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|
(.module: {#.doc "Functionality for reading and writing values in the JSON format.
For more information, please see: http://www.json.org/"}
[lux #- Array]
(lux (control [monad #+ do Monad]
[eq #+ Eq]
codec
["p" parser "parser/" Monad<Parser>])
(data [bool]
[text "text/" Eq<Text> Monoid<Text>]
(text ["l" lexer])
[number "frac/" Codec<Text,Frac> "nat/" Codec<Text,Nat>]
[maybe]
["e" error]
[sum]
[product]
(coll [list "list/" Fold<List> Monad<List>]
[sequence #+ Sequence sequence "sequence/" Monad<Sequence>]
[dict #+ Dict]))
[macro #+ Monad<Meta> with-gensyms]
(macro ["s" syntax #+ syntax:]
[code]
[poly #+ poly:])
(lang [type])
))
(do-template [<name> <type>]
[(type: #export <name> <type>)]
[Null Unit]
[Boolean Bool]
[Number Frac]
[String Text]
)
(type: #export #rec JSON
(#Null Null)
(#Boolean Boolean)
(#Number Number)
(#String String)
(#Array (Sequence JSON))
(#Object (Dict String JSON)))
(do-template [<name> <type>]
[(type: #export <name> <type>)]
[Array (Sequence JSON)]
[Object (Dict String JSON)]
)
(type: #export (Reader a)
{#.doc "JSON reader."}
(p.Parser (List JSON) a))
(syntax: #export (json token)
{#.doc (doc "A simple way to produce JSON literals."
(json true)
(json 123.456)
(json "Some text")
(json #null)
(json ["this" "is" "an" "array"])
(json {"this" "is"
"an" "object"}))}
(let [(^open) Monad<Meta>
wrapper (function [x] (` (..json (~ x))))]
(case token
(^template [<ast-tag> <ctor> <json-tag>]
[_ (<ast-tag> value)]
(wrap (list (` (: JSON (<json-tag> (~ (<ctor> value))))))))
([#.Bool code.bool #Boolean]
[#.Frac code.frac #Number]
[#.Text code.text #String])
[_ (#.Tag ["" "null"])]
(wrap (list (` (: JSON #Null))))
[_ (#.Tuple members)]
(wrap (list (` (: JSON (#Array (sequence (~+ (list/map wrapper members))))))))
[_ (#.Record pairs)]
(do Monad<Meta>
[pairs' (monad.map @
(function [[slot value]]
(case slot
[_ (#.Text key-name)]
(wrap (` [(~ (code.text key-name)) (~ (wrapper value))]))
_
(macro.fail "Wrong syntax for JSON object.")))
pairs)]
(wrap (list (` (: JSON (#Object (dict.from-list text.Hash<Text> (list (~+ pairs')))))))))
_
(wrap (list token))
)))
(def: #export (get-fields json)
{#.doc "Get all the fields in a JSON object."}
(-> JSON (e.Error (List String)))
(case json
(#Object obj)
(#e.Success (dict.keys obj))
_
(#e.Error ($_ text/compose "Cannot get the fields of a non-object."))))
(def: #export (get key json)
{#.doc "A JSON object field getter."}
(-> String JSON (e.Error JSON))
(case json
(#Object obj)
(case (dict.get key obj)
(#.Some value)
(#e.Success value)
#.None
(#e.Error ($_ text/compose "Missing field \"" key "\" on object.")))
_
(#e.Error ($_ text/compose "Cannot get field \"" key "\" of a non-object."))))
(def: #export (set key value json)
{#.doc "A JSON object field setter."}
(-> String JSON JSON (e.Error JSON))
(case json
(#Object obj)
(#e.Success (#Object (dict.put key value obj)))
_
(#e.Error ($_ text/compose "Cannot set field \"" key "\" of a non-object."))))
(do-template [<name> <tag> <type> <desc>]
[(def: #export (<name> key json)
{#.doc (code.text ($_ text/compose "A JSON object field getter for " <desc> "."))}
(-> Text JSON (e.Error <type>))
(case (get key json)
(#e.Success (<tag> value))
(#e.Success value)
(#e.Success _)
(#e.Error ($_ text/compose "Wrong value type at key: " key))
(#e.Error error)
(#e.Error error)))]
[get-boolean #Boolean Boolean "booleans"]
[get-number #Number Number "numbers"]
[get-string #String String "strings"]
[get-array #Array Array "arrays"]
[get-object #Object Object "objects"]
)
(struct: #export _ (Eq JSON)
(def: (= x y)
(case [x y]
[#Null #Null]
true
(^template [<tag> <struct>]
[(<tag> x') (<tag> y')]
(:: <struct> = x' y'))
([#Boolean bool.Eq<Bool>]
[#Number number.Eq<Frac>]
[#String text.Eq<Text>])
[(#Array xs) (#Array ys)]
(and (n/= (sequence.size xs) (sequence.size ys))
(list/fold (function [idx prev]
(and prev
(maybe.default false
(do maybe.Monad<Maybe>
[x' (sequence.nth idx xs)
y' (sequence.nth idx ys)]
(wrap (= x' y'))))))
true
(list.indices (sequence.size xs))))
[(#Object xs) (#Object ys)]
(and (n/= (dict.size xs) (dict.size ys))
(list/fold (function [[xk xv] prev]
(and prev
(case (dict.get xk ys)
#.None false
(#.Some yv) (= xv yv))))
true
(dict.entries xs)))
_
false)))
############################################################
############################################################
############################################################
(def: unconsumed-input-error Text "Unconsumed JSON.")
