> Parser a
956−notFound key = fail $ "The key \"" ++ unpack key ++ "\" was not found"
957−{-# 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
9581454
9591455-------------------------------------------------------------------------------
9601456-- Instances
@@ -1012,17 +1508,20 @@ instance (FromJSON a, FromJSON b) => FromJSON (Either a b) where
10121508 parseJSON = parseJSON2
10131509 {-# INLINE parseJSON #-}
10141510
1015−
1511+instance FromJSON Void where
1512+ parseJSON _ = fail "Cannot parse Void"
1513+ {-# INLINE parseJSON #-}
10161514
10171515instance FromJSON Bool where
1018− parseJSON = withBool "Bool" pure
1516+ parseJSON (Bool b) = pure b
1517+ parseJSON v = typeMismatch "Bool" v
10191518 {-# INLINE parseJSON #-}
10201519
10211520instance FromJSONKey Bool where
10221521 fromJSONKey = FromJSONKeyTextParser $ \t -> case t of
10231522 "true" -> pure True
10241523 "false" -> pure False
1025− _ -> fail $ "Cannot parse key into Bool: " ++ T.unpack t
1524+ _ -> fail $ "cannot parse key " ++ show t ++ " into Bool"
10261525
10271526instance FromJSON Ordering where
10281527 parseJSON = withText "Ordering" $ \s ->
@@ -1030,25 +1529,30 @@ instance FromJSON Ordering where
10301529 "LT" -> return LT
10311530 "EQ" -> return EQ
10321531 "GT" -> return GT
1033− _ -> fail "Parsing Ordering value failed: expected \"LT\", \"EQ\", or \"GT\""
1532+ _ -> fail $ "parsing Ordering failed, unexpected " ++ show s ++
1533+ " (expected \"LT\", \"EQ\", or \"GT\")"
10341534
10351535instance FromJSON () where
10361536 parseJSON = withArray "()" $ \v ->
10371537 if V.null v
10381538 then pure ()
1039− else fail "Expected an empty array"
1539+ else prependContext "()" $ fail "expected an empty array"
10401540 {-# INLINE parseJSON #-}
10411541
10421542instance FromJSON Char where
1043− parseJSON = withText "Char" $ \t ->
1044− if T.compareLength t 1 == EQ
1045− then pure $ T.head t
1046− else fail "Expected a string of length 1"
1543+ parseJSON = withText "Char" parseChar
10471544 {-# INLINE parseJSON #-}
10481545
1049− parseJSONList = withText "String" $ pure . T.unpack
1546+ parseJSONList (String s) = pure (T.unpack s)
1547+ parseJSONList v = typeMismatch "String" v
10501548 {-# INLINE parseJSONList #-}
10511549
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+
10521556instance FromJSON Double where
10531557 parseJSON = parseRealFloat "Double"
10541558 {-# INLINE parseJSON #-}
@@ -1060,12 +1564,6 @@ instance FromJSONKey Double where
10601564 "-Infinity" -> pure (negate 1/0)
10611565 _ -> Scientific.toRealFloat <$> parseScientificText t
10621566
1063−instance FromJSON Number where
1064− parseJSON (Number s) = pure $ scientificToNumber s
1065− parseJSON Null = pure (D (0/0))
1066− parseJSON v = typeMismatch "Number" v
1067− {-# INLINE parseJSON #-}
1068−
10691567instance FromJSON Float where
10701568 parseJSON = parseRealFloat "Float"
10711569 {-# INLINE parseJSON #-}
@@ -1078,112 +1576,133 @@ instance FromJSONKey Float where
10781576 _ -> Scientific.toRealFloat <$> parseScientificText t
10791577
10801578instance (FromJSON a, Integral a) => FromJSON (Ratio a) where
1081− parseJSON = withObject "Rational" $ \obj ->
1082− (%) <$> obj .: "numerator"
1083− <*> obj .: "denominator"
1084− {-# INLINE parseJSON #-}
1085−
1086−-- | /WARNING:/ Only parse fixed-precision numbers from trusted input
1087−-- since an attacker could easily fill up the memory of the target
1088−-- system by specifying a scientific number with a big exponent like
1089−-- @1e1000000000@.
