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json-parser.lurk
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341 lines (339 loc) · 23.5 KB
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(letrec ((map (lambda (f xs) ;; (a -> b) -> [a] -> [b]
(if xs
(cons (f (car xs))
(map f (cdr xs)))
nil)))
;; (a -> a -> ... -> a -> b) -> [a] -> b
(apply (lambda (f xs)
(if xs
(apply (f (car xs))
(cdr xs))
f)))
;; lurk-rs seems to not support mutual recursion via letrec yet.
;; so I need this fixed point combinator!
;; https://okmij.org/ftp/Computation/fixed-point-combinators.html
;; (Y* fs) = (map (lambda (f) (apply f (Y* fs))) fs)
(Y* (lambda (fs)
((lambda (x) (x x))
(lambda (x)
(map (lambda (f)
(lambda (thunk) ; This thunk is not needed in a lazily evaluated language. Lurk is eager
((apply f (x x)) thunk)))
fs)))))
;; bool -> bool
(not (lambda (x)
(if x nil t)))
;; a -> a -> bool
(neq (lambda (x y)
(not (eq x y))))
;; bool -> bool -> bool
(or (lambda (x y)
(if x x y)))
;; bool -> bool -> bool
(and (lambda (x y)
(if x y x)))
;; int -> string -> (string . string)
(split-at (lambda (index text)
(if (eq index 0)
(cons "" text)
(let ((deep (split-at (- index 1) (cdr text)))
(before-index (car deep))
(after-index (cdr deep)))
(cons (strcons (car text) before-index) after-index)))))
;; (a -> bool) -> [a] -> ([a] . [a])
(split-right (lambda (p xs)
(if xs
(let ((inner (split-right p (cdr xs)))
(before (car inner))
(after (cdr inner)))
(if before
(cons (cons (car xs) before) after)
(if (p (car xs))
(cons (cons (car xs) nil) after)
(cons nil (cons (car xs) after)))))
(cons nil nil))))
;; [a] -> [a] -> [a]
(concat (lambda (xs ys)
(if (or (eq xs "") (eq xs nil)) ys
(cons (car xs) (concat (cdr xs) ys)))))
;; [a] -> int
(length (lambda (xs)
(if (eq xs nil) 0
(+ 1 (length (cdr xs))))))
;; [char] -> string
(chars2str (lambda (xs)
(if xs
(strcons (car xs) (chars2str (cdr xs)))
"")))
;; char -> int
(char2int (lambda (digit)
(if (eq #\0 digit) 0
(if (eq #\1 digit) 1
(if (eq #\2 digit) 2
(if (eq #\3 digit) 3
(if (eq #\4 digit) 4
(if (eq #\5 digit) 5
(if (eq #\6 digit) 6
(if (eq #\7 digit) 7
(if (eq #\8 digit) 8
(if (eq #\9 digit) 9
(if (eq #\a digit) 10
(if (eq #\b digit) 11
(if (eq #\c digit) 12
(if (eq #\d digit) 13
(if (eq #\e digit) 14
(if (eq #\f digit) 15
(if (eq #\A digit) 10
(if (eq #\B digit) 11
(if (eq #\C digit) 12
(if (eq #\D digit) 13
(if (eq #\E digit) 14
(if (eq #\F digit) 15
nil))))))))))))))))))))))))
;; int -> int -> string -> int
(str2int/open (lambda (acc base xs)
(if (eq xs "") acc
(str2int/open (+ (* base acc)
(char2int (car xs)))
base
(cdr xs)))))
;; int -> string -> int
(str2int (str2int/open 0))
;; (string -> (a . string)) -> (string -> (b . string)) -> string -> ((a . b) . string)
(comb/and (lambda (parser1 parser2 text)
(let ((parsed1 (parser1 text))
(result1 (car parsed1))
(remaining1 (cdr parsed1)))
(if parsed1
(let ((parsed2 (parser2 remaining1))
(result2 (car parsed2))
(remaining2 (cdr parsed2)))
(and parsed2
(cons (cons result1 result2) remaining2)))
nil))))
;; (string -> (a . string)) -> (string -> (a . string)) -> string -> (a . string)
(comb/or (lambda (parser1 parser2 text)
(let ((cond (parser1 text)))
(if cond cond (parser2 text)))))
;; (string -> (a . string)) -> string -> (a . string)
(comb/option (lambda (parser text)
(let ((cond (parser text)))
(if cond cond (cons nil text)))))
;; (string -> (a . string)) -> string -> ([a] . string)
