gecko/intl/locale/src/PluralForm.jsm

/* ***** 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 Plural Form l10n Code.
 *
 * The Initial Developer of the Original Code is
 * Edward Lee <edward.lee@engineering.uiuc.edu>.
 * Portions created by the Initial Developer are Copyright (C) 2008
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * 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 ***** */

EXPORTED_SYMBOLS = [ "PluralForm" ];

/**
 * This module provides the PluralForm object which contains a method to figure
 * out which plural form of a word to use for a given number based on the
 * current localization.
 *
 * See: http://developer.mozilla.org/en/docs/Localization_and_Plurals
 *
 * List of methods:
 *
 * string pluralForm
 * get(int aNum, string aWords)
 */

const Cc = Components.classes;
const Ci = Components.interfaces;

const kIntlProperties = "chrome://global/locale/intl.properties";

// These are the available plural functions that give the appropriate index
// based on the plural rule number specified
let gFunctions = [
  function(n) 0,
  function(n) n!=1?1:0,
  function(n) n>1?1:0,
  function(n) n%10==1&&n%100!=11?1:n!=0?2:0,
  function(n) n==1?0:n==2?1:2,
  function(n) n==1?0:n==0||n%100>0&&n%100<20?1:2,
  function(n) n%10==1&&n%100!=11?0:n%10>=2&&(n%100<10||n%100>=20)?2:1,
  function(n) n%10==1&&n%100!=11?0:n%10>=2&&n%10<=4&&(n%100<10||n%100>=20)?1:2,
  function(n) n==1?0:n>=2&&n<=4?1:2,
  function(n) n==1?0:n%10>=2&&n%10<=4&&(n%100<10||n%100>=20)?1:2,
  function(n) n%100==1?0:n%100==2?1:n%100==3||n%100==4?2:3
];

let PluralForm = {
  /**
   * Get the correct plural form of a word based on the number
   *
   * @param aNum
   *        The number to decide which plural form to use
   * @param aWords
   *        A semi-colon (;) separated string of words to pick the plural form
   * @return The appropriate plural form of the word
   */
  get: (function initGetPluralForm()
  {
    // initGetPluralForm gets called right away when this module is loaded and
    // creates getPluralForm function. The function it creates is based on the
    // value of pluralRule specified in the intl stringbundle.
    // See: http://developer.mozilla.org/en/docs/Localization_and_Plurals

    // Get the plural rule number from the intl stringbundle
    let ruleNum = Number(Cc["@mozilla.org/intl/stringbundle;1"].
      getService(Ci.nsIStringBundleService).createBundle(kIntlProperties).
      GetStringFromName("pluralRule"));

    // Default to "all plural" if the value is out of bounds or invalid
    if (ruleNum < 0 || ruleNum >= gFunctions.length || isNaN(ruleNum)) {
      log(["Invalid rule number: ", ruleNum, " -- defaulting to 0"]);
      ruleNum = 0;
    }

    // Return a function that gets the right plural form
    let pluralFunc = gFunctions[ruleNum];
    return function(aNum, aWords) {
      // Figure out which index to use for the semi-colon separated words
      let index = pluralFunc(aNum ? Number(aNum) : 0);
      let words = aWords ? aWords.split(/;/) : [""];

      let ret = words[index];

      // Check for array out of bounds or empty strings
      if ((ret == undefined) || (ret == "")) {
        // Display a message in the error console
        log(["Index #", index, " of '", aWords, "' for value ", aNum,
            " is invalid -- plural rule #", ruleNum]);

        // Default to the first entry (which might be empty, but not undefined)
        ret = words[0];
      }

      return ret;
    };
  })(),
};

/**
 * Private helper function to log errors to the error console and command line
 *
 * @param aMsg
 *        Error message to log or an array of strings to concat
 */
function log(aMsg)
{
  let msg = "PluralForm.jsm: " + (aMsg.join ? aMsg.join("") : aMsg);
  Cc["@mozilla.org/consoleservice;1"].getService(Ci.nsIConsoleService).
    logStringMessage(msg);
  dump(msg + "\n");
}