1579+ parseJSON (Number x)
1580+ | exp10 <= 1024
1581+ , exp10 >= -1024 = return $! realToFrac x
1582+ | otherwise = prependContext "Ratio" $ fail msg
1583+ where
1584+ exp10 = base10Exponent x
1585+ msg = "found a number with exponent " ++ show exp10
1586+ ++ ", but it must not be greater than 1024 or less than -1024"
1587+ parseJSON o = objParser o
1588+ where
1589+ objParser = withObject "Rational" $ \obj -> do
1590+ numerator <- obj .: "numerator"
1591+ denominator <- obj .: "denominator"
1592+ if denominator == 0
1593+ then fail "Ratio denominator was 0"
1594+ else pure $ numerator % denominator
1595+ {-# INLINE parseJSON #-}
1596+
1597+-- | This instance includes a bounds check to prevent maliciously
1598+-- large inputs to fill up the memory of the target system. You can
1599+-- newtype 'Scientific' and provide your own instance using
1600+-- 'withScientific' if you want to allow larger inputs.
10901601instance HasResolution a => FromJSON (Fixed a) where
1091− parseJSON = withScientific "Fixed" $ pure . realToFrac
1602+ parseJSON = prependContext "Fixed" . withBoundedScientific' (pure . realToFrac)
10921603 {-# INLINE parseJSON #-}
10931604
10941605instance FromJSON Int where
1095− parseJSON = parseIntegral "Int"
1606+ parseJSON = parseBoundedIntegral "Int"
10961607 {-# INLINE parseJSON #-}
10971608
10981609instance FromJSONKey Int where
1099− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1610+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int"
11001611
1101−-- | /WARNING:/ Only parse Integers from trusted input since an
1102−-- attacker could easily fill up the memory of the target system by
1103−-- specifying a scientific number with a big exponent like
1104−-- @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.
11051616instance FromJSON Integer where
1106− parseJSON = withScientific "Integral" $ pure . truncate
1617+ parseJSON = parseIntegral "Integer"
11071618 {-# INLINE parseJSON #-}
11081619
11091620instance FromJSONKey Integer where
1110− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1621+ fromJSONKey = FromJSONKeyTextParser $ parseIntegralText "Integer"
11111622
11121623instance FromJSON Natural where
1113− parseJSON = withScientific "Natural" $ \s ->
1114− if Scientific.coefficient s < 0
1115− then fail $ "Expected a Natural number but got the negative number: " <> show s
1116− else pure $ truncate s
1624+ parseJSON value = do
1625+ integer <- parseIntegral "Natural" value
1626+ parseNatural integer
11171627
11181628instance FromJSONKey Natural where
1119− fromJSONKey = FromJSONKeyTextParser $ \t -> parseScientificText t >>= \s ->
1120− if Scientific.coefficient s < 0
1121− then fail $ "Expected a Natural number but got the negative number: " <> show s
1122− 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
11231639
11241640instance FromJSON Int8 where
1125− parseJSON = parseIntegral "Int8"
1641+ parseJSON = parseBoundedIntegral "Int8"
11261642 {-# INLINE parseJSON #-}
11271643
11281644instance FromJSONKey Int8 where
1129− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1645+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int8"
11301646
11311647instance FromJSON Int16 where
1132− parseJSON = parseIntegral "Int16"
1648+ parseJSON = parseBoundedIntegral "Int16"
11331649 {-# INLINE parseJSON #-}
11341650
11351651instance FromJSONKey Int16 where
1136− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1652+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int16"
11371653
11381654instance FromJSON Int32 where
1139− parseJSON = parseIntegral "Int32"
1655+ parseJSON = parseBoundedIntegral "Int32"
11401656 {-# INLINE parseJSON #-}
11411657
11421658instance FromJSONKey Int32 where
1143− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1659+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int32"
11441660
11451661instance FromJSON Int64 where
1146− parseJSON = parseIntegral "Int64"
1662+ parseJSON = parseBoundedIntegral "Int64"
11471663 {-# INLINE parseJSON #-}
11481664
11491665instance FromJSONKey Int64 where
1150− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1666+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Int64"
11511667
11521668instance FromJSON Word where
1153− parseJSON = parseIntegral "Word"
1669+ parseJSON = parseBoundedIntegral "Word"
11541670 {-# INLINE parseJSON #-}
11551671
11561672instance FromJSONKey Word where
