Signal-Desktop/js/bimap.js

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/*global $, Whisper, Backbone, textsecure, extension*/
/* vim: ts=4:sw=4:expandtab:
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
// A bidirectional hash that allows constant-time lookup for
// key -> value and value -> key
(function () {
'use strict';
window.Whisper = window.Whisper || {};
function Bimap (map1, map2) {
if (typeof map1 !== 'string' || typeof map2 !== 'string') {
throw 'Expected two map name strings as arguments';
}
this.bijection = {};
this.bijection[map1] = map2;
this.bijection[map2] = map1;
// makes accessing the maps clearer
this[map1] = {};
this[map2] = {};
this[map1 + 'From'] = function (key) { return this[map2][key]; };
this[map2 + 'From'] = function (key) { return this[map1][key]; };
}
Bimap.prototype.add = function (obj) {
if (typeof obj !== 'object') {
throw 'Expected an object as an argument';
}
var keys = Object.keys(obj);
var map1 = keys[0];
var map2 = keys[1];
if (this.bijection[map1] !== map2) {
throw 'Expected the argument\'s keys to correspond to the Bimap\'s two map names';
}
this[map1][obj[map1]] = obj[map2];
this[map2][obj[map2]] = obj[map1];
};
Bimap.prototype.remove = function remove (map, key) {
var bijection = this.bijection[map];
var correspondingKey = this[map][key];
// delete from the bijection
delete this[bijection][correspondingKey];
// delete from the specified map
delete this[map][key];
return correspondingKey;
};
// export
Whisper.Bimap = Bimap;
})();