Files
tubestation/addon-sdk/source/lib/sdk/system/environment.js
2013-08-20 18:24:12 -07:00

61 lines
2.4 KiB
JavaScript

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
'use strict';
module.metadata = {
"stability": "stable"
};
const { Cc, Ci } = require('chrome');
const { get, set, exists } = Cc['@mozilla.org/process/environment;1'].
getService(Ci.nsIEnvironment);
exports.env = Proxy.create({
// XPCOM does not provides a way to enumerate environment variables, so we
// just don't support enumeration.
getPropertyNames: function() [],
getOwnPropertyNames: function() [],
enumerate: function() [],
keys: function() [],
// We do not support freezing, cause it would make it impossible to set new
// environment variables.
fix: function() undefined,
// We present all environment variables as own properties of this object,
// so we just delegate this call to `getOwnPropertyDescriptor`.
getPropertyDescriptor: function(name) this.getOwnPropertyDescriptor(name),
// If environment variable with this name is defined, we generate proprety
// descriptor for it, otherwise fall back to `undefined` so that for consumer
// this property does not exists.
getOwnPropertyDescriptor: function(name) {
return !exists(name) ? undefined : {
value: get(name),
enumerable: false, // Non-enumerable as we don't support enumeration.
configurable: true, // Configurable as it may be deleted.
writable: true // Writable as we do support set.
}
},
// New environment variables can be defined just by defining properties
// on this object.
defineProperty: function(name, { value }) set(name, value),
delete: function(name) {
set(name, null);
return true;
},
// We present all properties as own, there for we just delegate to `hasOwn`.
has: function(name) this.hasOwn(name),
// We do support checks for existence of an environment variable, via `in`
// operator on this object.
hasOwn: function(name) exists(name),
// On property get / set we do read / write appropriate environment variables,
// please note though, that variables with names of standard object properties
// intentionally (so that this behaves as normal object) can not be
// read / set.
get: function(proxy, name) Object.prototype[name] || get(name) || undefined,
set: function(proxy, name, value) Object.prototype[name] || set(name, value)
});