Session Decode

session_decode.js

module.exports.session_decode =function (data) {
    // *       example: session_decode('firstName|s:5:"Kevin";midName|s:3:"van";surName|s:9:"Zonneveld"');
    // *       returns: {firstName: 'Kevin', midName: 'van', surName: 'Zonneveld'}

    var that = this,
        utf8Overhead = function (chr) {
            // http://phpjs.org/functions/unserialize:571#comment_95906
            var code = chr.charCodeAt(0);
            if (code < 0x0080) {
                return 0;
            }
            if (code < 0x0800) {
                return 1;
            }
            return 2;
        },
        error = function (type, msg, filename, line) {
            throw new that.window[type](msg, filename, line);
        },
        read_until = function (data, offset, stopchr) {
            var i = 2, buf = [], chr = data.slice(offset, offset + 1);

            while (chr != stopchr) {
                if ((i + offset) > data.length) {
                    error('Error', 'Invalid');
                }
                buf.push(chr);
                chr = data.slice(offset + (i - 1), offset + i);
                i += 1;
            }
            return [buf.length, buf.join('')];
        },
        read_chrs = function (data, offset, length) {
            var i, chr, buf;

            buf = [];
            for (i = 0; i < length; i++) {
                chr = data.slice(offset + (i - 1), offset + i);
                buf.push(chr);
                length -= utf8Overhead(chr);
            }
            return [buf.length, buf.join('')];
        },
        _unserialize = function (data, offset) {
            var dtype, dataoffset, keyandchrs, keys,
                readdata, readData, ccount, stringlength,
                i, key, kprops, kchrs, vprops, vchrs, value,
                chrs = 0,
                typeconvert = function (x) {
                    return x;
                };

            if (!offset) {
                offset = 0;
            }
            dtype = (data.slice(offset, offset + 1)).toLowerCase();

            dataoffset = offset + 2;

            switch (dtype) {
                case 'i':
                    typeconvert = function (x) {
                        return parseInt(x, 10);
                    };
                    readData = read_until(data, dataoffset, ';');
                    chrs = readData[0];
                    readdata = readData[1];
                    dataoffset += chrs + 1;
                    break;
                case 'b':
                    typeconvert = function (x) {
                        return parseInt(x, 10) !== 0;
                    };
                    readData = read_until(data, dataoffset, ';');
                    chrs = readData[0];
                    readdata = readData[1];
                    dataoffset += chrs + 1;
                    break;
                case 'd':
                    typeconvert = function (x) {
                        return parseFloat(x);
                    };
                    readData = read_until(data, dataoffset, ';');
                    chrs = readData[0];
                    readdata = readData[1];
                    dataoffset += chrs + 1;
                    break;
                case 'n':
                    readdata = null;
                    break;
                case 's':
                    ccount = read_until(data, dataoffset, ':');
                    chrs = ccount[0];
                    stringlength = ccount[1];
                    dataoffset += chrs + 2;

                    readData = read_chrs(data, dataoffset + 1, parseInt(stringlength, 10));
                    chrs = readData[0];
                    readdata = readData[1];
                    dataoffset += chrs + 2;
                    if (chrs != parseInt(stringlength, 10) && chrs != readdata.length) {
                        error('SyntaxError', 'String length mismatch');
                    }
                    break;
                case 'a':
                    readdata = {};

                    keyandchrs = read_until(data, dataoffset, ':');
                    chrs = keyandchrs[0];
                    keys = keyandchrs[1];
                    dataoffset += chrs + 2;

                    for (i = 0; i < parseInt(keys, 10); i++) {
                        kprops = _unserialize(data, dataoffset);
                        kchrs = kprops[1];
                        key = kprops[2];
                        dataoffset += kchrs;

                        vprops = _unserialize(data, dataoffset);
                        vchrs = vprops[1];
                        value = vprops[2];
                        dataoffset += vchrs;

                        readdata[key] = value;
                    }

                    dataoffset += 1;
                    break;
                default:
                    error('SyntaxError', 'Unknown / Unhandled data type(s): ' + dtype);
                    break;
            }
            return [dtype, dataoffset - offset, typeconvert(readdata)];
        }
        ;

    dataoffset = 0;
    var res = {};
    while (dataoffset < data.length)
    {
        keyandchrs = read_until(data, dataoffset, '|');
        chrs = keyandchrs[0];
        key = keyandchrs[1];
        dataoffset += chrs + 1;
        subdata = _unserialize((data + ''), dataoffset);
        dataoffset += subdata[1];
        res[key] = subdata[2];

    }
    return res
}