diffusion/src/node_modules/data/record/recordv2-parser.js

Diffusion JavaScript client

var RECORD_DELIMITER = 0x1;
var FIELD_DELIMITER = 0x2;
var RECORD_MU = 0x4;
var FIELD_MU = 0x5;

module.exports.parse = function(bytes, offset, length) {
    offset = offset || 0;
    length = length || bytes.length;

    // Empty butes returns empty record list
    if (length === 0) {
        return [];
    }

    // Record MU returns single empty record
    if (length === 1 && bytes[offset] === RECORD_MU) {
        return [[]];
    }

    // Process all records
    var records = [];
    var fields = [];

    var pos = offset;

    for (var i = offset; i < length; ++i) {
        if (bytes[i] === RECORD_DELIMITER) {
            processRecordDelimiter(bytes, records, pos, i, fields);
            pos = i + 1;
        } else if (bytes[i] === FIELD_DELIMITER) {
            addField(bytes, records, pos, i, fields);
            pos = i + 1;
        }
    }

    processEnd(bytes, records, pos, length, fields);
    return records;
};

function processRecordDelimiter(bytes, records, startPos, endPos, fields) {
    var written = false;

    // If we have a field add it to list
    if (startPos < endPos) {
        written = addField(bytes, records, startPos, endPos, fields);
    } else {
        // Buf if we're not at the start of content && the last delimiter was for a field
        // it implies an empty field
        if (startPos > 0 && bytes[startPos - 1] === FIELD_DELIMITER) {
            fields.push("");
        }
    }

    if (!written) {
        records.push([].concat(fields));
    }

    // Clear fields array
    fields.length = 0;
}

function processEnd(bytes, records, startPos, endPos, fields) {
    if (endPos > startPos) {
        addField(bytes, records, startPos, endPos, fields);
    } else {
        var endByte = bytes[endPos - 1];

        if (endByte === RECORD_DELIMITER) {
            records.push([]);
        } else if (endByte === FIELD_DELIMITER) {
            fields.push("");
        }
    }

    if (fields.length) {
        records.push([].concat(fields));
    }
}

function addField(bytes, records, startPos, endPos, fields) {
    var len = endPos - startPos;

    if (fields.length === 0 && len === 1 && bytes[startPos] === FIELD_MU) {
        records.push([""]);
        return true;
    } else {
        fields.push(bytes.toString("utf8", startPos, endPos));
    }
}