jsonast/dist/src/index.js

a json to ast parser which allows error recovery

"use strict";
var character_stream_1 = require('./character-stream');
/**
 * Parses a given string into a Json AST.
 * This parser does some error correction (notably missing comma in objects and arrays).
 * The template parameter could be used to qualify the result AST.
 *
 * @export
 * @param {string} text The Json text to parse
 * @returns {JsonObject|JsonArray} Either a Json Object or Json Array AST node
 */
function parse(text) {
    var result = undefined;
    var cs = new character_stream_1.CharacterStream(text);
    ws(cs);
    if (cs.ch === '{') {
        result = object(cs);
    }
    else if (cs.ch === '[') {
        result = array(cs);
    }
    ws(cs);
    if (!cs.eoi) {
        throw new Error("Unexpected character '" + cs.ch + "' at " + cs.line + ":" + cs.column + ". Expected end of input.");
    }
    return result;
}
Object.defineProperty(exports, "__esModule", { value: true });
exports.default = parse;
function object(cs) {
    function members(cs1) {
        function pair(cs2) {
            ws(cs2);
            var key = string(cs2);
            ws(cs2);
            cs2.accept(':');
            return {
                key: key,
                value: value(cs2)
            };
        }
        var members = [];
        var next = true;
        while (next) {
            members.push(pair(cs1));
            ws(cs1);
            if (cs1.ch === ',') {
                cs1.next();
            }
            else if (cs1.ch === '"') {
            }
            else {
                next = false;
            }
        }
        return members;
    }
    var ast = {
        type: 'object',
        pos: {
            start: cs.pos,
            end: cs.pos
        }
    };
    ws(cs);
    cs.accept('{');
    ws(cs);
    if (cs.ch === '"') {
        ast.members = members(cs);
    }
    ws(cs);
    cs.accept('}');
    ast.pos.end = cs.pos;
    return ast;
}
function array(cs) {
    var ast = {
        type: 'array',
        pos: {
            start: cs.pos,
            end: cs.pos
        }
    };
    ws(cs);
    cs.accept('[');
    if (cs.ch !== ']') {
        ast.elements = [];
        var next = true;
        while (next) {
            ast.elements.push(value(cs));
            ws(cs);
            if (cs.ch === ',') {
                cs.next();
            }
            else if (cs.ch !== ']') {
            }
            else {
                next = false;
            }
        }
    }
    ws(cs);
    cs.accept(']');
    ast.pos.end = cs.pos;
    return ast;
}
function value(cs) {
    ws(cs);
    switch (cs.ch) {
        case '"':
            return string(cs);
        case '{':
            return object(cs);
        case '[':
            return array(cs);
        case 't':
            return trueLiteral(cs);
        case 'f':
            return falseLiteral(cs);
        case 'n':
            return nullLiteral(cs);
        default:
            return number(cs);
    }
}
function string(cs) {
    var start = cs.pos;
    var value = '';
    cs.accept('"');
    while (cs.ch !== '"') {
        value += cs.ch;
        cs.next();
    }
    cs.accept('"');
    return {
        type: 'string',
        value: value,
        pos: {
            start: start,
            end: cs.pos
        }
    };
}
function trueLiteral(cs) {
    ws(cs);
    var start = cs.pos;
    cs.accept('t');
    cs.accept('r');
    cs.accept('u');
    cs.accept('e');
    return {
        type: 'true',
        pos: {
            start: start,
            end: cs.pos
        }
    };
}
function falseLiteral(cs) {
    ws(cs);
    var start = cs.pos;
    cs.accept('f');
    cs.accept('a');
    cs.accept('l');
    cs.accept('s');
    cs.accept('e');
    return {
        type: 'false',
        pos: {
            start: start,
            end: cs.pos
        }
    };
}
function nullLiteral(cs) {
    ws(cs);
    var start = cs.pos;
    cs.accept('n');
    cs.accept('u');
    cs.accept('l');
    cs.accept('l');
    return {
        type: 'null',
        pos: {
            start: start,
            end: cs.pos
        }
    };
}
function number(cs) {
    function digit() {
        var number = '';
        var ch = cs.ch;
        if (ch === '0' || ch === '1' || ch === '2' || ch === '3' || ch === '4' ||
            ch === '5' || ch === '6' || ch === '7' || ch === '8' || ch === '9') {
            number = ch;
            cs.next();
        }
        return number;
    }
    function digits() {
        var number = digit();
        var temp = digit();
        while (temp !== '') {
            number += temp;
            temp = digit();
        }
        return number;
    }
    var start = cs.pos;
    var negative = cs.skip('-') ? '-' : '';
    var int;
    if (cs.ch === '0') {
        int = cs.ch;
        cs.next();
    }
    else {
        int = digits();
    }
    var frac = '';
    if (cs.ch === '.') {
        cs.next();
        frac = '.' + digits();
    }
    var exp = '';
    if (cs.ch === 'e' || cs.ch === 'E') {
        cs.next();
        exp = 'e';
        exp += cs.skip('+') ? '+' : '';
        exp += cs.skip('-') ? '-' : '';
        exp += digits();
    }
    return {
        type: 'number',
        value: parseFloat("" + negative + int + frac + exp),
        pos: {
            start: start,
            end: cs.pos
        }
    };
}
function ws(cs) {
    var next = true;
    while (next) {
        next = cs.skip(' ') ||
            cs.skip('\t') ||
            cs.skip('\n') ||
            cs.skip('\r');
    }
}
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