1157− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1673+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word"
11581674
11591675instance FromJSON Word8 where
1160− parseJSON = parseIntegral "Word8"
1676+ parseJSON = parseBoundedIntegral "Word8"
11611677 {-# INLINE parseJSON #-}
11621678
11631679instance FromJSONKey Word8 where
1164− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1680+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word8"
11651681
11661682instance FromJSON Word16 where
1167− parseJSON = parseIntegral "Word16"
1683+ parseJSON = parseBoundedIntegral "Word16"
11681684 {-# INLINE parseJSON #-}
11691685
11701686instance FromJSONKey Word16 where
1171− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1687+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word16"
11721688
11731689instance FromJSON Word32 where
1174− parseJSON = parseIntegral "Word32"
1690+ parseJSON = parseBoundedIntegral "Word32"
11751691 {-# INLINE parseJSON #-}
11761692
11771693instance FromJSONKey Word32 where
1178− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1694+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word32"
11791695
11801696instance FromJSON Word64 where
1181− parseJSON = parseIntegral "Word64"
1697+ parseJSON = parseBoundedIntegral "Word64"
11821698 {-# INLINE parseJSON #-}
11831699
11841700instance FromJSONKey Word64 where
1185− fromJSONKey = FromJSONKeyTextParser parseIntegralText
1701+ fromJSONKey = FromJSONKeyTextParser $ parseBoundedIntegralText "Word64"
11861702
1703+instance FromJSON CTime where
1704+ parseJSON = fmap CTime . parseJSON
1705+ {-# INLINE parseJSON #-}
11871706
11881707instance FromJSON Text where
11891708 parseJSON = withText "Text" pure
@@ -1213,17 +1732,17 @@ parseVersionText = go . readP_to_S parseVersion . unpack
12131732 where
12141733 go [(v,[])] = return v
12151734 go (_ : xs) = go xs
1216− go _ = fail $ "could not parse Version"
1735+ go _ = fail "parsing Version failed"
12171736
12181737-------------------------------------------------------------------------------
12191738-- semigroups NonEmpty
12201739-------------------------------------------------------------------------------
12211740
12221741instance FromJSON1 NonEmpty where
1223− liftParseJSON p _ = withArray "NonEmpty a" $
1742+ liftParseJSON p _ = withArray "NonEmpty" $
12241743 (>>= ne) . Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
12251744 where
1226− ne [] = fail "Expected a NonEmpty but got an empty list"
1745+ ne [] = fail "parsing NonEmpty failed, unexpected empty list"
12271746 ne (x:xs) = pure (x :| xs)
12281747 {-# INLINE liftParseJSON #-}
12291748
@@ -1244,7 +1763,7 @@ instance FromJSON Scientific where
12441763-------------------------------------------------------------------------------
12451764
12461765instance FromJSON1 DList.DList where
1247− liftParseJSON p _ = withArray "DList a" $
1766+ liftParseJSON p _ = withArray "DList" $
12481767 fmap DList.fromList .
12491768 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
12501769 {-# INLINE liftParseJSON #-}
@@ -1271,7 +1790,7 @@ instance (FromJSON a) => FromJSON (Identity a) where
12711790 parseJSONList = liftParseJSONList parseJSON parseJSONList
12721791 {-# INLINE parseJSONList #-}
12731792
1274−instance (FromJSONKey a, FromJSON a) => FromJSONKey (Identity a) where
1793+instance (FromJSONKey a) => FromJSONKey (Identity a) where
12751794 fromJSONKey = coerceFromJSONKeyFunction (fromJSONKey :: FromJSONKeyFunction a)
12761795 fromJSONKeyList = coerceFromJSONKeyFunction (fromJSONKeyList :: FromJSONKeyFunction [a])
12771796
@@ -1321,7 +1840,7 @@ instance (FromJSON1 f, FromJSON1 g) => FromJSON1 (Sum f g) where
13211840 inr = "InR"
13221841
13231842 liftParseJSON _ _ _ = fail $
1324− "expected an object with a single property " ++
1843+ "parsing Sum failed, expected an object with a single property " ++
13251844 "where the property key should be either " ++
13261845 "\"InL\" or \"InR\""
13271846 {-# INLINE liftParseJSON #-}
@@ -1335,7 +1854,7 @@ instance (FromJSON1 f, FromJSON1 g, FromJSON a) => FromJSON (Sum f g a) where
13351854-------------------------------------------------------------------------------
13361855
13371856instance FromJSON1 Seq.Seq where
1338− liftParseJSON p _ = withArray "Seq a" $
1857+ liftParseJSON p _ = withArray "Seq" $
13391858 fmap Seq.fromList .