(comb/many0 (lambda (parser text)
(let ((parsed1 (parser text))
(result1 (car parsed1))
(remaining1 (cdr parsed1)))
(if parsed1
(let ((parsed2 (comb/many0 parser remaining1))
(result2 (car parsed2))
(remaining2 (cdr parsed2)))
(cons (cons result1 result2) remaining2))
(cons nil text)))))
;; (string -> (a . string)) -> string -> ([a] . string)
(comb/many1 (lambda (parser)
(comb/and parser (comb/many0 parser))))
;; (a -> b) -> (string -> (a . string)) -> string -> (b . string)
(comb/map (lambda (f parser text)
(let ((parsed (parser text))
(result (car parsed))
(remaining (cdr parsed)))
(if parsed
(cons (f result) remaining)
nil))))
;; (string -> (a . string)) -> (string -> (b . string)) -> string -> (a . string)
(comb/car (lambda (parser1 parser2)
(comb/map (lambda (pair) (car pair))
(comb/and parser1 parser2))))
;; (string -> (a . string)) -> (string -> (b . string)) -> string -> (b . string)
(comb/cdr (lambda (parser1 parser2)
(comb/map (lambda (pair) (cdr pair))
(comb/and parser1 parser2))))
;; int -> (string -> (a . string)) -> string -> ([a] . string)
(comb/take (lambda (qty parser text)
(if (eq 0 qty)
(cons nil text)
(let ((parsed1 (parser text))
(result1 (car parsed1))
(remaining1 (cdr parsed1)))
(if parsed1
(let ((parsed2 (comb/take (- qty 1) parser remaining1))
(result2 (car parsed2))
(remaining2 (cdr parsed2)))
(if parsed2
(cons (cons result1 result2) remaining2)
nil))
nil)))))
;; char -> (string -> (a . string)) -> string -> ([a] . string)
(comb/join (lambda (separator parser)
(comb/and parser
(comb/many0 (comb/cdr separator parser)))))
;; json/* takes a string and returns a pair where
;; car: parsed result
;; cdr: remaining string
;; when the parse fails it returns a nil instead of a pair
;; char -> string -> (char . string)
(json/char (lambda (char json)
(if (eq (car json) char)
; I know this looks ridiculous
; This is converting string into (char . string)
(cons (car json) (cdr json))
nil)))
;; string -> (string . string)
(json/spaces (comb/many0 (comb/or (json/char (char 10)) ; line-feed
(comb/or (json/char (char 13)) ; carriage return
(comb/or (json/char (char 9)) ; horizontal tab
(json/char (char 32))))))) ; space
;; string -> (nil . string)
(json/null (lambda (json)
(let ((split (split-at 4 json))
(first-letters (car split))
(rest (cdr split)))
(if (eq first-letters "null")
(cons nil rest)
nil))))
;; string -> (t . string)
(json/true (lambda (json)
(let ((split (split-at 4 json))
(first-letters (car split))
(rest (cdr split)))
(if (eq first-letters "true")
(cons t rest)
nil))))
;; string -> (nil . string)
(json/false (lambda (json)
(let ((split (split-at 5 json))
(first-letters (car split))
(rest (cdr split)))
(if (eq first-letters "false")
(cons nil rest)
nil))))
;; string -> (char . string)
(json/non0 (comb/or (json/char #\1)
(comb/or (json/char #\2)
(comb/or (json/char #\3)
(comb/or (json/char #\4)
(comb/or (json/char #\5)
(comb/or (json/char #\6)
(comb/or (json/char #\7)
(comb/or (json/char #\8)
(json/char #\9))))))))))
;; string -> (char . string)
(json/digit (comb/or (json/char #\0) json/non0))
;; string -> (int . string)
(json/sign (comb/map (lambda (x) (if (eq #\- x) -1 1))
(comb/option (json/char #\-))))
;; string -> ([char] . string)
(json/integer (comb/or (comb/map (lambda (x) nil)
(json/char #\0))
(comb/and json/non0
(comb/many0 json/digit))))
;; string -> ([char] . string)
(json/fraction (comb/option (comb/cdr (json/char #\.)
