Copyright	(c) 2011-2016 Bryan O'Sullivan (c) 2011 MailRank Inc.
License	BSD3
Maintainer	Bryan O'Sullivan <bos@serpentine.com>
Stability	experimental
Portability	portable
Safe Haskell	None
Language	Haskell2010

Data.Aeson.Parser.Internal

Contents

Lazy parsers
Strict parsers
Helpers
- Handling objects with duplicate keys

Description

Efficiently and correctly parse a JSON string. The string must be encoded as UTF-8.

Synopsis

json :: Parser Value
jsonEOF :: Parser Value
jsonWith :: ([( Key , Value )] -> Either String Object ) -> Parser Value
jsonLast :: Parser Value
jsonAccum :: Parser Value
jsonNoDup :: Parser Value
value :: Parser Value
jstring :: Parser Text
jstring_ :: Parser Text
scientific :: Parser Scientific
json' :: Parser Value
jsonEOF' :: Parser Value
jsonWith' :: ([( Key , Value )] -> Either String Object ) -> Parser Value
jsonLast' :: Parser Value
jsonAccum' :: Parser Value
jsonNoDup' :: Parser Value
value' :: Parser Value
decodeWith :: Parser Value -> ( Value -> Result a) -> ByteString -> Maybe a
decodeStrictWith :: Parser Value -> ( Value -> Result a) -> ByteString -> Maybe a
eitherDecodeWith :: Parser Value -> ( Value -> IResult a) -> ByteString -> Either ( JSONPath , String ) a
eitherDecodeStrictWith :: Parser Value -> ( Value -> IResult a) -> ByteString -> Either ( JSONPath , String ) a
fromListAccum :: [( Key , Value )] -> Object
parseListNoDup :: [( Key , Value )] -> Either String Object

Lazy parsers

json :: Parser Value Source #

Parse any JSON value.

The conversion of a parsed value to a Haskell value is deferred until the Haskell value is needed. This may improve performance if only a subset of the results of conversions are needed, but at a cost in thunk allocation.

This function is an alias for value . In aeson 0.8 and earlier, it parsed only object or array types, in conformance with the now-obsolete RFC 4627.

Warning

If an object contains duplicate keys, only the first one will be kept. For a more flexible alternative, see jsonWith .

jsonEOF :: Parser Value Source #

Parse a top-level JSON value followed by optional whitespace and end-of-input. See also: json .

jsonWith :: ([( Key , Value )] -> Either String Object ) -> Parser Value Source #

Parse any JSON value.

This parser is parameterized by a function to construct an Object from a raw list of key-value pairs, where duplicates are preserved. The pairs appear in reverse order from the source.

Examples

Expand

json keeps only the first occurence of each key, using fromList .

json = jsonWith (Right . fromList)

jsonLast keeps the last occurence of each key, using fromListWith ( const id ) .

jsonLast = jsonWith (Right . fromListWith (const id))

jsonAccum keeps wraps all values in arrays to keep duplicates, using fromListAccum .

jsonAccum = jsonWith (Right . fromListAccum)

jsonNoDup fails if any object contains duplicate keys, using parseListNoDup .

jsonNoDup = jsonWith parseListNoDup

jsonLast :: Parser Value Source #

Variant of json which keeps only the last occurence of every key.

jsonAccum :: Parser Value Source #

Variant of json wrapping all object mappings in Array to preserve key-value pairs with the same keys.

jsonNoDup :: Parser Value Source #

Variant of json which fails if any object contains duplicate keys.

value :: Parser Value Source #

Parse any JSON value. Synonym of json .

jstring :: Parser Text Source #

Parse a quoted JSON string.

jstring_ :: Parser Text Source #

Parse a string without a leading quote.

scientific :: Parser Scientific Source #

Parse a JSON number.

Strict parsers

json' :: Parser Value Source #

Parse any JSON value.

This is a strict version of json which avoids building up thunks during parsing; it performs all conversions immediately. Prefer this version if most of the JSON data needs to be accessed.

This function is an alias for value' . In aeson 0.8 and earlier, it parsed only object or array types, in conformance with the now-obsolete RFC 4627.

Warning

If an object contains duplicate keys, only the first one will be kept. For a more flexible alternative, see jsonWith' .

jsonEOF' :: Parser Value Source #

Parse a top-level JSON value followed by optional whitespace and end-of-input. See also: json' .

jsonWith' :: ([( Key , Value )] -> Either String Object ) -> Parser Value Source #

Strict version of jsonWith .

jsonLast' :: Parser Value Source #

Variant of json' which keeps only the last occurence of every key.

jsonAccum' :: Parser Value Source #

Variant of json' wrapping all object mappings in Array to preserve key-value pairs with the same keys.

jsonNoDup' :: Parser Value Source #

Variant of json' which fails if any object contains duplicate keys.

value' :: Parser Value Source #

Strict version of value . Synonym of json' .

Helpers

decodeWith :: Parser Value -> ( Value -> Result a) -> ByteString -> Maybe a Source #

decodeStrictWith :: Parser Value -> ( Value -> Result a) -> ByteString -> Maybe a Source #

eitherDecodeWith :: Parser Value -> ( Value -> IResult a) -> ByteString -> Either ( JSONPath , String ) a Source #

eitherDecodeStrictWith :: Parser Value -> ( Value -> IResult a) -> ByteString -> Either ( JSONPath , String ) a Source #

Handling objects with duplicate keys

fromListAccum :: [( Key , Value )] -> Object Source #

fromListAccum kvs is an object mapping keys to arrays containing all associated values from the original list kvs .

>>> fromListAccum [("apple", Bool True), ("apple", Bool False), ("orange", Bool False)]
fromList [("apple",Array [Bool False,Bool True]),("orange",Array [Bool False])]

parseListNoDup :: [( Key , Value )] -> Either String Object Source #

fromListNoDup kvs fails if kvs contains duplicate keys.