13401859 Tr.sequence . zipWith (parseIndexedJSON p) [0..] . V.toList
13411860 {-# INLINE liftParseJSON #-}
@@ -1369,15 +1888,15 @@ instance FromJSON a => FromJSON (IntMap.IntMap a) where
13691888
13701889instance (FromJSONKey k, Ord k) => FromJSON1 (M.Map k) where
13711890 liftParseJSON p _ = case fromJSONKey of
1372− FromJSONKeyCoerce _-> withObject "Map k v" $
1891+ FromJSONKeyCoerce _ -> withObject "Map" $
13731892 fmap (H.foldrWithKey (M.insert . unsafeCoerce) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1374− FromJSONKeyText f -> withObject "Map k v" $
1893+ FromJSONKeyText f -> withObject "Map" $
13751894 fmap (H.foldrWithKey (M.insert . f) M.empty) . H.traverseWithKey (\k v -> p v <?> Key k)
1376− FromJSONKeyTextParser f -> withObject "Map k v" $
1895+ FromJSONKeyTextParser f -> withObject "Map" $
13771896 H.foldrWithKey (\k v m -> M.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure M.empty)
1378− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1379− M.fromList <$> (Tr.sequence .
1380− zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr)
1897+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
1898+ fmap M.fromList . Tr.sequence .
1899+ zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
13811900 {-# INLINE liftParseJSON #-}
13821901
13831902instance (FromJSONKey k, Ord k, FromJSON v) => FromJSON (M.Map k v) where
@@ -1397,12 +1916,24 @@ instance (FromJSON v) => FromJSON (Tree.Tree v) where
13971916 parseJSON = parseJSON1
13981917 {-# INLINE parseJSON #-}
13991918
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+
14001931-------------------------------------------------------------------------------
14011932-- vector
14021933-------------------------------------------------------------------------------
14031934
14041935instance FromJSON1 Vector where
1405− liftParseJSON p _ = withArray "Vector a" $
1936+ liftParseJSON p _ = withArray "Vector" $
14061937 V.mapM (uncurry $ parseIndexedJSON p) . V.indexed
14071938 {-# INLINE liftParseJSON #-}
14081939
@@ -1416,14 +1947,14 @@ vectorParseJSON s = withArray s $ fmap V.convert . V.mapM (uncurry $ parseIndexe
14161947{-# INLINE vectorParseJSON #-}
14171948
14181949instance (Storable a, FromJSON a) => FromJSON (VS.Vector a) where
1419− parseJSON = vectorParseJSON "Data.Vector.Storable.Vector a"
1950+ parseJSON = vectorParseJSON "Data.Vector.Storable.Vector"
14201951
14211952instance (VP.Prim a, FromJSON a) => FromJSON (VP.Vector a) where
1422− parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector a"
1953+ parseJSON = vectorParseJSON "Data.Vector.Primitive.Vector"
14231954 {-# INLINE parseJSON #-}
14241955
14251956instance (VG.Vector VU.Vector a, FromJSON a) => FromJSON (VU.Vector a) where
1426− parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector a"
1957+ parseJSON = vectorParseJSON "Data.Vector.Unboxed.Vector"
14271958 {-# INLINE parseJSON #-}
14281959
14291960-------------------------------------------------------------------------------
@@ -1437,15 +1968,15 @@ instance (Eq a, Hashable a, FromJSON a) => FromJSON (HashSet.HashSet a) where
14371968
14381969instance (FromJSONKey k, Eq k, Hashable k) => FromJSON1 (H.HashMap k) where
14391970 liftParseJSON p _ = case fromJSONKey of
1440− FromJSONKeyCoerce _ -> withObject "HashMap ~Text v" $
1971+ FromJSONKeyCoerce _ -> withObject "HashMap ~Text" $
14411972 uc . H.traverseWithKey (\k v -> p v <?> Key k)
1442− FromJSONKeyText f -> withObject "HashMap k v" $
1973+ FromJSONKeyText f -> withObject "HashMap" $
14431974 fmap (mapKey f) . H.traverseWithKey (\k v -> p v <?> Key k)
1444− FromJSONKeyTextParser f -> withObject "HashMap k v" $
1975+ FromJSONKeyTextParser f -> withObject "HashMap" $
14451976 H.foldrWithKey (\k v m -> H.insert <$> f k <?> Key k <*> p v <?> Key k <*> m) (pure H.empty)
1446− FromJSONKeyValue f -> withArray "Map k v" $ \arr ->
1447− H.fromList <$> (Tr.sequence .