(comb/map (lambda (chars) (car (split-right (neq #\0) chars)))
(comb/many1 json/digit)))))
;; string -> (int . string)
(json/exponent (comb/map (lambda (num) (or num 0))
(comb/option (comb/map (lambda (xs) (* (car xs) (cdr xs)))
(comb/and (comb/cdr (comb/or (json/char #\E)
(json/char #\e))
(comb/map (lambda (x) (if (eq x #\-) -1 1))
(comb/option (comb/or (json/char #\-)
(json/char #\+)))))
(comb/map (lambda (xs) (str2int 10 (chars2str xs)))
(comb/many1 json/digit)))))))
;; string -> ((int . int) . string)
(json/number (comb/map (lambda (xs)
(let ((sign (car xs))
(integer (car (cdr xs)))
(fraction (car (cdr (cdr xs))))
(exponent (cdr (cdr (cdr xs))))
(split0 (split-right (neq #\0)
(concat integer fraction)))
(numerator (* sign (str2int 10 (chars2str (car split0)))))
(denominator (- (- (length fraction) exponent) (length (cdr split0)))))
(cons numerator denominator)))
; This parser returns a pair of numerator and denominator.
; represented number = numerator / 10^denominator
(comb/and json/sign (comb/and json/integer (comb/and json/fraction json/exponent)))))
;; string -> (char . string)
(json/normal-char (lambda (json)
(if (eq json "") nil
(if (eq #\" (car json)) nil
(if (eq #\\ (car json)) nil
(cons (car json) (cdr json)))))))
;; string -> (char . string)
(json/hex (comb/or json/digit
(comb/or (json/char #\a)
(comb/or (json/char #\b)
(comb/or (json/char #\c)
(comb/or (json/char #\d)
(comb/or (json/char #\e)
(comb/or (json/char #\f)
(comb/or (json/char #\A)
(comb/or (json/char #\B)
(comb/or (json/char #\C)
(comb/or (json/char #\D)
(comb/or (json/char #\E)
(json/char #\F))))))))))))))
;; string -> (char . string)
(json/special-char (comb/cdr (json/char #\\)
(comb/or (comb/map (lambda (x) (char 34))
(json/char #\"))
(comb/or (comb/map (lambda (x) (char 92))
(json/char #\\))
(comb/or (comb/map (lambda (x) (char 47))
(json/char #\/))
(comb/or (comb/map (lambda (x) (char 8))
(json/char #\b))
(comb/or (comb/map (lambda (x) (char 12))
(json/char #\f))
(comb/or (comb/map (lambda (x) (char 10))
(json/char #\n))
(comb/or (comb/map (lambda (x) (char 13))
(json/char #\r))
(comb/or (comb/map (lambda (x) (char 9))
(json/char #\t))
(comb/cdr (json/char #\u)
(comb/map (lambda (xs) (char (str2int 16 (chars2str xs))))
(comb/take 4 json/hex)))))))))))))
;; string -> (string . string)
(json/string (comb/car (comb/map (lambda (x) (chars2str (cdr x)))
(comb/and (json/char #\")
(comb/many0 (comb/or json/normal-char json/special-char))))
(json/char #\")))
;; string -> ([value] . string)
(json/array/open (lambda (array object value)
(comb/car (comb/cdr (json/char (char 91)) ; left square bracket
(comb/or (comb/join (json/char #\,)
value)
(comb/map (lambda (xs) nil)
json/spaces)))
(json/char (char 93))))) ; right square bracket
;; string -> ((string . value) . string)
(json/object/open (lambda (array object value)
(let ((member (comb/cdr json/spaces
(comb/and json/string
(comb/cdr json/spaces
(comb/cdr (json/char #\:) value))))))
(comb/car (comb/cdr (json/char (char 123)) ; left curly bracket
(comb/or (comb/join (json/char #\,) member)
(comb/map (lambda (xs) nil)
json/spaces)))
(json/char (char 125)))))) ; right curly bracket
;; string -> value
(json/value/open (lambda (array object value)
(comb/car (comb/cdr json/spaces
(comb/or (comb/map (lambda (x) (cons :object x)) object)
(comb/or (comb/map (lambda (x) (cons :array x)) array)
(comb/or (comb/map (lambda (x) (cons :string x)) json/string)
(comb/or (comb/map (lambda (x) (cons :number x)) json/number)
(comb/or (comb/map (lambda (x) (cons :null x)) json/null)
(comb/or (comb/map (lambda (x) (cons :bool x)) json/true)
(comb/map (lambda (x) (cons :bool x)) json/false))))))))
json/spaces)))
(mutually-recursive (Y* (cons json/array/open (cons json/object/open (cons json/value/open nil)))))
(json/array (car mutually-recursive))
(json/object (car (cdr mutually-recursive)))
(json/value (car (cdr (cdr mutually-recursive)))))
json/value)