From de34c0ec7b59c75d70ec5a96da09e218c2813d1a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Wang?= <fred.wang@free.fr>
Date: Fri, 2 Aug 2013 17:04:46 +0200
Subject: [PATCH] Implement language fallback. Fix issue #492.

---
 unpacked/MathJax.js | 20 +++++++++++++++++---
 1 file changed, 17 insertions(+), 3 deletions(-)

diff --git a/unpacked/MathJax.js b/unpacked/MathJax.js
index 7210d8013..0e857e02a 100644
--- a/unpacked/MathJax.js
+++ b/unpacked/MathJax.js
@@ -1068,7 +1068,9 @@ MathJax.Localization = {
     en: {menuTitle: "English", isLoaded: true},   // nothing needs to be loaded for this
     de: {menuTitle: "Deutsch"},
     fr: {menuTitle: "Fran\u00E7ais"},
-    it: {menuTitle: "Italiano"}
+    it: {menuTitle: "Italiano"},
+    pt: {menuTitle: "portugus\u00EA", remap: "pt-br"},
+    "pt-br": {menuTitle: "portugu\u00EAs do Brasil"}
   },
 
   //
@@ -1394,8 +1396,20 @@ MathJax.Localization = {
   //  Set the current language
   //
   setLocale: function(locale) {
-    // don't set it if there isn't a definition for it
-    if (this.strings[locale]) {this.locale = locale}
+    // Selection algorithm:
+    // 1) Downcase locale name (e.g. "en-US" => "en-us")
+    // 2) Try a parent language (e.g. "en-us" => "en")
+    // 3) Try the fallback specified in the data (e.g. "pt" => "pt-br")
+    // 4) Otherwise don't change the locale.
+    if (!locale) return;
+    locale = locale.toLowerCase();
+    while (!this.strings[locale]) {
+      var dashPos = locale.lastIndexOf("-");
+      if (dashPos === -1) return;
+      locale = locale.substring(0, dashPos);
+    }
+    var remap = this.strings[locale].remap;
+    this.locale = remap ? remap : locale;
     if (MathJax.Menu) {this.loadDomain("MathMenu")}
   },