1448− zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr)
1977+ FromJSONKeyValue f -> withArray "Map" $ \arr ->
1978+ fmap H.fromList . Tr.sequence .
1979+ zipWith (parseIndexedJSONPair f p) [0..] . V.toList $ arr
14491980 where
14501981 uc :: Parser (H.HashMap Text v) -> Parser (H.HashMap k v)
14511982 uc = unsafeCoerce
@@ -1466,11 +1997,33 @@ instance FromJSON DotNetTime where
14661997 parseJSON = withText "DotNetTime" $ \t ->
14671998 let (s,m) = T.splitAt (T.length t - 5) t
14681999 t' = T.concat [s,".",m]
1469− in case parseTime defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
2000+ in case parseTimeM True defaultTimeLocale "/Date(%s%Q)/" (unpack t') of
14702001 Just d -> pure (DotNetTime d)
14712002 _ -> fail "could not parse .NET time"
14722003 {-# INLINE parseJSON #-}
14732004
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+
14742027-------------------------------------------------------------------------------
14752028-- time
14762029-------------------------------------------------------------------------------
@@ -1496,6 +2049,17 @@ instance FromJSONKey LocalTime where
14962049 fromJSONKey = FromJSONKeyTextParser (Time.run Time.localTime)
14972050
14982051
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.
14992063instance FromJSON ZonedTime where
15002064 parseJSON = withText "ZonedTime" (Time.run Time.zonedTime)
15012065
@@ -1510,41 +2074,168 @@ instance FromJSONKey UTCTime where
15102074 fromJSONKey = FromJSONKeyTextParser (Time.run Time.utcTime)
15112075
15122076
1513−-- | /WARNING:/ Only parse lengths of time from trusted input
1514−-- since an attacker could easily fill up the memory of the target
1515−-- system by specifying a scientific number with a big exponent like
1516−-- @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.
15172081instance FromJSON NominalDiffTime where
1518− 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
15192092 {-# INLINE parseJSON #-}
15202093
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+ <$> obj .: "months"
2109+ <*> obj .: "days"
2110+
2111+instance FromJSON DayOfWeek where
2112+ parseJSON = withText "DaysOfWeek" parseDayOfWeek
2113+
2114+parseDayOfWeek :: T.Text -> Parser DayOfWeek
2115+parseDayOfWeek t = case T.toLower t of
2116+ "monday" -> return Monday
2117+ "tuesday" -> return Tuesday
2118+ "wednesday" -> return Wednesday
2119+ "thursday" -> return Thursday
2120+ "friday" -> return Friday
2121+ "saturday" -> return Saturday
2122+ "sunday" -> return Sunday
2123+ _ -> fail "Invalid week day"
2124+
2125+instance FromJSONKey DayOfWeek where
2126+ fromJSONKey = FromJSONKeyTextParser parseDayOfWeek
2127+
15212128-------------------------------------------------------------------------------
15222129-- base Monoid/Semigroup
15232130-------------------------------------------------------------------------------
15242131
1525−instance FromJSON1 Dual where
1526− liftParseJSON p _ = fmap Dual . p
2132+instance FromJSON1 Monoid.Dual where
2133+ liftParseJSON p _ = fmap Monoid.Dual . p
2134+ {-# INLINE liftParseJSON #-}
2135+
2136+instance FromJSON a => FromJSON (Monoid.Dual a) where
2137+ parseJSON = parseJSON1
2138+ {-# INLINE parseJSON #-}
2139+
2140+
2141+instance FromJSON1 Monoid.First where
2142+ liftParseJSON p p' = fmap Monoid.First . liftParseJSON p p'
2143+ {-# INLINE liftParseJSON #-}
2144+
2145+instance FromJSON a => FromJSON (Monoid.First a) where
2146+ parseJSON = parseJSON1
2147+ {-# INLINE parseJSON #-}
2148+
2149+
2150+instance FromJSON1 Monoid.Last where
2151+ liftParseJSON p p' = fmap Monoid.Last . liftParseJSON p p'
2152+ {-# INLINE liftParseJSON #-}
2153+