(def: #export (run json parser)
(All [a] (-> JSON (Reader a) (e.Error a)))
(case (p.run (list json) parser)
(#e.Success [remainder output])
(case remainder
#.Nil
(#e.Success output)
_
(#e.Error unconsumed-input-error))
(#e.Error error)
(#e.Error error)))
(def: #export (fail error)
(All [a] (-> Text (Reader a)))
(function [inputs]
(#e.Error error)))
(def: #export any
{#.doc "Just returns the JSON input without applying any logic."}
(Reader JSON)
(<| (function [inputs])
(case inputs
#.Nil
(#e.Error "Empty JSON stream.")
(#.Cons head tail)
(#e.Success [tail head]))))
(do-template [<name> <type> <tag> <desc>]
[(def: #export <name>
{#.doc (code.text ($_ text/compose "Reads a JSON value as " <desc> "."))}
(Reader <type>)
(do p.Monad<Parser>
[head any]
(case head
(<tag> value)
(wrap value)
_
(fail ($_ text/compose "JSON value is not " <desc> ".")))))]
[null Unit #Null "null"]
[boolean Bool #Boolean "boolean"]
[number Frac #Number "number"]
[string Text #String "string"]
)
(do-template [<test> <check> <type> <eq> <encoder> <tag> <desc> <pre>]
[(def: #export (<test> test)
{#.doc (code.text ($_ text/compose "Asks whether a JSON value is a " <desc> "."))}
(-> <type> (Reader Bool))
(do p.Monad<Parser>
[head any]
(case head
(<tag> value)
(wrap (:: <eq> = test (<pre> value)))
_
(fail ($_ text/compose "JSON value is not " <desc> ".")))))
(def: #export (<check> test)
{#.doc (code.text ($_ text/compose "Ensures a JSON value is a " <desc> "."))}
(-> <type> (Reader Unit))
(do p.Monad<Parser>
[head any]
(case head
(<tag> value)
(let [value (<pre> value)]
(if (:: <eq> = test value)
(wrap [])
(fail ($_ text/compose "Value mismatch: " (<encoder> test) "=/=" (<encoder> value)))))
_
(fail ($_ text/compose "JSON value is not a " <desc> ".")))))]
[boolean? boolean! Bool bool.Eq<Bool> (:: bool.Codec<Text,Bool> encode) #Boolean "boolean" id]
[number? number! Frac number.Eq<Frac> (:: number.Codec<Text,Frac> encode) #Number "number" id]
[string? string! Text text.Eq<Text> text.encode #String "string" id]
)
(def: #export (nullable parser)
(All [a] (-> (Reader a) (Reader (Maybe a))))
(p.alt null
parser))
(def: #export (array parser)
{#.doc "Parses a JSON array, assuming that every element can be parsed the same way."}
(All [a] (-> (Reader a) (Reader a)))
(do p.Monad<Parser>
[head any]
(case head
(#Array values)
(case (p.run (sequence.to-list values) parser)
(#e.Error error)
(fail error)
(#e.Success [remainder output])
(case remainder
#.Nil
(wrap output)
_
(fail unconsumed-input-error)))
_
(fail "JSON value is not an array."))))
(def: #export (object parser)
{#.doc "Parses a JSON object, assuming that every element can be parsed the same way."}
(All [a] (-> (Reader a) (Reader (Dict Text a))))
(do p.Monad<Parser>
[head any]
(case head
(#Object object)
(case (do e.Monad<Error>
[]
(|> (dict.entries object)
(monad.map @ (function [[key val]]
(do @
[val (run val parser)]
(wrap [key val]))))
(:: @ map (dict.from-list text.Hash<Text>))))
(#e.Success table)
(wrap table)
(#e.Error error)
(fail error))
_
(fail "JSON value is not an array."))))
