gecko/services/sync/modules/ext/Preferences.js

/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is Preferences.
 *
 * The Initial Developer of the Original Code is Mozilla.
 * Portions created by the Initial Developer are Copyright (C) 2008
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *   Myk Melez <myk@mozilla.org>
 *   Daniel Aquino <mr.danielaquino@gmail.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 *
 * ***** END LICENSE BLOCK ***** */

let EXPORTED_SYMBOLS = ["Preferences"];

const Cc = Components.classes;
const Ci = Components.interfaces;
const Cr = Components.results;
const Cu = Components.utils;

function Preferences(prefBranch) {
  if (prefBranch)
    this._prefBranch = prefBranch;
}

Preferences.prototype = {
  _prefBranch: "",

  // Preferences Service

  get _prefSvc() {
    let prefSvc = Cc["@mozilla.org/preferences-service;1"].
                  getService(Ci.nsIPrefService).
                  getBranch(this._prefBranch).
                  QueryInterface(Ci.nsIPrefBranch2);
    this.__defineGetter__("_prefSvc", function() prefSvc);
    return this._prefSvc;
  },

  /**
    * Get the value of a pref, if any; otherwise return the default value.
    *
    * @param   prefName      the name of the pref to get
    * @param   defaultValue  the default value, if any
    *
    * @returns the value of the pref, if any; otherwise the default value
    */
  get: function(prefName, defaultValue) {
    if (isArray(prefName))
      return prefName.map(function(v) this.get(v), this);

    switch (this._prefSvc.getPrefType(prefName)) {
      case Ci.nsIPrefBranch.PREF_STRING:
        return this._prefSvc.getComplexValue(prefName, Ci.nsISupportsString).data;

      case Ci.nsIPrefBranch.PREF_INT:
        return this._prefSvc.getIntPref(prefName);

      case Ci.nsIPrefBranch.PREF_BOOL:
        return this._prefSvc.getBoolPref(prefName);

      case Ci.nsIPrefBranch.PREF_INVALID:
      default:
        return defaultValue;
    }
  },

  set: function(prefName, prefValue) {
    if (isObject(prefName)) {
      for (let [name, value] in Iterator(prefName))
        this.set(name, value);
      return;
    }

    switch (typeof prefValue) {
      case "number":
        this._prefSvc.setIntPref(prefName, prefValue);
        if (prefValue % 1 != 0)
          Cu.reportError("WARNING: setting " + prefName + " pref to non-integer number " +
                         prefValue + " converts it to integer number " + this.get(prefName) +
                         "; to retain precision, store non-integer numbers as strings");
        break;

      case "boolean":
        this._prefSvc.setBoolPref(prefName, prefValue);
        break;

      case "string":
      default: {
        let string = Cc["@mozilla.org/supports-string;1"].
                     createInstance(Ci.nsISupportsString);
        string.data = prefValue;
        this._prefSvc.setComplexValue(prefName, Ci.nsISupportsString, string);
        break;
      }
    }
  },

  reset: function(prefName) {
    if (isArray(prefName)) {
      prefName.map(function(v) this.reset(v), this);
      return;
    }

    try {
      this._prefSvc.clearUserPref(prefName);
    }
    catch(ex) {
      // The pref service throws NS_ERROR_UNEXPECTED when the caller tries
      // to reset a pref that doesn't exist or is already set to its default
      // value.  This interface fails silently in those cases, so callers
      // can unconditionally reset a pref without having to check if it needs
      // resetting first or trap exceptions after the fact.  It passes through
      // other exceptions, however, so callers know about them, since we don't
      // know what other exceptions might be thrown and what they might mean.
      if (ex.result != Cr.NS_ERROR_UNEXPECTED)
        throw ex;
    }
  },

  // FIXME: make the methods below accept an array of pref names.

  has: function(prefName) {
    return (this._prefSvc.getPrefType(prefName) != Ci.nsIPrefBranch.PREF_INVALID);
  },

  modified: function(prefName) {
    return (this.has(prefName) && this._prefSvc.prefHasUserValue(prefName));
  },

  locked: function(prefName) {
    return this._prefSvc.isLocked(prefName);
  },

  lock: function(prefName) {
    this._prefSvc.lockPref(prefName);
  },

  unlock: function(prefName) {
    this._prefSvc.unlockPref(prefName);
  },

  resetBranch: function(prefBranch) {
    try {
      this._prefSvc.resetBranch(prefBranch);
    }
    catch(ex) {
      // The current implementation of nsIPrefBranch in Mozilla
      // doesn't implement resetBranch, so we do it ourselves.
      if (ex.result == Cr.NS_ERROR_NOT_IMPLEMENTED)
        this.reset(this._prefSvc.getChildList(prefBranch, []));
      else
        throw ex;
    }
  }

};

// Give the constructor the same prototype as its instances, so users can access
// preferences directly via the constructor without having to create an instance
// first.
Preferences.__proto__ = Preferences.prototype;

function isArray(val) {
  // We can't check for |val.constructor == Array| here, since we might have
  // a different global object, so we check the constructor name instead.
  return (typeof val == "object" && val.constructor.name == Array.name);
}

function isObject(val) {
  // We can't check for |val.constructor == Object| here, since we might have
  // a different global object, so we check the constructor name instead.
  return (typeof val == "object" && val.constructor.name == Object.name);
}