@masala/parser/src/lib/standard/json/jsonparser.js

Masala Parser

/*
 * Masala Parser
 * https://github.com/masala/masala-parser
 *
 * Copyright (c) 2016-2025 Didier Plaindoux & Nicolas Zozol
 * Licensed under the LGPL3 license.
 */

import { GenLex } from '../../genlex/genlex.js'

import { F } from '../../parsec/index.js'
import { C, N } from '../../parsec/index.js'

//
// Facilities
//

let genlex = new GenLex()
genlex.keywords(['null', 'false', 'true', '{', '}', '[', ']', ':', ','])
let number = genlex.tokenize(N.number(), 'number', 1100)
let string = genlex.tokenize(C.stringLiteral(), 'string', 800)

function tkKey(s) {
    return genlex.get(s)
}

// unit -> Parser ? Token
function arrayOrNothing() {
    // FIXME: ES2015 code not great
    var value = [],
        addValue = (e) => {
            value = value.concat(e)
        },
        getValue = () => value,
        item = F.lazy(expr).map(addValue)
    return item
        .then(tkKey(',').thenRight(item).optrep().array())
        .opt()
        .map(getValue)
}

// unit -> Parser ? Token
function objectOrNothing() {
    // FIXME: ES2015 code not great
    var value = {},
        addValue = (e) => {
            value[e[0]] = e[1]
        },
        getValue = () => value,
        attribute = string
            .thenLeft(tkKey(':'))
            .then(F.lazy(expr))
            .array()
            .map(addValue)
    return attribute
        .thenLeft(tkKey(',').then(attribute).optrep())
        .array()
        .opt()
        .map(getValue)
}

// unit -> Parser ? Token
function expr() {
    return number
        .or(string)
        .or(tkKey('null').returns(null))
        .or(tkKey('true').returns(true))
        .or(tkKey('false').returns(false))
        .or(
            tkKey('[')
                .thenRight(F.lazy(arrayOrNothing))
                .thenLeft(tkKey(']'))
                .single(),
        )
        .or(
            tkKey('{')
                .thenRight(F.lazy(objectOrNothing))
                .thenLeft(tkKey('}'))
                .single(),
        )
}

//const parse =
export default {
    parse: function (source) {
        const parser = genlex.use(expr().thenLeft(F.eos()).single())

        return parser.parse(source, 0)
    },
}