SQL Parser in Javascript

sql-parser.js

'use strict';
(exports => {

    // console.clear();
    //
    // let SAMPLE = ``+
    //     `SELECT\n`+
    //     ` Instance.Instance.Id AS Name,\n`+
    //     ` Instance.Instance.PrivateIpAddress AS "IP Address",\n`+
    //     ` Instance.Instance.LaunchTime AS Created,\n`+
    //     ` Instance.Instance.Placement.AvailabilityZone AS Location,\n`+
    //     ` Instance.Instance.Tags.*.[Key=Name].Value AS "Tech owner"\n`+
    //     `FROM ec2`;
    //
    // SAMPLE = `SELECT Instance.Instance.Id AS Name, Instance.Instance.PrivateIpAddress AS \"IP Address\", Instance.Instance.LaunchTime AS Created, Instance.Instance.Placement.AvailabilityZone AS Location, Instance.Instance.Tags.*.[Key=Name].Value AS \"Tech owner\" FROM ec2`;

    const RX_STATEMENT = /^\s*select\s+([\s\S]+)\s+from\s+([^\s]+?)\s*$/i;
    const RX_FIELD = /^([^\s]+?)(?:\s+as\s+(['"]?)(.+?)\2)?\s*(?:,\s*|$)/i;
    const RX_SEGMENT = /^\s*(?:\[\s*([^\s=[\]]*)(?:\s*=\s*(['"]?)(.*?)\2)?\s*\]|(\*)|([^\s]+?))\s*(?:\.\s*|$)/i;

    exports.sqlesque = { parse: s => {
        let m = s.match(RX_STATEMENT);
        if (null == m) throw Error("Invalid statement.");
        let [,fields,table] = s.match(RX_STATEMENT);
        const r = { table: table, fields: [] };

        while (null != (m = RX_FIELD.exec(fields))) {
            let [,field,,alias=''] = m;
            const _field = { segments: [], alias: alias || field };
            fields = fields.substr(m[0].length);
            while (null != (m = RX_SEGMENT.exec(field))) {
                field = field.substr(m[0].length);
                let [,attrName,,attrValue,wildcard,key] = m;
                if (null != attrName) {
                    _field.segments.push({
                        type: 'attr',
                        name: attrName,
                        value: attrValue,
                    });
                }
                else if (null != wildcard) {
                    _field.segments.push({
                        type: 'wildcard',
                    });
                }
                else if (null != key) {
                    _field.segments.push({
                        type: 'key',
                        key: key
                    });
                }
            }
            r.fields.push(_field);
        };

        return r;
    }};

    // console.log('r', parse(SAMPLE));

})(typeof exports === 'undefined' ? window : exports); // browser compatible