diffusion/src/node_modules/serialisers/long-encoded-enum-set-serialiser.js

Diffusion JavaScript client

var Codec = require("io/codec");
var BEES = require("serialisers/byte-encoded-enum-serialiser");
var Long = require("long");
var Set = require('core-js/library/fn/set');

/** Encodes a set of enums into a bitset stored in a 64 bit integer
 *
 * The enum values must all lie bewteen 0 and 63 inclusive.
 */
var serialiser = {
    /** Reads an enum set from a buffer input stream
     *
     * @param {BufferInputStream} bis thhe buffer input stream
     * @param {any} enumType the enum type
     *
     * @returns {Set} a Set contining the enums stored in the input stream
     */
    read : function(bis, enumType) {
        var enums = new Set();
        var bitmap = Codec.readInt64(bis);
        var shift = 0;

        var enumReader = {
            read: function() {
                return shift;
            }
        };

        while (!bitmap.isZero()) {
            if (!bitmap.and(1).isZero()) {
                enums.add(BEES.read(enumReader, enumType));
            }
            bitmap = bitmap.shiftRight(1);
            shift++;
        }

        return enums;
    },
    /** Writes an enum set to a buffer output stream
     *
     * @param {BufferOutputStream} bos thhe buffer output stream
     * @param {Array|Set} enumSet the set of enums stored in an array or set.
     *        The only requirement is the presence of a forEach method.
     *        All enum values stored in the set must lie between 0 and 63 inclusive.
     */
    write : function(bos, enumSet) {
        var bitmap = Long.UZERO;

        var enumWriter = {
            write: function(val) {
                if (val>=64) {
                    throw new Error("Cannot encode enum in long, " + val + " >= 64");
                }
                bitmap = bitmap.or(Long.ONE.shiftLeft(val));
            }
        };

        enumSet.forEach(function(e) {
            BEES.write(enumWriter, e);
        });

        Codec.writeInt64(bos, bitmap);

    }
};

module.exports = serialiser;