(def: #export (field field-name parser)
{#.doc "Parses a field inside a JSON object."}
(All [a] (-> Text (Reader a) (Reader a)))
(do p.Monad<Parser>
[head any]
(case head
(#Object object)
(case (dict.get field-name object)
(#.Some value)
(case (run value parser)
(#e.Success output)
(function [tail]
(#e.Success [(#.Cons (#Object (dict.remove field-name object))
tail)
output]))
(#e.Error error)
(fail error))
_
(fail ($_ text/compose "JSON object does not have field \"" field-name "\".")))
_
(fail "JSON value is not an object."))))
############################################################
############################################################
############################################################
(def: #hidden (show-null _) (-> Null Text) "null")
(do-template [<name> <type> <codec>]
[(def: <name> (-> <type> Text) <codec>)]
[show-boolean Boolean (:: bool.Codec<Text,Bool> encode)]
[show-number Number (:: number.Codec<Text,Frac> encode)]
[show-string String text.encode])
(def: (show-array show-json elems)
(-> (-> JSON Text) (-> Array Text))
($_ text/compose "["
(|> elems (sequence/map show-json) sequence.to-list (text.join-with ","))
"]"))
(def: (show-object show-json object)
(-> (-> JSON Text) (-> Object Text))
($_ text/compose "{"
(|> object
dict.entries
(list/map (function [[key value]] ($_ text/compose (show-string key) ":" (show-json value))))
(text.join-with ","))
"}"))
(def: (show-json json)
(-> JSON Text)
(case json
(^template [<tag> <show>]
(<tag> value)
(<show> value))
([#Null show-null]
[#Boolean show-boolean]
[#Number show-number]
[#String show-string]
[#Array (show-array show-json)]
[#Object (show-object show-json)])
))
(def: space~
(l.Lexer Text)
(l.some l.space))
(def: data-sep
(l.Lexer [Text Unit Text])
($_ p.seq space~ (l.this ",") space~))
(def: null~
(l.Lexer Null)
(do p.Monad<Parser>
[_ (l.this "null")]
(wrap [])))
(do-template [<name> <token> <value>]
[(def: <name>
(l.Lexer Boolean)
(do p.Monad<Parser>
[_ (l.this <token>)]
(wrap <value>)))]
[t~ "true" true]
[f~ "false" false]
)
(def: boolean~
(l.Lexer Boolean)
(p.either t~ f~))
(def: number~
(l.Lexer Number)
(do p.Monad<Parser>
[signed? (l.this? "-")
digits (l.many l.decimal)
decimals (p.default "0"
(do @
[_ (l.this ".")]
(l.many l.decimal)))
exp (p.default ""
(do @
[mark (l.one-of "eE")
signed?' (l.this? "-")
offset (l.many l.decimal)]
(wrap ($_ text/compose mark (if signed?' "-" "") offset))))]
(case (frac/decode ($_ text/compose (if signed? "-" "") digits "." decimals exp))
(#e.Error message)
(p.fail message)
(#e.Success value)
(wrap value))))
(def: escaped~
(l.Lexer Text)
($_ p.either
(p.after (l.this "\\t") (parser/wrap "\t"))
(p.after (l.this "\\b") (parser/wrap "\b"))
(p.after (l.this "\\n") (parser/wrap "\n"))
(p.after (l.this "\\r") (parser/wrap "\r"))
(p.after (l.this "\\f") (parser/wrap "\f"))
(p.after (l.this "\\\"") (parser/wrap "\""))
(p.after (l.this "\\\\") (parser/wrap "\\"))))
(def: string~
(l.Lexer String)
(<| (l.enclosed ["\"" "\""])
(loop [_ []])
(do p.Monad<Parser>
[chars (l.some (l.none-of "\\\""))
stop l.peek])
(if (text/= "\\" stop)
(do @
[escaped escaped~
next-chars (recur [])]
(wrap ($_ text/compose chars escaped next-chars)))
(wrap chars))))
(def: (kv~ json~)
(-> (-> Unit (l.Lexer JSON)) (l.Lexer [String JSON]))
(do p.Monad<Parser>
[key string~
_ space~
_ (l.this ":")
_ space~
value (json~ [])]
(wrap [key value])))
(do-template [<name> <type> <open> <close> <elem-parser> <prep>]
[(def: (<name> json~)
(-> (-> Unit (l.Lexer JSON)) (l.Lexer <type>))
(do p.Monad<Parser>
[_ (l.this <open>)
_ space~
elems (p.sep-by data-sep <elem-parser>)
_ space~
_ (l.this <close>)]
(wrap (<prep> elems))))]
[array~ Array "[" "]" (json~ []) sequence.from-list]
[object~ Object "{" "}" (kv~ json~) (dict.from-list text.Hash<Text>)]
)
(def: (json~' _)
(-> Unit (l.Lexer JSON))
($_ p.alt null~ boolean~ number~ string~ (array~ json~') (object~ json~')))
(struct: #export _ (Codec Text JSON)
(def: encode show-json)
(def: decode (function [input] (l.run input (json~' [])))))
|