Scryer-Prolog definite clause grammar for JSON

json.pl

% https://www.json.org/json-en.html

:- use_module(library(dcgs)).
:- use_module(library(lists)).

json --> element.

value --> object.
value --> array.
value --> string.
value --> number.
value --> truw.
value --> fals.
value --> null.

truw --> ['t','r','u','e'].

fals --> ['f','a','l','s','e'].

null --> ['n','u','l','l'].

object --> ['{'], ws, ['}'].
object --> ['{'], pairs, ['}'].

pairs --> pair.
pairs --> pair, [','], pairs.

pair --> ws, string, ws, [':'], element.

array --> ['['], ws, [']'].
array --> ['['], elements, [']'].

elements --> element.
elements --> element, [','], elements.

element --> ws, value, ws.

string --> ['"'], characters, ['"'].

characters --> [].
characters --> character, characters.

character --> [C], { \+ member(C, ['"', '\\']) }.
character --> ['\\'], escape.

escape --> ['"'].
escape --> ['\\'].
escape --> ['/'].
escape --> ['b'].
escape --> ['f'].
escape --> ['n'].
escape --> ['r'].
escape --> ['t'].
escape --> ['u'], hexa, hexa, hexa, hexa.

hexa --> digit.
hexa --> ['A'].
hexa --> ['B'].
hexa --> ['C'].
hexa --> ['D'].
hexa --> ['E'].
hexa --> ['F'].
hexa --> ['a'].
hexa --> ['b'].
hexa --> ['c'].
hexa --> ['d'].
hexa --> ['e'].
hexa --> ['f'].

number --> integer, fraction, exponent.

integer --> digit.
integer --> onenine, digits.
integer --> ['-'], digit.
integer --> ['-'], onenine, digits.

digits --> digit.
digits --> digit, digits.

digit --> ['0'].
digit --> onenine.

onenine --> ['0'].
onenine --> ['1'].
onenine --> ['2'].
onenine --> ['3'].
onenine --> ['4'].
onenine --> ['5'].
onenine --> ['6'].
onenine --> ['7'].
onenine --> ['8'].
onenine --> ['9'].

fraction --> [].
fraction --> ['.'], digits.

exponent --> [].
exponent --> ['E'], sign, digits.
exponent --> ['e'], sign, digits.

sign --> [].
sign --> ['+'].
sign --> ['-'].

ws --> [].
ws --> [' '], ws.
ws --> ['\n'], ws.
ws --> ['\t'], ws.
ws --> ['\r'], ws.