2154+instance FromJSON a => FromJSON (Monoid.Last a) where
2155+ parseJSON = parseJSON1
2156+ {-# INLINE parseJSON #-}
2157+
2158+
2159+instance FromJSON1 Semigroup.Min where
2160+ liftParseJSON p _ a = Semigroup.Min <$> p a
15272161 {-# INLINE liftParseJSON #-}
15282162
1529−instance FromJSON a => FromJSON (Dual a) where
2163+ liftParseJSONList _ p a = fmap Semigroup.Min <$> p a
2164+ {-# INLINE liftParseJSONList #-}
2165+
2166+instance (FromJSON a) => FromJSON (Semigroup.Min a) where
15302167 parseJSON = parseJSON1
15312168 {-# INLINE parseJSON #-}
15322169
2170+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2171+ {-# INLINE parseJSONList #-}
15332172
1534−instance FromJSON1 First where
1535− liftParseJSON p p' = fmap First . liftParseJSON p p'
2173+
2174+instance FromJSON1 Semigroup.Max where
2175+ liftParseJSON p _ a = Semigroup.Max <$> p a
15362176 {-# INLINE liftParseJSON #-}
15372177
1538−instance FromJSON a => FromJSON (First a) where
2178+ liftParseJSONList _ p a = fmap Semigroup.Max <$> p a
2179+ {-# INLINE liftParseJSONList #-}
2180+
2181+instance (FromJSON a) => FromJSON (Semigroup.Max a) where
15392182 parseJSON = parseJSON1
15402183 {-# INLINE parseJSON #-}
15412184
2185+ parseJSONList = liftParseJSONList parseJSON parseJSONList
2186+ {-# INLINE parseJSONList #-}
2187+
15422188
1543−instance FromJSON1 Last where
1544− liftParseJSON p p' = fmap Last . liftParseJSON p p'
2189+instance FromJSON1 Semigroup.First where
2190+ liftParseJSON p _ a = Semigroup.First <$> p a
15452191 {-# INLINE liftParseJSON #-}
15462192
1547−instance FromJSON a => FromJSON (Last a) where
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
15482239 parseJSON = parseJSON1
15492240 {-# INLINE parseJSON #-}
15502241
@@ -1552,11 +2243,21 @@ instance FromJSON a => FromJSON (Last a) where
15522243-- tagged
15532244-------------------------------------------------------------------------------
15542245
2246+instance FromJSON1 Proxy where
2247+ {-# INLINE liftParseJSON #-}
2248+ liftParseJSON _ _ = fromNull "Proxy" Proxy
2249+
15552250instance FromJSON (Proxy a) where
15562251 {-# INLINE parseJSON #-}
1557− parseJSON Null = pure Proxy
1558− parseJSON v = typeMismatch "Proxy" v
2252+ parseJSON = fromNull "Proxy" Proxy
15592253
2254+fromNull :: String -> a -> Value -> Parser a
2255+fromNull _ a Null = pure a
2256+fromNull c _ v = prependContext c (typeMismatch "Null" v)
2257+
2258+instance FromJSON2 Tagged where
2259+ liftParseJSON2 _ _ p _ = fmap Tagged . p
2260+ {-# INLINE liftParseJSON2 #-}
15602261
15612262instance FromJSON1 (Tagged a) where
15622263 liftParseJSON p _ = fmap Tagged . p
@@ -1579,10 +2280,7 @@ instance (FromJSON a, FromJSON b, FromJSON c) => FromJSONKey (a,b,c)
15792280instance (FromJSON a, FromJSON b, FromJSON c, FromJSON d) => FromJSONKey (a,b,c,d)
15802281
15812282instance FromJSONKey Char where
1582− fromJSONKey = FromJSONKeyTextParser $ \t ->
1583− if T.length t == 1
1584− then return (T.index t 0)
1585− else typeMismatch "Expected Char but String didn't contain exactly one character" (String t)
2283+ fromJSONKey = FromJSONKeyTextParser parseChar
15862284 fromJSONKeyList = FromJSONKeyText T.unpack
15872285
15882286instance (FromJSONKey a, FromJSON a) => FromJSONKey [a] where
@@ -1592,7 +2290,7 @@ instance (FromJSONKey a, FromJSON a) => FromJSONKey [a] where
15922290-- Tuple instances, see tuple-instances-from.hs
15932291-------------------------------------------------------------------------------
15942292
1595−instance FromJSON2 ((,) ) where
2293+instance FromJSON2 (,) where
15962294 liftParseJSON2 pA _ pB _ = withArray "(a, b)" $ \t ->
15972295 let n = V.length t
15982296 in if n == 2